Arginine vasopressin (AVP) is the primary regulator of free water retention through its interactions with the AVP type 2 receptor (V2). As opposed to the natriuresis and diuresis that occur with loop and thiazide diuretics, conivaptan is an AVP V1A/V2 receptor antagonist, which enhances free water excretion while minimizing sodium loss. We report our preliminary experience with conivaptan to promote diuresis in infants with functional or structural cardiac disease.
A retrospective cohort study was conducted of infants who had received conivaptan from August 2007 to January 2008. A loading dose of conivaptan (0.3-0.6 mg/kg) was followed by a continuous infusion of 0.01-0.02 mg/kg/hr for 24 hours. Sodium, potassium, chloride, blood urea nitrogen (BUN), creatinine, bicarbonate, and urine output were measured prior to the start of conivaptan and at 24 hours after initiation of the infusion.
Conivaptan was administered intravenously on 6 occasions to 5 patients with hypervolemic hyponatremia. Patients ranged in age from 8 to179 days, and body weight ranged from 3 to 4.12 kg. Mean sodium concentration increased from 130.17 ± 1.94 mEq/L to 133.67 ± 3.88 mEq/L (p=0.048), and median urine output increased from 4.15 to 5.05 mL/kg/hr (p=0.286). No significant changes were noted in serum potassium, bicarbonate, creatinine, or BUN. No adverse effects were noted during conivaptan infusion.
Intravenous conivaptan is effective for increasing serum sodium levels and may be a potential adjuvant to enhance diuresis in children with cardiac disease. Given the potential benefits of conivaptan compared to diuretic therapy, with all their potential complications, prospective trials are warranted.