Temporal relationship between left ventricular and arterial system elastances

The authors investigated the temporal relationship of arterial compliance to ventricular elastance of the left ventricle (E/sub lv/(t)) in five open-chest anesthetized dogs, where simultaneous aortic pressure and flow and left-ventricular pressure were measured. E/sub lv/(t) was derived using an elastance-resistance model of the left ventricle. The nonlinear pressure-dependent compliance (C(P)) of the arterial system was incorporated in a three-element Windkessel model and determined by accurate prediction of aortic pressure from aortic flow. The resulting arterial elastance E/sub as/(t) was computed as E/sub as/(t)=1/C(P). Results show that E/sub as/(t) reaches a minimum value at or near the start of ventricular ejection and attains its peak value at or near the time that maximum left ventricular elastance is reached, at end-systole. Numerical simulation of the model demonstrates its ability to adequately reproduce measured pressure and flow. Thus, the arterial system, in terms of elastance, is dynamically and temporally coupled to the left-ventricle during ejection.<
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