Ischemia and reperfusion-induced arrhythmias: role of hyperoxic preconditioning

Abstract

f Background Hyperoxic preconditioning is known to protect the heart against necrosis and contractile dysfunction, but protection against arrhythmias has not been well characterized.Objective The authors hypothesized that pre-exposure to normobaric hyperoxia (H) reduces ischemia and reperfusion-induced arrhythmias in isolated rat hearts.Methods Following 60 and 180 min of hyperoxia treatment, rat hearts were isolated immediately (H60 and H180) or 24 h afterward (H60/24 and H180/24), and subjected to 30 min of regional ischemia followed by 120 min of reperfusion. Occurrence, number, and duration of arrhythmias were analyzed during ischemia and reperfusion. In addition, cardiac infarct size was also assessed.Results Sixty and 180 min of breathing hyperoxic gas induced significant protection against severe ischemia and reperfusion-induced arrhythmias. Total number of premature ventricular beats was markedly attenuated by hyperoxia pre-exposure, especially in H60 and H180 groups. Duration of ventricular tachycardia and ventricular fibrillation was also affected by hyperoxia. Hyperoxia reduced the number of ventricular tachycardia episodes in ischemia and reperfusion phase. Accordingly, severity of arrhythmias (arrhythmia score) and infarct size were lower in hyperoxia-treated groups. The effects were more pronounced using hyperoxia immediately before harvesting the heart.Conclusion These results indicate that hyperoxic preconditioning attenuates ventricular ischemia and reperfusion-induced arrhythmias in isolated rat hearts, decreases cardiac infarct size, and improves postischemic heart function. The effects seem to depend on the time course after hyperoxia treatment.

Comparison of cardioprotective and anti-inflammatory effects of ischemia pre- and postconditioning in rats with myocardial ischemia–reperfusion injury

“…Furthermore, IPC measurably decreased ventricular arrhythmia during the initial period of reperfusion, though no significant difference in incidence and scores of ventricular arrhythmia between the control and IPC groups was achieved because of the small sample size. These results correspond with the findings of previous studies in rats with myocardial IRI in vivo [18][19][20]. The results of the present study also showed that IPOC produced a significant inhibitory effect on ventricular arrhythmia during the initial period of reperfusion.…”

“…The severity of arrhythmias was quantified by a scoring system, where hearts without arrhythmias were given a score of 0, premature ventricular beats (PVB) only a score of 1, bigeminy/salvos a score of 2, VT a score of 3, frequent VT or transient VF a score of 4, and a score of 5 was given to the hearts with frequent or sustained VF or death of the rat. The number corresponded to the most severe type of arrhythmia observed in each heart, and scores were used for intergroup analysis of their severity [17,18].…”

Cardiovascular effects of hyperoxia during and after cardiac surgery

“…Animal studies suggest that hyperoxia has favourable effects on myocardial ischaemic injury through a preconditioning effect on cardiac muscle . A similar study in humans, exposing patients to hyperoxia (F I O 2 > 0.96) for 130 and 60 min before coronary artery bypass grafting, had no effect on the cardiac enzymes creatine kinase MB (CK‐MB) and troponin I .…”

Pharmacological screening of substances with cardioprotective effect in the group of 3-oxypyridine derivatives

“…Since ROS is considered to be one of the main factors triggering the mechanism of death in ischemic/reperfusion myocardial damage, the prevention of the synthesis of ROSs or their neutralization is obviously crucial for the survival or recovery of cardiomyocyte function (Pourkhalili et al 2009). The pharmacological group used for this purpose is antioxidants.…”