Electrophysiology (EP) Cardiology is a branch of medicine focusing on the heart’s electrical system and the rhythm disorders that can arise within it. Electrophysiologists (EPs) diagnose and treat conditions where the heart beats too fast, too slow, or irregularly. General cardiologists often refer patients with complex or persistent rhythm problems to an EP. The field combines diagnostic mapping techniques with therapeutic interventions to restore proper heart rhythm and improve overall heart function.
Understanding the Heart’s Electrical Wiring
The coordinated action of the heart depends on an electrical sequence traveling through specialized muscle cells. This sequence begins at the Sinoatrial (SA) Node, a cluster of cells in the upper right chamber (atrium) of the heart. The SA Node acts as the heart’s natural pacemaker, generating an electrical impulse at a regular rate, typically between 60 and 100 times per minute at rest.
The signal spreads rapidly across the upper chambers, causing the atria to contract and push blood into the lower chambers (ventricles). This electrical wave then reaches the Atrioventricular (AV) Node, situated between the atria and ventricles. The AV Node functions as a gatekeeper, momentarily delaying the electrical signal to allow the ventricles to fully fill with blood before they contract.
Once past the AV Node, the impulse travels down the Bundle of His and into the Purkinje fibers, which are conducting pathways that branch into the ventricular muscle walls. This network ensures that the ventricular chambers contract almost simultaneously, pumping blood out to the lungs and the rest of the body. The entire process of electrical discharge and muscle contraction constitutes one complete heartbeat.
Common Conditions Managed by Electrophysiologists
When the heart’s electrical wiring malfunctions, it leads to an arrhythmia. One of the most common conditions is Atrial Fibrillation (AFib), where chaotic electrical signals cause the upper chambers to quiver instead of beating effectively. This disorganized rhythm can cause symptoms like palpitations, fatigue, and shortness of breath, and significantly increases the risk of stroke due to blood pooling in the atria.
Electrophysiologists also manage various forms of Tachycardia, defined as a heart rate exceeding 100 beats per minute. Supraventricular Tachycardia (SVT) involves rapid heartbeats originating above the ventricles, often presenting as sudden episodes of a pounding heart that start and stop abruptly. Ventricular Tachycardia (VT) is a serious rapid rhythm that starts in the lower chambers and can limit the heart’s ability to pump blood, sometimes leading to sudden cardiac arrest.
Conversely, a slow heart rate, known as Bradycardia, is treated by EPs. This slow rhythm, defined as fewer than 60 beats per minute, can be caused by problems with the SA Node or a block in the conduction pathway, such as Heart Block. Symptoms associated with both fast and slow rhythms often include dizziness, lightheadedness, fatigue, and fainting (syncope).
Diagnostic and Treatment Tools
Diagnosis often begins with non-invasive monitoring using devices like a Holter monitor or event recorder to capture rhythm abnormalities. To precisely locate the source of an arrhythmia, electrophysiologists perform an Electrophysiology (EP) Study. This is an invasive diagnostic procedure where thin catheters are threaded through blood vessels, typically from the groin, and guided into the heart chambers.
Once inside the heart, catheters record the heart’s internal electrical signals and can deliver small electrical pulses to induce the irregular rhythm. This process creates a detailed electrical map of the heart, allowing the EP specialist to pinpoint the location of the faulty electrical circuit or tissue.
One of the most common therapeutic procedures is Catheter Ablation. Once the abnormal electrical pathway is mapped, the electrophysiologist uses the catheter to deliver energy, such as radiofrequency heat or cryoablation cold, to create a small scar. This scar tissue permanently blocks the abnormal electrical signals from traveling through that area, restoring a normal rhythm.
For patients with slow rhythms (bradycardia), electrophysiologists implant Pacemakers, which are small devices placed under the skin that monitor the heart rate. If the heart rate drops too low, the pacemaker delivers a low-energy electrical impulse to stimulate a contraction. For patients at risk of fast rhythms, such as Ventricular Tachycardia, an Implantable Cardioverter-Defibrillator (ICD) is used. The ICD functions like a pacemaker, but it continuously monitors for fast rhythms and can deliver a high-energy electrical shock to reset the heart to a normal rhythm.