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 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

  • Pacemaker:  These devices are indicated for patients with symptoms related to slow heart rate.  The pacemaker implantation procedure involves inserting leads (wires) into the heart, typically via the vein which runs underneath the collarbone.  The leads are then connected to a device that contains the battery and electronics for pacing, which is implanted under the skin, on the chest just below the collarbone.  The procedure is done via an incision that is about 2 inches long, under local anesthesia with conscious sedation, and the patient spends the night in the hospital following the procedure.
  • Internal Cardiac Defibrillator (ICD):  Patients with increased risk of sudden cardiac arrest (SCA), or who have survived an SCA episode, are candidates for implantation of an ICD.  The most common condition associated with an increased risk of SCA is heart failure.  The ICD's primary function is to monitor for rapid heart rhythms that could result in cardiac arrest and deliver pacing or a shock to convert the rhythm back to normal within seconds.  Technically, the ICD implantation procedure is similar to the implantation of a pacemaker, with additional testing performed to verify the function of the defibrillator. 
  • Cardiac Resynchronization Therapy (CRT):  Patients with severe heart failure and evidence of cardiac conduction system disease are candidates for CRT.  An additional pacing lead is inserted via the coronary vein to pace the left ventricle.  This results in improved cardiac function in 60-70% of eligible patients.  Because of the risk of SCA associated with severe heart failure, these patients typically receive a device that also includes an ICD.  CRT implantation is technically similar to ICD implantation, but sometimes requires considerably more time to place the lead to pace the left ventricle in an optimal position to obtain improvement in cardiac function.
  • Implantable Loop Recorder (ILR):  An ILR is a device that is implanted under the skin on the chest, which can record an EKG continuously.  No leads are placed in the circulation.  The ILR is used to help make the diagnosis of arrhythmia, or to help determine the heart rhythm in patients who suffer from unexplained syncope (passing out spells), which can be due to an underlying arrhythmia.  The procedure performed under local anesthesia with conscious sedation, and patients typically go home the same day.
  • Transvenous Lead Extraction:  In patients with existing cardiac rhythm devices, the development of infection or a device or lead malfunction will require removal of the pacing system including the leads.  Over time, the leads can develop a significant amount of scar within the vascular system and the heart, which can require complex procedures and tools to safely remove the leads intact.  We perform transvenous lead extraction, using the Spectranetics SLS II Laser Sheath System.

Please call for an appointment:

Arrhythmia Specialists El Paso

1701 Lee Trevino, Suite C

El Paso, TX  79936

(915) 593-5999

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