Continuous-wave Doppler for the noninvasive evaluation of aortic blood velocity and rate of change of velocity: evaluation in dogs.

A new continuous-wave Doppler device is described, which has the capability of measuring peak aortic blood velocity and acceleration noninvasively in the ascending aorta of patients. To test the accuracy of the device, blood velocity and acceleration in the ascending aorta were compared with measurements obtained using an electromagnetic flowmeter in 16 open-chest anesthetized dogs. The Doppler probe was hand held directly on the aorta. Aortic flow was measured with a cuff electromagnetic flow transducer placed at the root of the aorta. Isoproterenol and propranolol, sometimes in combination with lidocaine, were administered intravenously to augment or reduce left ventricular contractile performance. Values of peak velocity, measured with the Doppler, corresponded closely to values measured with the electromagnetic flowmeter (r = 0.95). Values of peak acceleration also corresponded closely with the electromagnetic flow measurements (r = 0.96). The results indicate that valid measurements of blood acceleration in the ascending aorta, as well as blood velocity, can be obtained with continuous-wave Doppler.