The serum matrix metalloproteinase-9 level is an independent predictor of recurrence after ablation of persistent atrial fibrillation

OBJECTIVES: This study investigated whether the serum matrix metalloproteinase-9 level is an independent predictor of recurrence after catheter ablation for persistent atrial fibrillation. METHODS: Fifty-eight consecutive patients with persistent atrial fibrillation were enrolled and underwent catheter ablation. The serum matrix metalloproteinase-9 level was detected before ablation and its relationship with recurrent arrhythmia was analyzed at the end of the follow-up. RESULTS: After a mean follow-up of 12.1±7.2 months, 21 (36.2%) patients had a recurrence of their arrhythmia after catheter ablation. At baseline, the matrix metalloproteinase-9 level was higher in the patients with recurrence than in the non-recurrent group (305.77±88.90 vs 234.41±93.36 ng/ml, respectively, p=0.006). A multivariate analysis showed that the matrix metalloproteinase-9 level was an independent predictor of arrhythmia recurrence, as was a history of atrial fibrillation and the diameter of the left atrium. CONCLUSION: The serum matrix metalloproteinase-9 level is an independent predictor of recurrent arrhythmia after catheter ablation in patients with persistent atrial fibrillation

In vivo effects of mid-myocardial pacing on transmural dispersion of repolarization and conduction in canines

In our previous in vitro study mid-myocardial relative to epicardial pacing decreased transmural dispersion of depolarization (TDR) and prevented ventricular arrhythmia. We therefore hypothesized that in vivo mid-myocardial pacing in canines has a similar effect. Using custom-made electrodes, monophasic action potentials were simultaneously recorded in vivo from left ventricular epicardial (Epi), mid-myocardial (Mid) and endocardial (Endo) layers of canines (n = 12). TDR was significantly increased at Epi (44.6 ± 6. 4 ms, 14.2 ± 5.1 ms, and 13.8 ± 5.4 ms for Epi, Mid and Endo pacing, respectively, P < 0.001), and similarly at Mid and Endo pacing (P = 0.855). This result was reproducible after ibutilide administration (n = 12). TDR was augmented at each layer pacing and significantly increased at Epi (78.1 ± 15.9 ms, 46.8 ± 16.0 ms, and 46.5 ± 15.2 ms for Epi, Mid, and Endo pacing, respectively, P < 0.001), but was similar at Endo and Mid pacing (P = 0.965). TDR at 3 cm from left ventricular apex pacing site was similar between Mid and Endo pacing, and still significantly increased at Epi pacing. At 3 cm distance, the first activation myocardium was still the epicardium at Epi, while sequence transformed from mid-myocardium to endocardium at Mid pacing. Mid as compared to Epi pacing significantly decreases TDR and remains this advantage on the distant myocardium away from the pacing site

In vivo effects of mid-myocardial pacing on transmural dispersion of repolarization and conduction in canines

Objective: In our previous in vitro study mid-myocardial relative to epicardial pacing decreased transmural dispersion of depolarization (TDR) and prevented ventricular arrhythmia. We therefore hypothesized that in vivo mid-myocardial pacing in canines has a similar effect. Methods and results: Using custom-made electrodes, monophasic action potentials were simultaneously recorded in vivo from left ventricular epicardial (Epi), mid-myocardial (Mid) and endocardial (Endo) layers of canines (n = 12). TDR was significantly increased at Epi (44.6 ± 6. 4 ms; 14.2 ± 5.1 ms; and 13.8 ± 5.4 ms for Epi, Mid and Endo pacing, respectively; P < 0.001), and similarly at Mid and Endo pacing (P = 0.855). This result was reproducible after ibutilide administration (n = 12). TDR was augmented at each layer pacing and significantly increased at Epi (78.1 ± 15.9 ms; 46.8 ± 16.0 ms; and 46.5 ± 15.2 ms for Epi, Mid, and Endo pacing, respectively; P < 0.001), but was similar at Endo and Mid pacing (P = 0.965). TDR at 3 cm from left ventricular apex pacing site was similar between Mid and Endo pacing, and still significantly increased at Epi pacing. At 3 cm distance, the first activation myocardium was still the epicardium at Epi, while sequence transformed from mid-myocardium to endocardium at Mid pacing. Conclusion: Mid as compared to Epi pacing significantly decreases TDR and remains this advantage on the distant myocardium away from the pacing site

