1. Maximum acceleration of blood has been measured in the aorta using a catheter tip velocity transducer in twelve patients undergoing diagnostic coronary angiography. Signals were obtained with the catheter tip transducer 5–6 cm above the aortic valve. From these signals, the values for peak velocity were measured, and acceleration was derived by continuous differentiation of the velocity signal.
2. The values obtained for maximum acceleration and peak velocity were inversely related to the severity of coronary artery disease as indicated by coronary angiography.
3. There was a close relationship between peak velocity, maximum acceleration and ejection fraction calculated from the left-ventricular angiogram.
4. Three patients with chest pain and no cardiac abnormality detectable by cardiac catheterization had maximum acceleration values above 1500 cm/s2 and peak velocity above 60 cm/s.
5. Four patients with definite coronary artery disease had normal intracardiac pressures and cardiac indices, but decreased ejection fractions. The values for maximum acceleration were between 750 and 1100 cm/s2 and for peak velocity between 32.0 and 58.0 cm/s.
6. Five patients had severe coronary disease with abnormal intracardiac pressures, cardiac indices and decreased ejection fraction. Values for maximum accelerations were below 850 cm/s2 and for peak velocity, below 41.0 cm/s.