A Device for the Calculation of dP/dt/P with Internal Calibration

An analog method for the calculation of dP/dt/P is described that in-corporates a means for internal calibration. Engineering tests of this device are reported as well as tests using pressures from the left ventricle of swine (20-25 Kgm). Interventions included inflation of a balloon in the inferior vena cava (peak pressure reduced by 50 percent), occlusion of the aorta (peak pressure increased by 100 percent), and pacing (from 150 to 210 beats/min). dP/dt/P (P denotes left-ventricular pressure) calculated from the analog device agreed within the noise level when compared with the calculation based on pressure alone using an A-D converter and digital computer.