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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

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

Conditions
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Hypoxia, Myocardial Ischemia

Intervention / Treatment
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* Procedure: Continued ventilation
* Procedure: Discontinued ventilation


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Control group<br>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 | Procedure: Discontinued ventilation<br>* Ventilation is discontinued after going on CPB and lungs are exposed to atmospheric pressure<br>|
| Experimental: Ventilation group<br>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 | Procedure: Continued ventilation<br>* 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.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The detection of myocardial ischemia using Cardiac Troponin T (cTn-T) | 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. | Until 72 hours after clamping the aorta | 
| The detection of myocardial ischemia using Heart-type Fatty Acid Binding Protein (hFABP) | 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. | Until 5 hours after clamping the aorta | 
| The detection of myocardial ischemia using Creatine Kinase Myocardial Band (CK-MB) | 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. | Until 48 hours after clamping the aorta | 
| The detection of myocardial ischemia using Reactive Oxygen Species (ROS) | 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. | Until unclamping the aorta (on average until 64 minutes after clamping the aorta) | 
| The occurence of hypoxemia using blood gas measurement | If the partial pressure of oxygen (PaO2) is lower than 60 mmHg, then hypoxemia is present. | Until the end of surgery (on average until 203 minutes after the start of the surgery) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cardiac surgery, Ventilation