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Myocardial cell damage during experimental infective endocarditis
Abstract:
Infective endocarditis was induced in 15 catheterized rabbits by a single intravenous injection of Streptococcus viridans and the papillary muscles from the left ventricle were examined for histologic and ultrastructural changes at 3 and 6 days of infection. Papillary muscles from 10 normal and 12 catheterized uninfected animals were used for comparison. Catheterized animals, infected and uninfected, had cardiac hypertrophy and papillary muscles which showed an increase in myofiber size and some interstitial edema. The muscle from infected hearts had areas of focal necrosis, diffuse monocytic infiltration, and loss of normal myocardial architecture. The papillary muscles from catheterized uninfected animals showed some degree of mitochondrial and sarcotubular swelling as well as contracture of myofibrils; the infected myocardium exhibited dramatic changes in ultrastructure such as mitochondrial swelling and destruction, sarcotubular swelling, separation of the intercalated disc, and myofibrillar contracture and disruption. These histopathologic and ultrastructural changes in papillary muscles from rabbits with bacterial endocarditis are indicative of the presence of myocardial cell damage.
Insights
Bacterial endocarditis in rabbits causes significant cardiac damage, including papillary muscle necrosis and ultrastructural changes. These findings highlight the severe impact of infection on myocardial cell integrity.
Area of Science:
- Cardiovascular Pathology
- Infectious Diseases
- Histology and Ultrastructure
Background:
- Infective endocarditis is a serious cardiac infection.
- Catheterization can predispose animals to cardiac complications.
- Understanding endocarditis-induced myocardial damage is crucial.
Purpose of the Study:
- To investigate histologic and ultrastructural changes in rabbit papillary muscles during infective endocarditis.
- To compare infected versus uninfected catheterized and normal control animals.
- To assess the extent of myocardial cell damage.
Main Methods:
- Induction of infective endocarditis in catheterized rabbits using Streptococcus viridans.
- Histologic and ultrastructural examination of left ventricular papillary muscles at 3 and 6 days post-infection.
- Comparison with papillary muscles from normal and uninfected catheterized rabbits.
Main Results:
- Catheterized animals (infected and uninfected) showed cardiac hypertrophy and increased papillary muscle myofiber size with interstitial edema.
- Infected hearts exhibited focal necrosis, monocytic infiltration, and disrupted myocardial architecture.
- Ultrastructural analysis revealed mitochondrial swelling/destruction, sarcotubular swelling, and myofibrillar disruption in infected myocardium.
Conclusions:
- Bacterial endocarditis leads to significant histopathologic and ultrastructural damage in papillary muscles.
- Myocardial cell damage is a key feature of infective endocarditis in this rabbit model.
- These changes indicate severe cardiac compromise due to infection.