A new method of building permanent A-V block model: ablating his-bundle potential through femoral artery with pre-implanted biventricular pacemaker.

BACKGROUND: To explore the feasibility of a new method of achieving a permanent A-V block animal model. METHODS: 16 beagles were randomly divided into two groups based on the method of their pre-implanted biventricular pacemakers. (1) In the first group (8 beagles), the A-V block model was achieved by ablating his-bundle potential at the site of the left ventricular superior-septum, under the aortic sinus, through femoral artery. (2) In the second group (8 beagles), the A-V block model was achieved by ablating his-bundle potential at the triangle of Koch, through femoral vein. A complete A-V block model was achieved as a standard in this study. The success rates, intraoperative arrhythmias, operative and X-ray exposure time, intraoperative bleeding amount were assessed in this two groups, both animal models were followed up for four weeks and then fasted to monitor myocardial pathological changes. RESULTS: The success rate of the first group, which with fewer intraoperative arrhythmias, and less operative and X-ray exposure time, was significantly higher than the second group. CONCLUSIONS: Compared with traditional animal method, our new method of ablating his-bundle potential at the left ventricle from the femoral artery has a higher success rate, fewer occurrence of malignant arrhythmias, and less operation and X-ray time. Thus, our new method should be preferred in the building of Permanent A-V Block Model.

Idiopathic premature ventricular contractions and ventricular tachycardias originating from the vicinity of tricuspid annulus: results of radiofrequency catheter ablation in thirty-five patients.

BACKGROUND: In recent years, catheter ablation has increasingly been used for ablation of idiopathic premature ventricular complexes (PVCs) or ventricular tachycardias (IVTs). However, the mapping and catheter ablation of the arrhythmias originating from the vicinity of tricuspid annulus (TA) may not be fully understood. This study aimed to investigate electrophysiologic characteristics and effects of radiofrequency catheter ablation (RFCA) for patients with symptomatic PVCs and IVTs originating from the vicinity of TA. METHODS: Characteristics of body surface electrocardiogram (ECG) and electrophysiologic recordings were analyzed in 35 patients with symptomatic PVCs/ IVTs originating from the vicinity of TA. RFCA was performed using pace mapping and activation mapping. RESULTS: Among the 35 patients with PVCs/IVTs arising from the vicinity of TA, complete elimination of PVCs/IVTs could be achieved by RFCA in 32 patients (success rate 91.43%) during a median follow-up period of 21 months. PVCs/IVTs originating from the vicinity of TA had distinctive ECG characteristics that were useful for identifying the precise origin. An rS pattern was recorded in lead V1 in 93.1% of patients with PVCs/IVTs from the free wall of TA, vs 16.7% of patients with PVCs/IVTs from the septal TA, whereas a QS pattern in lead V1 occurred in 83.3% of patients with PVCs/IVTs from the septal TA vs 6.9% of patients with PVCs from the free wall of the TA. The precordial R wave transition occurred by lead V3 or earlier in all patients with PVCs/IVTs originating from the septal portion of the TA, as compared to transition beyond V3 in all patients with PVCs/IVTs from the free wall of the TA. CONCLUSIONS: RFCA is an effective curative therapy for symptomatic PVCs/IVTs originating from the vicinity of TA. There are specific characteristics in ECG and the ablation site could be located by ECG analysis.

Successful epicardial ablation of idiopathic mitral annular ventricular tachycardia from the great cardiac vein.

This case report describes idiopathic ventricular tachycardia (VT) originating from the anterolateral site of mitral annulus. Radiofrequency (RF) energy application at an endocardial site of mitral annulus could not eliminate the tachycardia. The earliest epicardial activation preceding the onset of the QRS complex by 34 ms was found at the great anterior cardiac vein just opposite to the endocardial ablation catheter, pace mapping provided an identical (12/12) match with the VT morphology at the site, and RF ablation effectively eliminated the VT from the great cardiac vein within the coronary venous system.

Case Report: ALK-Positive Histiocytosis With KIF5B-ALK Fusion in Cerebrum-Disseminated Lesions in a Child.

