Our study dealt with only one aspect of preconditioning: the effect on tachyarrhythmias. The most classical presentation of preconditioning – attenuation of ischemic necrosis -was not addressed. Various facets of preconditioning probably have different mechanisms . Our results suggest that preconditioning may have peculiar effects on coronary flow and noradrenaline release. This suggests that […]
During brief regional ischemia-reperfusion, the protective substances or pathways may originate from either the border zone or from the ischemic tissue. In the global model of ischemic preconditioning, the amount of tissue is greater, but signals arising from the border zone are probably absent. When preconditioning by either global or regional brief ischemia results in […]
The development of tachyarrhythmias on reperfusion is a manifestation of increased electrical vulnerability of injured but viable myocardium. Its incidence has a bell-shaped relationship with the preceding ischemia duration, peaking at about 15 mins of ischemia . Lawson and colleagues found attenuation of reperfusion tachyarrhythmias without altering the relationship with the duration of the preceding […]
DISCUSSION Reperfusion tachyarrhythmias are common following either global or regional ischemia of the rat heart . Previous studies demonstrated that heart preconditioning attenuates tachyarrhythmia . These results were obtained mostly with regional ischemia. Furthermore, this effect was dependent on the intensity of preconditioning but not on the duration of sustained ischemia .
Noradrenaline: Noradrenaline release is presented in Figure 1. There was some basal release of noradrenaline in all groups (differences were not significant). At the first minute of reperfusion, noradrenaline release was higherthan at baseline, particularly after 30 mins of global ischemia. Noradrenaline outflow in group 5 appeared to be higher than in group 4. However, […]
At reperfusion following 30 mins of global ischemia, premature ventricular complexes were recorded in all hearts from each group. Within 60 to 90 s rhythm disturbances deteriorated into tachyarrhythmia (ventricular tachyarrhythmia-ventricular fibrillation) in five of the controls and in eight to nine of the preconditioned hearts, thus creating a significant difference in the overall reperfusion […]
Preconditioning by global ischemia before 30 mins of regional ischemia almost completely abolished ischemic tachyarrhythmia. Preconditioning by regional ischemia before 30 mins or regional ischemia almost completely abolished reperfusion tachyarrhythmia. No protective effect was found against ischemic arrhythmias when preconditioning was induced by regional ischemia and against reperfusion tachyarrhythmia when preconditioning by global ischemia preceded […]