Percutaneous left atrial appendage closure with SeaLA device in non-valvular atrial fibrillation.

OBJECTIVES: The clinical efficacy and safety of a novel left atrial appendage (LAA) occluder of the SeaLA closure system in patients with nonvalvular atrial fibrillation (NVAF) were reported. BACKGROUND: Patients with NVAF are at a higher risk of stroke compared to healthy individuals. Left atrial appendage closure (LAAC) has emerged as a prominent strategy for reducing the risk of thrombosis in individuals with NVAF. METHODS: A prospective, multicenter study was conducted in NVAF patients with a high risk of stroke. RESULTS: The LAAC was successfully performed in 163 patients. The mean age was 66.93 ± 7.92 years, with a mean preoperative CHA2DS2-VASc score of 4.17 ± 1.48. One patient with residual flow >3 mm was observed at the 6-month follow-up, confirmed by TEE. During the follow-up, 2 severe pericardiac effusions were noted, and 2 ischemic strokes were observed. Four device-related thromboses were resolved after anticoagulation treatment. There was no device embolism. CONCLUSIONS: The LAAC with the SeaLA device demonstrates encouraging feasibility, safety, and efficacy outcomes.

Percutaneous Left Atrial Appendage Closure With a Novel LAA Occluder for Stroke Prevention in Atrial Fibrillation.

Background: More than 90% of thromboses originate from the left atrial appendage (LAA) in patients with nonvalvular atrial fibrillation (NVAF). Objectives: This study was designed to investigate the safety and efficacy of LAA closure with the Leftear device (Pulse Scientific) in NVAF patients. Methods: A prospective, multicenter, registry-based study was conducted in 200 NVAF patients with CHA2DS2-VASc (congestive heart failure, hypertension, age, diabetes, previous stroke/transient ischemic attack, vascular disease, female sex) scores ≥2. The primary safety endpoint was defined as any serious adverse events. Efficacy was assessed by a primary composite endpoint of hemorrhagic or ischemic stroke, systemic embolism, and cardiac or unexplained death at 1 year of follow-up. Results: The device was implanted in 196 patients, with 1-stop LAA closure combined with atrial fibrillation ablation implemented in 133 patients. The immediate success rate was 100%. There were serious adverse events in 9 patients (4.5%; 95% CI: 1.6%-7.4%), which mainly occurred in 1-stop LAA closure. All pericardial tamponades occurred in 6 patients with 1-stop LAA closure. No patient experienced a major bleeding event or acute device-related thrombus. During the 12-month follow-up period, the risk of the primary composite endpoint was 1.6% (95% CI: 0.3%-4.5%), and statistical noninferiority was achieved (the upper bound of 95% CI: 4.5% < the prespecified maximum annual incidence of 8.0%). Ischemic stroke occurred in 1 patient, 3 patients had incomplete LAA sealing, and no delayed device-related thrombus was found. Conclusions: LAA closure with the novel disc-like occluder shows high procedural success, satisfactory safety, and encouraging efficacy for stroke prevention in patients with NVAF. Compared with 1-stop LAA closure, single LAA closure may be more tolerable. (A multicenter, single-arm clinical trial to evaluate the efficacy and safety of left atrial appendage system for left atrial appendage occlusion in patients with non-valvular atrial fibrillation; ChiCTR1900023035).

Small extracellular vesicles containing miR-486-5p promote angiogenesis after myocardial infarction in mice and nonhuman primates.

