Evaluation of human coronary blood flow with an 80 channel 20 MHz pulsed Doppler velocimeter and zero-cross and Fourier transform methods during cardiac surgery.

To evaluate local blood flow velocities accurately at many sampling points in small vessels, especially in human coronary arteries, we have developed an 80 channel 20 MHz pulsed Doppler velocimeter. Doppler signals from 80 channels are detected by a zero-cross method and a signal from an optional channel is analyzed by a fast-Fourier transform method, both in real time. Basic experiments using a model and animals have demonstrated the accuracy and utility of our method of measurement of blood flow velocity for both nondisturbed and disturbed flow. Velocity waveforms in a native coronary artery beyond a vein bypass graft insertion were measured during cardiac surgery. They showed a diastolic-predominant pattern with a small systolic component. During transient graft occlusion, the waveforms changed to a systolic-predominant pattern in a patient with severe stenosis and to a to-and-fro pattern in a patient with total occlusion. In a patient with severe aortic regurgitation, the coronary arterial velocity waveforms exhibited a systolic-predominant pattern with a broad velocity spectrum. After aortic valve replacement, however, a diastolic-predominant pattern with a narrow spectrum was observed.