Department of Clinical Sciences, Clinical Physiology, Skåne University Hospital, Lund University, 221 85, Lund, Sweden.
Department of Clinical Sciences, Pediatric Heart Center, Skåne University Hospital, Lund University, Lund, Sweden.
BMC Cardiovasc Disord. 2022 Jun 6;22(1):253. doi: 10.1186/s12872-022-02686-7.
Pressure-volume (PV) loops provide comprehensive information of cardiac function, but commonly implies an invasive procedure under general anesthesia. A novel technique has made it possible to non-invasively estimate PV loops with cardiac magnetic resonance (CMR) and brachial pressure which would enable good volume estimation of often anatomically complex ventricles without the need of anesthesia in most cases. In this study we aimed to compare how hemodynamic parameters derived from PV loops in patients with Fontan circulation differ to controls.
Patients with Fontan circulation (n = 17, median age 12 years, IQR 6-15) and healthy controls (n = 17, 14 years, IQR 13-22) were examined with CMR. Short axis balanced steady-state free-precession cine images covering the entire heart were acquired. PV loops were derived from left ventricular volumes in all timeframes and brachial blood pressure from cuff sphygmomanometry.
Fontan patients had lower stroke work, ventricular mechanical efficiency and external power compared to controls. Fontan patients with dominant right ventricle had higher potential energy indexed to body surface area but lower contractility (Ees) compared to controls. Fontan patients had higher arterial elastance (Ea) and Ea/Ees ratio than controls. Contractility showed no correlation with ejection fraction (EF) in Fontan patients irrespective of ventricular morphology. No difference was seen in energy per ejected volume between Fontan patients and controls.
This non-invasive PV-loop method could be used in future studies to show the potential prognostic value of these measures and if changes in ventricular function over time can be detected earlier by this method compared to changes in ventricular volumes and EF. In contrast to patients with acquired heart failure, Fontan patients had similar energy per ejected volume as controls which suggests similar ventricular oxygen consumption to deliver the same volume in Fontan patients as in controls.
压力-容积（PV）环提供了心脏功能的综合信息，但通常需要在全身麻醉下进行有创操作。一种新的技术使得通过心脏磁共振（CMR）和肱动脉血压无创估计 PV 环成为可能，这使得在大多数情况下无需麻醉即可对通常解剖结构复杂的心室进行良好的容量估计。在这项研究中，我们旨在比较法洛四联症患者的 PV 环衍生的血流动力学参数与对照组的差异。
对 17 例法洛四联症患者（中位年龄 12 岁，IQR 6-15 岁）和 17 例健康对照组（14 岁，IQR 13-22 岁）进行 CMR 检查。采集覆盖整个心脏的左心室容积的短轴平衡稳态自由进动电影图像。从所有时间点的左心室容积和袖带血压测量得出 PV 环。
法洛四联症患者的心脏做功、心室机械效率和外部功率均低于对照组。右心室优势的法洛四联症患者的势能指数与体表面积相关较高，但与对照组相比，收缩性（Ees）较低。法洛四联症患者的动脉弹性（Ea）和 Ea/Ees 比值高于对照组。法洛四联症患者的收缩性与射血分数（EF）无关，与 EF 无相关性。法洛四联症患者和对照组的每搏输出量的能量无差异。
这种非侵入性的 PV 环方法可用于未来的研究，以显示这些措施的潜在预后价值，如果与心室容积和 EF 的变化相比，这种方法是否可以更早地检测到心室功能随时间的变化。与获得性心力衰竭患者不同，法洛四联症患者的每搏输出量的能量与对照组相似，这表明在法洛四联症患者中，输送相同体积的心室氧耗与对照组相似。
