WO1999025411A1

WO1999025411A1 - Catheter guiding introducers for use in pediatric hearts

Info

Publication number: WO1999025411A1
Application number: PCT/US1997/021147
Authority: WO
Inventors: Philip J. Saul; James A. Hassett
Original assignee: Daig Corporation
Priority date: 1997-11-18
Filing date: 1997-11-18
Publication date: 1999-05-27

Abstract

A series of precurved guiding introducers for use in the left and right atrium of a pediatric heart to guide ablation catheter to perform ablation or sensing procedures. Also a process for the ablation and mapping of the left and right atria of a pediatric heart is disclosed.

Description

CATHETER GUIDING INTRODUCERS FOR USE IN PEDIATRIC HEARTS

This invention relates to introducers.

More particularly, this invention relates to guiding introducers for use with mapping and ablation catheters in pediatric hearts for mapping and ablation procedures.

BACKGROUND OF THE INVENTION Catheters have been in use for medical procedures for many years. One use of catheters has been to convey an electrical stimulus to a selected location within the human body. Another use is the monitoring of measurements for diagnostic tests within the human body. Thus, catheters may be used by a physician to examine, diagnose and treat while positioned at specific locations within the body which are otherwise inaccessible without more invasive procedures.

Catheters are generally inserted into a major vein or artery which is near the body surface. The catheters are then directed to the specific location for examination, diagnosis or treatment by manipulating the catheter through the artery or vein of the human body.

Catheters have become increasingly useful in remote and difficult to reach locations within the body. However, the utilization of these catheters is frequently limited because of the need for precise placement of the tip of the catheter at a specific location within the body. Control of the movement of catheters to achieve such precise placement is difficult because of the inherent structure of a catheter. The body of a conventional catheter is long and tubular. To provide sufficient control of the movement of the catheter, it is necessary that its structure be somewhat rigid. However, the catheter must not be so rigid as to prevent the bending or curving necessary for movement through the vein, artery or organ to arrive at the specified location. Further, the catheter must not be so rigid as to cause damage to the artery, vein or organ while it is being moved.

While it is important that the catheter not be so rigid as to cause injury, it is also important that there be sufficient rigidity in the catheter to accommodate torque control, i.e., the ability to transmit a twisting force along the length of the catheter. Sufficient torque control enables controlled maneuverability of the catheter by the application of a twisting force at the proximal end of the catheter that is transmitted along the catheter to its distal end. The need for greater torque control often conflicts with the need for reduced rigidity to prevent injury to the body vessel.

Catheters are used increasingly for medical procedures involving the human heart. In these procedures a catheter is typically advanced to the heart through a vein or artery and then is positioned at a specified location associated with the heart. Typically, the catheter is inserted in an artery or vein in the leg, neck, upper chest or arm of the patient and threaded, often with the aid of a guidewire or introducer, through various arteries or veins until the tip of the catheter reaches the desired location that is associated with the heart. The distal end of a catheter used in such a procedure is sometimes preformed into a desired curvature so that by torquing the catheter about its longitudinal axis, the catheter can be manipulated to a desired location within the heart or in the arteries or veins associated with the heart. For example, U.S. Patent No. 4,882,777 discloses a catheter with a complex curvature at its distal end for use in a specific procedure in the right ventricle of a human heart. U.S. Patent No. 5,231,994 discloses a guide catheter for guiding a balloon catheter for the dilation of coronary arteries. U.S. Patent No. 4,117,836 discloses a catheter for the selective coronary angiography of the left coronary artery and U.S. Patent Nos. 5,299,574, 5,215,540, 5,016,640 and 4,883,058 disclose catheters for use in selective coronary angiography of the right coronary artery. See also U.S. Patent No. 4,033,331. Finally, U.S. Patent No. 4,898,591 discloses a catheter with inner and outer layers containing braided portions. The '591 patent also discloses a number of different shapes for intravascular catheters.

Thus, there are a number of patents which disclose catheters with predetermined shapes, designed for use in specific medical procedures generally associated with the heart or the vascular system. Because of the precise physiology of the heart and the vascular system, catheters or introducers with specifically designed shapes for predetermined uses within the human heart and vascular system are important.

The sources of energy used for catheter ablation vary. Initially, high voltage, direct current (DC) ablation techniques were commonly used. However, because of problems associated with the use of DC current, radio frequency (R.F.) ablation has become a preferred source of energy for the ablation procedures. The use of RF energy for ablation has been disclosed, for example, in U.S. Patent Nos. 4,945,912, 5,209,229, 5,281,218, 5,242,441, 5,246,438, 5,281,213 and 5,293,868. Other energy sources for ablation of heart tissue include laser. ultrasound, microwave and direct current fulgutronization procedures. Also disclosed are procedures where the temperature about the catheterization probe is modified. Catheter ablation is typically performed using a steerable electrode catheter. See, for example, U.S. Patent No. 5,397,304. These catheters are available from a number of manufacturers, for example, Daig, Mansfield Webster, Bard, EP Technologies and Medtronic, each with a variety of deflecting curve options. These steerable catheters are comprised of a long catheter body secured at its proximal end to a control handle. By manipulation of mechanisms within the control handle, the distal tip of the steerable catheter is bent. These steerable catheters are used either alone or in some procedures with certain vascular sheaths. See Heart Disease in Infants, Children and Adolescents , Saul, J.P. "Electrophysiologic Therapeutic Catheterization, pages 452-480 (1995).

