Transcriptomic analysis of epicardial adipose tissue reveals the potential crosstalk genes and immune relationship between type 2 diabetes mellitus and atrial fibrillation.

BACKGROUND: The complex relationship between atrial fibrillation (AF) and type 2 diabetes mellitus (T2DM) suggests a potential role for epicardial adipose tissue (EAT) that requires further investigation. This study employs bioinformatics and experimental approaches to clarify EAT's role in linking T2DM and AF, aiming to unravel the biological mechanisms involved. METHOD: Bioinformatics analysis initially identified common differentially expressed genes (DEGs) in EAT from T2DM and AF datasets. Pathway enrichment and network analyses were then performed to determine the biological significance and network connections of these DEGs. Hub genes were identified through six CytoHubba algorithms and subsequently validated biologically, with further in-depth analyses confirming their roles and interactions. Experimentally, db/db mice were utilized to establish a T2DM model. AF induction was executed via programmed transesophageal electrical stimulation and burst pacing, focusing on comparing the incidence and duration of AF. Frozen sections and Hematoxylin and Eosin (H&E) staining illuminated the structures of the heart and EAT. Moreover, quantitative PCR (qPCR) measured the expression of hub genes. RESULTS: The study identified 106 DEGs in EAT from T2DM and AF datasets, underscoring significant pathways in energy metabolism and immune regulation. Three hub genes, CEBPZ, PAK1IP1, and BCCIP, emerged as pivotal in this context. In db/db mice, a marked predisposition towards AF induction and extended duration was observed, with HE staining verifying the presence of EAT. Additionally, qPCR validated significant changes in hub genes expression in db/db mice EAT. In-depth analysis identified 299 miRNAs and 33 TFs as potential regulators, notably GRHL1 and MYC. GeneMANIA analysis highlighted the hub genes' critical roles in stress responses and leukocyte differentiation, while immune profile correlations highlighted their impact on mast cells and neutrophils, emphasizing the genes' significant influence on immune regulation within the context of T2DM and AF. CONCLUSION: This investigation reveals the molecular links between T2DM and AF with a focus on EAT. Targeting these pathways, especially EAT-related ones, may enable personalized treatments and improved outcomes.

[Dynamic comparisons of epicardial electrograms between the left atrium and pulmonary veins in atrial fibrillation in goat model].

Objective: To compare epicardial electrograms between the left atrium (LA) and pulmonary veins (PVs) dynamically at development of persistent atrial fibrillation(AF) in goats PVs. Methods: Ten female goats were instrumented with electrodes at the LA and left side PV. Sustained AF (＞24 h) was induced in the goat by rapid intermittent left atrial pacing for(9.5±2.3)days at a pacing interval of 20 ms for 1 s with a maximum output of 6.0 V, followed by a 2-s period without pacing. Characteristics of PVs and LA epicardial electrograms were analyzed in the development of AF. Results: With prolonged stimulation, the duration of AF was prolonged, complex fractionated atrial electrograms(CFAEs) in LA and was increased gradually, PVs had more CFAEs than LA all the time. When induced AF lasted for more than 24 h, CFAEs in PVs became sustained approximately (2.7%±3.6% vs 92.6%±6.4%, at onset of AF vs AF lasted for more than 24 h, P＜0.05), and the ratio of CFAEs in PVs was more than that in LA (92.6%±6.4% vs 72.8%±5.3%, P＜0.05). Conclusion: The epicardial CFAEs are in specific area, which increase along with electrical remodeling. The epicardial CFAEs may play an important role in the maintenance of AF in this model.

Amplitude reduction of autonomic nerve function is correlated with ablation lesion quality in patients with paroxysmal atrial fibrillation.

