Chapter 5 Cardioembolic Stroke

Publisher Summary This chapter discusses the mechanisms and preventive treatment of cardiogenic stroke in selected cardiac conditions. The mechanisms leading to the development of ischemic stroke involves either embolism or hypoperfusion. Cardioembolic stroke occurs when an embolus arising from, or via, the cardiac chambers occludes a cerebral arterial vessel. Endocardial injuries, whether resulting from inflammation or ischemia, expose blood to thrombogenic materials at the endocardial surface. The resulting activation of platelets and the coagulation cascade leads to deposition of fibrin and formation of thrombus. The thrombus may become fragmented and give rise to free-floating emboli. In most patients, an obvious intracardiac thrombus cannot be demonstrated, but embolism is inferred because of a cardiac condition often associated either with embolism or because of a typical neuroimaging appearance of embolic infarction. Anatomical and physiological changes promote thrombosis with formation of microthrombi that embolize distally. Paradoxical embolism is another mechanism of cardioembolic stroke. For this to occur, three conditions must be present: a thrombus in the venous system, a potential connection between the right- and left-sided cardiac chambers, and a right-to-left flow across the connection.