US20050171403A1 - Surgical device and method for pericardium retraction - Google Patents

Abstract

A surgical device and method for retracting a pericardium tissue, the surgical device having a tissue-engaging member for providing a negative pressure suction force to the pericardium tissue which is sufficient to retract same. The surgical device may be positioned in a retracting configuration wherein it provides a tensile load on the contacted portion of pericardium tissue thereby also positioning the patient's heart, that is anatomically attached to the pericardium tissue, within the thoracic cavity of the patient. The surgical device may be temporarily coupled to a surgical platform in its retracting configuration.

Description

FIELD OF THE INVENTION
• The present invention relates to the field of surgical apparatus and more specifically, to a tissue retraction device for positioning and orienting a beating heart during cardiac surgery.
BACKGROUND OF THE INVENTION
• Coronary artery bypass graft (CABG) surgery is a widely practised surgical procedure for performing coronary artery revascularization or bypass grafts. This surgical procedure consists of replenishing or augmenting blood flow to a portion of the patient's heart which is being deprived of such flow due to a restriction or blockage in a coronary artery supplying the said portion of the patient's heart. A healthy segment from a blood vessel, such as an artery or a vein converted into an artery, is attached to the patient's vasculature from a point upstream of the coronary artery restriction or blockage to a point downstream thereof, thereby creating the bypass artery and associated bypass blood flow. Since the great majority of CABG surgeries are multi-vessel bypasses, this surgical procedure remains one of the most common and effective treatments for coronary artery disease.
• Traditional CABG surgery has been commonly performed through a midline sternotomy incision, where the patient's sternum is incised and the ribcage retracted to obtain access mainly to the patient's heart, the coronary vessels, and other internal thoracic arteries. Intercostal thoracotomy approaches have also been employed whereby two adjacent ribs are spread apart, at times even removing a length of rib to improve access into the patient's thorax. In both approaches, a surgical retractor is used to spread the patient's skin and bone structure and to maintain an incised opening or surgical window onto the underlying heart and coronary vessels.
• CABG surgery has been traditionally performed with the support of a cardiopulmonary machine, whereby the patient's blood is oxygenated outside the body through extracorporeal circulation (ECC). This allows the surgeon to perform surgical procedures on a near perfectly still heart while the patient's life support is maintained by cardiopulmonary assistance. During traditional CABG surgery, the surgeon or assistant may manually or otherwise manipulate the arrested heart into a position and orientation that yields the best access to the target artery requiring the bypass graft. The great majority of CABG surgeries (approximately 70%) are triple vessel bypass surgeries; that is, at least one bypass graft is performed on each of the anterior, inferior and posterior artery beds of the patient's heart.
• Recently, in an aim to render CABG surgery less invasive to the patient, beating heart CABG surgery is being developed whereby ECC, one of the most invasive aspects of cardiac surgery, is eliminated and coronary artery revascularization is performed directly on the beating heart. One of the challenges in performing beating heart CABG surgery lies in positioning and orienting the beating heart in order to obtain access to the inferior and posterior artery beds, while aiming to minimize physiologically undesirable effects such as hemodynamic instability, arrhythmia, or a precipitous drop in arterial pressure, any of which may occur as a result of such beating heart manipulation. Furthermore, a surgical device which enables manipulation of the beating heart or which restrains its movement or positioning may impose loads and constraints on the beating heart. This may impede the normal beating function of the heart and induce the onset of the physiologically undesirable effects described above. In traditional CABG surgery, the heart is arrested and therefore heart manipulations are well tolerated.
• During CABG surgery or beating heart CABG surgery, the pericardium, namely the substantially thin membranous tissue forming a sac in which the heart and the commencement of the major blood vessels connecting with the heart are contained, is generally incised and unraveled to expose at least a portion of the heart surface which is to receive the bypass graft. The pericardium tissue, unlike the heart, is not beating and it may be separated from the heart surface except in certain locations where it is anatomically attached to the heart. Thus, it is surgically possible in CABG surgery to position and orient the heart through retraction, positioning and loading of the pericardium tissue to obtain access to the inferior and posterior coronary artery beds. In beating heart CABG, heart manipulations achieved through retraction of the pericardium tissue tends to reduce the likelihood of inducing trauma to the beating heart and tends to minimize the physiologically undesirable effects mentioned above, since direct contact with the beating heart is avoided. One such beating heart manipulation consists of “verticalizing” the heart in order to gain access to the posterior artery bed. In this maneuver, the pericardium is engaged close to the base of the heart, preferably 1.5 inches from pericardial reflection, and the apex of the heart is rotated outward from retracted chest cavity through the tensile loads applied to the engaged pericardium. The longitudinal axis of the beating heart thereby assumes a substantially vertical orientation.
• The desired position and orientation of a beating heart may be maintained, at least in part, by maintaining retraction loads applied to the pericardium tissue and securing the surgical apparatus that applies the tensile load to pericardium tissue. During CABG surgery, a deployed surgical retractor provides a suitable stable platform for the securement of the pericardium retraction loads. The pericardium tissue may be engaged by a variety of methods. Sutures such as traction or stay sutures have been generally employed in cardiac surgery to retract tissue during a surgical intervention. Traditionally sutures consist of tissue piercing member such as a relatively sharp needle and a length of wire-like filament such as a suture line integrally attached to the blunt end of said needle. Pericardium retraction may be achieved through the application of pericardial traction sutures whereby the needle pierces the pericardium tissue, threading a certain length of suture line through the pierced pericardium tissue, and pulling simultaneously on both the resulting lengths of suture line; that is, the length between the pierced tissue and the free end of the suture line, and the length between the pierced tissue and the needle-bearing end of the suture line, to displace the pericardium tissue and consequently the beating heart anatomically attached to the pericardium.
• In order to “verticalize” a beating with pericardial traction sutures, a number of such sutures must be inserted through and engaged with the pericardium tissue preferably along its pericardial reflection in order to get the desired lifting of the heart apex and consequently the best exposure to the posterior coronary bed. For example, one traction suture may be placed between the superior and inferior pulmonary vein, a second one below the inferior pulmonary vein, a third one midway between the apex of the heart and the inferior pulmonary vein, and a fourth one towards the diaphragmatic face near the inferior vena cava. Pericardium retraction loads are subsequently applied to each of these traction sutures independently. The resulting lengths of suture line must then be secured to a stable surgical platform such as the sternum retractor to maintain the desired retraction load on the pericardium tissue.
• During the placement of these pericardial traction sutures deep within the patient's thorax and close to the base of the beating heart, the surgeon's view of the body tissue contained beyond the unraveled pericardium tissue is hindered. Consequently, because of this blind installation, the risk of unintentionally puncturing other underlying body tissue with the tissue piercing needle may lead to operative or postoperative complications, especially when a number of such sutures is required. For instance, an inadvertent puncture of the pleura and lungs may lead to a pneumothorax injury if undetected. The placement of deep pericardial traction sutures may therefore be challenging.
• Pericardial traction sutures may be characterized by additional drawbacks. For example the placement of such sutures may be time consuming, since securing of the pericardium retraction load through the manual tying of the suture line lengths is often a multiple step threading and knotting procedure. As well, the placement of pericardial traction sutures may in some instances be cumbersome due to poor access to the deeper portions of pericardial tissue and due to the number of traction sutures required to achieve beating heart “verticalization”. Lastly, these sutures may not be conducive to permitting easy readjustment of the magnitude of the desired tensile load on the pericardium tissue, or of the direction of said load relative to the pericardium tissue. Typically readjustments of this type may require a surgeon to untie and retie suture line lengths or to cut the existing suture line having the undesired retraction load and replace it with a new suture that must repierce the pericardium tissue and again be secured.
• Generally, adjustment of the desired tensile load on the pericardium tissue by cutting an existing suture line and repiercing a new suture line is not desirable. First, the process of placing a pericardial traction suture requires considerable manual dexterity, at times requiring the help of an assistant. The process is therefore tedious and time consuming. Second, a repiercing of the pericardium tissue with a subsequent traction suture tends to increase the likelihood of inducing tissue trauma or tissue tearing which may have to be surgically repaired.
• Based on the foregoing, it would be advantageous to provide a means for pericardium retraction which is less invasive to the pericardium tissue and underlying coronary tissue, and which is not compromised by a surgeon's lack of vision behind the pericardium tissue. Since the pericardium is a relatively thin, membranous tissue which is incised and unraveled to expose the underlying heart surface prior to performing cardiac surgery, it would be advantageous to have the pericardium tissue engaged by a negative pressure suction force. It would be a further advantage to have the pericardium contacting perimeter of the negative pressure suction device constructed from a substantially flexible material which conforms to variations in anatomy, and which deflects to form a substantial seal when placed in contact with the pericardium and activated by a negative pressure suction force.
• Subsequent to securing the desired position and orientation of the beating heart through retraction of the pericardium tissue, coronary artery revascularization may be achieved by locally immobilizing a small portion of the beating heart around the target artery requiring the bypass graft through a variety of ways. One such method consists of immobilizing the portion of beating heart around the target artery through the application of a mechanical compression by virtue of a coronary stabilizer. The remaining portions of the heart continue to beat while the target artery site is immobilized during the bypass graft procedure. One such surgical apparatus for achieving this method of mechanical immobilization has been described in copending Canadian patent application Serial No. 2,216,893 filed on Sep. 30, 1997 in the names of Cartier and Paolitto and entitled “Sternum Retractor for Performing Bypass Surgery on a Beating Heart”. Alternatively, a negative pressure suction has also been used in beating heart CABG to locally immobilize a portion of the beating heart surface in the vicinity of the target artery requiring the bypass graft. An associated device which applies the suction force to the beating heart surface is subsequently secured relative to a stable platform. In this case, the suction port or the structural members of the associated device that applies the negative pressure force must be substantially rigid since the primary purpose of the device is to attempt to immobilize and render motionless that portion of heart tissue it engages in order to create a stable surgical field, while the rest of the heart continues to beat.
