Linear flow during cardiopulmonary bypass (CPB) frequently induces renal damage.

We will evaluate whether automatic intra-aortic balloon pump (IABP) induce pulsatile perfusion preserves renal function in patients undergoing myocardial revascularization at different risk for renal damage.

100 patients undergoing preoperative IABP will be stratified for renal function.

Intervention. The patients will be randomized to non-pulsatile CPB during cardioplegic arrest or automatic IABP induced pulsatile CPB.

Renal function, daily diuretics, complication rate, lactatemia and other biochemical indices will be compared in patients.

We will prospectively enrolle 100 patients undergoing isolated primary high-risk coronary artery bypass grafting for severe left main stem disease (70% narrowing) or left-main equivalent three-vessels coronary disease. On admission to our institution, the patients will be stratified for renal function according to KDOQI and randomly assigned to Group A or Group B. We will exclude from the study patients older than 75 years, and/or with kidney disease ≥ Stage 4 (GFR 15 – 29 ml/min/1.73 m2), and/or with other splanchnic organ comorbidities (liver or mesenteric impairment, abdominal aortic aneurysm, abdominal arteries vasculopathy), and/or severe autoimmune disease.

The patients randomized to Group A (n=50) will receive a preoperative IABP treatment before induction of anesthesia, with IABP turned off during cardioplegic arrest, and restarted with a 1:1 IABP mode immediately after cross-clamp removal (as is the traditionally adopted perioperative IABP support); the other 50 (Group B) will receive standard preoperative treatment with IABP, which will switche into an automatic 80 bpm mode during cross-clamp time, and switche again into a 1:1 IABP after cross-clamp removal, in order to achieve a pulsatile perfusion during the entire intra-operative time-course.

The patients will be stratified in 2 subgroups according to the preoperative renal function: a subgroup will include 64 patients (32 allocated in Group A and 32 in Group B) with stage 1 or 2 [Stage 1: GFR ≥90 ml/min/1.73 m2 – Stage 2: GFR 60 - 89 ml/min/1.73 m2] and therefore considered at lower-risk for post-CPB renal damage; the remaining 36 (18 for each group) with KDOQI Stage 3 of kidney disease (GFR 30 – 59 ml/min/1.73 m2) will be considered at higher-risk for perioperative renal complications [19].