Journal of cardiothoracic and vascular anesthesia
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J. Cardiothorac. Vasc. Anesth. · Dec 1993
Pacing-induced left ventricular asynchronies in dogs with critical coronary stenosis: mechanisms and effect of anesthetics.
The mechanisms leading to left ventricular (LV) asynchronies are incompletely understood, and reports on the functional significance of asynchronies for the affected segments are conflicting. To characterize LV asynchronies, 16 anesthetized dogs with critical stenosis of the left anterior descending coronary artery (LAD) were instrumented to measure subendocardial contractile function (sonomicrometry) and the ECG in the LAD territory. The subendocardial ECG was also recorded from the anterior basal LV territory. ⋯ LAD contractile dysfunction was considered as a systolic shortening below the normal range, and LV asynchronies as an onset time of segment shortening above the normal range. When LV asynchronies occurred, onset time of segment shortening in the LAD territory was 80.1 +/- 4.9 ms versus 14.8 +/- 3.7 ms at control (P < 0.01); the time difference between S wave arrival in the LAD and circumflex territories, however, was unchanged. LV asynchronies were associated with marked LAD territory contractile dysfunction (systolic shortening of 9.6 +/- 0.8% v 21.0 +/- 1.9% at control, after systolic shortening of 31.3 +/- 3.8% v 9.0 +/- 2.6% at control; P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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J. Cardiothorac. Vasc. Anesth. · Dec 1993
Use of the right-sided precordial lead V4R in the detection of intraoperative myocardial ischemia.
This study evaluated the benefit of additional electrocardiographic monitoring of the right precordial lead V4R for detection of ST segment changes during elective coronary artery bypass surgery in 210 patients. ST segment analysis was performed for leads I, II, CB5, and V4R. ST segment changes were noted in 60 patients. ⋯ In group B, this lead combination had a sensitivity of 93%, but lead combinations I-CB5-V4R and II-CB5-V4R were more sensitive (97% and 100%, respectively). The monitoring of lead V4R allowed detection of 20% of ST segment changes in group A that would have passed undetected if only leads I, II, and CB5 were monitored. These results demonstrate the value of additional electrocardiographic monitoring of the right precordial lead V4R during coronary artery bypass grafting in patients with right-sided coronary artery disease.
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J. Cardiothorac. Vasc. Anesth. · Dec 1993
Cardiac troponin T: a new marker of myocardial tissue damage in bypass surgery.
The purpose of this study was to evaluate cardiac troponin T (TnT) in the diagnosis of minor perioperative myocardial tissue damage and small myocardial infarctions during aortocoronary bypass surgery. In 15 patients without enzymatic or electrocardiographic signs of perioperative myocardial ischemia (group 1, uncomplicated bypass surgery), TnT did not exceed 3.55 micrograms/L. In 3 patients with perioperative non-Q-wave infarctions (group 2), TnT was significantly higher than in group 1 patients. ⋯ Thus, TnT indicated perioperative non-Q-wave infarctions not detected by CKMB activity in these 3 patients. These results are in accordance with findings in nonsurgical patients. They suggest a higher sensitivity and specificity of cardiac TnT compared to CKMB activity in the diagnosis of small perioperative myocardial infarctions after bypass surgery.