arrhythmia

Arrhythmia is an abnormal heart rhythm caused by problems with the heart's electrical impulses. It can involve too fast (tachycardia), too slow (bradycardia), or irregular rhythms, and ranges from benign to life-threatening. The heart's rate and rhythm are normally controlled by specialized pacemaker cells and the conduction system. Disruptions may arise from structural heart disease, electrolyte imbalances, hormonal disorders, medications, or inherited channelopathies, and may occur at rest or with activity.

Common forms include atrial fibrillation, atrial flutter, and other supraventricular tachycardias; ventricular tachycardia and ventricular fibrillation; and bradyarrhythmias such as sinus node dysfunction or atrioventricular block. Atrial fibrillation is the most frequent sustained arrhythmia in adults and increases stroke risk.

Symptoms vary and may include palpitations, lightheadedness, dizziness, fainting, chest discomfort, or shortness of breath. Some arrhythmias cause no symptoms and are found incidentally.

Diagnosis relies on electrocardiography. Additional tests may include ambulatory ECG monitoring, echocardiography, exercise testing, and laboratory studies to identify reversible causes.

Treatment depends on the arrhythmia and its effects. Goals include relieving symptoms, maintaining a safe heart rate, preventing strokes (notably in atrial fibrillation where anticoagulation may be indicated), and avoiding sudden death. Treatments include lifestyle modification, medications (beta blockers, calcium channel blockers, antiarrhythmic drugs), electrical cardioversion, catheter ablation, and devices such as pacemakers or implantable cardioverter-defibrillators (ICDs). Acute management of unstable rhythms requires resuscitation with CPR and defibrillation when appropriate.

Prognosis varies with underlying disease and rhythm type. Regular follow-up and risk factor management are essential to reduce complications.