Cardiac electrophysiology is a specialized area within cardiology focused on understanding and treating the heart’s electrical activity. This field investigates the electrical signals that coordinate heartbeats. When these signals malfunction, they cause irregular heart rhythms (arrhythmias), which electrophysiologists diagnose and manage. The aim is to restore a normal heart rhythm, improving the heart’s pumping efficiency through diagnostic techniques and advanced treatments.
The Heart’s Electrical System
The heart’s rhythmic contractions are orchestrated by a sophisticated electrical conduction system. This process begins in the sinoatrial (SA) node, the heart’s natural pacemaker, located in the upper right atrium. The SA node spontaneously generates electrical impulses, typically at 60 to 100 beats per minute. These impulses then spread across the atria, causing them to contract and push blood into the lower chambers.
The electrical signal next reaches the atrioventricular (AV) node, situated between the atria and ventricles. Here, the impulse is briefly delayed, allowing the atria to fully empty into the ventricles before they contract. From the AV node, the signal travels down the bundle of His and into the Purkinje fibers, which rapidly distribute the impulse throughout the ventricles. This coordinated pathway ensures the ventricles contract efficiently, pumping blood out to the body.
Conditions Addressed by Electrophysiology
Heart rhythm disorders can cause the heart to beat too fast, too slow, or with an irregular pattern. One common condition is atrial fibrillation (AFib), where the upper chambers quiver chaotically instead of contracting effectively, potentially leading to blood clots and stroke. Atrial flutter is a similar condition where the atria beat very rapidly but in a more organized pattern than AFib.
Supraventricular tachycardia (SVT) is a broad term for fast heart rhythms originating above the ventricles, including atrial fibrillation and atrial flutter. SVT episodes often cause a sudden, rapid heartbeat, typically between 150 to 220 beats per minute, which can start and stop abruptly. Ventricular tachycardia involves rapid heartbeats originating in the lower chambers, which can be life-threatening if the heart cannot pump enough blood. Ventricular fibrillation is a medical emergency where the ventricles quiver ineffectively, leading to a sudden stop in blood circulation.
Conversely, bradycardia refers to a heart rate that is unusually slow, generally fewer than 60 beats per minute. This can result from problems with the SA node or disruptions in the heart’s conduction pathways. Heart block occurs when electrical signals from the atria are slowed or completely blocked from reaching the ventricles. There are different degrees of heart block, ranging from mild first-degree to severe third-degree (complete) heart block, often requiring a pacemaker.
How Heart Rhythm Problems Are Diagnosed
Diagnosing heart rhythm problems involves specialized tests to identify the nature and origin of the electrical malfunction. The electrocardiogram (ECG or EKG) is a primary diagnostic tool that records the heart’s electrical activity through electrodes placed on the chest and limbs. An ECG can reveal how fast or slow the heart is beating and detect any rhythm irregularities. For intermittent rhythm disturbances, ambulatory monitors are used.
A Holter monitor is a portable ECG device worn for 24 to 48 hours, continuously recording the heart’s activity during daily routines. Event recorders are similar devices worn for up to 30 days, which patients activate when they experience symptoms, capturing the heart rhythm during those events. These monitors are helpful for detecting arrhythmias that do not occur during a brief office visit.
When more detailed information is needed, an electrophysiology (EP) study is performed. This invasive procedure involves inserting thin, flexible catheters into a blood vessel, typically in the groin, and guiding them into the heart. These catheters record the heart’s electrical signals from within and can also deliver small electrical impulses to trigger and map abnormal rhythms. The EP study helps pinpoint the exact location of the electrical problem, allowing for precise diagnosis and guiding treatment decisions.
Treatments for Heart Rhythm Disorders
Treatments for heart rhythm disorders vary depending on the arrhythmia type and severity. Medications, such as antiarrhythmic drugs, are often the first line of treatment, aiming to restore a normal heart rhythm or control heart rate. Other medications, like beta-blockers and calcium channel blockers, can help regulate heart rate and reduce symptoms.
Cardioversion uses controlled electrical shocks to reset the heart’s rhythm. This is typically performed under anesthesia and can quickly restore a normal rhythm, though it does not prevent future arrhythmias. Catheter ablation is a common intervention where an electrophysiologist uses heat (radiofrequency ablation) or cold (cryoablation) to create small scars in heart tissue. These scars block the abnormal electrical pathways responsible for the arrhythmia, effectively “disconnecting” faulty signals.
For individuals with slow heart rhythms or heart block, implantable devices may be necessary. Pacemakers are small devices surgically placed under the skin, sending electrical impulses to the heart muscle to maintain a normal heart rate. Implantable cardioverter-defibrillators (ICDs) continuously monitor heart rhythm and can deliver electrical energy to correct dangerously fast rhythms, such as ventricular tachycardia or fibrillation. These treatments aim to manage symptoms, reduce complication risk, and improve quality of life.
The Cardiac Electrophysiology Specialist
A cardiac electrophysiologist, or EP specialist, is a cardiologist with extensive training in the heart’s electrical system. They diagnose and treat heart rhythm disorders, performing complex diagnostic tests like electrophysiology studies to pinpoint arrhythmia sources. EP specialists also perform interventional procedures such as catheter ablation and implant devices like pacemakers and ICDs. They work closely with other cardiology professionals to guide therapy and improve patient outcomes.