RhoA/ROCK pathway regulates hypoxia-induced myocardial cell apoptosis

Objective:To observe the regulatory effects of RhoA/ROCK pathway on the apoptosis of cardiac myocyte induced by anoxia and its mechanism.Methods:The model of cardiac myocyte anoxia was established.The beat pulsations and apoptosis rales after 1 h,3 h,6 h,9 h and 12 h of anoxia were recorded and the expressions of RhoA,ROCK1/2,p-PI3 K,p-AKT and caspae-3 were detected,too.The apoptosis and the expressions of related proteins were detected after RNAi of RhoA and the inhibition of ROCK by Y-27632.Results:The beat pulsations after 1 h,3 h,6 h.9h and 12 h decreased gradually but the apoptosis rates increased gradually,and the expressions of RhoA,ROCK1/2,p-P13 K,p-AKT and caspase-3 were increasing along with the increasing duration of anoxia.The apoptotic rales after 1 h,3 h,6 h.9 h and 12 h of anoxia were(4.36±0.98)%,(8.36±2.12)%,(15.32±3.62)%,(18.68±4.83)%and(24.56±6.22)%.respectively and decreased more significantly than control group in different time points of anoxia(P<0.05).and the expressions of RhoA,ROCK1/2,p-PI3 K,p-AKT and caspase-3 decreased significantly(P<0.05).The apoptosis rate and the expressions of RhoA,ROCK1/2,p-PI3 K,p-AKT and caspase-3 decreased significantly(P<0.05) after the inhibition of ROCK by Y-27632(P<0.05).Conclusions:RhoA/ROCK pathway plays a critical role in the regulation of the apoptosis of cardiac myocyte induced by anoxia,which may be accompanied by regulating the activity of PI3K/AKT/Caspase-3 pathway.

Comparative outcomes of subcutaneous and transvenous cardioverter-defibrillators

Background: The comparative outcomes of subcutaneous implantable cardioverter-defibrillator (S-ICD) and transvenous (T-ICD) have not been well studied. The aim of this study was to evaluate the safety and efficacy of currently available S-ICD and T-ICD. Methods: The study included 86 patients who received an S-ICD and 1:1 matched to those who received single-chamber T-ICD by gender, age, diagnosis, left ventricular ejection fraction (LVEF), and implant year. The clinical outcomes and implant complications were compared between the two groups. Results: The mean age of the 172 patients was 45 years, and 129 (75%) were male. The most common cardiac condition was hypertrophic cardiomyopathy (HCM, 37.8%). The mean LVEF was 50%. At a mean follow-up of 23 months, the appropriate and inappropriate ICD therapy rate were 1.2% vs. 4.7%(X^2= 1.854, P=0.368) and 9.3% vs. 3.5%(X^2 = 2.428, P = 0.211) in S-ICD and T-ICD groups respectively. There were no significant differences in device-related major and minor complications between the two groups (7.0% vs. 3.5%, X^2 = 1.055, P = 0.496). The S-ICD group had higher T-wave oversensing than T-ICD group (9.3% vs. 0%, X^2 = 8.390, P=0.007). Sixty-five patients had HCM (32 in S-ICD and 33 in T-ICD). The incidence of major complications was not significantly different between the two groups. Conclusions: The efficacy of an S-ICD is comparable to that of T-ICD, especially in a dominantly HCM patient population. The S-ICD is assodated with fewer major complications demanding reoperation.

Main air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillators: A systematic review and meta-analysis

Objective: Previous studies of ambient air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillator (ICD) have yielded mixed results, and the association between air pollution and ventricular arrhythmias in these patients remains unclear. This study aimed to assess and quantify the association between exposure to major air pollutants [CO, inhalable particles (PM10), SO2, fine particulate matter (PM2.5), O3, and NO2] and the presence of ventricular arrhythmia in patients with ICD. Methods: The Medline, PubMed, Web of Science, Global Health Library, Virtual Health Library, Population Information Online (POPLINE), and New York Academy of Medicine Grey Literature Report databases were searched to identify studies analyzing the association between ventricular arrhythmias in patients with ICD and the abovementioned main air pollutants. Pooled estimates were generated using a random-effects model or fixed-effects model, according to the value of heterogeneity. Heterogeneity within studies was assessed using Cochran's Q and I2 statistics. Funnel plots, Egger's regression test, and Begg's rank correlation method were used to evaluate publication bias. Sensitivity analyses were also conducted to evaluate the potential sources of heterogeneity. Results: After a detailed screening of 167 studies, seven separate studies were identified. Ventricular arrhythmias in patients with ICD were found to be positively, but not significantly, associated with CO, PM10, SO2, PM2.5, and NO2, with a pooled estimate [odds ratio (OR) associated with each 10 μg/m3 increase in pollutant concentration, except for CO, which was associated with each 1 mg/m3 increase in concentration] of 1.03 [95％ confidence interval (CI): 0.92-1.17, P = 0.59] for CO, 1.01 (95％CI: 0.97-1.05, P = 0.55) for PM10, 1.09 (95％CI: 0.95-1.24, P = 0.22) for SO2, 1.07 (95％CI: 0.95-1.21, P = 0.25) for PM2.5, and 1.06 (95％CI:0.98-1.14, P = 0.16) for NO2. No increased risk of ventricular arrhythmias in patients with ICD was found to be associated with O3 (OR = 1.00; 95％CI: 0.98-1.01, P = 0.56). Conclusions: The results of this study provide little evidence that ambient air pollutants affect the risk of ICD discharges for treating ventricular arrhythmias.