Effects of exercise on dynamic cardiac function and survival after myocardial infarction / 中华物理医学与康复杂志

ABSTRACT

Objective To study the effects of exercise after myocardial infarction on the survival rate and the dynamic functioning of the left ventricle ( LV) . Methods Ninety-six male Sprague-Dawley rats were randomly assigned to a sedentary sham operation group ( Sed-Sh) , a previous exercise and sham operation group ( PreE-Sh) , a sedentary myocardial infarction ( MI) group ( Sed-MI) , a previous exercise MI group ( PreE-MI) , a post exercise MI group (PostE-MI) and a combined exercise MI group (ComE-MI), each of 16.All of the rats underwent either MI in-duction or a sham MI operation, the PreE groups after exercising for 5 weeks on a treadmill. The Sed groups did not exercise. The Post E-MI group did not exercise before the operation, but performed treadmill exercises for 4 weeks be-ginning 8 weeks after the operation. The ComE-MI group exercised for 5 weeks before and 4 weeks after the operation. All the exercising rats ran on the treadmill for 60 minutes daily, 5 d/wk. Life situation and spontaneous mortality were recorded, and echocardiographic measurements were performed on the4thday and 2, 4, 8 and 12weeks after the oper-ation. All of the rats were sacrificed at the end of the experiment. Results Compared with the Sed-Sh group, the Sed-MI group had significantly larger average LV dimensions at the end of both the diastol ( LVEDd) and the systol (LVEDs, but it had lower average fractional shortening (FS) and a smaller average ejection fraction(EF) at all of the different measuring times. The PreE-MI group had significantly lower average LVEDd and LVEDs, but a signifi-cantly higher FS and EF than the Sed-MI group on the 4th day. However, 2 weeks after the intervention the difference in LVEDd between the two groups was no longer significant. Significantly higher FS and EF were observed in the PostE-MI group at 12 weeks compared to the Sed-MI group. The ComE-MI group had significantly lower average LVEDd and LVEDs, but significantly higher FS and EF at all the time points than the Sed-MI group. The ComE-MI group had a significantly lower average LVEDs but a higher average FS and EF than the PreE-MI group at 12 weeks after the intervention. Conclusion Pre-MI exercise improves LV function significantly at the early stage, though the difference is temporary. Post-MI exercise improves LV function in the longer term. Combined exercise improves LV function the most effectively.