Guiding introducers for use in the treatment of left ventricular tachycardia

A process for the treatment of ventricular tachycardia in the left ventricle using a retrograde approach by use of ablation and/or mapping catheters guided by precurved guiding introducers. Also disclosed are predetermined shapes for the guiding introducers to be used for the treatment of ventricular tachycardia in the left ventricle using a retrograde approach.

BACKGROUND OF INVENTION 
1. Field of Invention 
This invention relates to introducers. More particularly, this invention 
relates to guiding introducers of specific shapes for use within the left 
ventricle of the human heart for the treatment of left ventricular 
tachycardia. 
2. Prior Art 
Introducers and catheters have been in use for medical procedures for many 
years. For example, one use has been to convey an electrical stimulus to a 
selected location within the human body. Another use is to monitor and 
make measurements for diagnostic tests within the human body. Catheters 
may be used by a physician to examine, diagnose and treat while positioned 
at a specific location within the body which is otherwise inaccessible 
without more invasive procedures. In use, catheters may be inserted into a 
major vein or artery which is near the body surface. These catheters are 
then guided 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 the 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 
other body part to arrive at the specified location. Further, the catheter 
must not be so rigid as to cause damage to the artery or vein while it is 
being moved within the body. 
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 veins or arteries and then is positioned at a specified location 
within 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 in 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 the desired 
location within the heart or in the arteries or veins associated with the 
heart. For example, U.S. Pat. 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. Pat. No. 5,231,994 discloses a 
guide catheter for guiding a balloon catheter for the dilation of coronary 
arteries. U.S. Pat. No. 4,117,836 discloses a catheter for the selective 
coronary angiography of the left coronary artery and U.S. Pat. Nos. 
5,215,540, 5,016,640 and 4,883,058 disclose catheters for selective 
coronary angiography of the right coronary artery. U.S. Pat. No. 5,242,441 
discloses a deflectable catheter for ablation procedures in the 
ventricular chamber. See also U.S. Pat. No. 4,033,331. In addition, U.S. 
Pat. No. 4,898,591 discloses a catheter with inner and outer layers 
containing braided portions. The '591 patent also discloses a number of 
different curvatures for intravascular catheters. Thus, there are a number 
of references which disclose catheters with predetermined shapes, designed 
for use during specific medical procedures generally associated with the 
heart or the vascular system. Because of precise physiology of the heart 
and the vascular system, catheters or introducers with precisely designed 
shapes for predetermined uses within the human heart and vascular system 
are increasingly important. 
Catheter ablation of accessory pathways using a long vascular sheath by 
means of a transseptal or 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" J. Amer. Coll. Card., Vol. 
21, no. 3, pps 571-583 (Mar. 1, 1993). See also Swartz, J. P. 
"Radiofrequency Endocardial Catheter Ablation of Accessory 
Atrioventricular Pathway Atrial Insertion Sites" Circulation, Vol. 87, no. 
2, pps. 487-499 (February, 1993). 
U.S. Pat. No. 4,641,649 discloses the use of high frequency energy for the 
treatment of tachycardia or cardiac dysrhythmia. See also U.S. Pat. Nos. 
5,246,438 and 4,945,912 for the use of radio frequency energy for ablation 
of cardiac tissue. In addition, various articles have disclosed the 
ablation of specific locations within the heart by use of energy, in 
particular, radio frequency energy. See, for example, Gallagher, J. J. et 
al. "Catheter Technique for Closed-Chest Ablation of the Atrioventricular 
Conduction System" N. Engl. J. Med. Vol. 306, pp. 194-200 (1982); 
Horowitz, L. N. "Current Management of Arrhythmia" pp. 373-378 (1991); 
Falk, R. H. et al. "Atrial Fibrillation Mechanics and Management" pp. 
359-374 (1992); and Singer, I. "Clinical Manual of Electrophysiology" pp. 
421-431 (1993). 
