Reversible Pulmonary Hypertension in an Infant Treated with Diazoxide

Background: Diazoxide is the main therapeutic agent for congenital hyperinsulinism. The drug is generally well tolerated; however, in this report severe adverse effects including heart failure (HF) and pulmonary hypertension (PH) in an infant are reported.Case report: A sixteen-day male infant with persistent hypoglycemia and with diagnosis of congenital hyperinsulinism underwent near total pancreatectomy. Despite surgery, hypoglycemia persisted, and thus oral dizoxide 5 mg/kg/dose three times per day was administered. At four months of age, the patient was again admitted to the hospital because of respiratory distress and poor feeding from a week earlier. On physical examination, he was tachypneic and mild intercostal retraction was present. Tachycardia existed without definitive murmur. Moderate hepatomegaly was detected. Chest X-ray revealed cardiomegaly. Echocardiography showed right atrial and ventricular dilatation, and pulmonary pressure of 70 mmHg. In the next day, respiratory failure developed and so the patient was intubated and mechanically ventilated. Diazoxide was discontinued and 10% dextrose water (DW) was initiated. Four days later, the patient was extubated. Blood glucose remained in normal limit. Gradually the concentration of DW was decreased. The patient was discharged and followed up without any medication. Echocardiogram in one month later showed normal heart dimension and reduction of pulmonary pressure to 20 mmHg, and resolution of right atrial and ventricular enlargement.Discussion: Diazoxide reduces peripheral vascular resistance and blood pressure as the result of direct vasodilatory effect on smooth muscles in peripheral arterioles. It causes sodium and water retention and decrease of urinary output which can result in expansion of plasma and extracellular fluid volume, and consequently edema and congestive cardiac failure.Conclusion: Diazoxide therapy for infants with congenital hyperinsulinism is associated with the threat of PH and HF. Periodic echocardiography may be helpful for the infants under long term diazoxide therapy.