Weight Loss and Tar Evolution during Coal Devolatilization at Various Heating Rates

Temperature-resolved weight loss and tar yield during atmospheric devolatilization of pulverized coal have been obtained on a wire mesh reactor (WMR), which imposes prescribed thermal histories covering a wide range of heating rates on coals from lignite to anthracite. The accuracy of measurements has been improved by diminishing non-isothermality in the sample, ensuring independence of yields on loading density, and the development of a convenient tar collection method that inhibits secondary pyrolysis but also secures capture completeness. We reconfirm the continuous rank effects in terms of reaction dynamics and partitioning between tar and non-condensables but at disparate heating rates of 5 and 1000 K/s. In addition, we depict the constant variation in gas evolution histories among various coals before the cessation of tar release, whereas since the end of tar evolution, variations in gas formation kinetics for different coals gradually shrink with increasing temperatures. A larger fraction of total gases is found expelled after tar evolution by coals of higher rank. The sensitivity of the tar yield to heating rate is maintained the same over the range of 5–1000 K/s but varies with rank, being greatest for lignites and low-volatile bituminous coals but exhibiting a minimum for high-volatile bituminous coals

Depression increases sympathetic activity and exacerbates myocardial remodeling after myocardial infarction: evidence from an animal experiment.

Depression is an independent risk factor for cardiovascular events and mortality in patients with myocardial infarction (MI). Excessive sympathetic activation and serious myocardial remodeling may contribute to this association. The aim of this study was to discuss the effect of depression on sympathetic activity and myocardial remodeling after MI. Wild-type (WT) rats were divided into a sham group (Sham), a myocardial infarction group (MI), a depression group (D), and a myocardial infarction plus depression group (MI+D). Compared with controls, the MI+D animals displayed depression-like behaviors and attenuated body weight gain. The evaluation of sympathetic activity showed an increased level in plasma concentrations of epinephrine and norepinephrine and higher expression of myocardial tyrosine hydroxylase in the MI+D group than the control groups (p<0.05 for all). Cardiac function and morphologic analyses revealed a decreased fractional shortening accompanied by increased left ventricular dimensions, thinning myocardium wall, and reduced collagen repair in the MI+D group compared with the MI group (p<0.05 for all). Frequent premature ventricular contractions, prolonged QT duration and ventricular repolarization duration, shorted effective refractory period, and increased susceptibility to ventricular arrhythmia were displayed in MI+D rats. These results indicate that sympathetic hyperactivation and exacerbated myocardial remodeling may be a plausible mechanism linking depression to an adverse prognosis after MI

The serum matrix metalloproteinase-9 level is an independent predictor of recurrence after ablation of persistent atrial fibrillation

OBJECTIVES: This study investigated whether the serum matrix metalloproteinase-9 level is an independent predictor of recurrence after catheter ablation for persistent atrial fibrillation. METHODS: Fifty-eight consecutive patients with persistent atrial fibrillation were enrolled and underwent catheter ablation. The serum matrix metalloproteinase-9 level was detected before ablation and its relationship with recurrent arrhythmia was analyzed at the end of the follow-up. RESULTS: After a mean follow-up of 12.1±7.2 months, 21 (36.2%) patients had a recurrence of their arrhythmia after catheter ablation. At baseline, the matrix metalloproteinase-9 level was higher in the patients with recurrence than in the non-recurrent group (305.77±88.90 vs 234.41±93.36 ng/ml, respectively, p=0.006). A multivariate analysis showed that the matrix metalloproteinase-9 level was an independent predictor of arrhythmia recurrence, as was a history of atrial fibrillation and the diameter of the left atrium. CONCLUSION: The serum matrix metalloproteinase-9 level is an independent predictor of recurrent arrhythmia after catheter ablation in patients with persistent atrial fibrillation