Alpha blocker and angiotensin-converting enzyme inhibitor in the management of severe pulmonary valve stenosis: from bench to bedside.

INTRODUCTION

Neonates with severe pulmonary valve stenosis tend to remain oxygen dependent, despite resolution of the transpulmonary gradient. Alpha 2 blockers – phentolamine – and angiotensin-converting enzyme inhibitors – captopril – were reported to improve oxygen saturation.

OBJECTIVE

To describe the role of phentolamine and captopril in the treatment of these patients.

METHODS

In a retrospective cohort study, 28 neonates with severe pulmonary valve stenosis underwent balloon valvuloplasty. Among them, 20 remained oxygen or prostaglandin dependent after intervention, and were treated with phentolamine or captopril. Oxygen saturation was monitored before and after intervention and following treatment with these medications. Mean duration of hospitalisation was recorded.

RESULTS

Mean age and weight were 25.2 days and 3.1 kg, respectively. Before balloon dilation, 18/20 (90%) neonates were on prostaglandin, whereas after the procedure only 6/18 patients required it. All 20 patients required oxygen after the procedure, and nine patients (45%) were started on phentolamine. Among them, one patient with severe infundibular stenosis did not respond favourably, and 11 patients (55%) were started on captopril. After starting phentolamine or captopril treatment, prostaglandin could be discontinued after a mean time of 15.86 hours. Within <2 days, there was an increase in mean oxygen saturation from 76.6 to 93.0%.

CONCLUSION

Phentolamine and captopril seem to have therapeutic roles in neonates with severe pulmonary valve stenosis who remain oxygen dependent after balloon dilation. Both drugs led to vasodilation of the pulmonary and systemic vascularisation and facilitated inflow to the right ventricle. Right-to-left shunt across a patent foramen ovale or atrial septal defect decreased and saturation improved, leading to a significant reduction in the length of hospitalisation.