Hypoxia training attenuates left ventricular remodeling in rabbit with myocardial infarction

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.

Beneficial Effects of Delayed Opening the Infarct - related Artery on Late Phase Left Ventricular Function in Acute Anterior Myocardial Infarction

Objectives To assess the effect of delayed opening the infarct - related artery (IRA) by percutanous coronary intervention (PCI) on the late phase left ventricular function after acute ante- rior myocardial infarction. Methods 64 patients with initial Q - wave anterior myocardial infarction and the infarct - related arteries were total occluded conformed by angiogram at 2 to 14 days after onset were divided into successful PCI group and control group ( not re- ceiving PCI or the IRA not re - opened). 2 - DE was performed at early phase ( about 3 weeks) , 2 and 6 months after onset of AMI respectively to detect the left ventricular function and left ventricular wall motion ab- normality (VWMA). The total congestive heart failure events were recorded during 6 months follow-up. Re- sults VWMA scores, left ventricular ejection frac- tion (LVEF) , left ventricular end - diastolic and end - systolic volume indices ( LVEDVI and LVDSVI) were similar in 2 groups at early phase and 2 months. There were no differences between early phase and 2 months in each group too. VWMA scores and LVEF did not changed at 6 months in each group compared with the early phase and 2 months ( P > 0. 05 ). But LVEDVI and LVESVI were significantly smaller in the successful PCI group than in the control group (P < 0.01, P < 0. 05). The congestive heart failure events were taken place in 19% of patients in control group com- pared with 2% in successful PCI group ( P > 0. 05 ). Conclusions Although the infarct size does not changed, delayed opening the IRA has beneficial effect to the late phase left ventricular dilatation after acuteanterior myocardial infarction.

Viable Myocardium Impact on Left Ventricular Function after Late Revascularization of Infarct-related Artery in Acute Myocardial Infarction

Objectives The long-term benefit of late reperfusion of infarct-related artery （IRA） after acute myocardial infarction （AMI） is controversial, and the benefit mechanisms remain uncertain. Low dose dobutamine stress echocardiography （LDSE） can identify viable myocardium and predict improvement of wall motion after revascularization. Methods Sixtynine patients with first AMI who did not received early reperfusion therapy were studied by LDSE at 5 to 10 days after AMI. Wall motion abnormality and left ventricular size were measured at the same time. Successful PCI were done in all patients at 10 to 21 days after AMI onset. Patients were divided in two groups based on the presence or absence of viable myocardium. Echocardiography was repeated six months later. Results There were 157 motion abnormality segments. 89 segments （57%） were viable during LDSE. 26 patients （38%） with viability and 43 （62%） without. In viable group, left ventricular ejection fraction （LVEF） was increased （P 〈 0.05）, and left ventricular end systolic volume index （LVESVI） and wall motion score （WMS） were decreased （P 〈 0.05 and P 〈 0.01） significantly at 6 months compared with baseline. But in patients without viability, LVEF was decreased （P 〈 0.01）, and LVESVI and left ventricular end diastolic volume index （LVEDVI） were increased （P 〈 0.05） significantly after 6 months, and the WMS did not changed （P 〉 0.05 ）. LVEF increased （P 〈 0.05 ） and WMS decreased （P 〈 0.05） on LDSE during acute phase in patients with viability, but they were not changed in the nonviable group. Conclusions Late revascularization of IRA in patients with presence of viable myocardium after AMI is associated with long-term preservation left ventricular function and less ventricular remodeling. Improvement of left ventricular systolic function on LDSE indicates late phase recovery of left ventricular function after late revascularization.

BENEFICIAL EFFECTS OF NTG ON LEFT VENTRICULAR VOLUMES AND SYSTOLIC FUNCTION IN PATIENTS WITH MYOCARDIAL INFARCTION

The effect of sublingual administration and intravenous drip of nitroglycerin (SLNTG and IVNTG) on left ventricular volumes (LVVs) were studied and systolic function was quantitatively assessed with two-dimensional echocardiography (2DE) in 28 patients with myocardial infarction (MI), including 13 cases without heart failure (MI-NHF) in one group and 15 with heart failure (MI-HF) in another. The results showed that after SLNTG and IVNTG in both groups the heart rate (HR) increased significantly (P< 0.05-0.001); the systolic blood pressure (SBP) decreased significantly (P< 0.05-0.001); the diastolic blood pressure (DBP) was not significantly changed (all P>0.05); the left ventricular end-diastolic and end-systolic volumes (EDV and ESV) both significantly reduced [EDV: decreased by 5.8-11.6% (-13.2-19.0 ml), P< 0.05-0.001; ESV: decreased by 9.6-16.6% (-8.6-17.3 ml), P< 0.05-0.001)1; the left ventricular ejection fraction (LVEF) all significantly elevated (increased by 6.6%-9.4% (3.2%-3.4%), P < 0.05-0.001] except in MI-NHF group after IVNTG; the segmental EF of normal and hypokinetic segments also significantly increased (P<0.05-0.001). The results suggest that NTG could beneficially reduce left ventricular EDV and ESV; and improve or strengthen its global and segmental systolic function in MI patients, particularly noticeable in patients with heart failure.

