Electrocardiographic Changes During Cesarean Section

A Holter monitor was used to record ST segment changes during cesarean section in 170 consecutive healthy parturients starting 2 h before and ending 3 h after surgery. Lumbar epidural anesthesia (LEA, n = 120) or subarachnoid anesthesia (SA, n = 50) was used. Transthoracic 2-D echocardiograms were obtained in 30 patients from the LEA group. ST depression or elevation occurred 160 times in 44 patients from both groups. Ninety-eight percent of these changes occurred between induction of anesthesia and the end of surgery, with 78% of the episodes registering -1 mV. In the LEA group, the number of episodes tended to increase after delivery, but in the SA group, the frequency remained constant. ST segment depression was recorded in 38% and 14% of patients in the LEA and SA groups, respectively (P < 0.05, x2 analysis). No wall motion abnormality was noted in the echocardiogram during ST segment depression. Neither the 12-lead electrocardiogram nor plasma myocardial specific creatine kinase suggested myocardial damage. The operative events, alone or in combination, including hypertension, tachycardia, hypotension, bradycardia, air embolism (precordial Doppler) were neither specific nor sensitive as predictors of ST segment change (stepwise logistic regression). Tachycardia was associated with ST segment changes in 10% of time epochs (5 min) (P = 0.05, x2 analysis). Thus, ST segment changes during cesarean section are not caused by myocardial ischemia and are not of any clinical consequence.