Structural and compliant anatomy of the patent foramen ovale in patients undergoing transcatheter closure

Background Most current intracardiac closure devices target the atrial sept al defect. However, defects such as the patent foramen ovale (PFO) have uni que structural features that may influence rational device design. With mou nting interest in trans catheter techniques for closure of PFO in patients with cryptogenic stroke, a clearer understanding of these features is warra nted. Methods Retrospectively, we reviewed angiograms obtained at the time of tra nscatheter closure of PFOs with a nonself centering device in a group of 21 patients with a history of stroke. Results The PFO appeared as a tunnel of varying length (2.4 to 19.5 mm, mea n 9.1 +/- 4.7 mm) bounded by septum secundum and septum primum. The potenti al area of the defect was as small as 12.2 mm(2) and as large as 121.1 mm(2 ). With device placement, the tunnel length shortened or disappeared (0.5 /- 1.6 mm) by inferior displacement of the more compliant septum primum. Conclusions In patients with PFO referred for transcatheter closure, the de fect most commonly appeared as a tunnel-like defect between a thicker, less compliant septum secundum and a thinner, more compliant septum primum. Alt hough the length of the undisturbed tunnel varied widely, the tunnel was sh ortened or eliminated by placement of a non-self-centering device. The obse rvation that PFO anatomy can be predictably altered by some devices may hav e an impact on device design or implantation technique.