Beyond existence: Physiologic phenotyping of patent foramen ovale

Patent foramen ovale (PFO) closure has matured from an anatomic procedure in search of an indication to a guideline-supported therapy for carefully selected adults with PFO-associated ischemic stroke [1].A PFO is common and stroke is common; however, their coexistence is often incidental.Paradoxical embolism requires 3 elements: an upstream venous milieu capable of generating embolic material, a conduit that permits right-to-left vascular passage, and a downstream systemic vascular bed vulnerable to occlusion [2].Without actual right-to-left shunting, venous material cannot plausibly reach the arterial circulation.This mechanistic truth