Background: Anaplastic lymphoma kinase (ALK)-positive histiocytosis is a rare type of histiocytosis that could affect multiple systems in children and adults. 10 cases of ALK-positive histiocytosis invading the central nervous system (CNS) have been reported. Herein, we report a case of ALK-positive histiocytosis invading the central nervous system and lungs and the details of follow-up of tumor dynamic changes during treatment. Case Presentation: An 18-month-old boy was underweight and had slow growth of almost 3 months duration. The child could not stand and walk independently, and his language and intelligence development occurred later than those of his peers. Cranial magnetic resonance imaging revealed a giant suprasellar lesion with isosignal, measuring approximately 5.1× 3.6× 4.0 cm on T1-weighted imaging, with an obvious mass effect. Nodular, slightly low-signal shadows were also observed in the left temporal pole and left hippocampus, measuring approximately 1.0 cm × 0.7 cm× 0.5 cm and 0.9 cm× 0.8 cm × 0.5 cm on T1-weighted, respectively. The child underwent partial resection of the suprasellar lesion, and a diagnosis of ALK-positive histiocytosis was made histologically. Subsequently, the patient received chemotherapy (CHOP regimen) and anti-ALK therapy (crizotinib). The lesions were gradually shrinking without dissemination and the changes of intracranial and lung lesions were monitored with imaging during therapy. Unfortunately, the child died 8 months after the first surgery because of worsening intracranial infection. Conclusion: ALK-positive histiocytosis may involve the central nervous system and disseminate intracranially. ALK-positive histiocytosis should be considered for the differential diagnosis of suprasellar lesions.

Bone Mineral Density Assessment by Quantitative Computed Tomography in Glucocorticoid-Treated Boys With Duchenne Muscular Dystrophy: A Linear Mixed-Effects Modeling Approach.

Objective: Boys with Duchenne muscular dystrophy (DMD) are at risk of bone damage and low bone mineral density (BMD). The aim of the study is to examine lumbar BMD values measured by QCT and identify the factors associated with BMD loss using a multilevel mixed-effects model. Methods: Lumbar BMD was evaluated by quantitative computed tomography (QCT) at diagnosis, 1 and 2 years follow up in patients with DMD who were treated with GC. Demographic data, functional activity scores (FMSs), laboratory parameters and steroid use were recorded. A multilevel mixed-effects model was used to analyze BMD loss. Results: Nineteen patients with DMD who had a total of sixty complete records between January 2018 and October 2021 were retrospectively analyzed. At baseline, 15.8% of patients (3/19) had low lumbar BMD (Z score ≤ -2), and the mean BMD Z score on QCT was -0.85 (SD 1.32). The mean BMD Z score at 1 and 2 years postbaseline decreased to -1.56 (SD 1.62) and -2.02 (SD 1.36), respectively. In our model, BMD Z score loss was associated with age (ß=-0.358, p=0.0003) and FMS (ß=-0.454, p=0.031). Cumulative GC exposure and serum levels of calcium, phosphorus, 25(OH)-vitamin D and creatinine kinase did not independently predict BMD loss. Conclusions: This study demonstrates that in DMD patients, lumbar BMD decreased gradually and progressively. Age and FMS are the main contributors to BMD loss in boys with DMD. Early recognition of risk factors associated with BMD loss may facilitate the development of strategies to optimize bone health.

Premature ventricular contractions originating from the left ventricular septum: results of radiofrequency catheter ablation in twenty patients.

BACKGROUND: RFCA has been established as an effective and curative therapy for severely symptomatic PVC from the outflow tract in structurally normal hearts. However, it is unknown whether PVCs originating from the left ventricular septum, are effectively eliminated by RFCA. This study aimed to investigate electrophysiologic characteristics and effects of radiofrequency catheter ablation (RFCA) for patients with symptomatic premature ventricular contraction (PVC) originating from the left ventricular septum without including fascicular PVCs. METHODS: Characteristics of body surface electrocardiogram (ECG) and electrophysiologic recordings endocardiogram in a successful RFCA target were analyzed in 20 patients with symptomatic PVCs originating from the left ventricular septum. RFCA was performed using pace mapping and activation mapping. RESULTS: The QRS morphology of PVCs originating from the left ventricular septum is similar to that seen in fascicular tachycardia. Most of the PVCs originated from the left septum appears in the form of ventricular parasystole. The incidence of ventricular parasystole was 70%. Sustained ventricular tachycardia was not inducible by electrical stimulation and isoproterenol infusion in all 20 patients, ablation at the site recording the earliest Purkinje potential was not effective in all 20 patients, and Purkinje potentials were not identified at successful sites during point mapping. Sixteen patients were successful with RFCA using pace mapping and activation mapping, 3 failed, and 1 recurrent. CONCLUSION: Although the ECG characteristics of the PVCs arising from the left ventricular septum are similar to that seen in fascicular tachycardia, the electrophysiologic characteristics are different between the two types of PVCs. The distinguishing characteristic of the PVCs is that Purkinje potentials were not present at the site of successful ablation, suggesting a myocardial as opposed to fascicular substrate. RFCA is an effective curative therapy for symptomatic PVCs originating from the left ventricular septum (not from the left anterior and posterior fascicle).

