Many vascular diseases affect both the heart and the brain. Cardiac diseases often lead to lesions and dysfunction within the brain, and central nervous system (CNS) diseases can influence the heart and its function.
Stroke is a common and devastating disease, the third leading cause of death and the leading cause of disability in the United States. Cardiogenic stroke can occur when (1) the heart pumps unwanted materials into the circulation that reach the brain (embolism), (2) pump function fails and the brain is hypoperfused, and (3) drugs given to treat cardiac disease have neurologic adverse effects.
Direct Cardiogenic Brain Embolism
Cardiogenic cerebral embolism is responsible for approximately 20% of ischemic strokes.1-5 However, because many patients have coexisting cardiac and extracranial vascular disease,5 criteria for the diagnosis of cardiac embolism remain controversial even today. As more advanced diagnostic techniques have been developed, more causative cardiac abnormalities (and their association with stroke) have been recognized. Cardiac sources of brain emboli can be divided into three groups6:
Cardiac wall and chamber abnormalities: cardiomyopathies, hypokinetic and akinetic ventricular regions after myocardial infarction (MI), atrial septal aneurysms, ventricular aneurysms, atrial myxomas, papillary fibroelastomas and other tumors, septal defects, and patent foramen ovale
Valve disorders: rheumatic mitral and aortic disease, prosthetic valves, bacterial endocarditis, fibrous and fibrinous endocardial lesions, mitral valve prolapse, and mitral annulus calcification
Arrhythmias: especially atrial fibrillation (AF) and sick sinus syndrome
Some cardiac sources have much higher rates of initial and recurrent embolism. The Stroke Data Bank7 divided potential sources into strong sources (prosthetic valves, AF, sick sinus syndrome, ventricular aneurysm, akinetic segments, mural thrombi, cardiomyopathy, and diffuse ventricular hypokinesia) and weak sources (myocardial infarct >6 months old, aortic and mitral stenosis and regurgitation, congestive failure, mitral valve prolapse, mitral annulus calcification, and hypokinetic ventricular segments). The risk of embolism varies within individual cardiac abnormalities depending on many factors. For example, in patients with AF, associated heart disease, patient age, duration, chronic versus intermittent fibrillation, and atrial size all influence embolic risk. The presence of a potential cardiac source of embolism does not mean that a stroke was caused by an embolus from the heart. Coexistent occlusive cerebrovascular disease is common. In the Lausanne Stroke Registry, among patients with potential cardiac embolic sources, 11% of patients had severe cervicocranial vascular occlusive disease (>75% stenosis), and 40% had mild to moderate stenosis proximal to brain infarcts.5
Persistent and paroxysmal AF is a potent predictor of first and recurrent stroke, with >75,000 attributed cases annually. In patients with brain emboli caused by a cardiac source, there is a history of nonvalvular AF in roughly one half of all cases, of left ventricular thrombus in almost one third, and of valvular heart disease in one fourth.1,8 Stroke prevention in patients ...