Catheter ablation of accessory pathways associated with Wolff-Parkinson-White Syndrome utilizing a long vascular sheath using a transseptal and retrograde approach is discussed in Saul, J.P., et al. "Catheter Ablation of Accessory Atrioventricular Pathways in Young Patients: Use of Long Vascular Sheaths, the Transseptal Approach and a Retrograde Left Posterior Parallel Approach" Journal of the American College of Cardiology. Vol. 21, no. 3, pps. 571-583 (March 1, 1993). See also Swartz, J.F. "Radiofrequency Endocardial Catheter Ablation of Accessory Atrioventricular Pathway Atrial Insertion Sites" Circulation. Vol. 87, no. 2, pps. 487-499 (February, 1993). The use of shaped guiding introducers to direct ablation catheters for treatment of Wolff- Parkinson-White Syndrome is disclosed in U.S. Patent Nos. 5,427,119 and 5,497,774. These patents disclose the use of guiding introducers to guide ablation and mapping catheters to selected locations within the right and left atria for the ablation of reentry circuits associated with atrial arrhythmia including, specifically. Wolff-Parkinson-White Syndrome. These guiding introducers are designed for use in adult hearts. Pediatric hearts present special problems for treatment of cardiac arrhythmia. The size, shape, internal configuration, function and orientation of a pediatric heart changes significantly from the time of birth to puberty. For example, the heart increases in overall size from 7 to 10 times from infancy to adulthood. Consistent with the change in overall size of the heart, size in the chambers of the heart also change dramatically. In addition, the physical orientation of the heart in a child generally changes from birth to puberty. Not only is the heart of a child oriented more horizontally than is an adult's heart, but its relative rotational position also changes. In a child, the inferior portion of the heart rests on the diaphragmatic surface. In addition, the mitral valve is lower in the heart in relation to the tricuspid valve in a child's heart than in an adult heart. The AV valves become larger as the child grows, growing in linear relation to age. The aortic annulus and root also grow and stretch with time leading to a more posterior placement of the aorta within the base of the heart. Further, the valves in a pediatric heart are not as well developed nor are the valve openings as large as in an adult heart, thus limiting the size, shape and complexity of the devices that can be passed through those valves. As a result of all of these anatomical differences, devices which are used in pediatric heart must have a different orientation, size and shape than ones that are designed for use in an adult heart. Wolff-Parkinson-White Syndrome has been identified as a cardiac arrhythmia that sometimes occurs in children. This arrhythmia naturally disappears in some children as they grow older. However, when the arrhythmia is acute, it is often necessary to treat these children, even if they are very young. See Saul, J.P. "Electrophysiologic Therapeutic Catheterization" pp. 452-465. However, because of the size, shape and orientation of pediatric hearts, it is difficult to place an ablation catheter at the correct location for the ablation procedure.

The conventional approach for ablation of surfaces in the heart in an adult is a parallel approach wherein the ablation catheter is introduced within the chamber of the heart parallel to the AV groove. However, due to differences between pediatric and adult hearts, this parallel approach is often not feasible and is particularly difficult in the smaller hearts found in smaller and younger patients. In addition, because of the orientation of the heart and its overall size, it is quite difficult to maintain an ablation catheter at a particular location using this parallel approach. Further, as pediatric hearts naturally beat at a higher rate and with that rate exacerbated when affected by arrhythmia, such as Wolff-Parkinson-White Syndrome, it is difficult to place a flexible catheter at the correct location and maintain it at that location for a sufficient time to monitor and ablate the arrhythmia. In some circumstances, the parallel approach to the left and right AV groove may be limited regardless of the heart size or patient age. Maintenance of a parallel catheter/sheath position is made more difficult by the tendency of the medical device to slide superiorly toward the atria or inferiorly toward the ventricle during the beating of the heart. Thus, there are many circumstances where a perpendicular approach to the AV groove is the preferred approach.

Accordingly, it is an object of this invention to prepare guiding introducers for selected medical procedures in pediatric hearts.

It is a further object of this invention to prepare guiding introducers to guide ablation and mapping catheters for use in selected electrophysiology procedures within a pediatric heart.

Another object of this invention is to prepare guiding introducers for use with ablation catheters in selected ablation procedures within the left and right atria of a pediatric heart.

