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Perioperative myocardial ischemia in carotid endarterectomy under cervical plexus block and prophylactic
G Landesberg1, J Erel, H Anner
1Department of Anesthesiology, Hebrew University Hadassah Medical School, Jerusalem, Israel.
Insights
Myocardial ischemia during carotid endarterectomy surgery, detected by ST segment depression, is linked to cardiac complications. Monitoring ST segment trends may help predict and prevent these events in high-risk patients.
Area of Science:
- Cardiology
- Vascular Surgery
- Anesthesiology
Background:
- Patients undergoing carotid endarterectomy often have pre-existing ischemic heart disease.
- Perioperative myocardial ischemia is a significant concern in this patient population.
Purpose of the Study:
- To evaluate perioperative myocardial ischemia during carotid endarterectomy.
- To correlate electrocardiogram (ECG) findings with cardiac status and outcomes.
- To assess the utility of ST segment monitoring for predicting cardiac complications.
Main Methods:
- 36 carotid endarterectomy procedures were monitored.
- Continuous ECG and intra-arterial blood pressure were recorded.
- Patients received cervical plexus block and nitroglycerin infusion.
Main Results:
- 52.9% of procedures showed significant ST segment depression.
- 23.5% of ST depressions occurred during or shortly after carotid artery clamping/declamping.
- 11.7% of patients experienced postoperative cardiac events (myocardial infarction, unstable angina).
- All cardiac events were preceded by early signs of myocardial ischemia during clamping/declamping.
Conclusions:
- ST segment depression during carotid artery clamping or declamping is associated with cardiac complications.
- On-line ST segment trend monitoring may be useful for identifying patients at risk.
- Proactive cardiac monitoring is crucial for patients with ischemic heart disease undergoing carotid endarterectomy.
Abstract:
Perioperative myocardial ischemia was evaluated in 36 consecutive carotid endarterectomy procedures carried out on patients with a high (72.2%) prevalence of ischemic heart disease. The procedures were performed under cervical plexus block plus a prophylactic intravenous nitroglycerin infusion. Findings of myocardial ischemia on perioperative (48 hours) continuous electrocardiogram recordings were correlated with preoperative cardiac status, perioperative continuous intra-arterial blood pressure measurements, and postoperative cardiac outcome. In two patients, ST segment analysis was un-interpretable because of bundle-branch blocks. Altogether, 64 episodes of significant ST segment depression were detected in 18 (52.9%) of the remaining procedures. In 8 (23.5%) procedures, ST segment depressions occurred either during carotid artery clamping at the time of the largest rise in blood pressure or within 2 hours of declamping, when blood pressure tended to decline. There were four (11.7%) postoperative cardiac events: three myocardial infarctions (one Q wave and two non-Q wave) and one episode of unstable angina pectoris. All four patients with cardiac events had early signs of myocardial ischemia either at the time of cross-clamping, or soon after declamping of the carotid artery. All myocardial infarctions developed following prolonged (> 10 hours) myocardial ischemia, starting with the first 20 hours after surgery. Thus, ST segment depression occurring during clamping or soon after carotid declamping was associated with cardiac complications (sensitivity 100% and specificity 86.6%) and suggests the possible usefulness of on-line ST segment trend monitoring.