Cong Zhibin, Jiang Bin, Lu Jianbo, Cong Yunyi, Fu Jili, Jin Mingyue, Wang Xue
Department of Electrodiagnosis, Changchun University of Traditional Chinese Medicine, Changchun Department of Ultrasonography, The First Hospital of China Medical University, Shengyang Bethune Medical College, Jilin University, Changchun, China.
Medicine (Baltimore). 2018 May;97(21):e10770. doi: 10.1097/MD.0000000000010770.
Clinically the isovolumic contraction time (IVCT) can be measured by 3 echocardiographic methods of M-mode, pulse-wave Doppler (PWD), and tissue Doppler imaging (TDI). But IVCT can be clinically different by the 3 methods. This study is to investigate whether there is a potentially unidentified phase causing the discrepancies by analyzing electric mechanical delay time (EMD), IVCT, and pre-ejection period (PEP).A total of 30 healthy subjects were recruited for the study. EMD, IVCT, and PEP were obtained by the 3 methods, respectively. MCT (the interval from the onset of the QRS wave to the closure point of the mitral valve measured by TDI) and ICMC (the interval from the onset of IVC wave S1 to the closure point of the mitral valve measured by TDI) were both measured by color TDI.IVCTt (IVCT measured by TDI) was significantly longer than IVCTm or IVCTd (IVCT measured by M-mode or PWD) (both P < .0001), while EMDt (EMD measured by TDI) was significantly shorter than EMDm or EMDd (EMD measured by M-mode or PWD) (both P < .0001). But MCT was not significantly different from EMDm or EMDd (P > .05) and ICMC did not differ significantly from EMDm or EMDd minus EMDt or IVCTt minus IVCTm or IVCTd (P > .05), in other words, ICMC almost equaled to (EMDm or EMDd minus EMDt) or (IVCTt minus IVCTm or IVCTd).There may be an unidentified phase between the end of atrial contraction and the closure of mitral valve causing the discrepancies in IVCT, which is named as the pre-isovolumic contraction phase. It is a non-isovolumic phase and is included in the traditional isovolumic contraction phase.
临床上，等容收缩期（IVCT）可通过M型、脉冲波多普勒（PWD）和组织多普勒成像（TDI）这三种超声心动图方法进行测量。但通过这三种方法测得的临床IVCT可能存在差异。本研究旨在通过分析电机械延迟时间（EMD）、IVCT和射血前期（PEP），探讨是否存在一个潜在未被识别的阶段导致这些差异。
本研究共招募了30名健康受试者。分别通过这三种方法获取EMD、IVCT和PEP。MCT（通过TDI测量的从QRS波起始到二尖瓣关闭点的间期）和ICMC（通过TDI测量的从IVC波S1起始到二尖瓣关闭点的间期）均通过彩色TDI进行测量。
IVCTt（通过TDI测量的IVCT）显著长于IVCTm或IVCTd（通过M型或PWD测量的IVCT）（均P<0.0001），而EMDt（通过TDI测量的EMD）显著短于EMDm或EMDd（通过M型或PWD测量的EMD）（均P<0.0001）。但MCT与EMDm或EMDd无显著差异（P>0.05），ICMC与EMDm或EMDd减去EMDt或IVCTt减去IVCTm或IVCTd无显著差异（P>0.05），换句话说，ICMC几乎等于（EMDm或EMDd减去EMDt）或（IVCTt减去IVCTm或IVCTd）。
在心房收缩末期与二尖瓣关闭之间可能存在一个未被识别的阶段，导致IVCT出现差异，该阶段被命名为预等容收缩期。它是一个非等容阶段，包含在传统的等容收缩期内。
