Department of Clinical Physiology, Lund University, Skåne University Hospital (F.S., P.A., D.N., S.K., M.C., H.A., E.H.).
Department of Biomedical Engineering (F.S., E.H.), Lund University, Sweden.
Circ Cardiovasc Imaging. 2019 Dec;12(1):e008493. doi: 10.1161/CIRCIMAGING.118.008493.
Pressure-volume (PV) loops provide a wealth of information on cardiac function but are not readily available in clinical routine or in clinical trials. This study aimed to develop and validate a noninvasive method to compute individualized left ventricular PV loops.
The proposed method is based on time-varying elastance, with experimentally optimized model parameters from a training set (n=5 pigs), yielding individualized PV loops. Model inputs are left ventricular volume curves from cardiovascular magnetic resonance imaging and brachial pressure. The method was experimentally validated in a separate set (n=9 pig experiments) using invasive pressure measurements and cardiovascular magnetic resonance images and subsequently applied to human healthy controls (n=13) and patients with heart failure (n=28).
There was a moderate-to-excellent agreement between in vivo-measured and model-calculated stroke work (intraclass correlation coefficient, 0.93; bias, -0.02±0.03 J), mechanical potential energy (intraclass correlation coefficient, 0.57; bias, -0.04±0.03 J), and ventricular efficiency (intraclass correlation coefficient, 0.84; bias, 3.5±2.1%). The model yielded lower ventricular efficiency ( P<0.0001) and contractility ( P<0.0001) in patients with heart failure compared with controls, as well as a higher potential energy ( P<0.0001) and energy per ejected volume ( P<0.0001). Furthermore, the model produced realistic values of stroke work and physiologically representative PV loops.
We have developed the first experimentally validated, noninvasive method to compute left ventricular PV loops and associated quantitative measures. The proposed method shows significant agreement with in vivo-derived measurements and could support clinical decision-making and provide surrogate end points in clinical heart failure trials.
压力-容积（PV）环提供了丰富的心脏功能信息，但在临床常规或临床试验中并不容易获得。本研究旨在开发和验证一种非侵入性方法来计算个体左心室 PV 环。
所提出的方法基于时变弹，使用来自训练集（n=5 头猪）的经过实验优化的模型参数，生成个体 PV 环。模型输入是心血管磁共振成像和肱动脉压力的左心室容积曲线。该方法在一个独立的数据集（n=9 头猪实验）中使用侵入性压力测量和心血管磁共振成像进行了实验验证，随后应用于健康对照者（n=13）和心力衰竭患者（n=28）。
体内测量和模型计算的每搏功（组内相关系数，0.93；偏倚，-0.02±0.03 J）、机械势能（组内相关系数，0.57；偏倚，-0.04±0.03 J）和心室效率（组内相关系数，0.84；偏倚，3.5±2.1%）之间存在中度至极好的一致性。与对照组相比，心力衰竭患者的心室效率（P<0.0001）和收缩性（P<0.0001）较低，势能（P<0.0001）和每搏射血量的能量（P<0.0001）较高。此外，该模型产生了现实的每搏功和生理代表性的 PV 环值。
我们开发了第一个经过实验验证的非侵入性方法来计算左心室 PV 环和相关的定量测量值。所提出的方法与体内衍生的测量值具有显著的一致性，可支持临床决策，并为心力衰竭临床试验提供替代终点。
