US20040220655A1 - Electrical conduction block implant device - Google Patents

Abstract

The present invention provides an electrical block implant sized and shaped for securement at the perimeter of the pulmonary ostium of the left atrium. By utilizing various expandable ring designs and optional anchoring mechanisms, the present invention causes even, circular scarring around the perimeter of the pulmonary ostium, achieving reliable blocking of aberrant electrical signals responsible for atrial fibrillation.

Description

RELATED APPLICATIONS
• This application claims priority to U.S. Provisional Application Ser. No. 60/451,865 filed Mar. 3, 2003 entitled Implantable Device to Create Ostial Electrical Block in the Pulmonary Veins for Treatment of Atrial Fibrillation and to U.S. Provisional Application Ser. No. 60/451,864 filed Mar. 3, 2003 entitled Implantable Ring to Create Electrical Block in Pulmonary Vein Ostium for Treating Atrial Fibrillation, the entire contents of both being hereby incorporated by reference.[0001]
BACKGROUND OF THE INVENTION
• Pumping of the human heart is caused by precisely timed cycles of compartmental contractions of the heart muscle which lead to an efficient movement of blood into the heart and out to the various bodily organs. These precisely timed cycles are controlled and directed by electrical signals that are conducted through the cardiac tissue and can be referred to as pacing signals.[0002]
• The sinoatrial node (SA node) is the heart's natural pacemaker, located in the upper wall of the right atrium. The SA node spontaneously contracts and generates nerve impulses that travel throughout the heart wall causing both the left and right atriums to sequentially contract according to a normal rhythm for pumping of the heart. These electrical impulses continue to the atrioventricular node (AV node) and down a group of specialized fibers called the His-Purkinje system to the ventricles. This electrical pathway must be exactly followed for proper functioning of the heart.[0003]
• When the normal sequence of electrical impulses changes or is disrupted, the heart rhythm often becomes abnormal. This condition is generally referred to as an arrhythmia and can take the form of such arrhythmias as tachycardias (abnormally fast heart rate), bradycardias (abnormally slow heart rate) and fibrillations (irregular heart beats).[0004]
• Of these abnormal heart rhythms, fibrillations, and particularly atrial fibrillations, are gaining more and more attention by clinicians and health workers. Atrial fibrillation develops when a disturbance in the electrical signals causes the two upper atrial chambers of the heart to quiver instead of pump properly. When this happens, the heart is unable to discharge all of the blood from the heart's chambers thus creating a situation where the blood may begin to pool and even clot inside the atrium. Such clotting can be very serious insofar as the clot can break away from the atrial chamber and block an artery in the brain, and thereby cause a stroke in the individual.[0005]
• A variety of treatments have been developed over the years to treat atrial fibrillation, namely, treatments to either mitigate or eliminate electrical conduction pathways that lead to the arrhythmia. Those treatments include medication, electrical stimulation, surgical procedures and ablation techniques. In this regard, typical pharmacological treatments have been previously disclosed in U.S. Pat. No. 4,673,563 to Berne et al.; U.S. Pat. No. 4,569,801 to Molloy et al.; and also by Hindricks, et al. in “Current Management of Arrhythmias” (1991), the contents of which are herein incorporated by reference.[0006]
• Surgical procedures, such as the “maze procedure”, have also been proposed as alternative treatment methods. The “maze” procedure attempts to relieve atrial arrhythmia by restoring effective atrial systole and sinus node control through a series of incisions.[0007]
• The Maze procedure is an open heart surgical procedure in which incisions are made in both the left and right atrial walls which surround the pulmonary vein ostia and which leave a “maze-like” pathway between the sinoatrial node and the atrioventricular node. The incisions are sewn back together but result in a scar line which acts as a barrier to electrical conduction.[0008]
• Although the “maze” procedure has its advantages, in practice it can be a complicated and a particularly risky procedure to perform since the surgeon is making numerous physical incisions in the heart tissue. Due in part to the risky nature of the Maze procedure, alternative, catheter-based treatments have been advanced. Many of these catheter devices create the desired electrical block by way of ablation devices designed to burn lesions into the target tissue. Examples of these devices can be seen in U.S. patents: U.S. Pat. No. 6,254,599 to Lesh; U.S. Pat. No. 5,617,854 to Munsif; U.S. Pat. No. 4,898,591 to Jang et al.; U.S. Pat. No. 5,487,385 to Avitall; and U.S. Pat. No. 5,582,609 to Swanson, all incorporated herein by reference.[0009]
• Although ablation catheter procedures remain less invasive than previous surgical methods like the “maze” procedure, they nevertheless retain a significant element of risk. For example, ablation procedures often utilize high power RF energy or ultrasonic energy, which may adequately create electrical block, but their inherent destructive nature allows for the possibility of unintended damage to the target tissue or nearby areas.[0010]
• Further, it is often difficult to achieve certainty as to whether the appropriate amount of ablation has been performed uniformly around the perimeter of the target site or if the desired site is even being ablated.[0011]
• Ablation procedures have also seen an occurrence of stenosis in the pulmonary veins as a response to the ablation. This is a serious complication and as a result, many doctors try to limit their treatment to the ostium of the pulmonary veins to minimize the risk of creating a stenosis in the pulmonary veins.[0012]
• Finally, various implant devices have also been proposed. Examples of such proposed devices are disclosed in co-pending U.S. application Ser. No. 10/192,402 filed Jul. 8, 2002 entitled Anti-Arrhythmia Devices and Methods of Use, the entire contents of which is hereby incorporated by reference.[0013]
• The solutions in the prior art, however, are not believed to be entirely effective in many cases, and indeed may result in actually inducing long term arrhythmias and inefficacy.[0014]
• As a result, what is needed are minimally invasive techniques for creating electrical block in the pulmonary veins which reduce the complication risk of previously known procedures, while increasing effectiveness and speed of the procedure to create electrical block.[0015]
OBJECTS AND SUMMARY OF THE INVENTION
• It is an object of the present invention to provide a minimally invasive device and technique for deploying such a device that safely and effectively blocks aberrant electrical signals at or near the ostium of the pulmonary veins.[0016]
• It is a further object of the present invention to provide a minimally invasive electrical block device that is easy to deploy and has a low risk of complication.[0017]
• It is yet a further object of the present invention to provide an electrical block device that consistently creates a circumferential scar line around the pulmonary ostium to completely block aberrant electrical signals causing atrial fibrillation.[0018]
• The present invention achieves these objects by providing an electrical block implant sized and shaped for securement at the perimeter of the pulmonary ostium of the left atrium.[0019]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1A-1C illustrate three example variations of pulmonary ostia;[0020]
• FIG. 2 illustrates a flattened sectional view of an expandable ring according to the present invention;[0021]
• FIG. 3 illustrates a side view of an electrical block device according to the present invention;[0022]
• FIG. 4 illustrates the electrical block device of FIG. 3 at a pulmonary vein bifurcation;[0023]
• FIG. 5 illustrates the electrical block device of FIG. 3 in an expanded position;[0024]
• FIG. 6 illustrates the electrical block device of FIG. 3 in a fully deployed position;[0025]
• FIG. 7 illustrates the electrical block device of FIG. 3 in a fully deployed position;[0026]
• FIG. 8 illustrates a side view of an electrical block device according to the present invention;[0027]
• FIG. 9 illustrates a side view of an electrical block device according to the present invention;[0028]
• FIG. 10 illustrates a side view of an electrical block device according to the present invention;[0029]
• FIG. 11 illustrates a side view of an electrical block device according to the present invention;[0030]
• FIG. 11A illustrates a side view of an electrical block device according to the present invention;[0031]
• FIG. 12 illustrates a side view of an electrical block device according to the present invention;[0032]
• FIG. 13 illustrates a side view of an electrical block device according to the present invention;[0033]
• FIG. 14 illustrates a side view of an expandable ring according to the present invention;[0034]
• FIG. 15 illustrates a partial close up side view of an expandable ring according to the present invention;[0035]