It is a still further object of this invention to prepare guiding introducers for use with ablation catheters for the treatment of cardiac arrhythmia, such as Wolff-Parkinson-White syndrome in children.

It is a still further object of this invention to prepare guiding introducers for use with ablation catheters wherein a perpendicular approach is utilized in the ablation procedure. These and other objects are obtained by the design of the guiding introducer system disclosed in the instant invention.

SUMMARY OF THE INVENTION The invention includes a series of guiding introducers for selected medical procedures in the left and right atria of a pediatric heart. These guiding introducers are precurved, guiding introducers divided into two or more sections, each with specific shapes designed for use in ablation procedures in either the left or right atrium of a pediatric heart. The pediatric guiding introducers for use in the right atrium guide an ablation and mapping catheters to specific locations around the annulus of the tricuspid valve. The guiding introducers for use in the left atrium guide an ablation and mapping catheters to specific locations around the valve annulus of the mitral valve. The specific shape of the guiding introducers permit the placement of the ablation or mapping catheter at the precise location needed for the required ablation and mapping procedure. In addition, these guiding introducers permit the utilization of a perpendicular approach to the AV groove which offers a number of advantages over the parallel approach, both in smaller hearts of pediatric patients and in small adults and for access to the right AV groove in the anterior and lateral left AV groove in all heart.

The invention also comprises a process for selected medical procedures in the left and right atria of a pediatric heart. The process introduces into the right or left atrium precurved guiding introducer into which an ablation catheter is advanced. The distal tip of the ablation catheter is then extended through the guiding introducer to map and ablate one or more anomalous conduction pathways associated with the right and left atrium of a pediatric heart. The guiding introducers disclosed are particularly adapted for a perpendicular approach to the left and right AV groove in a pediatric heart for an ablation procedure. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a cross-section of the heart showing the use of one of the guiding introducers guiding an ablation catheter to a location posterior to the annulus of the mitral valve. Figure IB is a cross-section of the heart showing the use of one of the guiding introducers guiding an ablation catheter to a location anterior to the annulus of the mitral valve.

Figure 1C is a cross-section of the heart showing the use of one of the guiding introducers guiding an ablation catheter to a location posterior to the annulus of the tricuspid valve.

Figure ID is a cross-section of the heart showing the use of one of the guiding introducers guiding an ablation catheter to a location lateral to the annulus of the tricuspid valve.

Figure 2A is side view of a first embodiment of a guiding introducer for use in the treatment of cardiac arrhythmia in the right atrium of a pediatric heart associated with the valve annulus of the tricuspid valve.

Figure 2B is a side view of the guiding introducer of Figure 2A rotated 90° clockwise from the position of Figure 2A when viewed from the perspective of the proximal end of the guiding introducer.

Figure 3A is a side view of a second embodiment of a guiding introducer for use in the treatment of cardiac arrhythmia in the right atrium of a pediatric heart in a position lateral to the valve annulus of the tricuspid valve.

Figure 3B is a side view of the guiding introducer of Figure 3A rotated 90° clockwise from the position of Figure 3A, when viewed from the perspective of the proximal end of the guiding introducer. Figure 3C is a side view of a portion of the distal end of the guiding introducer of Figure 3A rotated 90° counterclockwise from the position of the guiding introducer shown in Figure 3B when viewed from the proximal end of the guiding introducer.

Figure 4A is a side view of a guiding introducer for use in the treatment of cardiac arrhythmia in the left atrium of a pediatric heart in a position anterior to the valve annulus of the mitral valve.

Figure 4B is a side view of the guiding introducer of Figure 4A rotated 90° clockwise from the position of Figure 4A, when viewed from the perspective of the proximal end of the guiding introducer.

Figure 4C is a side view of a portion of the distal end of the guiding introducer of Figure 4A rotated 90° clockwise from the position of the guiding introducer in Figure 4B. Figure 4D is an end view of the guiding introducer of Figure 4A which has been rotated 90° upward from the position of the guiding introducer in Figure 4B viewed from the perspective of the proximal end of the guiding introducer. Figure 5A is a side view of a second embodiment of a guiding introducer for use in the treatment of cardiac arrhythmia in the left atrium of a pediatric heart in a position posterior to the valve annulus of the mitral valve. Figure 5B is a side view of the guiding introducer of Figure 5A rotated 90° clockwise from the position of Figure 5A, when viewed from the perspective of the proximal end of the guiding introducer. Figure 5C is a side view of a portion of the distal end of the guiding introducer of Figure 5A rotated 90° clockwise from the position of the guiding introducer in Figure 5B.

