His bundle pacing versus right ventricular pacing: A comparative study.

BACKGROUND: Pacing is the most effective and dependable method for treating complete atrioventricular block (AVB). OBJECTIVE: The purpose of this study is to investigate the use of His bundle pacing (HBP) in patients with atrioventricular block. METHODS: Patients who underwent HBP or right ventricular pacing (RVP) were enrolled and divided into two groups: the HBP group and the RVP group, respectively. We compared baseline clinical data, fluoroscopy duration, operation duration, pacing electrode parameters during the operation or follow-up, baseline QRS duration, and pacing QRS duration. RESULTS: HBP was attempted in 48 patients and was successful in 34 patients who were included in the HBP group. In addition, 30 RVP patients were included in the RVP group. Fluoroscopy duration and operation duration were significantly longer in the HBP group compared to the RVP group. Compared to the RVP group, the HBP group had a higher pacing threshold, a lower R wave amplitude, and a shorter pacing QRS duration. At 6 months of follow-up, the pacing threshold remained higher, the R wave amplitude was significantly lower, and the end-diastolic diameter of the left ventricle was smaller in the HBP group. CONCLUSION: HBP was safe and effective for atrioventricular block despite the longer fluoroscopy and operation duration in the HBP group when compared to the RVP group.

[Effect of Microbial Community Structure and Metabolites on Sludge Settling Ability Under Three Different Switching Condition Processes].

Using sodium acetate as the carbon source, sludge settling ability (settleability) was investigated under three processes:AAO nitrogen and phosphorus removal(process Ⅰ), AO nitrification-denitrification (process Ⅱ), and aerobic carbon removal (process Ⅲ). The succession of microbial community structures in sludge was traced, the content and composition of microbial metabolites were monitored, and the effects of operational mode on sludge settleability were analyzed. The results showed that the settleability of process Ⅰ was the best, followed by process Ⅲ and Ⅱ. Under the different operating conditions, the dominant bacteria and microbial community structure of the system changed significantly. The relative amount of Thiothrix was the dominant bacteria affecting the sludge settleability. The abundances of Thiothrix were only 0.08% and 1.51% with fresh sludge and in process Ⅰ; this abundance increased to 9.41% in process Ⅱ and decreased to 4.29% in process Ⅲ. The anaerobic zone of process I had an inhibitory effect on the growth of the bacterium, while the anoxic zone of process Ⅱ stimulated its dominant growth. At the same time, comparison showed that the microbial population diversity was highest in process Ⅰ. followed by processes Ⅱ and Ⅲ. The introduction of anoxic and anaerobic zones led to the increase of system function and environmental complexity, and increased microbial community diversity. Analyses of extracellular polymeric substances (EPS) and fluorescence characteristics showed that the changes in microbial community structure had a significant effect on the composition and content of EPS, which aggravated the process of improving or deteriorating settleability. The sludge settleability was found to be positively correlated with the ratio of protein and polysaccharide in loosely bound EPS.