In addition, U.S. Pat. No. 5,172,699 discloses a general process for the 
identification and ablation of ventricular tachycardia sites. See also 
U.S. Pat. Nos. 5,222,501 and 5,242,441. 
In addition, the use of radio frequency ablation energy for the treatment 
of Wolff-Parkinson-White Syndrome in the left atrium by use of a 
transseptal sheath is disclosed in Swartz, J. F. et al. "Radiofrequency 
Endocardial Catheter Ablation of Accessory Atrioventricular Pathway Atrial 
Insertion Sites" Circulation 87:487-499 (1993). See also Tracey, C. N. 
"Radio Frequency Catheter Ablation of Ectopic Atrial Tachycardia Using 
Paced Activation Sequence Mapping" J. Am. Coll. Cardiol. 21:910-917 
(1993). 
Accordingly, it is an object of this invention to prepare a guiding 
introducer for selected medical procedures in the left ventricle. 
It is a further object of this invention to prepare a guiding introducer 
for use in selected electrophysiology procedures within the left ventricle 
of the heart. 
Another object of this invention is to prepare a guiding introducer for use 
in selected ablation procedures within the left ventricle of the heart. 
It is a still further object of this invention to prepare a guiding 
introducer for use in the selected ablation of sites in the left ventricle 
of the heart for the treatment of left ventricular tachycardia. 
These and other objects are obtained by the design of the guiding 
introducers disclosed in the instant invention. 
SUMMARY OF INVENTION 
The instant invention includes a process for the treatment of ventricular 
tachycardia within the left ventricle of the heart comprising 
(a) introducing into the left ventricle a precurved, guiding introducer, 
wherein said guiding introducer contains a lumen running lengthwise 
therethrough, a proximal and a distal end and wherein the introducer is 
comprised of shaped first, second and third sections; 
(b) introducing into the lumen of the guiding introducer an ablation and/or 
mapping catheter containing a proximal and distal end, wherein said 
catheter has one or more electrodes located at or near the distal end of 
the catheter; 
(c) guiding the catheter to a selected location within the left ventricle 
by use of the guiding introducer; and 
(d) mapping and/or ablating the selected location within the left ventricle 
by use of the electrodes of the catheter. In addition, the instant 
invention is a guiding introducer to be used in the left ventricle for 
treatment of ventricular tachycardia comprising a first, second and third 
sections.

DESCRIPTION OF THE INVENTION 
A typical human heart includes a right ventricle, a right atrium, left 
ventricle and left atrium. The right atrium is in fluid communication with 
the superior vena cava and the inferior vena cava. The atrioventricular 
septum separates the atria from the ventricles. The tricuspid valve 
contained within the atrioventricular septum communicates the right atrium 
with the right ventricle. The mitral valve contained within the 
atrioventricular septum communicates the left atrium with the left 
ventricle. On the inner wall of the right atrium, where it is connected 
with the left atrium, is a recessed portion, the fossa ovalis. Between the 
fossa ovalis and the tricuspid valve is the opening or ostium for the 
coronary sinus. The coronary sinus is a large epicardial vein which 
accommodates most of the venous blood which drains from the myocardium 
into the right atrium. 
In the normal heart, contraction and relaxation of the heart muscle 
(myocardium) takes place in an organized fashion as electrochemical 
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 electric 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. For example, patients diagnosed with Wolff-Parkinson-White 
syndrome have an arrhythmia, the cause of which is believed to be the 
existence of an anomalous conduction pathway or pathways that connect the 
atrial muscle tissue directly to the ventricular muscle tissue, thus 
by-passing the normal His-Purkinje system. These pathways are usually 
located in the fibrous tissue that connect the atrium and the ventricle. 
Another arrhythmia is ventricular tachycardia ("V.T."). VT is a disease of 
the heart in which the heart's normal arrhythmic contraction is altered. 
