Case Report First-in-Man Method Description: Left Ventricular Unloading With iVAC2L During Veno-Arterial Extracorporeal Membrane Oxygenation: From Veno-Arterial Extracorporeal Membrane Oxygenation to ECMELLA to EC-iVAC®

Abstract

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is increasingly used in bi-ventricular failure with cardiogenic shock to maintain systemic perfusion. Nonetheless, it tends to increase left ventricular (LV) afterload and myocardial oxygen demand. In order to mitigate these negative effects on the myocardium, an Impella CP® (3.5 L/min Cardiac Output) can be used in conjunction with V-A ECMO (ECMELLA approach). We implemented this strategy in a patient with severe acute myocarditis complicated by cardiogenic shock. Due to a hemolysis crisis, Impella CP® had to be substituted with PulseCath iVAC2L®, which applies pulsatile flow to unload the LV. A subsequent improvement in LV systolic function was noted, with increased LV ejection fraction (LVEF), LV end-diastolic diameter (LVEDD) reduction, and a reduction in plasma free hemoglobin. This case documents the efficacy of iVAC2L in replacing Impella CP as a LV vent during V-A ECMO, with less hemolysis.

Keywords: ECMO; IVAC; Impella; heart failure; mechanical circulatory support; mechanical unloading.

Figure 1

Histology (A) as well as immunohistological findings (B) in left ventricular endomyocardial biopsies illustrate a severe lymphocytic myocarditis with myocyte necrosis (blue circles) and infiltration of invading inflammatory cells (brown infiltrates).

Figure 2

(A) IABP console during LV unloading with V-A-ECMO and iVAC2L. The diastolic pressure drop in the aortic pressure (green arrows) is attenuated as pressure increases in the gas chamber of iVAC2L (bottom waveform in blue). LV blood aspirated during systole is then ejected back in the ascending aorta. When the pressure falls in the gas chamber, ejection stops and aortic pressure quickly drops. The magnitude of the attenuation in the pressure drop may oscillate between successive beats due to transitory variations in myocardial conduction, mechanics and loading conditions generated by extra-systoles, arrhythmias or changes in intrathoracic pressure. (B) Aortography showing a watershed line around the left subclavian artery during 3.5 L/min V-A ECMO. (C) In the 5^th heart beat following iVAC2L activation, the watershed line moved to the descending aorta demonstrating a decrease in afterload despite V-A ECMO support. Red circle: two-way valve (outlet) positioned next to the coronary ostia; red arrow: distal tip if the iVAC system in the left ventricle; green arrow: pigtail catheter.

Figure 3

(A) Illustration of iVAC2L positioned inside the left ventricle. Blood is aspirated through the inlet to the membrane pump during systole and ejected in the ascending aorta through the proximally located outlet valve. (B) Technical details of iVAC2L including the bi-directional catheter and the membrane pump.