Stem cell-derived small extracellular vesicles (sEVs) promote angiogenesis after myocardial infarction (MI). However, the components of sEVs that contribute to these effects and the safety and efficiency of engineered sEV treatment for MI remain unresolved. Here, we observed improved cardiac function, enhanced vascular density, and smaller infarct size in mice treated with the sEVs from hypoxia-preconditioned (HP) mesenchymal stem cells (MSCs) (HP-sEVs) than in mice treated with normoxia-preconditioned (N) MSCs (N-sEVs). MicroRNA profiling revealed a higher abundance of miR-486-5p in HP-sEVs than in N-sEVs, and miR-486-5p inactivation abolished the benefit of HP-sEV treatment, whereas miR-486-5p up-regulation enhanced the benefit of N-sEV treatment. Matrix metalloproteinase 19 (MMP19) abundance was lower in HP-sEV-treated than N-sEV-treated mouse hearts but was enriched in cardiac fibroblasts (CFs), and Mmp19 was identified as one of the target genes of miR-486-5p. Conditioned medium from CFs that overexpressed miR-486-5p or silenced MMP19 increased the angiogenic activity of endothelial cells; however, medium from CFs that simultaneously overexpressed Mmp19 and miR-486-5p abolished this effect. Mmp19 silencing in CFs reduced the cleavage of extracellular vascular endothelial growth factor (VEGF). Furthermore, miR-486-5p-overexpressing N-sEV treatment promoted angiogenesis and cardiac recovery without increasing arrhythmia complications in a nonhuman primate (NHP) MI model. Collectively, this study highlights the key role of sEV miR-486-5p in promoting cardiac angiogenesis via fibroblastic MMP19-VEGFA cleavage signaling. Delivery of miR-486-5p-engineered sEVs safely enhanced angiogenesis and cardiac function in an NHP MI model and may promote cardiac repair.

Acetylcholine-Atropine Interactions: Paradoxical Effects on Atrial Fibrillation Inducibility.

Atropine (ATr) is well known as a cholinergic antagonist, however, at low concentrations ATr could paradoxically accentuate the parasympathetic actions of acetylcholine (ACh). In 22 pentobarbital anesthetized dogs, via a left and right thoracotomy, a leak-proof barrier was attached to isolate the atrial appendages (AAs) from the rest of the atria. In group 1 (Ach+ATr+Ach), ACh, 100 mM, was placed on the AA followed by the application of ATr, 2 mg/mL. The average atrial fibrillation (AF) duration was 17 ± 7 minutes. After ATr was applied to the AA and ACh again tested, the AF duration was markedly attenuated (2 ± 2 minutes, P < 0.05). In group 2 (ATr+Ach), ATr was initially applied to the AA followed by the application of ACh, 100 mM. There was no significant difference in AF duration (16 ± 4 minutes vs. 18 ± 2 minutes, P = NS). The inhibitory effect of ATr on induced HR reduction (electrical stimulation of the anterior right ganglionated plexi and vagal nerves) was similar between groups 1 and 2. These observations suggest that when ATr is initially administered it attaches to the allosteric site of the muscarinic ACh receptor (M2) leaving the orthosteric site free to be occupied by ACh. The M3 receptor that controls HR slowing does not show the same allosteric properties.

A Large-Scale Investigation of Hypoxia-Preconditioned Allogeneic Mesenchymal Stem Cells for Myocardial Repair in Nonhuman Primates: Paracrine Activity Without Remuscularization.

RATIONALE: The effectiveness of transplanted bone marrow mesenchymal stem cells (MSCs) for cardiac repair has been limited; thus, strategies for optimizing stem-cell-based myocardial therapy are needed. OBJECTIVE: The present study was designed to test our central hypothesis that hypoxia-preconditioned MSCs (HP-MSCs) are more effective than MSCs cultured under ambient oxygen levels for the treatment of myocardial injury in a large-scale (N=49), long-term (9 months), nonhuman primate (Cynomolgous monkeys) investigation. METHODS AND RESULTS: MSCs were engineered to express green fluorescent protein, cultured under ambient oxygen or 0.5% oxygen (HP-MSCs) for 24 hours and then tested in the infarcted hearts of Cynomolgus monkeys (1×10(7) cells per heart). Hypoxia preconditioning increased the expression of several prosurvival/proangiogenic factors in cultured MSCs, and measurements of infarct size and left-ventricular function at day 90 after myocardial infarction were significantly more improved in monkeys treated with HP-MSCs than in monkeys treated with the control vehicle; functional improvements in normal cultured bone marrow mesenchymal stem cells-treated monkeys were not significant. HP-MSCs transplantation was also associated with increases in cardiomyocyte proliferation, vascular density, myocardial glucose uptake, and engraftment of the transplanted cells and with declines in endogenous cell apoptosis, but did not increase the occurrence of arrhythmogenic complications. CONCLUSIONS: Hypoxia preconditioning improved the effectiveness of MSCs transplantation for the treatment of myocardial infarction in nonhuman primates without increasing the occurrence of arrhythmogenic complications, which suggests that future clinical trials of HP-MSCs transplantation are warranted.

