US20040260236A1

Movatterモバイル変換

Info

Publication number: US20040260236A1
Application number: US10/890,875
Authority: US
Inventors: Frank Manning; Charles Peterson; Howard Graham
Original assignee: Cardiac Pacemakers Inc
Current assignee: Cardiac Pacemakers Inc
Priority date: 2002-01-07
Filing date: 2004-07-14
Publication date: 2004-12-23
Also published as: US7493156B2; US20030130598A1

Abstract

Methods involving guide catheters include providing a guide catheter that has an outer sheath having an open lumen and a pre-shaped distal end, and an inner sheath having an open lumen and a distal end provided with a pre-formed shape. A steering tendon is disposed along the outer sheath, a distal end of which is connected to the outer sheath's distal tip. A steering mechanism is connected to a proximal end of the steering tendon and includes a guide handle. The inner sheath is rotated and longitudinally translated relative to the outer sheath, whereby the distal end of the inner sheath assumes its pre-formed shape when the inner sheath's distal end extends beyond the outer sheath's distal end. A pulling force applied to the steering tendon adjustably changes a shape of the outer sheath's pre-shaped distal end. A payload may be advanced through the inner sheath's open lumen.

Description

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 10/041,911, filed on Jan. 7, 2002, to which priority is claimed under 35 U.S.C. § 120, and which is incorporated herein by reference.[0001]

FIELD OF THE INVENTION

The invention relates generally to methods of guiding catheters, and, more particularly, to methods involving dual-sheath, telescoping guide catheters having a steerable outer sheath and pre-formed inner sheath used to locate and cannulate the coronary sinus of a patient's heart.[0002]

BACKGROUND OF THE INVENTION

Guiding catheters are instruments that allow a physician to locate and cannulate vessels in a patient's heart for preforming various medical procedures, including venography and implanting of cardiac pacing devices. Cannulating heart vessels requires navigating a small diameter, flexible guide through the convoluted vasculature into a heart chamber, and then into a destination heart vessel. Once the destination heart vessel is reached, the catheter acts as a conduit for insertion of payloads into the vessel.[0003]

A commonly accessed destination vessel for cardiac pacing lead insertion is the coronary sinus. A pre-shaped guiding catheter is typically used to blindly locate the coronary sinus ostium. This endeavor, however, is complicated by the fact that the location of the coronary sinus ostium may vary appreciably from one patient to another, especially among patients with diseased hearts. Oftentimes, the clinician is entirely unable to locate the coronary sinus ostium using the guiding catheter, and must resort to finding the ostium by “mapping” (interpreting localized bipolar waveforms) using an electrophysiological (EP) catheter and an ECG monitor. After the ostium is located, the guiding catheter is typically used to inject radiographic contrast media into the coronary sinus to highlight the associated venous system, and then a pacing lead is installed within one of the coronary branches.[0004]

Complicating this scenario is the dynamic structural deformation of the heart chambers that occurs from normal cardiac activity during the procedure. This further increases the difficulty of guiding a catheter to its destination. Presently, a considerable amount of time is often spent by the physician when manipulating such catheters within cardiac structures, such as the right atrium, simply trying to locate an anatomical feature of interest, such as the coronary sinus ostium.[0005]

Guiding catheter systems are typically configured with a profile that is optimized for the intended method of access. In the case of accessing the coronary sinus via the right atrium, a catheter with a distal contour including a relatively sharp bend will point the catheter towards the likely location of the coronary sinus once the right atrium is reached. The contours of pre-shaped guiding catheters are generally fixed, and this is typically achieved in production by constraining the distal end within a shaping fixture while warming them until they assume the intended shape (i.e., by “heat setting” their polymer shaft).[0006]

A fixed shape catheter is adequate in many cases where the pathway is not significantly convoluted and the pathway does not deviate significantly between patients. In situations where structural anomalies or significant variations exist, use of a fixed shape catheter may require that the clinician stock multiple size and shapes of catheters to account for potential variations. Fixed shape catheters may require a time consuming trial and error process of inserting and removing different shapes until the destination vessel is successfully accessed.[0007]

