Fascicular tachycardia in infancy and the use of verapamil: a case series and literature review

Abstract

Objective: Guidelines state that verapamil is contraindicated in infants. This is based on reports of cardiovascular collapse and even death after rapid intravenous administration of verapamil in infants with supraventricular tachycardia (SVT). We wish to challenge this contraindication for the specific indication of verapamil sensitive ventricular tachycardia (VSVT) in infants.

Design: Retrospective case series and critical literature review.

Setting: Hospitals within New Zealand.

Patients: We present a series of three infants/young children with VSVT or 'fascicular VT'.

Results: Three children aged between 8 days and 2 years presented with tachycardia 200-220 beats per minute with right bundle brunch block and superior axis. Adenosine failed to cardiovert and specialist review diagnosed VSVT. There were no features of cardiovascular shock. Verapamil was given as a slow infusion over 10-30 min (rather than as a push) and each successfully cardioverted without incident. Critical review of the literature reveals that cardiovascular collapses were associated with a rapid intravenous push in cardiovascularly compromised infants and/or infants given other long-acting antiarrhythmics prior to verapamil.

Conclusions: Verapamil is specifically indicated for the treatment of fascicular VT, and for this indication should be used in infancy, as well as in older children, as first-line treatment or after failure of adenosine raises suspicion of the diagnosis. We outline how to distinguish this tachycardia from SVT and propose a strategy for the safe intravenous slow infusion of verapamil in children, noting that extreme caution is necessary with pre-existing ventricular dysfunction.

Keywords: ECG; arrhythmia; calcium channel blocker; contraindication; infant; safety; ventricular tachycardia.

Figure 1

(A) ECG of patient 1 on arrival. This shows a tachycardia at about 220 bpm with a superior axis and right bundle branch block. There are no capture beats but ventriculoatrial (VA) dissociation is visible, proving this to be ventricular tachycardia (VT) and not supraventricular tachycardia (SVT) with aberrancy. Superior axis and right bundle branch block (RBBB) make this the most common form of fascicular VT; left posterior fascicular VT. (B) ECG after conversion to sinus rhythm with intravenous verapamil. This shows a normal axis and no fascicular block. This indicates involvement of the posterior fascicle as retrograde limb in the tachycardia circuit.

Figure 2

(A) ECG on presentation in the 2-year-old child. It demonstrates tachycardia at 194 bpm with right bundle branch block (RBBB) and superior axis deviation. (B) Three-lead rhythm strip from case 3: this demonstrates ventriculoatrial (VA) dissociation and capture beats proving that this is ventricular tachycardia. Green arrows mark P waves and red arrows mark capture beats.