Frequently, the rate of heart beat is too fast although the conditions of 
the disease itself are generally quite complex. VT occurs most often in 
patients following a myocardial infarction. A myocardial infarction, 
commonly referred to as a heart attack, is a loss of blood to a region of 
the heart causing the myocardial tissue in that region to die and be 
replaced by an area of scar tissue known as a myocardial infarct. 
Frequently, the myocardial infarct is present in the left ventricle. 
As a result of the myocardial infarct, circular pathways ("reentry 
circuits") are frequently created within the left ventricle for the 
conduction of the electrical impulses of the heart. These reentry circuits 
cause the electrical impulses of the heart to travel in circles about the 
myocardial infarct, frequently causing an erratic and sometimes 
accelerated beating of the heart. These reentry circuits may also occur 
around discrete elements of the heart, such as valves. In addition, the 
reentry circuits sometime occur around both the myocardial infarct and the 
discreet elements of the heart. 
In the past VT has been treated by the use of drugs such as lidocaine, 
quinidine and procainamide. More recently, beta-blocking drugs have been 
used for its treatment. In cases where drug therapy has been ineffective, 
surgical procedures have been used to excise the tissue causing the 
arrhythmia. The procedure involves the removal of a portion of the heart 
muscle, particularly that portion around which the reentry circuit has 
formed. By the excision of this portion of the heart muscle, scar tissue 
is formed which prevents the reformation of the reentry circuit. Obviously 
such procedures are high risk, frequently requiring prolonged periods of 
hospitalization and recuperation. As an alternative to these procedures, 
ablation devices have been used for the diagnosis and treatment of cardiac 
arrhythmias including, specifically, VT. See, for example, U.S. Pat. No. 
5,222,501. 
Ablation procedures, however, are frequently unsuccessful unless repeated 
many times. It is presumed that one reason for the difficulty of ablation 
of ventricular tissue for the treatment of VT is the failure to destroy 
completely the reentry circuit in the ventricular tissue because of the 
inherent thickness of the ventricular tissue and the size of the reentry 
circuit itself. To effectively ablate the ventricular tissue, the ablation 
catheter must be positioned precisely within the ventricle and maintained 
in contact with the ventricular tissue throughout the ablation procedure. 
Such procedures may require the ablation electrode of the ablation 
catheter to remain in contact with the ventricular tissue for a period of 
time well over a minute. This is particularly difficult when the heart is 
beating, sometimes irregularly, during the entire ablation procedure. 
Thus, it is critical that the ablation electrode be maintained at the 
desired location and also be constrained from movement throughout the 
ablation procedure. 
There is generally only one effective approach to the positioning of an 
ablation catheter in the left ventricle for ablation procedures. This 
approach is to introduce the catheter into the femoral artery using a 
standard introducer and advance it up the aorta, across the aortic valve 
into the left ventricle and then position its electrode adjacent to the 
wall of the left ventricle which is near the reentry circuits. This is 
commonly referred to as the "retrograde" approach. The mapping or ablation 
catheter is then inserted through the guiding introducer into the left 
ventricle and positioned adjacent to the wall of the left ventricle near 
the reentry circuits. Specific locations are chosen for the mapping or 
ablation of the ventricular tissue, including specifically locations on 
the lateral freewall, posterior freewall, septal wall and anterior 
freewall. 
Mere introduction of the ablation and mapping catheter into the left 
ventricle for a retrograde approach is not sufficient to effectively and 
efficiently perform the ablation procedures on the reentry circuits. The 
medical practitioner commonly monitors the introduction of the catheter 
and its progress through the vascular system by a fluoroscope. Such 
fluoroscopes can not easily identify the specific features of the heart in 
general, and the critically important structures of the left ventricle in 
specific, thus making placement of the ablation electrode difficult. This 
placement is especially difficult as the beating heart is in motion. In 
addition, the catheter will be moving within the left ventricle as blood 
is being pumped through the heart throughout the procedure. The guiding 
introducers of the instant invention address and solve these problems. 