OBJECTIVE: Circumferential pulmonary vein isolation (CPVI) is a common procedure that is performed on patients with atrial fibrillation (AF). However, AF may recur in some patients after treatment. This study assesses the association between autonomic modulation and late recurrence after CPVI and between autonomic modulation and ablation lesion quality. METHODS: We prospectively enrolled 72 patients with paroxysmal AF who underwent CPVI from January 2017 to January 2018. Pre- and post-ablation 24 h electrocardiograms were performed to document heart rate variability (HRV), which represents cardiac autonomic function. The intraablation force-time integral (FTI) was used to indicate the extent of ablation injury. Patients were followed up for 12 months after the procedure and cases of AF recurrence were recorded. RESULTS: Changes in HRV decreased after the procedure, which was correlated with FTI (ΔSDNN: r = -0.26, P = 0.03; ΔrMMSD: r = -0.28, P = 0.02; ΔlnHF: r = -0.22, P = 0.04; ΔLnLF: r = -0.29, P = 0.01). Patients without AF recurrence had more pronounced ΔLF (-21.84 ± 33.21% vs. -8.68 ± 34.59%, P = 0.01) and ΔHF (-17.26 ± 16.61% vs. -1.28 ± 9.81%, P = 0.01) than patients with recurrence. Multivariate regression analysis showed that both ΔLF (HR: 1.07, P = 0.04) and ΔHF (HR: 1.11, P = 0.01) were associated with AF recurrence. After adjusting for FTI, ΔLF was no longer associated with AF recurrence (HR: 1.05, P = 0.10). ΔHF remained associated with AF recurrence (HR: 1.08, P = 0.03), but the correlation coefficient was decreased (HR: 1.08, P = 0.03). CONCLUSION: Decreased autonomic nerve function is a valid predictor of AF recurrence and is indicated by the extent of ablation injury, which is independently associated with AF recurrence after CPVI.

Effects of febuxostat on atrial remodeling in a rabbit model of atrial fibrillation induced by rapid atrial pacing.

BACKGROUND: Febuxostat, a novel nonpurine selective inhibitor of xanthine oxidase (XO), may be used in the prevention and management of atrial fibrillation (AF). The purpose of this study was to evaluate the effects of febuxostat on atrial remodeling in a rabbit model of AF induced by rapid atrial pacing (RAP) and the mechanisms by which it acts. METHODS: Twenty-four rabbits were randomly divided into four groups: sham-operated group (Group S), RAP group (Group P), RAP with 5 mg/kg per day febuxostat group (Group LFP), and RAP with 10 mg/kg per day febuxostat group (Group HFP). All rabbits except those in Group S were subjected to RAP at 600 beats/min for four weeks. The effects of febuxostat on atrial electrical and structural remodeling, markers of inflammation and oxidative stress, and signaling pathways involved in the left atrium were examined. RESULTS: Shortened atrial effective refractory period (AERP), increased AF inducibility, decreased mRNA levels of Cav1.2 and Kv4.3, and left atrial enlargement and dysfunction were observed in Group P, and these changes were suppressed in the groups treated with febuxostat. Prominent atrial fibrosis was observed in Group P, as were increased levels of TGF-ß1, Collagen I, and α-SMA and decreased levels of Smad7 and eNOS. Treatment with febuxostat attenuated these differences. Changes in inflammatory and oxidative stress markers induced by RAP were consistent with the protective effects of febuxostat. CONCLUSIONS: This study is the first to find that febuxostat can inhibit atrial electrical and structural remodeling of AF by suppressing XO and inhibiting the TGF-ß1/Smad signaling pathway.

Diagnostic Performance of a Smart Device With Photoplethysmography Technology for Atrial Fibrillation Detection: Pilot Study (Pre-mAFA II Registry).

BACKGROUND: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. The asymptomatic nature and paroxysmal frequency of AF lead to suboptimal early detection. A novel technology, photoplethysmography (PPG), has been developed for AF screening. However, there has been limited validation of mobile phone and smart band apps with PPG compared to 12-lead electrocardiograms (ECG). OBJECTIVE: We investigated the feasibility and accuracy of a mobile phone and smart band for AF detection using pulse data measured by PPG. METHODS: A total of 112 consecutive inpatients were recruited from the Chinese PLA General Hospital from March 15 to April 1, 2018. Participants were simultaneously tested with mobile phones (HUAWEI Mate 9, HUAWEI Honor 7X), smart bands (HUAWEI Band 2), and 12-lead ECG for 3 minutes. RESULTS: In all, 108 patients (56 with normal sinus rhythm, 52 with persistent AF) were enrolled in the final analysis after excluding four patients with unclear cardiac rhythms. The corresponding sensitivity and specificity of the smart band PPG were 95.36% (95% CI 92.00%-97.40%) and 99.70% (95% CI 98.08%-99.98%), respectively. The positive predictive value of the smart band PPG was 99.63% (95% CI 97.61%-99.98%), the negative predictive value was 96.24% (95% CI 93.50%-97.90%), and the accuracy was 97.72% (95% CI 96.11%-98.70%). Moreover, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of mobile phones with PPG for AF detection were over 94%. There was no significant difference after further statistical analysis of the results from the different smart devices compared with the gold-standard ECG (P>.99). CONCLUSIONS: The algorithm based on mobile phones and smart bands with PPG demonstrated good performance in detecting AF and may represent a convenient tool for AF detection in at-risk individuals, allowing widespread screening of AF in the population. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR-OOC-17014138; http://www.chictr.org.cn/showproj.aspx?proj=24191 (Archived by WebCite at http://www.webcitation/76WXknvE6).

