UNDERSTANDING CONTINUOUS-WAVE DOPPLER SIGNAL INTENSITY AS A MEASURE OF REGURGITANT SEVERITY

Continuous-wave Doppler signal intensity is commonly expected to refle ct the severity of mitral regurgitation. Physical principles predict t hat alignment of the imaging beam, flow velocity, and turbulence can a lso be important or even dominant determinants of continuous-wave Dopp ler signal intensity. The reliability of tracking regurgitant severity with continuous-wave Doppler signal intensity was assessed in vitro w ith varying volume, velocity, turbulence, and beam alignment. The cond itions wherein continuous-wave Doppler signal intensity increased with regurgitant volume were specific but poorly predictable combinations of orifice size, flow volume, and perfect beam alignment. Under other conditions flow velocity and turbulence effects dominated, and continu ous-wave Doppler signal intensity did not reflect changing regurgitant volume. Continuous-wave Doppler signal intensity-based impressions of regurgitant severity may be unreliable and even misleading under some circumstances.