Tachyarrhythmia

Tachyarrhythmia is a broad term for any heart rhythm disturbance with a rate faster than normal. In adults, a resting heart rate above about 100 beats per minute is commonly considered tachyarrhythmic, though clinical relevance depends on symptoms and stability. Tachyarrhythmias arise from abnormal impulse formation, abnormal conduction, or both, and may originate in the atria, ventricles, or the AV node.

Classification commonly divides tachyarrhythmias into supraventricular (originating above the ventricles, such as atrial fibrillation, atrial flutter, atrial tachycardia, and AV nodal or AV reentrant tachycardias) and ventricular (originating in the ventricles, such as ventricular tachycardia and, in its chaotic form, ventricular fibrillation). QRS width helps distinguish broad from narrow complex tachyarrhythmias and guides treatment.

Causes and risk factors include structural heart disease (ischemia, cardiomyopathy, valvular disease), electrolyte disturbances, thyroid disorders, drug effects or toxicity, stimulant use, congenital channelopathies, and sleep apnea.

Clinical presentation ranges from palpitations and dizziness to chest pain or syncope, depending on rate and hemodynamic impact. Diagnosis relies on ECG documentation; ambulatory monitors, echocardiography to assess structure, and laboratory tests to identify reversible factors.

Management depends on stability and mechanism. Unstable tachyarrhythmias require urgent electrical cardioversion. For stable SVTs, vagal maneuvers followed by adenosine are common; rate control with beta-blockers or calcium channel blockers is also used. Antiarrhythmic drugs, catheter ablation for selected arrhythmias, and, in some cases, pacing or implantable cardioverter-defibrillators, form long-term strategies.

Prognosis varies with rhythm type and underlying heart disease. Some tachyarrhythmias are benign, others increase risk of stroke, heart failure, or sudden death. Prevention focuses on treating underlying conditions, appropriate anticoagulation when indicated, and definitive therapies such as ablation or device implantation as needed.