• U.S. Pat. No. 5,727,569 issued to Benetti et al. on Mar. 17, 1998 and entitled “Surgical Devices for Imposing a Negative Pressure to Fix the Position of Cardiac Tissue during Surgery”, describes a surgical device for imposing a negative pressure directly on a portion of the outer surface of the beating heart. The Benetti device is applied proximate to or surrounding the portion of the outer surface of the beating heart at which a surgical intervention is to occur. By applying negative pressure by means of the Benetti device, the motion of the outer surface of the beating heart is restricted at the particular area where the surgeon is working. The Benetti reference therefore relates to alleviating the problem of performing extremely delicate surgical procedures, like bypass grafting, during which contractions of the beating heart cause the target artery surface of the heart to move continuously. Benetti et al. teach a method of locally and directly immobilizing the target artery location during a surgical intervention intended to occur within the immobilized region.
• In contrast to the teachings of the prior art, the present invention herein described relates to surgical manipulation of the pericardium, which is the substantially conical membranous sac in which the heart and the commencement of the major vessels are contained. The Benetti reference does not teach or suggest the positioning and orienting of the entire beating heart as a whole, nor is there any teaching or suggestion therein of retraction of the pericardium to achieve surgical access in an area of the beating heart away from where pericardium retraction device is deployed. Rather, Benetti et al. apply suction around or close to the portion of beating heart tissue proximal to the area where the surgical intervention is to be performed. More specifically, the teachings of Benetti et al. result in immobilization of the pulsating effects of a portion of the exterior surface of the beating heart through negative force application at the target artery site. It would be advantageous to be able to position the beating heart through the deployment of the device in a location remote to the desired site of surgical intervention to tend to facilitate the access and approach of surgical instruments, and to tend to improve the ergonomics of the grafting site and direct visibility thereto. Unlike the teachings of the Benetti reference, which results in the application of suction directly on the beating heart, it would instead be advantageous to apply this suction indirectly on a benign, non-beating part of coronary organ tissue. This will tend to not impede, restrain or restrict the function of the beating heart.
• Benetti et al. describe a device with multiple suction ports attached through a negative pressure manifold. In the teachings of Benetti, it is suggested to provide a device having suction ports which share a common negative pressure manifold. However, in such a suggested device, if one suction port is not in contact with underlying tissue to form a seal, then the entire system will tend to be rendered ineffective, at least in part, by the leakage through said port. It would be advantageous to introduce a feature which cuts off flow through non-sealing suction ports with cardiac tissue, thereby tending to maintain effective the entire set-up even if only a portion of the suction ports are properly sealing with the said tissue. Alternatively, Benetti et al. teach that each suction port can have it own independent supply line, which would circumvent this problem through a more complex, cumbersome, and part-intensive set-up. The new invention described herein introduces an embodiment thereof which allows the surgical apparatus, namely the pericardium retraction device, to function with at least a portion of the suction ports in contact with the coronary organ tissue. This embodiment can be applied to other surgical apparatus engaging coronary organ tissue through a negative pressure suction force.
• The Benetti reference describes either fixing the suction port device to a rigid support during the procedure, or having the suction port device as a part of a hand-held instrument with a handle structure connected thereto and adapted to being grasped by a human hand. In contrast to the teachings and suggestions of the Benetti reference, it may be advantageous to attach a suction port device to an intermediate positioning means prior to fixturing the complement to a stable surgical platform such as a sternum retractor, in order to achieve flexibility in the surgical set-up to attempt to cater said surgical set-up to distinct patient anatomies.
• According to the Benetti teachings, the negative pressure suction is the only input means for activating the device to engage the underlying beating heart tissue. If the suction is lost, the loss will lead to the surgical work-site of the beating heart no longer immobilized and resulting instability from pulsating effects. If other instruments are in contact with the heart at this time, it may also lead to risk of trauma or injury.
• In the pericardium retraction device according to the present invention, it would be advantageous to have a design feature in the tissue-engaging member that is activated by the negative pressure suction therein, whereby said design feature comes into contact with a portion of the engaged pericardium tissue and is capable of transmitting a mechanical force to the pericardium tissue being retracted. It would be a further advantage if this said mechanical force remains as a back-up feature in the eventuality that the suction force is interrupted or lost. The embodiment of the invention described herein can be applied to all other surgical apparatus engaging coronary organ tissue.
• In “verticalizing” the beating heart through retraction of pericardium tissue, it may be advantageous in some instances to incorporate in the pericardium retraction device a bracing member which engages on the apex of the “verticalized” beating heart, and thereby tends to facilitate in-process re-adjustments of the position and orientation of the entire beating heart by the movement of the surgical apparatus comprising the pericardium retraction device together with the apex-bracing member.
• In light of the foregoing it would therefore be advantageous to have a device which acts on a portion of the pericardium tissue, in a location remote to the target artery site where the surgical intervention will take place, to aim to achieve the beating heart manipulations in a least invasive, hemodynamically stable manner, wherein the device would not materially interfere with the normal beating function of the heart. It would be a further advantage if this device would act in an area remote to where the surgical intervention is to occur, thereby tending to improve the surgeon's direct vision and ergonomics of the surgical work-site.
• Although the present invention will focus on cardiac surgery, and more specifically CABG surgery performed directly on a beating heart, the principles and concepts may be applied to other types of surgery or surgical interventions that may benefit from the positioning and orientation of a body organ through the retraction of membrane-like body tissue anatomically attached to the said body organ, and capable of being engaged by a negative pressure suction force.
• It is therefore an object of the present invention to provide a retraction device that allows the indirect manipulation of a beating heart as a whole through the application and maintenance of a tensile load on the non-beating pericardium tissue anatomically attached to beating heart, and where said pericardium tissue is engaged by a negative pressure suction force.
• It is another object of the present invention to engage the non-beating pericardium tissue without piercing therethrough and thereby tending to minimize risk of inducing trauma or damage to organs or tissue behind or adjacent the pericardium.
• It is a further object of the present invention to attempt to facilitate posterior artery grafts on the beating heart through indirect manipulation of the beating heart, such that the undesirable physiological effects associated with direct contact manipulation of the beating heart might be alleviated or avoided.
• It is a further object of the present invention to attempt to position and orient a beating heart as a whole without the necessity of directly contacting the pulsating heart surface and without materially impeding or restricting the natural beating function of the heart, thereby promoting a reduction in the likelihood of producing undesirable physiological effects associated with direct contact manipulation of the beating heart.
• It is another object of the present invention to attempt to position and orient the beating heart indirectly through a device acting at a remote location away from the target work-site on said beating heart where the surgical intervention is to be performed.
• It is an additional object of the present invention to attempt to apply the concepts and principles of the present invention as they relate to beating heart CABG to other suitable types of surgery which may require retraction of membrane-like body tissue engaged through a negative pressure suction force.
SUMMARY OF THE INVENTION
• According to one broad aspect of the present invention, there is provided a surgical apparatus for retraction of tissue, the surgical apparatus comprising a tissue-engaging member for providing on the tissue a negative pressure suction force which is sufficient to retract same, the tissue-engaging member having a deformable skirt for contact with the tissue, the deformable skirt defining a contacting perimeter for substantially air-sealed engagement with the tissue, and wherein a negative pressure plenum is formed within the deformable skirt when the tissue engaging member is operatively connected to a negative pressure source and when the contacting perimeter of the deformable skirt is placed against the tissue in substantially air-sealed engagement therewith.
BRIEF DESCRIPTION OF THE DRAWINGS
• For better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of illustration and not of limitation to the accompanying drawings, which show an apparatus according to the embodiments of the present invention, and in which:
• FIG. 1 is a perspective view of a first embodiment according to the present invention illustrating the deployment of a pericardium retraction device oriented and positioned within a surgical workspace by a positioning means attached to a sternum retractor;
• FIG. 2 is a partially dismantled isometric view of the pericardium retraction device illustrated inFIG. 1;
• FIGS. 3A to3C schematically illustrate various dispositions of a deformable skirt means of a pericardium retraction device according to the first embodiment of the present invention comprised of a substantially circular tissue-engaging perimeter;
• FIGS. 4A to4D illustrate several variants of a tissue ingestion-limiting means of the pericardium retraction device of the first embodiment ofFIGS. 1 and 2;
• FIG. 5 is a perspective view of a pericardium retraction device according to a second embodiment of the present invention comprised of a plurality of tissue engaging members in the form of suction ports;
• FIG. 6 is an exploded view of the pericardium retraction device according to the second embodiment of the present invention illustrated inFIG. 5;
• FIG. 7 is a perspective view of the pericardium retraction device according to the second embodiment of the present invention shown inFIG. 5 illustrating the engagement of the pericardium retraction device with pericardium tissue;
• FIGS. 8A to8D illustrate several variants of tissue-grasping means of the tissue-engaging member of the second embodiment ofFIG. 5;
• FIG. 9A is a perspective, cross-sectional view illustrating a pericardium retraction device according to a third embodiment of the present invention comprising a valve means shown in a closed, non-deployed state;
• FIG. 9B is a perspective, cross-sectional view illustrating a pericardium retraction device according to the third embodiment ofFIG. 9A with the valve means shown in an open, deployed state;
• FIG. 10 is a perspective, elevational view of a pericardium retraction device according to a fourth embodiment of the present invention comprising a bracing member engaged with the apex of a beating heart;
• FIG. 11 is an exploded view of the pericardium retraction device and associated bracing member according to the fourth embodiment of the present invention illustrated inFIG. 10;
• FIGS. 12A to12D illustrate several variants of the apex-contacting member of the bracing member according to the fourth embodiment of the present invention illustrated inFIGS. 10 and 11;
• FIG. 13 is a perspective view of a pericardium retraction device according to a fifth embodiment of the present invention, comprising a plurality of independent tissue-engaging members;
• FIG. 14 is a perspective view of a pericardium retraction device according to a sixth embodiment of the present invention, comprising a plurality of independent tissue-clamping members;
• FIG. 15 is a cross-sectional, elevational view of a pericardium retraction device according to a seventh embodiment of the present invention, comprising a conduit means which is provided through a member of the positioning means.