• FIG. 16 illustrates a flattened sectional view of the expandable ring of FIG. 14;[0036]
• FIGS. 17A and 17B illustrate cross-sectional views of a conduction block device of the present invention in its implanted state;[0037]
• FIG. 18 illustrates another embodiment of the expandable ring design according to the present invention;[0038]
• FIG. 19 illustrates another embodiment of the expandable ring design according to the present invention;[0039]
• FIG. 20 illustrates a side view of an electrical block device according to the present invention;[0040]
• FIG. 21 illustrates a flattened sectional view of a primary expandable ring of FIG. 20;[0041]
• FIG. 22 illustrates a top view of a secondary pressure ring according to the present invention;[0042]
• FIG. 23 illustrates a top view of a secondary pressure ring according to the present invention[0043]
• FIG. 24 illustrates a side view of an expandable ring according to the present invention;[0044]
• FIG. 24A illustrates a flattened sectional view of the expandable ring of FIG. 24;[0045]
• FIG. 25 illustrates a side sectional view of an expandable ring according to the present invention;[0046]
• FIG. 26 illustrates a side sectional view of an expandable ring according to the present invention;[0047]
• FIG. 27 illustrates a flattened sectional view of the expandable ring of FIG. 26;[0048]
• FIGS. 28A-28C illustrate a preferred embodiment of a delivery system in accordance with the present invention;[0049]
• FIGS. 29A-29C illustrate another preferred embodiment of a delivery system in accordance with the present invention;[0050]
• FIG. 30 illustrates another preferred embodiment of a delivery system in accordance with the present invention;[0051]
• FIG. 31 illustrates another preferred embodiment of a delivery system in accordance with the present invention;[0052]
• FIG. 32 illustrates another preferred embodiment of a delivery system in accordance with the present invention;[0053]
• FIG. 33 illustrates another preferred embodiment of a delivery system in accordance with the present invention;[0054]
• FIG. 34 illustrates a side view of an expandable ring according to the present invention;[0055]
• FIG. 35 illustrates a side view of an expandable ring according to the present invention;[0056]
• FIG. 36 illustrates a side view of a deployment apparatus according to the present invention;[0057]
• FIG. 37 illustrates a side perspective view of an electrical block device according to the present invention;[0058]
• FIG. 38 illustrates a side view of the electrical block device of FIG. 35;[0059]
• FIG. 39 illustrates a magnified perspective view of the expandable ring of FIG. 35;[0060]
• FIG. 40 illustrates a side view of the electrical block device of FIG. 35 in a loaded state;[0061]
• FIG. 41 illustrates a side perspective view of the electrical block device of FIG. 35;[0062]
• FIG. 42 illustrates a top view of the expandable ring of FIG. 35 in an expanded state;[0063]
• FIG. 43 illustrates a top view of the expandable ring of FIG. 42 in a cinched state;[0064]
• FIG. 44 illustrates a side perspective view of the electrical block device of FIG. 35; and,[0065]
• FIG. 45 illustrates a top view of the electrical block device of FIG. 35.[0066]
DETAILED DESCRIPTION OF THE INVENTION
• The ostium of the pulmonary veins has a highly variable geometry from one patient to another and this presents difficulty in reliably treating atrial arrhythmias using previous methods. That is, the variable geometry has in the past made it difficult to reliably create a continuous line of electrical block around the perimeter of the ostium in each and every patient.[0067]
• In illustration of this point, FIGS. 1A-1C present three ostium geometries that can occur in the general human population. These Figures show a[0068]left atrium10 of a human heart wherein two adjacentpulmonary veins11 may originate directly from two ostia in the left atrium (FIG. 1B) or may originate from one ostia in the left atrium followed by abifurcation13 downstream of the left atrium. Moreover, thebifurcation13 may be located near the left atrium (FIG. 1A) or far from the left atrium (FIG. 1C). Finally, various hybrids of these geometries are also possible as some people can have more or less than the typical two pulmonary veins originating on each of the right and left sides of theleft atrium10.
• In addition to these geometric variations, the ostia may differ in diameter and location of the side branches from patient to patient. For example, typical target site diameters may range anywhere from about 10 to 30 mm. This provides a considerable challenge for any consistently performed electrical block procedure for the treatment of an atrial arrhythmia.[0069]
• To address this problem, the present invention provides an electrical block device that is implantable and anchorable within the pulmonary veins and/or left atrium of many different geometries. That is, the present invention presents a device and method that is adaptable for use in conducting substantially uniform treatment of a wide segment of the human population.[0070]
• And generally speaking, the present invention performs this function in a way that consistently circumferentially blocks aberrant electrical signals through its presence in the ostium of the pulmonary veins. The electrical block device in accordance with the present invention may act through the mere presence in the ostium and/or through controlled scarring caused by the device.[0071]
• The controlled scarring can be created by a number of possible mechanisms. One possible mechanism is to have the device press against the tissue with enough force to cause pressure necrosis. As the tissue necroses, the device slowly migrates through the wall and scar tissue forms behind the device as it slowly migrates through the tissue wall. With this mechanism, it is possible that the device can ultimately migrate through the entire tissue wall leaving a line of scar through the entire wall thickness.[0072]
• In another possible mechanism, the device can press against the tissue causing tension in the tissue wall. This tension in the tissue can cause fibrosis in the wall without having the device actually pass through the wall as was described for the pressure necrosis mechanism above.[0073]
• Another possible mechanism is to have the presence of the device cause necrosis in the tissue as a result of a reaction to the material of the device or a material attached to the device. It is also possible to use combinations of these mechanisms.[0074]
• The controlled scarring is believed to disrupt the cellular structure of cardiac tissue that is present in or on the pulmonary vein wall or the atrial wall outside the ostia and thereby prevent such cardiac tissue from propagating aberrant electrical signals that cause the atrial arrhythmias. While this invention describes use for electrical isolation of pulmonary veins, these same devices and methods can also be applied to other sites such as the superior vena cava or the coronary sinus.[0075]
• Electrical Block Device with Anchoring Clip[0076]
• A first preferred embodiment of the present invention is depicted in FIGS. 2-7 and comprises an[0077]electrical block device100 that has three main functional components: anexpandable ring102, and ananchoring clip106 and aclip loop104 that connects thering102 with theclip106.
• With reference to FIGS. 6 and 7, it can be seen that in the fully deployed condition of the[0078]device100 in anostium118 of a bifurcated pulmonary vein of the heart, theexpandable ring102 expands against the ostial tissue and theanchoring clip106 abuts against thebifurcation116 of thepulmonary veins114. It can also be seen that theanchoring clip106 is connected to theexpandable ring102 by theclip loop104 that arcs over the diameter of theexpandable ring102.
• The[0079]expandable ring102 expands from its undeployed configuration by as much as 10 times or more beyond its size in a compressed state so as to press around the perimeter of the ostium. This expansile force assists in securing theexpandable ring102 in proper position.
• In addition to its function of spatially positioning the[0080]device100 in the ostial space, theexpandable ring102 also serves as the primary mechanism of creating the desired electrical conduction block. Theexpandable ring102 can cause this electrical block either by inducing controlled scarring of the tissue contacted by thering102 or by the mere presence of the ring itself, or by a combination of the two. And as to the use of controlled scarring, any controlled method of scarring may be used, such as chemical coatings on thering102 that cause scarring, physical scarring devices mounted on thering102, or even mere physical expanding pressure from thering102 against the tissue.
• Referring to FIG. 2, the[0081]electrical block device100 is shown in a cut and flattened sheet configuration for illustrative purposes. As is evident, theexpandable ring102 is structured from a continuous and regularly angled wire that forms an overall wave-like or sinusoidal shape. Two ends of theclip loop104 extend from theexpandable ring102 portion of thedevice100 and terminate in the wire structure that forms theanchoring clip106.
