Flow-Driven Right-to-Left Shunting Through the Patent Foramen Ovale Causing Hypoxemia and Embolism in a Partial Uhl Anomaly.

BACKGROUND: Uhl anomaly is an exceptionally rare congenital disorder, with fewer than 100 cases reported. In this setting, a patent foramen ovale may become clinically relevant through non-pressure-dependent hemodynamic mechanisms. CASE SUMMARY: A 49-year-old woman presented with progressive dyspnea and a prior ischemic stroke. Multimodality imaging demonstrated diffuse right ventricular myocardial thinning with global systolic dysfunction and torrential functional tricuspid regurgitation, consistent with partial Uhl anomaly. Despite normal right-sided pressures, a permanent right-to-left shunt through the patent foramen ovale was identified, predominantly driven by flow redirection related to severe tricuspid regurgitation. DISCUSSION: In rare conditions such as partial Uhl anomaly, integration of multimodality imaging and invasive hemodynamics is essential to establish the diagnosis and to elucidate unconventional mechanisms underlying clinical events. TAKE-HOME MESSAGES: Partial Uhl anomaly should be considered in adults presenting with unexplained right ventricular dysfunction. Flow-driven right-to-left shunting through a patent foramen ovale may be a major determinant of hypoxemia and embolic risk.