Images in Anesthesiology: Dobutamine-induced Intraventricular Obstruction: A "Dagger" to the Anesthetized Heart?

Abstract

URING dobutamine stress echocardiography, Doppler recordings across the left ventricular outflow tract are obtained both at rest and with stress if the sonographer notes hyperdynamic function or systolic anterior motion of the anterior mitral valve leaflet. Figure A demonstrates a normal continuous-wave Doppler recording through the left ventricular outflow tract at rest. The velocity begins to rise after aortic valve opening and peaks at 1.9 m/s in early systole. In both parts of the figure, an asterisk marks the peak velocity, and an arrow identifies the point in the electrocardiogram waveform that temporally coincides with the peak velocity. The pressure gradient (∆ P) is calculated using the modified Bernoulli equation where ∆ P = 4 × (peak velocity). 2 In figure B, continuous-wave Doppler interrogation during dobutamine stress reveals significant dynamic left ventricular outflow tract obstruction with the characteristic “dagger-shaped” Doppler spectrum traced in red. This velocity peaks at 5.9 m/s in mid-to-late systole, as drag forces and the Venturi effect culminate in mitral leaflet-septal contact.