Sinus tachycardia
Sinus tachycardia is a sinus rhythm above 100 per minute, almost always a physiologic response to an underlying stressor such as fever, hypovolemia, pain, anemia, hypoxia, or hyperthyroidism. Management targets the cause rather than the rate, and rate-slowing drugs are usually harmful when tachycardia is compensatory.
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What this article covers
- Overview
Definition: sinus tachycardia is a sinus rhythm at a rate above 100 per minute with a normal P wave preceding every QRS, arising from the sinoatrial node.
- Epidemiology
Extremely common, the normal response to exertion, stress, and illness.
- Risk factors
Physiologic demand: exercise, pain, anxiety, and fever.
- Pathophysiology
Autonomic drive: increased sympathetic tone and reduced vagal tone accelerate sinoatrial firing.
- Clinical features
Palpitations and awareness of a fast heartbeat.
- Differential diagnosis
Atrial flutter with 2:1 block: regular at about 150, with sawtooth waves (supraventricular tachycardia).
- Diagnosis
Establish with an ECG showing a sinus rhythm above 100 with normal P-wave morphology, then identify the cause: the diagnostic basis is a 12-lead ECG confirming a sinus P wave before every QRS at a…
- Management
First-line, treat the underlying cause: give an isotonic crystalloid bolus of 500 to 1000 mL IV for hypovolemia (or blood for hemorrhage), antipyretics and antibiotics for infection, oxygen for…
- Complications
Usually none from the rhythm itself, which resolves with the cause.
- Prognosis
Excellent, with resolution once the underlying cause is corrected.
- Prevention
Maintain hydration and treat anemia to avoid compensatory tachycardia.
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Related articles
- Inappropriate sinus tachycardia
Inappropriate sinus tachycardia is a persistently elevated resting sinus rate, or an exaggerated rate response to minimal exertion, without an identifiable secondary cause. It is a diagnosis of exclusion in young women, and treatment centers on beta-blockade or ivabradine after ruling out reversible drivers.
- Sinus bradycardia
Sinus bradycardia is a sinus rhythm below 60 per minute with normal P-wave morphology and a normal PR interval. It is most often a benign physiologic finding in fit or sleeping people, and treatment is needed only when it is symptomatic or reflects a reversible cause such as drugs, ischemia, or hypothyroidism.
- Supraventricular tachycardia
Supraventricular tachycardia is any tachyarrhythmia arising at or above the AV node, usually a regular narrow-complex tachycardia. Acute management of a stable regular narrow-complex SVT is vagal maneuvers then adenosine; unstable patients receive synchronized cardioversion, and definitive therapy is catheter ablation.
- Paroxysmal supraventricular tachycardia
Paroxysmal supraventricular tachycardia is a sudden-onset, regular narrow-complex tachycardia from a reentrant circuit involving the AV node (AVNRT) or an accessory pathway (AVRT), presenting with abrupt palpitations. Acute treatment is vagal maneuvers then adenosine, unstable patients receive synchronized cardioversion, and catheter ablation is a curative long-term option.
- Atrial fibrillation
Atrial fibrillation is a supraventricular tachyarrhythmia with disorganized atrial activation and an irregularly irregular ventricular response, the most common sustained arrhythmia and a major cause of stroke. Diagnosis is by ECG showing no discrete P waves with irregular RR intervals, and management addresses rate or rhythm control, stroke prevention by CHA2DS2-VASc-guided anticoagulation, and the underlying cause.
- Multifocal atrial tachycardia
Multifocal atrial tachycardia is an irregular atrial tachyarrhythmia defined by at least three distinct P-wave morphologies and varying PR intervals, arising from multiple atrial foci and strongly associated with severe pulmonary disease such as COPD exacerbation. Diagnosis is by ECG, and treatment centers on correcting the underlying illness, with a non-dihydropyridine calcium channel blocker for rate control.