DETAILED DESCRIPTION OF THE INVENTION
• The features and principles of this invention can be applied, in whole or in part, to other types of cardiac surgery requiring the strategic positioning and orientation of a beating heart as a whole organ. By way of illustration, the description of the embodiments that follows herebelow will however focus on applying the features and principles to beating heart CABG surgery.
• In part, the embodiments of this invention may advantageously be applied, if desired, to the surgical retractor and positioning means described in above-referenced copending Canadian patent application Serial No. 2,216,893, the contents of which are incorporated herein by reference. This existing application has been assigned to CORONEO Inc., the assignee of the present application. Alternatively, the embodiments of the invention may also be applied to other types of surgical retractors and other types of positioning means capable of securing the pericardium retraction device according to the present invention in a substantially stable orientation and position relative to the surgical retractor. Alternatively, the surgical retractor may be replaced by other substantially stable surgical platforms that may be engaged with the positioning means to secure the pericardium retraction device according to the present invention. Such surgical platforms would include: a surgical table, a surgical bridge or truss or truss member attached to a surgical table and spanning the patient or set adjacent to the patient, or other like platforms.
• During the course of a cardiac surgery, a surgeon needs to perform certain tasks within a surgical workspace (labelled “W” inFIG. 1). This workspace W is defined by an area that contains generally the perimeter of a deployed sternum retractor and a buffer zone therebeyond, with the area extending below generally to the depth of the patient's thorax, and above generally to the height above the retracted chest cavity in which the surgical apparatus is contained and manipulated.
• By way of a general overview and with reference toFIG. 1, a surgical apparatus with which the invention may be used is comprised of three main components, a pericardium retraction device1, a positioning means such as positioning andarticulation mechanism20 and asternum retractor2. Thesternum retractor2 is illustrated in its deployed state, thereby creating and maintaining the surgical window that provides the surgeon with access to the patient's internal coronary organs, which include the heart, the pericardium tissue, the aorta and vena cava, the coronary arteries and veins, the pleurae, the thymus, and other anatomical features.
• Thesternum retractor2 includes four major parts: (i) anelongated rack bar5, (ii) a firstretractor spreader arm3 being preferably fixed to therack bar5, (iii) a secondretractor spreader arm4 being preferably movable with respect to therack bar5, and (iv) anactuator6 for effecting movement of theretractor spreader arm4 relative toretractor spreader arm3.
• Retractor spreader arms3 and4 extend in a direction substantially transversely with regard to therack bar5, generally in the same direction therefrom and in a parallel orientation with respect to one another. Themovable arm4 can be displaced along therack bar5, and relative to theother arm3, preferably through the rotation of theactuator6 activated by the surgeon. Theactuator6 is operatively connected to therack bar5 and to theother spreader arm4, and is translatable along the length of therack bar5. This is preferably achieved by the engagement of a pinion mechanism (not shown) ofactuator6 with the rack teeth onrack bar5. Tworetractor blades7 and8 are respectively provided with theretractor spreader arms3 and4, preferably disposed below therack bar5 when thesternum retractor2 is deployed on a patient. Theretractor blades7 and8 engage with and serve to retract a portion of the patient's incised skin, the two halves of the patient's incised sternum and the patient's ribcage thereby exposing the coronary organs to be operated on through the resultant surgical window. When viewing the resultant surgical window from above the patient, theretractor arms3 and4 of the deployedsternum retractor2 each have a generally arcuate orientation.
• Thesternum retractor2 advantageously comprisesarcuate rails70 and80 along the top of arcuateretractor spreader arms3 and4, respectively. Therails70 and80 configure an inverted T-slotarcuate passage71 and81, respectively, preferably centrally located within said rails, and preferably extending throughout the entire arcuate length of said rails. A similar linearlongitudinal rail50, may also be configured along the top ofrack bar5.Longitudinal rail50 is also configured with an inverted T-slotlongitudinal passage51, preferably extending throughout its entire longitudinal length. These said rails form a mounting perimeter that can advantageously serve to engage a positioning andarticulation mechanism20 that may be utilized to place a variety of mechanical coronary stabilizers during beating heart CABG surgery, for instance, as described in previously mentioned Canadian application Serial No. 2,216,893. Alternatively, the positioning andarticulation mechanism20 may also be utilized to set a pericardium retraction device1 in a substantially stable position and orientation within the surgical workspace W. As well, these rails can also be utilized to engage other surgical apparatus, that may need to be secured along the perimeter of thesternum retractor2 during cardiac surgery.
• A plurality of slit-like channels72 and82 are configured along thearcuate arms3 and4 and cut through thearcuate rails70 and80, respectively.FIG. 1 illustrates three such slit-like channels72 on theretractor spreader arm3 and three such slit-like channels82 on theretractor spreader arm4. The slit-like channels72 and82 extend downwards from the top of therails70 and80 to a depth preferably below the entire depth of the inverted T-slotarcuate passages71 and81, preferably by an amount equivalent to the width of said slit-like channel. The slit-like channels72 and82 in the present invention are configured so that a wire-like filament will not restrict or otherwise hinder the functionality of the positioning andarticulation mechanism20 when such mechanism becomes engaged in saidpassages71 and81 of saidrails70 and80, provided the wire-like filament is placed in the deepest position within said slit-like channel, as is the case in some of the embodiments of the present invention to be described in greater detail below.
• As further illustrated inFIG. 2, the first embodiment of a pericardium retraction device1 according to the present invention is comprised mainly of a tissue-engagingmember30, a device manipulating means such asshaft member13, a conduit means such asconduit passage10, and a suction line interface means such aspneumatic fitting11. The tissue-engagingmember30 is of a substantially arcuate shape when viewed along the longitudinal axis ofshaft member13. It is further comprised of a substantially-elastic sheath31 serving as an outer shell that is insertable over a substantially-rigidinner structure32.Inner structure32 is substantially air permeable. For instance the inner structure may be designed and produced with an open configuration structure, such as a perforated sheet structure or a truss-like space frame structure.Inner structure32 is rigidly attached at one side thereof toshaft member13 in the vicinity ofsource orifice14, in either a permanent or demountable assembly. At another side thereof,inner structure32 is capped by a substantially planar tissue ingestion-limiting means such as ingestion-limitingbaffle33. Ingestion-limitingbaffle33 is also of a substantially rigid and substantially open configuration.
• Sheath31 is configured with a cut-out slot317 that allows it to slide overpneumatic fitting11 andshaft member13, prior to fitting overinner structure32. The cut-out slot317 must be sufficient to allow insertion over any protrusions, such as manipulation handle12 while stretching theelastic sheath31, if necessary to facilitate insertion.
• The proximal end of theshaft member13 is configured with apneumatic fitting11 which will allow hook-up to a negative pressure source, such as commonly available in most operating rooms. In this first embodiment, theshaft member13 is substantially tubular thereby configuring anintegral conduit passage10 which serves to communicate the proximalpneumatic fitting11 with the distal tissue-engagingmember30. This tends to result in an unencumbered, more ergonomic surgical workspace W, free from connections to peripheral conduits and equipment that may otherwise be disposed in the vicinity of the surgical intervention site. Alternatively, theconduit passage10 may be a separate tubular line either housed inside at least a portion of theshaft member13, or running alongside at least a portion of the said shaft member.
• During multiple vessel beating heart CABG, the pericardium sac is incised usually along the anterior surface of the beating heart and along the long axis of the heart. The pericardium tissue is subsequently unraveled from the surface of the beating heart to expose at least a portion of the beating heart that will undergo the bypass graft surgical intervention. More specifically, during coronary artery revascularization of an inferior or posterior artery such as the circumflex artery (Cx), posterior descending artery (PDA), obtuse marginal artery (OM), or postero-lateral artery (PLA), the surgeon or assistant will position the pericardium retraction device1 in a manner that engages the tissue-engagingperimeter311 thereof with a portion of the pericardium tissue. During the coronary revascularization of these above mentioned arteries, it is preferable to engage the pericardium retraction device1 with the side of the pericardium tissue that was in contact with the heart surface prior to the incision of said tissue, and also preferable to engage pericardium retraction device1 at a location approximately 1.5 inches away from the interface where the pericardium tissue is anatomically attached to the beating heart and the major vessels. A tissue-engagingmember30 with a substantially arcuate shape is advantageous for engaging the pericardium tissue along this said interface.
