Refractory hypoxia in right ventricular infarction.

Dear Editor, Acute myocardial infarction (MI) involving the right ventricle is a rare event.1 Right ventricular myocardial infarction (RVMI) is associated with infarction of the inferior wall of the left ventricle, occurring in more than one third of such cases.1-3 Patent foramen ovale (PFO) is an anatomic inter-atrial communication with the potential risk for shunting of blood. This usually closes within weeks to months after birth but in approximately 27% of adults, shunting through the PFO occurs. This defect is usually of no clinical consequence. However in the setting of right ventricular failure, high right ventricular diastolic pressure can cause a right-to-left shunting via the PFO, resulting in systemic hypoxaemia refractory to supplemental oxygen. Here, we present a case of acute inferior myocardial infarction, complicated by refractory hypoxaemia due to the development of an acute right-to-left inter-atrial shunt through a previously dormant PFO.