R/S Ratio in Lead III Predicts Successful Ablation of Ventricular Arrhythmias Originating in Para-Hisian Region.

OBJECTIVES: The aim of this study was to investigate the electrocardiographic characteristics of ventricular arrhythmias (VAs) originating near the His bundle (HB) and use the R/S ratio in lead III (RIII/SIII ratio) to predict successful ablation of para-Hisian VAs. BACKGROUND: Catheter ablation for idiopathic VAs near the HB is often challenging, and data are limited. METHODS: The present study included 134 consecutive patients undergoing catheter ablation of para-Hisian VAs. The electrocardiographic characteristics in these patients were retrospectively evaluated with successful ablation and failed ablation. RESULTS: Successful ablation was achieved in 115 (85.8%) of the 134 patients. There was no significant difference in QRS duration between the successful and the failed ablation groups. The ablation success rate was significantly lower for para-Hisian VAs with a predominantly positive R wave in lead III than those with a predominantly negative S wave in lead III. The significant factor associated with successful ablation was the RIII/SIII ratio. The RIII/SIII ratio ≤1.1 predicted the successful ablation of para-Hisian VAs with high sensitivity (80.9%) and specificity (94.7%). The RIII/SIII ratio of >1.2 had high sensitivity (100.0%) and specificity (82.8%) to predict the distance <5 mm from the site of origin of para-Hisian VAs to the site recording the largest HB potential. CONCLUSIONS: The RIII/SIII ratio was a helpful predictor of the successful ablation of VAs originating in the vicinity of the HB. This may be useful for planning ablation of para-Hisian VAs and minimizing the risk of inadvertent atrioventricular block.

Establishment of a canine model of cardiac memory using endocardial pacing via internal jugular vein.

BACKGROUND: Development of experimental animal models has played an important role in understanding the mechanisms of cardiac memory. The purpose of this study was to evaluate a new canine model of cardiac memory using endocardial ventricular pacing via internal jugular vein. METHODS: Twelve Beagle dogs underwent placement of a permanent ventricular pacemaker mimicking the use of pacemakers in humans and induction of cardiac memory by endocardial ventricular pacing. RESULTS: Cardiac memory was achieved in 11 of 12 attempts overall. Procedural mortality due to cardiac tamponade (n = 1) occurred in the first attempt. The T-wave memory persisted for 96 +/- 17 minutes and 31 +/- 6 days in the short-term and long-term cardiac memory groups, respectively. There were no significant differences in the heart rate, blood pressure and echocardiographic parameters in the animals between before and after ventricular pacing in the short-term and long-term cardiac memory groups. No significant pathologic changes with the light microscopy were found in the present study in all dogs. CONCLUSION: The model does require surgery but is not as invasive as an open-chest model. This canine model can serve as a useful tool for studying mechanisms of cardiac memory.

Corrigendum: Ivabradine Treatment Reduces Cardiomyocyte Apoptosis in a Murine Model of Chronic Viral Myocarditis.

[This corrects the article DOI: 10.3389/fphar.2018.00182.].

The cholinergic anti-inflammatory pathway ameliorates acute viral myocarditis in mice by regulating CD4+ T cell differentiation.

Many studies have found that abnormalities in the proportion and differentiation of CD4+ T cells (Th cells) are closely related to the pathogenesis of viral myocarditis (VMC). Our previous research indicates that the cholinergic anti-inflammatory pathway (CAP) attenuates the inflammatory response of VMC and downregulates the expression of cytokines in Th1 and Th17 cells. This suggests that the cholinergic anti-inflammatory pathway likely attenuates the inflammatory response in VMC by altering Th cell differentiation. The aim of this study is to investigate the effect of CAP on CD4+ T cell differentiation in VMC mice. CD4+ T cells in the spleen of VMC mice were obtained and cultured in the presence of nicotine or methyllycaconitine (MLA). Cells were harvested and analyzed for the percentage of each Th cell subset by flow cytometry and transcription factor release by Western blot. Then, we detected the effect of CAP on the differentiation of Th cells in vivo. Nicotine or MLA was used to activate and block CAP, respectively, in acute virus-induced myocarditis. Nicotine treatment increased the proportion of Th2 and Treg cells, decreased the proportion of Th1 and Th17 cells in the spleen, reduced the level of proinflammatory cytokines, and attenuated the severity of myocardium lesions and cellular infiltration in viral myocarditis. MLA administration had the opposite effect. Our result demonstrated that CAP effectively protects the myocardium from virus infection, which may be attributable to the regulation of Th cell differentiation.