There is a need for an improved guide catheter for accessing heart vessels that can dynamically account for anatomical variations and defects associated with the destination structures. The present invention fulfills these and other needs, and addresses other deficiencies of prior art implementations and techniques.[0008]

SUMMARY OF THE INVENTION

The present invention is directed to methods involving guide catheters, including locating and cannulating vessels of the heart. A method according to one embodiment involves providing a guide catheter that includes an outer sheath having an open lumen and a pre-shaped distal end, and an inner sheath having an open lumen and a distal end provided with a pre-formed shape. The inner sheath is disposed within the open lumen of the outer sheath. The distal end of the inner sheath conforms to a shape of the outer sheath when the inner sheath is retracted within the outer sheath. A steering tendon is disposed along the outer sheath, a distal end of which is connected to a distal tip of the outer sheath. A guide handle is connected to a proximal end of the outer sheath, and a steering mechanism is disposed on the guide handle. The steering mechanism is connected to a proximal end of the steering tendon.[0009]

The method further involves axially rotating and longitudinally translating the inner sheath relative to the outer sheath, whereby the distal end of the inner sheath assumes its pre-formed shape when the distal end of the inner sheath is extended beyond the distal end of the outer sheath. A pulling force provided on the steering tendon adjustably changes a shape of the pre-shaped distal end of the outer sheath.[0010]

The method may further involve advancing a payload through the open lumen of the inner sheath. The payload may include a pacing lead, a guidewire, or a combination of guidewire and pacing lead through the open lumen of the inner sheath. The method may also involve injecting a contrast media for venography into the open lumen of the inner sheath.[0011]

A method according to an embodiment of the present invention may involve proximally retracting the inner sheath to remove the inner sheath from the outer sheath, and advancing a payload through the open lumen of the outer sheath. For example, the inner sheath may be proximally retracted to remove the inner sheath from the outer sheath, and a pacing lead may be advanced through the open lumen of the outer sheath.[0012]

The outer sheath of the guide catheter may incorporate at least one pre-stress line extending from the proximal end to a distal tip of the outer sheath. A method of the present invention may involve splitting the outer sheath while retracting the outer sheath in a proximal direction.[0013]

In other embodiments, energy may be delivered from the distal end of at least one of the inner and outer sheaths sufficient to ablate cardiac tissue. In other embodiments, cardiac tissue may be subject to mapping by use of one or more electrodes provided at the distal end of at least one of the inner and outer sheaths.[0014]

Methods of the present invention may further involve sensing one or more of pressure, acceleration, blood flow, or blood velocity at the distal end of at least one of the inner and outer sheaths. Methods of the present invention may also involve sensing one or both of temperature or oxygen saturation at the distal end of at least one of the inner and outer sheaths. Various embodiments may involve occluding blood flow proximate the distal end of at least one of the inner and outer sheaths.[0015]

In accordance with another embodiment, a method of the present invention involves providing a guide catheter of a type previously described. The method may involve inserting a distal end of the catheter into a patient's right atrium via an access vessel and distally extending the inner sheath from the outer sheath. The distal end of the inner sheath assumes a pre-formed shape upon extending beyond the distal end of the outer sheath. The method may further involve providing a pulling force on the steering tendon to modify an angle of the pre-shaped distal end of the outer sheath, axially rotating the inner sheath relative to the outer sheath, and longitudinally translating the inner sheath relative to the outer sheath to direct the distal end of the inner sheath for finding and cannulating the patient's coronary sinus.[0016]

The method may also involve advancing a payload, such as a pacing lead and/or a guidewire, through the open lumen of the inner sheath to insert the payload into the coronary sinus. Methods may also involve proximally retracting the inner sheath to remove the inner sheath from the outer sheath after cannulating the patient's coronary sinus, and advancing a payload, such as a pacing lead, through the open lumen of the outer sheath. Methods according to this embodiment may further involve processes described above.[0017]