• Preferably, the wire that forms the[0082]electrical block device100 is composed of nitinol or a similar elastic metal and is formed by heat setting to a fully expanded shape. Typically, this heat setting can be performed in an oven or salt bath, and yields a ring that is larger in its formed diameter than the target ostium diameter. As a result, thering102 exerts an outward force against the ostial wall when deployed, holding thedevice100 in contact with the tissue.
• The force exerted by the[0083]expandable ring102 can be adjusted to a desired level by varying the thickness or width of thering102. The diameter/expansion ratio of theexpandable ring102 can also be varied to yield a different profile of force applied to the tissue upon expansion of the ring. Generally, increased expansion pressure better secures theexpandable ring102 in place and may further create more prominent scarring at the target area.
• In one preferred embodiment, the ring can be cut from a Nitinol tube having a diameter of about 0.150 inches and a wall thickness of about 0.015 inches. The struts of the ring can be cut about 0.015 inches wide and with a length between turnarounds of about 0.3 inches. For a target ostia having an internal diameter of 16 mm, this ring could be cut with six cells (i.e., it could have six turnarounds on both the top and the bottom). For this 16 mm target site, the ring could be formed to a diameter of about 20 mm. It should be noted that these dimensions are merely exemplary and that these dimensions can vary.[0084]
• As discussed above, the[0085]clip loop104 arcs over the diameter of theexpandable ring102 when the device is deployed. As a result, as shown in FIGS. 6 and 7, theclip loop104 serves to position theanchoring clip106 at an appropriate distance from theexpandable ring102, and urge theanchoring clip106 against thebifurcation116 between the branches of the pulmonary vein. The curved design ofclip loop104 provides for some flexibility and “springiness” between the anchoringclip106 and theexpandable ring102.
• Referring to FIGS. 2 and 5, the[0086]anchoring clip106 of the present preferred embodiment provides two closely spacedloops103, having asingle barb105 within each of theloops103. When a small portion of tissue of thebifurcation116 moves between the twoloops103, thebarbs105 penetrate into the tissue and thereby retain the tissue between the twoloops103. Any type of clip or anchoring design may be used in place of thepresent anchoring clip106 design, so long as the anchoring device can provide securing force from theexpandable ring102 to the tissue.
• With regard to delivery of the[0087]electrical block device100 to the target site, theelectrical block device100 is first compressed into an undeployed state and is placed within adeployment sheath108, as seen in FIG. 3. Within thedeployment sheath108 is a guidingcatheter112, used for positioning and deploying theelectrical block device100. Theelectrical block device100 sits over the guidingcatheter112 such that theclip loop104 is positioned between twoguide wires110 that extend out from the distal tip of the guidingcatheter112.
• The[0088]guidewires110 are conventional steerable guidewires having diameters typically in the range of 0.014 inches to 0.038 inches and must be steered down the two lumens past the bifurcation. Initially, thesheath108 encapsulates the entireelectrical block device100 against the guidingcatheter112. However, as will be evident from the description below, this positioning configuration allows theelectric block device100 to easily slide off of the guidingcatheter112.
• Referring to FIGS. 3 and 4, the loaded[0089]sheath108 is advanced into the atrium, where the sheath is then partially retracted (or theguide catheter112 is advanced out of the sheath108) so that theclip loop104 protrudes beyond thedeployment sheath108, thereby allowing theguide wires110 to be more easily manipulated and positioned.
• As the[0090]deployment sheath108, guidingcatheter112, andelectrical block device100 are urged towards the pulmonary vein ostia, eachguide wire110 travels down a different pulmonary vein, centering theanchoring clip106 on thebifurcation116 of the pulmonary veins. The closer the guidingcatheter112 comes to thebifurcation116, the more precisely aligned theanchoring clip106 becomes with thebifurcation116 until theanchoring clip106 touches and finally “clips” onto the tissue of thebifurcation116 via thebarbs105 located on theloops103 of theclip106.
• The deployment process continues by simply sliding the[0091]deployment sheath108 back past theexpandable ring102 as is best seen in FIG. 5. Without the containment of thedeployment sheath108, theexpandable ring102 increases in diameter to its formed size, pressing on the target tissue.
• With the[0092]electrical block device100 secured, the guidingcatheter112 anddeployment sheath108 are backed out of the atrium and removed from the body, leaving thedevice100 in its target location as seen in FIGS. 6 and 7.
• Due to the variation in geometry of pulmonary ostia, a pre-operation procedure such as MRI may be helpful to determine the geometry and approximate diameter of the target ostium. With this information, the[0093]electrical block device100 may be better adjusted to suit the patient's target ostium by adjusting aspects such as the expanded diameter of theexpandable ring102, the length of theclip loop104, or the size of anchoringclip106.
• Electrical Block Device With Anchoring Barbs[0094]
• The previously described preferred embodiment positioned and secured the[0095]anchoring clip106 before securing theexpandable ring102. However, the reverse order is also possible according to a preferred embodiment shown in FIG. 8.
• The preferred embodiment as shown FIG. 8 is generally similar to the previous embodiment, with perhaps two main exceptions. In the embodiment as shown in FIG. 8, the first primary difference is the use of positioning barbs[0096]220 with the expandable ring220 and the second primary difference is the use of aclip loop204 that is elastic.
• The barbs[0097]220 are located around the perimeter ofexpandable ring202, providing additional anchoring support when theexpandable ring202 is in the fully expanded position. Theelastic clip loop204 secures on either side of theexpandable ring202, in the same manner as the previous embodiments. However, a portion of each side of theelastic clip loop204 has a multi-angled, wave-likeelastic section205. Thiselastic section205 allows for a degree of variation in the distance between the position of the deployedexpandable ring202 and the bifurcation216.
• In operation, the[0098]electrical block device200 with anchoringbarbs200 is loaded and deployed in a manner similar to the previously described embodiment. Theexpandable ring202 is loaded within adeployment sheath208 and around a guiding catheter, with theelastic clip loop204 to sit betweenguide wires210.
• The[0099]electrical block device200 is positioned near the desired target tissue of the ostia and theguide wires210 are inserted into eachpulmonary vein214. When a desired target location has been achieved, thedeployment sheath208 is withdrawn so as to expose theexpandable ring202. Theexpandable ring202 now being unconstrained, it expands and presses against the target tissue, pushing barbs220 into the perimeter of theostium218.
• Finally, the[0100]anchoring clip206 is secured to the bifurcation216 using guidingcatheter212 to apply pressure on theelastic clip loop204 towards the bifurcation216. Thiselastic section205 enables theelastic clip loop204 to stretch in response to the pressure and thus allows theanchoring clip206 to secure to the bifurcation216. At that point, the guidingcatheter212 anddeployment sheath208 may be removed from the patient.
• In this manner, the electrical block device with anchoring[0101]barbs200 provides the additional anchoring of barbs220 while allowing for an alternative method of deployment. It should be understood that although this preferred embodiment allows theanchoring clip206 to be clipped to the bifurcation216 after expansion of theexpandable ring202, this order is not the only method of deployment. The electrical block device with anchoringbarbs200 may also be deployed in a similar fashion aselectrical block device100 of the first embodiment, as described above, where theanchoring clip206 is clipped to the bifurcation216 first, followed by deployment of theexpandable ring202.
• Electrical Block Device Without Sheath[0102]
• FIG. 9 illustrates yet another preferred embodiment of the present invention. In this embodiment, the overall design of the[0103]electrical block device300 is similar to the previously described embodiments; however, instead of utilizing a deployment sheath, adeployment wire322 is used.
• More specifically, as in previous embodiments, the[0104]electrical block device300 is loaded on a guidingcatheter312 for desired positioning near the perimeter of the ostium. Aclip loop304 is positioned between twoguide wires310 at the tip of guidingcatheter312.
• The main distinction of this design lies in the[0105]expandable ring302, which, unlike previous embodiments, has a series ofholes320 integrated into theexpandable ring302 structure. As seen in FIG. 9, athin wire322 passes through theseholes320 in a circular path and further passes through acatheter wire passage324 within the guidingcatheter312, forming a large loop. The free ends of thethin wire322 are found on the end opposite of theelectrical block device300 of the guidingcatheter312. Such a design allows the tension ofwire322 to control the expansion state of theexpandable ring302.
