Shaowen Liu

Procedural Arrhythmia Termination and Long-Term Single-Procedure Clinical Outcome in Patients with Non-paroxysmal Atrial Fibrillation

The influence of procedural arrhythmia termination on long‐term single‐procedure clinical outcome in patients with non‐paroxysmal atrial fibrillation (AF) remains controversial.

Nav1.8 channels in ganglionated plexi modulate atrial fibrillation inducibility

AIMS Emerging evidences indicate that SCN10A/NaV1.8 is associated with cardiac conduction and atrial fibrillation, but the exact role of NaV1.8 in cardiac electrophysiology remains poorly understood. The present study was designed to investigate the effects of blocking NaV1.8 channels in cardiac ganglionated plexi (GP) on modulating cardiac conduction and atrial fibrillation inducibility in the canine model. METHODS AND RESULTS Thirteen mongrel dogs were randomly enrolled. Right cervical vagus nerve stimulation (VNS) was applied to determine its effects on the sinus rate, ventricular rate during atrial fibrillation, PR interval, atrial effective refractory period, and the cumulative window of vulnerability. The NaV1.8 blocker A-803467 (1 μmol/0.5 mL per GP, n = 7) or 5% DMSO/95% polyethylene glycol (0.5 mL per GP, n = 6, control) was injected into the anterior right GP and the inferior right GP. The effects of VNS on the sinus rate, ventricular rate, PR interval, atrial effective refractory period, and the cumulative window of vulnerability were significantly eliminated at 10, 35, and 90 min after A-803467 injection. In separate experiments (n = 8), A-803467 blunted the slowing of sinus rate with increasing stimulation voltage of the anterior right GP at 10 min after local injection. CONCLUSIONS Blockade of NaV1.8 channels suppresses the effects of VNS on cardiac conduction and atrial fibrillation inducibility, most likely by inhibiting the neural activity of the cardiac GP.

Local ischemic postconditioning during primary percutaneous coronary intervention: a meta-analysis.

Objectives: To investigate current evidence linking ischemic postconditioning (IPC) to cardioprotection in patients receiving primary percutaneous coronary intervention (PCI). Methods: We performed searches of PubMed, Embase, MEDLINE and Cochrane databases from January 1998 to May 2011 for identifying relevant studies comparing IPC with usual care in patients undergoing primary PCI. A meta-analysis of eligible studies was assessed by Review Manager 5.0. Results: Thirteen studies were eligible. Compared to the control, observed outcomes such as peak creatine kinase [weighted mean difference (WMD) –537.48, 95% confidence interval (CI) –779.32 to –295.65 IU/l], peak creatine kinase-myocardial band (WMD –61.11, 95% CI –76.56 to –45.66 U/l), complete ST-segment resolution (risk ratio 1.38, 95% CI 1.07 to 1.77), blush grade during reflow (WMD 0.64, 95% CI 0.49 to 0.78), corrected TIMI frame count, single-photon emission computed tomography determining infarct size, long-term left ventricular ejection fraction and short-term and long-term wall motion score indexes were improved in IPC group, with less occurrence of heart failure during the 3-month to 3.4-year follow-up. Conclusions: Though current evidence indicates that IPC provides potential cardioprotection to patients receiving primary PCI, larger adequately powered studies should be undertaken to confirm its advantages.

Lysophosphatidic Acid Increases the Electrophysiological Instability of Adult Rabbit Ventricular Myocardium by Augmenting L-Type Calcium Current

Lysophosphatidic acid (LPA) has diverse actions on the cardiovascular system and is widely reported to modulate multiple ion currents in some cell types. However, little is known about its electrophysiological effects on cardiac myocytes. This study investigated whether LPA has electrophysiological effects on isolated rabbit myocardial preparations. The results indicate that LPA prolongs action potential duration at 90% repolarization (APD90) in a concentration- and frequency-dependent manner in isolated rabbit ventricular myocytes. The application of extracellular LPA significantly increases the coefficient of APD90 variability. LPA increased L-type calcium current (ICa,L) density without altering its activation or deactivation properties. In contrast, LPA has no effect on two other ventricular repolarizing currents, the transient outward potassium current (Ito) and the delayed rectifier potassium current (IK). In arterially perfused rabbit left ventricular wedge preparations, the monophasic action potential duration, QT interval, and Tpeak-end are prolonged by LPA. LPA treatment also significantly increases the incidence of ventricular tachycardia induced by S1S2 stimulation. Notably, the effects of LPA on action potentials and ICa,L are PTX-sensitive, suggesting LPA action requires a Gi-type G protein. In conclusion, LPA prolongs APD and increases electrophysiological instability in isolated rabbit myocardial preparations by increasing ICa,L in a Gi protein-dependent manner.

