Nakaji Kosuke, Itatani Keiichi, Tamaki Nagara, Morichi Hiroko, Nakanishi Naohiko, Takigami Masao, Yamagishi Masaaki, Yaku Hitoshi, Yamada Kei
Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Department of Cardiovascular Surgery, Cardiovascular Imaging Research Laboratory, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
J Cardiol. 2021 Jul;78(1):79-87. doi: 10.1016/j.jjcc.2021.01.004. Epub 2021 Jan 31.
Biventricular physiological interaction remains a challenging problem in cardiology. We developed a four-dimensional (4D) flow magnetic resonance imaging (MRI) scan and clinically available analysis protocol based on beat tracking of the cardiovascular lumen without contrast medium, which enabled measurement of the biventricular hemodynamics and energetic performance by calculating flow energy loss (EL) and kinetic energy (KE). The aim of this study was to observe the flow patterns and energy dynamics to reveal the physiology of the right and left ventricular systems.
4D flow MRI studies were performed in 19 healthy volunteers including 11 male and 8 female. The right and left ventricular systems were segmented to visualize the flow patterns and to quantify the hemodynamics and energy dynamics.
A large vortex was observed in the left ventricle (LV), along the longitudinal axis, during end diastole and early systole. At early systole, the vortex appeared to facilitate smooth ejection with little EL. In contrast, in the right ventricle (RV), there were vortices near the free wall in both the short and long axes during the diastolic filling phase. Mean EL index during a single cardiac cycle in the right and left heart systems was 0.63 ± 0.16 (0.42-0.99) mW/m, and 1.02 ± 0.26 (0.58-1.58) mW/m, respectively. EL is inevitable loss caused by the vortex flow to facilitate smooth right and left ventricular function and left-sided EL tended to correlate positively with heart rate and right ventricular stroke volume. Kinetic energy at the aortic valve was influenced by LV end-diastolic volume/stroke volume. No gender difference was observed.
The RV appears to function as a regulator of the energy dynamics of the LV system.
双心室生理相互作用仍是心脏病学中一个具有挑战性的问题。我们开发了一种基于心血管腔搏动追踪的四维（4D）流动磁共振成像（MRI）扫描及临床可用分析方案，无需使用造影剂，通过计算流动能量损失（EL）和动能（KE）能够测量双心室血流动力学和能量性能。本研究的目的是观察血流模式和能量动态，以揭示右心室和左心室系统的生理情况。
对19名健康志愿者（11名男性和8名女性）进行了4D流动MRI研究。对右心室和左心室系统进行分割，以可视化血流模式并量化血流动力学和能量动态。
在舒张末期和收缩早期，左心室（LV）沿纵轴观察到一个大的涡流。在收缩早期，该涡流似乎有助于平稳射血，且能量损失很小。相比之下，在右心室（RV），舒张期充盈阶段在短轴和长轴的游离壁附近均存在涡流。右心系统和左心系统在单个心动周期中的平均EL指数分别为0.63±0.16（0.42 - 0.99）mW/m和1.02±0.26（0.58 - 1.58）mW/m。EL是涡流导致的不可避免的损失，以促进右心室和左心室功能平稳，且左侧EL往往与心率和右心室每搏输出量呈正相关。主动脉瓣处的动能受左心室舒张末期容积/每搏输出量的影响。未观察到性别差异。
右心室似乎起到左心室系统能量动态调节器的作用。
