@entity5161 improves the tolerance to pacing-induced XXXX .

@entity1 @entity662 @entity308 @entity63 @entity951 @entity3810 @entity741 @entity5161
Fourteen @entity1 with normal, global, left ventricular function scheduled for elective myocardial revascularization were studied at rest and during atrial pacing before and during @entity5161 anesthesia (0.5% end-tidal) plus 50% @entity3810 . Rapid atrial pacing was performed in a stepwise fashion until the onset of @entity951 in the awake @entity1 . The same step increase in pacing rate was applied in the anesthetized @entity1 . Compared with prepacing baseline values, @entity5161 significantly decreased systemic blood pressure, coronary perfusion pressure, the rate-pressure product, and cardiac index. No @entity1 had ST-segment @entity308 while awake or during @entity5161 anesthesia before pacing was started. Prepacing left and right ventricular filling pressures and wave forms were normal, both while awake and during @entity5161 anesthesia. The mean pacing rate at which first signs of @entity741 appeared (V5 ST-segment @entity308 greater than or equal to 0.1 mV, increase in pulmonary capillary wedge pressure (PCWP) to greater than or equal to 15 mmHg, and prominent PCWP v-waves greater than or equal to 20 mmHg) was significantly higher during @entity5161 anesthesia than in the awake @entity1 (128 +/- 4 vs. 115 +/- 5 beats/min). With the exception of one @entity1 , the individual pacing rates inducing first signs of @entity63 in the awake @entity1 were below the anginal threshold. None of the @entity1 had a reduced @entity63 threshold during anesthesia. Eleven anesthetized @entity1 tolerated a higher pacing rate until initial signs of @entity63 appeared. In four of these @entity1 , the pacing rate required to induce first signs of @entity63 was above the heart rate at which @entity662 had been induced while they were awake. At a peak atrial pacing rate of 129 +/- 5 beats/min, which had induced @entity951 in the awake @entity1 , the increase in PCWP was significantly smaller during pacing with @entity5161 than during control pacing. Prominent PCWP v-waves (greater than or equal to 20 mmHg) appeared in 12 of the 14 @entity1 during initial pacing to angina and in eight @entity1 paced during @entity5161 anesthesia. In six of these eight @entity1 , the abnormal v-waves were less prominent than those observed during control pacing. Ischemic ST-segment changes developed in 13 of 14 @entity1 during initial pacing and in nine @entity1 during pacing with @entity5161 . Mean V5 ST-segment @entity308 during the two pacing periods was significantly different, averaging 0.19 and 0.11 mV, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
