Seemann Felicia, Berg Jonathan, Solem Kristian, Jablonowski Robert, Arheden Håkan, Carlsson Marcus, Heiberg Einar
Department of Clinical Sciences Lund, Clinical Physiology, Lund University, Skåne University Hospital, Lund, Sweden.
Department of Biomedical Engineering, Faculty of Engineering, Lund University, Lund, Sweden.
J Appl Physiol (1985). 2020 Oct 1;129(4):880-890. doi: 10.1152/japplphysiol.00198.2020. Epub 2020 Aug 20.
Left ventricular (LV) stroke work (SW) is calculated from the pressure-volume (PV) loop. PV loops do not contain information on longitudinal and radial pumping, leaving their contributions to SW unknown. A conceptual framework is proposed to derive the longitudinal and radial contributions to SW, using ventricular force-length loops reflecting longitudinal and radial pumping. The aim of this study was to develop and validate this framework experimentally and to explore these contributions in healthy controls and heart failure patients. Thirteen swine underwent cardiovascular magnetic resonance (CMR) and LV pressure catheterization at baseline ( = 7) or 1 wk after myocardial infarction ( = 6). CMR and noninvasive PV loop quantification were performed on 26 human controls and 14 patients. Longitudinal and radial forces were calculated as LV pressure multiplied by the myocardial surface areas in the respective directions. Length components were defined as the atrioventricular plane and epicardial displacements, respectively. Contributions to SW were calculated as the area within the respective force-length loop. Summation of longitudinal and radial SW had excellent agreement with PV loop-derived SW (ICC = 0.95, = 0.96, bias ± SD = -4.5 ± 5.4%) in swine. Longitudinal and radial contributions to SW were ~50/50% in swine and human controls, and 44/56% in patients. Longitudinal pumping required less work than radial to deliver stroke volume in swine (6.8 ± 0.8 vs. 8.7 ± 1.2 mJ/mL, = 0.0002) and in humans (11 ± 2.1 vs. 17 ± 4.7 mJ/mL, < 0.0001). In conclusion, longitudinal and radial pumping contribute ~50/50% to SW in swine and human controls and 44/56% in heart failure patients. Longitudinal pumping is more energy efficient than radial pumping in delivering stroke volume. A novel method for quantifying the contributions of longitudinal and radial pumping to stroke work using global left ventricular force-length loops was proposed and validated, which can be quantified noninvasively using cardiovascular magnetic resonance and brachial cuff pressure. We found that longitudinal and radial pumping contributes equally to stroke work in controls and 44/56% in heart failure patients, and that the longitudinal pumping is more energy efficient in delivering stroke volume than radial pumping.
左心室（LV）每搏功（SW）由压力-容积（PV）环计算得出。PV环不包含纵向和径向泵血的信息，因此它们对SW的贡献尚不清楚。本文提出了一个概念框架，利用反映纵向和径向泵血的心室力-长度环来推导SW的纵向和径向贡献。本研究的目的是通过实验开发和验证该框架，并在健康对照者和心力衰竭患者中探究这些贡献。13头猪在基线时（n = 7）或心肌梗死后1周（n = 6）接受了心血管磁共振（CMR）和左心室压力导管插入术。对26名人类对照者和14名患者进行了CMR和无创PV环定量分析。纵向和径向力通过左心室压力乘以各自方向上的心肌表面积来计算。长度分量分别定义为房室平面和心外膜位移。SW的贡献通过各自力-长度环内的面积来计算。在猪中，纵向和径向SW的总和与PV环得出的SW具有极好的一致性（组内相关系数ICC = 0.95，R² = 0.96，偏差±标准差= -4.5±5.4%）。在猪和人类对照者中，SW的纵向和径向贡献约为50/50%，在患者中为44/56%。在猪中（6.8±0.8 vs. 8.7±1.2 mJ/mL，P = 0.0002）和人类中（11±2.1 vs. 17±4.7 mJ/mL，P < 0.0001），输送每搏量时纵向泵血所需的功比径向泵血少。总之，在猪和人类对照者中，纵向和径向泵血对SW的贡献约为50/50%，在心力衰竭患者中为44/56%。在输送每搏量时，纵向泵血比径向泵血更节能。本文提出并验证了一种使用整体左心室力-长度环量化纵向和径向泵血对每搏功贡献的新方法，该方法可通过心血管磁共振和肱动脉袖带压力进行无创量化。我们发现，在对照者中，纵向和径向泵血对每搏功的贡献相等，在心力衰竭患者中为44/56%，并且在输送每搏量时，纵向泵血比径向泵血更节能。