• The overall operation of this[0106]electrical block device300 is similar to the previously mentioned embodiments above. The user positions the guidingcatheter312 near thebifurcation316 of the pulmonary veins, then attaches theanchoring clip306 using theguide wires310 to assist in proper positioning. Next, the user manipulates thethin wire322 to relieve the compression ofexpandable ring302, allowing thering302 to expand to its full diameter, pressing against the target tissue.
• To remove the[0107]wire322 from theelectrical block device300, a user simply pulls one end of thewire322 until the opposite end is free of both theelectrical block device300 and the guidingcatheter312. At this point, theelectrical block device300 and the guidingcatheter312 are no longer connected, so the user may remove the guiding catheter from the patient, allowing theelectrical block device300 to function as intended.
• This technique of controlling the deployment of the blocking device with a tether wire is shown here for a bifurcated ostium. It is anticipated that this same technique can be applied for other ostial geometries as will be described below.[0108]
• Alternative Electrical Block Device Designs[0109]
• It should be understood that variations on the above described electrical block devices are possible and even desired, depending on a number of factors such as the geometric layout of the ostium of the pulmonary veins. Five variations may be seen in the preferred embodiments of FIGS. 10-13. Consistent with the previous embodiments, these alternative embodiments similarly employ an anchoring structure and an expandable ring structure.[0110]
• Referring to FIG. 10, an[0111]electrical block device400 is comprised of an expandable ring402. Unlike previously described expandable rings, this expandable ring402 has an overall warped structure, lending itself to placement analogous to a saddle over a bifurcation in a pulmonary ostium. In one variation, the expandable ring402 includes anchoringbarbs403 to assist in securing the expandable ring402 in place. In another embodiment (not shown), the anchoringbarbs403 may be absent and the expandable ring402 is secured in place according to the expansion force of the ring402 (based at least in part on the size and thickness of the ring402) against the surrounding tissue.
• In this embodiment, the expandable ring[0112]402 has a wave-like structure similar to previously described embodiments, yet its overall conformation curves upward at the outer sides of the pulmonary veins while the inner portion warps downward toward the left atrium. This overall bent configuration allows theelectrical block device400 to wedge into place at the ostium of the pulmonary veins.
• Referring to FIG. 11, an electrical block device[0113]404 is shown to have anexpandable wire ring408 and anexpandable vein anchor406. Thewire ring408 is an incomplete, non-continuous circle, formed to a diameter larger than the target pulmonary ostium which allows thewire ring408 to self-expand against the target tissue.
• The[0114]expandable vein anchor406 has a circular wave-like (sinusoidal) structure which seats in a branch of the pulmonary vein just past the bifurcation and is connected to theexpandable wire ring408 with at least one wire. Thevein anchor406 has a similar structure to wave-like expandable rings described in previous embodiments. Functionally speaking, thevein anchor406 expands in diameter against the pulmonary vein tissue providing additional anchoring force to secure the electrical block device404 to the target position.
• A variation of the embodiment in FIG. 11 is shown in FIG. 11A. This embodiment of an electrical[0115]conduction block device700 uses a similarexpandable wire ring702 and anexpandable vein anchor704 connected by a connectingwire706. However, theexpandable vein anchor704 in this embodiment is helical as shown in FIG. 11A.
• FIG. 12 illustrates yet another preferred embodiment of an electrical block device[0116]410, this embodiment having anexpandable ring412 and dual ring anchors414. As with previous embodiments, theexpandable ring412 is formed to have a diameter larger than the target ostium diameter, and is designed for seating close to the pulmonary ostium.
• Each of the dual vein anchors[0117]414 seats within a branch of the pulmonary vein, just past the bifurcation, and self expands to a diameter larger than the target diameter of the pulmonary vein and thereby is secured against the pulmonary vein tissue. Wire supports411 connect the dual vein anchors414 to theexpandable ring412 and thereby secure the electrical block device410 in place.
• Turning now to FIG. 13, yet another preferred embodiment of an electrical block device[0118]416 is illustrated. Although this embodiment also is usable with many ostial geometries, it is especially useful with pulmonary ostium having no bifurcation, as seen in FIG. 13. Further, multiple electrical block devices416 can be used for each patient, typically using one electrical block device for each pulmonary vein to provide complete electrical isolation between the left atrium and the pulmonary veins.
• In this embodiment, the electrical block device[0119]416 has an outerexpandable ring420 and an innerexpandable ring418. Both rings420,418 are secured together bywire support422. The innerexpandable ring418 seats within a pulmonary vein, pressing outwardly against the vein tissue while the outerexpandable ring420 seats around the opening of the pulmonary vein. This embodiment allows the two rings to have either common or different functions. They can both be used to generate scarring as described above. They can also be configured such that the innerexpandable ring418 acts primarily as an anchoring/positioning ring and thereby allows outerexpandable ring420 to be held against the tissue around the ostium and to thereby serve as the scar generating ring.
• Both rings[0120]418,420 have an angular wave-like design, allowing for compression in diameter during the pre-deployment phase and self-expansion during the deployment phase. In this fashion, electric block device416 provides an alternative design for varying pulmonary geometries.
• Electrical Block Device Coatings[0121]
• The electrical block devices of the present invention as disclosed herein may be coated with a variety of chemicals or drugs to further enhance functionality. Such coatings may include drugs, chemicals, proteins, or other materials.[0122]
• In one preferred embodiment of the present invention, portions of the electrical block device are coated with stenosis inhibiting drugs such as rapamycin or pacitaxel, as described in U.S. Pat. Nos. 6,273,913 and 6,231,600, the contents of which are hereby incorporated by reference.[0123]
• The portions of the electrical block device which extend into the pulmonary vein may be of the most interest to coat, so as to limit the risk of pulmonary vein stenosis caused by the anchoring component of the implant yet not impacting the scarring response to the expandable ring desired in the ostium.[0124]
• In another preferred embodiment, portions of the electrical block device are coated with a polymer material such as urethane or polyester, in order to promote the desired scarring around the ring while the anchoring components could remain uncoated or have a stenosis inhibiting coating as described above. Such a polymer coating could also be bio-absorbable, allowing for partial integration into the target tissue area.[0125]
• In a further preferred embodiment, the expandable ring has a scar-inducing coating for enhancing the electrical blocking scar formation created by the expandable ring. Such coatings may include polymers, bioabsorbable polymers, platings (e.g., copper), polymers loaded with drugs (e.g., tetracycline), or drugs alone.[0126]
• Expandable Ring Variations[0127]
• Although the expandable electrical conduction block device of the present invention has been described in previous embodiments as primarily relying on a single zigzagging ring, it should be understood that a number of more complex variations are possible. Each variation may have different advantages beneficial to different pulmonary ostia geometries.[0128]
• In a preferred embodiment seen in FIGS. 14-16, an expandable electrical[0129]conduction block device500 is illustrated having a primary ring504 (or primary “cell”) and a secondary ring502 (or secondary “cell”), formed from a single piece of material. As with previously described conduction block devices, this design may be compressed to a smaller size for loading into a deployment sheath or other deployment device so that it expands to a large diameter when free of such deployment devices. FIGS. 14 and 15 shows theconduction block device500 in an expanded state while FIG. 16 shows a sliced and flattened section of thedevice500 in an unexpanded state.
• The electrical[0130]conduction block device500 has aprimary ring504 connected to asecondary ring502 at the angled bend points or strut connection points of each ring. Theprimary ring504 has a wider strut than thesecondary ring502, increasing the stiffness of theprimary ring504, while thesecondary ring502 is shorter in circumference than theprimary ring504. The differing circumferences of each ring allows for an expanded shape seen in FIG. 14, with thesecondary ring502 fully extended to an essentially unbent circle andprimary ring504 extended to an overall wavy/sinusoidal shape. In a preferred embodiment, anchoringbarbs506 are present at the angled bend points ofprimary ring504, providing additional anchoring force to maintain the target position of the electrical block device.
