Anatomy of the patent foramen ovale for the interventionalist

Abstract

Background: Patent foramen ovale (PFO) is an interatrial communication whose management is controversial. Several manufacturers have submitted protocols for Food and Drug Administration (FDA) approval of their PFO closure device. The purpose of this study was to define anatomy relevant to percutaneous PFO closure, validate the clinical observation that most PFOs contain little tissue rim at the aorta, comment on proposed closure guidelines, and to discuss approaches to PFO closure.

Methods: From the Mayo Clinic Tissue Registry, five normal hearts with PFO were selected from each sex from the first 10 decades of life (n = 100). Measurements (mm) included PFO length, diameter, and distance from FO-superior vena cava (SVC) and FO-aortic annulus (AoAn). Patient age, weight, and height were obtained from autopsy reports, and body surface area (BSA) was calculated.

Results: PFO length and diameter increased with age (P = 0.029 and 0.001, respectively), and FO-SVC and FO-AoAn increased with BSA (P <or= 0.0001 and 0.006, respectively). PFO diameter was larger in women than men (P = 0.028). Using current sizing guidelines, 66% (CI = 56-75%) of the 100 patients would have been excluded from device closure, and only 31% could have received the smallest (18 mm) device.

Conclusions: Our results suggest that the proposed device closure guidelines may result in inappropriate device sizing. In addition to excluding suitable candidates, strict application of the guidelines could also result in incomplete closure or device embolization. Suggestions for modification of the guidelines and options for device closure are discussed.