Objective: To study the effects of acute cold stress on connexin43 (Cx43) protein expression with drug intervention, and cell to cell conduction with its mechanism in neonatal rats’ myocardial cells.
Methods: The primary neonatal rats’ myocardial cell culture was conducted in 4 groups. Group① , the cells were normally cultured, Group②, the cells were cultured at 4℃, Group③, the cells were cultured at 0℃and Group④, the anti-arrhythmia peptide (AAP 10) was added in Group②and Group③. The apoptosis rate of myocardial cells was evaluated by lfow cytometry assay, mRNA and protein expressions of CX43 were examined by RT-PCR and Western blot analysis, and CX43 phosphorylation product (P-CX43) was detected.
Results: Compared with normally cultured cells, the myocardial cell apoptosis rate was obviously increased by acute cold stress at 4℃and 0℃with time extension. The mRNA expression of Cx43 was decreased at varying degrees at 4℃and 0℃stimulation, the protein expression of Cx43 was decreased at varying degrees at 4℃and 0℃stimulation with time extension, and P-Cx43 level was decreased. While the APP 10 intervention may obviously elevate the protein levels of Cx43 and P-Cx43.
Conclusion: Acute cold stress could reduce the protein expression of CX43 and P-CX43, while APP 10 intervention may elevate such expression and improve the cell to cell conduction in neonatal rats’ myocardial cells.

Objectives:To explore the association between the r'wave amplitude in lead V1 and impedance changes with left bundle branch pacing electrode implantation depth. Methods:A total of 78 patients with normal heart structure and underwent left bundle branch area pacing(LBBAP)in the Second Affiliated Hospital of Nanchang University from January 1,2019 to December 31,2021 were included in this retrospective analysis.Baseline data,intraoperative and imaging data,and 3,6,9 and 12 months of follow-up results were collected.Correlation and regression analysis were performed to define the feasibility using the r'wave in lead V1 during pacing and impedance changes to estimate the electrode depth. Results:r'waves at the end of the QRS complex in lead V1 during pacing were found in 70 cases(89.7%),and 8 cases(10.3%)showed rS,RS type QRS waves,or no r'wave at the end.Correlation analysis showed that r'wave amplitude was positively correlated with electrode depth(r=0.424,P<0.01),negatively correlated with impedance(r=-0.256,P=0.03).There was no significant statistical correlation between electrode implantation depth and impedance(r=-0.132,P=0.27).Regression analysis found that electrode depth was an important factor affecting r'wave amplitude(regression coefficient=0.056,P=0.000).Combined with the established regression model and impedance,it was found that the amplitude of the r'wave in lead V1 is at the range of 0.24-0.69 mV,and the impedance ranges from 648.30 to 828.90 Ω,and the electrode implantation depth is 6-11 mm,which is most suitable.The risk of perforation is low,and the left bundle branch can be successfully captured with a high probability.The pacing parameters are satisfactory,and the pacing QRS wave duration is narrow.During the intraoperative,postoperative 48 hours,and 12-month follow-up period,the patient did not experience complications such as electrode perforation,thromboembolism,cardiac tamponade,infection,or wire dislocation. Conclusions:Left bundle branch region pacing is a safe and feasible pacing method.During LBBAP,the amplitude of the r'wave in lead V1 at the range of 0.24-0.69 mV,and the impedance ranges from 648.30 to 828.90 Ω can be used to guide the pacing in the left bundle branch region and reduce the risk of electrode perforation.

