WO2001036016A2

WO2001036016A2 - Cavo-tricuspid isthmus ablation catheter

Info

Publication number: WO2001036016A2
Application number: PCT/US2000/041913
Authority: WO
Inventors: David Schwartzman
Original assignee: Zynergy Cardiovascular, Inc.
Priority date: 1999-11-05
Filing date: 2000-11-06
Publication date: 2001-05-25
Also published as: WO2001036016A3; WO2001036016A9; AU2751201A

Abstract

A catheter assembly includes a catheter body (20) having a shaft portion (28) and an arm (30) portion, the arm portion having an adjustable defection in plane and out-of-plane relative to the shaft portion. An electrode disposed within the arm portion upon being energized is capable of ablating the entire cavo-tricuspid isthmus region of a heart without repositioning of the catheter body arm portion. An irrigation aperture located within the shaft portion of the catheter body supplies conductive biological fluid which acts as a virtual electrode for the ablation procedure.

Description

CAVO-TRICUSPID ISTHMUS ABLATION CATHETER Background of the Invention

The cavo-tricuspid isthmus (CTI) is an area of the right atrium which has importance for the promulgation of type I (typical or isthmus-dependent) atrial flutter (AFL). a type of arrhythmia. Although AFL is the most common arrhythmia which utilizes the CTI, other atrial arrhythmias may also utilize the CTI. Examples of these are atrial fibrillation (AF) and atypical (type II or non- isthmus dependent) atrial flutter (AAFL).

Previous studies have demonstrated that ablation of the CTI can be performed by creating a myocardial lesion extending from the inferior vena caval orifice to an inferior aspect of the tricuspid annulus. This lesion must be contiguous and transmural throughout its course, so as to prohibit impulses from traversing the CTI. Heretofore, ablation in the CTI has been accomplished by moving a standard ablation electrode catheter along a perceptual line in the CTI, effectively "connecting the points" to form a full length CTI lesion. More recently, some publications have preliminarily reported the use of prototype devices with multiple electrodes which conceptually can result in CTI ablation with a single catheter positioning. However, these catheters have not been designed specifically for the unique

anatomy of the CTI.

There has been a very high rate of success with CTI ablation using standard ablation electrodes. However, in general, procedure and fluoroscopy times are long. Clearly, a technology which decreased procedure and fluoroscopy time would be advantageous and of major benefit.

To explain how the current invention is a novel advance of existing art, the anatomical features of the CTI must be discussed. Figures 1A-B below show two extreme profiles of the CTI typical of different patients.

Referring to Figures 1A-B, catheters which perform ablation are inserted in the femoral vein and enter the heart via the inferior caval orifice 2. The CTI 1 spans between the inferior caval orifice and the tricuspid annulus 3. This entire distance must be ablated to achieve successful CTI ablation. The topography of the CTI is highly variable. It can range from a relatively flat surface (see Figure 1A), or it can be very "pouch-like," extending well below the inferior caval orifice (see Figure IB). In addition, in some patients, a Eustachian ridge 4 adds an additional barrier between the inferior caval access port and the CTI. The resulting requirements for catheter deflection to access the CTI range markedly in individuals; examples of these requirements are demonstrated by the curved arrows in the figures. There is an additional variable: a catheter introduced from the inferior cava can sit anywhere within the cava, ranging from posterior to anterior (see Figure 1A). Variation in catheter position in the inferior cava has major ramifications for catheter design for CTI ablation. For example, if the catheter dwells in the posterior aspect of the inferior cava, the CTI ablation catheter must reach across a long distance in order to simply reach the posterior aspect of the CTI, and then must reach further and in increments to reach the tricuspid annulus aspect of the CTI. If the catheter dwells anteriorly in the CTI, then the requirements would be completely different.

As stated above, the current practice is to use a standard ablation catheter which has a single electrode and a single plane deflection as shown in Figure 2.

The general shape of these catheters is shown in Figure 2. The catheter has a single electrode which can be of variable length. The catheter has no adjustment for its shaft position in the inferior vena cava. The "reach" of the catheter is fixed, so that if the catheter cannot reach far enough into the CTI. then ancillary equipment (e.g. long vascular sheaths) is necessary. The catheter deflection is not designed to conform to the CTI topography. The electrodes are platinum and may contain lumen(s) to irrigate with biological fluids such as saline. Some of these catheters also contain multiple electrodes with the same limitations as to shape. These catheters contain support elements such as shims in the arm section which render the arm relatively firm and unlikely to adhere to the CTI topography.

Summary of the Invention

A catheter assembly for cavo-tricuspid isthmus ablation includes a catheter body having a shaft portion and arm portion. The arm portion of the catheter body has two regions capable of deflection adjustment in plane and out-of-plane as defined by the shaft portion, respectively. At least one electrode is disposed within the arm portion of the catheter body such that upon energizing at least one electrode, the cavo-tπcuspid isthmus region of a heart is ablated without repositioning of the catheter body

A process of ablating cavo-tricuspid isthmus tissue of a heart includes positioning a catheter electrode in a contact position with the cavo-tricuspid isthmus region and thereafter energizing the catheter electrode to ablate the entire cavo-tricuspid isthmus while in the contact position. Brief Description of the Drawings Figure 1A-B is a schematic illustrating the range of anatomical differences m the cavo-tricuspid isthmus of individuals, Figure 2 is a schematic of a standard ablation catheter having a single electrode and a single plane deflection; and

Figure 3 is a schematic of a catheter according to the present invention: (A) spanning the cavo-tricuspid isthmus, (B) alone in an in-plane configuration, (C) in cross-section through the shaft portion, (D) in bottom view through the shaft portion showing irrigation apertures sized an spaced to facilitate uniform irrigation therethrough, and (E) alone m an out-of-plane configuration.