Long-term effects of bone marrow-derived cells transplantation in patients with acute myocardial infarction： a meta-analysis

Background The long-term effects of bone marrow-derived cells （BMC） transplantation in patients with acute myocardial infarction （AMI） have not been established. The present meta-analysis of randomized controlled trials with follow-up 〉2 years was performed to investigate the long-term effects of BMC therapy in patients after AMI. Methods Specific terms were used to conduct a systematic literature search of MEDLINE, EMBASE, the Cochrane Library and the Cochrane Central Register of Controlled Trials, and the China Biological Medicine Disk database from their inception to March 2012. A standardized protocol was used to extract information, and random effect model was used to analyze all data except major adverse events. Results Five trials comprising 510 patients were included. Compared with controls, BMC therapy significantly improved left ventricular ejection fraction （LVEF） （4.18%, 95% CI： 2.02% to 6.35%, P=-0.0002）, while mildly but not significantly reduced left ventricular end-systolic volume （-4.47 ml, 95% CI： -10.92 to 1.99, P=-0.17） and left ventricular end-diastolic volume （-2.29 ml, 95% CI： -9.96 to 5.39, P =0.56）. Subgroup analysis revealed that significant improvement of LVEF induced by BMC therapy could be observed in patients with baseline LVEF 〈42%, but disappeared in those with baseline LVEF 〉42%. There were trends in favor of BMC therapy for most major clinical adverse events, though most differences were not significant. Conclusions Intracoronary BMC infusion in patients with AMI seems to be safe and may further improve LVEF on top of standard therapy; especially the beneficial effects could last for long term. The findings need to be validated in the future.

Effect of Different Styles of Coronary Heart Disease and Its Risk Factors on Cardiac Remodeling and Dysfunction

Objectives To evaluate the effect of different styles of coronary heart disease （CHD）, different regions of acute myocardial infarction （AMI）, its risk factors and branches of coronary stenosis on left ventricular remodeling and dysfunction by applying echocardiography. Methods 251 patients with CHD and 96 patients without CHD （NoCHD） were verified by selective coronary angiography. CHD patients were divided into stable angina pectoris （SAP） 26, unstable angina pectoris（UAP） 53, acute myocardial infarction （AMI） 140 and old myocardial infarction （OMI） 30 based on clinical situation, cTnT, cardiac enzyme and ECG. AMI patients were further divided into subgroups including acute anterior myocardial infarct （Aa,n = 53）, acute inferior myocardial infarction （Ai, n=54） and Aa＋Ai （n=33） based on ECG. Cardiac parameters： end-diastolic interventricular septum thickness（IVSd）, end-diastolic left ventricular internal diameter （LVd）, left ventricular mass （LM）, end-diastolic left ventricular volume （EDV）, end-systolic left ventricular volume （ESV） and left ventricular ejection fraction（LVEF） were measured by ACUSON 128XP/10 echocardiography. Multiples linear regression analyses were performed to test statistical associations between LVEF and the involved branches of coronary stenosis, blood pressure, lipids, glucose and etc after onset of myocardial infarction. Results EDV and ESV were increased and LVEF decreased on patients with AMI,OMI and UAP （P〈0.05-0.0001）. LM was mainly increased in patients with OMI （P〈0.01） and LVd was mainly enlarged in patients with AMI. EF was significantly decreased and EDV, ESV, LM and LVd were remarkably increased in AMI patients with Aa and Aa＋Ai. With the multiple linear regression analyses by SPSS software, we found that LVEF was negatively correlated to the involved branches of coronary stenosis as well as to systolic blood pressure after onset of myocardial infarction while there was no significant correlation between LVEF and other factors. LVEF was significantly decreased, and LVd and LM increased in AMI patients with antecedent hypertension, compared to patients without hypertension （P〈0.001）. Conclusions Effects of different styles of CHD and different regions of AMI on left ventricular remodeling and cardiac function are different. Myocardial infarction, especially Aa and Aa＋Ai, is one of the most important causes of left ventricular remodeling and cardiac dysfunction. Multiple vessel stenosis and systolic blood pressure at the onset of myocardial infarction reduce LVEF in AMI patients. Antecedent hypertension may accelerate the effect of AMI on cardiac remodeling and dysfunction. Therefore primary and secondary preventions of CHD are critical for protecting heart from remodeling and dysfunction.