Ivabradine Treatment Reduces Cardiomyocyte Apoptosis in a Murine Model of Chronic Viral Myocarditis.

This study was designed to explore the effects of ivabradine on cardiomyocyte apoptosis in a murine model of chronic viral myocarditis (CVMC). Mice were inoculated intraperitoneally with Coxsackievirus B3 at days 1, 14, and 28, respectively. On day 42, the mice were gavaged with ivabradine for 30 days until the 72nd day. The heart of infected mice was dilated and a large number of interstitial fibroblasts infiltrated into the myocardium on day 42. Compared with the untreated CVMC mice, mice treated with ivabradine showed a significant reduction in heart rate and less impairment of left ventricular function on day 72. The positive apoptosis of myocardial cells in the untreated CVMC group was significantly higher than that of the normal group and was significantly reduced after treatment with ivabradine. The expression levels of Bax and Caspase-3 in the untreated CVMC group were significantly higher than those of the normal group and were apparently reduced in the ivabradine-treated group versus the untreated CVMC group. Bcl-2 showed a high expression in the normal group and low expression in the untreated CVMC group, but its expression level in the ivabradine-treated group were higher than that of the untreated CVMC group. These results indicate that ivabradine could attenuate the expression of Caspase-3 by downregulation of Bax and upregulation of Bcl-2 to prevent the deterioration of cardiac function resulting from ventricular myocyte loss by cardiomyocyte apoptosis.

Right Cervical Vagotomy Aggravates Viral Myocarditis in Mice Via the Cholinergic Anti-inflammatory Pathway.

The autonomic nervous system dysfunction with increased sympathetic activity and withdrawal of vagal activity may play an important role in the pathogenesis of viral myocarditis. The vagus nerve can modulate the immune response and control inflammation through a 'cholinergic anti-inflammatory pathway' dependent on the α7-nicotinic acetylcholine receptor (α7nAChR). Although the role of ß-adrenergic stimulation on viral myocarditis has been investigated in our pervious studies, the direct effect of vagal tone in this setting has not been yet studied. Therefore, in the present study, we investigated the effects of cervical vagotomy in a murine model of viral myocarditis. In a coxsackievirus B3 murine myocarditis model (Balb/c), effects of right cervical vagotomy and nAChR agonist nicotine on echocardiography, myocardial histopathology, viral RNA, and proinflammatory cytokine levels were studied. We found that right cervical vagotomy inhibited the cholinergic anti-inflammatory pathway, aggravated myocardial lesions, up-regulated the expression of TNF-α, IL-1ß, and IL-6, and worsened the impaired left ventricular function in murine viral myocarditis, and these changes were reversed by co-treatment with nicotine by activating the cholinergic anti-inflammatory pathway. These results indicate that vagal nerve plays an important role in mediating the anti-inflammatory effect in viral myocarditis, and that cholinergic stimulation with nicotine also plays its peripheral anti-inflammatory role relying on α7nAChR, without requirement for the integrity of vagal nerve in the model. The findings suggest that vagus nerve stimulation mediated inhibition of the inflammatory processes likely provide important benefits in myocarditis treatment.

Dynamic Changes of QRS Morphology of Premature Ventricular Contractions During Ablation in the Right Ventricular Outflow Tract: A Case Report.

Electrocardiographic characteristics can be useful in differentiating between right ventricular outflow tract (RVOT) and aortic sinus cusp (ASC) ventricular arrhythmias. Ventricular arrhythmias originating from ASC, however, show preferential conduction to RVOT that may render the algorithms of electrocardiographic characteristics less reliable. Even though there are few reports describing ventricular arrhythmias with ASC origins and endocardial breakout sites of RVOT, progressive dynamic changes in QRS morphology of the ventricular arrhythmias during ablation obtained were rare.This case report describes a patient with symptomatic premature ventricular contractions of left ASC origin presenting an electrocardiogram (ECG) characteristic of right ventricular outflow tract before ablation. Pacing at right ventricular outflow tract reproduced an excellent pace map. When radiofrequency catheter ablation was applied to the right ventricular outflow tract, the QRS morphology of premature ventricular contractions progressively changed from ECG characteristics of right ventricular outflow tract origin to ECG characteristics of left ASC origin.Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the left ASC. The distance between the successful ablation site of the left ASC and the site with an excellent pace map of the RVOT was 20 mm.The ndings could be strong evidence for a preferential conduction via the myocardial bers from the ASC origin to the breakout site in the right ventricular outflow tract. This case demonstrates that ventricular arrhythmias with a single origin and exit shift may exhibit QRS morphology changes.

