Case Report: BC is a 4 kg term LGA female born to an insulin dependent diabetic. Family history was negative for hepatic, muscle, and cardiac disease. Apgar scores were 0, 4, 6 at 1, 5, and 10 min due to a prolonged delivery. No murmur or hepatosplenomegaly were found. Severe hypoxemia and acidosis resulted in transport and emergency cannulation for VA ECMO. An echocardiogram (ECHO) on ECMO revealed HOCM, asymmetric septal hypertrophy (ASH), RV hypertension, a PDA, and no left ventricular outflow tract (LVOT) gradient. By ECMO hour 144, the infant weaned to idle flow, and was on furosemide with restricted fluids. Unable to wean off bypass due to hypotension and hypoxia, an ECHO showed HOCM, ASH (septum 10 mm, LV posterior wall 4.4 mm), systolic anterior motion of the mitral valve, LV cavity obliteration (10 mm at end diastole), midcavity obstruction (2.4 mm) with maximum Doppler systolic gradient of 80 mm Hg and LV hyperdynamic systolic function (shortening fraction 69%). Alternative therapy was initiated withβ blockade (esmolol) monitored by ECHO, and increased fluid administration. Furosemide was discontinued. Over 24 hrs oxygenation improved. ECHO showed increased LV end diastolic measurement and less LV midcavity obstruction (peak systolic gradient decreased from 80 to 30 mm Hg). ECMO was successfully discontinued.

Discussion: IDM's with obstructive HOCM on ECMO may requireβ blockade and excess fluids to relieve LVOT obstruction, permitting weaning off ECMO. Conventional therapy with inotropes, afterload reducers, fluid restriction and diuretics should be avoided.