Role of heart rate reduction in the treatment of exercise-induced XXXX .

@entity296 @entity235 @entity409 @entity3979 @entity2165 @entity1168
The role of @entity1168 in reducing exercise-induced ischaemia and @entity409 was examined in @entity235 with single vessel chronic @entity3979 created using an ameroid constrictor. Treadmill exercise produced significant regional @entity296 (blood flow measured using microspheres) and @entity409 (systolic wall thickening measured with sonomicrometers). @entity235 were initially studied during a control run before and during a second identical run after administration of the cardioselective beta-adrenergic blocker @entity2165 , which improved regional ischaemic function from 4.4 +/- 3.7% to 8.5 +/- 2.8% and subendocardial perfusion from 0.43 +/- 0.23 to 0.55 +/- 0.29 ml min-1 g-1. In another group of @entity235 during a run with @entity2165 , the heart rate was paced to match the rate observed in the control run. During the @entity2165 run with pacing, all beneficial effects of @entity2165 observed at the reduced exercise heart rate were lost. A third group of @entity235 received the bradycardic agent UL-FS 49 (1.0 mg kg-1, i.v.) prior to exercise. UL-FS 49 produced a heart rate reduction during exercise from 230 +/- 19 to 139 +/- 10 beats min-1; this was associated with an increase in systolic wall thickening from 9.3 +/- 5.0% (during the control run) to 21.5 +/- 8.4%, thereby eliminating the exercise-induced @entity409 . Transmural myocardial blood flow per beat to the poststenotic myocardium was improved significantly from 4.8 X 10(-3) +/- 1.9 X 10(-3) ml beat-1 to 9.8 X 10(-3) +/- 1.7 X 10(-3). Atrial pacing to match heart rate to the control exercise rate during the UL-FS 49 run did not eliminate all of the improvement in systolic wall thickening.(ABSTRACT TRUNCATED AT 250 WORDS)
