association of cryptogenic ischemic stroke and atrial septal aneurysm. a case report

ABSTRACT

Introduction Patent foramen ovale [PFO] is implicated in several pathologic processes including paradoxical embolism in cryptogenic stroke.1 Patients with PFO have significantly higher rates of recurrent cerebral ischemic events than those without PFO.2 Atrial septal abnormalities are associated with embolic events and cryptogenic ischemic stroke in young patients, but the causal link has not yet been established. Paradoxical embolism is considered the most likely mechanism but is rarely proven.3 The role of atrial septal aneurysm [ASA] as a risk factor for cerebral ischemia of unknown etiology is still controversial. Burger et al. have reported that the morphological characteristics of ASA and associated cardiac abnormalities do not distinguish patients at risk for cerebrovascular events.4 The presence of right-to-left shunt [RLS] is essential to allow clot to cross into the left atrium and hence the arterial circulation. In the absence of an identifiable source of embolism, ASA plays an important role as a substrate for clot formation. Consequently, the presence of ASA and RLS are crucial for ischemic stroke to develop and not the mere presence of PFO. Most sources agree that ASA is best detected by transesophageal echocardiography [TEE] while saline agitated contrast enhances the detection of interatrial shunting. The prevalence of ASA in a general referral population of patients was investigated by use of transthoracic echocardiograpy [TTE] and TEE. Contrast TEE was performed to detect interatrial shunting in patients with ASA. In this population, the prevalence of ASA as determined by TTE was 0.47% [24/5079], and 0.78% [40/5079] by TEE. Of these 40 patients, 16 [40%] were judged to be normal by TTE. Of the 40 patients who were positive for ASA, 50% demonstrated interatrial shunting [atrial septal defects, 10; patent foramen ovale, 10]. The authors concluded that TEE is of significant value in detecting the presence of ASA and associated cardiac abnormalities. Contrast TEE further enhances the detection of interatrial shunting in patients with ASA.5 In this paper, we report our experience with a case of young female who developed cryptogenic ischemic stroke. The offending clot was believed to originate from an ASA. The presence of RLS and PFO provided access to the systemic circulation