• This two-ringed or two-cell design has a number of advantages, one of which is increased force per area on the target tissue by the[0131]secondary ring502 relative to theprimary ring504. In this regard, the radial force exerted by the device against the wall of the target vessel is driven in large part by the width of the ring material. In other words, a wider ring can expand with more force than a thinner ring. A tissue necrosis mechanism for creating scars is a function of the pressure (force per unit area) exerted by the electrical block device against the target tissue. Since theprimary ring504 is wider than thesecondary ring502 and the two rings are connected together (allowing some of the radial expansion force generated by theprimary ring504 to be applied to the tissue contacted by the secondary ring502), thesecondary ring502 thus causes a greater amount of force per area as between the two. As a result, thesecondary ring502 can be designed to create a desired scar line while theprimary ring504 can be designed to provide the primary anchoring function.
• In this regard, FIGS. 17A and 17B provide a cross-sectional view of how the[0132]secondary ring502 causes the scarring response. FIG. 17A shows the placement of theconduction block device500 immediately after placement of thedevice500 at the target site. As is evident, thebarbs506 have initially engaged the tissue wall but there is not yet any migration of the device into the tissue wall nor any scar line.
• FIG. 17B, on the other hand, shows the configuration of the[0133]conduction block device500 after migration has occurred. As is evident in this embodiment, the greater force per area of thesecondary ring502 has caused thebarbs506 on the top end of thesecondary ring502 to extend into and even break through the tissue wall whereas thebarbs506 at the lower end of theprimary ring504 remain embedded in the tissue wall thickness. As is also evident, this migration has caused the creation of a scar line (indicated by the shaded area503), including ascar line503 that traverses the entire thickness of the tissue wall and encases or encapsulates thebarb506 of thesecondary ring502 that has extended through the tissue wall.
• Another advantage to the dual ring design of the[0134]expandable ring500 is that thesecondary ring502 is stretched into a nearly straight circle thereby allowing thesecondary ring502 to inscribe a substantially straight scar line around the internal circumference of the pulmonary vein. That is, the substantially straight scar line created by thesecondary ring502 avoids forming a scar line that extends axially upstream in the vein (away from the atrium) as would be the case if thesecondary ring502 was configured to have a wave-like shape in the deployed state.
• This is important insofar as the electrical sources that must be isolated from the atrium in treating atrial arrhythmias are suspected to reside in close proximity to the ostium. These sources may be missed or inadequately isolated if the scar line, or a portion of the scar line, is created too far upstream in the vein (away from the atrium). Additionally, as discussed previously, the anatomy around the ostium often includes side branches or curves which make it more difficult to create a full circumferential scar line with a wave-like ring.[0135]
• Finally, the[0136]electrical block device500 that uses two rings (or “cells”) in this manner allows the formation of a discrete, narrow scar line yet has the positional stability of an axially extensive implant. In other words, the use of tworings502,504 in this manner leads to a narrow scar line around the ostium and also provides sufficient axial length so as to better ensure proper deployment and retention at the site. This is important as it is known that implants that have an increased ratio of diameter to axial length are more prone to misdeploy or “tumble” during deployment.
• In a preferred embodiment of the[0137]expandable ring500, theprimary ring504 and thesecondary ring502 are cut from a single tube of memory elastic metal, such as nitinol as shown in FIG. 16. Eachring502,504 of the tubular structure is then stretched over a larger diameter ring and heat set in a furnace at about 540 degrees Celsius. The final formed diameter of each should allow thesecondary ring502 to stretch out to almost a straight circle as shown in FIGS. 14 and 15. The formed diameter of theexpandable ring500 is preferably larger in diameter than the target vessel by 5-100%, and more preferably by about 15% to 40%.
• Electro-polishing components of the[0138]expandable ring500 may be necessary to prevent micro surface cracks from propagating when the device is strained in forming. These cracks can cause the device to fracture and must be eliminated by polishing before applying high strain to the components. Nitinol components of theexpandable ring500 can be electro-polished using percloric acid, nitric acid, or other compounds known to one skilled in the art. It may be desirable to form the device to a higher diameter in which case electro-polishing in stages may be necessary. This results from the fact that some expansion may be needed before being able to polish uniformly and from the fact that polishing may need to precede final expansion.
• FIGS. 18 and 19 show two possible other formed geometries for the[0139]conduction block device500 described with reference to FIG. 16. FIGS. 18 and 19 show the end of thedevice500 with thesecondary ring502 being formed to a larger diameter than the end of theprimary ring504 without thesecondary ring502. As described earlier, the ratio of the diameter of the formed device to the diameter of the target site for the implant is an important driver of the magnitude of the radial force exerted by the device against the tissue of the target site. By forming the device tapered as in FIG. 18 or flared as in FIG. 19, it is possible to produce higher pressures against the tissue under thesecondary ring502 than under most if not all of theprimary ring504. This is independent of the pressure differences resulting from the width differences between the two rings as described previously. The result of this configuration is to have thesecondary ring502 apply enough pressure against the tissue wall to migrate through the wall due to pressure necrosis while most, if not all, of theprimary ring504 applies less pressure against the tissue so that it secures the position of thedevice500 while creating reduced necrosis or fibrosis or, in some cases, perhaps no necrosis or fibrosis.
• Referring to FIGS. 20-22, another embodiment of an[0140]electrical block device511 is shown. As with the embodiment of FIGS. 14-16, thiselectrical block device511 includes aprimary ring508 and asecondary ring514. However, eachring508,514 is formed separately and later assembled to create theelectrical block device511 as discussed below.
• The[0141]primary ring508 has a wave shape in its expanded form as shown in FIG. 20. It is formed from a tube with the cut path around the circumference of the tube shown in FIG. 21. It includes barbed securing spikes510 and anchoringspikes512, as also is seen in FIG. 18. These securingspikes510 are sized to fit withinspike apertures515 that are disposed on thesecondary ring514 which is depicted in FIG. 22. Thus, by inserting the barbed securing spikes510 of theprimary ring508 into thespike apertures515 of thesecondary ring514, the unitaryelectrical block device511 is formed. The assembleddevice511 may then be compressed and expanded as needed for loading and deployment as discussed with previous embodiments. This embodiment allows thesecondary ring514 to project radially out further than theprimary ring508 as shown in FIG. 20. This can aid in focusing the pressure against the tissue to the areas contactd bysecondary ring514.
• Referring to FIG. 23, an alternate preferred embodiment may comprise a[0142]secondary ring516 that functions as described with previous embodiments but that further includes a plurality of points519 arranged around its outer edge. These points provide additional anchoring force, as well as additional scarring capability for thesecondary ring516.
• Referring to[0143]24 and FIG. 24A, another preferred embodiment of anelectrical block device535 is contemplated wherein theprimary ring536 hasstruts537 that are longer than the struts of the primary ring of previous embodiments. Furthermore, thesecondary ring538 is attached to theprimary ring536 withconnection strands533 that extend from the bottom of thesecondary ring538 to the bottom of thestruts537 of the primary ring. This differs from previously described embodiments wherein thesecondary ring538 is connected to the top of the struts of theprimary ring536. As a result, a higher percentage of the main expansion force generated by theprimary ring536 is delivered through thesecondary ring538. It also leads to theprimary ring536 extending axially beyond thesecondary ring538 whereas in previous embodiments, the primary ring is essentially below the secondary ring.
