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Haemodynamic and EKG changes in patients undergoing minimally invasive direct coronary artery bypass
Anis S Baraka1, Sania Haroun-Bizri, Bassem R Shabb
1Dept. of Anesthesiology, American University of Beirut, P.O. Box: 113-6044, Beirut. abaraka@aub.edu.lb
Insights
Minimally invasive direct coronary artery bypass surgery (MIDCAB) can cause ST segment elevation and arrhythmias. Risk factors for these events include a history of unstable angina or myocardial infarction.
Area of Science:
- Cardiovascular Surgery
- Anesthesiology
- Cardiac Electrophysiology
Background:
- Minimally invasive direct coronary artery bypass (MIDCAB) surgery involves monitoring hemodynamic parameters, ST segment changes, and arrhythmias.
- Understanding these changes during coronary artery clamping and reperfusion is crucial for patient safety.
Purpose of the Study:
- To monitor hemodynamic parameters, ST segment changes, and arrhythmias during coronary artery clamping and reperfusion in MIDCAB surgery patients.
- To identify potential risk factors associated with adverse events during the procedure.
Main Methods:
- Twelve patients undergoing elective MIDCAB surgery under isoflurane anesthesia were studied.
- Hemodynamic parameters, ST segment changes, and arrhythmias were monitored using a pulmonary artery thermodilution catheter, arterial line, and 5-lead ECG.
- Data were compared to baseline control values before and after coronary artery clamping and reperfusion.
Main Results:
- Coronary artery clamping did not significantly alter cardiac index but caused significant ST segment elevation.
- Following reperfusion, ST segments returned to baseline, and cardiac index increased significantly.
- Four patients developed ventricular extrasystoles post-reperfusion, associated with higher ST segment elevation during clamping and risk factors like prior arrhythmias or unstable angina.
Conclusions:
- Coronary occlusion during MIDCAB can lead to ST segment elevation and subsequent reperfusion arrhythmias.
- Patients with significant ST elevation during occlusion and risk factors like unstable angina or recent MI are more prone to reperfusion arrhythmias.
- Isoflurane anesthesia may offer myocardial protection, evidenced by rapid ST segment normalization and increased cardiac output post-reperfusion.
Background And Objectives:
The objective of the report is to monitor, in patients undergoing minimally invasive direct coronary artery bypass surgery (MIDCAB), the haemodynamic parameters, ST segment changes and the incidence of arrhythmias during clamping of the coronary artery and following reperfusion.
Methods:
Twelve patients scheduled for elective MIDCAB surgery during isoflurane anesthesia were enrolled in the study. Patients were monitored by a pulmonary artery thermodilution catheter, an arterial line and 5 leads ECG. The different haemodynamic parameters, the ST segment changes, as well as the occurrence of arrhythmias during coronary clamping and ten minutes following reperfusion were compared to the control values.
Results:
No significant changes in the cardiac index followed clamping of the coronary artery. However, the ST segment was significantly elevated. Following coronary reperfusion, the ST segment recovered to the baseline values, and the cardiac index significantly increased more than the baseline value (3.5 +/- 1.1 l/min/m2 vs 2.6 +/- 0.7 l/min/m2). However, reperfusion was associated with multiple ventricular extrasystoles in four patients. The elevation of the ST segments during coronary clamping was higher in the four patients who developed reperfusion arrhythmias (0.9 +/- 0.4 mm); one of the patients had preoperative frequent VPBs, two patients had history of unstable angina, while the fourth patient had 70% proximal stenosis of the LAD and recent myocardial infarction.
Conclusions:
Coronary occlusion in patients undergoing MIDCAB can result in ST segment elevation, followed by reperfusion ventricular extrasystoles. The reperfusion arrhythmias were observed in patients showing a significant elevation of the ST segment during coronary occlusion; risk factors included a preoperative history of arrhythmia, unstable angina, recent MI, and/or 70% LAD stenosis. The rapid restoration of the control ST segment level and the significant increase of cardiac output following coronary reperfusion suggest that isoflurane anesthesia may have provided a degree of myocardial protection during coronary clamping and reperfusion.