Figure 5D is an end view of the guiding introducer of Figure 5A which has been rotated 90° upward from the position of the guiding introducer of

Figure 5B viewed from the proximal end of the guiding introducer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A typical pediatric human heart includes a right ventricle, a right atrium, left ventricle and left atrium. See Figures 1A, IB, 1C and ID. The right atrium is in fluid communication with the superior vena cava and the inferior vena cava. The atrioventricular septum separates the right atrium from the right ventricle. The tricuspid valve contained within the atrioventricular septum communicates the right atrium with the right ventricle. On the inner wall of the right atrium where it is connected with the left atrium is a recessed portion, the fossa ovalis. In the heart of a fetus, the fossa ovalis is open, permitting the fetal blood to flow between the right and left atria. In most individuals, this opening closes after birth, but in as many as 25 percent of individuals an opening remains in the fossa ovalis between the right and left atria even after birth. Between the fossa ovalis and the tricuspid valve is the opening or ostium for the coronary sinus. The coronary sinus is the large epicardial vein which accommodates most of the venous blood which drains from the myocardium into the right atrium.

In a normal heart, contraction and relaxation of the heart muscle (myocardium) takes place in an organized fashion as electro-chemical signals pass sequentially through the myocardium from the atrial to the ventricular tissue along a well defined route which includes the His-Purkinje system. Initial electrical impulses are generated at the sinuatrial (SA) node and conducted to the atrioventricular (AV) node. The AV node lies near the ostium of the coronary sinus in the interatrial septum in the right atrium. The His-Purkinje system begins at the AV node and follows along the membranous interatrial septum toward the tricuspid valve through the atrioventricular septum and into the membranous interventricular septum. At about the middle of the interventricular septum, the His- Purkinje system splits into right and left branches which straddle the summit of the muscular part of the interventricular septum. Sometimes abnormal rhythms occur in the heart which are referred to as arrhythmia. A common arrhythmia is reciprocating tachycardia associated with Wolff-Parkinson-White syndrome (W-P-W) . The cause of W-P-W is generally believed to be the existence of an anomalous conduction pathway or pathways that connects the atrial muscle tissue directly to the ventricular muscle tissue, thus bypassing the normal His-Purkinje system. These pathways are usually located in the fibrous tissue that connects the atrium and the ventricle. In recent years a technique has been developed to destroy these anomalous conduction pathways by delivering energy into the tissue in which the pathways exist. To accomplish this procedure an ablation catheter is positioned as close as possible to the anomalous conduction pathway to maintain constant tissue contact while energy is delivered to the cardiac tissue to destroy the pathway. This same type of contact with the cardiac tissue is also necessary when mapping or other such procedures are employed relating to these pathways. One end of these anomalous conduction pathways is generally located either in the right atrium or in the left atrium with the other end of the pathway located in the corresponding ventricle. When the anomalous conduction pathway is located between the left atrium and the left ventricle, there are two approaches to positioning the catheter near the pathway for the appropriate medical procedure. One is to introduce the catheter into the femoral artery by a standard introducer sheath and advance it up the aorta, across the aortic valve into the left ventricle and then attempt to position its tip under the mitral valve annulus near the anomalous conduction pathway. This approach is difficult for many reasons, including the structure of the left ventricle, the fact that it requires arterial access and potential problems associated with ablation of ventricular tissue such as the creation of a substrate for a future arrhythmia which could result in sudden cardiac death. This concern is particularly present when the ablation procedure involves a pediatric heart.

The other alternative approach, which is preferred, is to introduce a transseptal or Mullins sheath apparatus or a long single plane introducer, such as Fast Cath™ transseptal introducer manufactured by Daig Corp., into the right femoral vein and advance it through the inferior vena cava into the right atrium. If the fossa ovalis is not open, a puncture is made through the fossa ovalis in the interatrial septum and the apparatus is advanced into the left atrium where the trocar and dilator of the apparatus are removed, leaving the introducer in position in the left atrium. The mapping or ablation catheter is then inserted through the introducer into the left atrium and is positioned adjacent to the mitral valve annulus near the anomalous conduction pathway. Specific positions may be chosen for the mapping or ablation on the left side of the heart, including posteroseptal, posterior, posterolateral, lateral, anterolateral, and anterior positions around the mitral valve annulus. For example. Figures 1A and IB show ablation procedures posterior and anterior to the mitral valve annulus.

Traditionally, there have also been two techniques for locating and ablating anomalous conduction pathways which are situated between the right atrium and right ventricle. Either method can be initiated by advancing a catheter through an access site into a vein in the leg, neck or upper chest.

The first technique, which approaches the pathway from the pathway's ventricular insertion site, involves entering the right atrium from either the inferior or superior vena cava, passing through the tricuspid valve, and advancing toward the apex of the right ventricle. The catheter tip then must make a 180° turn to reverse its path back up toward the right atrium and locate the accessory pathway under the tricuspid valve apparatus. The accessory pathway is then ablated from the ventricular insertion site under the tricuspid valve.

