Patent Document

CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/101,865, filed Sep. 25, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed toward a defibrillation catheter and more particularly, toward a method and apparatus for facilitating intracardiac atrial defibrillation. 
     Atrial defibrillation is a common arrhythmia that afflicts more than 1.5 million patients in the U.S. alone. It is by far the most prevalent cardiac rhythm disorder associated with hospitalization. Symptoms associated with chronic atrial fibrillation include: awareness of irregularity, palpitations, fatigue, and diminished exercise tolerance. Atrial fibrillation has also been recognized as one of the main contributing factors of embolic strokes. 
     The risks and symptoms associated with atrial fibrillation confirm the necessity for restoration of sinus rhythm. Two commonly employed methods for performing an intracardiac atrial defibrillation procedure are drug therapy and external cardioversion. With regard to drug therapy, studies have shown that there is a risk for proarrhythmic effects, especially in patients with atrial fibrillation and a history of congestive heart failure, which may outweigh the potential benefit of restoring sinus rhythm. 
     There are also risks associated with external cardioversion. Such risks result form the fact that high energy shocks (50 to 360 Joules) are used during the procedure. The high energy shocks can cause heavy muscular contractions with a potential risk of spine or bone fractures, potential pronounced increase in muscle enzymes, induction of ventricular arrhythmias, and overall negative influence on myocardial function. Further, the high energy shocks require the administration of a general anesthetic. 
     In recognition of the foregoing, a method involving internal cardioversion using percutaneous transvenous catheter electrodes has been developed. Internal cardioversion can be performed with energies of less than 12 Joules. However, existing multi-electrode catheters typically do not have the proper arrangement of electrodes to provide the necessary electroshocks to the appropriate locations. 
     SUMMARY OF THE INVENTION 
     The present invention is designed to overcome the deficiencies of the prior art discussed above. It is an object of the present invention to provide a catheter for facilitating atrial defibrillation that uses three electrode arrays on a single catheter. 
     It is a further object of the present invention to provide a method of performing intracardiac atrial defibrillation. 
     In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a catheter for facilitating intracardiac atrial defibrillation that includes an elongated flexible member that has a proximal end and a distal end. Three spaced apart electrode arrays are secured around the periphery of the flexible member in a predetermined pattern so that a first electrode array is adapted to positioned within the superior vena cava, a second electrode array is adapted to be positioned within the right atrium, and a third electrode array is adapted to be positioned within the coronary sinus. Alternatively, the third electrode array may be positioned in the right ventricle rather than the coronary sinus. Electrical leads extend through the flexible member to supply electrical current to the electrode arrays. 
     Other objects, features, and advantages of the invention will be readily apparent from the following detailed description of preferred embodiments thereof taken in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the purpose of illustrating the invention, there is shown in the accompanying drawings forms which are presently preferred, it being understood that the invention is not intended to be limited to the precise arrangements and instrumentalities shown. 
     FIG. 1 is a partial plan view of the first embodiment of the catheter of the present invention inserted into a heart and 
     FIG. 2 is a partial plan view of the second embodiment of the catheter of the present invention inserted into a heart. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail wherein like reference numerals have been used throughout the various figures to designate like elements, there is shown in FIG. 1 a catheter constructed in accordance with the principles of the present invention and designated generally as  10 . 
     In a first embodiment of the present invention, as seen in FIG. 1, the catheter  10  essentially includes an elongated flexible member  12  which may be made of polyurethane. However, the flexible member  12  may be made from a variety of materials such as silicone rubber or plasticized PVC. The flexible member  12  is preferably approximately  110  centimeters long with an outside diameter of approximately 2.5 millimeters. As should be readily apparent to those skilled in the art, only the working portion of the catheter  10  is shown in the drawings. 
     The working portion of the flexible member  12  has a proximal end  14  and a distal end  16 . Carried on the working portion of the flexible member  12  of the catheter  10  are first, second, and third spaced apart electrode arrays, the details of which will be described hereinafter. Electrical wires (not shown) from the electrode arrays pass through the interior of the flexible member  12  to a manifold secured to the remote end of the flexible member  12  for connecting the catheter  10  to appropriate electronic equipment. 
