Afterdepolarization

Afterdepolarization is a term used in cardiology to describe a disturbance in the cardiac rhythm of the heart. This phenomenon can occur either immediately after a heartbeat, known as early afterdepolarization, or it can occur a little later, known as delayed afterdepolarization. Both types of afterdepolarization can lead to arrhythmia, a condition where the heart beats irregularly, either too fast or too slow.

Early Afterdepolarization

Early afterdepolarization (EAD) is a type of afterdepolarization that occurs during phases 2 and 3 of the cardiac action potential. This is the period of repolarization, where the cells of the heart are recovering from the previous heartbeat and preparing for the next one. EADs are often associated with Long QT syndrome, a disorder of the heart's electrical activity that can cause sudden, uncontrollable, and irregular heartbeats.

Delayed Afterdepolarization

Delayed afterdepolarization (DAD) occurs after the completion of phase 3 of the cardiac action potential. This is the period of time when the cells of the heart are at rest, between heartbeats. DADs are often associated with conditions such as Digitalis toxicity and Catecholaminergic polymorphic ventricular tachycardia (CPVT), both of which can lead to life-threatening arrhythmias.

Causes and Risk Factors

The exact cause of afterdepolarizations is not fully understood, but they are thought to be related to changes in the levels of certain ions, particularly calcium, within the cells of the heart. Risk factors for afterdepolarizations include certain genetic conditions, medications, and lifestyle factors such as stress and excessive alcohol consumption.

Treatment

Treatment for afterdepolarizations and the arrhythmias they cause typically involves managing the underlying condition that is causing the afterdepolarizations. This may involve medication, lifestyle changes, or in some cases, surgery.

See Also

• Cardiac action potential
• Arrhythmia
• Long QT syndrome
• Digitalis toxicity
• Catecholaminergic polymorphic ventricular tachycardia

Afterdepolarization Resources
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