Evaluation of the safety and efficacy of transcatheter aortic valve implantation in patients with a severe stenotic bicuspid aortic valve in a Chinese population.

OBJECTIVE: The purpose of this study is to evaluate the safety and efficacy of transcatheter aortic valve implantation (TAVI) in patients with a severe stenotic bicuspid aortic valve (BAV) in a Chinese population. While several groups have reported the feasibility, efficacy, and safety of TAVI for patients with a BAV, worldwide experience of the technique is still limited, especially in China. METHODS: From March 2013 to November 2014, high surgical risk or inoperable patients with symptomatic severe aortic stenosis (AS) who had undergone TAVI at our institution were selected for inclusion in our study. RESULTS were compared between a BAV group and a tricuspid aortic valve (TAV) group. RESULTS: Forty patients were included in this study, 15 (37.5%) of whom were identified as having a BAV. In the BAV group, the aortic valve area was smaller ((0.47±0.13) vs. (0.59±0.14) cm(2)), the ascending aortic diameter was larger ((40.4±4.4) vs. (36.4±4.3) mm), and the concomitant aortic regurgitation was lower. No significant differences were found between the groups in the other baseline characteristics. No differences were observed either in the choice of access or valve size. The procedural success achieved in this study was 100%. There were no differences between groups in device success (86.7% vs. 88.0%), 30-d mortality (6.7% vs. 8.0%), or 30-d combined end point (13.3% vs. 12.0%). The incidences of new pacemaker implantation, paravalvular regurgitation and other complications, recovery of left ventricle ejection fraction and heart function were similar in both groups. CONCLUSIONS: Patients with a severely stenotic BAV can be treated with TAVI, and their condition after treatment should be similar to that of people with a TAV.

Dysregulated expression of microRNAs and mRNAs in myocardial infarction.

Acute myocardial infarction (AMI) is a major cause of mortality in the general population. However, the molecular phenotypes and therapeutic targets of AMI patients remain unclear. By profiling genome-wide transcripts and microRNAs (miRNAs) in a cohort of 23 AMI patients and 23 non-AMI patients, we found 218 dysregulated genes identified in the infarcted heart tissues from AMI patients relative to non-AMI controls. Pathway enrichment analysis of the dysregulated genes pointed to cell signaling/communication, cell/organism defense and cell structure/motility. We next compared the expression profiles of potential regulating miRNAs, suggesting that dysregulation of a number of AMI-associated genes (e.g., IL12A, KIF1A, HIF1α and CDK13) may be attributed to the dysregulation of their respective regulating miRNAs. One potentially pathogenic miRNA-mRNA pair, miR-210-HIF1α, was confirmed in a mouse model of myocardial infarction (MI). Inhibition of miR-210 expression improved the survival and cardiac function of MI mice. In conclusion, we presented the pathologic relationships between miRNAs and their gene targets in AMI. Such deregulated microRNAs and mRNAs like miR-210 serve as novel therapeutic targets of AMI.

Experimental model of focal atrial tachycardia: clinical correlates.