The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.[0018]

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of a catheter embodying features of the present invention and illustrating longitudinal translation of an inner sheath relative to an outer sheath;[0019]

FIG. 2 is an external view of the catheter shown in FIG. 1 illustrating the inner sheath rotating within the outer sheath;[0020]

FIG. 3A is an external view of the catheter shown in FIG. 1 further illustrating a deflection of a pre-shaped distal end of the outer sheath[0021]

FIG. 3B is cross section view of Section[0022]1-1 from FIG. 3A;

FIG. 4 is a cut-away view of a patient's heart, showing a catheter embodying features of the present invention deployed within the heart;[0023]

FIG. 5 is an external view of a catheter illustrating a peel-away outer sheath according to an embodiment of the present invention;[0024]

FIG. 6 is an external view of a catheter containing a pacing lead within the outer sheath according to an embodiment of the present invention;[0025]

FIG. 7 is a view of the distal end of a catheter showing an occlusion balloon attached to the inner sheath according to an embodiment of the present invention; and[0026]

FIG. 8 is view of the distal end of a catheter illustrating electrodes on the distal tip of the inner sheath according to an embodiment of the present invention.[0027]

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail herein. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.[0028]

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

In the following description of the illustrated embodiments, references are made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration, various embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without departing from the scope of the present invention.[0029]

With reference to FIG. 1, a guide catheter is shown embodying features of the present invention. The guide catheter includes an[0030]

inner sheath

1, anouter sheath2, and aguide handle3. The guide handle3 is connected to a proximal end of theouter sheath2. The guide handle3 can include a homeostasis device that provides a seal between the inner and

outer sheaths

1,2. Theouter sheath2 contains anopen lumen2A, and theouter sheath2 is typically elongated and flexible. Theouter sheath2 is also adjustably deflectable at a distal end. Theinner sheath1 is movably disposed within theopen lumen2A of theouter sheath2 such that theinner sheath1 can translate longitudinally and rotate axially within theouter sheath2.

The[0031]

inner sheath

1 is typically more flexible than the outer sheath and includes a pre-formeddistal shape4. The more flexibleinner sheath1 conforms to the shape of theouter sheath2 when a substantial portion of the inner sheath's distal end is contained within theouter sheath2. When theinner sheath1 is sufficiently extended, the distal end of theinner sheath1 assumes its pre-formeddistal shape4, as indicated by phantom lines in FIG. 1.

The[0032]

inner sheath

1 can be formed of a polymeric tube. Pebax is a polymer typically used in this application, although other materials such as nylon and PVC may be employed. Constructing theinner sheath1 from a multi-layered tube having a metallic braid may be desirable in some applications where greater stiffness is required. The pre-formeddistal shape4 can be thermoset during manufacture of theinner sheath1.

The[0033]

inner sheath

1 has anopen lumen1A that can receive a payload. An inner lubricous lining made of a material such as PTFE can be provided within theopen lumen1A. The lubricious liner helps to ease advancement of payloads through theopen lumen1A. Aninner sheath1 used in coronary sinus cannulation procedures may have an inner lumen diameter of about 0.030 inches to about 0.100 inches, depending on the size of payloads and/or guide members that are intended to pass through or otherwise be disposed within theopen lumen1A.

The ability of the[0034]

inner sheath

1 to assume a pre-formeddistal shape4 upon inner sheath extension is advantageous for accessing vessels within a patient's heart. For example, when accessing the patient's coronary sinus, a commonly traversed pathway is through a percutaneous access vessel such as the left subclavian, then through the superior vena cava and into the right atrium of the heart. This pathway is a relatively large, smooth curve, andouter sheath2 can be shaped to accommodate the pathway. Theinner sheath1 can be retracted within theouter sheath2 while the guide catheter is being advanced through the pathway, allowing the guide catheter to substantially assume the shape of theouter sheath2.