Detailed Description of the Invention

The present invention provides a catheter assembly which has a shape. deflection, and electrode array designed specifically for rapid ablation of the entire CTI with a single catheter positioning. Referring to Figures 3A-E, the catheter assembly is generally shown at 20 and designed to enter the heart via the inferior caval orifice 2 of the inferior vena cava 24, after standard introduction via the right femoral vein. The catheter assembly 20 includes a shaft portion 28 and an arm portion 30 generally formed of a single piece of material. Preferably, the catheter arm portion 30 is constructed of a material which allows the catheter assembly to conform to complex topology in the CTI. The catheter assembly 20 preferably has a maximal diameter of 9 French. The catheter assembly 20 has a preformed deflection in the shaft portion 28 which causes the shaft portion 28 to lie parallel to and in contact with the anterior wall 32 of the inferior vena cava 24.

The arm portion 30 forms an in-plane angle with the shaft portion 28 which is preferable, but can be acute up to 180 degrees and is operator adjustable with a deflection mechanism which is well known in the art and located in a catheter handle (not shown) in order to adjust the angle to firmly contact the anterior wall 32 of the inferior vena cava. The arm portion 30 also forms an out-of-plane angle (see Figure 3E) with the catheter shaft portion 28 which forces it into contact in a relatively medial portion or aspect 30 of the CTI. This medial portion 30 (the posteroseptal space) is like a "gutter" or corner which further constrains the catheter assembly 20 from lateral movement. A secondary bend 34 ensures contact of electrode material with the lip 36 of the tricuspid annulus 3. The arm portion 30 preferably contains only electrode wires - no shims or other support structures, so as to make it very flexible and able to comply with the expected highly variable interindividual isthmus topographical requirements. The cross-section of the catheter shaft portion 28 (Figure 3C) shows it to be oval rather than round, to provide further lateral stability. The "electrode" material (E) is located along the arm portion 30 of the catheter assembly 20 and may be multiple components or a single component. The material is designed to conduct radiofrequency current in the form of flowing saline or similarly conductive biocompatible fluid as a "virtual" electrode.

Referring to Figure 3D, at least one irrigation aperture 38 disposed in fluid communication with the shaft portion 28 of the catheter assembly 20 can be utilized as a conduit for conducting the saline or other similar conductive, biocompatible fluid therethrough forming the "virtual" electrode through which radiofrequency or similar energy from an energy source well known in the art can be applied to the endocardium of the CTI. The location and size of the apertures 38 along the shaft portion 28 can be varied to achieve uniform flow therealong. For example, the apertures 38 can be progressively larger moving from the proximal to the distal ends.

In view of the teaching presented herein, other modifications and variations of the present invention will readily be apparent to those of skill in the art. The discussion and description are illustrative of some embodiments of the present invention, but are not meant to be limitations on the practice thereof. The following claims, including all equivalents thereof, which define the scope of the invention.

It is claimed.

Claims

Claims 1 A catheter assembly for cavo-tπcuspid isthmus ablation, said catheter comprising a catheter body including a shaft portion and an arm portion, said arm portion having a first region lying substantially in the same plane as said shaft portion and a second region lying substantially out of the plane defined by said shaft portion, and at least one electrode disposed on said arm portion for applying ablative energy to a cavo-tπcuspid isthmus region of a heart.

2. A catheter assembly for cavo-tπcuspid isthmus ablation, said catheter comprising' a catheter body having a shaft portion and an arm portion, the arm portion having a first region lying substantially m the same plane as the shaft portion and a second region lying substantially out of the plane defined by the shaft portion; and at least one electrode disposed on the arm portion for applying ablative energy to a cavo-tπcuspid isthmus region of a heart.

3 The catheter assembly of claim 1 wherein the shaft portion and the arm portion of said catheter body are formed of a unitary piece of mateπal

4. The catheter assembly of claim 1 wherein the arm portion of said catheter body is conformed to cavo-tricuspid isthmus region contours.

5. The catheter assembly of claim 1 wherein the arm portion of said catheter body is independent of a shim.

6. The catheter assembly of claim 1 wherein the arm portion of said catheter body has an oval cross-section.

7. The catheter assembly of claim 1 wherein the shaft portion of said catheter body has at least one irrigation aperture therein.

8. The catheter assembly of claim 6 wherein the at least one irrigation aperture is a plurality of irrigation apertures spaced along the shaft portion.

9. The catheter assembly of claim 7 wherein the apertures of said plurality of apertures are spaced and sized to afford uniform flow of a conductive biological fluid therefrom.

10. A process of a bleeding cavo-tricuspid isthmus tissue of a heart

comprising the steps of: positioning a catheter electrode in a contact position with the cavo- tricuspid isthmus of the heart; and energizing the catheter electrode to ablate the entire cavo-tricuspid isthmus while in the contact position.

1 1. The process of claim 9 further comprising the step of: expelling a conductive biocompatible fluid into contact with the cavo- tricuspid isthmus region prior to energizing the catheter electrode.

12. The process of claim 9 wherein positioning said catheter electrode entails adjusting the angle between said catheter electrode and a catheter shaft and adjusting a secondary bend in said catheter electrode distal from the catheter shaft.