Narrow-complex tachycardia

Background

• Heart rate > 100 bpm
• Originates above the ventricles

Clinical Features

• Heart rate > 100 bpm
• May have:
  • Palpitations
  • Syncope or pre-syncope
  • Chest pain
  • Dyspnea
  • Altered level of consciousness
  • Delayed capillary refill

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

Examples of narrow-complex tachycardias.

Workup

• ECG

Diagnosis

• Flutter vs coarse AFib: determine atrial regularity by taking big bites

Narrow-complex tachycardia comparison table

Differential	A.Rhythm	A.rate	A.morphology	Vagal/adenosine
A fib	Irregular	>350	Fibrillatory (V1)	Incr. AV block
A Flutter	Regular	>250, <350	Sawtooth (II, III, AVF)	Incr. AV block
A Tach	Regular	>100	Neg in II, III, AVF	Nothing
AVNRT (SVT)	Regular	>160	No p's	→ NSR
Junctional	Regular	>100, <150	No p's or retrograde p's	Nothing
MAT	Irregular	>100	>3 distinct p shapes	Transient slowing
Sinus tachycardia	Regular	>100 <180	Normal	Transient slowing

Narrow-Complex Tachycardia Examples

• 

  PSVT

• 

  Sinus tachycardia]]

• 

  Atrial flutter (with alternating 2:1 and 3:1 block).

• 

  Atrial flutter (with variable block)

• 

  PACs

• 

  Atrial fibrillation

• 

  Multifocal atrial tachycardia

Management

Narrow Regular Tachycardia

• Sinus tachycardia
  • Treat underlying cause
• SVT
  • Vagal maneuvers (convert up to 25%)
  • Adenosine 6mg rapid IV push if patient hemodynamically stable (unstable should proceed directly to electrical cardioversion)
    • Can follow with repeat dose of 6 mg or 12mg if initially fails
    • If adenosine fails, initiate rate control with calcium channel blocker or beta blocker or use synchronized cardioversion
      • Diltiazem 15-20mg IV, followed by infusion of 5-15mg/hr
      • Metoprolol 5mg IVP x 3 followed by 50mg PO
  • Synchronized cardioversion (50-100J)
    • Provide sedation prior to synchronized cardioversion if patient is hemodynamically stable
• Atrial flutter
  • Stable: Consider rate control to HR < 110 bpm
  • Unstable: Synchronized cardioversion; start at 50J

Narrow Irregular Tachycardia

• Multi-focal atrial tachycardia (MAT)
  • Treat underlying cause (hypokalemia, hypomagnesemia)
  • Consider diltiazem
  • Avoid beta blockers unless they are already known to be tolerated, as airway disease often co-morbid
  • If not symptomatic and rate < 110/120 bpm, may not require treatment (e.g., patient with MAT secondary to COPD)
• Sinus tachycardia with frequent PACs
  • Treat underlying cause
• A fib / A Flutter with variable conduction (see also Atrial Fibrillation with RVR)
  • Check if patient has taken usual rate-control meds
    • If missed dose, may provide dose of home medication and observe for resolution
  • Determine whether patient is better candidate for rate control or rhythm control
    • Rate control preferred with:
      • Persistent A fib
      • Less symptomatic patients
      • Age 65 or older
      • Hypertension
      • No heart failure
      • Previous failure to cardiovert
      • Patient preference
    • Rhythm control preferred with:
      • Paroxysmal or new A fib
      • More symptomatic patients
      • Age < 65 years
      • Heart failure clearly exacerbated by A fib
      • No history of rhythm control failure
      • Patient preference
  • Rate control with:
    • Diltiazem
    • Metoprolol
    • Amiodarone (good in setting of hypotension, CHF)
    • Digoxin (good in setting of CHF)
  • Rhythm conversion with:
    • Synchronized Cardioversion (120-200 J)
      • Best performed on patients with new onset A fib or patients fully therapeutically anti-coagulated for > 3 weeks
    • Procainamide per Ottawa Aggressive ED Cardioversion Protocol

Atrial fibrillation with RVR/flutter

• Rate control: Diltiazem, metoprolol, digoxin
  • Dig usually only helpful when already with a block (e.g. 2:1)
• Cardioversion: Sotalol, electric

Junctional tachycardia

• Treat underlying cause
• Consider:
  • Amiodarone
  • Beta-blocker
  • Calcium-channel blocker

Disposition

• Stable patients without serious comorbid illness who are adequately rate or rhythm controlled can be discharged home with follow-up
• Patients with acute underlying cause may require admission
• Patients who cannot achieve asymptomatic rate or rhythm control may require admission

See Also

• Tachycardia
• ACLS: Tachycardia
• V Tach vs. SVT
• SVT
• Atrial Fibrillation (RVR)