• With suction introduced, a negative pressure plenum is formed by theinside surface312 ofsheath31 and the top of the pericardium tissue that is engaged within the tissue-engagingperimeter311 of said sheath. A substantial seal between the outer shell formed byelastic sheath31 and the top surface of the pericardium tissue alongperimeter311, and another substantial seal between the said sheath andinner structure32 along cut-out317, render said negative pressure plenum as non-flowing whereby the airflow through tissue-engagingmember30 is temporarily interrupted by its engagement with the pericardium tissue. The suction force exerted through the tissue-engagingmember30 serves to engage the pericardium tissue, but also to adhere theinner surface312 of theelastic sheath31 against the rigid open configuration surfaces ofinner structure32. At least oneconduit passage10 must be in communication with said non-flowing negative pressure plenum to supply suction force to engaged pericardium tissue.
• In this first embodiment,elastic sheath31 may be produced from any suitable polymeric material approved for surgical use. Depending on the polymeric material selected, theelastic sheath31 may be disposable thereby tending to facilitate the cleaning and sterilization of underlyinginner structures32 and33 which preferably form a reusable assembly. Alternatively, theelastic sheath31 may be reusable provided the sheath's polymeric material properties are well-suited to and do not degrade after repeated sterilization cycles. Alternatively, if the polymeric material properties degrade after several sterilization cycles thesheath31 may be replaced at regular intervals after a certain number of surgeries.
• Sheath31 may be designed to have variable elastic properties throughout its shape either by virtue of its variable thickness or by virtue of its variable composition during fabrication. Reinforcement fibers may also be used in the fabrication of thepolymeric sheath31 to bias its elasticity along certain axes. This is especially beneficial where theinner structure32 andshaft member13 are rigid, wherebyelastic sheath31 acts as a buffer in elastic gradient between saidrigid members32 and13 and non-structural membrane-like pericardium tissue. This buffer in elastic gradient may encourage the membrane-like pericardium tissue to remain in compliant contact with tissue-engagingperimeter311 of said sheath.
• Oncesheath31 is fully assembled overinner structure32, the tissue-engagingperimeter311 extends outwardly beyond theinner structure perimeter321. This flexible and substantially elastic protrusion tends to provide flexibility in the design to cater to different patient anatomies and to assist with some degree of ingestion of the pericardium tissue by thetissue engaging member31 regardless of variations in anatomy. Ingestion of the pericardium tissue is discussed in greater detail below.
• The open area perimeter ofsheath31 is configured with a tapered and beveled terminal edge in the nature of adeformable skirt316, as best shown inFIGS. 2 and 15. Extending outwardly beyondinner structure perimeter321, thisdeformable skirt316 achieves a substantially compliant seal perimeter at tissue-engagingperimeter311, capable of engaging the pericardium tissue throughout a range of spatial orientations which the pericardium tissue may assume relative toinner structure32. Thedeformable skirt316 provides readjustment of the substantially planar surface formed by tissue-engagingperimeter311 depending on the direction of application of tensile retraction loads applied to and reacted by the pericardium tissue. A tensile retraction load applied to the pericardium tissue in a direction substantially parallel to the axis ofshaft member13 distorts the beveled edge ofdeformable skirt316 equally around the tissue-engagingperimeter311, in an inward direction toward the center of said tissue-engagingperimeter311. If the tensile retraction load is applied to the pericardium tissue in a skewed direction relative to the axis ofshaft member13, the beveled edge ofskirt316 will distort unevenly around the tissue-engagingperimeter311 in a fashion that the substantially planar surface formed by tissue-engagingperimeter311 is now oriented substantially perpendicular to the direction of application of said manipulation force or substantially perpendicular to the pericardium reaction force to imposed retraction loads. This is better illustrated inFIGS. 3A-3C, and explained in this case with a single tissue-engaging member such assuction port34 which has substantially circular tissue-engagingperimeter341. Apart from the cross-sectional shape of thesuction port34, it generally provides a construction similar to that oftissue engaging member30. By virtue of thedeformable skirt342, the substantially planar surface formed bytissue engaging perimeter341 engaged with pericardium tissue may assume a virtually infinite number of spatial orientations. These spatial orientations may be defined by a vector (not shown) that passes through the center ofperimeter341 and is normal to the substantially planar surface formed by saidperimeter341 lying within a substantially conical volume of angle φ (not shown) relative to the centerline ofsuction port34.
• The ingestion-limitingbaffle33 illustrated inFIG. 2, ensures that the pericardium tissue will not be entirely ingested within inner structure32 (if said baffle is not present), but ingested the optimum amount to regulate the suction forces on the engaged pericardium tissue derived from negative pressure acting thereon. Since thesource orifice14 for the negative pressure is typically much smaller in area than the area required to achieve the desired suction force through tissue-engagingmember30, the ingestion-limitingbaffle33 serves to ensure the suction force reacts on a much larger area of pericardium tissue. The structural integrity of the ingestion-limitingbaffle33, combined with theinner structure32, ensure thestructural perimeter321 remains open to maintain the desired suction force. Furthermore,structural perimeter321 must remain substantially rigid to keepelastic sheath31 from rippling along itstissue engaging perimeter311 due to the effect of the negative pressure suction. This rippling would tend to render more difficult the compliance of the pericardium to thetissue engaging perimeter311, since such tissue would be required to conform to the irregular shape of the rippled perimeter. The pericardium tissue is partially ingested within tissue-engagingmember30 by an amount substantially equal to the extension of tissue-engagingperimeter311 ofsheath31 beyondstructural perimeter321 ofinner structure32. The ingested pericardium tissue contacts the ingestion-limiting baffle and assumes a shape conforming to the shape of the said baffle.
• The tissue ingestion-limitingbaffle33 preferably forms an integral assembly with the openinternal structure32, whereby it may be demountably assembled with mechanical fasteners or by virtue of a clipped-in assembly, or it may be permanently mounted by gluing, welding, brazing, or other like means alongperimeter321. Alternatively, the tissue ingestion-limiting means may be part ofelastic sheath31, for instance finger-like protrusions extending frominner surface312 in a direction normal thereto.
• Variations in the open configuration of ingestion-limitingbaffle33 are illustrated inFIGS. 4A-4D.FIG. 4A illustrates an ingestion-limiting baffle with substantiallycircular perforations331,FIG. 4B illustrates a baffle with webs defined by substantiallytriangular perforations332,FIG. 4C illustrates a baffle with webs defined by substantiallysquare perforations333, andFIG. 4D a baffle with webs defined by substantiallyrectangular perforations334. Other like open configurations for the tissue-ingestion baffle are possible without departing from the spirit of the present invention. As those skilled in this art will appreciate, the resulting suction force on the engaged pericardium is partly a function of the open area throughbaffle33 based on its perforation density.
• The substantially open configurationinner structure32 may be configured with the same variations in construction as the tissue ingestion-limitingbaffle33, that is, webs defined from a variety of perforations.
• Theshaft member13 is may comprise amanipulation handle12 for the surgeon to manipulate, orient, and position the pericardium retraction device1. The desired verticalization of the beating heart is achieved by the application of a tensile load to the pericardium tissue by the surgeon's manipulation of the pericardium retraction device1 that is engaged with a portion of pericardium tissue by virtue of a negative pressure suction force. Heart verticalization is achieved in an indirect manner whereby the beating heart is not in direct contact with the enabling surgical apparatus in the nature of a pericardium retraction device. Moreover, the pericardium retraction loads tend not to impose any considerable restriction on the beating function of the heart thereby increasing the likelihood of achieving hemodynamically stable beating heart manipulations.
• The desired pericardium retraction load or the desired heart verticalization is maintained by securing the pericardium retraction device1 to thesternum retractor2 through the positioning andarticulation mechanism20. The positioning andarticulation mechanism20 is preferably comprised of a first joining member such as a first articulation member in the nature of acylindrical post21 and a second joining member such as a second articulation member in the nature of aspherical clamp22, each capable of providing a multitude of motion degrees of freedom.Shaft member13 is inserted in between the clamping members ofspherical clamp22. The clamping members may engage theshaft member13 anywhere along its longitudinal length. Final adjustments to the pericardium retraction load may also occur with theshaft member13 engaged between clamping members ofspherical clamp22 before the entire positioning andarticulation mechanism20 assembly is rigidly secured through the action of each of the tensioning knobs ofspherical clamp22 andcylindrical post21.