Objective: To evaluate the efficacy and safety of nifekalan (NIF) on cardioversion in atrial fibrillation (AF) patients post radiofrequency ablation, and investigate the relevant factors related to the cardioversion efficacy of NIF. Methods: We screened patients with sustained AF rhythm after radiofrequency ablation between November 2016 and July 2018. Participants were treated with intravenous NIF 0.4 mg/kg within 5-10 minutes after ablation. We observed the adverse reaction, and monitored the rhythm, heart rate, QT interval and QTc interval before the medication and at 5, 10, 20, 120 min after the medication. According to the drug outcome of NIF, patients were divided into conversion group and non-conversion group, related factors affecting conversion efficacy were evaluated using logistic regression analysis. Results: (1)A total of 116 patients were enrolled in the study (63 males and 53 females, mean age was (64±18) years). Among them, 72 patients were converted to sinus rhythm, and the overall successful rate was 62.1%. There were 84 patients with persistent AF, of which 50 cases (59.2%) were restored to sinus rhythm. There were 32 patients with paroxysmal AF, 22 cases (68.8%) of them were restored to sinus rhythm. The conversion time was 1.5 to 12 (6.8±3.4)min. (2) In 116 patients, the QT interval and QTc interval were significantly longer after medication than before the drug administration (P<0.01), and peaked at about 10th min, and restored to the level before drug administration at about 120th min. (3) There were 8 cases of bradycardia (6.9%), 3 cases of frequent and short ventricular tachycardia (2.6%). (4) The duration of atrial fibrillation was shorter and left atrial diameter was smaller in the cardioversion group than in the non-cardioversion group (both P<0.05). There were no significant differences in gender, disease history, atrial fibrillation type and structural heart disease between the two groups (P>0.05). (5) Multifactorial logistic regression analysis showed that the duration of atrial fibrillation (OR=0.980, 95%CI 0.966-0.994, P=0.004) and the left atrial diameter (OR=0.888, 95%CI 0.814-0.967, P=0.007) were the factors that influence the cardioversion efficacy of NIF on atrial fibrillation post ablation. Conclusions The total effective rate of NIF was 62.1% in patients witrh sustained AF post radiofrequency ablation, was 68.8% in patients with paroxysmal AF. Besides, NIF has the advantage of short conversion time and few adverse reactions. Left atrium diameter and AF duration were relevant factors that influence the efficacy of NIF of cardioversion in patients with sustained AF after radiofrequency ablation.

Objective To evaluate the efficacy and safety of nifekalan (NIF) on cardioversion in atrial fibrillation (AF) patients post radiofrequency ablation, and investigate the relevant factors related to the cardioversion efficacy of NIF. Methods We screened patients with sustained AF rhythm after radiofrequency ablation between November 2016 and July 2018. Participants were treated with intravenous NIF 0.4 mg/kg within 5-10 minutes after ablation. We observed the adverse reaction, and monitored the rhythm, heart rate, QT interval and QTc interval before the medication and at 5, 10, 20, 120 min after the medication. According to the drug outcome of NIF, patients were divided into conversion group and non?conversion group, related factors affecting conversion efficacy were evaluated using logistic regression analysis. Results (1)A total of 116 patients were enrolled in the study (63 males and 53 females, mean age was (64±18) years). Among them, 72 patients were converted to sinus rhythm, and the overall successful rate was 62.1%. There were 84 patients with persistent AF, of which 50 cases (59.2%) were restored to sinus rhythm. There were 32 patients with paroxysmal AF, 22 cases (68.8%) of them were restored to sinus rhythm. The conversion time was 1.5 to 12 (6.8±3.4)min. (2) In 116 patients, the QT interval and QTc interval were significantly longer after medication than before the drug administration (P<0.01), and peaked at about 10th min, and restored to the level before drug administration at about 120th min. (3) There were 8 cases of bradycardia (6.9%), 3 cases of frequent and short ventricular tachycardia (2.6%). (4) The duration of atrial fibrillation was shorter and left atrial diameter was smaller in the cardioversion group than in the non?cardioversion group (both P<0.05). There were no significant differences in gender, disease history, atrial fibrillation type and structural heart disease between the two groups (P>0.05). (5) Multifactorial logistic regression analysis showed that the duration of atrial fibrillation ( OR=0.980, 95%CI 0.966-0.994, P=0.004) and the left atrial diameter ( OR=0.888, 95%CI 0.814-0.967, P=0.007) were the factors that influence the cardioversion efficacy of NIF on atrial fibrillation post ablation. Conclusions The total effective rate of NIF was 62.1% in patients witrh sustained AF post radiofrequency ablation, was 68.8% in patients with paroxysmal AF. Besides, NIF has the advantage of short conversion time and few adverse reactions. Left atrium diameter and AF duration were relevant factors that influence the efficacy of NIF of cardioversion in patients with sustained AF after radiofrequency ablation.