An iatrogenic right to left shunt in a patient with acute right heart failure

Abstract

A 70-year-old lady with atrial fibrillation and bleeding tendency had a left atrial appendage occluder insertion 2 months ago. Her echocardiography showed normal left and right heart function and mild tricuspid regurgitation (TR). The occluder was delivered percutaneously, accessing from the femoral vein to reach the right atrium, and by trans-septal puncture to reach left atrial appendage. She presented this time with cardiac tamponade due to device erosion requiring emergency patch repair. She developed bi-ventricular failure after the operation requiring venaarterial extracorporeal membrane oxygenation (VA-ECMO) support. On weaning down the ECMO flow to 2L/min, her oxygen saturation dropped to 90% despite unremarkable chest examination. Echocardiography showed bi-ventricular failure, with left ventricular ejection fraction 15% and tricuspid annular plane systolic excursion of 0.6 cm. There was increased right heart pressure and right heart dilatation resulting in functional severe TR. Transesophageal echocardiography confirmed that eccentric severe TR was directing towards the iatrogenic defect in the atrial septum, resulting in right-to-left shunt (Fig. 1). On weaning down ECMO, blood in the ECMO circulation returned to the failing right ventricle, aggregating the right heart pressure, TR, and thus the shunt and hypoxia. However, this shunt helped to relieve the right heart pressure in acute right-sided heart failure, and this was left unclosed at the expense of tolerable lower oxygenation saturation. To work up for the cause of heart failure, coronary angiography confirmed kinked left anterior descending by the stitches during patch repair. Pulmonary angiography showed no pulmonary embolism. Revision of patch repair was considered high risk and, therefore, percutaneous coronary stenting was performed. Levosimendan infusion was given for 24 hours as a bi-ventricular inotropic agent. The bi-ventricular function gradually improved. The TR and thus the right-to-left shunt decreased. The patient could be weaned off VA-ECMO in 4 days’ time. Intra-cardiac causes of hypoxia are often neglected. Right-to-left shunt after transeptal puncture is not common without concomitant right-sided heart failure [1]. The chance of right-to-left shunt is particularly high in the critically ill due to various causes of acute right-sided heart failure. The