BACKGROUND: The mechanisms underlying focal atrial tachycardia (AT) are unclear. METHODS: In 14 pentobarbital anesthetized dogs, a right thoracotomy allowed electrical stimulation (ES) of the anterior right ganglionated plexi (ARGP). After ES was applied to the ARGP at baseline, atropine, 1 mg/cc, was injected into the ARGP and repeat stimulation applied. After a left thoracotomy (n = 8), a similar procedure was followed by atropine injected into the superior left (SL) GP. RESULTS: ES (0.6-3.2 V) applied to the ARGP and SLGP caused an average reduction in sinus rate from 151 ± 14/min to 60 ± 11/min. At ≥4.5 V atrial fibrillation (AF) was induced (duration 48 ± 14 seconds). After injection of atropine into the ARGP or SLGP, ES applied to these GP induced no slowing of the sinus rate. Runs of AT were induced at an average voltage of 10 ± 2 V in 14 experiments (duration ≥4 minutes). AT was localized by ice mapping or by 3D noncontact mapping to the crista terminalis (n = 6), AV junction (n = 2) or a focal site at the left superior pulmonary vein (6). In AT lasting <4 minutes (n = 2), epinephrine injected into the GP significantly increased the AT duration. In 4/4 experiments, sustained AT could be terminated by intravenous esmolol. CONCLUSIONS: Atropine injected into the ARGP or SLGP promotes ES-induced AT whose duration is increased by adrenergic agonists and terminated by beta blockade. Presumably cholinergic blockade and accentuated release of adrenergic neurotransmitters provide the AT mechanism. The induced AT was found to be localized at sites similar to those reported clinically.

Inducibility of atrial fibrillation after GP ablations and "autonomic blockade": evidence for the pathophysiological role of the nonadrenergic and noncholinergic neurotransmitters.

BACKGROUND: Recent clinical reports that used cholinergic and adrenergic blockade (CAB) as an alternative to ganglionated plexi (GP) ablation to terminate atrial fibrillation (AF) showed mixed results. We investigated the role of other neurotransmitters in AF inducibility. METHODS: In 23 pentobarbital anesthetized dogs, a left and right thoracotomy allowed the attachment of electrode catheters to the left and right pulmonary veins and atrial appendages (AA). Programmed stimulation was used to determine the effective refractory periods (ERP) and AF inducibility, measured by the window of vulnerability (WOV). AF duration in response to acetylcholine (Ach; 100 mM) applied to the AA was measured before and after GP ablation + CAB and with vagus nerve stimulation (VNS). After GP ablation + CAB, Ach induced AF duration was determined in response to vasoactive intestinal peptide (VIP) and its specific antagonist ([Ac-Tyr1,D-phe2]-VIP). RESULTS: GP ablation + CAB significantly prolonged ERP, eliminated WOV, and suppressed the duration of Ach induced AF (P ≤ 0.01 for all). Also slowing of the heart rate by VNS was essentially blocked; however, with Ach 100 mM applied to the AA, VNS, and VIP applied to the AA markedly prolonged AF duration. This effect was blocked by the VIP antagonist. CONCLUSIONS: Neither GP ablation nor CAB can fully suppress AF inducibility arising from the atrial neural network. Our findings suggest that other neurotransmitters, such as VIP released during VNS, can promote sustained AF despite GP ablation and "autonomic blockade," which may further define the substrate for AF outside the pulmonary vein-atrial junctions.

Inhibition of atrial fibrillation by low-level vagus nerve stimulation: the role of the nitric oxide signaling pathway.

