Interaction between VA-ECMO and Impella

Excerpt

A 60-year old man developed cardiogenic shock after a complicated percutaneous coronary intervention. He initially required 4.0L/min peripheral veno-arterial extracorporeal membrane oxygenation (VA-ECMO) as mechanical circulatory support. An Impella CP was inserted at the femoral artery in a retrograde manner to reach the left ventricle by crossing the aortic valve under fluoroscopic guidance. It served to vent the left ventricle by drawing blood from it foward to the descending aorta. It was set at at slow revolution of P2 to achieve 1L/min forward flow, which was enough for left ventricular venting. His heart function gradually improved and we planned to step up the Impella support and wean off VA-ECMO. However, the patient developed recurrent ventricular tachycardia (VT) when the Impella was stepped up to P8 with 3 L/min flow while maintaining the 4 L/min VA-ECMO flow. Common differential diagnoses included new myocaradial infarction, stent thrombosis and other mechanical complications including ventricular septal rupture, free wall rupture or acute valvular dysfunction. Echocardiography showed none of these findings but that the left ventricle was collapsed, embracing the Impella (video 1 in ESM), and this left ventricular irritation by the Impella resulted in VT. The VA-ECMO flow was immediately decreased to 2L/min and the left ventricle refilled in few seconds (Fig. 1; video 2 in ESM), and the VT stopped.

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