Intermittent atrial level right-to-left shunt with temporary hypoxemia in a patient during support with a left ventricular assist device

We report a 56-year-old male patient developing hypoxemia after surgical re placement of infected valves of a left ventricular assist device (LVAD, Nov acor(TM)) which had supported him during the previous 15 months. Contrast t ransesophageal echocardiography (TEE) revealed an atrial septal defect with intermittent right-to-left shunt across a patent foramen ovale. We postulate that the shunt detected in this patient occurred as a conseque nce of reduced pulmonary vascular compliance due to positive end-expiratory pressure (PEEP) and an increase of mean intrathoracic pressure. Furthermor e, we hypothesize that synchronized LVAD operation exacerbates any potentia l right-to-left shunt due to the profound left Ventricular unloading which occurs during LVAD support. In this first report of a right-to-left shunt from a previously unrecognize d patent foramen ovale in a Novacor(TM) patient, the subsequent transient h ypoxemia could be managed by avoiding PEEP of more than 3 mmHg, and mean ai rway pressure of more than 11 mmHg and by careful volume replacement in ord er to prevent the pump from completely emptying the left ventricle (LV) and the left atrium (LA). Thus, prior to every LVAD implantation a transesopha geal contrast echocardiography with Valsalva maneuver should be performed t o identify intracardiac right-to-left shunt.