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

BACKGROUND: Most current intracardiac closure devices target the atrial septal defect. However, defects such as the patent foramen ovale (PFO) have unique structural features that may influence rational device design. With mounting interest in transcatheter techniques for closure of PFO in patients with cryptogenic stroke, a clearer understanding of these features is warranted.
METHODS: Retrospectively, we reviewed angiograms obtained at the time of transcatheter closure of PFOs with a non-self-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, mean 9.1 +/- 4.7 mm) bounded by septum secundum and septum primum. The potential 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 defect most commonly appeared as a tunnel-like defect between a thicker, less compliant septum secundum and a thinner, more compliant septum primum. Although the length of the undisturbed tunnel varied widely, the tunnel was shortened or eliminated by placement of a non-self-centering device. The observation that PFO anatomy can be predictably altered by some devices may have an impact on device design or implantation technique.