Starling M R, Walsh R A, Dell'Italia L J, Mancini G B, Lasher J C, Lancaster J L
Circulation. 1987 Jul;76(1):32-43. doi: 10.1161/01.cir.76.1.32.
This investigation was designed to calculate left ventricular maximum time-varying elastance (Emax), to define the relationship between Emax and pressure-volume (P-V) relations at other, more easily defined measured of end-systole, and to determine whether these measures of left ventricular contractile function can be normalized in man. Accordingly, we studied 10 subjects with simultaneous high-fidelity micromanometer left ventricular and ascending aortic pressure recordings and biplane contrast cineangiograms at control conditions and during infusion of methoxamine and nitroprusside. Emax was defined as the maximum slope of the linear relation of isochronal, instantaneous P-V data points obtained from each of the three loading conditions. Left ventricular end-systole was also defined for each loading condition as: the time of the maximum P-V ratio (maxPV), minimum ventricular volume (minPV), (-)dP/dtmin [(-)dP/dtPV], and zero systolic flow approximated by the central aortic dicrotic notch (AodiPV). The mean heart rates and LV (+)dP/dtmax were insignificantly altered during the three loading conditions. Isochronal Emax ranged from 3.38 to 6.73 mm Hg/ml (mean 5.48 +/- 1.23 [SD] mm Hg/ml) and the volume-axis intercepts at zero pressure ranged from -2 to 51 ml (mean 18 +/- 16 ml). The isochronal slope calculations were reproducible (r = .97 to .99). The end-systolic P-V slope values for the maxPV, minPV, (-)dP/dtPV, and AodiPV relations correlated with isochronal Emax (r = .90, .88, .69, and .74, respectively). The average slope values for these end-systolic P-V relations, however, underestimated the mean Emax (p less than .01 to p less than .001). The mean extrapolated volume-axis intercepts for these end-systolic P-V relations also underestimated that for Emax. Finally, the isochronal Emax and other end-systolic P-V relation slope values demonstrated inverse linear relationships with left ventricular mass (r = -.68 to -.91, p less than .05 to p less than .001). Only the Emax volume-axis intercepts showed a linear relationship with left ventricular end-diastolic volume (r = .75). Thus we conclude that the time-varying elastic properties of the left ventricle can be calculated in man, that commonly used end-systolic P-V relations significantly underestimate isochronal Emax, and that normalization of isochronal Emax and other end-systolic P-V relation slope values might be performed in man with left ventricular mass; no obvious relationship between volume-axis intercepts and measures of left ventricular or body size was apparent.
本研究旨在计算左心室最大时变弹性（Emax），确定Emax与其他更易定义的收缩末期测量指标的压力-容积（P-V）关系，并确定这些左心室收缩功能指标在人体中是否可以标准化。因此，我们研究了10名受试者，在对照条件下以及在静脉输注甲氧明和硝普钠期间，同时进行高保真微测压左心室和升主动脉压力记录以及双平面造影电影血管造影。Emax定义为从三种负荷条件中的每一种获得的等时、瞬时P-V数据点的线性关系的最大斜率。每种负荷条件下的左心室收缩末期也定义为：最大P-V比值（maxPV）、最小心室容积（minPV）、（-）dP/dtmin [（-）dP/dtPV]以及由主动脉中央重搏波切迹近似的零收缩期血流（AodiPV）的时间。在三种负荷条件下，平均心率和左心室（+）dP/dtmax的变化不显著。等时Emax范围为3.38至6.73 mmHg/ml（平均5.48±1.23 [标准差] mmHg/ml），零压力下的容积轴截距范围为-2至51 ml（平均18±16 ml）。等时斜率计算具有可重复性（r = 0.97至0.99）。maxPV、minPV、（-）dP/dtPV和AodiPV关系的收缩末期P-V斜率值与等时Emax相关（分别为r = 0.90、0.88、0.69和0.74）。然而，这些收缩末期P-V关系的平均斜率值低估了平均Emax（p < 0.01至p < 0.001）。这些收缩末期P-V关系的平均外推容积轴截距也低估了Emax的截距。最后，等时Emax和其他收缩末期P-V关系斜率值与左心室质量呈负线性关系（r = -0.68至-0.91，p < 0.05至p < 0.001）。只有Emax容积轴截距与左心室舒张末期容积呈线性关系（r = 0.75）。因此，我们得出结论，左心室的时变弹性特性在人体中可以计算，常用的收缩末期P-V关系显著低估等时Emax，等时Emax和其他收缩末期P-V关系斜率值可能可以根据左心室质量在人体中进行标准化；容积轴截距与左心室或身体大小测量指标之间没有明显关系。
