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Cardiac muscle cell disorganization in apical hypertrophic cardiomyopathy: a cardiac biopsy study
Shin-ichiro Morimoto1, Morie Sekiguchi, Akihisa Uemura
1Division of Cardiology, Department of Internal Medicine, Fujita Health University School of Medicine, Toyoake, Aichi, Japan.
Insights
Apical symmetric hypertrophy (AH) shows minimal cardiac muscle cell disorganization, unlike apical asymmetric septal hypertrophy (ASH). Histological analysis suggests AH may be a distinct subtype of hypertrophic cardiomyopathy (HCM).
Area of Science:
- Cardiology
- Histopathology
Background:
- Apical hypertrophic cardiomyopathy is classified into apical asymmetric septal hypertrophy (apical ASH) and apical symmetric hypertrophy (AH).
- Clinical differences exist between AH and ASH, raising questions about AH being a distinct hypertrophic cardiomyopathy (HCM) subtype.
Purpose of the Study:
- To compare the extent of cardiac muscle cell disorganization in patients with AH and ASH.
- To determine if histological findings support AH as a distinct entity within HCM.
Main Methods:
- Cardiac biopsy specimens from the left ventricular apex and interventricular septum were analyzed.
- Histologic characteristic of cardiac muscle cell disorganization was assessed and graded in patients with AH (n=10) and ASH (n=29).
Main Results:
- Cardiac muscle cell disorganization was virtually absent or limited in the AH group (1/10 with grade 1+).
- Significant cardiac muscle cell disorganization was observed in the ASH group (25/29 with grades 1+, 2+, or 3+).
- A statistically significant difference (P < 0.0001) in disorganization was found between the AH and ASH groups.
Conclusions:
- Histological findings indicate that apical symmetric hypertrophy (AH) differs significantly from typical hypertrophic cardiomyopathy (HCM) with apical asymmetric septal hypertrophy (ASH).
- The minimal cardiac muscle cell disorganization in AH supports its distinction from other forms of HCM.
Abstract:
Apical hypertrophic cardiomyopathy has been divided into two entities: apical asymmetric septal hypertrophy (apical ASH) and apical symmetric hypertrophy (AH). The latter differs clinically from hypertrophic cardiomyopathy (HCM) with ASH, and it is unclear whether AH represents a distinct subtype of HCM. In the present study, the presence or absence and the extent of cardiac muscle cell disorganization, a histologic characteristic of HCM, were compared in patients with AH (n = 10) and ASH (n = 29) in whom cardiac biopsy specimens were obtained from the left ventricular apex and interventricular septum. Disorganization was graded as (1+) in only 1 patient in the AH group and (-) in the remaining 9. In contrast, in the ASH group disorganization was graded as (1+) in 15 patients, (2+) in 7, (3+) in 3, and (-) in only 4 (P < 0.0001). Thus, it was observed that in AH disorganization is virtually absent or at most limited to a very narrow area. It is concluded from a histological stand point as well that the type of apical hypertrophic cardiomyopathy showing apical symmetric hypertrophy differs from usual HCM.
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