• In-process readjustments to the pericardium retraction load may also occur by loosening one or both of each said tensioning knobs, and not disengaging the pericardium retraction device1 from thespherical clamp22. With the tensioning knob ofspherical clamp22 slightly loosened, the pericardium retraction device1 is free to translate through the clamping members ofspherical clamp22, rotate about the axis of shaft means13, pivot about axis ofrod23, and articulate angularly within a plane formed by the centerlines ofarticulation rod23 andshaft member13. With the tensioning knob ofcylindrical post21 loosened,articulation rod23 is free to rotate about its longitudinal axis, is free to translate through thecylindrical post21 in a direction along its longitudinal axis, is free to articulate into and out of the retracted chest cavity by increasing or decreasing the angle between its longitudinal axis and the centerline axis ofcylindrical post21, is free to rotate about the centerline axiscylindrical post21, and is free to slide within arcuate passage81 (or either of thearcuate passages71 and51). These motion degrees of freedom provide the mechanical flexibility to tailor the surgical set-up to distinct patient anatomies tending to result in an ergonomic deployment of the pericardium retraction device.Cylindrical post21 is preferably already installed with thefirst articulation rod23 on the perimeter rail80 (or perimeter rails70 or50) ofsternum retractor2 prior to engaging the pericardium tissue with the pericardium retraction device1. The positioning andarticulation mechanism20 serves to set the pericardium retraction device1, in virtually any substantially stable position and orientation within surgical workspace W and relative to asternum retractor2. A suitable positioning and articulation mechanism which may advantageously be used with the pericardium retraction device of the present invention is disclosed in the above-mentioned Canadian patent application Serial No. 2,216,893, whose specification is incorporated herein by reference.
• In this first embodiment, the tissue-engagingmember30 forms an arcuate opening for engaging the pericardium tissue. Alternatively, the tissue-engagingperimeter311 can be configured on thefront face314 ofelastic sheath31, therear face315, or any combination thereof.
• Shaft member13 is rigidly attached to the top portion ofinner structure32 in preferably a substantially perpendicular orientation relative to a plane containing the arcuate spine defining saidinner structure32. Alternatively, the orientation ofshaft member13 relative to inner structure may be varied to include other orientations. As well, a hinge joint or spherical joint may be configured at the junction betweenshaft member13 andinner structure32 to result in a variable angle orientation between saidcomponents13 and32 depending on direction of the application of the pericardium retraction force applied by the surgeon.
• In this first embodiment, theinner structure32 and shaft means13 are manufactured from reusable, sterilizable materials approved for use in surgery, in rigid configurations. These include, but are not limited to, stainless steel, aluminum, nickel, or titanium. Alternatively, theinner structure32 can be designed with stiffness gradient along its defining parameters. For instance, the inner structure can be designed with a variable stiffness along its spine arcuate length in order to tend to more closely comply to the deformed shape of the retracted pericardium tissue. For instance, such a variable stiffness may be defined such that the opposed terminal ends of theinner structure32 are less stiff than the portions thereof which areadjacent shaft member13. This can be achieved through selective geometry, varying density of perforations, variable wall thickness, or by anisotropic material properties, as is achieved in variable composition polymers. Alternatively, this first embodiment may also be a reusable, one piece construction, wherebysheath31 andinner structure32 are replaced by a structural outer skin. The ingestion-limitingbaffle33 is in this case mounted in a recessed position within structural outer skin with respect to the tissue-engagingperimeter311.
• In broad terms, the surgical procedure for the set-up and deployment of the pericardium retraction device1 during a beating heart CABG surgery, and relating to the present invention consists of:
• • (a) performing a full or partial midline sternotomy incision;
  • (b) cauterizing of any bleeding vessels subsequent to the sternotomy incision;
  • (c) if an internal thoracic artery (ITA) will be used as a bypass conduit, retracting the two halves of the patient's incised sternum with a surgical retractor suitable for exposing the ITA and the surgical harvesting thereof,
  • (d) retrieving the surgical retractor used for ITA harvesting, and insertingblades7 and8 ofsternum retractor2 along the sternotomy incision;
  • (e) retracting the patient's ribcage to expose the underlying mediastinum and pericardium tissue;
  • (f) incising the pericardium sac to expose at least a portion of the patient's beating heart requiring the bypass graft;
  • (g) deploying the pericardium retraction device1 by bringing into proximity and in substantial contact with the pericardium tissue (labelled PCT inFIG. 10) the tissue-engagingmember30;
  • (h) introducing a negative pressure suction through pericardium retraction device1;
  • (i) ensuring that a portion of the pericardium tissue is properly ingested within tissue-engagingmember30 and that adequate sealing of negative pressure occurs at theperimeter311 of saidmember30;
  • (j) while graspinghandle12, spatially orienting and positioning the pericardium retraction device1, with engaged portion of pericardium tissue within itsmember30, in a manner to apply a tensile load on the pericardium tissue and thereby simultaneously positioning and orienting the beating heart anatomically attached to said pericardium tissue;
  • (k) maintaining the desired beating heart position and orientation by securing the pericardium retraction device1 tosternum retractor2 through positioning andarticulation mechanism20, resulting in the desired access to the coronary artery bed requiring the bypass graft;
  • (l) to perform bypass grafts on the inferior or posterior coronary artery beds, preferably placing the beating heart in a verticalized position with the longitudinal axis of the heart assuming a substantially vertical orientation through the rotation of the apex of the heart relative to the base of the heart outwardly through the retracted ribcage;
  • (m) with the beating heart in the desired position and orientation to improve surgical access to target coronary artery, deploying a positioning andarticulation mechanism20 and associated mechanical coronary stabilizer according to the above-mentioned copending Canadian patent application Serial No. 2,216,893, or other like positioning and heart contacting means that allow the surgeon to perform a bypass graft on the beating heart;
  • (n) disengaging the mechanical coronary stabilizer, or other like means, from the surface of the beating heart after the completion of the bypass graft;
  • (o) disengaging the pericardium retraction device1 from its positioning andarticulation mechanism20 and easing the beating heart back to its natural position into the chest cavity through the reduction of the tensile load applied through the pericardium retraction device1;
  • (p) turning off the negative pressure suction through the pericardium retraction device1 and retrieving said device1 from retracted chest cavity;
  • (q)Closing retractor arms3 and4 and retrievingsternum retractor2;
  • (r) Closing the midline sternotomy surgical incision.
• The embodiments of the pericardium retraction device that follow and described in more detail below, are deployed and set up in a similar surgical procedure as described above, provided the pericardium tissue is engaged by virtue of a negative pressure suction force.
• FIGS.5 to7 illustrate a second embodiment according to the present invention. The tissue-engagingmember130 of thepericardium retraction device101 is comprised of a plurality of bell-shapedsuction ports36, each demountably attached to a substantially semicirculartubular spine35 through an attachment fitting351. This embodiment illustrates five such ports, which shall be referred to as ports A, B, C, D, and E in a clockwise direction. Thesuction ports36 are described in greater detail below. Thefittings351 are preferably arranged such that their centerlines are substantially parallel to the centerline defining the semicirculartubular spine35. Alternative embodiments may haveattachment fittings351, and consequentlysuction ports36, attached tospine35 in a variety of orientations or combination of orientations. For example, ports A, C, and E may be configured with centerlines substantially parallel to the centerline definingsemicircular spine35, and ports B and D may be configured with centerlines substantially perpendicular to the centerlines of ports A, C, and E whereby said ports extend radially outward away from the center ofsemicircular spine35.
• Conduit passage10 serves to communicate the negative pressure suction from apneumatic fitting11 at the proximal end of thepericardium retraction device101 to the arcuate manifold passage355 (FIG. 6) within semicirculartubular spine35.Semicircular spine35 serves as a manifold to communicate the negative pressure suction to each of thesuction ports36 through a series of inlet orifices in each of the attachment fitting351.Orifice140 through each of thesuction ports36 comes into sealed contact with the inlet orifice in attachment fitting351 when saidsuction port36 engages saidspine35 through said fitting351.
• Spine35 is attached to the distal end ofshaft member13.Gusset plates354 or the like may serve to reinforce the structural joint betweenspine35 andshaft member13. One attachment fitting351 is positioned in line with the centerline ofshaft member13 in order to facilitate cleaning prior to sterilization of theintegral conduit passage10 withinshaft member13.Endplugs352 are also provided at the arc ends ofspine35 to facilitate cleaning prior to sterilization of thearcuate manifold passage355. Thesuction ports36 are preferably manufactured from an elastic polymeric material, safe for surgical use. If the polymeric material is not suitable for repeated sterilization cycles, thesuction ports36 will be disposable elements and hence the need for a demountable assembly torigid spine35. Alternatively, if entirepericardium retraction device101 is made to be disposable, the interface between thesuction ports36 andspine35 may be a permanent junction.
• Each of theattachment fittings351 is embodied with anattachment feature353, in this case an internal double start thread, which interfaces with theattachment feature369 onsuction port36, in this case an external double start thread (FIG. 6). Alternative attachment features to securesuction ports36 to thespine35 may include: a snap-in ridge-in-groove arrangement, a retaining ring, a spring detent feature engaging a retention groove, a flanged suction port laterally engaging a groove feature (tongue and groove arrangement), a hinged clamping flange, a partial-turn drum cam interface, and a “peel and expose” temporary adhesive. This latter “peel and expose” temporary adhesive may be such that it degenerates during post-surgery sterilization cycle, thereby releasing the usedsuction port36 from attachment fitting351 ready to receive a new pre-packaged,pre-sterilized suction port36 with also with a said “peel and expose” adhesive.
• FIG. 7 illustrates the tissue-engagingmember130 with the plurality ofdeformable suction ports36 in their deployed shape after each has engaged a portion of the pericardium tissue. Each of thedeformable suction ports36 is comprised of anorifice140, anattachment feature369, a tissue-graspingmeans363, a tissue-engagingperimeter361, and at least onedeformation bias362 disposed preferably along saidperimeter361.
