Mural thrombosis of the left atrium following replacement of the mitral valve
Insights
Postoperative mural thrombosis of the left atrium is common after mitral valve replacement. This thrombosis, particularly on the septal and posterior walls, can lead to systemic embolism and prosthesis obstruction.
Area of Science:
- Cardiovascular Surgery
- Pathology
- Thrombosis Research
Background:
- Mural thrombosis in the left atrium is a known complication following mitral valve prosthesis implantation.
- The specific incidence and characteristics of thrombosis on the septal and posterior walls require further investigation.
Purpose of the Study:
- To investigate the incidence and nature of postoperative mural thrombosis on the septal and/or posterior walls of the left atrium.
- To correlate thrombosis with postoperative time and assess the risk of systemic embolism.
Main Methods:
- Autopsy examination of hearts from patients who underwent mitral valve replacement.
- Classification of cases into two groups based on postoperative duration (1-60 days and 61+ days).
- Gross and histological examination of left atrial walls for thrombus presence and organization.
Main Results:
- Mural thrombosis was observed in 61% of patients within 60 days (Group I) and 64% beyond 60 days (Group II).
- Systemic embolism occurred in 43% of Group I and 29% of Group II cases with localized left-sided thrombi.
- Prosthesis obstruction by thrombosis was noted in one instance.
Conclusions:
- Postoperative mural thrombosis of the left atrial septal and posterior walls is a frequent occurrence after mitral valve replacement.
- This thrombosis poses a significant risk for systemic embolism and potential prosthesis dysfunction.
- Operative trauma to these atrial walls may be a contributing factor to thrombus formation.
Abstract:
The nature and incidence of postoperative mural thrombosis of the septal and/or posterior walls of the left atrium were studied in autopsy specimens of hearts from patients in whom the mitral valve had been replaced by a prosthesis 1 day or longer before death. The cases were divided into length of postoperative period as follows; Group I, 1 to 60 days, 57 cases; Group II, 61 days or longer, 36 cases. In Group I mural thrombus of the septal and/or posterior walls of the left atrium was found in 35 of 57 patients (61%). Thrombi against the septal wall tended to be broad and flat. Thrombi involving the posterior wall tended to be multifocal. In Group II, lesions interpreted as old thrombi of the atrial septum were found in 23 of 36 subjects (64%). Grossly, the old lesions were represented by gray nodularity. Histologically such lesions were consistent with organized thrombi. Superimposed recent thrombosis occurred in some cases. Systemic embolism occurred in each group. In the cases in which left-sided thrombi were restricted to the septal and/or posterior walls of the left atrium, systemic embolism was observed in 10 of 23 cases in Group I (43%) and in two of seven cases in Group II (29%). Obstruction of the mitral prosthesis by bulky mural thrombosis originating at the septal wall of the left atrium was observed in one case. The study suggests that the process of postoperative mural thrombosis of the septal and posterior walls of the left atrium may result from trauma to these structures during the operative procedure.
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