Referring now to FIGS. 2 through 5, the guiding introducer of the present 
invention for use in the left ventricle for the treatment of VT is 
comprised of first, second and third sections. (Each section is preferably 
formed as an integral portion of the entire guiding introducer without 
discrete divisions. However, the division of the guiding introducer into 
three different sections better illustrates the overall shape of the 
guiding introducers.) Each of the guiding introducers will be shown in 
either two or three views. In each of the views for ease of analysis, the 
guiding introducer will be secured to a valve for attachment to a 
conventional side port tubing and stop cock. In each such arrangement, the 
shape of the guiding introducer and each of its sections will be 
described, making reference to its position in relation to the side port 
and side port tubing where the proximal end of the guiding introducer is 
secured to the side port tubing. In the first referenced figure of each 
embodiment (FIGS. 2A, 3A, 4A and 5A), the side port tubing is generally 
viewed as if it is behind the first section of the guiding introducer. The 
remaining drawings of each embodiment will show the guiding catheter after 
rotation of the guiding introducer about the axis of one of the sections 
of the guiding introducer. Each will focus upon the curved portions of the 
second and third sections. In particular, each will focus on the curved 
portion of the third section and the extent it is curved away from the 
plane of the first two sections when viewed from the side of the guiding 
introducer, such that the first and second sections are merged into a 
single plane as shown in FIGS. 2B, 3B, 4B and 5B. 
The first section in each embodiment of the guiding introducers is the same 
general shape. The first section is a conventional, generally elongated 
hollow, straight introducer 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 overall length of the 
first section as shown in the drawings has been reduced for ease of 
viewing.) 
Merged with the distal end of the first section of the guiding introducer 
is the second section which is a smooth, generally flat curve, curving to 
the left as shown in FIGS. 2A, 3A, 4A and 5A. The extent of the curve of 
this second section is the same in the guiding introducers of FIGS. 2A and 
3A and also the same in FIGS. 4A and 5A. However, the extent of the curve 
in FIGS. 2A and 3A is greater than the curve shown in FIGS. 4A and 5A. The 
curve of FIGS. 2A and 3A has a radius of from about 1.0 in. to about 2.0 
in. and preferably from about 1.3 in. to about 1.7 in. The extent of the 
arc of the curve is from about 190 to about 230 degrees and preferably 
from about 200 to about 220 degrees of arc. The curve of the second 
section of the guiding introducer as shown in FIGS. 4A and 5A also has a 
radius of from about 1.0 in. to about 2.0 in. and preferably from about 
1.3 in. to about 1.7 in. However, the extent of the arc of the curve as 
shown in FIGS. 4A and 5A is reduced from that in FIGS. 2A and 3A from 
about 160 to about 200 degrees and preferably from about 170 to about 190 
degrees of arc. The first and second sections of each of the four guiding 
introducers are generally coplanar (within about 15 degrees of coplanar). 
The third section of each guiding introducer is merged with the distal end 
of the second section of each guiding introducer. The structure of the 
third section of the guiding introducer will depend on the location in the 
left ventricle being treated. As previously stated, the guiding 
introducers are used to place a mapping or ablating catheter in a precise 
position in the left ventricle for treatment of VT by application of an 
ablation and mapping catheter to the septal wall, anterior freewall, 
lateral freewall or posterior freewall. (See, for example, FIGS. 1A and 
1B.) To accomplish these procedures, the third section is comprised of a 
generally straight portion merged with a curved portion. The straight 
portion of the first two embodiments as shown in FIGS. 2A and 3A, is from 
about 1.0 in. to about 2.5 in. in length and preferably from about 1.5 to 
about 2.0 in. in length. The straight portion of the third section of the 
third and fourth embodiments of the guiding introducers as shown in FIGS. 
