Prospective Study of Adenosine on Atrioventricular Nodal Conduction in Pediatric and Young Adult Patients After Heart Transplant
Background—Supraventricular tachycardia (SVT) is common after heart transplant. Adenosine, the standard therapy for treating SVT in children and adults without transplant, is relatively contraindicated post-transplant due to a presumed risk of prolonged atrioventricular (AV) block in denervated hearts. This study tested whether adenosine caused prolonged asystole after transplant and if it was effective in blocking AV nodal conduction in these patients.
Methods—This was a single center prospective clinical study including healthy heart transplant recipients ages 6 months - 25 years presenting for routine cardiac catheterization during 2015 - 2016. After catheterization, a transvenous pacing catheter was placed and adenosine was given following a dose escalation protocol until AV block was achieved. The incidence of clinically significant asystole (≥ 12 seconds following adenosine) was quantified. The effects of patient characteristics on adenosine dose required to produce AV block and duration of effect were also measured.
Results—Eighty patients completed adenosine testing. No patient (0%; 95% CI 0-3%) required rescue ventricular pacing. AV block was observed in 77 patients (96%; 95% CI 89-99%). The median longest AV block was 1.9 seconds (IQR 1.4-3.2) with the mean duration of adenosine effect 4.3 seconds (±2.0). No patient characteristic significantly predicted adenosine dose to produce AV block or duration of effect. Results were similar across patient weight categories.
Conclusions—Adenosine induces AV block in healthy pediatric and young adult heart transplant recipients with minimal risk when using low initial doses (25mcg/kg, or 1.5mg if ≥ 60kg) and gradually escalating therapy.
Clinical Trial Registration—URL: https://clinicaltrials.gov Unique Identifier: NCT02462941
- Received February 26, 2017.
- Revision received March 30, 2017.
- Accepted April 14, 2017.