In this phase 2, single center, randomized clinical pilot trial, investigators will study the effect of a strategy involving a reduction of beta receptor (BR) stimulation (by decreasing dobutamine dosages) and subsequent BR inhibition (through ultra-short acting betablockers), versus a (routine) strategy with continued BR stimulation through dobutamine infusion, on heart rate in patients with cardiogenic shock due to left- or bi-ventricular failure being supported by V-A ECMO.