• An advantage to this configuration is as follows. The larger surface area provided by the[0144]primary ring536 leads to a greater dispersion of the expansion pressure (force per unit area) against the tissue by theprimary ring536 and thus mitigates (or even eliminates) the tendency of the struts of theprimary ring536 to penetrate or migrate through the wall of the vessel tissue. At a minimum, this greater surface will slow down the migration rate of the struts as compared to other embodiments and as to the struts of thesecondary ring538. It does not, however, negatively affect the desired expansion pressure (force per unit area) of thesecondary ring538. Hence, a first advantage is that theprimary ring536 may better facilitate the anchoring properties of thedevice535 without degrading the scar inducing properties of thesecondary ring538.
• Another advantage of this configuration relates to how the scar inducing properties of the device are executed by the[0145]device535. If thestruts537 of theprimary ring536 are prevented from migrating into the wall of the tissue, this will better ensure the proper migration of the struts of thesecondary ring538. For example, if the struts of one side of thesecondary ring538 migrate fully through the wall on one side of the vessel before similar migration by the struts on the other side of thesecondary ring538, the circumferential tension (caused by the vessel tissue) necessary for urging the oppositely sided struts to continue their migration will be released unless an independent force is exerted against these oppositely sided struts. This independent force is provided by thestruts537 of theprimary ring536 as follows. Since thestruts537 of theprimary ring536 have not migrated into the tissue (by virtue of the larger surface area of these struts), they retain their expansion force. And because thesestruts537 are independently connected to the struts of thesecondary ring538, then the oppositely sided struts of thesecondary ring538 will continue to encounter the outward expansion forces of theprimary ring536. As a result, uniform migration of the struts of thesecondary ring538 into the surrounding tissue is substantially assured even if the migration of the entire circumference of thesecondary ring538 does not occur simultaneously. In other words, by having theprimary ring536 serve essentially only as an anchoring ring (by virtue of its increased area), uniform outward expansion force is exerted against the struts of thesecondary ring538, regardless of when a portion of the secondary ring may migrate through the vessel tissue.
• Referring to FIG. 25, a variation of the embodiment of FIGS. 24 and 24A may include an[0146]electrical block device520 wherein the struts525 of theprimary ring522 not only extend beyond the struts of thesecondary ring524 but the struts525 are configured to flare outwardly beyond the normal diameter of thedevice520. Configuring the struts525 in this matter allow theelectrical block device520 to better conform to the structure of the ostium and pulmonary vein since typically the ostium expands outwardly as it merges with the atrial wall. This configuration may cause theprimary ring522 to have even better anchoring properties than the embodiment of FIGS. 24 and 24A.
• Referring to FIGS. 26 and 27, another preferred embodiment for causing tissue scarring with an expandable ring is an electrical[0147]conduction block device530 that includes a series ofsmall barbs532 along the length of eachstrut531 of thedevice530. Thesebarbs532 serve to pierce the tissue wall of the vessel at the same time that thedevice530 is being expanded against the vessel wall. Thebarbs532 create small cuts along the pressure path and thereby reduce the pressure (force per unit area) needed for eachstrut531 to migrate through the vessel wall.
• The barbs can be cut in the pattern shown in the flat sheet depiction of the[0148]device530 in FIG. 27, wherein thebarbs532 lay flat, i.e., they lay circumferentially on the device instead of radially outwardly. Thebarbs532 can then be bent into a radially outward position when the device is formed up to its final diameter. Typically this occurs automatically if the ratio of strut thickness to strut width is decreased below about 1.0.
• Furthermore, the embodiment depicted in FIGS. 26 and 27 can be used alone, i.e., as the sole component of the electrical conduction block device or it can be used in a two-ring or “two-cell” design as discussed previously. Referring to FIG. 27, the[0149]device530 can serve as a primary ring as in previously described embodiments wherein a secondary ring can be connected via the apertures that are located at one end of thestruts531 of thedevice530.
• It is desirable to deploy the device in a very controlled and accurate way for all embodiments of the electrical block devices discussed in accordance with the present invention. This includes the capability of deploying the device with a smooth release from the delivery device with no “jumping” of the position of the device in the target vessel. It also includes the capability of repositioning the device or to remove the device if the physician is not pleased with the deployed position of the device.[0150]
• One embodiment of such a delivery system useful particularly for the electrical block devices described previously with respect to FIGS. 13-27 is shown in FIGS. 28A-28C. FIG. 28A shows an[0151]electrical block device500 having a primary504 andsecondary ring502 being deployed out of the end of thedelivery catheter700 into the ostium of a pulmonary vein. This deployment is initiated by drawing back theexternal sheath702 to allow theblock device500 to expand up towards its formed diameter.
• FIG. 28B shows the[0152]electrical block device500 now fully expanded at the site in the ostium of the pulmonary vein ostium. In this drawing it can be seen that theelectrical block device500 is attached to thedelivery catheter700 by an array ofarms539 projecting out from ahub704 on the inner shaft705 of thedelivery catheter700. Thesearms539 are connected to thesecondary ring502 of theelectrical block device500. This array ofarms539 connected to theelectrical block device500 allows the deployment of thedevice500 to be controlled according to the rate theouter sheath702 is pulled back. In the partially deployed state shown in FIG. 28A, thesheath702 constrains the expansion of thearms539 which then act to hold down theelectrical block device500.
• This type of an assembly allows the[0153]device500 to be deployed gradually by controlling the rate that thesheath702 is pulled back along the catheter. This assembly also allows recovery or repositioning of theelectrical block device500 if the physician so wishes by advancing thesheath702 back over thearms539 and theelectrical block device500. FIG. 28C shows thedelivery catheter700 being withdrawn away from the deployedelectrical block device500 after releasing the connection of thearms539 from thedevice500.
• FIGS. 29A-29C show a variation on delivery catheter design described above. In this embodiment the loops formed by the[0154]secondary ring502 of the fully constrainedelectrical block device500 shown in FIG. 16 are used to connect theelectrical block device500 to thedelivery catheter700. These loops are hooked over a ring ofpins540 and are thereby trapped inside thesheath702 of thedelivery catheter700 until thesheath702 is withdrawn back beyond the ring ofpins540. FIG. 29B shows how this allows theprimary ring504 to be deployed while retaining connection to thesecondary ring502 inside the end of thesheath702. If satisfied with the location of theprimary ring504, thesheath702 is then withdrawn fully releasing thesecondary ring502 as shown in FIG. 29C.
• FIG. 30 shows one embodiment in which the[0155]arms539 are hollow tubes having awire708 running from the handle of thecatheter700, down the shaft of the catheter to the array ofarms539, then inside the arm and out the end. Thiswire708 is then wrapped around the strut ofring502 and back into thearm539. Thiswire708 runs back down the arm to a releasable anchor point (not shown) in thecatheter700 shaft or back in the handle (not shown). This connects thearm539 to thestrut502. After theelectrical block device500 has been deployed, thedevice500 can be released by releasing the anchor point on thewire708 and pulling thewire708 out from the catheter handle as is shown in in the far right view of FIG. 30.
• FIG. 31 shows another embodiment of a connecting mechanism in accordance with the invention. In this embodiment, the strut of the[0156]secondary ring502 has anotch710 which provides a nest for a mating notched end of thearm539.Arm539 has awire708 running along it from the catheter handle like that described with respect to FIG. 30. Thiswire708 runs throughholes712 in thearm539 on either side of thestrut502 forming a loop around the strut. The mating notches between thestrut502 and thearm539 act to absorb any axial load that may occur between these two elements during delivery. The connection may be released after deployment of theelectrical block device500 by pulling thewire708 back through theholes712 from the catheter handle as shown in right views of FIG. 31.
