Type 1 cardiorenal syndrome is associated with significant excess morbidity and mortality in patients with severe acute decompensated heart failure. Previous trials of vasoactive drugs and ultrafiltration have not shown superiority over placebo or intravenous diuretics. Pilot data suggest short-term mechanical support devices may support diuresis in the cardiorenal syndrome. We evaluated the intra-aortic balloon pump (IABP) and a novel intra-aortic entrainment pump (IAEP) in a mock circulation loop (MCL) biventricular systolic heart failure model, to assess impact on renal flow and cardiac hemodynamics. Both devices produced similar and only modest increase in renal flow (IABP 3.3% vs. IAEP 4.3%) and cardiac output, with associated reduction in afterload elastance in the MCL. There were minor changes in coronary flow, increase with IABP and minor decrease with IAEP. Differences in device preload and afterload did not impact percentage change in renal flow with IABP therapy, however, there was a trend toward higher percentage flow change with IAEP in response to high baseline renal flow. The IAEP performed best in a smaller aorta and with more superior positioning within the descending aorta. Demonstrated changes in MCL flow during IAEP were of lower magnitude than previous animal studies, possibly due to lack of autoregulation and hormonal responses.