Electrophysiology Study
To diagnose the precise mechanism of an arrhythmia, an electrophysiology study (EPS) is performed. We typically perform the procedure with the patient under general anesthesia. Catheters (insulated wires) that record electrical signals are advanced to the heart via veins in the groin. The arrhythmia is induced, usually by pacing the heart, sometimes with the addition of intravenous medication. Most arrhythmias are caused by a "short circuit" in the heart. During the EPS, the exact type and location of short circuit is identified. An ablation catheter is then positioned at that location.
The EP Lab at Del Sol Medical Center X-Ray Image of Catheters Placed in the Heart for EPS
Radiofrequency Catheter Ablation
With application of radiofrequency alternating current, the tip of the ablation catheter heats up and burns the small area of the heart it is touching. The tip of the catheter is typically 3.5 mm. When the ablation catheter is properly positioned at a site with the short circuit responsible for the arrhythmia, ablation selectively destroys this tissue, and eliminates the potential for recurrence.
An electroanatomic mapping system is sometimes used in the procedure. For this, the ablation catheter has a sensor that is used to visualize the tip of the catheter on a computer screen in real time. The computer can then construct a virtual model of the heart chamber by recording the locations as the catheter is moved around the heart. The movies below were made from a procedure in the left atrium. The first movie demonstrates the time sequence of building an electroanatomic map. The next movie demonstrates how the map can be manipulated to view the chamber of interest.
Creation of a Left Atrial Electroanatomic Map
Manipulation of a Left Atrial Electroanatomic Map
Timing and voltage data are also recorded during the mapping process. This data can be used to define the arrhythmia circuit. The movie below demonstrates the propagation of cardiac depolarization, indicated in red, clockwise around the right atrium, during atrial flutter. The atrium typically beats 250-300 times per minute during atrial flutter.
Atrial Flutter Propagation
For most typical supraventricular tachycardia (SVT), a single ablation procedure results in at least 95% likelihood of freedom from further arrhythmia episodes. For SVT, the procedure typically requires 3-4 hours. Patients often go home the same day, after completing 6 hours of bedrest after the catheters are removed.
Atrial Fibrillation
Atrial fibrillation is a complex heart rhythm disorder resulting in disorganized electrical activity in the left atrium. The loss of atrial mechanical function results in the risk for formation of blood clots and stroke. This rhythm is also associated with symptoms due to loss of atrial contraction and rapid heart rates, which can, in some cases, lead to the development of heart failure. Atrial fibrillation is often initiated by electrical abnormalities in and around the pulmonary veins in the left atrium. These are the veins which return oxygenated blood from the lungs back to the heart. Radiofrequency catheter ablation for atrial fibrillation is a complex procedure, with the goal of blocking electrical conduction between pulmonary veins and the rest of the left atrium. Electroanatomic mapping is used during these procedures. The left atrial movies above were made during a procedure for atrial fibrillation. Patients spend 1 night in hospital after the procedure.
Stereotaxis
Stereotaxis is an exciting technology that uses magnets to move the catheter in the heart "robotically." The Stereotaxis catheter contains magnets that align with an external magnetic field that is generated by 2 large electromagnets positioned on either side of the patient. The direction of this magnetic field is controlled by a computer, and a motor advances and retracts the catheter within the heart. This technology offers the potential for improved safety and efficacy for catheter ablation over conventional ablation catheters, which are controlled by hand by the operator from the patient's groin. The movie below demonstrates how the magnetic catheter moves in the Stereotaxis system. There are fewer than 100 Stereotaxis systems operational in the United States, one of which is located at Del Sol Medical Center in El Paso.
Cardiac Rhythm Devices
Please call for an appointment:
Arrhythmia Specialists El Paso
1701 Lee Trevino, Suite C
El Paso, TX 79936
(915) 593-5999
arrhythmiaspecialists@gmail.com