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Pathological substratum for clinical features of fatal myocarditis
1Department of Second Internal Medicine, Fukuoka University School of Medicine, Japan.
Abstract:
Heart autopsies in six cases of fatal myocarditis were examined clinicopathologically. Included were 2 cases in the acute stage, 1 in the subacute stage and 3 in the chronic stage. As to microscopical dating changes, at the acute stage, numerous inflammatory cells were found in the edematous interstitium after 2 days from onset and degeneration, i.e., destruction of myocardial cells without fibrous replacement, was also noted after 11 days. At the subacute stage, irregular patchy and slightly loose fibrosis with inflammatory cells and vascularization was found after 50 days. At the chronic stage, loose fibrosis with inflammatory cells and tight fibrosis without the cells, that is, active and healed myocarditis co-existed. All cases showed heart failure of varying degrees, and also showed, respectively, complete AV block and ventricular fibrillation at the acute stage, and complete AV block and sustained ventricular tachycardia at the chronic stage. In myocarditis, which often was difficult to diagnose clinically, the pathological findings corresponded well to the clinical features retrospectively.
Insights
This study examined fatal myocarditis cases, revealing distinct pathological changes at acute, subacute, and chronic stages. Clinicopathological correlation highlighted how autopsy findings retrospectively explain clinical features of this challenging heart condition.
Area of Science:
- Cardiovascular Pathology
- Myocardial Diseases
- Inflammatory Cardiomyopathies
Background:
- Myocarditis, inflammation of the heart muscle, presents diagnostic challenges.
- Understanding the clinicopathological progression of myocarditis is crucial for patient outcomes.
- This study investigates the histopathological evolution and clinical correlation in fatal myocarditis cases.
Observation:
- Six fatal myocarditis cases were analyzed, categorized into acute (2), subacute (1), and chronic (3) stages.
- Microscopic examination detailed inflammatory cell infiltration, myocardial cell degeneration, and fibrosis development over time.
- Clinical features including heart failure, arrhythmias (AV block, ventricular fibrillation, ventricular tachycardia) were documented.
Findings:
- Acute stage (days 2-11): Edematous interstitium with inflammatory cells, myocardial cell degeneration without fibrosis.
- Subacute stage (approx. 50 days): Patchy, loose fibrosis with inflammation and vascularization.
- Chronic stage: Co-existence of active (loose fibrosis with inflammation) and healed (tight fibrosis without inflammation) myocarditis.
Implications:
- Pathological findings correlate strongly with clinical presentation, aiding retrospective diagnosis.
- The study elucidates the temporal histopathological changes in fatal myocarditis.
- Understanding these changes can improve clinical suspicion and management strategies for myocarditis.