Percutaneous closure of patent foramen ovale for treatment of hypoxemia: A case series and physiology review.

Intracardiac right-to-left shunt (RTLS) mediated hypoxemia is a rare complication of patent foramen ovale (PFO). The process may be potentiated by reversal of the usual trans-atrial pressure gradient, or from alteration of intracardiac geometry such that venous flow is preferentially directed toward the PFO. We describe a series of four patients who presented with hypoxemia, detailing the diagnostic evaluation which led to the ascertainment of intracardiac RTLS across PFO as the culprit pathology. All underwent successful percutaneous closure with rapid resolution of hypoxemia. Particular attention is given to the underlying anatomic and physiologic derangements facilitating the intracardiac RTLS.