Prior exercise training and experimental myocardial infarction: A systematic review and meta-analysis

Exercising prior to experimental infarction may have beneficial effects on the heart. The objective of this study was to analyze studies on animals that had exercised prior to myocardial infarction and to examine any benefits through a systematic review and meta-analysis. The databases MEDLINE, Google Scholar, and Cochrane were consulted. We analyzed articles published between January 1978 and November 2018. From a total of 858 articles, 13 manuscripts were selected in this review. When animals exercised before experimental infarction, there was a reduction in mortality, a reduction in infarct size, improvements in cardiac function, and a better molecular balance between genes and proteins that exhibit cardiac protective effects. Analyzing heart weight/body weight, we observed the following results - Mean difference 95% CI - -0.02 [-0.61,0.57]. Meta-analysis of the infarct size (% of the left ventricle) revealed a statistically significant decrease in the size of the infarction in animals that exercised before myocardial infarction, in comparison with the sedentary animals -5.05 [-7.68, -2.40]. Analysis of the ejection fraction, measured by echo (%), revealed that animals that exercised before myocardial infarction exhibited higher and statistically significant measures, compared with sedentary animals 8.77 [3.87,13.66]. We conclude that exercise performed prior to experimental myocardial infarction confers cardiac benefits to animals.

A Cross Sectional Study among Type 2 Diabetes Cases with Silent Myocardial Ischaemia in a Tertiary Care Center in a Northern Maharahstra

Introduction: Silent myocardial ischemia is definedas objective evidence of myocardial ischemia withoutangina or angina equivalent. In Framingham study, 30% ofmyocardial infarcts were silent, diagnosed only by serialelectrocardiography. There is increasing evidence thatasymptomatic myocardial infarctions and silent ischemiaoccur more frequently in diabetic patients. So present studywas done to record the prevalence of silent myocardialischemia in asymptomatic patients of type 2 diabetes mellitus.Material and methods: The present study was a crosssectional study, carried out among 88 randomly selectedpatients of type 2 diabetes mellitus for more than 1 year,patients >18 years of age, who do not have any symptomsrelated to cardiovascular system.Results: Our study shows that the prevalence of silent MIamong patients with DM was 20.45%. It was reported inthe present study that the mean fasting and post prandialblood sugar among patients was 162.23±12.18 mg/dl and192.4±21.29 mg/dl respectively.Conclusion: Our study shows that the prevalence of silent MIamong patients with DM was 20.45%. In our study majorityof cases of silent myocardial ischemia were found in patientswith age group of >50 years, patients with duration of diabetesmellitus of 5-10 years

Very Early Onset of Amiodarone-Induced Pulmonary Toxicity

Amiodarone is a widely used antiarrhythmic agent. Among its various adverse effects, amiodarone-induced pulmonary toxicity (APT) is the most life threatening complication, which has been described mostly in patients who have been in treatment with high accumulative doses for a long duration of time. However, amiodarone therapy in short-term duration induced APT was rarely reported. We describe a case of a 54-year-old man who is presented with symptoms of APT after a few days of therapy for post-myocardial infarction ventricular tachycardia. For early diagnosis and successful treatment, awareness and high suspicion of this rare type of early onset APT is crucial in patients with amiodarone therapy.

Value of two-dimensional speckle tracking imaging in assessing myocardial injury in various degree of rats / 中华超声影像学杂志

Objective To investigate the value of left ventricular global two-dimensional strain and strain rate index measured by two-dimensional speckle tracking imaging (2D-STI) in assessing myocardial injury in various degree of rats following acute myocardial infarction. Methods Fifty-five Wistar rats were randomly divided into myocardial infarction(MI) group ( n =45) and sham-operation(SO) group ( n = 10).To establish rats acute myocardial infarction model with different infarct extent, MI group were randomly divided into MI15 group,MI30 group and ML60 group( n = 15,respectively) which underwent occlusion of left anterior descending coronary artery for 15 minutes, 30 minutes and 60 minutes respectively. Echocardiography was performed at baseline and 24 hours after reperfusion. High frame rate twodimensional images were recorded from the left ventricular short-axis views at the papillary muscle level.Left ventricular global circumferential strain(GSc) and strain rate(GSRc) were measured using EchoPAC work station. Left ventricular internal diameter at diastole (LVIDd) and systole ( LVIDs), fractional shortening(FS) and ejection fraction(EF) were measured by anatomical M-model echocardiography. Area of necrosis(AN) of each segment was measured after triphenyl tetrazolium chloride(TTC) staining. Results ① Compared with baseline and SO group, LVIDd and LVIDs of MI15, MI30 and MI60 group significantly increased respectively,whereas FS and EF significantly decreased( P <0. 05). Compared with MI15 group and MI30 group, LVIDd and LVIDs of MI60 group significantly increased, whereas FS and EF significantly decreased(P <0. 05). ② Compared with baseline and SO group,GSc and GSRc of MI15 group, MI30 group and MI60 group significantly decreased. GSc and GSRc of MI group decreased with ischemia duration ( P <0.05). ③ GSc and GSRc significantly correlated with AN respectively ( P <0. 01) while the correlation coefficient was 0. 90 and 0. 88 respectively, and GSc and GSRc were significantly predictors of AN( P <0.01) while the Beta was 0.558 and 0.491 respectively.④AN increased with ischemia duration( P <0.05). Conclusions Left ventricular global circumferential strain and strain rate index measured by 2D-STI,which decreased significantly as the area of necrosis increased, can accurately assess myocardial injury after myocardial infarction in various degree.

