Blood pressure estimation by processing of echocardiography signals

Noninvasive pressure estimation within the heart cavities or coronary arteries is essential for providing information on blood perfusion and on the viability of the organ. Some ultrasound contrast agents (UCAs) may be suited for pressure measurements because pressure changes affect the reflectivity of the microbubbles. Simulations and in-vitro experiments were conducted with a UCA (Optison) using 2.0-MHz ultrasound pulses. Preliminary results indicate that, over the pressure range of 0-210 mmHg, the rate (slope) of decline (as a function of time) of the amplitudes of the first and second harmonics and of the sub-harmonic may be suitable parameters for estimating hydrostatic pressure changes. The difference between the amplitude of the first harmonic and that of the sub-harmonic stays almost constant throughout a specific time window, thus demonstrating a good and stable correlation with the hydrostatic pressure.