tachycardiabradycardia

Tachycardiabradycardia is a condition characterized by alternating episodes of tachyarrhythmia and bradyarrhythmia, resulting in a fluctuating heart rate. It is most commonly described in the context of sick sinus syndrome and conduction system disease, and is often referred to as tachy-brady syndrome.

The condition arises from dysfunction of the sinus node with episodes of rapid atrial activity (such as atrial fibrillation or atrial flutter) followed by pauses or slow ventricular rates. Contributing factors include structural heart disease, ischemia, electrolyte disturbances, thyroid disorders, and medications that slow conduction, such as beta-blockers or non-dihydropyridine calcium channel blockers.

Patients may experience palpitations during tachycardic spells and dizziness, syncope, or fatigue during bradycardic spells. The pattern is often intermittent, with symptoms clustering during episodes of rapid heart rate and pauses.

Diagnosis relies on ECG documentation of alternating fast and slow rhythms. Ambulatory monitors (Holter, event records) and telemetry track rhythm changes over time, while echocardiography assesses structural heart disease. An electrophysiology study may be used to delineate the mechanism.

Management focuses on treating reversible causes and choosing pacing strategies for symptom relief. Pacemaker therapy, especially dual-chamber pacing, is commonly indicated for symptomatic bradycardia or significant pauses. Treatment of the tachyarrhythmia may involve rate and rhythm control strategies, and ablation in selected cases. The prognosis depends on the underlying disease.