An 86-year-old female was diagnosed with severe aortic stenosis from senile calcific degeneration. The mean pressure gradient was 65 mm Hg, and severe concentric left ventricular hypertrophy was present. She was dyspneic and underwent bioprosthetic aortic valve replacement. Immediately post-operative, she is being maintained on dobutamine and epinephrine intravenously, as well as mechanical ventilation. She has remained markedly hypotensive despite the above. She is afebrile with a heart rate of 110 beats per minute, blood pressure 80/40 mm Hg, 16 respirations per minute and normal oxygen saturations on the ventilator. Physical examination reveals a III/VI systolic crescendo-decrescendo murmur at the left lower sternal border. An echocardiogram shows the valve working normally with no pericardial effusion. What is the most appropriate next course of action?
A. Reduce the dobutamine
B. Add milrinone
C. Surgical re-exploration
D. Intraaortic balloon counterpulsation
A dynamic left ventricular outflow tract obstruction can occur following aortic valve replacement from the severe left ventricular hypertrophy, or LVH, caused by the aortic stenosis, similar to that seen in hypertrophic obstructive cardiomyopathy, or HOCM. Positive inotropes such as dobutamine increase the contractile force of the heart and can worsen this phenomenon, and thus should be reduced or discontinued.