The second technique, which is preferred, approaches the pathway from the atrial insertion site. Using this technique, the right atrium is entered through the inferior or superior vena cava, and the accessory pathway around the tricuspid valve annulus is located from the atrial side. The accessory pathway is then ablated on the atrial aspect of the tricuspid valve. For example, Figures 1C and ID show ablation procedures anterior and lateral to the tricuspid valve annulus. Ablation procedures are more difficult in pediatric hearts than in adult hearts because of the significant differences between these types of hearts. These differences include the smaller size of the pediatric heart, its varied shape, its changing internal configuration, function and orientation. In addition, because the size of the chambers and valves are smaller, it is more difficult for an ablation catheter to approach the valve annulus to perform ablation procedures. The conventional processes for the ablation procedure normally utilize a parallel approach to the right and left AV groove. This approach may not be effective and may not even be feasible with a pediatric heart, depending on its size and orientation. It has been discovered that for certain smaller hearts, including pediatric hearts, a perpendicular approach to the AV groove offers a number of advantages. These advantages include stability against dislodgement by valve movement, lack of necessity for containment of the catheter or sheath within a small valve ring, the availability of side-to-side and longitudinal movement along the AV groove and the ability of using the ablation catheter in any chamber size from the very smallest to the largest heart.

Guiding introducers such as those disclosed in U.S. Patent No. 5,497,774 and 5,427,119 are designed for use with adult hearts. Because of the size and orientation of the chambers and the valves in pediatric hearts, these guiding introducers cannot easily be used to place ablation catheters in the appropriate position around the valve annulus to perform ablation procedures. There is not sufficient space within the chambers of a pediatric heart to allow this type of positioning. The processes disclosed in these patents also are designed for a parallel approach to the AV groove for the ablation procedure. Such approach is not feasible with certain very small hearts that are present in small children or small adults. Mere introduction of the catheter into the left or right atrium is not sufficient to effectively and efficiently perform these medical procedures, especially the mapping or ablation of anomalous conduction pathways. These medical procedures are usually performed using a specific ablation and mapping catheter. The medical practitioners monitor the introduction of the catheter and its progress through the vascular system by a fluoroscope. However, such fluoroscopes do not easily identify the specific features of the heart, in general, and the critically important structures of the left or right atria of a pediatric heart in specific, thus making placement of the catheter difficult. This placement is especially difficult as the beating heart is in motion and the catheter will be moving within the atria as blood is being pumped through the heart throughout the procedure. The placement of the catheter in a pediatric heart is even more difficult because the rate of heart beat even in a normal pediatric heart is higher than in an adult heart and this rate often increases significantly as a result of cardiac arrhythmia. The structure and shape of the disclosed guiding introducers address and solve these problems, making placement of the ablation and mapping catheter easier and more precise.

The first guiding introducer for use in the right atrium of a pediatric heart is comprised of a first and second sections. See Figures 2A and 2B. (Each section is preferably formed as an integral portion of the entire guiding introducer without discreet divisions. However, the division of the guiding introducer into different sections better illustrates the overall shape of the guiding introducer. For this first embodiment, the guiding introducer will be shown in two views. In each such view, the shape of each section of the guiding introducer will be described, making reference to its position as shown in the first of the figures. In the second figure, the guiding introducer is rotated clockwise 90° about an axis of the first section of the guiding introducer when viewed from the perspective of the proximal end of the guiding introducer. Other guiding introducers are described using three or four views where the guiding introducer is further rotated.) The first section of the first guiding introducer for use in the right atrium is a conventional, generally elongated hollow straight section of sufficient length for introduction into the patient and for manipulation from the point of insertion to the specific desired location within the heart. Because the guiding introducer is used for pediatric hearts, the overall usable length is preferably from about 15 to about 25 inches. Merged with the distal end of the first section of the guiding introducer, but an integral part of the entire guiding introducer, is the second section comprising a curved portion followed by a straight portion. The curved portion curves with a radius of about 0.2 to about 1.0 inch, preferably from about 0.3 to about 0.8 inches and most preferably from about 0.4 to about 0.6 inches in an arc of about 100 to about 170°, preferably from about 120 to about 150° and most preferably about 130 to about 140°. At the distal end of the curved portion is the straight portion which is less than about 2.0 inches in length, preferably from about 0.1 to about 1.0 inch and most preferably about 0.3 to about 0.5 inch ending in the distal tip. This first guiding introducer, which guides an ablation or mapping catheter into the right atrium of a pediatric heart, is for use around the right anterior medial to right anterolateral portions of the annulus of the tricuspid valve.

