| Relationship of neurosympathetic responsiveness to early ventricular arrhythmias in ischaemic myocardium (1984) | |||||||||||
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| Myocardial catecholamine overflow has been measured in open-chest anaesthetised dogs after graded stimulation of the left ansa subclavia before and during left anterior descending coronary artery occlusion and on reperfusion. Sequential 1 min periods of ansa stimulation over 3 h resulted in reproducible, frequency dependent regional myocardial noradrenaline (NA) overflow without tachyphylaxis. In seven dogs, two successive 10 min periods of LAD occlusion did not modify peak myocardial NA overflow from the predominantly ischaemic (I) or non-ischaemic (NI) areas at either low (1 Hz) or high (10 Hz) frequency ansa stimulation. In a second group of nine dogs, myocardial catecholamine overflow was related to changes in ischaemic area epicardial activation delay during repeated ansa stimulation on four occasions during 75 min of ischaemia. Stimulation at the period of peak spontaneous arrhythmias 5 and 17 min after coronary occlusion resulted in NA overflow from I of 2.8±1.3 and 3.0±1.6 pmol·ml–1 respectively and a significant increase in mean activation delay in I of 12±4 ms at 5 min and 9±4 ms at 17 min (p | |||||||||||
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