Hypertrophic cardiomyopathy — pathology and pathogenesis

Abstract

Genes on five loci on separate chromosomes are responsible for a familial disease in which all or part of the ventricular muscle undergoes thickening with a histological picture of irregular hypertrophy and disorganized arrangement of myocytes (disarray). The three genes identified so far encode for beta heavy chain myosin (chromosome 14), troponin T (chromosome 1) and alpha tropomyosin (chromosome 15). It is postulated that the phenotype within the heart is produced by abnormal myofibril formation and alignment leading to an abnormal cell shape and, thus, disarray. While all the myocytes carry the gene, the regional selectivity of the hypertrophy is unexplained. The phenotypic expression of the disease within affected members of one family, all of whom are heterozygous for the same gene abnormality, is very varied. Asymptomatic carriers are common, and new mutations do not account for most apparently isolated cases. The phenotypic expression of the disease was studied in 75 hearts. The increase in total heart weight ranged from near normal to over 800 g. Ventricular involvement was diffuse and symmetric in 42%. The commonest asymmetric form involved the anteroseptal region (31%) but sporadic cases involved only the posterior or lateral wall. A minority of cases (9.5%) did not show macroscopic wall thickening. Fibrosis is often associated with dysplastic changes in the media of small intramyocardial arteries and may lead to the ventricular wall simulating a dilated cardiomyopathy. A subaortic patch of endocardial thickening on the ventricular septum due to contact with the anterior cusp of the mitral valve was found in a third of cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and Pathological Impact of Tissue Fibrosis on Lethal Arrhythmic Events in Hypertrophic Cardiomyopathy Patients With Impaired Systolic Function

“…Patients with coexisting valvular diseases responsible for cardiomyopathy were also excluded. 2 A total of 238 patients were clinically diagnosed and pathologically confirmed to have HCM (including 114 HCM with overt LV dysfunction 10 defined as LVEF <50%); 53 patients were excluded because their tissue samples (Masson's staining) had deteriorated over time. Finally, 185 patients (mean age 57±14 years, 62% male) were evaluated.…”

A 45 - year-old woman with hypertrophic cardiomyopathy and cardiogenic shock

“…Nos casos com obstrução da via de saída do VE é comum o achado de espessamentos endocárdicos focais, localizados na cúspide anterior da valva mitral e na via de saída do VE ("imagem em espelho da cúspide anterior"), conseqüen-tes ao atrito produzido pelo choque dessas estruturas durante o movimento anterior sistólico da valva mitral, condicionado pelo elevado gradiente de pressão existente na via de saída do VE 14 .…”

“…Por outro lado, assimetria da hipertrofia esteve presente em 43 (56,7%) casos. Considera-se que o achado anatomopatológico típico, que caracteriza a doença é a presença de desarranjo de cardiomiócitos em extensas áreas do miocárdio 14 .…”

A redução do gradiente na via de saída do ventrículo esquerdo pelo marcapasso DDD em pacientes com miocardiopatia hipertrófica obstrutiva

“…(12) A miocardiopatia hipertrófica obstrutiva (MHO) está caracterizada por uma função sistólica global hiperdinâmica. (13) Embora os parâmetros clínicos da ejeção ventricular esquerda, como a fração de ejeção estejam elevados, a contratilidade ventricular não é necessariamente elevada nessa doença.…”