• In deploying thepericardium retraction device101 according to this second embodiment, while the negative pressure suction is introduced through the pericardium retraction device, the surgeon first contacts a portion of pericardium tissue with theengaging perimeter361 of each of thesuction ports36. A substantial seal results about saidperimeter361 of each of the suction ports. A portion of pericardium tissue is ingested within the inside surface of each of thesuction ports36. The seal formed at theperimeter361 of eachsuction port36 and the resultant suction force on the engaged pericardium tissue within each said perimeter, causes thedeformable suction port36 to deform along itsbias362. Folding ofsuction port36 along the bias362 (or the collapsing of the opposingsuction port36 internal surfaces substantially towards one another) sets the tissue-graspingmeans363 oninside surface360 in contact with the ingested pericardium tissue. Thedeformation bias362 may be a notch (FIGS. 8A through 8D) or other like means which will promote a localized folding action and resulting partial collapse of the sidewalls of thesuction port36 when such sidewalls are subjected to radial loading due to the effect of suction.
• As the surgeon manipulates theretraction device101 to position and orient the beating heart, the tensile load on the pericardium tissue increases due to the imposed retraction loads. Any expelling action of the engaged portion of pericardium tissue by virtue of the increasing retraction loads on the pericardium tissue, will engage the tissue-graspingmeans363 deeper into the portion of ingested pericardium tissue. Consequently, the retraction of the pericardium tissue may be provided through a combination of negative pressure suction force and a resulting mechanical grasping occurring between theinside surface360 ofsuction port36 and ingested pericardium tissue by virtue of the graspingmeans363. The tissue-graspingmeans363 therefore may be capable of maintaining at least a limited retraction load if the negative pressure suction force is temporarily interrupted or disabled. If it is desired to promote this effect of mechanical grasping in the absence of a negative pressure suction force, the tissue grasping means are preferably in the form of protrusions which extend generally radially towards the center of theengaging perimeter361 and more preferably, also generally away from the direction in which the pericardium tissue will retract if the tensile load placed thereon is released. In this manner, continued engagement of the grasping means may be promoted when a tensile load is maintained on the pericardium tissue, even in the event that the suction force acting thereon may be temporarily interrupted or disabled. However, once the tensile load is relieved, for instance by a surgeon manipulating the pericardium retraction device in a direction towards the patient's thoracic cavity, it is expected that the tissue grasping means will thereafter disengage from the pericardium tissue once the suction force is absent. Tissue grasping means in the form of protrusions are described below with reference toFIG. 8A. Other tissue grasping means are described below with reference toFIGS. 8B to8D.
• The negative pressure suction force is therefore in a sense the catalyst for inducing the engagement of tissue-graspingmeans363 with ingested pericardium tissue withinsuction port36. Thepericardium retraction device101 is positioned and secured within the surgical workspace W through the positioning andarticulation mechanism20 and thesternum retractor2 in the same manner as the first embodiment. When the surgical intervention on the “verticalized” beating heart is completed, thepericardium retraction device101 is displaced from its retraction-inducing setting to a position within the surgical workspace that relieves the tensile load on the pericardium tissue, thereby also displacing the beating heart to its natural position within the chest cavity. When the negative pressure suction is turned off and the tensile load on the pericardium tissue is relieved, thedeformable suction port31 resumes its original free state, the tissue-graspingmeans363 substantially disengages pericardium tissue, and the pericardium retraction device may be retrieved.
• The tissue-graspingmeans363 is disposed along at least a portion of theinside surface360 of thesuction port36, preferably along portions of said inside surface which will be brought into opposition whensuction port36 deforms according to itsbias362. The tissue-graspingmeans363 is a surface treatment which promotes its adherence to the ingested pericardium tissue. Several variants of the tissue-graspingmeans363 are possible.FIG. 8A illustrates a tissue-grasping means comprised of pedestal-like or pin-like protrusions364;FIG. 8B illustrates a tissue-grasping means comprised of a grid-like matrix365;FIG. 8C illustrates a tissue-grasping means comprised of a ridged formation such as a step-like or groove-like perimeter366; andFIG. 8D illustrates a tissue-grasping means comprised of a tissue adhesive-like coating orlayer367, for instance a hydrogel coating.
• The tissue-graspingmeans363 may be a resultant feature from the manufacturing process which producessuction port36. Alternatively, the tissue-grasping means may be or a feature that is introduced during a subsequent fabrication process, such as during assembly injection molding. For example, the tissue-grasping means may be injection molded onto thesurface360 subsequent to the injection molding ofsuction port36. Alternatively, the tissue-grasping means may be a separate distinct feature-part, permanently attached or demountably attached toinside surface360 ofsuction port36. For example, a separate flexible metal foil layer glued on theinside surface360 ofsuction port36, protruding metal pins embedded intoinside surface360 ofsuction port36.
• Other variations of the second embodiment without departing from the spirit of the present invention are possible. Alternatively, instead of a manifold arrangement, eachsuction port36 may be fed by its own designatedconduit passage10.
• Alternatively, thepneumatic fitting11 may be incorporated withspine35 at one of the arc end locations thereby replacing one of theend fittings352.
• Alternatively, the semicirculartubular spine35 may be of a substantially linear shape or a substantially S-shaped inflected curve shape.
• Thesuction port36 may be produced from a polymeric material with variable composition and elasticity in at least a portion of its shape, in order to cater its material properties to the desired function at that specific location. For example, asuction port36 may be produced with substantiallyrigid attachment feature369 and substantially rigid protrusions defining its tissue-graspingmeans363, but with substantially flexible and compliant tissue-engagingperimeter361.
• Alternatively,suction port36 may have more than onebias362 along itsperimeter361 encouraging the desired deformed shape ofsuction port36 that will set the tissue-graspingmeans363 in contact with the ingested pericardium tissue.
• Alternatively, the shape of the contactingperimeter361 may be substantially oval, substantially lens shaped, or substantially circular. Other shapes for the contactingperimeter361 may also be suitable, as those skilled in this art will appreciate.
• FIGS. 9A and 9B illustrates a third embodiment according to the present invention. The third embodiment comprises, through the provision of a valve means380, a substantially self-sealing tissue-engagingmember38 such that the flow through thepericardium retraction device103 is substantially zero even if the negative pressure plenum is not completed by the pericardium tissue in contact with theperimeter384, as is the requirement in the previous embodiments.
• This is advantageous in pericardium retraction devices comprised of a plurality of tissue-engaging members, when not all tissue-engaging members or suction ports are, or can be, in sealing contact with the pericardium tissue. Without a valve means380, the excessive flow through a non sealing suction port would tend to render ineffective the remaining suction ports as well, due to the inability to generate the desired negative pressure and consequently suction force. Alternatively to incorporating a valve means, this problem can be alleviated by incorporating a designated conduit means10 for each suction port. This tends to result in a more complex, part-intensive, and consequently more costly apparatus.
• In this third embodiment, the tissue-engagingmember38 is comprised of ahollow attachment feature388, asource orifice141, adiaphragm member387, and a spool valve means380. Thehollow attachment feature388 serves to fixture said tissue-engagingmember38 to a substantially rigid tubular spine (like35) in a plurality arrangement, or directly to ashaft member13 in a single port arrangement. Thesource orifice141 serves to communicate with the negative pressure source P2 through tubular spine (like35) andconduit member10. Thediaphragm member387 delimits a negative pressure plenum within tissue-engagingmember38.
• The spool valve means380 may assume either a “valve closed” position in which the negative pressure plenum P2 is delimited bydiaphragm member387, as illustrated inFIG. 9A, or an “open valve” position in which the negative pressure plenum is delimited by the engaged pericardium alongperimeter384, and as illustrated inFIG. 9B, the substantially ambient pressure P1 drops to negative source pressure P2.
• The top surface of tissue-engagingmember38 and thediaphragm member387 each are provided with a guiding and sealingbore feature385 and386 respectively, which serve to guide the spool valve means380 throughout its travel within the tissue-engagingmember38, and also provide a substantial seal with theshaft383.
• Valve means380 is comprised of a dish-like plunger381 which has a slot-like feature382 to communicate plenum P2 with plenum P1 whenshaft383 is plunged by the engagement of pericardium tissue aroundperimeter384. When the pericardium tissue is not in contact withplunger381, the valve means380 assumes a stable position within the tissue-engagingmember38 due to a pressure balance, whereby top edge slot-like feature382 is just cutting off flow through thediaphragm member387. At the “valve closed” position, theplunger381 is substantially proud (by a distance δ) from the tissue-engagingperimeter384, and ready to engage the pericardium tissue.
• Plunger381 is configured with a dish-like shape in order to easily contact the pericardium tissue in a non-traumatic manner, but other shapes are also possible without departing from spirit of the invention. In the “valve open” position, with theplunger381 at its topmost position within tissue-engagingmember38,plunger381 also acts as a tissue ingestion-limiting means.
• A stopper feature (not shown) to limit the translation of valve means380 within tissue-engagingmember38 may also be incorporated. Stopper features may include, a stepped diameter, a key-way feature, a transverse dowel, a retaining ring, and other like limit means disposed at the terminal end of the valve means380 which is opposite theplunger381 thereof and adjacent sealing bore385.
• A spring member (not shown) may also be incorporated to further encourage valve means380 to remain in the non-flowing closed position. Initially, this spring load exerted by this said spring member must be overcome by the action of engaging pericardium tissue to plunge open the valve means380. This said spring load must also be overcome throughout the deployment of thepericardium retraction device103 by the resultant suction force acting on the engaged pericardium tissue.
