Myocardial Strain Analysis in Anaesthetized Coronary Artery Disease Patients During Hyperoxia and Normoxaemia

Not Applicable

Completed

Brief Summary: The purpose of this study is to investigate the impact of supraphysiologic oxygen (hyperoxia) on myocardial function in anaesthetized patients with coronary artery disease.

Detailed Description: Up to 106 patients with coronary artery disease undergoing elective coronary artery bypass graft (CABG) surgery will be recruited to undergo this single visit study. In the timeframe shortly after the induction of anaesthesia and prior to the start of surgery, myocardial strain as a marker of cardiac function will be measured by transesophageal echocardiography (TEE). Echocardiography measurements will be acquired at two different oxygen states for each patient. The fraction of inspired oxygen (FiO2) will be adjusted to reach a normoxaemic state (FiO2=0.3) and a hyperoxic state (FiO2=0.8). Patients will be randomized to which oxygen level is investigated first. Thereafter, the study intervention is completed and anaesthesia and surgery will be performed as planned by the treating team. Echocardiography images will be analyzed in a blinded manner for cardiac function and systolic and diastolic strain parameters. The results will help anaesthesiologists to better weigh risks and benefits when selecting an inspired oxygen fraction in such patients, and will help to evaluate hyperoxia as a risk factor for myocardial injury.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Absolute contraindication for TEE
Emergency surgery, including but not limited to patients with instable CAD: ST- and Non-ST-elevation myocardial infarction (STEMI, NSTEMI) and instable angina (instable AP)
Atrial fibrillation or significant arrhythmia
Pacemaker, CRT, left bundle branch block
Severe-grade valvular disease
Pericardial disease
Previous cardiac or thoracic aortic surgery
Previous chest radiation therapy or cardiotoxic or bleomycin chemotherapy
Severe pulmonary hypertension, cor-pulmonale, or right ventricular dysfunction, i.e., where high FIO2 might reduce pulmonary vascular resistance and right ventricular afterload
Patients where study explanation and informed consent cannot been performed/obtained at the latest on the day before scheduled surgery
Females of child-bearing potential

Arm && Interventions

Group	Intervention	Description
Normoxaemia First	Oxygen	Patients will undergo TEE imaging at normoxaemia (FiO2=0.3) first, and hyperoxia (FiO2=0.8) will be targeted second.
Hyperoxia First	Oxygen	Patients will undergo TEE imaging at hyperoxia (FiO2=0.8) first, and normoxaemia (FiO2=0.3) will be targeted second.

Primary Outcome Measures

Name	Time	Method
Difference in myocardial peak strain between oxygen levels	Through study completion, within 1hour post-induction	Percent (%), a measure of systolic function (shortening and thickening) of the myocardium

Secondary Outcome Measures

Name	Time	Method
Difference in peak twist	Through study completion, within 1hour post-induction	Degrees (°)
Difference in peak torsion	Through study completion, within 1hour post-induction	Degrees/centimeter (°/cm)
Difference in myocardial time to peak strain between oxygen levels	Through study completion, within 1hour post-induction	Milliseconds (ms)
Difference in myocardial strain rate between oxygen levels	Through study completion, within 1hour post-induction	Change in strain over time (/second)
Difference in myocardial strain rate ratio between oxygen levels	Through study completion, within 1hour post-induction	Change in E/A ratio
Difference in myocardial displacement between oxygen levels	Through study completion, within 1hour post-induction	Millimeters (mm)
Difference in myocardial time to peak displacement between oxygen levels	Through study completion, within 1hour post-induction	Milliseconds (ms)
Difference in myocardial velocities between oxygen levels	Through study completion, within 1hour post-induction	Change in displacement over time (millimeters/second)
Difference in myocardial velocity ratio between oxygen levels	Through study completion, within 1hour post-induction	Change in E/A ratio
Difference in ejection fraction (EF)	Through study completion, within 1hour post-induction	Percent (%)
Difference in chamber volumes	Through study completion, within 1hour post-induction	Millilitres (ml)