1. Field of Invention
This invention relates to a process for the mapping and treatment of atrial arrhythmia using catheters guided by a shaped guiding introducer. In addition, it relates to a preferred shape of the guiding introducer which is used with a mapping or ablation catheter for the mapping or treatment of ectopic atrial tachycardia.
2. Prior Art
Introducers and catheters have been in use for medical procedures for many years. For example, one use is to convey an electrical stimulus to a selected location within the human body. Another use is to assist in the monitoring and measuring for diagnostic tests within the human body. Thus, catheters may assist in examination, diagnosis and treatment within a human body while positioned at a specific location, which is otherwise inaccessible without more invasive procedures. In use, catheters may be inserted into a vein or artery which is near the body surface. These catheters are then guided to a 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 a precise placement of the electrodes 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 the 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, and guided 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 guided 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. Nos. 5,299,574 and 4,117,836 disclose a catheter for the selective coronary angiography of the left coronary artery and U.S. Pat. Nos. 5,295,574, 5,215,540, 5,016,640 and 4,883,058 disclose catheters for selective coronary angiography of the right coronary artery. See also U.S. Pat. No. 4,033,331. U.S. Pat. No. 5,269,326 discloses a method for transvenously accessing the pericardial space through the right atrium for particular medical procedures. 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. See also U. S. Pat. Nos. 5,231,994, 4,838,879, 5,171,232 and 5,290,229.
Atrial fibrillation is the most common sustained heart arrhythmia. It is estimated to occur in upwards of 0.4 percent of the adult population and perhaps as many as 10 percent of the population who are 60 years or older. Cox, J. L., et al., Electrophysioloqy, Pacing and Arrhythmia, "Operations for Atrial Fibrillation," Clin. Cardiol. 14, 827-834 (1991). Atrial arrhythmia may be transient or persistent. While most atrial arrhythmia occurs in individuals having other forms of underlying heart disease, some atrial arrhythmias occur independently. While atrial arrhythmias do not directly cause death as frequently as ventricular arrhythmias, they increase the risk factor for a number of other diseases such as strokes, thrombosis, atherosclerosis, systemic and cerebral embolism and cause a number of additional medical problems.
Certain patients with symptomatic or life threatening atrial arrhythmias, however, cannot be adequately treated by drugs or common medical devices, such as defibrillation, or by cardioversion. Other forms of treatment are then mandated, which may include surgery.
Another procedure used for treatment of certain types of cardiac arrhythmia within the last 10 to 15 years is catheter ablation. This procedure has been used to interrupt or modify existing conduction pathways associated with ventricular arrhythmias within the heart. The particular area for ablation depends on the type of underlying arrhythmia. One common ablation procedure is for the treatment of atrioventricular (AV) nodal reentrant tachycardia. With this problem ablation of the fast or slow AV nodal pathways has become an accepted treatment. See Singer, I., et al., "Catheter Ablation for Arrhythmias" Clinical Manual of Electrophysiology, pp. 421-431 (1993). The use of ablation catheters for ablating locations within the heart has been disclosed, for example in U.S. Pat. Nos. 4,641,649, 5,263,493, 5,231,995, 5,228,442 and 5,281,217. However, none utilize a guiding introducer to guide an ablation catheter to a particular location in the heart.
In addition, catheter ablation for the treatment of ectopic atrial tachycardia is disclosed, for example, in Walsh, Edward P. "Ablation of Ectopic Atrial Tachycardia in Children" Radio Frequency Catheter Ablation of Cardiac Arrhythmias, Chap. 23 (1994). See also Tracey, C. N. "Radio Frequency Catheter Ablation of Ectopic Atrial Tachycardia Using Paced Activation Sequence Mapping" J. Am. Coll. Cardial. Vol 21, pp. 910-917 (1993).
The sources of energy used for catheter ablation vary. Initially, high voltage, direct current (D.C.) ablation techniques were commonly used. However, because of problems associated with the use of D.C. 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. Pat. 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 being considered for ablation of heart tissue include laser, ultrasound, microwave and fulgutronization.
Ablation of a precise location within the heart requires the precise placement of the ablation catheter within the heart. Precisely positioning of the ablation catheter is especially difficult because of the physiology of the heart, particularly as the ablation procedures generally occur while the heart is beating. Commonly, the placement of the catheter is determined by a combination of electrophysiological guidance and fluoroscopy (placement of the catheter in relation to known features of the heart which are marked by radiopaque diagnostic catheters which are placed in or at known anatomical structures such as the coronary sinus, high right atrium and the right ventricle).
While these techniques have been useful for certain arrhythmias, catheter ablation is still a difficult, time consuming procedure.
Accordingly, it is an object of this invention to disclose a process for the mapping and treatment of ectopic atrial tachycardia in the right atrium by the use of an ablation catheter guided to a specific location by a shaped, guiding introducer.
It is a still further object of the invention to disclose a particular shape for a guiding introducer for use with a catheter for mapping and ablation of ectopic atrial arrhythmia within the right atrium.
It is a further object of this invention to prepare a shaped guiding introducer for use in electrophysiology procedures for the treatment of ectopic atrial tachycardia.
These and other objects can be obtained by the disclosed process for the treatment of ectopic atrial tachycardia and the design of the shaped, guiding introducer for use with that process which are disclosed by the instant invention.