The effect of β-adrenoceptor blockers on G protein and heart function in rats with acute myocardial infarction / 中华老年医学杂志

ObjectiveTo investigate the effect of β-adrenoceptor (β-AR) blockers on G protein and heart function changes in rats with acute myocardial infarction (AMI) MethodsWistar rats with AMI induced by left anterior descending coronary branch ligation were randomly divided into compared with sham operation group. Eight weeks after therapy, hemodynamics was assessed by inserting catheters and the level of G protein was detected by Western blot analysis. ResultsCompared with the sham operation group, systolic blood pressure(SBP), diastolic blood pressure (DBP), left ventricular systolic pressure(LVSP) and left ventrieular pressure maximal rate of rise and fall(±dp/dtmax) in AMI group were significantly decreased, while left ventricular end diastolic pressure (LVEDP) and Gs and Gi protein levels were significantly increased (all P<0.05). Compared with AMI group, LVSP and ± dp/dtmax were increased, but LVEDP and Gi protein level were significantly decreased in metoprolol and carvedilol group. LVEDP and Gi protein level were decreased in carvedilol group compared with metoprolol group. ConclusionsCarvedilol can effectively suppress the change of G protein and improve the heart function after AMI, and the effect is better than that of metoprolol. This may be related with its β2-AR blocking effect.

Perspectivas de las células tallo en infartos del miocardio / Stem cell perspectives in myocardial infarctions

Myocardial infarction is the leading cause of congestive heart failure and death in industrializated countries. The cellular cardiomyoplasty has emerged as an alternative treatment in the regeneration of infarted myocardial tissue. In animals' models, differents cellular lines such as cardiomyocites, sheletal myoblast, embryonic stem cells and adult mesenchymal stem cells has been used, resulting in an improvement in ventricular function and decrease in amount of infarted tissue. The first three cells line have disvantages as they are allogenics and are difficult to obtain. The adult mesenchymal stem cells are autologous and can be obtained throught the aspiration of bone marrow or from peripherical circulation, prior to stimulating with cytokines (G-CSF). The implantation in humans with recent and old myocardial infarction have shown improvements similar to those shown in animal models. These findings encourage the continued investigation in the mechanism of cellular differentiation and implantation metods in infarted myocardial tissue.

El infarto del miocardio es la principal causa de falla cardiaca y muerte en países industrializados. A la fecha, la cardiomioplastia celular ha emergido como una alternativa en la regeneración de infartos miocárdicos. En modelos animales se han utilizado diferentes líneas celulares como cardiomiocitos fetales, mioblastos de músculo esquelético, células tallo embrionarias y células tallo mesenquimales del adulto, con mejoría en la función ventricular y disminución del área de tejido infartado. Las tres primeras líneas celulares tienen desventajas porque son alogénicas y difíciles de obtener. Las células tallo mesenquimales del adulto son autólogas y se pueden obtener de aspirados de médula ósea o de la circulación periférica previa estimulación con citocinas (G-CSF). La implantación de estas células en seres humanos con infartos del miocardio recientes y antiguos han mostrado mejorías similares a los reportes con modelos animales. Estos hallazgos alientan a continuar la investigación clínica y básica en busca de los mecanismos de diferenciación celular y selección de vías de implantación, en tejido miocárdico infartado.

Triple Intravenous Bolus Injection of Recombinant Tissue-Type Plasminogen Activator in Acute Myocardial Infarction

BACKGROUND: Previous studies indicated that there was important correlation between early patency of infarct-related artery, preservation of ventricular function, and improved survival after thrombolytic therapy for acute myocardial infarction. An increased infusion rate of rt-PA has been shown to result in faster thrombolysis and a high patency rate of occluded vessel in myocardial infarction. Therefore, we evaluated the effect of simplified triple bolus injection of rt-PA on early patency of infarct-related artery and evaluated safety and efficacy of triple bolus injection. METHOD: Patients with acute myocardial infarction presenting up to 6 hour from the onset of chest pain were recruited for the study. Aspring(100-200mg) was given immediately. Total dose for 1.5mg/kg of rt-PA(minimum 75mg, maximum 100mg) was administered as triple bolus intravenous injections. The half of total dose was injected initially, the quarter of total dose was injected at 10 minutes after 1st injection and the remainder was injected at 40 minutes after 1st injection. Five thousand units of heparin was given and 1,000-1,500unit/hr was given continuously. Coronary angiogram was performed at 60 minutes and 7-10 days after the first bolus injection. RESULTS: At 60 minutes, eleven of fourteen patients (78.6%) showed TMI grade-3 of patency in infarct-related coronary artery. There were two patients of hemorrhagic complications. One patient developed cerebellar hemorrhage at third day after rt-PA injection, and the other developed bleeding at femoral sheath site. There was no in-hospital mortality and reinfarction. CONCLUSION: In patients with acute myocardial infarction, the simplified triple bolus injection of rt-PA is associated with high early patency(TMI grade-3) in infarct-related coronary artery, with low risk of major bleeding comlications comparable to other studies.