The aim of this study is to compare the effect of warm blood cardioplegia administration with and without roller pump on perioperative myocardial injury, reflected by postoperative biomarker release, in patients undergoing coronary artery bypass grafting (CABG) with a minimal extracorporeal circuit (MECC).

Patients Sixty-eight patients undergoing elective coronary bypass surgery with a MECC system were consecutively enrolled and randomized into a no pump group (blood cardioplegia administration without roller pump) or pump group (blood cardioplegia administration with roller pump). Exclusion criteria were: previous cardiac surgery, scheduled surgery with less than 3 distal anastomoses, left ventricular ejection fraction <45%, chronic renal failure (defined by preoperative creatinine >177 µmol/L) and aortic insufficiency ≥ grade 1. The medical ethics committee of the St. Antonius Hospital approved this study and written informed consent was obtained for each patient prior to the surgical procedure.

Administration of blood cardioplegia In all patients warm blood cardioplegia was administered via the aortic root immediately after aortic cross-clamping. Warm blood cardioplegia consisted of oxygenated blood with added Potassium Chloride/Magnesium Sulphate (KCl/Mg SO4; Pharmacy Catharina Hospital, Eindhoven, The Netherlands: K+ 1.7 mmol/mL, Cl- 1.7 mmol/mL, Mg2+ 0.17 mmol/mL en SO4- 0.17 mmol/mL). An infusion pump was used for the addition of KCl/Mg SO4. Dosage was based on a blood cardioplegia flow of 200 mL/min and adjusted according to the following protocol: the initial dose of KCl/MgSO4 was 5.7 mmol/min (= 6.7 mL), the second dose was 3.4 mmol/min (= 4 mL) and subsequent doses were 2.6 mmol/min (= 3 mL). Each dose was given over a period of 2 minutes. Every 15 minutes the administration of blood cardioplegia was repeated. In case of recurring ECG activity, blood cardioplegia was given with aberrant intervals.

In the no pump group blood cardioplegia was delivered using the arterial line pressure, created by the arterial centrifugal pump of the cardiopulmonary bypass system. Blood cardioplegia flow depended on the difference between arterial line pressure and aortic root pressure. In the pump group blood cardioplegia was delivered using a roller pump. The blood cardioplegia flow was given at 200 mL/min.

Blood sample collection and analyses Blood was collected in EDTA tubes (6 mL) at baseline after induction of anaesthesia (T0), after arrival at the ICU (T1), 4 hours in ICU (T2) and at the first postoperative day (T3). Blood samples were fractionated by centrifuging 1500-2000 x g for 15 min. Plasma was collected and stored at -80°C until analysis. The following biomarkers were analysed: Troponin T high sensitive (TnT-hs), Heart-type Fatty Acid Binding Protein (H-FABP), N-terminal brain natriuretic peptide (NT-pro-BNP) and C-reactive protein (CRP).

Inclusion Criteria:

• Patients undergoing elective coronary artery bypass grafting
• Scheduled surgery with less than 3 distal anastomoses

Exclusion Criteria:

• Previous cardiac surgery
• Left ventricular ejection fraction <45%
• Chronic renal failure (defined by preoperative creatinine >177 µmol/L)
• Aortic insufficiency ≥ grade 1