Once the distal end of the catheter has entered the right atrium, a relatively sharp transition is desirable to access the coronary sinus ostium. The[0035]

inner sheath

1 can now be extended to provide such a transition. Extension of theinner sheath1 past the distal tip of theouter sheath2 allows the distal end of theinner sheath1 to assume its pre-formeddistal shape4. The pre-formeddistal shape4 can have dimensions that are optimized for locating the coronary sinus ostium, in this example. Axial rotation and longitudinal extension of theinner sheath1 within theouter sheath2 beneficially allows the distal end of theinner sheath1 to account for variations within the right atrium while searching for the ostium.

FIG. 2 illustrates the maneuverability provided by the rotatable[0036]

inner sheath

1. Theinner sheath1 is axially rotatable within theouter sheath2. Rotation of theinner sheath1 is typically performed by grasping a proximal section of theinner sheath1 and applying a torque to theinner sheath1 while restraining theouter sheath2. To assist in applying a torque, an attachment may be provided on the proximal end of theinner sheath1, such as awing luer5, shown in FIG. 2. The curved arrows in FIG. 2 show the effect on the distal end of theinner sheath1 caused by rotating thewing luer5. Phantom lines at the distal end of theinner sheath1 illustrate various rotated orientations of theinner sheath1.

To provide further advantages with respect to accessing vessels within a heart chamber, the[0037]

outer sheath

2 is adjustably deflectable. Referring to FIG. 3A, the deflectability of theouter sheath2 is illustrated. The guide catheter includes asteering tendon7 disposed within theouter sheath2. Thesteering tendon7 is attached to the distal end of theouter sheath2, as shown in the detail drawing of FIG. 3A. In one configuration, thesteering tendon7 is attached by bonding or embedding asemicircular plate8 near the outer sheath distal tip. Thesteering tendon7 is fixably attached to thesemicircular plate8. Applying a tensile force on the proximal end of thesteering tendon7 changes a shape of the deflects the distal tip of theouter sheath2.

A steering handle[0038]6 may be attached to the guide handle3 to enable adjustably applying a tensile force to thesteering tendon7. The steering handle6 is typically pivotably mounted on theguide handle3, and may include a friction or lock mechanism to hold the steering handle6 at a fixed position.

To aid in the action of the[0039]

steering tendon

7, theouter sheath2 may include a pre-formeddistal end9. The pre-formeddistal end9 can be optimally shaped for advancement through heart chambers or intended venous pathways. The pre-formeddistal end9 may also determine the deflection point of theouter sheath2 upon application of a tensile force to thesteering tendon7.

As shown in FIG. 3A, the[0040]

outer sheath

2 has an initial shape at the pre-formeddistal end9. The direction of motion of theouter sheath2 as it is deflected by thesteering tendon7 and steering handle6 is indicated by the bold arrows. The deflected positions of thesteering handle6 andouter sheath2 are indicated in phantom lines. Thesteering tendon7 affects a bend angle and a bend radius of the preformeddistal end9, thereby enabling deflection of a distal tip of the guide catheter.

The[0041]

outer sheath

2 may be formed of a polymeric tube similar to theinner sheath1. Theouter sheath2 is typically stiffer than theinner sheath1, and may benefit from a multilayer construction that includes a metallic braid or coil. An inner lubricous lining made of PTFE or equivalent material can be provided within theouter sheath lumen2A to reduce friction between the inner and

outer sheaths

1,2. Thesteering tendon7 can be disposed within theouter sheath lumen2A. Thesteering tendon7 can also be disposed along an outer surface of theouter sheath2. Alternatively, theouter sheath2 can contain asecond lumen21 as seen in FIG. 3B. Thesteering tendon7 is deployed within thesecond lumen21. Thesteering tendon7 may be formed of a metallic wire or ribbon, although other tensile members such as a high strength polymer fiber can also be employed with similar results.