The second guiding introducer for use in the right atrium is comprised of a first, second and third sections. See Figures 3A, 3B and 3C. Figure 3C is rotated an additional 90° from its position in Figure 3B. The first section is a conventional, generally elongated, hollow straight section of sufficient length for introduction into the patient and for manipulation from the point of insertion to the specific desired location within the heart. Because this introducer is designed for use with pediatric hearts, the overall usable length of the introducer is preferably from about 15 to about 25 inches. Merged with the distal end of the first section of the guiding introducer, but an integral part of the overall guiding introducer, is the second section which is comprised of a curved portion and a straight portion, wherein the curved portion curves in a radius of about 0.2 to about 1.0 inch, preferably from about 0.3 to about 0.8 inch and most preferably from about 0.4 to about 0.6 inches to form an arc of approximately 20 to about 70°, preferably from about 30 to about 60° and most preferably about 40 to about 50°. At the end of this curved portion is the straight portion which is from about 0.4 to about 1.5 inch, preferably about 0.5 to about 1.0 inch and most preferably from about 0.5 to about 0.8 inches in length. (The curved and straight portion comprising the second section are best shown in Figure 3B.) The third section, best shown in Figure 3C, begins at the distal end of the second section and is comprised of a second curved portion and a second straight portion. This second curved portion curves away from the second section in a radius of about 0.2 to about 1.0 inches, preferably from about 0.3 to about 0.8 inch and most preferably from 0.4 to about 0.6 inches, to form an arc of about 110 to about 160°, preferably from about 120 to about 150° and most preferably about 130 to about 140°. At the distal end of this second curved portion is the second straight portion which is less than about 1.0 inches in length, preferably from about 0.1 to about 0.8 inches and most preferably from about 0.3 to about 0.5 inches in length ending in the distal tip of the guiding introducer. In a preferred embodiment, the third section forms a plane which curves out of a plane formed by the first and second sections at an angle from about 90 to about 170°, preferably from about 120 to about 150° and most preferably from about 130 to about 140°. See Figure 3C. This second guiding introducer is designed to guide a mapping or ablation catheter to the lateral portion of the annulus of the tricuspid valve in the right atrium of a pediatric heart. In addition to two guiding introducers for use in the right atrium, two additional guiding introducers are designed for use in the left atrium for ablation procedures around the mitral valve, specifically anterior to the mitral valve (Figures 4A, 4B, 4C and 4D) and posterior to the mitral valve (Figures 5A, 5B, 5C and 5D) . Each of these catheters has a multiplanar shape.

The first guiding introducer for use in the left atrium is comprised of a first, second and third sections. The first section is a conventional, generally elongated, hollow straight section of sufficient length for introduction into the patient and for manipulation from the point of insertion to the desired location within the heart. The overall usable length of this introducer is from about 15 to about 25 inches. Merged with the distal end of the first section of the guiding introducer, but an integral part of the guiding introducer, is the second section which is best shown in Figure 4B, which comprises a curved section. As shown in Figure 4B that section curves to the right in an angle of about 15 to about 75°, preferably from about 25 to about 65° and most preferably from about 30 to about 60° with a radius of about 0.2 to about 1.0 inch, preferably from about 0.3 to about 0.7 inches and most preferably from about 0.4 to about 0.6 inches. The third section follows the second section and is comprised of a compound curved portion followed by a straight portion. The compound curved portion first curves to the left as shown in Figure 4A with a radius of about 0.2 to about 1.0 inches, preferably from about 0.3 to about 0.7 inches and most preferably from about 0.4 to about 0.6 inches with an arc of about 135 to about 215°, preferably from about 160 to about 200° and most preferably from about 170 to about 190°, followed by a second curve to the left as shown in Figure 4B with a radius of about 0.2 to about 1.0 inch, preferably from about 0.3 to about 0.7 inches and most preferably from about 0.4 to about 0.6 inches with an arc of about 5 to about 45° and preferably from about 15 to about 35° ending in the straight section, which is less than about 0.5 inches in length, ending in the distal tip. This compound curve section is also shown by reference to Figure 4D. The compound curve section is based on a circle shown in Figure 4D which has a radius of about 0.6 to 1.4 inches, preferably from about 0.8 to 1.2 inches. The compound curve follows the radius of the circle with an arc to the left. (A similar compound curvature is contained within the second guiding introducer for the left atrium and is shown in Figure 5D.) As shown in Figures 4B and 4D, this third section is curved away from an extension of the first section about 0.1 to about 0.5 inches and preferably from about 0.1 to about 0.3 inches. In addition, the overall distance of the distal tip of the introducer from the first straight section is from about 0.7 to about 2.0 inches, preferably from about 0.8 to about 1.2 inches.