     Located adjacent the proximal end  14  is the first electrode array. The array includes approximately ten electrodes  18   a - 18   j  where each electrode has an approximate length of five millimeters and each electrode is spaced approximately five millimeters away from each adjacent electrode. The second electrode array, located distal to the first array, consists of approximately twelve electrodes  20   a - 20   l.  The length of each of these electrodes is also approximately five millimeters and each electrode is spaced approximately five millimeters away from each adjacent electrode. The third electrode array, located adjacent the distal end  16  consists of approximately seven electrodes  22   a - 22   g.  The length of each of these electrode is approximately five millimeters and each is spaced approximately ten millimeters away from each adjacent electrode. 
     Located within the second array of electrodes  20   a - 20   l  is an atrial pacing/sensing electrode  24 . Also, located at the distal end  16  of the flexible member  12  are bi-polar pacing/sensing stimulation electrodes  26   a  and  26   b.  A steering arrangement known in the art may be associated with the catheter  10  in order to direct the placement of the electrode arrays. 
     In order to perform a defibrillation procedure, the flexible member  12  is introduced into the vascular system from the jugular area in a manner known in the art. The flexible member  12  is then guided into the patient&#39;s heart  28  until it is placed in the desired position. The flexible member  12  is positioned so that the first electrode array  18   a - 18   j  is positioned within the superior vena cava  30 , the second electrode array  20   a - 20   l  is positioned within the right atrium  32 , and the distal end  16  with the third electrode array  22   a - 22   g  is positioned within the coronary sinus  34 . 
     With the flexible member  12  properly in place, electric shocks are applied through the catheter in order to defibrillate the patient&#39;s heart  28 . This is accomplished by connecting the contact pin (not shown) at the proximal end of the proximal lead (not shown) attached to the first and second electrode arrays and the contact pin (not shown) of the distal lead of the third electrode array to an appropriate power source. Thereafter, low energy electrical current is supplied through the electrical leads to the corresponding electrode arrays in order to achieve a normal sinus rhythm in the patient. 
     More specifically, the atrial pacing/sensing electrode  24  and the bi-polar pacing/sensing stimulation electrodes  26   a  and  26   b,  sense the occurrence, if any, of fibrillation. If fibrillation is sensed, the heart  28  is defibrillated or cardioverted by the application of at least one electrical shock between the first and second arrays of electrodes  18   a - 18   j  and  20   a - 20   l,  respectively, which are connected to the proximal electrical lead and the third array of electrodes  22   a - 22   g  which is connected to the distal electrical lead. The two proximal common arrays  18   a - 18   j  and  20   a - 20   l  on the catheter are coupled together as an anode and the single array  22   a - 22   g  on the distal end  16  of the catheter is a cathode. The polarity of the arrays can be reversed to attempt lower defibrillation thresholds in certain patients. Approximately 1-50 Joules of energy are discharged through the sinoatrial node and the atrioventricular node to terminate atrial fibrillation. 
     In a second embodiment of the present invention, as seen in FIG. 2, the catheter  110 , similar to the catheter of the first embodiment, includes an elongated flexible member  112  which may be made of the same types of materials and have the same dimensions as discussed above. Again, only the working portion of the catheter  110  is shown. 
     The working portion of the flexible member  112  has a proximal end  114  and a distal end  116 . Carried on the working portion of the flexible member  112  of the catheter  110  are first, second; and third spaced apart electrode arrays, the details of which will be described hereinafter. Electrical wires (not shown) from the electrode arrays pass through the interior of the flexible member  112  to a manifold secured to the remote end of the flexible member  112  for connecting the catheter  110  to appropriate electronic equipment. 
     Located adjacent the proximal end  114  is the first electrode array. The array includes approximately ten electrodes  118   a - 118   j  where each electrode has an approximate length of five millimeters and each electrode is spaced approximately five millimeters away from each adjacent electrode. The second electrode array, located distal to the first array, consists of approximately twelve electrodes  120   a - 120   l.  The length of each of these electrodes is also approximately five millimeters and each electrode is spaced approximately five millimeters away from each adjacent electrode. The third electrode, located adjacent the distal end  116  consists of approximately seven electrodes  122   a - 122   g.  The length of each of these electrode is approximately five millimeters and each is spaced approximately ten millimeters away from each adjacent electrode. 
