Asymmetric septal hypertrophy and hypertrophic cardiomyopathy

Cardiac left ventricular myocardial tissue density, evaluated by computed tomography and autopsy

BACKGROUND

Left ventricular mass (LVM) is an independent risk factor for the prediction of cardiac events. Its assessment is a clinically important diagnostic procedure in cardiology and may be performed by Computed Tomography (CT). The aim of this study was to assess the correlation between the cardiac left ventricular shell volume (LVShV) determined by postmortem Computed Tomography (PMCT) and the anatomic LVM obtained at autopsy and to calculate the myocardial tissue density.

METHODS

A total of 109 deceased individuals were examined with a 64-slice CT scanner and LVShV was determined. At autopsy, the left ventricle was dissected and weighted. The correlation between LVShV and the anatomic LVM was analysed. Asymmetric left ventricular (LV) hypertrophy was recorded. Inter-observer variability was evaluated, and a density value for myocardial tissue was calculated.

RESULTS

The mean age of the deceased was 55 ± 16 years, and 58% was men. We found 30 cases of asymmetric LV hypertrophy. A highly positive correlation existed between LVShV and anatomic LVM (r = 0.857; p < 0.0001), regardless of hypertrophy, asymmetric hypertrophy and gender. The mean difference in the inter-observer variability for LVShV assessment was - 4.4 ml (95% CI: -26.4; 17.6). A linear regression analysis was performed, resulting in a value of 1.265 g/ml for myocardial tissue density. Applying the hitherto used myocardial tissue density of 1.055 g/ml underestimated the anatomic LVM by 18.1% (p < 0.0001).

CONCLUSION

PMCT is a helpful tool for the assessment of LVM, and LVShV is highly correlated with LVM as assessed by subsequent autopsy. The correlation between the two was independent of gender, hypertrophy and LV asymmetric hypertrophy. We found a higher myocardial tissue density of 1.265 g/ml compared to previous studies. We show that PMCT combined with autopsy may contribute not only to anatomical but also clinical knowledge.

Contractile protein mutations and heart disease

Mutations in several muscle structural proteins (the myosin heavy chain, alpha tropomyosin, cardiac troponin T and myosin binding protein C) result in a genetically dominant heart disease, hypertrophic cardiomyopathy. Biochemical data from studies of mutant myosin suggest a dominant-negative mechanism for inheritance of this disease. The most likely primary defect is sarcomere dysfunction, which is followed by the major clinical symptoms.

Electrocardiographic changes can precede the development of myocardial hypertrophy in the setting of hypertrophic cardiomyopathy

A comparison was made of electrocardiographic findings in 107 first-degree relatives of patients with hypertrophic cardiomyopathy without any clinical and echocardiographic signs of the disease and 188 healthy persons with a negative family history. A significantly larger number of electrocardiographic signs of left ventricular hypertrophy (P less than 0.05) and abnormal Q wave (P less than 0.005) was shown in the group of the relatives. Abnormalities of the R wave in V1-3 and of the ST-T segment were also more frequent in this group, but the difference is not statistically significant. In all, electrocardiographic abnormalities were found in 13 of 107 asymptomatic relatives of the patients with hypertrophic cardiomyopathy. These relatives had normal clinical and echocardiographic findings. These 13 patients underwent long-term follow-up (4.5-8 years). Typical hypertrophic cardiomyopathy developed in two patients (an increase in the myocardial thickness from 6 to 15 m in six years and from 8 to 13 mm in 4.5 years, respectively) which was accompanied by progression of the electrocardiographic findings. Electrocardiography is the only commonly available method which may reveal the latent forms of hypertrophic cardiomyopathy at the stage when neither myocardial hypertrophy nor other signs of the disease are expressed. Longitudinal follow-up is necessary for all the relatives of the patients with hypertrophic cardiomyopathy who have abnormal or borderline electrocardiographic findings. A normal echocardiogram cannot exclude the disease at this stage.

Linkage studies of HLA and rheumatoid arthritis in multicase families

The linkage of rheumatoid arthritis (RA) to the HLA-DR locus was investigated in 17 families with multiple cases of RA. Log odds scores were computed using the Liped program; sibship associations were examined by 2 methods. The results showed a trend toward linkage which was short of significance. The results were similar for patients with classic or definite RA, with or without the inclusion of probable RA patients. The finding of strong association and weak linkage would suggest that it is DR4, itself, that is important in RA.

