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  • Title: [Physiology of cardiac performance].
    Author: Namba T, Takaki M, Araki J, Ishioka K, Akashi T, Matsushita T, Fujii W, Suga H.
    Journal: Rinsho Byori; 1993 Apr; 41(4):415-20. PubMed ID: 8350502.
    Abstract:
    We previously proposed i) Emax (end-systolic maximum elastance of the ventricle) as an index of contractility independent of preload and afterload and ii) PVA (systolic pressure-volume area of the ventricle) as a measure of the total mechanical energy generated by the ventricular contraction. Emax is defined as the slope of the end-systolic pressure-volume relation, which is relatively linear within the normal working range of the left ventricle. A working pressure-volume point starts from the end-diastolic pressure-volume curve, comes close to or slightly exceeds the end-systolic pressure-volume line, and returns to the end-diastolic curve. Thus, the end-diastolic and end-systolic pressure-volume curves envelop a family of pressure-volume trajectories of variously loaded contractions in a stable contractility. Emax increases with enhanced contractility and decreases with depressed contractility. PVA is an area between the end-diastolic and end-systolic pressure-volume curves on the origin side of the systolic pressure-volume trajectory. PVA linearly correlates with myocardial oxygen consumption regardless of ventricular loading conditions in a given Emax and this load-independent oxygen consumption-PVA relation is elevated with an enhanced Emax. Consequently, Emax and PVA have proved to be key measures and concepts in the physiology of cardiac performance.
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