     Located within the second array of electrodes  120   a - 120   l  is an atrial pacing/sensing electrode  124 . Also, located at the distal end  116  of the flexible member  112  are bi-polar pacing/sensing stimulation electrodes  126   a  and  126   b.  A steering arrangement known in the art may be associated known with the catheter  110  in order to direct the placement of the electrode arrays. 
     In order to perform a defibrillation procedure, the flexible member  112  is introduced into the vascular system from the jugular area in a manner known in the art. The flexible member  112  is then guided into the patient&#39;s heart  128  until it is placed in the desired position. The flexible member  112  is positioned so that the first electrode array  118   a - 118   j  is positioned within the superior vena cava  130 , the second electrode array  120   a - 120   l  is positioned within the right atrium  132 , and the distal end  116  with the third electrode array  122   a - 122   g  is positioned within the right ventricle  134  instead of the coronary sinus, as in the first embodiment, in an attempt to obtain lower defibrillation thresholds. 
     With the flexible member  112  properly in place, electric shocks are applied through the catheter in order to defibrillate the patient&#39;s heart. This is accomplished by connecting the contact pin (not shown) at the proximal end of the proximal lead (not shown) attached to the first and second electrode arrays  118   a - 118   j  and  120   a - 120   l,  respectively, and the contact pin (not shown) of the distal lead of the third electrode array  122   a - 122   g  to an appropriate power source. Thereafter, low energy electrical current is supplied through the electrical leads to the corresponding electrode arrays in order to achieve a normal sinus rhythm in the patient. 
     More specifically, the atrial pacing/sensing electrode  124  and the bi-polar pacing/sensing stimulation electrodes  126   a  and  126   b,  sense the occurrence, if any, of fibrillation. If fibrillation is sensed, the heart  128  is defibrillated or cardioverted by the application of at least one electrical shock between the first and second arrays of electrodes  118   a - 118   j  and  120   a - 120   l,  respectively, which are connected to the proximal electrical lead and the third array of electrodes  122   a - 122   g  which is connected to the distal electrical lead. The two proximal common arrays  118   a - 118   j  and  120   a - 120   l  on the catheter are coupled together as an anode and the single array  122   a - 122   g  on the distal end  116  of the flexible member  112  is a cathode. The polarity of the arrays can be reversed to attempt lower defibrillation thresholds in certain patients. As in the first embodiment, approximately 1-50 Joules of energy are discharged through the sinoatrial node and the atrioventricular node to terminate atrial fibrillation. 
     It should be noted that in both of the embodiments, a continuous flexible electrode may be substituted for any or all of the electrode arrays. This ensures that the electrode is sufficiently flexible so that the same can be easily bent and straightened, as desired, without causing damage to the same. Such an electrode is preferably formed by a process of ion-beam assisted deposition (IBAD). This technology is described in detail in each of U.S. Pat. Nos. 5,468,562; 5,474,797; and 5,492,763, the disclosures of which are incorporated herein by reference. The use of this technique for forming an electrode catheter is also described in co-pending application Ser. No. 08/751,436, filed on Nov. 20, 1996, entitled “Temporary Atrial Defibrillation Catheter with Improved Electrode Configuration and Method of Fabrication.” The subject matter of this co-pending application, commonly owned, is also incorporated herein by reference. The electrodes may also be applied by sputtering, vacuum deposition, printing, or spraying. 
     An advantage of the present system is that it is easy to use because only one catheter is needed. That is, the three electrode arrays are combined onto one single catheter. It is far easier and faster for physicians to place one catheter, as opposed to two separate devices, in a patient. Also, it is less traumatic and safer for the patient to have one catheter placed within his or her body as opposed to two or more devices. 
     Another advantage of the present system is that it is easier to use than pulmonary artery defibrillation catheters because electrophysiologists are more familiar with superior vena cava, right atrium, and coronary sinus catheter placement which is routinely used in their practice as opposed to pulmonary artery placement which is used more in pressure monitoring in critical care. 
     The present invention may be embodied in other forms without departing from the spirit or essential attributes thereof and accordingly, reference should be made to the claims rather than to the foregoing specification as indicating the scope thereof.

Technology Category: 1