Quantitative analysis of the distribution of cardiac muscle cell disorganization in the left ventricular wall of patients with hypertrophic cardiomyopathy.
Authors: B J Maron, T J Anan, W C Roberts
Journal: Circulation (1981)

The distribution of cardiac muscle cell disorganization in different regions of the left ventricular wall was studied quantitatively in 52 patients with hypertrophic cardiomyopathy.Cellular disorganiza- tion in the ventricular septum was both common and extensive (mean area of septal tissue section disorganized, 35 i 4%).Disorganization was also substantial (24 ± 3%) in the left ventricular free wall of these patients, although less marked than in the ventricular septum (p < 0.05).Anterior left ventricular free wall disorganization was particularly extensive (32 ± 4%) and did not differ significantly from that present in the ven- tricular septum.Marked cardiac muscle cell disorganization (> 5% of the tissue section) was diffusely dis- tributed in the ventricular septum and left ventricular free wall in 33 of the 52 patients (63%).Particularly marked left ventricular free wall and combined free wall and septal disorganization was present in 14 patients without functional limitation in whom sudden death occurred early in life (< 25 years of age) and was the initial manifestation of cardiac disease.In contrast, although abnormally arranged cardiac muscle cells were identified in the left ventricular free wall in 47% of patients with other congenital or acquired heart diseases or normal hearts, this disorganization was usually limited in extent (mean area of section disorganized, 2 0.5%).Hence, in a large population of patients with hypertrophic cardiomyopathy, cellular disorganization was widely distributed throughout both the ventricular septum and left ventricular free wall.No definitive con- clusions can be made regarding the significance of this distribution of cellular disorganization; however, our data suggest that this pattern may represent a diffuse cardiomyopathic process and be a determinant of clinical outcome in certain patients with hypertrophic cardiomyopathy.HYPERTROPHIC CARDIOMYOPATHY is a disease of cardiac muscle that is characterized by a hypertrophied, nondilated left ventricle' and, in most patients, asymmetric septal hypertrophy.2`6Marked disorganization of cardiac muscle cells in the ventric- ular septum7-10 has also been shown by quantitative histologic analysis to be a highly specific and sensitive anatomic hallmark of hypertrophic cardiomyopathy.1''3 Qualitative histologic studies have shown that cellular disorganization may also be present in the left ventricular free wall of patients with hypertrophic cardiomyopathy.?' ' In this study, we quan- titated, for the first time, the extent of cellular dis- organization in both the ventricular septum and left ventricular free wall of patients with hypertrophic cardiomyopathy compared with patients with other forms of cardiac hypertrophy; we also determined whether the distribution and extent of the cellular disorganization in patients with hypertrophic cardio- myopathy has significance with regard to clinical course or hemodynamic state. Selection of Case MaterialPatients with Hypertrophic CardiomyopathyThe cardiovascular registry of the Pathology Branch of the National Heart, Lung, and Blood