4A and A is from about 2.0 in. to about 3.0 in. and preferably from about 
2.5 in. to about 3.0 in. in length. In all four embodiments, the straight 
portion is generally coplanar with the first and second sections (within 
about 15 degrees of coplanar). 
In the first embodiment the curved portion of the third section curves to 
the left (as shown in FIG. 2A) away from the first section, in a smooth 
curve with a radius of about 0.5 to about 1.5 in. and preferably about 0.8 
to about 1.2 in. This curved portion curves in an arc from about 70 to 
about 110 degrees and preferably from about 80 to about 100 degrees of arc 
away from the straight portion as shown in FIG. 2A. This curved portion 
may also curve out of plane with the first and second sections from about 
45 degrees clockwise to about 45 degrees counterclockwise when viewed from 
the proximal end of the first section. By adjusting the extent of the 
curve of the curved portion of the third section out of plane with the 
first and second sections, the guiding introducer can direct the ablation 
catheter to cover a significant portion of the wall of the left ventricle. 
This curved portion extends about 0.6 to about 1.5 in. away from the 
straight section and preferably about 0.8 to about 1.2 in. away from the 
straight section. This first embodiment is designed for use in the 
treatment of tachycardia on the septal wall of the left ventricle, 
sometimes referred to as Belhassen Tachycardia. See FIG. 1A. 
The distal tip of all of the guiding introducers may be, and preferably 
will be, tapered to form a good transition with a dilator. This tapering 
is preferably less than 10.degree. and more preferably about 4.degree. to 
about 7.degree.. The guiding introducers preferably may also contain one 
or a multitude of radiopaque tip marker bands near the distal tip of the 
guiding introducer. These guiding introducers also preferably contain one 
or a plurality of vents near the distal tip of the guiding introducer, 
preferably three or four such vents. The vents are preferably located no 
more than about 1.00 in. from the tip of the guiding introducer and more 
preferably 0.10 to about 1.00 in. from the tip. The size of these vents 
should be in the range of about 40 to about 60/1000 of an inch in 
diameter. These vents are generally designed to prevent air from entering 
the guiding introducer caused by the withdrawal of the catheter contained 
within the guiding introducer in the event the distal end of the guiding 
introducer is occluded. For example, if the tip of the guiding introducer 
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 introducer. Such air could cause 
significant problems in the patient, including the possibility of a 
stroke, heart attack or other such problems common with air embolisms. The 
addition of vents near the distal tip of the guiding introducer prevents 
the formation of such vacuum by permitting fluid, presumably blood, to be 
drawn into the lumen of the guiding introducer as the catheter is being 
removed from the guiding introducer, thus preventing air from entering the 
guiding introducer. 
The guiding introducers may be made of any material suitable for use in 
humans which has a memory or permits distortion from, and substantial 
return to, the desired three dimensional or complex multiplanar shape. For 
the purpose of illustration and not limitation, the internal diameter of 
the guiding introducer may vary from about 6 to about 10 "French" (1 
French equals 1/3 of a millimeter). Such guiding introducer can accept 
dilators from about 6 to about 10 French and appropriate guidewires. 
Obviously, if larger or smaller dilators or catheters are used in 
conjunction with the guiding introducers of the instant invention, 
modifications in size or shape can be made to the instant guiding 
introducers. 
Variations in size and shape of the guiding introducers are also intended 
to encompass pediatric uses, although the preferred uses are for adult 
human hearts. It is well recognized that pediatric uses may require 
reductions in size of the various sections of the guiding introducer, in 
particular the first section, but without any significant modification to 
the shape or curves of the guiding introducer. 
In addition, variations in size or shape of the guiding introducers are 
also intended to encompass the specialized situations that sometimes occur 
in patients with enlarged and rotated hearts. 
