Studying the mechanics of left ventricular contraction.

Several interesting aspects of the ESPVR have been discussed in this study, including: a) A possibility to introduce, in an explicit manner, the active force of the myocardium in the formalism describing the PVR of the left ventricle. b) A possibility to express the ventriculo-arterial coupling by using the ratio Emax/eam in a way to distinguish between the normal physiological state and the mildly or severely depressed state of the heart. The possibility of also expressing this coupling by using directly different areas under ESPVR has been indicated. A third method, not discussed here, is to use the windkessel model (see [27, 53]). c) The relationship between oxygen consumption and all the areas under ESPVR. d) A possible mechanism of adaptation to short- or long-term variation in load condition by changing ESPVR in a way to create an SWR (see Fig. 4 and Table 2). e) A possibility to use different areas under ESPVR for clinical diagnostic purposes (see [20]); an example for SWR and SWR/SW is given in Table. 2. f) A possibility of noninvasive clinical application of various results of this study. Item (f) depends on the possibility of noninvasive measurement of the left ventricular pressure, which has been reported by Bourguignon and Wagner [61], and Sato, et al. [62]. Noninvasive measurement of left ventricular dimensions has been discussed by Teichholz, et al. [63], Grassman, et al. [64], Dumesnil et al [65], Dumesnil and Shoucri [66, 67]. Measurement of ESPVR from one loop of the contraction cycle has also been discussed by Takeuchi, et al. [68] and Nakamoto, et al. [69]. Further readings can be found in [70] and [71]. The list of references is not exhaustive, but has been chosen to illustrate various related aspects of the topics discussed.