Pulmonary Diseases, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
J Heart Lung Transplant. 2013 Jan;32(1):50-5. doi: 10.1016/j.healun.2012.09.022. Epub 2012 Nov 17.
End-systolic elastance (E(es)), a load-independent measure of ventricular function, is of clinical interest for studies of the right ventricle (RV) in patients with pulmonary arterial hypertension (PAH). The objective of this study was to determine whether, in PAH patients, E(es) can be estimated from mean pulmonary artery pressure (mPAP) and end-systolic volume (ESV) only.
Right heart catheterization was used to measure mPAP. Maximal isovolumic pressure (P(iso)) was estimated from RV pressure curves with the so-called single-beat method. Cardiac magnetic resonance imaging (MRI) was used to assess RV end-diastolic and end-systolic volumes (EDV and ESV). E(es) was then calculated as: E(es) = (P(iso)-mPAP) / (EDV-ESV), and as E(es,V0 = 0) = mPAP/ESV (simplified method, with V0 = 0, is negligible volume at zero pressure). Right ventricular volume at zero pressure (V(0)) was then defined as the intercept of the end-systolic pressure-volume relation (single-beat method) with the horizontal axis.
E(es,V0 = 0) was significantly lower compared with E(es) (0.61 vs 1.34 mm Hg/ml, respectively, p<0.01). A modified Bland-Altman analysis showed a contractility-dependent difference between E(es,V0 = 0) and E(es). Moreover, V(0) ranged from-8 up to 171 ml, and a moderate and good correlation was found between V(0) and EDV, and V(0) and ESV, respectively (r = 0.65 and r = 0.87, p< 0.01).
These findings show that V(0) is dependent on RV dilation. Therefore, the assumption that V(0) is negligible in PAH is incorrect. Consequently, for an accurate assessment of load-independent RV systolic function, RV volumes and pressure curves are required.
收缩末期弹性（E(es)）是一种心室功能的非负荷依赖性测量指标，对于肺动脉高压（PAH）患者右心室（RV）的研究具有临床意义。本研究的目的是确定在 PAH 患者中，是否仅通过平均肺动脉压（mPAP）和收缩末期容积（ESV）即可估计 E(es)。
使用右心导管术测量 mPAP。使用所谓的单次心跳法从 RV 压力曲线中估计最大等容压力（P(iso)）。心脏磁共振成像（MRI）用于评估 RV 舒张末期和收缩末期容积（EDV 和 ESV）。然后，E(es) 计算为：E(es) = (P(iso)-mPAP) / (EDV-ESV)，以及 E(es,V0 = 0) = mPAP/ESV（简化方法，V0 = 0，是零压力下的可忽略体积）。然后将零压力下的 RV 容积（V(0)）定义为单次心跳法收缩末期压力-容积关系与横轴的交点。
E(es,V0 = 0)明显低于 E(es)（分别为 0.61 毫米汞柱/毫升和 1.34 毫米汞柱/毫升，p<0.01）。改良的 Bland-Altman 分析显示，E(es,V0 = 0)和 E(es)之间存在收缩依赖性差异。此外，V(0)范围从-8 到 171 毫升，并且 V(0)与 EDV 之间存在中度和良好的相关性，与 ESV 之间也存在中度和良好的相关性（r = 0.65 和 r = 0.87，p<0.01）。
这些发现表明 V(0)取决于 RV 扩张。因此，PAH 中 V(0)可忽略不计的假设是不正确的。因此，为了准确评估非负荷依赖性 RV 收缩功能，需要 RV 容积和压力曲线。
