1 2
BIPLANAR DEFLECTABLE CATHETER FOR As long as this system is intact, impulses are transmitted
ARRHYTHMOGENIC TISSUE ABLATION normally and cardiac rhythm is maintained. The natural
impulse or current flow in the cardiac conduction system,
I. CROSS-REFERENCE TO RELATED however, may be interrupted or altered by congenital defect,
APPLICATIONS 5 disease or injury which can cause the formation of scar
. . . . , tissue. When a sufficiently severe injury or a congenital
xT ^ iTT} °n°^ ... aPPhcatlon defect is present in the cardiac conductive pathways or in the
No. 08/194,853 filed Feb. 14, 1994 now abandoned, which ventricular myocardium, the electrical impulses are not
itself is a continuation of application Ser. No. 07/989,804, transmitted normally and rhythmic disturbances known as
filed Dec. 11,1992 now U.S. Pat No. 5327,905, which in cardiac arrhythmias can occur. With respect to such
turn is a continuation in part application Ser. No. 07/909, disturbances, the term bradycardia is used to describe an
867, filed Jul. 7,1992, now U.S. Pat No. 5354,297 which abnormal slowing of the cardiac contractions and the term
in turn is a continuation-in-part of application Ser. No. tachycardia is used to describe abnormally rapid heart
07/835,553, filed Feb. 14, 1992, now abandoned. action wj^g either of mese conditions can endanger the life
Reference is made to applications Ser. Nos. 07/840,026, of the patient, tachycardia is more serious, particularly in
now U.S. Pat. No. 5,242,441 and 07/909,869, now U.S. Pat patients having underlying heart disease.
No. 5,263,493 which is a continuation-in-part of application Ventricular tachycardia and other ventricular arrhythmias
Ser. No. 07/840,162, now abandoned of common inventor- have been treated with a number of drugs such as lidocaine,
ship. Each of the cross-referenced applications also are quinidine and procainamide. In cases of excessive sympa
directed to improved catheters. 2Q thetic nervous activity or adrenal secretion, Beta blocking
n. FIELD OF THE INVENTION *f hTM ^ "^fTM ^» ^ th«*Pv has
ineffective in preventing tachyarrhythmias, certain surgical
The present invention is directed generally to an improved procedures have been used to ablate the arrhythmogenic
catheter apparatus for use in the field of cardiac arrhythmia tissue either from the atrium or the ventricles. This proce
ablation. In particular, the invention involves the use of a 25 dure involves extensive surgery in which an incision through
biplanar deflection system which greatly increases the the pericardium and heart muscle is made to locate the
maneuverability of the catheter tip in the lateral plane arrhythmogenic tissue, which is then frozen or surgically
generally perpendicular to that of the disposition of the main removed to be replaced by scar tissue,
catheter tube. This allows the operator to direct the tip of the Because open-heart surgery is a high risk procedure
catheter in multiple directions and maneuver the catheter as 30 which requires a prolonged period of hospitalization and
close as possible to the site of the arrhythmogenic tissue of recuperation, a less traumatic solution is needed. In
interest to accomplish effective ablation. response, catheters of various types have been devised and
used for diagnosing and treating a number of cardiac abnormalities to avoid the trauma of open-heart surgery. For
Normal cardiac pacing, in a healthy heart, is controlled by 35 example, as a method for resolving atherosclerotic plaque
a special structure known as the sinoatrial node (SA node). build up, stenotic lesions are now routinely opened by the
This is the natural pacemaker of the heart and is a special- use of balloon angioplasty. In this procedure, a balloon
ized tissue located within the muscle walls of the right carrying catheter is navigated through the patient's vascular
atrium. The SA node provides impulses which dominate the system to the location of the stenosis. The balloon is inflated
inherent or natural rhythmic contractions of the heart atria 40 by fluid injected through a lumen of the catheter to apply
and the ventricles. This dominance or control involves the pressure to the walls of the clogged vessel, thereby opening
transmission of ionic impulses through cardiac conduction it
pathways in the atria and the ventricles which cause the heart Catheter devices have also been used to locate and ablate to contract and relax in an orderly sequence at a rate dictated cardiac conduction pathways. One such device is shown in by the SA node. This sequence ensures that blood flow to the 45 U.S. Pat No. 4,785,815, in which a catheter tube carries at systemic circulation or the pulmonary system will be maxi- its distal end at least one electrode for sensing membrane mized with each ventricular contraction. The SA node has its potentials within the heart, together with a heating device for own inherent rate which can be modified by signals from the ablating at least a portion of the pathway located by the nervous system In response to excitement, physical activity, sensing device. Another thermal ablation catheter for etc., the sympathetic and parasympathetic nervous systems 50 microtransection or macrotransection of conduction pathreact to modify the rate. ways within the heart, which uses a resistive heating element A depolarization impulse begins with the SA node and at its distal end for highly localized treatment, is illustrated spreads as an electrical wave from its location in the right and described in U.S. Pat No. 4,869,248. These devices are atrium across to the left atrium and down toward the generally effective once the ablating element is properly transition zone between the atrium and the ventricles where 55 positioned at the localized area of interest. A catheter device another node, known as the atrioventricular (A-V) node or tip of the class described has also been developed which junction, is located. This impulse conducts through the A-V employs a single, handle operated deflection wire. Such a node in a slower fashion and continues to a common device is disclosed in U.S. Pat No. 4,960,134. pathway known as the Bundle of His between the right and Electrophysiological catheter ablation procedures often left ventricles, then into multiple paths called right and left 60 have been hampered by the inability of the operator to bundle branches, each bundle branch supplying one ven- maneuver the catheter tip to the precise location of the tricle. These bundle branches then divide into an extensive arrhythmogenic tissue. This is primarily a result of the network of finer paths of conducting tissue which spread limited maneuverability of the catheter tube itself. The from the inner to the outer surfaces of the heart and which catheter tube must have sufficient strength and stiffness to be are referred to as the Purkinje fibers. These fibers feed the 65 guided through the vascular system to the vicinity of the depolarization impulse into all portions of the ventricular tissue of interest. This construction does not allow the myocardium. degree of flexibility at the tip of the catheter needed to
