Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.
KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway.
Am J Physiol Heart Circ Physiol. 2020 Jan 1;318(1):H143-H153. doi: 10.1152/ajpheart.00357.2019. Epub 2019 Nov 27.
The function of the right ventricle (RV) is linked to clinical outcome in many cardiovascular diseases, but its role in experimental heart failure remains largely unexplored due to difficulties in measuring RV function in vivo. We aimed to advance RV imaging by establishing phase-contrast MRI (PC-MRI) as a robust method for measuring RV function in rodents. A total of 46 Wistar-Hannover rats with left ventricular (LV) myocardial infarction and 10 control rats (sham) were examined 6 wk after surgery. Using a 9.4-T preclinical MRI system, we utilized PC-MRI to measure strain/strain rate in the RV free wall under isoflurane anesthesia. Cine MRI was used to measure RV volumes. LV end-diastolic pressure (LVEDP) was measured and used to identify pulmonary congestion. The infarct rats were divided into two groups: those with signs of pulmonary congestion (PC), with LVEDP ≥ 15 mmHg ( = 26) and those without signs of pulmonary congestion (NPC), with LVEDP < 15 mmHg ( = 20). The NPC rats exhibited preserved RV strains/strain rates, whereas the PC rats exhibited reduced strains/strain rates (26-48% lower than sham). Of the strain parameters, longitudinal strain and strain rate exhibited the highest correlations to LVEDP and lung weight (rho = 0.65-0.72, < 0.001). Basal longitudinal strain was most closely associated with signs of pulmonary congestion and indexes of RV remodeling. Longitudinal RV strain had higher area under the curve than ejection fraction for detecting subtle RV dysfunction (area under the curve = 0.85 vs. 0.67). In conclusion, we show for the first time that global and regional RV myocardial strain can be measured robustly in rodents. Reduced RV strain was closely associated with indexes of pulmonary congestion and molecular markers of RV remodeling. Global and regional right ventricular myocardial strain can be measured with high reproducibility and low interobserver variability in rodents using tissue phase mapping MRI. Reduced right ventricular strain was associated with indexes of pulmonary congestion and molecular markers of right ventricular remodeling. Regional strain in the basal myocardium was considerably higher than in the apical myocardium.
右心室（RV）的功能与许多心血管疾病的临床结果相关，但由于难以在体内测量 RV 功能，其在实验性心力衰竭中的作用在很大程度上仍未得到探索。我们旨在通过建立相位对比 MRI（PC-MRI）作为测量啮齿动物 RV 功能的强大方法来推进 RV 成像。共有 46 只 Wistar-Hannover 大鼠接受左心室（LV）心肌梗死手术，10 只对照大鼠（假手术）接受手术。使用 9.4-T 临床前 MRI 系统，我们在异氟烷麻醉下利用 PC-MRI 测量 RV 游离壁的应变/应变速率。电影 MRI 用于测量 RV 容积。测量 LV 舒张末期压（LVEDP），并用于识别肺充血。将梗死大鼠分为两组：有肺充血迹象的组（PC 组，LVEDP≥15mmHg，=26）和无肺充血迹象的组（NPC 组，LVEDP<15mmHg，=20）。NPC 大鼠表现出保留的 RV 应变/应变速率，而 PC 大鼠表现出降低的应变/应变速率（比假手术组低 26-48%）。在应变参数中，纵向应变和应变速率与 LVEDP 和肺重量的相关性最高（rho=0.65-0.72，<0.001）。基础纵向应变与肺充血迹象和 RV 重构指标最密切相关。纵向 RV 应变在检测微妙 RV 功能障碍方面比射血分数具有更高的曲线下面积（曲线下面积=0.85 比 0.67）。总之，我们首次表明，在啮齿动物中可以稳健地测量整体和局部 RV 心肌应变。RV 应变降低与肺充血指标和 RV 重构的分子标志物密切相关。使用组织相位映射 MRI，在啮齿动物中可以以高重复性和低观察者间变异性测量整体和局部 RV 心肌应变。RV 应变降低与肺充血指标和 RV 重构的分子标志物相关。基底部心肌的局部应变明显高于心尖部。
