| abstract |
A non-invasive method and means for determining beat-by-beat assessments of a patient's cardiac performance by measuring the "pre-ejection phase" (PEP) and the "left ventricular ejection time" (LVET), the aforementioned phrases also being known as the "systolic time intervals" (STI) of the heart. The system accomplishes its function through the following method: (1) transduction of the heart sounds into an electrical phonocardiogram (PCG) signal and controlled amplification thereof; (2) extraction of initial cardiac contraction and aortic valvular events by subjecting the PCG to the general inverse-filtering technique known as "deconvolution;" (3) electronic separation of the PEP, LVET and heart pulse intervals from the deconvolved PCG with microcomputer circuitry comprising microprocessor and digital logic assemblies; (4) precise measurement and simultaneous storage of the PEP, LVET, the PEP/LVET ratio, and the heart rate with the use of electronic digital counters, timers, dividers, and buffer memories after every heart beat; and (5) finally effecting digital readout for instantly displaying the systolic time intervals, their respective ratio, and the heart rate, or for storing them for later use. |