RESUMO
Objective Previous studies showed that hypoxia preconditioning could protect cardiac function against subsequent myo-cardial infarction injury. However, the effect of hypoxia on left ventricular after myocardial infarction is still unclear. This study therefore aims to investigate the effects of hypoxia training on left ventricular remodeling in rabbits post myocardial infarction. Methods Adult male rabbits were randomly divided into three groups: group SO (sham operated), group MI (myocardial infarc-tion only) and group MI-HT (myocardial infarction plus hypoxia training). Myocardial infarction was induced by left ventricular branch ligation. Hypoxia training was performed in a hypobaric chamber (having equivalent condition at an altitude of 4000 m, FiO214.9%) for 1 h/day, 5 days/week for four weeks. At the endpoints, vascular endothelial growth factor (VEGF) in the plasma was measured. Infarct size and capillary density were detected by histology. Left ventricular remodeling and function were as-sessed by echocardiography.Results After the 4-week experiment, compared with the group SO, plasma VEGF levels in groups MI (130.27 ± 18.58 pg/mL,P< 0.01) and MI-HT (181.93 ± 20.29 pg/mL,P< 0.01) were significantly increased. Infarct size in Group MI-HT (29.67% ± 7.73%) was deceased remarkably, while its capillary density (816.0 ± 122.2/mm2) was significantly increased. For both groups MI and MI-HT, left ventricular end-diastolic and end-systolic dimensions were increased whereas left ventricular ejection fraction was decreased. However, compared with group MI, group MI-HT diminished left ventricular end-diastolic (15.86 ± 1.09 mm,P< 0.05) and end-systolic dimensions (12.10 ± 1.20 mm,P< 0.01) significantly and im-proved left ventricular ejection fraction (54.39 ± 12.74 mm,P< 0.05).ConclusionHypoxia training may improve left ven-tricular function and reduce remodeling via angiogenesis in rabbits with MI.
RESUMO
Objective To investigate the effect of delayed PTCA and stenting for infarct related artery on the chronic phase of left ventricular remodelling and cardiac events in patients with acute myocardial infarction. Methods Fifty two patients with primary acute myocardial infarction were divided into PTCA group ( n =27) and non PTCA group ( n =25). Twenty seven patients underwent PTCA and coronary stenting with an average of 12 days after the acute onset. Left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), left ventricular ejection fraction (LVEF) and cardiac events in each group were followed up. Results There were no significant differences in preoperation and postoperation for LVEDV and LVESV in the PTCA group, on the contrary a significant increase for before and after follow up for LVEDV and LVESV in the non PTCA group( P 0.05). Conclusions Delayed PTCA and stenting for infarct related artery would inhibit ventricular enlargement and delay chronic phase of left ventricular remolding. Moreover, cardiac events were significantly reduced in patients with acute myocardial infarction after delayed PTCA and stenting.