Q. What is an electrophysiological (EP) study of the heart?
A. The normal heartbeat is controlled by electrical signals. The heart has its own built-in “pacemaker” to control the heart rate. This is a group of cells in the right atrium called the sinus node. These cells automatically fire at about 60 beats per minute. This rate is slowed by nerve signals during eating and sleeping and speeds up during activity up to the maximum heart rate (usually calculated as 220 beats per minute minus your age). The electrical signal from the sinus node spreads through the right and left atrium to make the chambers contract and then passes through special muscle fibers called the AV (atrioventricular) node to activate the ventricular chambers.
In a normal heart, the atrial and ventricular chambers beat at the appropriate rate and also beat in sync with each other: atrial contraction, then ventricular contraction.
Abnormal electrical signals can cause slow or fast heart rhythms that may lead to symptoms such as dizziness, blackouts or palpitations (the sensation of abnormal heartbeats). EP studies are performed in some patients, more frequently for patients with fast heartbeats, to diagnose and treat abnormal electrical signals.
The EP study is a low-risk heart procedure performed with sedation and usually takes about an hour. Intravenous sheaths (plastic tubes) are inserted into the veins at the top of the legs and four wires (electrode catheters) are advanced through these sheaths to the heart using X-ray guidance. The wires are first used to measure the electrical signals during a normal heartbeat. Slow heart rhythms are easy to diagnose and are often treated with the implantation of a permanent pacemaker.
In patients with a history of palpitations, the wires are used to electrically stimulate the heart to cause the abnormal…