Abstract
Objective : We investigated changes at the level of the muscular layers constructing the ventricular wall in patients with hypertrophic cardiomyopathy as well as their relation to disarray.
Materials : Twelve autopsied hearts (mean age 42 years) with HCM diagnosed clinically and at autopsy, and 7 controls (mean age 47 years) including hypertrophic hearts were macro--and microscopically studied.
Methods : We observed the macroscopic structure of the myocardial layers using a loupe, panoramic photographs of the transverse cut surfaces in the middle regions of both ventricles in 12 HCM cases.
We macroscopically scored the grade of disarrangement in the myocardial layer structure in the regions of the ventricular septum as well as anterior, lateral and posterior walls, and compared with the scores indicating the degree of disarray evaluated histologically. The myocyte orientation angle at ten points on the ventricular septum was also determined in 7 (mean age 29 years) of 12 HCM cases and compared with the 7 control hearts (mean age 47 years) including hypertrophic hearts.
Results : The median circular layer had disappeared in the ventricular septum of HCM and this was particularly obvious in cases with asymmetric septal hypertrophy. Disarrangement of the layer structure and the degree of disarray in the myocytes showed a rough positive correlation. The myocyte orientation angles at 5/10 (The fifth point from the endocardium of the left ventricle on the ventricular septum) and 6/10 (slightly outer to the fifth point) middle layer regions in the control group were relatively small at 15.6°±7.0°and 11.4. ±4.3°respectively, i. e., the angles were close to the horizontal circular shape, while the angles were significantly larger in the HCM group, 32.8°±8.5°and 22.0°±4.0°respectively (p<0.01).
Conclusions : In HCM, various degrees of structural abnormalities were seen not only at the cellular level or myocytic bundle level but also at the structural level of the layers. In particular, the normal layer--Structure was no longer macroscopically apparent in the median circular layer and this finding was marked in the ventricular septum.
Disarrangment of the layer structure and disarray at the myocytes were roughly correlated. The myocyte orientation angle in the ventricular septum was significantly larger in HCM, indicating the disappearance of the median circular layer.
