Narrow-complex tachycardia

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Background

  • Heart rate > 100 bpm
  • Originates above the ventricles

Clinical Features

Differential Diagnosis

Narrow-complex tachycardia

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)

^Fixed or rate-related

Evaluation

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

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

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 [1]
      • 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:
        • Paroxismal 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:
    • Rhythm conversion with:

Atrial fibrillation with RVR/flutter

Junctional tachycardia

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

External Links

References

  1. ↑ Frankel, G. et al. (2013) Rate versus rhythm control in atrial fibrillation. Canadian Family Physician 59(2), 161 - 168
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