Common variants predict recurrence after nonfamilial atrial fibrillation ablation in Chinese Han population

BACKGROUND Genome-wide association studies (GWAS) have identified several loci associated with atrial fibrillation (AF) and have been reportedly associated with response to catheter ablation for AF in patients of European ancestry; however, associations between susceptibility loci and clinical recurrence of AF after catheter ablation have not been examined in Chinese Han populations. To the personalization of catheter ablation for AF, we examined whether these single nucleotide polymorphisms (SNPs) can predict clinical outcomes after catheter ablation for AF in Chinese Han population. METHODS AND RESULTS The association between 8 SNPs and AF was studied in 1418 AF patients and 1424 controls by the unconditional logistic regression analysis. The survival analyses were used to compare AT/AF recurrence differences among 438 AF patients, which were classified by the genotype of rs2200733. rs2200733 and rs6590357 were significantly associated with AF in Chinese Han population. In addition, rs2200733 was associated with clinical recurrence of AF after catheter ablation. In Kaplan-Meier survival analysis, the recurrence-free rates for AF with TT and with TC+CC were 35.5% and 61.9%, respectively (P=0.0009). In multivariate Cox regression analysis, rs2200733 was strong independent risk factor for recurrence. CONCLUSION rs2200733 risk allele at the 4q25 predicted impaired clinical response to catheter ablation for AF in Chinese Han population. Our findings suggested rs2200733 polymorphism may be used as a clinical tool for selection of patients for AF catheter ablation.

Polymorphisms of Renin-Angiotensin-Aldosterone System Gene in Chinese Han Patients with Nonfamilial Atrial Fibrillation

Background Atrial fibrillation(AF) is the most common arrhythmia in the adult population. The activated renin-angiotensin-aldosterone system (RAS) has been reported to play an important role in the pathogenesis of atrial fibrillation. The aim of this study was to investigate the association between nonfamilial AF and polymorphisms in RAS gene. Methods A total of 931 patients with nonfamilial AF, 663 non-AF heart disease patients and 727 healthy subjects were selected. 10 tagSNPs (tSNPs) (ACE gene rs8066114, AGT gene rs7539020, rs3789678, rs2478544, rs11568023, rs2478523, rs4762, rs699 and CYP11B2 rs3802230, rs3097) were chosen and genotyped in our study. Single-locus analysis and haplotype analysis were used in this study. Results In single-locus analysis, we found rs11568023 and rs3789678 in AGT gene were associated with nonfamilial AF in Chinese Han population. AF risk was associated with rs3789678 between the AF group and control groups. Under dominant model, the significant AF risk was observed in rs3789678 between the AF group and non AF heart control group; And the protective effect was found in rs11568023, compared with the non-AF heart disease control group. In multilocus haplotype analysis, the association between frequencies of the haplotypes and AF risk was showed in AGT gene (rs7539020-rs3789678), compared ‘TT’ haplotype with the common ‘TC’ haplotype, adjusted for age, gender, LVEF, LVEDD, LAD and frequency of hypertension and diabetes. The diplotype with ‘TC’, carrying rs3789678-C-allele, was associated with reduced risk of AF between the AF group and the healthy control group. The diplotype with ‘TT’ haplotype in the same block, carrying rs3789678-T-allele, was associated with increased risk of AF. Conclusions Via a large-scale case-control study, we found that rs3789678 site was potential susceptible locus of AF whereas rs11568023 was protective factor.

A dual-loop bi-atrial macro-reentry flutter during atrial fibrillation ablation.

Dual-loop macro-reentry atrial flutter (AFL) is an atypical AFL, which has two loops of the reentry circuit usually localized within single atrium. In this case report, we present a double-loop bi-atrial flutter during atrial fibrillation ablation, in which the two reentry circuit loops were located around the inferior vena cava (IVC) and the mitral annulus, (MA) respectively.

Renal Denervation Suppresses the Inducibility of Atrial Fibrillation in a Rabbit Model for Atrial Fibrosis.

