Abstract
In twelve patients, the relationship between changes in pulse wave velocity and the pressure gradient of the aortic-to-radial arteries after cardiopulmonary bypass (CPB) was investigated. The changes in arterial pressure through aorta-to-radial arteries were measured using a guide wire of 0.37mm diameter tipped with a miniature transducer before and after CPB. The changes in the pulse wave velocity were calculated by measuring the propagation time between the QRS complex of the ECG and the corresponding arterial pressure wave. Thereafter, they were converted into volume distensibilities using the Bramwell-Hill equation. We found that in the patients showing a pressure gradient after CPB (7 out of 12), intravascular pressure and pulse wave velocity decreased gradually from aorta to radial arteries, and that corresponding volume distensibility increased gradually. Measurements by pulsed Doppler ultrasound showed no significant changes in artery diameter or wall thickness after CPB. These results suggest that the aortic-to-radial artery pressure gradient is attributed to gradual changes in volume distensibility, that is, to arterial elasticity gradient. It might be possible that the decreased elasticity prevents the intravascular pressure rise. The cause of elasticity gradient is a subject for future study.
