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Etiology and pathogenesis of thromboembolism
1Hebrew Hospital for Chronic Sick, Bronx, NY.
Insights
Blood stasis in the heart chambers can lead to thrombus formation and thromboembolism, especially in patients with atrial fibrillation. Various cardiac conditions increase the risk of stroke from these blood clots.
Area of Science:
- Cardiology
- Hematology
- Vascular Medicine
Background:
- Thrombus formation in the left atrium and ventricle arises from blood stasis, activating the coagulation cascade.
- Thromboembolism occurs when these clots migrate into systemic circulation, driven by circulatory forces.
- Atrial fibrillation is the most frequent cardiac condition predisposing to thromboembolic events.
Purpose of the Study:
- To delineate the diverse cardiac sources and associated risk factors contributing to thromboembolic stroke.
- To categorize the prevalence of different cardiac conditions leading to thromboembolism.
Main Methods:
- Review of existing literature and clinical data on cardiac sources of thromboembolism.
- Analysis of patient cohorts with atrial fibrillation and other cardiac disorders.
- Identification of specific risk factors and their contribution to stroke incidence.
Main Results:
- Non-valvular atrial fibrillation is a major source (45%), linked to ischemic heart disease, hypertension, and cardiomyopathy.
- Other significant contributors include acute myocardial infarction (15%), ventricular aneurysms (10%), rheumatic valvular disease (10%), and prosthetic valves (10%).
- Conditions like mitral valve prolapse, cardiomyopathies, and aortic stenosis also pose thromboembolic risks.
Conclusions:
- Thromboembolism is a multifactorial complication of various cardiac conditions, with atrial fibrillation being paramount.
- Understanding these diverse sources is crucial for targeted prevention and management strategies to reduce stroke risk.
Abstract:
Thrombus formation in the left atrium and left ventricle is primarily due to stasis of blood which causes activation of the coagulation system. Migration of thrombotic material into the circulation depends on the dynamic forces of the circulation. Atrial fibrillation is the commonest underlying cardiac disorder predisposing to thromboembolism. Rheumatic mitral stenosis, left atrial enlargement, prior myocardial infarction, hypertension, and echocardiographic left ventricular hypertrophy are risk factors for thromboembolic stroke in elderly patients with chronic atrial fibrillation. Non-valvular atrial fibrillation accounts for 45% of cardiac sources of thromboembolic stroke and includes patients with ischemic heart disease, hypertension, thyrotoxic heart disease, hypertrophic cardiomyopathy, chronic sinoatrial disorder, and idiopathic atrial fibrillation. 15% of cardiac sources of thromboembolic stroke are associated with acute myocardial infarction, 10% with left ventricular aneurysm and mural thrombi remote from an acute myocardial infarction, 10% with rheumatic valvular heart disease, and 10% with prosthetic cardiac valves. Mitral valve prolapse, mitral annular calcium, nonischemic cardiomyopathies, infective endocarditis, nonbacterial thrombotic endocarditis, left atrial myxoma, paradoxical embolism associated with congenital heart disease, calcific aortic stenosis, and complex atherosclerotic plaque within the proximal aorta also contribute to thromboembolism.