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[Morphological characteristics of the left ventricle with volume-and pressure-overload in valvular heart diseases]
J Fukuda1, T Yoshimura, J Hayashi
1Second Department of Surgery, Niigata University School of Medicine, Japan.
Insights
Advanced left ventricular hypertrophy can impair pump function post-surgery due to irreversible myocardial damage. Histopathological changes, including fibrosis, correlate with poor outcomes in these patients.
Area of Science:
- Cardiovascular Pathology
- Cardiac Surgery
- Histopathology
Context:
- Persistent left ventricular (LV) pump dysfunction after cardiac surgery, particularly in advanced hypertrophy, suggests irreversible myocardial damage.
- Understanding the histopathological basis of impaired LV function in hypertrophied hearts is crucial for predicting surgical outcomes.
Purpose:
- To investigate the histopathological changes in the left ventricular muscle of patients with hypertrophied hearts, focusing on myocardial hypertrophy and fibrosis.
- To correlate these histological findings with pre-operative and post-operative cardiac function and dimensions.
Summary:
- In volume-overloaded hearts (AR, MR), muscle cell diameter correlated with LV dimensions and volume indices, while fibrosis correlated with LV volume index.
- Massive myocardial hypertrophy (cell diameter >30 microns) with severe fibrosis was associated with persistent LV dilatation and poor post-operative function in some patients.
- In pressure-overloaded hearts (AS), muscle cell diameter correlated with LV wall thickness and end-systolic volume index, with less pronounced fibrosis compared to advanced hypertrophy.
Impact:
- Identifies specific histopathological markers (massive hypertrophy, severe fibrosis) and dimensional thresholds (LVDd, LVDs, LVEDVI, LVESVI) predictive of poor post-operative cardiac function.
- Provides insights into the mechanisms of persistent LV dysfunction after corrective surgery for valvular heart disease.
- Highlights the importance of assessing myocardial tissue characteristics beyond simple chamber dilation in hypertrophied hearts.
Abstract:
There are some cases in which pump function of the left ventricle (LV) is not sufficiently improved despite of successful operation, especially in advanced hypertrophy. The impaired pump function is believed to result from irreversible myocardial damage. Thus, the present study is designed to make clear the histopathological changes of the LV muscle in hypertrophied hearts. Fifty-six patients with volume-overloaded hearts (27 with AR, 24 with MR, and 4 with AR and MR) and 10 patients with AS were examined. Cardiac muscle specimens for histological examination were obtained from the LV anterior wall. In volume-overloaded hearts, the muscle cell diameters were correlated with both LV dimension (LVDd and LVDs) and LV volume index (LVEDVI and LVESVI). The progress of interstitial fibrosis was correlated with LV volume index. Five of the 9 patients with massive myocardial hypertrophy (in all cases, muscle cell diameter was greater than 30 microns) did not show any improvement in histological figure after operation and displayed persistent postoperative LV dilatation. Patients with either LVDd greater than 75mm and LVDs greater than 55mm or LVEDVI greater than 200ml/m2 and LVESVI greater than 100ml/m2, whose hearts showed massive myocardial hypertrophy and severe fibrosis, tended to have postoperative cardiac dysfunction. In pressure-overloaded hearts, the muscle cell diameters were correlated with LVPWTh and LVESVI. Noteworthily, fibrosis and degeneration of muscle fibers were slight as compared with advanced myocardial hypertrophy.