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Histopathological factors related to diastolic function in myocardial hypertrophy
K Ohsato1, M Shimizu, N Sugihara
1Second Department of Internal Medicine, School of Medicine, Kanazawa University, Ishikawa, Japan.
Insights
Diastolic dysfunction in hypertrophied hearts differs between hypertrophic cardiomyopathy (HCM) and hypertensive asymmetric septal hypertrophy (HT-ASH). Fibrosis impacts HT-ASH, while myocyte disarray impacts HCM, affecting heart diastolic function.
Area of Science:
- Cardiology
- Pathology
- Echocardiography
Background:
- Diastolic dysfunction is a key feature of hypertrophied hearts.
- Understanding the histopathologic basis of diastolic dysfunction is crucial for targeted treatment.
Purpose of the Study:
- To investigate the distinct histopathologic influences on left ventricular diastolic function in hypertrophic cardiomyopathy (HCM) and hypertensive asymmetric septal hypertrophy (HT-ASH).
Main Methods:
- Compared echocardiographic and histopathologic findings in controls, HCM patients, and HT-ASH patients.
- Assessed left ventricular diastolic function using M-mode echocardiography.
- Quantified myocyte diameter, fibrosis, and myocyte disarray from endomyocardial biopsy specimens.
Main Results:
- Both HT-ASH and HCM showed prolonged isovolumic relaxation time and reduced rapid filling volume compared to controls.
- Myocyte diameter and fibrosis percentage did not significantly differ between HT-ASH and HCM.
- Myocyte disarray was significantly greater in HCM than in HT-ASH.
Conclusions:
- Diastolic dysfunction in HT-ASH is primarily linked to myocardial interstitial fibrosis.
- Diastolic dysfunction in HCM is significantly associated with myocyte disarray.
- Histopathologic differences explain distinct mechanisms of diastolic dysfunction in these conditions.
Abstract:
To clarify the histopathologic influence on diastolic function in the hypertrophied heart, we compared the echocardiographic and histopathologic findings in 9 controls, 10 patients with hypertrophic cardiomyopathy (HCM), and 8 hypertensive patients with asymmetric septal hypertrophy (HT-ASH). M-mode echocardiography was used to determine the left ventricular diastolic function. Mean diameter of myocytes, percentage of fibrosis and disarrangement were quantitatively calculated from right ventricular endomyocardial biopsy specimens. In both HT-ASH and HCM, the isovolumic relaxation time was significantly longer and the rapid filling volume tended to be smaller than in the controls. Histopathologically, the mean diameter of myocytes and percentage of myocardial interstitial fibrosis did not differ significantly between HT-ASH and HCM. However, quantitative disarrangement of myocytes in HCM was significantly greater than that in HT-ASH. Multiple regression analysis showed that the percentage of fibrosis was the most significant factor related to diastolic left ventricular dysfunction in HT-ASH, while disarrangement of myocytes was the most significant in HCM. We conclude that diastolic dysfunction in HT-ASH can be attributed to the percentage of fibrosis, and to disarrangement of myocytes in HCM.