The wave intensity (WI) is a new hemodynamic index, which is defined as (dP/dt) (dU/dt) at any site of the circulation, where dP/dt and dU/dt are the time derivatives of blood pressure and velocity, respectively. The WI provides information about the dynamic behavior of the heart and vascular system and the interactions between them. We have developed a new real-time system, based on a conventional color Doppler system, for measuring the WI. The blood pressure waveforms were obtained

more »

... ely from the arterial diameter-change waveforms by an echo-tracking method. Using a 7.5-MHz linear array probe, we obtained the carotid arterial WI and analyzed the characteristics of the cardiac and vascular interactions. The results suggest that this system has great potential and will be very useful in clinical practice.