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A digital minicomputer system has been developed for the on-line real-time estimation of myocardial contractility from the isovolumetric portion of the left ventricular pressure wave form. Left-ventricular pressure, its first derivative, aortic pressure, and the ECG wave forms are digitized at rates of up to 500 Hz by a special terminal located next to the patient. Data are then sent to a remotely located PDP-11 computer which calculates the myocardial pressure-velocity relationship for each heartbeat according to the Maxwell muscle model. The VCE-P curve is extrapolated to zero developed pressure using a modified hyperbolic regression algorithm to obtain Vmax estimates. Peak VCE, Vmax, peak , and time-to-peak are immediately displayed on a CRT console at the bedside. Long-term data storage for off-line analysis and statistical averaging is provided. The system is employed in the operating room for evaluation of myocardial contractility after cardiopulmonary bypass; it can be easily expanded to include multiple patients for application to the ICU/CCU environment.
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☆The work was supported in part by Veterans Administration Research Funds and National Institutes of Health Grant No. HL 14845.
☆☆Presented at the Thirty-fourth Annual Meeting of the Society of University Surgeons, New Orleans, La., 1973.
© 1973 Published by Elsevier Inc.