Catheter ablation of idiopathic premature ventricular contractions and ventricular tachycardias originating from the vicinity of endocardial and epicardial mitral annulus.

BACKGROUND: Several previous reports have revealed that idiopathic ventricular arrhythmias (VAs), including premature ventricular contractions (PVCs) and ventricular tachycardias (IVTs), can originate from endocardial mitral annulus (ENDO MA). However, these data are limited to ENDO MA VAs, and little is known about the electrocardiographic (ECG) characteristics and the efficacy of radiofrequency catheter ablation (RFCA) via the coronary venous system for the VAs arising from the epicardial MA (EPI MA). METHODOLOGY/PRINCIPAL FINDINGS: Characteristics of body surface electrocardiogram and electrophysiologic recordings were analyzed in 21 patients with symptomatic PVCs/IVTs originating from the vicinity of MA. Among 597 patients with PVCs/IVTs, the incidence of VAs originating from the ENDO and EPI MA was 3.52% (21 cases). Eleven (52%) from the ENDO MA, and 10 (48%) from the EPI MA. There were different characteristics of ECG of PVCs/VT originating from the ENDO and EPI MA. The prolonged pseudodelta wave time and intrinsicoid deflection time in lead V2 and the precordial maximum deflection index reliably differentiated EPI MA VAs from ENDO MA VAs with high sensitivity and specificity. Successful RFCA in 18 patients could be achieved (85.7% acute procedural success). CONCLUSIONS/SIGNIFICANCE: ECG characteristics of PVCs/VTs originating from the different portions of the MA are different, and can help regionalize the origin of these arrhythmias. RFCA within the coronary venous system was relatively effective and safe for the PVCs/IVTs and should be seen as an alternative approach, when the MA PVCs/IVTs could not be eliminated by RFCA from the endocardium.

Catheter ablation of idiopathic premature ventricular contractions and ventricular tachycardias originating from right ventricular septum.

BACKGROUND: Idiopathic premature ventricular contractions (PVCs) and ventricular tachycardias (IVTs) originating from the subtricuspid septum and near the His bundle have been reported. However, little is known about the prevalence, distribution, electrocardiographic characteristics and the efficacy of radiofrequency catheter ablation (RFCA) for the ventricular arrhythmias arising from the right ventricular (RV) septum. This study aimed to investigate electrocardiographic characteristics and effects of RFCA for patients with symptomatic PVCs/IVTs, originating from the different portions of the RV septum. METHODOLOGY/PRINCIPAL FINDINGS: Characteristics of body surface electrocardiogram and electrophysiologic recordings were analyzed in 29 patients with symptomatic PVCs/IVTs originating from the RV septum. Among 581 patients with PVCs/IVTs, the incidence of ventricular arrhythmias originating from the RV septum was 5%. Twenty (69%) had PVCs/IVTs from the septal portion of the tricuspid valvular RV region (3 from superoseptum, 15 from midseptum, 2 from inferoseptum), and 9 (31%) from the septal portion of the basal RV (1 from superoseptum, 4 from midseptum, 4 from inferoseptum). There were different characteristics of ECG of PVCs/VT originating from the different portions of the RV septum. Twenty-seven of 29 patients with PVCs/IVTs arising from the RV septum were successfully ablated (93.1% acute success). CONCLUSIONS/SIGNIFICANCE: ECG characteristics of PVCs/VTs originating from the different portions of the RV septum are different, and can help regionalize the origin of these arrhythmias. The septal portion of the tricuspid valvular RV region was the preferential site of origin. RFCA was effective and safe for the PVCs/IVTs arising from the RV septum.

The mechanism of carvedilol in experimental viral myocarditis.

