Sinus tachycardia

Background

• Sinus rhythm at a rate above the upper limit of normal
  • In adults, usually >100 bpm
  • In pediatric patients it varies by age until age 8 or 9 (see pediatric vital signs)
• Usually seen as a secondary response to a primary medical condition

Causes of sinus tachycardia

• Emotional or psychiatric causes
  • Pain, anger, or anxiety
• Response to fever (about 10 bpm per degree C > 37.0)
• SIRS (from infection or other causes)
• Dehydration/hypovolemia
• Anemia
• Drug/alcohol intoxication (particularly sympathomimetic or anticholinergic drugs, but may also be seen in aspirin, theophylline, or other ingestions)
• Drug/alcohol withdrawal
• Anion gap acidosis
• Hyperthyroidism
• PE
• CHF
• Cardiac tamponade
• Myocardial contusion
• Cardiac valvular disease
• Hyper or hypoglycemia
• Myocardial infarction
• Pheochromocytoma

Clinical Features

• Tachycardia
• +/- Palpitations

Differential Diagnosis

Narrow-complex tachycardia

• Regular
  • AV Node Independent
    • Sinus tachycardia
    • Atrial tachycardia (uni-focal or multi-focal)
    • Atrial fibrillation
    • Atrial flutter
    • Idiopathic fascicular left ventricular tachycardia
  • AV Node Dependent
    • Paroxysmal supraventricular tachycardia (PSVT)
      • AV node re-entry tachycardia (AVNRT)
      • AV re-entry tachycardia (AVRT)
        • Lown-Ganong-Levine syndrome
        • Wolff–Parkinson–White syndrome
    • Junctional tachycardia
• Irregular
  • Multifocal atrial tachycardia (MAT)
  • Sinus tachycardia with frequent PACs, PJCs, PVCs
  • Atrial fibrillation
    • Atrial fibrillation with RVR
  • Atrial flutter with variable conduction
  • Digoxin Toxicity

Wide-complex tachycardia

Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)

• Regular
  • Monomorphic ventricular tachycardia
  • PSVT with aberrant conduction:
    • PSVT with bundle branch block^
    • PSVT with accessory pathway
    • Atrial flutter with bundle branch block^
  • Sinus tachycardia with bundle branch block^
  • Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
  • Metabolic
    • Hyperkalemia
    • Digoxin toxicity
    • Severe metabolic acidosis
• Irregular
  • Atrial fibrillation/atrial flutter with variable AV conduction AND bundle branch block^
  • Atrial fibrillation/atrial flutter with variable AV conduction AND accessory pathway (e.g. WPW)
  • Atrial fibrillation + hyperkalemia
  • Polymorphic ventricular tachycardia
    • Torsades de pointes
    • Nonsustained ventricular tachycardia

^Fixed or rate-related

Evaluation

Algorithm for the Evaluation of Sinus Tachycardia

Workup

• ECG
• History and physical exam
  • Look for intoxication/withdrawal, infection, dehydration, bleeding, or a psychiatric/emotional state
• Consider orthostatic vital signs
• If history and physical are unable to explain the tachycardia, limited labs and imaging studies may be indicated:
  • CBC
  • BMP
  • Utox
  • Urine pregnancy
• Consider:
  • Empiric treatment for anxiety or pain (e.g. benzodiazepine or NSAID)
  • Urinalysis
  • TSH
  • Troponin
  • CXR
  • Consider workup for PE (e.g. D-dimer or CTA)

Diagnosis

Sinus tachycardia on 12-lead ECG

• Based on ECG
  • Look for regular rate and presence of p-waves to support diagnosis of sinus tachycardia

Management

• Tailored to specific cause of sinus tachycardia:
  • Fluids for dehydration
  • Blood for hemorrhage
  • Anticoagulation/thrombolytics for PE
  • Antibiotics and fluids for sepsis
  • Benzodiazepines for alcohol withdrawal
  • Supportive care for intoxication
• If no cause identified, treat with caution
  • Beta blockers or other antiarrhythmics are not appropriate for unexplained sinus tachycardia as patient may require elevated heart rate to maintain appropriate cardiac output depending on underlying cause
  • May consider discharge with strict return precautions if no clear cause identified and no serious pathology suspected after careful work-up
    • Ensure close follow-up and strict return precautions

Disposition

• Depends on cause of tachycardia:
  • Home for pain, fever, or anxiety resolving with appropriate treatment
  • Certain withdrawal or intoxication syndromes may require ED observation or admission
  • ICU for severe sepsis
  • OR for life-threatening hemorrhage

See Also

• ECG (Main)