[The relationship between high-sensitivity C-reactive protein (hsCRP) levels and atrial fibrillation early recurrence after paroxysmal atrial fibrillation radiofrequency catheter ablation].

OBJECTIVE: To prospectively clarify the predictive value of high-sensitivity C-reactive protein (hsCRP) on the risk for recurrent atrial arrhythmia in paroxysmal atrial fibrillation (PAF) population who accepted radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). METHODS: There were 57 consecutive patients (53.32±9.98 years; 42 males) with drug-refractory PAF who underwent RFCA were included. Plasma levels of hsCRP and high-sensitivity cardiac troponin T (hs-cTnT) were measured on admission and first five days after RFCA. Twenty-five patients (43.86%) had early recurrence of atrial fibrillation (ERAF). RESULTS: Compared to patients without ERAF (no-AF-recurrence group), baseline hsCRP levels had no significant difference in patients with ERAF (AF recurrence group). There were no significant differences in the peak hsCRP and hs-cTnT levels between no-AF-recurrence group and AF recurrence group. However, change of hsCRP level was significantly correlated with change in hs-cTnT level in patients undergoing RFCA (r=0.268, P=0.044). CONCLUSIONS: Among those AF patients undergoing ablation, change of hsCRP level could be for the myocardial injury related to RFCA procedure, which may not be a risk factor to predict ERAF. The variety of hsCRP level may be related to the degree of myocardial injury induced by RFCA.

Assessing bleeding risk in 4824 Asian patients with atrial fibrillation: The Beijing PLA Hospital Atrial Fibrillation Project.

The risks of major bleeding and intracranial hemorrhage (ICH) are higher in Asian patients with atrial fibrillation (AF) compared to non-Asians. We aimed to investigate risk factors for bleeding, and validate the predictive value of available bleeding risk scores (mOBRI, HEMORR2HAGES, Shireman, HAS-BLED, ATRIA and ORBIT) in a large cohort of Chinese inpatients with AF. Using hospital electronic medical databases, we identified 4824 AF patients (mean age 67 years; 34.9% female) from January 1, 1995 to May 30, 2015, with median (interquartile) in-hospital days of 10 (7-16) days. On multivariate analysis, prior bleeds, vascular disease, anemia, prior stroke, and liver dysfunction were independent risk factors of major bleeding (all p < 0.05). C-statistics (95%CI) of the HAS-BLED score were 0.72 (0.65-0.79) for major bleeding events and 0.83 (0.75-0.91) for ICH (all p < 0.001). Compared to other risk scores, the HAS-BLED score was significantly better in predicting major bleeding events (Delong test, all P < 0.05, apart from mOBRI, HEMORR2HAGES) and ICH (all p < 0.05), and additionally, resulted in a net reclassification improvement (NRI) of 17.1-65.5% in predicting major bleeding events and 29.5-67.3% in predicting ICH (all p < 0.05). We conclude that the HAS-BLED score had the best predictive and discriminatory ability for major bleeding and ICH in an Asian/Chinese AF population.

Is dabigatran efficacy enough to prevent stroke in atrial fibrillation patient with high CHADS2 score during peri-procedural catheter radiofrequency ablation? A case report with literature review.

