[Automated, continuous ST segment analysis in the ECG as a monitor of myocardial ischemia during aortocoronary bypass surgery].
Patients with coronary artery disease (CAD) who are subjected to cardiac and major noncardiac surgical procedures have a high incidence of perioperative myocardial ischemia. Earlier studies in patients undergoing coronary artery bypass graft surgery (CABG) indicated the frequency of postoperative myocardial infarction to be directly proportional to the incidence and severity of pre-bypass myocardial ischemia.


METHODS
We investigated the incidence of pre-bypass ischemia in 50 patients undergoing elective CABG using an automated ST segment monitoring system (Marquette 7010). Analyzing leads I, II, and V5, this device measures ST segment deviations 60 ms after the J-point. Occurrence of myocardial ischemia was defined as follows: new ST segment deviations larger than 1 mm = 0.1 mV that lasted for more than at least 10 consecutive heartbeats.


RESULTS
In 19 out of 50 patients (38%) we found 96 episodes of myocardial ischemia in the pre-bypass period; 47% of all ischemic episodes were associated with significant hemodynamic changes, e.g., tachycardia, hypertension, or hypotension. The incidence of ischemia was different between population sub-groups: patients with a previous infarction had a lower incidence of ischemia (35%) than patients without infarction (44%). Patients with preoperative left ventricular end diastolic pressure (LVEDP) less than 15 mm Hg had a lower incidence of ischemia (29%) than patients with LVEDP greater than 15 mm Hg (50%). Patients treated preoperatively with beta-blockers showed a significantly lower incidence of ischemia (9%) when compared to untreated patients (46%, p less than 0.05). No difference was found between patients with or without unstable angina pectoris or between patients of NYHA classes II, III, or IV. Postoperative myocardial infarction occurred in 2 patients, both with evidence of pre-bypass myocardial ischemia.


CONCLUSIONS
Our study confirms that automated ST segment analysis is able to detect myocardial ischemia similarly to that documented in previous studies using conventional ECG lead analysis.
Zentrum der Anaesthesiologie und Wiederbelebung der Johann Wolfgang Goethe-Universität, Frankfurt am Main.
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D000368:Aged; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000150:complications / Q000175:diagnosis*; D004562:Electrocardiography / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D011183:Postoperative Complications / Q000517:prevention & control
Automatisierte, kontinuierliche ST-Strecken-Analyse im EKG als Monitoring myokardialer Ischämien bei aortokoronarer Bypassoperation.