Patent Foramen Ovale–Induced Hypoxemia Unmasked During Pregnancy

BACKGROUND: Patent foramen ovale (PFO) is a common finding that occurs in approximately 25% of the population and, in the absence of clinical sequelae, is considered benign. However, PFO can potentially become clinically significant and result in systemic embolization, strokes, or hypoxemia. During pregnancy, hemodynamic cardiovascular changes may unmask previously undetected congenital heart anomalies or exacerbate existing ones, affecting both mother and fetus. CASE SUMMARY: A healthy 33-year-old woman developed symptomatic hypoxemia on minimal exertion during pregnancy secondary to newly diagnosed right-to-left intracardiac shunting through a PFO. We posit that the physiological changes of pregnancy enhanced this abnormal streaming through the PFO without evidence of pulmonary hypertension. The patient had a successful percutaneous occlusion of the PFO with a 25-mm Amplatzer cribriform septal occluder device at 18 weeks' gestation, with appropriate fetal protection. CONCLUSIONS: Pregnancy may produce or accentuate acute hypoxemia due to right-to-left shunting through a PFO. The PFO may be safely treated with percutaneous device closure to resolve hypoxemia-related symptoms and avert risks of hypoxia to the developing fetus.