Journal of cardiothoracic and vascular anesthesia
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J. Cardiothorac. Vasc. Anesth. · Dec 1992
QRS complex changes in the V5 ECG lead during cardiac surgery.
The QRS complex in lead V5 was studied during cardiac surgery. R wave amplitude decreased after induction of anesthesia to approximately 50% to 60% of the preanesthetic level before the institution of CPB (P < 0.001). An rS complex appeared immediately after cardioversion and changed in configuration to an Rs complex 15 to 30 minutes after aortic declamping. ⋯ Nonsurvivors had much smaller R waves (26.1 +/- 20.5%) than survivors (P < 0.001). The R wave peaked 30 to 40 ms after initiation of the QRS complex, which indicates recovery of conductivity and the activation sequence of the left ventricular (LV) free wall, which is easily disturbed by hypothermia, cardioplegia, and ischemia during aortic cross-clamping. Monitoring QRS complex changes in lead V5 appears to be important on weaning from cardiopulmonary bypass to detect regional ischemia, and also to observe electrophysiologic recovery of the LV free wall.