Prior Stroke in PFO Patients Is Associated With Both PFO-Related and -Unrelated Factors

Ignored Role of Paroxysmal Atrial Fibrillation in the Pathophysiology of Cryptogenic Stroke in Patients with Patent Foramen Ovale and Atrial Septal Aneurysm

The association between cryptogenic stroke (CS) and patent foramen ovale (PFO) with or without atrial septal aneurysm (ASA) has been a debate for decades in terms of pathophysiologic processes and clinical courses. This issue has become more interesting and complex, because of the concerns associating the CS with so-called normal variant pathologies of interatrial septum, namely ASA and PFO. While there is an anatomical pathology in the interatrial septum, namely PFO and ASA, the embolic source of stroke is not clearly defined. Moreover, in patients with PFO and CS, the risk of recurrent stroke has also been associated with other PFOunrelated factors, such as hyperlipidemia, body mass index, diabetes mellitus, and hypertension, leading to the difficulty in understanding the pathophysiologic mechanism of CS in patients with PFO and/or ASA. Theoretically, the embolic source of cryptogenic stroke in which PFO and/or ASA has been involved can be categorized into three different anatomical locations, namely PFO tissue and/or ASA tissue itself, right or left atrial chambers, and venous vascular territory distal to the right atrium, i.e., inferior vena cava and lower extremity venous system. However, the possible role of paroxysmal atrial fibrillation associated with PFO and/or ASA as a source of cryptogenic stroke has never been mentioned clearly in the literature. This review aims to explain the association of cryptogenic stroke with PFO and/or ASA in a comprehensive manner, including anatomical, clinical, and mechanistic aspects. The potential role of paroxysmal atrial fibrillation and its contribution to clinical course have been also discussed in a hypothetical manner to elucidate the pathophysiology of CS and support further treatment modalities.

[Thalamic infarction following paradoxical embolism during total hip replacement : Case report and pathophysiological considerations]

Because of a painful right-sided coxarthrosis a 57-year-old female patient underwent a cementless total arthroplasty under general anesthesia. Except for Asperger's syndrome and an occlusion of a vein in her left eye she stated no other diseases or complaints, especially no cardiac problems. Postoperatively she developed neurological symptoms of left-sided hemiparesis and hemihypesthesia. A cranial computer tomography was performed and a right-sided infarction of the thalamic region was found. A patent foramen ovale (PFO) and atrial septal aneurysm were detected 5 days later. The incidence of a PFO is given as 25% of the population. A paradoxical air embolism in the presence of a PFO is a feared complication in neurosurgical interventions in a semi-sitting or sitting position. Corpuscular emboli, such as bone, cement, fat or wound debris may be the reason for paradoxical embolisms in combination especially with partial or total hip replacement. The kind of embolism in the case described could not be clarified. Deep vein thrombosis or cardiac arrhythmia could be excluded. Therefore, it can be considered most likely that the operation site was the source of the embolism. The trigger for a paradoxical embolism is a reversal of the pressure difference between the right and left atria: normally the left atrial pressure exceeds the right atrial pressure by ca. 2-4 mm Hg, resulting possibly in a small clinically irrelevant left-to-right shunt. If the pulmonary arterial circulation is compromised and pulmonary vascular resistance increases, the pressure gradient between the left and right atria reverses and a right-to-left shunt can occur causing a paradoxical embolism. Positive end-expiratory pressure (PEEP) ventilation during anesthesia could be an important reason for a shunt reversal between the right and left atria and therefore favoring a paradoxical embolism but the pathophysiological role of PEEP has not yet been finally clarified.