Atrial fibrillation (AF) is a major cause of thromboembolic (TE) events including stroke and transient ischemic attacks, catheter radiofrequency ablation (CA) has been demonstrated to effectively eliminate AF in majority of patients. During the peri-procedural CA of AF, dabigatran, a reversible direct thrombin inhibitor, has been proved as safe and efficacy as warfarin in the prevention of thromboembolic complication. However, for patients with CHADS2 score ≥3, sometimes dabigatran may not be an ideal substitute of warfarin. The current study presents delayed stroke occurred in a middle-aged AF patient with high CHADS2 score who had undergone successful CA of AF being on dabigatran, trans esophageal echocardiogram (TEE) detected a clot in the left atrium appendage (LAA) and magnetic resonance image (MRI) indicated stroke of left basal ganglia, therefore anticoagulant was switched to warfarin with well controlled international normalization ratio (INR) ranging from 2.0-3.0 and the patient eventually recovered without any TE events during the subsequent follow-up.

Renal denervation suppresses atrial fibrillation in a model of renal impairment.

BACKGROUND: A close association exists between renal impairment (RI) and atrial fibrillation (AF) occurrence. Increased activity of the sympathetic nervous system (SNS) may contribute to the development of AF associated with RI. Renal denervation (RDN) decreases central sympathetic activity. OBJECTIVE: The main objective of the study was to explore the effects of RDN on AF occurrence and its possible mechanisms in beagles with RI. METHODS: Unilateral RI was induced in beagles by embolization of small branches of the renal artery in the right kidney using gelatin sponge granules in Model (n = 6) and RDN group (n = 6). The Sham group (n = 6) underwent the same procedure, except for embolization. Then animals in RDN group underwent radiofrequency ablation of the renal sympathetic nerve. Cardiac electrophysiological parameters, blood pressure, left ventricular end-diastolic pressure, and AF inducibility were investigated. The activity of the SNS, renin-angiotensin-aldosterone system (RAAS), inflammation and atrial interstitial fibrosis were measured. RESULTS: Embolization of small branches of the renal artery in the right kidney led to ischemic RI. Heart rate, P wave duration and BP were increased by RI, which were prevented or attenuated by RDN. Atrial effective refractory period was shortened and AF inducibility was increased by RI, which were prevented by RDN. Antegrade Wenckebach point was shortened, atrial and ventricular rates during AF were increased by RI, which were attenuated or prevented by RDN. Levels of norepinephrine, renin and aldosterone in plasma, norepinephrine, angiotensin II, aldosterone, interleukin-6 and high sensitivity C-reactive protein in atrial tissue were elevated, and atrial interstitial fibrosis was enhanced by RI, which were attenuated by RDN. CONCLUSIONS: RDN significantly reduced AF inducibility, prevented the atrial electrophysiological changes in a model of RI by combined reduction of sympathetic drive and RAAS activity, and inhibition of inflammation activity and fibrotic pathway in atrial tissue.

Effects of body mass index on risks for ischemic stroke, thromboembolism, and mortality in Chinese atrial fibrillation patients: a single-center experience.

BACKGROUND: Obesity is considered to be related to recurrence of atrial fibrillation (AF), left atrial thrombus formation, and atrial remodeling. However, whether obesity is an independent risk factor for stroke and other thromboembolic events is still controversial. OBJECTIVE: This study aimed to investigate the effects of body mass index (BMI) on the risks of stroke, thromboembolism, and mortality in AF patients. METHODS: Patients who were diagnosed with nonvalvular AF were included in this observational, retrospective study. The study population was stratified by BMI at baseline. The Cox proportional hazard model was adopted to calculate adjusted hazard ratios of risk factors for adverse clinical events (stroke, thromboembolism, and mortality). RESULTS: A total of 1286 AF patients (males, 78.30%; mean age, 74.50 years; 94.48% paroxysmal AF) were followed up for a median of 2.1 years (IQR: 1.5-2.9 years). Overall, 159 patients died. A total of 84 strokes and 35 thromboembolic events occurred. Multivariate analysis showed that overweight (25.0≤BMI<30.0 kg/m2) and age ≥75 years were independent risk factors for ischemic stroke (both P<0.01). Obesity (BMI ≥30.0 kg/m2), age ≥75 years, persistent/permanent AF, and prior thromboembolism were independent risk factors for thromboembolism (all P<0.05). Underweight (BMI <18.5 kg/m2), age ≥75 years, prior ischemic stroke/transient ischemic attack, renal dysfunction, and heart failure were independent risk factors for all-cause deaths (all P<0.05). CONCLUSIONS: Overweight or obesity may be a risk factor of ischemic stroke and thromboembolism in AF patients. Excessive low weight is significantly associated with increased all-cause mortality.