The second guiding introducer for use in the left atrium is shown in Figures 5A, 5B, 5C and 5D and is comprised of a first, second and third sections. It is designed for use for ablation procedures performed anterior to the mitral valve in pediatric hearts. The structure is similar to the guiding introducer disclosed in Figures 4A through 4D, but a mirror image thereof. The first section thereof is a conventional, generally elongated, hollow straight section of sufficient length for introduction into the patient and for manipulation from the point of insertion to the specific desired location within the heart. The preferred overall length is about 15 to about 25 inches. Merged with the distal end of the first section of the guiding introducer is the second section which is comprised of a curved section curving to the right (as shown in Figure 5B) with a radius of about 0.2 to about 1.0 inches, preferably from about 0.3 to about 0.7 inches and most preferably about 0.4 to about 0.6 inches with an arc of about 15 to about 75°, preferably from about 25 to about 65° and most preferably from about 30 to about 60°. See Figures 5B and 5D. The third section is a compound curved section followed by a straight portion with the curved portion curving first to the right as shown in Figure 5A with a radius of about 0.2 to about 1.0 inch, preferably from about 0.3 to about 0.7 inches and most preferably from about 0.4 to about 0.6 inches with an arc of about 135 to about 215°, preferably from about 160 to about 200° and most preferably from about 170 to about 190° followed by a second curved portion curving to the left as shown in Figure 5B with a radius of about 0.2 to about 1.0 inches, preferably about 0.3 to about 0.7 inches and most preferably from about 0.4 to about 0.6 with an arc of about 5 to about 45° and preferably from about 15 to about 35°. This third section is offset from an extension of the first section as shown in Figures 5B and 5D in an amount of about 0.1 to about 0.5 inch and preferably from about 0.1 to about 0.3 inch. The straight portion is preferably less than about 0.5 inches in length ending in the distal tip of the second guiding introducer. The overall distance of the distal tip of the introducer from the first straight section is from about 0.7 to about 2.0 inches, preferably from about 0.8 to about 1.5 inches and most preferably from about 0.8 to about 1.2 inches. If this position of the third section is rotated 180° from its position in Figure 5B about a vertical axis passing through the first section, the second and third sections would be directed to the left of the first section as shown in Figure 4B. While the above described shapes are preferred, the shape of the sections of the guiding introducer may be modified by use of one or more straight or curved sections as long as the overall, general shape of the guiding introducer is approximately as described above. In addition, the particular order of curves and straight sections may be changes as long as the overall curvature of the guiding introducer delivers the mapping and ablation catheter to approximately the same location as the guiding introducer above described as the preferred embodiment. Further, one or more curves of the instant application may be combined or split into additional curved or curved and straight sections as long as the general overall shape of the precurved, guiding introducer is maintained. The critical design feature of the guiding introducer is that it provides a stable platform supported by the cardiac anatomy to permit an ablation or mapping catheter to be advanced and withdrawn without the need for repeated repositioning the guiding introducer. The distal tip of these guiding introducers may be, and generally is tapered to form a good transition with a dilator.

The guiding introducer may be made of any material suitable for use in humans, which has a memory or permits distortion from, and subsequent substantial return to, the desired three dimensional or complex multi-planar shape. For the purpose of illustration and not limitation, the internal diameter of the tip of the guiding introducers may vary from about 6 to about 10 "French". (One "French" unit equals about one third of a millimeter.) Such guiding introducers can accept dilators from about 6 to about 10 French and appropriate guidewires. Obviously if larger, or smaller dilators and catheters are used in conjunction with the guiding introducers of the instant invention, modification can be made in the size of the guiding introducers.

The guiding introducers preferably contain one or a multitude of radiopaque tip marker bands near the distal tip of the guiding introducers. Various modifications may be made in the shapes by increasing or decreasing its size or adding additional tip markers.

The guiding introducers also preferably contain one or a plurality of vents near the distal tip of the guiding introducers, preferably 3 or 4 of such vents. The vents are preferably located no more than about 2 to 3 inches from the tip of the guiding introducers and more preferably 0.1 to about 2.0 inches from the distal tip. The size of these vents should be in the range of about 20 to 60 1/1000 of an inch in diameter. These vents are generally designed to prevent air embolisms from entering the guiding introducers caused by the withdrawal of a catheter contained within the guiding introducers in the event the distal tip of one of the guiding introducers is occluded. For example, if the tip of one of the guiding introducers is placed against the myocardium and the catheter located within the guiding introducer is withdrawn, a vacuum may be created within the guiding introducer if no vents are provided. If such vacuum is formed, air may be forced back into the guiding introducer by the reintroduction of a catheter into the lumen of the guiding introducers. Such air embolism could cause problems to the patient including the possibility of a stroke, heart attack or other such problems common with air embolisms in the heart. The addition of vents near the distal tip of the guiding introducers prevents the formation of such vacuum by permitting fluid, presumably blood, to be drawn into the lumen of the guiding introducers as the catheter is being removed, thus preventing the possibility of formation of an air embolism. Variances in size and shape of the guiding introducers are intended to encompass various sizes and shapes of pediatric hearts. While pediatric ablation procedures are generally not performed on children less than about 2 years of age, under extreme situations such ablation procedures may be conducted which might require reductions in the size and shape of elements of these guiding introducers. However, the overall shape of the guiding introducers will be maintained.

