[Evaluation of left ventricular asynergy by parasternal and subcostal M-mode echocardiography]

In 47 patients with old myocardial infarction (MI), parasternal and subcostal M-mode echocardiograms (M-mode) guided by the two-dimensional echocardiogram (2D) were recorded to evaluate left ventricular asynergy quantitatively, and were compared with 2D findings. By placing the transducer at the left sternal border, the short-axis views of the left ventricle (LV) by 2D at the level of the chorda tendineae and papillary muscle were recorded. The LV wall was divided into 4 segments; including (1) anterior wall (AW) and anterior septum (AS), (2) lateral wall (LW), (3) posterior wall (PW), and (0) inferior wall (IW) and posterior septum (PS), and asynergy was analyzed on moving images. The AS and PW were recorded by parasternal M-mode, and the PS and LW were recorded by subcostal approach. Asynergy by M-mode was defined when septal amplitude was less than 3 mm, LW or PW amplitude was less than 9 mm, % systolic thickening (% ST) of the septum was less than 17%, and % ST of the LW or PW was less than 25%. Of 25 patients with anterior MI, asynergy of the AW and AS wass s present in 19, LW asynergy in 10, PW asynergy in 2, and IW and PS asynergy in 1 by 2D, meanwhile, M-mode detected asynergy of AS in 21, and LW asynergy in 15. Of 15 patients with inferior MI, asynergy of the PW and PS was present in 4 and 7, respectively by 2D, but by M-mode asynergy was present in 11 and 14, respectively. In 31 patients underwent left ventricular cineangiography, detection rate of asynergy by angiography was compared with that by echocardiography. In 124 segments by cineangiography, wall motion characteristics were correctly identified in 83% by 2D and 91% by M-mode. Of 25 patients with anterior MI, amplitude of the AS was 3 approximately -5 mm in 19, and %ST of the AS wa 0 approximately 6% in 2, but amplitude of the PS was within normal range in 24. Of 15 patients with inferior MI, amplitude of the AS was within normal range in all, and amplitude of PS was 3 approximately -8 mm in 13 and %ST of PS was 10% in 1. This study shows that combined use of parasternal and subcostal M-mode detects asynergy more sensitively than 2D alone even in its quantitative sense, and therefore, not only 2D but M-mode in essential for evaluation of LV asynergy. Asynergy of PS was present in inferior MI, and this segment was not injured in anterior MI, while AS asynergy was present in anterior MI. When analysing asynergy of the interventricular septum, it should be subdivided into two parts including AS and PS. Subcostal M-mode detected PS asynergy that was not visualized by routine cineangiography. In inferior MI, subcostal M-mode is recommended for detection of PS asynergy.