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Pathological features of hypertrophic obstructive cardiomyopathy
Insights
Hypertrophic obstructive cardiomyopathy presents varied macroscopic features. A distinctive fibrous band below the aortic valve aids diagnosis, especially in symmetrical hypertrophy cases.
Area of Science:
- Cardiology
- Pathology
- Medical Imaging
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) exhibits diverse macroscopic presentations.
- Left ventricular hypertrophy can be asymmetrical or symmetrical, with varying ventricular volumes.
- Morphological changes can mimic other cardiomyopathies like congestive cardiomyopathy.
Purpose of the Study:
- To describe the variable macroscopic features of hypertrophic obstructive cardiomyopathy.
- To identify characteristic pathological findings aiding HOCM diagnosis.
- To correlate morphological features with clinical presentation and patient demographics.
Main Methods:
- Macroscopic examination of hearts from patients with HOCM.
- Microscopic analysis of cardiac tissue, focusing on endocardial lesions.
- Correlation of pathological findings with cineangiographic data and patient age.
Main Results:
- Asymmetrical left ventricular hypertrophy with small ventricular volume is common.
- Symmetrical hypertrophy and cavity dilatation can occur, resembling congestive cardiomyopathy.
- A distinctive fibrous band below the aortic valve, an endocardial friction lesion, was observed in 18 hearts.
- This band, indicative of systolic contact between mitral cusp and septum, is characteristic of HOCM and aids diagnosis in symmetrical or dilated forms.
- Sudden death was common in younger patients; HOCM was incidental in older patients.
Conclusions:
- Macroscopic features of HOCM are variable, necessitating recognition of diverse presentations.
- The fibrous band below the aortic valve is a key diagnostic marker for HOCM.
- Understanding these morphological features improves diagnostic accuracy, particularly in atypical cases.
Abstract:
The macroscopic features of hypertrophic obstructive cardiomyopathy are variable. The most easily recognized picture is of disproportionate and asymmetrical left ventricular hypertrophy with a small ventricular volume. Symmetrical ventricular hypertrophy also occurs and dilatation of the ventricular cavity may lead to a configuration more usually associated with congestive cardiomyopathy. Papillary muscle involvement leads to a bullet shape, often retained even when the ventricle dilates. Eighteen of the hearts showed a distinctive band of fibrous thickening below the aortic valve. This was a mirror image of the free edge of the anterior mitral cusp, had the microscopic features of an endocardial friction lesion, and was clearly the morphological expression of the systolic contact between cusp and septum seen on cineangiography. This band is characteristic of hypertrophic obstructive cardiomyopathy; it was more common in older patients and is of particular diagnostic value in cases with symmetrical hypertrophy, including those with dilated ventricular cavities. Sudden death was the commonest presentation in the younger cases but in several cases over 60 years at death hypertrophic obstructive cardiomyopathy was an incidental necropsy finding.