PURPOSE: We examined the role of the phosphatidylinositol-3 kinase (PI3K)/nitric oxide (NO) signaling pathway in low-level vagus nerve stimulation (LLVNS)-mediated inhibition of atrial fibrillation (AF). METHODS: In 17 pentobarbital anesthetized dogs, bilateral thoracotomies allowed the attachment of electrode catheters to the superior and inferior pulmonary veins and atrial appendages. Rapid atrial pacing (RAP) was maintained for 6 h. Each hour, programmed stimulation was used to determine the window of vulnerability (WOV), a measure of AF inducibility, at all sites. During the last 3 h, RAP was overlapped with right LLVNS (50 % below that which slows the sinus rate). In group 1 (n = 7), LLVNS was the only intervention, whereas in groups 2 (n = 6) and 3 (n = 4), the NO synthase inhibitor N (G)-nitro-L-arginine methyl ester (L-NAME) and the PI3K inhibitor wortmannin, respectively, were injected in the right-sided ganglionated plexi (GP) during the last 3 h. The duration of acetylcholine-induced AF was determined at baseline and at 6 h. Voltage-sinus rate curves were constructed to assess GP function. RESULTS: LLVNS significantly decreased the acetylcholine-induced AF duration by 8.2 ± 0.9 min (p < 0.0001). Both L-NAME and wortmannin abrogated this effect. The cumulative WOV (the sum of the individual WOVs) decreased toward baseline with LLVNS (p < 0.0001). L-NAME and wortmannin blunted this effect during the fifth (L-NAME only, p < 0.05) and the sixth hour (L-NAME and wortmannin, p < 0.05). LLVNS suppressed the ability of GP stimulation to slow the sinus rate, whereas L-NAME and wortmannin abolished this effect. CONCLUSION: The anti-arrhythmic effects of LLVNS involve the PI3K/NO signaling pathway.

Low-level transcutaneous electrical stimulation of the auricular branch of the vagus nerve: a noninvasive approach to treat the initial phase of atrial fibrillation.

BACKGROUND: We studied the effects of transcutaneous electrical stimulation at the tragus, the anterior protuberance of the outer ear, for inhibiting atrial fibrillation (AF). OBJECTIVE: To develop a noninvasive transcutaneous approach to deliver low-level vagal nerve stimulation to the tragus in order to treat cardiac arrhythmias such as AF. METHODS: In 16 pentobarbital anesthetized dogs, multielectrode catheters were attached to pulmonary veins and atria. Three tungsten-coated microelectrodes were inserted into the anterior right ganglionated plexi to record neural activity. Tragus stimulation (20 Hz) in the right ear was accomplished by attaching 2 alligator clips onto the tragus. The voltage slowing the sinus rate or atrioventricular conduction was used as the threshold for setting the low-level tragus stimulation (LL-TS) at 80% below the threshold. At baseline, programmed stimulation determined the effective refractory period (ERP) and the window of vulnerability (WOV), a measure of AF inducibility. For hours 1-3, rapid atrial pacing (RAP) was applied alone, followed by concomitant RAP+LL-TS for hours 4-6 (N = 6). The same parameters were measured during sinus rhythm when RAP stopped after each hour. In 4 other animals, bivagal transection was performed before LL-TS. RESULTS: During hours 1-3 of RAP, there was a progressive and significant decrease in ERP, increase in WOV, and increase in neural activity vs baseline (all P < .05). With RAP+LL-TS during hours 4-6, there was a linear return of ERP, WOV, and neural activity toward baseline levels (all P < .05, compared to the third-hour values). In 4 dogs, bivagal transection prevented the reversal of ERP and WOV despite 3 hours of RAP+LL-TS. CONCLUSIONS: LL-TS can reverse RAP-induced atrial remodeling and inhibit AF inducibility, suggesting a potential noninvasive treatment of AF.

The atrial neural network as a substrate for atrial fibrillation.

BACKGROUND: Previously, we showed that the ganglionated plexi (GP) on the atrium can play a critical role in the initiation and maintenance of atrial fibrillation (AF). We tested the role of the atrial neural network as a substrate for AF without the influence of the GP. METHODS: In pentobarbital-anesthetized open-chest dogs, two barriers across the left/right atrial appendage (AA) divided the AA into smaller and larger areas of approximately similar size, 2 cm². Electrical stimulation of the superior left and right GP allowed measurement of the greatest percent slowing of the heart rate prior to atrial excitation (n = 7). Acetylcholine (Ach; 1, 10, and 100 mM) was applied to the smaller and then to the larger area. In 22 dogs, the effects on AF duration in response to Ach applied to the atria were tested after GP ablations and atropine applied to the atria. RESULTS: GP function was unchanged by various concentrations of Ach applied to the smaller or larger areas of the atria. However, AF duration was significantly longer for each Ach concentration when applied to the larger versus the smaller area (p ≤ 0.01). AF was attenuated by GP ablations and atropine, but the differences between small and large areas were maintained. CONCLUSION: Ach on a larger area of the atria significantly increased the induced AF duration compared to an area half the size without changes in GP function suggesting that recruiting a larger area of the atrial neural network provided more of an AF substrate.

