Mural thrombi in mice with acute viral myocarditis
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Abstract:
In an investigation of the relationship between mural thrombosis and congestive heart failure (CHF) in acute viral myocarditis, inbred BALB/c mice were inoculated intraperitoneally with the M variant of encephalomyocarditis (EMC) virus and sacrificed on days 7 (n = 33), 10 (n = 35) and 14 (n = 39). Myocarditis was found in 105 of 107 sacrificed mice (98.1%). Myocardial necrosis with cellular infiltration was evident after day 7 and was extensive in the ventricles and atria. In the 105 mice with myocarditis, 17 mice (16.2%) developed CHF after day 10, and 15 mice (14.3%) had thrombi as early as day 7. All thrombi were in the left and/or right atrium. The incidence of thrombi in mice with CHF was higher, but not significantly so, than that in mice without CHF (23.5% vs 12.5%). All 50 control mice had no myocardial lesions or thrombi. This study demonstrates that thrombus formation was not rare in the absence of CHF in the acute stage of viral myocarditis and suggests that clinically acute viral myocarditis has a risk of systemic and/or pulmonary embolism even when resting cardiac function is normal.
Insights
Acute viral myocarditis can cause thrombus formation, even without congestive heart failure (CHF). This suggests a risk of embolism in patients with viral myocarditis, even with normal cardiac function.
Area of Science:
- Cardiology
- Virology
- Pathology
Background:
- Acute viral myocarditis is an inflammation of the heart muscle caused by viral infections.
- Congestive heart failure (CHF) is a common complication of myocarditis.
- Mural thrombosis, or clot formation within the heart's walls, is a known risk factor for embolism.
Purpose of the Study:
- To investigate the relationship between mural thrombosis and congestive heart failure (CHF) in acute viral myocarditis.
- To determine the incidence of thrombus formation in mice with and without CHF during acute viral myocarditis.
- To assess the risk of embolism in acute viral myocarditis.
Main Methods:
- Inbred BALB/c mice were inoculated with the encephalomyocarditis (EMC) virus.
- Mice were sacrificed on days 7, 10, and 14 post-inoculation.
- Histopathological examination was performed to assess myocarditis, necrosis, and thrombus formation.
Main Results:
- Myocarditis was observed in 98.1% of sacrificed mice.
- Thrombi were detected in 14.3% of mice as early as day 7, and 16.2% developed CHF after day 10.
- Thrombus incidence was higher in mice with CHF (23.5%) than without (12.5%), though not significantly.
Conclusions:
- Thrombus formation is not rare in the acute stage of viral myocarditis, even in the absence of CHF.
- Clinically, acute viral myocarditis carries a risk of systemic and/or pulmonary embolism.
- This risk exists even when resting cardiac function appears normal.