Intracardiac right-to-left shunting through a patent foramen ovale is a known cause of arterial hypoxemia. We present a case report of a patient supported with a left ventricular assist device who had significant right-to-left shunting as visualized with transesophageal echocardiography. When the device was turned off, no further shunting occurred and arterial hypoxemia resolved. Our report is the first visual representation of the anatomy of a patent foramen ovale in a patient supported with a left ventricular assist device.