A catheter embodying features of the present invention is particularly useful in applications such as implanting pacing and defibrillation leads into heart vessels. This procedure is illustrated FIG. 4. In such an application, the distal end of the catheter is typically introduced through a[0042]

percutaneous access point

10, such as in the left cephalic vein or left subclavian vein. Theinner sheath1 can be retracted within theouter sheath2 while the catheter is advanced through the access vessel into to the heart. As shown this example the catheter advances through the superior vena cava into theright atrium11. In some cases, aguide wire13 may be inserted through the venous pathway before the catheter is introduced, and the catheter then advanced over theguide wire13 into the right atrium.

Once the distal tip of the[0043]

outer sheath

2 has reached the right atrium, theinner sheath1 can be extended. Theinner sheath1 is extended and rotated to locate thecoronary sinus ostium12. Additional assistance in finding theostium12 is provided by deflecting theouter sheath2 via thesteering tendon7. Once theinner sheath1 has located theostium12, theinner sheath1 can be advanced as far as required into the coronary sinus.

If a[0044]

guide wire

13 was introduced prior to inserting the catheter, theguide wire13 can be advanced through theinner sheath1 into the coronary sinus. Theguide wire13 is then distally extended beyond theinner sheath1 into a branch of the coronary sinus. Theguide wire13 can then be used to guide apacing lead14 into the branch vessel. Thepacing lead14 is advanced through theinner sheath1 and seated into the branch of the coronary sinus.

At this point in the procedure, it may be desired to remove at least the[0045]

outer sheath

2. In one configuration, theouter sheath2 can be made with a peel away feature. Turning to FIG. 5, a peel away feature may include one or more longitudinalpre-stress lines15 extending from proximal to distal ends along theouter sheath2. The advantages of a peel-away feature include the ability to proximally remove theouter sheath2 over theinner sheath1 seated without disturbing any proximal attachments on theinner sheath1. Proximal attachments on theinner sheath1 may include awing luer5.

A peel-away feature of the[0046]

outer sheath

2 in a catheter according the present invention can further include the ability of the guide handle3 to separate into at least two sections. As seen in FIG. 5, application of forces to the separation grips16 can split theguide handle3. The guide handle3 is connected to theouter sheath2, so guide handle separation can initiate outer sheath separation as well. Further details of exemplary peel-away features are disclosed in commonly owned U.S. application serial no. 10/036,640, filed Dec. 31, 2001 and entitled “Telescoping Guide Catheter With Peel-Away Outer Sheath” (Atty. Docket No. GUID.037US01), which is hereby incorporated herein by reference.

In some cases, it may be desirable to remove the[0047]

inner sheath

1 prior to introducing thepacing lead14. In such a case, thepacing lead14 is advanced through theouter sheath2. This may be desirable as theouter sheath lumen2A is larger than that of theinner sheath1. In this scenario, theouter sheath2 is distally advanced over theinner sheath1 until theouter sheath2 is seated in the coronary sinus. Theinner sheath1 is then proximally retracted and removed, whereupon pacing lead insertion can proceed through theouter sheath2.

This situation is illustrated in FIG. 6, where the[0048]

pacing lead

14 is shown extending from the distal end of theouter sheath2. Theouter sheath2 illustrated in FIG. 6 also employs a distally mountedocclusion balloon15. Theocclusion balloon15 can be inflated when theouter sheath2 is in a vessel where blockage of blood flow is desired. Blood flow can be temporarily occluded in this way before injecting a contrast media, for example. Theocclusion balloon15 is typically inflated by a fluid injected from a proximal end of theouter sheath2. Methods of mounting and actuating theocclusion balloon15 are well known in the art.

FIG. 7 illustrates an[0049]

occlusion balloon

16 mounted on the distal end of theinner sheath1. Actuation and disposition of theocclusion balloon16 is similar to that described for theocclusion balloon15 mounted on theouter sheath2.

