High-fidelity, infinite time constant calibrated pressure apexcardiogram and its correlation with high-fidelity left ventricular pressure.

A technique of recording the pressure apexcardiogram by means of a high-fidelity piezoresistive transducer has been developed in our laboratory. It permits the quantification of pressure with which the transducer is applied to the chest wall as well as the pressure changes during a cardiac cycle. In this preliminary report, apexcardiographic pressures were compared with simultaneously recorded high-fidelity left ventricular pressure in 32 patients. There were no significant differences in the timing of the left ventricular systolic upstroke and the "O" point. Peak dP/dt of the apexcardiogram occurred (10± 13 ms) significantly earlier than the intraventricular pressure recordings. Though there