Narrow-complex tachycardia

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 p shapes	Transient slowing
Sinus	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
    • 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:
    • 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

A fib/flutter

• Rate control: Dilt, MTP, Digoxin
  • Dig usually only helpful when already with a block (e.g. 2:1)
• Cardioversion: Sotalol, electric
• See Atrial Fibrillation (RVR)

AVNRT (SVT)

• Vagal, adenosine, beta-blockers, calcium-channel blockers, dixogin, electric, procainamide, amio, sotalol

Junctional

Remove the cause, Amiodarone, beta-blockers, calcium-channel blockers

MAT

• Diltiazem
• Beta blockers often contraindicated (MAT occurs frequently with pulmonary disease)

See Also

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