we use it preoperatively for patients with poor L function as an overnight drip. Preferably, you should give it 24hrs time prior to any surgery. Note that the patient doesn not have to be in an ICU for that therapy.
I know from other centers in Germany that they use it intraoperatively but cannot comment on it due to lack of own experience.
However, we often use it postoperatively in the ICU and replace the PDE-inhibitor with levosimendan several hours after arrival from the OR. Do not combine PDE-Inhibitors with levosimendan. The effecets can be profound.
Our cardiologists also use it in patients with cardiogenic shock who are treated with temporary mechanical support, i.e. ECMO or Impella and have good recovery of LV function in some cases.