Renal denervation (RD) was reported to reduce the susceptibility of atrial fibrillation (AF), but the underlying mechanism has not been well understood. This study was performed to investigate the effect of RD on the inducibility of AF in a rabbit model for atrial fibrosis and to explore the potential mechanisms. Thirty-five rabbits were randomly assigned into sham-operated group (n = 12), abdominal aortic constriction (AAC) group (n = 12) and AAC with RD (AAC-RD) group (n = 11). The incidence of AF induced by burst pacing in atriums was determined. Blood was collected to measure the levels of rennin, angiotensin II and aldosterone. Atrial samples were preserved to evaluate protein and gene expression of collagen, connective tissue growth factor (CTGF) and transforming growth factor-β1 (TGF-β1). Our data suggested cardiac structure remodeling and atrial fibrosis were successfully induced by AAC. Compared with the AAC group, the AAC-RD rabbits had smaller ascending aortic diameter and left ventricular end-systolic diameter. For burst pacing at the left atrium (LA), AF was induced in two of the 12 rabbits in the sham-operated group, 10 of the 12 rabbits in the AAC group, and 2 of the 11 rabbits in the AAC-RD group, with great difference among the three groups (P = 0.001). The percentage of LA burst stimulations with induced AF achieved 47.2% in the AAC group, which was higher than those in both the AAC-RD (12.1%) and the Sham-operated (5.6%) groups. Significantly increasing intercellular space in the AAC group (P<0.001) compared with the sham-operated rabbits. RD clearly decreased the volume fraction of collagen in LA and right atrium compared with that of the AAC group (P< 0.01). AAC-induced elevation of collagen I, CTGF and TGF-β1 was suppressed by RD. In conclusion, RD suppressed the inducibility of AF in a rabbit model for pressure associated atrial fibrosis, potentially by modulating renin-angiotensin-aldosterone system and decreasing pro-fibrotic factors.

Multiple Manifested Accessory Atrioventricular Pathways in a Patient without Obvious Structural Heart Disease

A 53-year-old man was referred for treatment of preexcitation syndrome, which was first diagnosed after having had cardioversion for presyncope due to atrial fibrillation. He had hypertension controlled with losantan. The ECG indicated multiple accessory pathways (APs), located on the tricuspid annulus (TVA). Echocardiography revealed a dilated left atrium and slight left ventricular hypertrophy (associated with hypertension) without Ebstein anomaly. The procedure was performed with a three-dimensional (3-D) mapping system (CARTO 3). Manifested APs were mapped

Clinical implications of and factors influencing dissociated pulmonary vein potentials

BACKGROUND Factors influencing dissociated pulmonary vein (PV) potentials (DPVPs) in atrial fibrillation (AF) patients undergoing circumferential PV isolation have not been investigated. Furthermore, the clinical implications of such DPVPs remain controversial. METHODS Circumferential PV isolation as a first ablation procedure was performed in 688 consecutive patients with AF (460 men; mean age, 58.9±10.5 years). The clinical implications of and factors influencing DPVPs were evaluated. RESULTS Acute PV isolation was achieved in 679 (98.7%) patients. A total of 578 (42.6%) ipsilateral PVs with DPVPs were documented in 378 (55.7%) patients (DPVPs group). Multivariate analysis revealed that male gender [odds ratio (OR): 1.894; 95% confidence interval (CI): 1.344-2.667; p<0.001] and paroxysmal AF (OR: 1.715; 95% CI: 1.182-2.488; p=0.005) were independent factors for DPVPs. The incidence of acute and intraoperative PV reconnection (PVR) was higher in the DPVPs group than in the non-DPVPs group (33.1% vs. 17.9%; p<0.001 and 44.4% vs. 28.2%; p<0.001). After the first procedure, 244 (65.6%) DPVPs-group patients and 168 (56.4%; p=0.015) non-DPVPs group patients were free from AF recurrence. During repeat procedures, PVR incidence was similar in the DPVPs group (81.8%) and non-DPVPs groups (83.3%; p=0.863). CONCLUSION Male gender and paroxysmal AF were independent risk factors for DPVPs in patients undergoing circumferential PV isolation. DPVPs had a significant impact on acute and intraoperative PVR. The outcomes of the first ablation procedure were better in patients with DPVPs.