Antithrombotic Therapy for Cerebrovascular Disorders: Paradoxic Embolism and Congenital Heart Disease

Paradoxic Embolism and Congenital Heart Disease
Paradoxic emboli are usually associated with a probe-patent foramen ovale present in 35% of autopsies. They also occur with atrial or ventricular septal defects, patent ductus, and pulmonary arteriovenous fistulas. The clinical diagnosis of paradoxic embolism requires a venous source of emboli, evidence of arterial embolization, and an intracardiac defect or pulmonary arteriovenous fistula. An increase in right atrial pressure, resulting in shunting across a probe-patent foramen ovale, can be due to coexistent major pulmonary embolism or Valsalva maneuvers. Clinically obvious phlebitis is present in about 45% of patients with paradoxic embolism and factors predisposing to phlebitis in about 70%. Contrast echocardiography and color flow Doppler studies can detect physiologic shunting through the foramen ovale. Some series have reported multiple sites of emboli, both cerebral and systemic, with paradoxic emboli. There are no controlled studies addressing therapy, but the success of anticoagulation in venous thrombosis with and without pulmonary embolism suggests that it is likely to be effective in this context. read
Congenital heart disease predisposes to brain embolism by right-to-left shunting of blood with paradoxic embolism, by predisposing to infective endocarditis, and by associated AF.
Atrial Septal Aneurysm
Atrial septal aneurysm is a congenital redundancy of the atrial septum best identified by echocardiography. This rare abnormality has been associated with brain and systemic emboli. It occurred in 0.5% of all echocardiograms done at Duke University and in 2.0% of echocardiograms referred to rule out a cardiac cause for brain ischemia. With echocardiography there is bulging of the interatrial septum, with either protrusion into the right atrium or movement back and forth between the left and right atria. Atrial septal aneurysm is often associated with a right-to-left shunt at the atrium.
Nonischemic Cardiomyopathy
Brain embolism is common in patients with nonischemic cardiomyopathy of almost all types. The common denominator of these cardiomyopathies appears to be a dilated, hypokinetic ventricle, with or without secondary AF, which predisposes to thrombi and subsequent embolism. No controlled studies of antithrombotic therapy are available; however, there is consensus that long-term anticoagulation therapy should be considered even in the absence of echocar-diographically defined thrombus.