Time Course of Left Ventricular Pressure-Volume Relationship under Various Extents of Aortic Occlusion

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The author has reported that a variable, e(t)=p(t)/v(t), is approximately unchanged in the areflexive heart of the dog over a wide range of end-diastolic volume of the left ventricle, where p(t) is systolic left intraventricular pressure, v(t) is systolic left intraventricular volume, and t is time from the beginning of systole in each cardiac cycle. e(t) is studied further under various extents of an aortic occlusion, without the change in left intraventricular end-diastolic volume, monitored on left intraventricular end-diastolic pressure of the areflexive heart of the dog. For actual computation, e(t)=p(t)/{(1-ρ)-1•vs-∫toi(t)dt}, where p(t) is measured by a straingauge electromanometer, ρ is residual volume ratio measured by a thermodilution method, vs is stroke volume as time-integral of ascending aortic flow velocity i(t) in a given cardiac cycle, and i(t) is measured by an electromagnetic flowmeter. End-diastolic volumes of the left ventricle are kept approximately constant by controlling venous return to the heart with a balloon-catheter in the inferior vena cava. The results show that e(t) is approximately unchanged by an ascending aortic occlusion, in spite of the conspicuous changes in p(t), i(t) and v(t) in each dog. Therefore, e(t) is considered to be a steady and characteristic variable of the pumping properties of the areflexive left ventricle.
International Heart Journal刊行会の論文