• Alternatively, instead of mechanical actuation of valve means380 through the travel ofplunger381, the valve means may be electronically actuated by a proximity sensor which senses the position of the underlying pericardium tissue when said tissue is in proximity to tissue-engagingmember38. The proximity sensor may be designed utilizing a light source, an electromagnetic field, or a heat measurement transducer, to name a few examples.
• Alternatively, the concepts of this third embodiment can also be applied to other tissue-engaging members that engage other types of coronary tissue or body tissues in general, and are not limited to engaging pericardium tissue.
• The fourth embodiment according to the present invention, introduces an organ bracing member such as a heart apex-bracingmechanism90, which may be deployed in conjunction with apericardium retraction device100. The “verticalized” beating heart (labelled VBH inFIG. 10) and the pericardium tissue (labelled PCT inFIG. 10) anatomically attached to said beating heart are illustrated engaged with the apex-bracingmechanism90 and thepericardium retraction device100, respectively. Thepericardium retraction device100 according to the present invention is comprised mainly of a tissue-engagingmember30, a device manipulating means such asshaft member113, a conduit means such asconduit passage110, and a suction line interface means such aspneumatic fitting11. The tissue-engagingmember30 has already been described in the first embodiment. Alternatively, other tissue-engaging members from other previous embodiments may also be substituted in place of tissue-engagingmember30.
• As previously described, when the beating heart is “verticalized” by way of pericardium tissue retraction, the apex of the heart assumes a substantially protruding orientation outward from the patient's retracted chest cavity. The bracing means, preferably deployed in series after the deployment of the pericardium retraction device, serves as a stability-enhancing measure, which substantially limits the excursion or movement of a portion of the “verticalized” beating heart, preferably the apex. This bracing means may not be desired in all cardiac surgical interventions that are performed with the assistance of the pericardium retraction device.
• As illustrated inFIGS. 10 and 11, the apex-bracingmechanism90 is comprised of an articulation and clampingmember85, a bracing or supportingshaft member92, and a tissue-contacting member such as an apex-contactingmember91. The apex-bracingmechanism90 is engaged with thepericardium retraction device100 through the articulation and clampingmember85 which simultaneously clamps onto the proximal portion ofshaft member13 while securing the desired position and orientation of bracingshaft member92. A negative pressure suction source is introduced through apneumatic fitting11 situated on the proximal end ofextension shaft member113. A conduit passage within extension shaft member113 (not shown) supplies negative pressure to both the pericardium tissue-engagingmember30 throughconduit passage110 inshaft member13, and the apex-contactingmember91 through substantially tubular bracingshaft member92 and a series of passages hereunder described. Consequently, since it may be desired to deploy the apex-contactingmember91 subsequent to the pericardium tissue-engagingmember30, a valve means (like valve means380 in the previous embodiment) is preferably contained within the saidmember91.
• With reference toFIG. 11, from the proximal end ofconduit passage110, the negative pressure supply enters a series of passages in the clamping member86, more specifically into aplenum cavity861 into which the proximal end ofconduit passage110 is received, through an integraltransverse conduit passage866, and through a conduit bore869 which is disposed generally transverse to the axial direction ofconduit passage110. From the clamping member86, the negative pressure supply enters intohollow articulation cylinder95 and through internal passages in bracingshaft member92 and resilientcurved member911 to attain the apex-contactingmember91 which, in this case, serves as a negative pressure suction port. Alternately, the apex contacting means91 can be provided with its own designated negative pressure conduit line.
• To maintain the negative pressure through component interfaces, ajoint seal84 is provided between clamping member86 and the proximal end ofshaft member13 at theplenum cavity861 location. A joint seal94 is also provided betweenarticulation cylinder95 and clamping member86 at the conduit bore869 location. A counterbore (not shown) may be provided with conduit bore869 in order to locate joint seal94 and the contacting perimeter ofarticulation cylinder95.Seal plate867 is provided to coverconduit passage866 and facilitate the machining of said conduit passages within clamping member86. Alternatively,plate867 may be eliminated if clamping member86 is produced as a casting with integral cored conduit passages. Alternatively,extension shaft member113 may be eliminated by extendingshaft member13 through theplenum cavity861.
• The articulation and clampingmember85 is comprised of clampingmember83 and clamping member86. The securing of articulation and clampingmember85 is achieved through a threadedmember87, which is assembled in clamping member86 through retainingpin88 and extends throughbore834 of clampingmember83 to become engaged by tensioningknob850.Shaft member13 is engaged laterally bysurface835 and a like surface (not shown) of clampingmembers83 and86 respectively, and axially on its topmost surface bycavity plenum861. This secures the orientation (rotation) of clampingmember85 and bracingshaft member92 about the centerline ofshaft member13.Articulation cylinder95 is simultaneously clamped betweenengagement surface839 onclamp83 and a like surface on clamp86, thereby securing its articulation position in and out of chest cavity relative toshaft member13 and clampingmember85.
• Bracingshaft member92 is comprised of anarticulation cylinder95 and an interfacejoint member932. As illustrated inFIG. 11, bracingshaft member92 is substantially tubular to integrate internal conduit passage for negative pressure when apex-contactingmember91 is a negative pressure suction port. Bracingshaft member92 may be entirely rigid, or may be deformable only by a surgeon input, or may be a lockable multi-jointed articulated design and construction. In all variants, the saidmember92 is substantially rigid in that it should not yield under the forces imposed on it by the beating heart.
• Apex-contactingmember91 is comprised of a resilientcurved member911 and an interfacejoint member931. Resilientcurved member911 is substantially flexible, since it will elastically yield a limited amount under the forces imposed by the beating heart, depending on its designed stiffness.FIGS. 12A to12D illustrate variants in the apex-contactingmember91.FIG. 12A illustrates an apex-contacting member comprising a substantially conical cup made from a flexiblepolymeric material915;FIG. 12B illustrates an apex-contacting member comprising a plurality of substantially rigid finger-like protrusions916;FIG. 12C illustrates an apex-contacting member comprising a tissue-clamping means917; andFIG. 12D illustrates an apex-contacting member comprising a substantially hemi-cylindrical cradle918 with perforations to allow anchoring to the apex tissue of beating heart with an associated suture919. Additionally, with each of these variants, a tissue-grasping means or hydrogel coating may also be incorporated on the heart contacting surface of the said apex-contacting member, in order to attempt to improve the adherence to the beating heart tissue. Any of the variants ofFIGS. 12A, 12B and12D may be utilized with the provision of a suction force or without.
• The bracingshaft member92 and apex-contactingmember91 are engaged atjunction93, which provides the ability to rotate apex-contactingmember91 about the centerline ofshaft member92. The twointerface members931 and932 comprising the saidjunction93 may be rotatingly engaged through suction, if the apex-contactingmember91 serves as a negative pressure suction port. Alternatively,interface members931 and932 may be rotatingly engaged through a magnetic attraction, through a press-fit allowing relative rotation of said interface members only through torque applied by surgeon's hand but not by loads exerted by the beating heart on said interface members, through a ratchet mechanism between said interface members, or by other like means.
• In another variant of the present embodiment,junction93 may be of a telescopic design to allow the translation, or the translation and rotation of apex-contactingmember91 relative to bracingshaft member92.
• Alternatively, a rotationalinterface replacing junction93 may be incorporated in design of the articulation and clampingmember85. Alternatively, the articulation and clampingmember85 may be designed to allow the translation of bracingshaft member92 along its longitudinal axis through said clampingmember85.
• With reference toFIG. 10, to deploy the apex-bracingmechanism90 the surgeon will preferably first position and orient thepericardium retraction device100 in a similar manner as described in the previous embodiments. Once the beating heart is “verticalized”, and the positioning andarticulation mechanism20 has been secured at botharticulation members21 and22, the apex-bracingmechanism90 is positioned and oriented within the same surgical workspace W, such that the apex-contactingmember91 is in contact with the apex of the beating heart and the articulation and clampingmember85 is engaged with the topmost surface and sides ofshaft member13. This may involve the rotation of the apex-bracingmechanism90 about the centerline ofshaft member13, the articulation of bracingshaft member92 about the centerline ofarticulation cylinder95, and the rotation of apex-contactingmember91 about the centerline of bracingshaft member92. The device is intended to allow for delicate presentation of the apex-bracingmechanism90 preferably onto the apex of a “verticalized” beating heart.
• The entire surgical apparatus assembly consisting of thepericardium retraction device100 and the apex-bracingmechanism90, may also be positioned and oriented within the surgical workspace W by way of adjustment of either of thesecond articulation member22 or thefirst articulation member21, or by way of simultaneous adjustment of both saidarticulation members21 and22. Consequently, the beating heart may be re-oriented and re-positioned through a displacement of both thepericardium retraction device100 and apex-bracingmechanism90.
• Alternatively, clampingmember85 andarticulation member22 may be combined into one mechanical assembly, preferably when the apex-contactingmember91 does not serve as a negative pressure suction port. Clampingmember85 may be replaced with an interface sleeve that is clamped between thesecond articulation member22 andshaft member13.
• Alternatively, in another embodiment, the apex-bracingmechanism90 may be provided with its own designated positioning andarticulation mechanism20, comprising first21 and second22 articulation members, and whereby saidfirst articulation member21 may be slidingly and rotatingly engaged alongrails70,80, or50 of thesternum retractor2, independently from the deployment of thepericardium retraction device100.
