Intermittent antegrade isotermic blood cardioplegia with and without N-acetylcysteine: a randomized controlled trial

Abstract

This is a randomized prospective investigation whose the purpose is to verify if the addition of N-acetylcysteine (NAC) to a cardioplegic solution improves the myocardial and endothelial protection during on-pump coronary bypass graft surgery. Patients: Thirty adults (> 21 years old) of any gender will be randomly allocated in two groups after informed consent: Control and NAC Group (N-acetylcysteine). Exclusion criteria: patients under 21 years old, off-pump CABG surgery, urgency/emergence operations, pregnancy, history of allergy to NAC, cardiogenic shock, non-treated peptic ulcer, epilepsy, recent myocardial infarction (less than 3 weeks), associated operations. Anesthesia: The anesthesiologists will follow the standard procedures according the anesthesiology service of the HCFMRP-USP. Operations: All operations will be performed using medium sternotomy. The grafts will be chosen according the surgeons discretion and the cardiopulmonary bypass will be conducted according the routines of the cardiopulmonary bypass staff for all patients. The cardioplegic solution will be infused intermittently through the ascending aorta at the maximum interval of 20 min. Cardioplegic solutions a) “Control solution”- 500 ml of arterial blood plus 60 mg of de lidocaine, 10 mEq of KCl and 8 mEq of magnesium sulfate. b) “NAC solution” – it has the same volume and composition of the “control solution” plus 300 mg N-acetylcysteine (fluimucil 300mg/3ml – Zambon Ltda, Brasil). Biochemical analyses: Blood will be collected from the coronary sinus and radial artery catheter to assay of a) malondialdehyde (MDA): 15 minutes and 30 minutes after the aortic cross clamping (reperfusion), b) sVCAM-1: 30 minutes after the aortic cross clamping. C) malondialdehyde (MDA) and sVCAM-1 will be determined at the same intervals from systemic blood, d) Serum troponin I will be determined before sternotomy, 2 h after aortic cross clamping and each 8 h during the next 48 h.. Malondialdehyde assay: It will be performed using spectrophotometry from stored frozen samples (-70 C). Troponin I assay: It will be performed using chemiluminescence. sVCAM-1 assay: It will be performed using ELISA. Perioperative procedures: The perioperative care will be conducted according the routines of the cardiac postoperative intensive care unit. Clinical data will be collected to verify morbidity (acute myocardial infarction, need of mechanical and/or pharmacological cardiovascular support, organ failure, infection, stroke, etc) and mortality for both groups. (AU)