Arrhythmia
An abnormality in the rate or regularity of the heart’s electrical rhythm. It can arise from abnormal impulse formation, conduction, or both.
Cardiac conduction system: The network of specialized cardiac cells that generates and conducts electrical impulses through the heart. Its impulse pathways establish the timing and sequence that arrhythmias disrupt.
Atrial fibrillation: A common arrhythmia marked by disorganized electrical activity in the atria and an irregular, often rapid heartbeat. It is a frequent sustained arrhythmia and raises the risk of blood clots and stroke.
Holter monitor: A portable electrocardiogram that continuously records heart activity, usually for one or two days. It can capture intermittent arrhythmias that a brief clinic recording misses.
Palpitations: The subjective sensation of an abnormal, forceful, rapid, or irregular heartbeat. They are a common symptom that may accompany an arrhythmia, though they do not establish its presence.
Sinus rhythm: The normal heart rhythm initiated by electrical impulses from the sinoatrial node. It provides the baseline for distinguishing abnormal impulse origins and timing.
Electrocardiography: The recording and interpretation of electrical activity measured at the body's surface. Its waveforms reveal abnormal heart rates, rhythms, and conduction patterns.
Ventricular tachycardia: A rapid rhythm arising from the heart's ventricles. It can sharply reduce effective pumping and progress to cardiac arrest.
Electrophysiology study: An invasive test that maps electrical activity inside the heart using catheter electrodes. It can identify the source and pathways of certain arrhythmias.
Syncope: A brief loss of consciousness caused by temporary insufficient blood flow to the brain. A rhythm that suddenly limits cardiac output can cause fainting.
Sinus tachycardia: A faster-than-normal heart rhythm that still originates in the sinoatrial node. It is a fast rhythm but may be a normal response to exercise, fever, or stress.