The second embodiment of the guiding introducer (FIGS. 3A, 3B and 3C) is 
designed for use in the treatment of left ventricular tachycardia located 
on the anterior freewall of the left ventricle. In this embodiment, the 
first and second sections and the straight portion of third section are 
the same as previously discussed in the description of the first 
embodiment. The difference in shape is the curved portion of the third 
section. The curve of the curved portion is similar in shape to the curved 
portion of the first embodiment. It curves away from the straight portion 
in a smooth curve with a radius of from about 0.7 to about 1.3 in. and 
preferably from about 0.9 to about 1.1 in. The arc of this curved portion 
is preferably from about 70 to about 110 degrees and more preferably from 
about 80 to about 100 degrees. The distance from the straight portion of 
the third section to the distal tip of the guiding catheter is preferably 
from about 0.8 to about 1.2 in. and more preferably from about 0.9 to 
about 1.1 in. ending in the distal tip. In this second embodiment, the 
curved portion of the third section curves out of the plane formed by the 
first and second sections clockwise from about 45 degrees to about 135 
degrees when viewed from the proximal end of the first section. See FIG. 
3C. 
The third embodiment of the guiding introducer (FIGS. 4A and 4B) is 
designed for use in the treatment of left ventricular tachycardia located 
on the lateral freewall of the left ventricle. See FIG. 1B. The shape of 
this guiding catheter varies from the first and second embodiment in the 
extent of the curvature of the second section and also the shape of the 
curved portion of the third section. The first section of this third 
embodiment is generally the same as disclosed in the first and second 
embodiments. As previously discussed, the extent of the curvature of the 
second section of this third embodiment is less than the curvature of the 
second section of the first and second embodiments. (Compare FIG. 4A with 
FIGS. 2A and A.) The extent of the curvature of this second section is 
preferably from about 160 to about 200 degrees and more preferably from 
about 170 to about 190 degrees of arc. The second section is generally 
coplanar with the first section. See FIG. 4B. 
The third section of the third embodiment has a straight portion and a 
curved portion. The straight portion of the third section of the third 
embodiment has been previously discussed and is generally coplanar with 
the first and second sections. The curved portion of the third section 
begins at the distal end of the straight portion of the third section. The 
curved portion of the third section is similar to the curved portion of 
the first embodiment except it is curved in a simple curve in the opposite 
direction of the first embodiment, to the right (as shown in FIG. 4A). The 
extent of the curve is similar to the extent of curvature of the curved 
portions of the first and second embodiments. (Compare FIGS. 2A and 3C 
with FIG. 4A.) The arc of the curve is from about 70 to about 110 degrees 
and preferably from about 80 to about 100 degrees. The radius of this 
curve is from about 0.7 in. to about 1.3 in. and preferably from about 0.9 
in. to about 1.1 in. As with the curved portion of the first embodiment, 
the curved portion of the third section can curve out of the plane formed 
by the first and second section from about 45 degrees clockwise to about 
45 degrees counterclockwise when viewed from the proximal end of the first 
section. 
The fourth embodiment of the guiding introducer (FIGS. 5A, 5B and 5C) is 
designed for use in the treatment of left ventricular tachycardia located 
on the posterior freewall of the left ventricle. The first, second and 
straight portion of the third section are the same as disclosed in the 
third embodiment and are substantially coplanar. (Compare FIGS. 4A and 5A) 
The curved portion of the third section is comprised of a simple curved 
section, curving to the left as shown on FIG. 5B or upward as shown in 
FIG. 5C. The arc of the curve is from about 70 to about 110 degrees and 
preferably 80 to about 100 degrees. The radius of this curve is from about 
0.7 in. to about 1.3 in. and preferably from about 0.9 in. to about 1.1 
in. As with the curved portion of the first, second and third embodiments, 
the curved portion of the third section of the fourth embodiment can be 
rotated out of the plane formed by the first and second sections from 
about 45 degrees to about 135 degrees counterclockwise when viewed from 
the proximal end of the first section. See FIG. 5C. 