Human lymphocyte antigens in hypertrophic cardiomyopathy

An increasing number of genetic studies in hypertrophic cardiomyopathy challenge conventional views on inheritance and suggest genetic heterogeneity or non-genetic disease. We have found changes in relative risk for some antigens with significantly increased frequency of HLA antigen DR4 in this condition. These findings are consistent with there being a genetic component in susceptibility to hypertrophic cardiomyopathy. No evidence was found for HLA linkage using either sib pair analysis or lod scores. This suggests that hypertrophic cardiomyopathy does not have a disease susceptibility gene related to the HLA region on the short arm of chromosome number six. Population HLA associations with hypertrophic cardiomyopathy must thus be explained by other influences of the genetic background on disease susceptibility.

Prenatal ultrasonic diagnosis of familial asymmetric septal hypertrophy

Hypertrophic cardiomyopathy usually manifests clinically in the second or third decade of life. Two dimensional echocardiography is a reliable indicator of the presence of the disease. This technique is of use in the screening of fetuses at risk for familial cardiomyopathy. This report describes the prenatal echocardiographic detection of hypertrophic cardiomyopathy in the fetus of a mother with hypertrophic cardiomyopathy localized to the apical region of the left ventricle.

Hypertrophic cardiomyopathy in three generations of a large Norwegian family. A clinical, echocardiographic, and genetic study

Hypertrophic cardiomyopathy is a heart muscle disease with an obscure aetiology. Data from four generations of a large family (71 members) are presented. The occurrence of hypertrophic cardiomyopathy among members of the two oldest generations was compatible with a pattern of autosomal dominant inheritance. Seven out of 14 siblings in the second generation had definite signs of or were clinically suspected of having hypertrophic cardiomyopathy. The severity and distribution of left ventricular hypertrophy varied, but three (21%) brothers in generation II showed the classic picture of left ventricular outflow obstruction. Four siblings (29%) died suddenly aged 11, 22, 38, and 40 years. A high incidence of the disease would have been expected in the two younger generations (41 members, aged 1-31 years), but only two, a 16 year old boy and a 17 year old girl had signs of asymmetric septal hypertrophy. Current diagnostic procedures, including M mode and cross sectional echocardiography, are not sufficiently sensitive to identify young family members who may have preclinical hypertrophic cardiomyopathy. No evidence for close genetic linkage between a postulated locus for hypertrophic cardiomyopathy and the major histocompatibility complex (antigens HLA-A, HLA-B, and HLA-DR) was found.

Progression of hypertrophic cardiomyopathy. A cross sectional echocardiographic study

The progression of hypertrophy was studied in 39 patients with hypertrophic cardiomyopathy by echocardiography at follow up from January 1979 to September 1983 (mean follow up 42 months). Thirty two patients were treated medically and 11 had had a septal myotomy-myectomy. Progression of the hypertrophy was noted in four patients treated with propranolol. An additional region in the left ventricular long axis plane was affected in two, extending to the apical region in one and to the basal region in the other, and an additional segment in the left ventricular short axis plane in two extending from the septum into the free wall. The electrocardiograms of these four patients showed a significant increase in QRS voltages (Sokolow-Lyon index increase greater than 10 mm) and of the Romhilt-Estes score (increase greater than or equal to 3 points) in two, development of a left bundle branch block in one, and no change in one. Progression of hypertrophy was seen in none of the 11 patients treated with myotomy-myectomy. Thus echocardiography accurately detects the progression of hypertrophy in patients with hypertrophic cardiomyopathy, which may be prevented by septal myotomy-myectomy.

Genetic heterogeneity of hypertrophic cardiomyopathy

We studied the pattern of inheritance of hypertrophic cardiomyopathy among 111 first-degree relatives of 30 patients with the disease. Results of segregation analysis suggest a genetic heterogeneity for hypertrophic cardiomyopathy in that both autosomal dominant and autosomal recessive mode of inheritance can occur.

The cardiomyopathies: a review of terminology, pathology and pathogenesis

A classification of the cardiomyopathies based on functional and morphological features is outlined, a detailed account of the pathology of each type is presented and possible pathogenetic mechanisms are reviewed. Myocarditis and its relationship to cardiomyopathy is considered and the main morphological and aetiological factors are presented.