Another useful configuration of a guide catheter according to the present invention includes attaching electrodes to a distal end of the guide catheter. FIG. 7 shows[0050]

electrodes

17 mounted on the distal end of theouter sheath2. Theelectrodes17 are typically flush mounted, and are connected to at least oneconductor18 that is disposed between the distal and proximal ends of theinner sheath1.

FIG. 8 shows[0051]

electrodes

19 mounted on theinner sheath1 in a similar fashion as theelectrodes17 on theouter sheath2. Theelectrodes19 are connected to at least oneconductor20 that is disposed within theinner sheath1. It is understood the electrodes may be disposed on both the inner and

outer sheaths

1,2 in certain configurations.

The[0052]

electrodes

17,19 can be used for electrophysiological (EP) purposes, such as EP mapping structures within the heart. EP electrodes are often fabricated from stainless steel, although the

electrodes

17,19 could be made of platinum, silver or other electrode materials known in the art. A guide catheter according to the present invention can also be adapted to use ablation electrodes. Ablation electrodes are typically formed of platinum/iridium, and can be mounted as previously described and illustrated in FIGS. 7 and 8.

Another adaptation of a catheter according to the present invention includes attaching one or more pressure sensing devices to at least the distal end of the inner and/or[0053]

outer sheaths

1,2. A pressure sensor, for example, can detect dynamic characteristics of blood flow, including fluid velocity. Tubular piezoelectric sensors can be configured to sense pressure on theinner sheath1, and can be deployed in a similar manner to theelectrodes19 shown in FIG. 8. As with theelectrodes19, at least oneconductor20 would be coupled to the pressure sensing device and disposed within the inner or

outer sheath

1,2. Other sensors that can be similarly incorporated on the inner and

outer sheaths

1,2 include a temperature sensor, activity sensor (e.g. accelerometer) or oxygen sensor.

It will, of course, be understood that various modifications and additions can be made to the preferred embodiments discussed hereinabove without departing from the scope of the present invention. Accordingly, the scope of the present invention should not be limited by the particular embodiments described above, but should be defined only by the claims set forth below and equivalents thereof.[0054]

Claims

What is claimed is:

1. A method, comprising:

providing a guide catheter, comprising:

an outer sheath comprising an open lumen and a pre-shaped distal end;

an inner sheath comprising an open lumen and a distal end having a pre-formed shape, the inner sheath disposed within the open lumen of the outer sheath, the distal end of the inner sheath conforming to a shape of the outer sheath when the inner sheath is retracted within the outer sheath;

a steering tendon disposed along the outer sheath, a distal end of the steering tendon connected to a distal tip of the outer sheath;

a guide handle connected to a proximal end of the outer sheath; and

a steering mechanism disposed on the guide handle, the steering mechanism connected to a proximal end of the steering tendon;

axially rotating and longitudinally translating the inner sheath relative to the outer sheath, the distal end of the inner sheath assuming the pre-formed shape when the distal end of the inner sheath is extended beyond the distal end of the outer sheath; and

providing a pulling force on the steering tendon to adjustably change a shape of the pre-shaped distal end of the outer sheath.

2. The method ofclaim 1, further comprising advancing a payload through the open lumen of the inner sheath.

3. The method ofclaim 1, further comprising advancing a pacing lead through the open lumen of the inner sheath.

4. The method ofclaim 1, further comprising advancing a guide wire through the open lumen of the inner sheath.

5. The method ofclaim 1, further comprising

proximally retracting the inner sheath to remove the inner sheath from the outer sheath; and

advancing a payload through the open lumen of the outer sheath.

6. The method ofclaim 1, further comprising:

advancing a pacing lead through the open lumen of the outer sheath.

7. The method ofclaim 1, further comprising injecting a contrast media for venography into the open lumen of the inner sheath.

8. The method ofclaim 1, wherein the outer sheath of the guide catheter further comprises at least one pre-stress line extending from the proximal end to a distal tip of the outer sheath, the method further comprising splitting the outer sheath while retracting the outer sheath in a proximal direction.