Electrophysiological characteristics of paroxysmal atrial fibrillation originating from superior vena cava: a clinical analysis of 30 cases.

To analyze characteristics of electrocardiogram (ECG), electrophysiological intracardiac mapping and radiofrequency ablation (RF) of paroxysmal atrial fibrillation (PAF) originating from superior vena cava (SVC), aiming to investigate electrophysiological characteristics of PAF with SVC origin. Clinical data of 30 subjects (18 men and 12 women, aged, 58.6 ± 15.5 years) with PAF of SVC origin were retrospectively analyzed; All patients underwent RF during 2006.9-2012.7. ECG of AF and atrial premature contractions (APCs), procedure and fluoroscopic time, numbers of ablation sites within SVC, complications and success rate were studied. Compared with P wave of sinus rhythm (SR), APCs of SVC origin exhibited higher amplitude in lead II (0.23 ± 0.11 vs. 0.15 ± 0.06 mv), III (0.19 ± 0.09 vs. 0.13 ± 0.08 mv), AVF (0.21 ± 0.13 vs. 0.14 ± 0.10 mv), V2 (0.24 ± 0.07 vs. 0.15 ± 0.09 mv) and V3 (0.21 ± 0.09 vs. 0.12 ± 0.05 mv) (P < 0.05), as well as more biphasic polarity in lead V1 (80.0% vs. 26.6%, P < 0.05) and isoelectric in AVL (60.0% vs. 6.7%, P < 0.05). In terms of left pulmonary vein (LPV) and right pulmonary vein (RPV) electrical isolation, procedure time (14.3 ± 11.5 vs. 33.7 ± 14.2, 28.1 ± 6.8 min, P < 0.05), fluoroscopic time (9.6 ± 3.8 vs. 21.1 ± 9.3, 19.4 ± 9.7 min, P < 0.05), ablation sites (11.2 ± 3.1 vs. 37.1 ± 13.7, 31.4 ± 10.4 points, P < 0.05) of SVC isolation (SVCI) remarkably decreased compared with that of mean LPV and RPV. After the procedure, 9 patients still presented paroxymal rapid firing within the SVC in the setting of SR restoration, 2 patients developed paroxysmal atrial flutter within 1 month after completion of ablation and were controlled by antiarrhythmic drugs. The APCs and AF of SVC origin manifested distinctive ECG features, which could be helpful to distinguish SVC from other foci before ablation, the completion of SVCI required shorter procedure and fluoroscopic time, as well as less ablation points, and meanwhile, the success rate was high with less complication.

Role of inflammation in the initiation and maintenance of atrial fibrillation and the protective effect of atorvastatin in a goat model of aseptic pericarditis.

The present study was designed to determine the association between atrial fibrillation (AF) and inflammation in a goat sterile pericarditis model and to assess the effect of atorvastatin, a cholesterol­reducing drug, on AF. A total of 15 adult male goats were randomly divided into control, untreated pericarditis and atorvastatin­treated pericarditis groups. Pericarditis was induced via thoracotomy and atorvastatin was administered orally (60 mg/day) to the goats in the latter group for the duration of the study, commencing 1 week prior to surgery. The levels of high­sensitivity C­reactive protein (hs­CRP), interleukin(IL)­6 and tumor necrosis factor­α (TNF­α) were significantly elevated following surgery in the untreated pericarditis and atorvastatin groups compared with the control group (P<0.05). However, lower levels of hs­CRP, IL­6 and TNF­α were observed in the atorvastatin group compared with the untreated pericarditis group (P<0.05). Additionally, the animals in the atorvastatin­treated pericarditis group had a longer effective refractory period (ERP) and a higher rate adaptation of the ERP compared with those in the untreated pericarditis group (P<0.05). There was a significant negative correlation between the levels of ERP and hs­CRP in the untreated pericarditis group. The inducibility of AF in the left atrium and the duration of AF in the untreated pericarditis and atorvastatin­treated groups increased significantly following surgery (P<0.05). The pericarditis group, however, had a longer duration of AF compared with the atorvastatin group (P<0.05). Thus, inflammation may promote AF by shortening atrial ERP and by reducing the rate adaptation of ERP. These results suggested that atorvastatin can attenuate AF by inhibiting inflammation and may assist in preventing the occurrence and recurrence of AF following cardiac surgery.

