Definition & Overview
An electrophysiology study is an invasive cardiac diagnostic test that records and evaluates the electrical activity of the heart. It is primarily used to diagnose and manage abnormal heartbeats or arrhythmia.
The natural electrical impulses of the heart are generated by the sinoatrial node. These impulses, in turn, stimulate the myocardium or heart muscles and allow the contraction of the heart chambers. The contraction needs to be efficient and consistent to allow the normal flow of blood all throughout the body. If this electrical conduction system is somehow impaired, arrhythmia occurs, a condition manifested by heartbeats that are irregular, too slow, or too fast. If left untreated or unmanaged, this may progress into serious medical conditions such as heart failure, stroke, and cardiac arrest among predisposed patients.
With the use of thin wire electrodes, the doctor conducts electrophysiology studies to make a diagnosis and decide what type of medicine can be prescribed to the patient. It can also help determine if a patient needs assistive technology such as a pacemaker or defibrillator, or needs to undergo cardiac ablation or even surgery.
Who Should Undergo and Expected Results
Electrophysiology study is performed on patients who experience symptoms of arrhythmia such as lightheadedness, shortness of breath, chest pain, and even passing out. This procedure is usually recommended if no clear diagnosis is obtained even after several alternative tests have been done. For patients who are already on medication, the test can also be done to determine drug efficacy and if there is a need for additional treatment. In this way, electrophysiology study is used as an aid in treating heart rhythm problems, not just in obtaining a definitive diagnosis.
The test is also conducted to help decide which type of implantable cardioverter/defibrillator (ICD) is suitable for patients at risk of sudden cardiac death from ventricular tachycardia or ventricular defibrillation. This device helps in the defibrillation and controlling the heartbeat pacing.
Electrophysiology studies are generally simple and safe procedures usually conducted in an electrophysiology or catheterization laboratory. This is typically an outpatient procedure and patients can go home after a few hours of rest. Most patients can even resume their daily activities after a day or two. The test usually detects specific conditions like atrial fibrillation, heart block, supraventricular or ventricular tachycardia, sick sinus syndrome, or even Wolff-Parkinson-White syndrome. Depending on the results of the test, patients may proceed to specific cardiac treatments deemed suitable for them or use a device implant like a pacemaker or ICD.
How is the Procedure Performed?
Patients remain awake throughout the whole procedure but will be given a sedative to help them relax. Electrodes are then placed in different areas of the chest and back to help monitor the procedure. The area for insertion, usually the groin or the neck, is cleaned and shaved to avoid infection. The physician will then administer local anesthesia and proceeds to puncture and insert a sheath into the artery or vein. Specialized catheters are then inserted and guided to the heart. Imaging technology like fluoroscopy is used in determining the position of catheters while inside the body throughout the procedure. Concurrently, the physician will send small electrical pulses and electrical signals from the heart that will be recorded by the catheters. This process is termed cardiac mapping and is very useful in determining the source of abnormal heartbeats. The doctor will also use a pacemaker to induce the heart to beat at different rhythms, observing abnormal behaviors under controlled conditions. In cases where the doctor determines that abnormal heartbeats are caused by an abnormal tissue, he will proceed by destroying the said tissue to correct the problem by applying radio waves (radiofrequency ablation), or using a cooling agent (cryoablation). The whole procedure usually takes less than four hours but may be longer if the ablation process is performed. The physician will then remove the catheters and sheath and close the puncture site. A bandage will be placed to provide extra pressure and prevent bleeding.
Possible Risks and Complications
As in any invasive procedure, there is always the risk of bleeding in the site where catheters are inserted. In some cases, the vein or artery may sustain some damage due to the insertion of the sheath and catheters. There is also the risk of developing an infection at the insertion site, occurrence of hematoma, as well as adverse reactions to anesthesia.
The physician will also watch out for the possible formation of blood clots that may travel into a blood vessel and may cause thrombosis or embolism since both conditions require immediate medical care.
There is also the possibility of developing severe rhythm problems following this procedure, as the heart is induced to beat in abnormal rhythms.
In rare instances, patients experience perforation of the heart. Even rarer are occurrences of conditions like fluid buildup in the space between the myocardium and pericardium, stroke, and heart attack.
Miller JM, Zipes DP. Diagnosis of cardiac arrhythmias. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 36.
Olgin JE. Approach to the patient with suspected arrhythmia. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 62.