• FIG. 32 shows another embodiment of a connecting mechanism in accordance with the present invention. In this embodiment, the strut of the[0157]secondary ring502 has asmall hole714 cut in it. The end of thearm539 has a “U” shapedcradle716 withholes718 cut in each side of thecradle716. The strut is placed in this “U” shapedcradle716 during assembly and asmall pull wire708 as described previously relative to FIGS. 30 and 32 is threaded through theholes718 in the “U” shapedcradle716 and thestrut502. After deployment of theelectrical block device500, this connection can be released by pulling thiswire708 back through theseholes714,718 as shown in the right views of FIG. 32.
• FIG. 33 shows another embodiment of a connecting mechanism in accordance with the present invention. In this embodiment, the strut of the[0158]secondary ring502 has asmall hole720. Thishole720 has a pair ofwires722,724 strung through it. One of thesewires722 has an increaseddiameter726 on its end that will fit through thehole720 when it is the only wire passing through thehole720 but will not fit back through thehole720 if thesecond wire724 has been passed through thehole720 after the increaseddiameter end726 of thefirst wire722 has passed through thehole720. In this way, thesecond wire722 acts as a pin to “lock” thefirst wire724 through thehole720. This process can be reversed as shown in FIG. 33 by withdrawing thesecond wire724 and then withdrawing thefirst wire722 through thehole720.
• As mentioned earlier, the concepts disclosed relative to the previously discussed connecting mechanisms could also be used to attach a delivery device to the[0159]electrical block device500 at locations other than the strut of thesecondary ring502 as shown above. For example, a connecting mechanism such as is shown in FIG. 33 could also be well suited to a hole geometry such as that shown in FIG. 9. In this case the pairs ofwires722,724 would extend radially out from the shaft of thecatheter700 to pass through the holes in the blocking device. These wires could be radially extended or drawn back with a handle connected to these wire pairs. In this way the wires could be used to control the radial expansion of theelectrical block device500 as was described earlier, and be released from theelectrical block device500 when desired by withdrawing the second wire and then the first wire as shown in FIG. 33.
• Variably Expandable Electrical Block Device[0160]
• Yet another preferred embodiment of the present invention illustrates a variably expandable[0161]electrical block device600 anddeployment apparatus616, illustrated in FIGS. 34-45. Generally, thisdevice600 functions in a manner similar to previously described embodiments by causing scarring at the ostium of the pulmonary veins. However, the structure of the variably expandable electrical block device varies from previous designs in that it utilizes a non-continuousexpandable ring602 that allows for compact loading and deployment.
• FIG. 34 shows the non-continuous[0162]expandable ring602 in its flattened, loaded position, while FIG. 35 shows thering602 in its natural coiled position. Theexpandable ring602 has two notable elements: anchoringbarbs604 and ring wire holes606. As the name implies, anchoringbarbs604 provide anchoring support by penetrating the target tissue when theexpandable ring602 is in its natural coiled position. This anchoring support prevents theexpandable ring602 from migration away from the target area while securing portions of theexpandable ring602 to the ostium. Ring wire holes606 are simply holes withinexpandable ring602 that allow acontrol wire618 to pass through.
• Referring to FIG. 36, the[0163]deployment device616 is shown to have adeployment sheath614 and adeployment catheter612. Thedeployment catheter612 is an elongated instrument that slides withindeployment sheath614. Located on the end ofdeployment catheter612 arecontrol arms608, preferably made from nitinol, which serve to deploy theexpandable ring602 at a target location as discussed in greater detail below. Control arm wire holes610 can be seen at the ends of eachcontrol arm608, allowing forcontrol wires618 to pass through each of theholes610 and into a center channel (not shown) of thedeployment catheter612.
• Referring to FIGS. 37 and 38, the present preferred embodiment uses two[0164]control wires618 for manipulating theexpandable ring602. Eachcontrol wire618 takes an overall looped path, extending out of and through the center channel indeployment catheter612, through a controlarm wire hole610, intoring wire hole606, across the diameter of the deployedexpandable ring602, then through the opposite side'sring wire hole606, into an opposite controlarm wire hole610, and finally into the center channel indeployment catheter612. Eachcontrol wire618 consequently crosses the diameter ofexpandable ring602 such that that when both controlwires618 are present, an “X” pattern spans the diameter of theexpandable ring602.
• A user may tighten or loosen these two[0165]control wires618 to manipulate the size of theexpandable ring602. FIGS. 42 and 43 best illustrate this function, as theexpandable ring602 is shown in an expanded and contracted position, respectively.
• The[0166]control wires618 also serve the secondary function of deflecting the anchoringbarbs604 inward to prevent the sharp tips from being exposed until thecontrol wire618 is withdrawn. This deflection can be best seen in FIG. 39.
• Referring to FIG. 40, the variably expanding[0167]electrical block device600 can be seen in a loaded state within the deployment sheath. As with previous embodiments of the present invention, theexpandable ring602 remains within thedeployment sheath614 until the end of the deployment sheath reaches the target location of the pulmonary ostium. Note thatcontrol wires618 are not shown for simplicity of illustration.
• One of the inherent benefits of this design lies in its ability to pass through significantly smaller diameter deployment sheaths for delivery to the desired target site, while expanding to an appropriate diameter, similar to the previously disclosed embodiments of this application.[0168]
• Preferably, the[0169]expandable ring602 could be cut from a flat sheet or tubing made from nitinol, having a thickness of about 0.015 inches and a height of about 0.070 inches. However, a variety of thicknesses and heights may be used so long as loading into a deployment sheath is possible and proper expansion of theexpandable ring602 may be achieved.
• This embodiment of the present invention may be operated by first finding the pulmonary ostium target area with the loaded[0170]deployment apparatus616 as depicted in FIG. 40. Referring to FIGS. 40 and 37, the user pushesdeployment catheter612 within thedeployment sheath614, which, in turn, pushesexpandable ring602 out from thedeployment sheath614. The user continues pushing the deployment catheter untilcontrol arms608 are fully extended from the deployment sheath. During this movement, theexpandable ring602 curls back on itself from its straight shape, forming its relaxed, circular ring shape. This results in the system having the configuration depicted in FIG. 37 in the left atrium.
• Referring to FIGS. 41, 42 and[0171]43, the user is able to control the diameter ofexpandable ring602 for purposes of matching the ring with the target site by simply pulling on thecontrol wires618 to decrease the diameter and/or releasing the wires to increase the diameter. Typically, a user will pull thecontrol wires618 to decrease theexpandable ring602 diameter so as to allow the user to then easily position thering602 at the target position of the ostium.
• In this regard, the[0172]control arms608 are devised so as to have sufficient axial strength so that the user may use them to push theexpandable ring602 forward. The user can track along a guide wire until either theexpandable ring602 wedges into the ostium or until thering602 is aligned with a predetermined axial marker of the desired deployment position.
• Referring to FIGS. 44 and 45, once the proper target position is achieved, the user releases the[0173]control wires618 which then allow theexpandable ring602 to increase in diameter, pushing against the target tissue. When the user is satisfied that theexpandable ring602 is in the proper position, the final step of deployment is performed, namely separating thedeployment apparatus616 from theexpandable ring602. To do this, a user must first removecontrol wires618 from theexpandable ring602 by pulling on one end of eachcontrol wire618. Since only one end of thecontrol wire618 is being pulled, the opposite end will be pulled through its path in theexpandable ring602 and out of the control end of thedeployment catheter612. Eachcontrol wire618 is pulled out of theelectrical block device600 in a similar manner.
• When all of[0174]control wires618 are pulled out, the anchoringbarbs604 are free to bend outwardly from theexpandable ring602 and penetrate the target tissue. Additionally, thedeployment apparatus616 is free to be retracted and removed from the patient, and the procedure may be finished, as best seen in FIGS. 44 and 45.
• Optionally, additional anchoring devices may be used to help secure the electrical block device. Typically, such devices include staples or sutures which are not integral parts of the ring but which are delivered with a separate device that can be tracked into position and fasten the expandable ring to the tissue wall.[0175]
• Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.[0176]