Carvedilol is a nonselective ß-blocker with α1-adrenergic blocking and antioxidant properties. A number of preclinical experiments and clinical trials have demonstrated that carvedilol provides prominent benefit in heart failure. However, less research has been done in the area of animal models of viral myocarditis. This paper reviews the use of carvedilol in animal models of viral myocarditis. The experimental evidence strongly suggests that carvedilol, but not metoprolol (a selective ß1-adrenergic blocking agent), protects against viral myocarditis and the superior cardioprotection effect of carvedilol to metoprolol may be due to its upregulating the production of antiinflammatory cytokines, downregulating the production of proinflammatory cytokines, antioxidative effects, the suppression of matrix metalloproteinases production, and positive hemodynamic effects.

Comparison of effects of ivabradine versus carvedilol in murine model with the Coxsackievirus B3-induced viral myocarditis.

BACKGROUND: Elevated heart rate is associated with increased cardiovascular morbidity. The selective I(f) current inhibitor ivabradine reduces heart rate without affecting cardiac contractility, and has been shown to be cardioprotective in the failing heart. Ivabradine also exerts some of its beneficial effects by decreasing cardiac proinflammatory cytokines and inhibiting peroxidants and collagen accumulation in atherosclerosis or congestive heart failure. However, the effects of ivabradine in the setting of acute viral myocarditis and on the cytokines, oxidative stress and cardiomyocyte apoptosis have not been investigated. METHODOLOGY/PRINCIPAL FINDINGS: The study was designed to compare the effects of ivabradine and carvedilol in acute viral myocarditis. In a coxsackievirus B3 murine myocarditis model (Balb/c), effects of ivabradine and carvedilol (a nonselective ß-adrenoceptor antagonist) on myocardial histopathological changes, cardiac function, plasma noradrenaline, cytokine levels, cardiomyocyte apoptosis, malondialdehyde and superoxide dismutase contents were studied. Both ivabradine and carvedilol similarly and significantly reduced heart rate, attenuated myocardial lesions and improved the impairment of left ventricular function. In addition, ivabradine treatment as well as carvedilol treatment showed significant effects on altered myocardial cytokines with a decrease in the amount of plasma noradrenaline. The increased myocardial MCP-1, IL-6, and TNF-α. in the infected mice was significantly attenuated in the ivabradine treatment group. Only carvedilol had significant anti-oxidative and anti-apoptoic effects in coxsackievirus B3-infected mice. CONCLUSIONS/SIGNIFICANCE: These results show that the protective effects of heart rate reduction with ivabradine and carvedilol observed in the acute phase of coxsackievirus B3 murine myocarditis may be due not only to the heart rate reduction itself but also to the downregulation of inflammatory cytokines.

Evaluation of Safety and Efficacy of Qinming8631 DR Implantable Cardiac Pacemaker in Chinese Patients: A Prospective, Multicenter, Randomized Controlled Trial of the First Domestically Developed Pacemaker of China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>High cost of imported pacemakers is a main obstacle for Chinese patients suffering from bradyarrhythmia, and a domestically developed pacemaker will help lower the burden. This study aimed to evaluate the safety and efficacy of Qinming8631 DR (Qinming Medical, Baoji, China), the first domestically developed dual-chamber pacemaker of China, compared with a commercially available pacemaker Talos DR (Biotronik, Berlin, Germany) in Chinese patients.</p><p><b>METHODS</b>A prospective randomized trial was conducted at 14 centers in China. Participants were randomized into trial (Qinming8631 DR) and control (Talos DR) groups. Parameters of the pacing systems were collected immediately after device implantation and during follow-ups. The effective pacing rate at 6-month follow-up was recorded as the primary end point. Electrical properties, magnet response, single- and double-pole polarity conversion, rate response function, and adverse events of the pacing system were analyzed. The Cochran-Mantel-Haenszel Chi-square test, paired t-test, and Wilcoxon signed-rank test were used for measuring primary qualitative outcomes and comparing normally and abnormally distributed measurement data.</p><p><b>RESULTS</b>A total of 225 patients with a diagnosis of bradyarrhythmia and eligible for this study were randomly enrolled into the trial (n = 113) and control (n = 112) groups. They underwent successful pacemaker implantation with acceptable postoperative pacing threshold and sensitivity. Effective pacing rates of trial and control groups were comparable both in the full analysis set and the per protocol set (81.4% vs. 79.5%, P = 0.712 and 95.4% vs. 89.5%, P = 0.143, respectively). In both data sets, noninferiority of the trial group was above the predefined noninferiority limit(-9.5%).</p><p><b>CONCLUSIONS</b>This study established the noninferiority of Qinming8631 DR to Talos DR. The safety and efficacy of Qinming8631 DR pacemaker were comparable to those of Talos DR in treating patients with cardiac bradyarrhythmia.</p>