Impact of body mass index on the development of pocket hematoma: A retrospective study in Chinese people.

BACKGROUND: Pocket hematoma is one of the major complications associated with cardiovascular implantable electronic devices (CIEDs) implantation. The aim of this study is to evaluate the impact of body mass index (BMI) on the occurrence of pocket hematoma after CIEDs implantation. METHODS: The study is a retrospective review of 972 patients receiving CIEDs implantation between 2008 and 2012 in a tertiary hospital. RESULTS: Twenty two patients (2.2%) developed severe pocket hematoma requiring re-intervention. The hematoma rate (4.6%, n = 15) of patients with a BMI of < 23 kg/m(2) was significantly higher compared with that of patients with a BMI of ≥ 23 kg/m(2) (1.1%, n = 7, P < 0.001). In multivariate regression analysis, a BMI < 23.0 kg/m(2) may be associated with the development of severe pocket hematoma. An increase of 1.0 kg/m(2) in BMI was associated with lower incidence of hematoma formation (OR: 0.84; 95% CI: 0.74-0.95; P = 0.006). CONCLUSION: BMI < 23 kg/m(2) was associated with a higher incidence of pocket hematoma, requiring re-intervention. The data support that great care must be taken when patients were with a lower BMI received CIEDs implantation.

Establishment of a model of renal impairment with mild renal insufficiency associated with atrial fibrillation in canines.

BACKGROUND: Chronic kidney disease and occurrence of atrial fibrillation (AF) are closely related. No studies have examined whether renal impairment (RI) without severe renal dysfunction is associated with the occurrence of AF. METHODS: Unilateral RI with mild renal insufficiency was induced in beagles by embolization of small branches of the renal artery in the left kidney for 2 weeks using gelatin sponge granules in the model group (n = 5). The sham group (n = 5) underwent the same procedure, except for embolization. Parameters associated with RI and renal function were tested, cardiac electrophysiological parameters, blood pressure, left ventricular pressure, and AF vulnerability were investigated. The activity of the sympathetic nervous system, renin-angiotensin-aldosterone system, inflammation, and oxidative stress were measured. Histological studies associated with atrial interstitial fibrosis were performed. RESULTS: Embolization of small branches of the renal artery in the left kidney led to ischemic RI with mild renal insufficiency. The following changes occurred after embolization. Heart rate and P wave duration were increased. Blood pressure and left ventricular systolic pressure were elevated. The atrial effective refractory period and antegrade Wenckebach point were shortened. Episodes and duration of AF, as well as atrial and ventricular rate during AF were increased in the model group. Plasma levels of norepinephrine, renin, and aldosterone were increased, angiotensin II and aldosterone levels in atrial tissue were elevated, and atrial interstitial fibrosis was enhanced after 2 weeks of embolization in the model group. CONCLUSIONS: We successfully established a model of RI with mild renal insufficiency in a large animal. We found that RI with mild renal insufficiency was associated with AF in this model.

Protective effects of apocynin on atrial electrical remodeling and oxidative stress in a rabbit rapid atrial pacing model.

It has been proposed that apocynin might be used in the prevention and management of atrial fibrillation (AF). The purpose of this study was to investigate the effects of apocynin on atrial electrical remodeling and oxidative stress promoted by rapid atrial pacing (RAP) in rabbits. New Zealand white rabbits were subjected to RAP with or without apocynin treatment. Serial electrophysiological studies (EPS) were performed at baseline and every half hour after RAP onset. Superoxide dismutase (SOD) and lactate dehydrogenase (LDH) activities and Ca²âº content in tissue homogenates of both atria were assayed after EPS. In the RAP group but not in the sham-operated and RAP with apocynin groups, atrial effective refractory periods (AERPs) at cycle length of 200 and 150 ms shortened most clearly by 20.8 ± 10.2 ms at 3 h (P < 0.001) and by 12.8 ± 11.1 ms at 2 h (P < 0.05) respectively, and AERP rate adaptation decreased to minus values. Higher AF inducibility (66.7%) and longer AF duration (an average of 37.8 min) were presented in the RAP group. Compared with the other groups, SOD activity was lower, and LDH activity and Ca²âº content were higher in the RAP group. Similar differences were not found between the sham-operated and the RAP with apocynin treatment groups. These data show that apocynin attenuates the development of atrial electrical remodeling in a short period of 3-hour RAP, and reduces RAP-mediated inducibility and duration of AF in this model.