In operation, a modified Seldinger technique is used for the insertion of a catheter into the appropriate vasculature of the body. The appropriate vessel is accessed by needle puncture. A soft, flexible tip of an appropriate sized guidewire is then inserted through and a short distance beyond the needle into the vessel. Firmly holding the guidewire in place, the needle is removed. The guidewire is then advanced through the vessel into the right atrium. With the guidewire in place, the dilator is then placed over the guidewire with the guiding introducer placed over the dilator. The dilator and guiding introducers generally form an assembly to be advanced together along the guidewire into the right atrium. After insertion of the assembly, the guidewire is then withdrawn. The ablation procedure may proceed at this point if the desired ablation activities are in the right atrium. If so, a catheter to be used for treatment of the anomalous conduction pathway in the right atrium is advanced through the lumen of the guiding introducer and is placed at the appropriate location near the tricuspid valve annulus. Because of the shape of the guiding introducer, the tip of the ablation catheter approaches the particular location for the ablation procedure at a generally perpendicular angle as shown, for example, in Figures 1C or ID. Following completion of the ablation procedure, both the ablation catheter and the guiding introducer are withdrawn.

If the ablation procedure is necessary in the left atrium, after the guiding introducer is directed into the right atrium, a Brockenbrough or trocar needle is then inserted through the lumen of the dilator to the right atrium to create an opening through the interatrial septum, preferably at the fossa ovalis. After the opening is made through the interatrial septum, the needle, dilator and the guiding introducer are advanced into the left atrium. After the guiding introducer is advanced through the interatrial septum into the left atrium, the Brockenbrough or trocar and dilator are removed, leaving the guiding introducer in the left atrium. The catheter to be used for analysis and/or treatment of the anomalous conduction pathways is then advanced through the lumen of the guiding introducer and is placed at an appropriate location near the mitral valve annulus. By extending the distal tip of the ablation catheter from the guiding introducer, it will approach the mitral valve annulus at an angle of approximately 90°, thus permitting ablation procedures to be performed around the mitral valve as shown for example in Figures 1A and IB.

By the guiding introducer providing sufficient rigidity, the distal end of the catheter can be maintained in a fixed location or surface position of the endocardial structure to permit the appropriate procedures to be performed. If sensing procedures are involved, the desired guiding introducer is first placed in the desired location. At that point, the electrical activity of the heart peculiar to that location can be precisely determined by use of an electrophysiology catheter placed within the guiding introducer. Further, as the guiding introducers permit precise location of catheters, an ablation catheter may then be placed at the precise location necessary for destruction of the cardiac tissue by the use of energy, for example, radio frequency, thermal, laser or direct current (high energy direct, low energy direct and fulgutronization procedures) . The precise placement of the ablation catheter tip on the cardiac tissue is important as there will be no dilution of the energy delivered due to unfocused energy being dissipated over the entire cardiac chamber and lost in the circulating blood by a constant movement of the tip of the ablating catheter. This permits a significantly reduced amount of energy to be applied, while still achieving efficient ablation. Further, time used to perform the procedure is significantly reduced over procedures where no guiding introducers are used.

It will be apparent from the foregoing that while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that this invention be limited except as by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A guiding introducer for use in the mapping and ablation of anomalous conduction pathways in a pediatric heart around a mitral and tricuspid valves comprising an introducer shaped to fit into atria of a pediatric heart comprising straight or curved sections.

2. The guiding introducer of Claim 1 comprising a first and second sections, wherein the first section is a generally elongated, straight section, wherein merged with said first section is the second section, comprising a curved portion and a straight portion.

3. The guiding introducer of Claim 2 wherein the curved portion curves with a radius of about 0.2 to about 1.0 inch to form an arc of approximately 100 to about 170┬░, and wherein the straight portion is from about 0.1 to about 1.0 inch in length.

4. The guiding introducer of Claim 1 comprising a first, second and third sections.

5. The guiding introducer of Claim 4 wherein the first section comprises a generally elongated straight section, wherein merged with the first section is the second section comprising a curved portion and a straight portion, wherein the curved portion curves with a radius of about 0.2 to about 1.0 inch to form an arc of about 20 to about 70┬░ and wherein the straight portion is from about 0.4 to about 1.5 inch in length.

6. The guiding introducer of Claim 4 wherein merged with the second section is the third section comprising a second curved portion and a second straight portion, wherein the radius of the second curved portion is about 0.2 to about 1.0 inch to form an arc of about 110 to about 160┬░, and wherein the second straight portion is less than about 1.0 inch in length.

7. The guiding introducer of Claim 4 wherein the first section comprises a generally elongated straight section, wherein merged with the first section is the second section which comprises a curved section curving with a radius of about 0.2 to about 1.0 inch to form an arc of about 20 to about 70┬░.

8. The guiding introducer of Claim 7 wherein the third section comprises a compound curved portion and a straight portion, wherein the compound curved portion curves with a radius of about 0.2 to about 10 inches to form an arc of about 135 to about 215┬░, and also curves with a radius from about 0.2 to about 1.0 inch to form an arc of about 5 to about 45┬░, and wherein the straight portion is less than about 0.5 inches in length.