Misbach G A, Glantz S A
Am J Physiol. 1979 Dec;237(6):H644-8. doi: 10.1152/ajpheart.1979.237.6.H644.
Systolic performance depends on end-diastolic muscle fiber length, contractility, and afterload. Ventricular function curves are constructed using end-diastolic pressure instead of end-diastolic dimensions, on the assumption that end-diastolic pressure and end-diastolic dimensions (reflecting muscle fiber length) have a constant relation. That assumption has been rejected. Theorectically, ventricular function curves should change with changes in the diastolic pressure-dimension relation as well as with contractility or afterload. We measured pressures and dimensions in ventricles of six open-chest dogs before and after opening the pericardium to alter diastolic pressure-dimension relations with afterload constant. When an indicator of systolic performance (developed pressure times diameter change during systole) was plotted against end-diastolic pressure, data obtained with the pericardium closed and open resulted in two distinct curves, suggesting an increase in contractility with the pericardium open. However, when systolic performance was plotted against end-diastolic diameter, data obtained with the pericardiumclosed and open fell along one curve, indicating no change in contractility. Therefore, changes in the diastolic pressure-dimension relation to shift conventional ventricular function curves.
收缩功能取决于舒张末期肌纤维长度、收缩力和后负荷。心室功能曲线是用舒张末期压力而非舒张末期尺寸构建的，其假设是舒张末期压力和舒张末期尺寸（反映肌纤维长度）具有恒定关系。该假设已被否定。理论上，心室功能曲线应随舒张期压力-尺寸关系的变化以及收缩力或后负荷的变化而改变。我们在六只开胸犬的心室中测量了压力和尺寸，在保持后负荷恒定的情况下，打开心包前后改变舒张期压力-尺寸关系。当将收缩功能指标（收缩期压力乘以直径变化）与舒张末期压力作图时，心包关闭和打开时获得的数据形成两条不同的曲线，表明心包打开时收缩力增加。然而，当将收缩功能与舒张末期直径作图时，心包关闭和打开时获得的数据落在一条曲线上，表明收缩力无变化。因此，舒张期压力-尺寸关系的变化会使传统心室功能曲线发生移位。