9. The method ofclaim 1, further comprising delivering energy from the distal end of at least one of the inner and outer sheaths sufficient to ablate cardiac tissue.

10. The method ofclaim 1, further comprising mapping cardiac tissue by use of one or more electrodes provided at the distal end of at least one of the inner and outer sheaths.

11. The method ofclaim 1, further comprising sensing pressure at the distal end of at least one of the inner and outer sheaths.

12. The method ofclaim 1, further comprising sensing temperature at the distal end of at least one of the inner and outer sheaths.

13. The method ofclaim 1, further comprising sensing blood flow or blood velocity at the distal end of at least one of the inner and outer sheaths.

14. The method ofclaim 1, further comprising sensing oxygen saturation at the distal end of at least one of the inner and outer sheaths.

15. The method ofclaim 1, further comprising sensing acceleration at the distal end of at least one of the inner and outer sheaths.

16. The method ofclaim 1, further comprising occluding blood flow proximate the distal end of at least one of the inner and outer sheaths.

17. A method, comprising:

providing a guide catheter, comprising:

an outer sheath comprising an open lumen and a pre-shaped distal end;

a guide handle connected to a proximal end of the outer sheath; and

inserting a distal end of the catheter into a patient's right atrium via an access vessel;

distally extending the inner sheath from the outer sheath, the distal end of the inner sheath assuming the pre-formed shape upon extending beyond the distal end of the outer sheath; and

providing a pulling force on the steering tendon to modify an angle of the pre-shaped distal end of the outer sheath, axially rotating the inner sheath relative to the outer sheath, and longitudinally translating the inner sheath relative to the outer sheath to direct the distal end of the inner sheath for finding and cannulating the patient's coronary sinus.

18. The method ofclaim 17, further comprising advancing a payload through the open lumen of the inner sheath to insert the payload into the coronary sinus.

19. The method ofclaim 17, further comprising advancing a pacing lead through the open lumen of the inner sheath to insert the payload into the coronary sinus.

20. The method ofclaim 17, further comprising advancing a guide wire through the open lumen of the inner sheath to locate the coronary sinus.

21. The method ofclaim 17, further comprising:

proximally retracting the inner sheath to remove the inner sheath from the outer sheath after cannulating the patient's coronary sinus; and

advancing a payload through the open lumen of the outer sheath.

22. The method ofclaim 17, further comprising:

advancing a pacing lead through the open lumen of the outer sheath.

23. The method ofclaim 17, wherein the outer sheath of the guide catheter further comprises at least one pre-stress line extending from the proximal end to a distal tip of the outer sheath, the method further comprising splitting the outer sheath while retracting the outer sheath in a proximal direction.

24. The method ofclaim 17, further comprising delivering energy from the distal end of at least one of the inner and outer sheaths sufficient to ablate cardiac tissue.

25. The method ofclaim 17, further comprising mapping cardiac tissue by use of one or more electrodes provided at the distal end of at least one of the inner and outer sheaths.

26. The method ofclaim 17, further comprising sensing pressure at the distal end of at least one of the inner and outer sheaths.

27. The method ofclaim 17, further comprising sensing temperature at the distal end of at least one of the inner and outer sheaths.

28. The method ofclaim 17, further comprising sensing blood flow or blood velocity at the distal end of at least one of the inner and outer sheaths.

29. The method ofclaim 17, further comprising sensing oxygen saturation at the distal end of at least one of the inner and outer sheaths.

30. The method ofclaim 17, further comprising sensing acceleration at the distal end of at least one of the inner and outer sheaths.

31. The method ofclaim 17, further comprising occluding blood flow proximate the distal end of at least one of the inner and outer sheaths.

32. The method ofclaim 17, further comprising injecting a contrast media for venography into the open lumen of the inner sheath after finding and cannulating the coronary sinus.