Zhou Yu-Qing, Bonafiglia Quinn A, Zhang Hangjun, Heximer Scott P, Bendeck Michelle P
Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, Toronto, Ontario, Canada.
Institute of Biomedical Engineering, Faculty of Applied Science and Engineering, University of Toronto, Toronto, Ontario, Canada.
Am J Physiol Heart Circ Physiol. 2023 Apr 1;324(4):H391-H410. doi: 10.1152/ajpheart.00590.2022. Epub 2023 Jan 6.
This study reports a new methodology for right heart imaging by ultrasound in mice under right ventricular (RV) pressure overload. Pulmonary artery constriction (PAC) or sham surgeries were performed on C57BL/6 male mice at 8 wk of age. Ultrasound imaging was conducted at 2, 4, and 8 wk postsurgery using both classical and advanced ultrasound imaging modalities including electrocardiogram (ECG)-based kilohertz visualization, anatomical M-mode, and strain imaging. Based on pulsed Doppler, the PAC group demonstrated dramatically enhanced pressure gradient in the main pulmonary artery (MPA) as compared with the sham group. By the application of advanced imaging modalities in novel short-axis views of the ventricles, the PAC group demonstrated increased thickness of RV free wall, enlarged RV chamber, and reduced RV fractional shortening compared with the sham group. The PAC group also showed prolonged RV contraction, asynchronous interplay between RV and left ventricle (LV), and passive leftward motion of the interventricular septum (IVS) at early diastole. Consequently, the PAC group exhibited prolongation of LV isovolumic relaxation time, without change in LV wall thickness or systolic function. Significant correlations were found between the maximal pressure gradient in MPA measured by Doppler and the RV systolic pressure by catheterization, as well as the morphological and functional parameters of RV by ultrasound. The established protocol overcomes the challenges in right heart imaging in mice, thoroughly elucidating the changes of RV, the dynamics of IVS, and the impact on LV and provides new insights into the pathophysiological mechanism of RV remodeling.
本研究报告了一种在右心室（RV）压力过载情况下对小鼠进行右心超声成像的新方法。对8周龄的C57BL/6雄性小鼠进行肺动脉缩窄（PAC）手术或假手术。在术后2周、4周和8周使用经典和先进的超声成像模式进行超声成像，包括基于心电图（ECG）的千赫兹可视化、解剖M型和应变成像。基于脉冲多普勒，与假手术组相比，PAC组主肺动脉（MPA）的压力梯度显著增强。通过在心室新的短轴视图中应用先进的成像模式，与假手术组相比，PAC组显示右室游离壁厚度增加、右室腔扩大以及右室分数缩短率降低。PAC组还表现出右室收缩延长、右室与左心室（LV）之间的异步相互作用以及舒张早期室间隔（IVS）的被动向左运动。因此，PAC组左室等容舒张时间延长，而左室壁厚度或收缩功能无变化。在通过多普勒测量的MPA最大压力梯度与通过导管插入术测量的右室收缩压之间，以及通过超声测量右室的形态和功能参数之间发现了显著相关性。所建立的方案克服了小鼠右心成像的挑战，全面阐明了右室的变化、室间隔的动态以及对左室的影响，并为右室重塑的病理生理机制提供了新的见解。
