New technique for determining instantaneous myocardial force-velocity relations in the intact heart.

Abstract

A new technique is described for the instantaneous determination of myocardial force-velocity relationships. The method employs electronic differentiation of the logarithm of intraventricular pressure, which yields a continuous on-line record of (dP/dt)?(the ratio of the rate of rise of ventricular pressure ,[dP/dt] to the simultaneous ventricular pressure [P]). A further technique is described for the automatic projection of force-velocity vector loops, displaying (dP/dtJP" on the ordinate against ventricular pressure on the abscissa in a beat-to-beat fashion. An excellent correlation (r = 0.982) was demonstrated between (dP/dtJP" determined by conventional methods and that derived electronically by use of the logarithmic amplifier circuit. Experimental studies are described which document the responsiveness of (dP/dtJP" determined by the present method to interventions known to affect myocardial contractility. An increase in (dP/dt)P" was observed following infusions of CaCl2, norepinephrine, and glucagon, and a decrease following pentobarbital. Insofar as (dP/dtJP" is a valid index of myocardial contractility, the present method permits on-line, beat-to-beat evaluation of changes in ventricular function under a variety of circumstances.

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@article{Grossman1971NewTF, title={New technique for determining instantaneous myocardial force-velocity relations in the intact heart.}, author={Willian Grossman and Heddwen L. Brooks and Steven G. Meister and Herbert Sherman and Lewis Dexter}, journal={Circulation research}, year={1971}, volume={28 2}, pages={290-7} }