• Alternatively, the apex-bracingmechanism90 may also be used exclusively in certain cardiac surgeries, without thepericardium retraction device100.
• FIG. 13 illustrates a fifth embodiment according to the present invention, showing a deployedsurgical retractor2 and deployedpericardium retraction device105. The beating heart and pericardium tissue are not illustrated. Thepericardium retraction device105 is comprised of a tissue-engagingmember39, a device manipulating means in the nature of a wire-like filament393, a conduit means such asflexible conduit15, and a suction line interface means such aspneumatic fitting11. The tissue-engagingmember39 is comprised of a deformable bell-shaped suction port390 (illustrated in its deformed, deployed shape) and an attachment fitting399. Suction port390 is provided with the following main features: a tissue-engagingperimeter391, at least onedeformation bias392 disposed preferably along saidperimeter391, and preferably a tissue-grasping means (not shown) on at least a portion of inside surface (not shown) of port390 which comes into contact with the ingested pericardium tissue. With the exception of wire-like filament393 described below, the suction port390 is of similar construction to thesuction port36 of the second embodiment. The function of said port390 and the cooperation of its constituent features having been previously described by similarity through the description ofsuction port36 in the second embodiment.
• In this embodiment, pericardium tissue is retracted by at least onepericardium retraction device105. The beating heart is preferably “verticalized” by a plurality of tissue-engagingmembers39, each supplied by its own designatedconduit15, and each being secured independently to asternum retractor2 through the anchoring of wire-like filament393. Theconduit15 is a flexible tubular member tending to facilitate its placement within the surgical workspace W with an aim not to encumber access into the retracted chest cavity. Alternatively,conduit15 may also be a malleable tubular member which the surgeon may deform into a desired less obstructive shape.
• The proximal end ofconduit15 is configured with apneumatic fitting11 which may be connected to a negative pressure supply line in the operating room or to a negative pressure manifold along with several other pneumatic fittings when a plurality ofpericardium retraction devices105 are deployed. Thesuction port39 is attached toconduit15 through an attachment fitting399, in either a demountable or permanent assembly as also described by similarity in the second embodiment. Negative pressure is supplied to thesuction port39 through an orifice feature in attachment fitting399 which communicates withconduit passage10 withinconduit15.
• A wire-like filament393 is attached to the attachment fitting399 and serves as a device manipulating means allowing the surgeon to apply the desired tensile retraction load to the pericardium tissue by a pulling action on said wire-like filament. The desired pericardium retraction load to position and orient the beating heart is maintained during the surgical intervention by securing the free proximal end offilament393 tosternum retractor2, through a variety of anchoring mechanisms and methods. For instance, the free end offilament393 may be inserted and partially threaded through an opening in afilament clamp395.Filament clamp395 is comprised of two cooperating jaws which exert a clamping load on the portion offilament393 clamped therebetween. An adjustment means394 is also provided withinfilament clamp395, which when activated, serves to temporarily relieve the clamping action of two said jaws thereby allowing the repositioning offilament clamp395 along the length offilament393. The adjustment means394 may be activated by a variety of methods, such as for instance through the application of a manual compression force on the adjustment means.Filament393 is inserted in a slit-like channel72 or82. With the desired pulling action applied to thefilament393 to achieve pericardium retraction, thefilament clamp395 is repositioned along the length offilament393 and brought into contact withspreader arm3 or4 ofsternum retractor2. By virtue of the imposed retraction load on pericardium tissue,clamp395 is wedged againstspreader arm3 or4 whenfilament wire393 is inserted in slit-like channel72 or82. The clamping action of the jaws onfilament393 secures the resulting filament length between attachment fitting399 andfilament clamp395 thereby maintaining the pericardium and resulting filament length in tension during the surgical procedure.
• A variety of other methods may be used to secure the desired length offilament393 relative to a portion ofsternum retractor2 in order to maintain the desired pericardium retraction load. For instance, the anchoring mechanisms described in copending Canadian patent application Serial No. 2,242,295 filed on Aug. 10, 1998 in the names of Paolitto et al. and entitled “Surgical Instruments for Tissue Retraction”, for which a corresponding PCT application has been filed on Aug. 10, 1999 in the names of Paolitto et al. and entitled “Surgical Suture and Associated Anchoring Mechanism”, the contents of which are incorporated herein by reference, may be used as they relate to the securing of a tensile loaded wire-like filament to a surgical retractor. These existing applications have been assigned to CORONEO Inc., the assignee of the present application.
• Alternatively, a variant to the present fifth embodiment may consist of having oneconduit15 supplying negative pressure suction to more than onesuction port39 disposed at its distal end through a manifold type attachment fitting, as previously described.
• FIG. 14 illustrates a sixth embodiment according to the present invention. In this embodiment, thedeformable suction port39 is replaced by an alternate mechanical tissue-engaging member such as atissue clamp396. Thepericardium retraction device106 is comprised of atissue clamp396, a device manipulating means in the nature of a wire-like filament393, and an anchoring mechanism in the nature of afilament clamp395.
• Thetissue clamp396 is comprised of at least two clamping members which the surgeon or assistant manipulates in a manner to clamp therebetween a portion of the pericardium tissue. Examples include a snap-tight clamp or spring-loaded clamp. Thetissue clamp396 is engaged with pericardium tissue without having to pierce through said pericardium tissue, therefore tending to reduce the likelihood of inducing injury to underlying body tissue behind unraveled pericardium tissue.
• The imposed clamping loads on the portion of pericardium tissue engaged withintissue clamp396 is sufficient to overcome the retraction forces experienced during “verticalization” of the beating heart. Thefilament clamp395 and adjustment means394 are the same as those described in the fifth embodiment and may also be replaced by a variety of other anchoring mechanisms referred to above.
• FIG. 15 illustrates a seventh embodiment according to the present invention. This embodiment incorporates a negative pressure conduit means into the positioning and articulation mechanism, with an aim to improving the ergonomics of the surgical workspace W. Thepericardium retraction device102 is comprised of a tissue-engaging member30 (which is the same as in the first embodiment), a device manipulating means such asshaft member131, and a conduit means such aconduit passage10. The positioning andarticulation mechanism120 is similar to the positioning andarticulation mechanism20 of the previous embodiments except for the modifications introduced to incorporate a conduit means thereof. Apneumatic fitting11 is provided on the proximal end offirst positioning rod25. Aninternal conduit passage250 withinrod25 spans the entire length of the said rod, from the fitting11 inlet to thespherical rod end251. A flexibletubular coupling253 plugs into thespherical rod end251 ofrod25 atjunction interface252. The flexibletubular coupling253 extends through a portion ofshaft member131 to communicate withconduit passage10 within saidshaft member131. Thepericardium retraction device102 is engaged within the clampingmembers262 of thesecond articulation member26 and secured between said clampingmembers262 by tensioningknob261. The flexibletubular coupling253 allows for a substantially similar deployment and substantially similar motion degrees of freedom ofmechanism120 relative to the positioning andarticulation mechanism20 of the previous embodiments.
• In the embodiments of the present invention requiring a negative pressure supply, the source for this said negative pressure may be either a suction line generally available in operating rooms, or alternatively an auxiliary vacuum pump to provide an independent negative pressure supply or a pressure boost to the suction available in the operating room.
• In the embodiments of the present invention described herein, it is intended to produce the bulk of the surgical apparatus from reusable components, whose assembly may be at least partially dismantled, if necessary, for ease of sterilization. All components are manufactured in either surgical grade stainless steel, titanium, aluminum or any other reusable sterilizable material suitable for surgical use. Components produced from polymeric materials are either reusable through specific sterilization procedures tailored to these component materials, or must be replaced after every use or after a predetermined number of uses if the polymeric material properties are not suitable for sterilization or degrade after repeated sterilization cycles. However, any number of the said reusable components may also be produced from disposable surgical grade plastics, if the case for disposable components is warranted and if the engineering and functional intent is maintained when the said component is produced from plastic.
• Some of the features and principles of the embodiments of the present invention may advantageously be applied, if desired, to other surgical apparatus used for engaging body tissue through a negative pressure suction port. The above description of the embodiments of the present invention should not be interpreted in any limiting manner since variations and refinements are possible without departing from the spirit of the invention.

Claims (2)

1. A surgical method for performing a surgical intervention on a target anatomic structure of a patient body, said patient body also including non-target anatomic structures and defining a thoracic cavity, said thoracic cavity including a patient's heart, said heart being substantially contained within a pericardium tissue and anatomically attached to at least a portion thereof, said thoracic cavity also defining a thoracic peripheral wall, said thoracic peripheral wall including a rib cage, said target anatomic structure being located within said thoracic cavity, said surgical intervention involving the use of a pericardium retraction device and surgical platform, said surgical platform being configured and sized for receiving at least a portion of said pericardium retraction device, said method comprising the steps of:

incising said pericardium tissue to expose at least a portion of said heart;

introducing said pericardium retraction device at least partially into said thoracic cavity of said patient body;

bringing said pericardium retraction device in negative pressure suction contact with at least a portion of said pericardium tissue;

positioning said pericardium retraction device in a retracting configuration wherein said pericardium retraction device provides a tensile load on said contacted pericardium tissue thereby positioning said heart being anatomically attached to said pericardium tissue within said thoracic cavity.

2. A surgical method as recited inclaim 2 further comprising the step of at least temporarily coupling said pericardium retraction device to said surgical platform in said retracting configuration.

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