Protective effect of piperine on electrophysiology abnormalities of left atrial myocytes induced by hydrogen peroxide in rabbits.

AIMS: Piperine had protective effects on oxidative stress damage of ventricular myocytes by hydrogen peroxide (H2O2). In this study we aimed to explore the protective effect of piperine on abnormalities of the cardiac action potential (AP) and several ion currents induced by hydrogen peroxide (H2O2) in single rabbit left atrial myocyte. MAIN METHODS: Conventional microelectrodes were used to record action potential duration (APD), resting membrane potential (RMP) and some ion currents (ICa,L,Ito,IK1 and Ikur,ect.), before and after H2O2 administration with or without piperine. KEY FINDINGS: The piperine (7 µmol/L) had no significant effect on APD, ICa,L,Ito,IK1 and Ikur and their channel dynamics. In the presence of 50 µmol/L H2O2, APD50 and APD90 shortened (P<0.01), amplitude of RMP decreased (P<0.05), the peak of ICa,L reduced significantly (P<0.05). Piperine (7 µmol/L) significantly alleviated the inhibiting effect of H2O2 on APD and ICa,L (P<0.01) and protected the changes of ICa,L dynamics induced by H2O2. The peak current of Ito was reduced significantly (P<0.05); Piperine (7 µmol/L) significantly alleviated the inhibiting effect of H2O2 on Ito (P<0.01). In addition, piperine protected the changes of Ito dynamics induced by H2O2. The peak current of IK1 and IKUr was significantly reduced (P<0.05); Piperine (7 µmol/L) alleviated the inhibiting effect of H2O2 on IK1 and IKUr significantly (P<0.01). In addition, piperine protected the changes of IKUr dynamics induced by H2O2. SIGNIFICANCE: These results suggest that piperine effectively protects atrial myocytes from oxidative stress injury in atrial electrophysiology.

[Ultrastructural study of the pulmonary veins in pigs].

OBJECTIVE: To explore the possible relationship between the ultrastructural characteristics of pulmonary veins and the pathogenesis of atrial fibrillation originating from pulmonary veins. METHODS: The pulmonary veins from domestic pigs were serially sectioned (2 mm) transversely along the vessels. The odd number sections were fixed in 10% phosphate buffered formalin solution and the even number sections were fixed in 3% Glutaral for further electron microscopy observations. RESULTS: Two cell types were found in the pulmonary veins of pigs. One cell type was the P-like cells that had an empty-appearing cytoplasm containing only sparse myofibrils and small mitochondria, both of which were randomly distributed. Another cell type was slender transitional cells with plenty of longitudinally displayed myofibrils. CONCLUSION: P-like cells in the pig pulmonary veins were found using electron microscopy in this study and ectopic beats from P-like cells in the myocardial sleeves in the pulmonary veins might be responsible for atrial fibrillation originating from pulmonary veins.

[Effects of atrial excitable period on the stability of atrial fibrillation in goats].

OBJECTIVE: To investigate the effects of atrial excitable period (EP) on the stability of atrial fibrillation (AF) in goats. METHODS: Ten female goats were instrumented with epicardial electrodes patches on the left atrium (LA) free wall. AF was induced and maintained by a home-made stimulator with frequency of 50 Hz at a 1-second duration and a 2-seconds interval. The stimulator was disconnected regularly. AF-induced duration, average AF cycle length (AFCL), and atrial effective refractory period during AF (ERP(AF)) were measured; EP was calculated by AFCL-ERP(AF). RESULTS: Eight goats were studied. Persistent AF (> 24 h) could be induced in all the 8 goats within 6-16 days. When the induced AF lasted for 3-10 min or 24 h, the AFCL was 98.3 ms +/- 11.0 ms and 84.9 ms +/- 5.2 ms (P < 0.05), respectively, ERP(AF) was 90.5 ms +/- 13.2 ms and 63.0 ms +/- 4.8 ms (P < 0.05), respectively, and EP was 7.8 ms +/- 2.4 ms and 21.9 ms +/- 3.5 ms (P < 0.05), respectively. CONCLUSION: The decrease in ERP(AF) is more significant than the shortening in AFCL, resulting in the gradually widening of EP which may contribute to the perpetuation of AF.