The Effect of Mechanical Ventilation on the Occurrence of Myocardial Ischemia: a Pilot Study (VENTMICS)

The Effect of Mechanical Ventilation on the Occurrence of Myocardial Ischemia in Patients Undergoing Endoscopic Coronary Artery Bypass Grafting (Endo-CABG): a Pilot Study

The goal of the proposed pilot study is to determine which method can detect myocardial ischemia at the predefined timepoints during endo-CABG. Additionally, the investigators want to examine the influence of mechanical ventilation on the occurrence of myocardial ischemia in patients undergoing endo-CABG.

CABG is the most effective therapy for patients suffering from coronary artery disease, a condition which annually affects 126 million people worldwide. During this surgery, cardiopulmonary bypass (CPB) takes over the function of the heart and lungs. As a result of the emergence of minimally invasive cardiac surgery (MICS) (e.g. endoscopic-CABG), peripheral CPB with femoral arterial cannulation became the most commonly utilized strategy. However, the use of retrograde arterial perfusion is not without risk. It may result in the upper body and coronary arteries being perfused with deoxygenated blood. The hypoxemia will induce myocardial ischemia and this can harm the cardiac myocytes. A solution for this inconvenience is still lacking. Literature reports that establishing adequate ventilation support should help overcome this phenomenon. However, this approach has not yet been investigated in a clinical trial. In general, this phenomenon is not well recognized in the typical surgical setting, and limited research has been done. The goal of the proposed pilot study is to determine which method can detect myocardial ischemia at the predefined timepoints during endo-CABG. Additionally, the investigators want to examine the influence of mechanical ventilation on the occurrence of myocardial ischemia in patients undergoing endo-CABG.

Ventilation is discontinued after going on CPB and lungs are exposed to atmospheric pressure. Blood will be drawn: At baseline: before general anaesthesia After start of heart-lung machine After clamping the aorta Before unclamping the aorta After the operation 5 h after clamping the aorta 12 hours after clamping the aorta 24 hours after aortic clamping 48h after clamping the aorta 72 hours after clamping the aorta

Ventilation is continued from going on CPB until clamping of the ascending aorta. Blood will be drawn: At baseline: before general anaesthesia After start of heart-lung machine After clamping the aorta Before unclamping the aorta After the operation 5 h after clamping the aorta 12 hours after clamping the aorta 24 hours after aortic clamping 48h after clamping the aorta 72 hours after clamping the aorta

Ventilation is continued from going on CPB until clamping of the ascending aorta with tidal volume 3ml/kg ideal body weight, Fraction of inspired oxygen (FiO2) 50%, respiratory rate 5/min and Inspiratory:Expiratory (I/E) ratio 1/2.

If the value of Cardiac Troponin T (cTn-T) exceeds 14 ng/L, then cTn-T is able to detect myocardial ischemia at the predefined time points.

If the value of Heart-type Fatty Acid Binding Protein (hFABP) exceeds 6 ng/L, then hFABP is able to detect myocardial ischemia at the predefined time points.

If the value of Creatine Kinase Myocardial Band (CK-MB) exceeds 6.2 µg/L, then CK-MB is able to detect myocardial ischemia at the predefined time points.

Reactive Oxygen Species (ROS) measurements include a malondialdehyde assay to assess the lipid peroxidation, an Oxystat test to analyse the total peroxide levels and a protein carbonyl assay to assess the protein damage due to cardiomyocyte dysfunction. Additionally a biopsy will be taken to analyze pro- and anti-oxidants. If a significant increase in lipid peroxidation, total peroxide levels, protein damage and/or pro- and anti-oxidants in the ventilation group compared to the control group is present, then ROS is able to detect myocardial ischemia at the predefined time points.

Inclusion Criteria: Age > 18 years old Patients undergoing their first elective endo-CABG procedure Patients capable of signing the informed consent Patients able to speak Dutch or French Exclusion Criteria: Ongoing participation in another trial Ejection fraction < 50% Lung diseases (COPD, asthma) Use of corticosteroids