Claims (48)

What is claimed is:

1. A pulmonary vein implant comprising:

an implant framework;

said implant framework being expandable from a delivery state to an expanded state; said expanded state being a state wherein said framework substantially conforms to an internal surface of said pulmonary vein; and,

said implant framework being sized and shaped to have a residual expansion force in said expanded state such that said framework migrates into said internal surface of said pulmonary vein over a period of time.

2. A pulmonary vein implant according toclaim 1, wherein said delivery state is sufficiently small so that said implant framework fits within a delivery device.

3. A pulmonary vein implant according toclaim 1, wherein said residual expansion force of said implant framework in said expanded state is such that said framework migrates substantially completely through said internal surface of said pulmonary vein.

4. A pulmonary vein implant according toclaim 1, wherein said residual expansion force of said implant framework in said expanded state is such that a scar is created in said internal surface of said pulmonary vein.

5. A pulmonary vein implant according toclaim 1, wherein said implant framework is a pulmonary vein stent.

6. A pulmonary vein implant according toclaim 1, wherein said implant framework includes a spatial anchoring section and a conduction block inducing section.

7. A pulmonary vein implant according toclaim 1, wherein said implant framework includes retention surfaces disposed on said implant framework.

8. A pulmonary vein implant according toclaim 7, wherein said retention surfaces are comprised of barbs.

9. A pulmonary vein implant according toclaim 1, wherein said implant framework is an elongated strip when said implant framework is in said delivery state.

10. A method of treating an atrial arrhythmia comprising:

delivering an unexpanded implant to a target site in an ostial region of a pulmonary vein;

expanding said implant to an initial retention state wherein said implant substantially conforms to a wall in said ostial region of said pulmonary vein; and,

allowing said implant to continue to expand over time such that said implant migrates into said wall of said pulmonary vein, said migration causing a tissue response that treats said atrial arrhythmia.

11. A method according toclaim 10, wherein said implant migrates through said wall of said pulmonary vein.

12. A method according toclaim 10, wherein the causing of said tissue response includes causing the formation of scar tissue.

13. A method according toclaim 10, wherein the delivering of an unexpanded implant includes delivering a compressed stent.

14. A method according toclaim 10, wherein the expanding of said implant includes expanding a spatial anchoring section of said implant.

15. A method according toclaim 14, wherein the allowing of said implant to continue to expand includes allowing a conduction block inducing section of said implant to expand into said wall.

16. A method according toclaim 10, wherein the expanding of said implant includes engaging retention surfaces in said wall of said pulmonary vein.

17. A method according toclaim 16, wherein the engaging of said retention surfaces includes engaging barbs on said implant in said wall of said pulmonary vein.

18. A method according toclaim 9, wherein the delivering of an unexpanded implant includes delivering an elongated implantable strip to said target site.

19. A pulmonary vein implant comprising:

an implant framework;

said framework including a spatial anchoring section and a conduction block inducing section; and,

said spatial anchoring section and said conduction block inducing section being substantially separate and distinct from each other along an axial length of said framework.

20. A pulmonary vein implant according toclaim 19, wherein said conduction block inducing section is an expandable ring sized and shaped to reside in an ostial region of said pulmonary vein.

21. A pulmonary vein implant according toclaim 20, wherein said spatial anchoring section comprises an expandable anchoring ring, a substantial portion of which being located downstream of said conduction block inducing section.

22. A pulmonary vein implant according toclaim 21, wherein said expandable anchoring ring is sized and shaped to engage an internal diameter of a pulmonary vein downstream of a bifurcation of said pulmonary vein.

23. A pulmonary vein implant according toclaim 21, wherein said expandable anchoring ring has a greater surface area than a surface area of said conduction block inducing section.

24. A pulmonary vein implant according toclaim 21, wherein said expandable anchoring ring has a substantially greater axial length than said conduction block inducing section.

25. A pulmonary vein implant according toclaim 21, wherein said expandable anchoring ring is fixed to said conduction block inducing section at a proximal end of said expandable anchoring ring.

26. A pulmonary vein implant according toclaim 25, wherein said expandable anchoring ring comprises a plurality of struts that extend proximally beyond said conduction block inducing section along said axial length of said framework.

27. A pulmonary vein implant according toclaim 23, wherein said surface area of said expandable anchoring ring is sufficient to substantially prevent migration of said expandable anchoring ring into a wall of said pulmonary vein.

28. A pulmonary vein implant according toclaim 27, wherein said surface area of said conduction block inducing section is sufficiently small to ensure said conduction block inducing section migrates into said wall of said pulmonary vein.

29. A pulmonary vein implant according toclaim 21, wherein said expandable anchoring ring includes a purality of barbs for penetrating a wall of said pulmonary vein.

30. A pulmonary vein implant according toclaim 21, wherein implant framework is an assemblage of said expandable anchoring ring and said conduction block inducing section.

31. A pulmonary vein implant according toclaim 20, wherein said spatial anchoring section is a clip located distal of said expandable ring and wherein said clip is sized and shaped to engage a bifurcation of said pulmonary vein.

32. A pulmonary vein implant according toclaim 31, wherein said implant framework includes a clip loop spanning across a diameter of said expandable ring and wherein said clip is disposed on said clip arc.

33. A pulmonary vein implant according toclaim 32, wherein said clip loop includes an elastic portion sized and shaped to assist in the positioning of said expandable ring relative to said bifurcation of said pulmonary vein.

34. A pulmonary vein implant comprising:

an elongated strip movable between a relaxed shape substantially conformable with an ostial region in said pulmonary vein and a stressed shape that is substantially linear; and,

said elongated strip having a plurality of retention sections disposed along said elongated strip.

35. A pulmonary vein implant according toclaim 34, wherein said retention sections are comprised of barbs that extend radially when said strip is in said relaxed shape.

36. A pulmonary vein implant according toclaim 34, wherein said elongated strip further includes wire receiving openings, and wherein said wire receiving openings are sized to receive a wire suitable for changing said relaxed shape of said strip.

37. A method of creating an electrical conduction block in a pulmonary vein ostial region comprising:

directing an implant towards said ostial region in said pulmonary vein;

retaining said implant in said pulmonary vein with a first component of said implant;

initiating the formation of scar tissue in said ostial region of said pulmonary vein with a second component of said implant; and,

allowing said implant to remain at said pulmonary vein.

38. A method according toclaim 37, wherein the initiating of said scar formation includes causing said second component to migrate into ostial region tissue.

39. A method according toclaim 37, wherein the retaining of said implant includes expanding said first component to a size that causes an expansion force on the internal walls of said pulmonary vein.

40. A method according toclaim 37, wherein the initiating of the formation of scar tissue includes causing said second component of said implant to migrate into said ostial region at a faster rate than said first component of said implant.

41. A method according toclaim 37, wherein the retaining of said implant includes abutting the implant against a bifurcation of said pulmonary vein.

42. A delivery mechanism for an electrical conduction block device comprising:

a catheter having an inner shaft and a movable sheath; said movable sheath surrounding said inner shaft;

a plurality of expandable arms disposed at a distal end of said inner shaft;

a distal end of each expandable arm having a retention mechanism engageable with one end of said electrical conduction block device; and,

said plurality of expandable arms being selectively expanded or contracted according to movement of said movable sheath.

43. A delivery mechanism according toclaim 42, wherein said retention mechanism comprises a wire that connects said distal end of each expandable arm to a portion of said electrical conduction bock device.

44. A delivery mechanism according toclaim 43, wherein said retention mechanism comprises a strip of material that fits within a groove of a portion of said electrical conduction block device.

45. A delivery mechanism according toclaim 44, wherein said retention mechanism further comprises a wire for securing said strip of material in said groove.

46. A delivery mechanism according toclaim 42, wherein said retention mechanism comprises a cradle that receives a portion of said electrical conduction block device wherein a wire secures said portion of said electrical conduction block device in said cradle.

47. A delivery mechanism according toclaim 42, wherein said retention mechanism includes a plurality of wires that are insertable into a hole of a portion of said electrical conduction block, wherein at least one of said wires has a portion with a larger diameter than the other of said plurality of wires.

48. A delivery mechanism for an expandable electrical conduction block device comprising:

a catheter having an inner shaft and a movable sheath; said movable sheath surrounding said inner shaft;

a ring of pins disposed at a distal end of said inner shaft;

each of said pins being engageable with a mating portion of one end of said electrical conduction block device;

said pins and said mating portion of one end of said electrical conduction block being prevented from disengagement so long as said movable sheath covers said ring of pins; and,

said movable sheath being movable over said ring of pins in one of a forward and reverse direction depending on a deployment decision by a user.

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