As a result of these four embodiments, four separate guiding introducers 
are disclosed which are similar in shape except for the angle of the curve 
of the second section, the length of the straight portion of the third 
section, the direction of curve of the curved portion and the extent of 
rotation of this curved portion of the third section out of the plane 
formed by the first and second sections. By each of the four guiding 
introducers being about to rotate at least about 45 degrees clockwise and 
counterclockwise from the fixed position shown in the respective Figures 
(for example FIGS. 3C and 5C), a full 360 degrees of rotation is possible 
about the plane formed by the first and second sections with these guiding 
introducers thereby assisting in ablation procedures on all walls of the 
left ventricle from septum to anterior to lateral to posterior freewall. 
In operation, a modified Seldinger technique is normally used for the 
insertion of the catheter into the femoral artery. Using this procedure, a 
small skin incision is made at the appropriate location to facilitate the 
catheter or dilator passage. The subcutaneous tissue is then dissected, 
followed by a puncture of the vessel with an appropriate needle with 
stylet positioned at a relatively shallow angle. The needle is then 
partially withdrawn and reinserted at a slightly different angle into the 
vessel, making sure that the needle remains within the vessel. A soft 
flexible tip of an appropriately 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 artery up to the aorta, across the aortic valve into the left 
ventricle. With the guidewire in place, a dilator is then placed over the 
guidewire with the guiding introducer placed over the dilator. The dilator 
and guiding introducer generally form an assembly to be advanced together 
along the guidewire into the left ventricle. After insertion of the 
assembly, the guidewire and dilator are then withdrawn. The catheter to be 
used for treatment of left ventricular tachycardia is advanced through the 
lumen of the guiding introducer and is placed at an appropriate location 
in the left ventricle. The choice of the guiding introducer to be used 
will depend on the location of the tachycardia in the left ventricle as 
has previously been discussed. 
By choice of the desired predetermined shape of the guiding introducer in 
conjunction with fluoroscopic viewing, the distal portion of the guiding 
introducer can be manipulated to direct the distal end of an ablation 
and/or mapping catheter placed within the lumen of the guiding introducer, 
to a specific internal surface within the left ventricle. In addition, by 
providing sufficient rigidity and support as the guiding introducer is 
held in place by the anatomical structure of the heart as well as the 
vasculature, the distal end of the guiding introducer can be maintained in 
that fixed location or surface position of the endocardial structure to 
permit the appropriate procedures to be performed. If sensing procedures 
are involved, the guiding introducer is 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 a sensing electrophysiology catheter 
placed within the guiding introducer. Further, as the guiding introducer 
permits precise location of catheters, the ablation electrode of an 
ablation catheter may be placed at a precise location for destruction by 
the use of energy, for example, thermal, laser, direct current (low energy 
direct current, high energy direct current or fulgutronization 
procedures), possibly along with reduced temperature or iced procedures. 
This precise location of the ablation catheter electrode 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 constantly moving 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 
introducer is used. The precise placement of the ablation catheter within 
the left ventricle is particularly important because of the difficulties 
associated with the ablation of left ventricular tachycardia. Treatment of 
tachycardia in the left ventricle is significantly more difficult because 
of the thickness of the wall of the left ventricle than, for example, the 
treatment of Wolff-Parkinson-White Syndrome where the ablation procedures 
occur in a portion of the heart where the myocardial tissue is 
significantly thinner. It has been determined that the time of ablation 
must be substantially lengthened to achieve not only two dimensional 
ablation but also the three dimensional ablation that is necessary for the 
ablation of left ventricular tissue. Thus, not only is the precise 
location of the ablation electrode necessary, but continuous contact of 
the ablation electrode with the left ventricle is also necessary. Larger 
or longer electrodes of the ablation catheter may be necessary to achieve 
efficient and effective ablation. Further, other types of energy than 
radio frequency may be necessary for the extensive ablation necessary for 
the elimination of the location within the ventricle. 
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.