Myocardial dysfunction necessitating inotropic support is a typical complication after on-pump cardiac surgery. This prospective, randomized pilot-study analyses the metabolic and renal effects of the inotropes adrenaline and milrinone in patients needing inotropic support after coronary-artery-bypass-grafting. With respect to data derived from patients with sepsis shock and results from studies using phosphodiesterase-inhibitors prophylactically, the hypothesis is tested that adrenaline may be associated with unwarranted metabolic effects (hyperlactatemia and hyperglycemia) and renal dysfunction.

Following preoperative written informed consent, patients presenting with a cardiac-index (CI) < 2.2 l/min/m2 upon ICU-admission - despite adequate mean arterial (titrated with noradrenaline or sodium-nitroprusside) and filling pressures - will be randomized to 14 hour treatment with adrenaline or milrinone to achieve a CI > 3.0 l/min/m2.

A group of patients not needing inotropes will be used as controls. Hemodynamics, metabolism (plasma lactate, pyruvate, glucose, acid-base status, insulin requirements) and renal function (urinary excretion of alpha-1-microglobulin, creatinine clearance, plasma cystatin-C levels) will be determined during the treatment period and up to 48 hours after surgery (follow up period).

The study is designed as a pilot study including 20 patients per group.

Inclusion Criteria:

• cardiac index below 2.2 l/min/m2 upon intensive care unit admission despite optimized filling pressures and normalized mean arterial blood pressure (MAP) after elective coronary artery bypass grafting

Exclusion Criteria:

• intraoperative use of diuretics or hydroxyethylstarch