The Role of Patent Foramen Ovale in Cryptogenic Stroke Kriptojenik İnmede Patent Foramen Ovalenin Rolü

INTRODUCTION Approximately 40% of ischemic strokes with no clearly definable etiology are classified as cryptogenic stroke (1). The etiology of some cryptogenic strokes may be an embolus from the venous system traversing from the right to left atrium into the systemic circulation through a patent foramen ovale (PFO), a phenomenon known as paradoxical embolism (2). The first description regarding the association of PFO with stroke was in a young woman with cerebral arterial embolism by Cohnheim et al. (3) in 1877. At autopsy series of general population, the prevalence of PFO is 20−26% (4). However, PFO prevalence in cryptogenic strokes changes between 40% and 55.7% (5). A PFO located between the septum primum and septum secundum leads to the passage of fetal blood from the right atrium to the left atrium. In 75% of PFO cases, thi