Introduction: We have previously shown that primary survival after cardiac arrest (CA) can be improved by optimizing circulation during CPR using a minimal invasive left ventricular assist device (Impella 2.5, iCPR). Whether calculated flow values derived from the Impella Controller during CA are reliable is unknown. Hypothesis: iCPR provides a preservation of right (RV) and left ventricular (LV) function following CA. The transpulmonary flow (TPF) inferred by pulsed-wave Doppler (PWD) during iCPR correlates well with the calculated blood-flow derived from the LVAD controller Methods: Ventricular fibrillation (VF) was electrically induced in 5 anesthetized pigs. Animals were left untreated for 10 minutes before iCPR was attempted. In addition to invasive hemodynamic monitoring, all animals received transesophageal echocardiography at baseline, during untreated cardiac arrest, at the initiation of iCPR, 30 minutes, and 5 hours following ROSC. Results: Preservation of systolic biventricular function within the first 5 hours following ROSC was observed in all individuals. All functional parameters almost returned to baseline values: baseline vs. 5hrs after ROSC: global longitudinal strain (GLS): -25±4.3% vs. -20±2.7%; p =0.388; ejection fraction: 64±8.8% vs. 61.32±10.3%, p =0.971;Stroke volume index: 28.32±8.9 vs. 24.71±12.86 mL/m 2 , p =0.545. The unloading of the LV volume was sufficient (LV-end-diastolic volume (mL): baseline, cardiac arrest, 30min after iCPR, 5hrs. after ROSC: 55.38±2.8, 64.7±9.9, 45.69±7.4, 49.46±13.9). PWD derived TPF during VF correlated well with the calculated flow (TPF: 1.8±0.39 L/min, Impella-Flow: 1.7±0.28 L/min., r =0.868, CI: -0.05842 to 0.9912, p =0.056). RV systolic function did not recover within the same time frame as compared to LV: baseline vs. 5 hrs after ROSC: Tricuspid annular systolic velocity: 11.6±1 vs. 8.5±1 cm/s, p =0.005, RV-fractional area shortening: 42±6.2 vs. 33±6.9 %, p =0.006. Conclusion: iCPR during cardiac arrest provided sufficient unloading of the LV as well as protection and preservation of the LV systolic function. The calculated Impella flow during iCPR correlated well with PWD derived TPF. Further studies are required to quantify effects of iCPR on changes in RV function.