Antiarrhythmic effects of vasostatin-1 in a canine model of atrial fibrillation.

BACKGROUND: We examined the antiarrhythmic effects of vasostatin-1, a recently identified cardioregulatory peptide, in canine models of atrial fibrillation (AF). METHODS AND RESULTS: In 13 pentobarbital-anesthetized dogs bilateral thoracotomies allowed the attachment of multielectrode catheters to superior and inferior pulmonary veins and atrial appendages (AA). Rapid atrial pacing (RAP) was maintained for 6 hours. Each hour, programmed stimulation was performed to determine the window of vulnerability (WOV), a measure of AF inducibility, at all sites. During the last 3 hours, vasostatin-1, 33 nM, was injected into the anterior right (AR) ganglionated plexus (GP) and inferior right (IR) GP every 30 minutes (n = 6). Seven dogs underwent 6 hours of RAP only (controls). At baseline, acetylcholine, 100 mM, was applied on the right AA and AF duration was recorded before and after injection of vasostatin-1, 33 nM, into the ARGP and IRGP. In separate experiments (n = 8), voltage-sinus rate response curves (surrogate for GP function) were constructed by applying high-frequency stimulation to the ARGP with incremental voltages with or without vasostatin-1. Vasostatin-1 significantly decreased the duration of acetylcholine-induced AF (11.0 ± 4.1 vs 5.5 ± 2.6 min, P = 0.02). The cumulative WOV (the sum of individual WOVs) significantly increased (P < 0.0001) during the first 3 hours and decreased toward baseline in the presence of vasostatin-1 (P < 0.0001). Cumulative WOV in controls steadily increased. Vasostatin-1 blunted the slowing of sinus rate with increasing stimulation voltage of ARGP. CONCLUSIONS: Vasostatin-1 suppresses AF inducibility, likely by inhibiting GP function. These data may provide new insights into the role of peptide neuromodulators for AF therapy.

Dissociated pulmonary vein rhythm may predict the acute pulmonary vein reconnection post-isolation in patients with paroxysmal atrial fibrillation.

AIMS: Dissociated pulmonary vein rhythm (PVD) has been taken as a signal of PV isolation, but has been questioned recently; we assessed the relationship between PVD and acute PV reconnection after PV isolation in this study. METHODS AND RESULTS: Eighty-five consecutive patients (52 males; mean age 59±11 years) were referred for catheter ablation of drug-refractory paroxysmal AF. Following PV isolation, the presence and cycle length of PVD were recorded. Pulmonary veins were classified into veins with PVD (Group 1) and veins without PVD (Group 2). Adenosine triphosphate (ATP) was then injected during isoproterenol infusion to reveal dormant conduction gap(s), and PVs were further remapped at 30 min post-isolation. Totally, PVD was observed in 68% (58 of 85) of patients and 34.7% (112 of 323) of PVs. Seventy-nine (24.5%) PVs were found acutely reconnected, including 48 veins revealed by ATP induction [ATP(+)PV] and 64 veins by reassessment after 30 min post-isolation [Time(+)PV]. Time(+)PVs were observed more frequently in Group 1 than those in Group 2 (31.3 vs. 13.7%, P<0.01), but no significant difference was found in the occurrence of ATP(+)PVs between Group 1 and Group 2 (17.9 vs. 13.3%, P=0.27). The sequences of the PVD and the acutely reconnected PV potential were similar in 87.5% of veins. After PV re-isolation, 70% (28 of 40) of previously documented PVD disappeared. CONCLUSION: The occurrence of PVD after PV isolation was closely related to the acute PV reconnection after 30 min post-isolation.

Down-regulation of connexin43 gap junction by serum deprivation in human endothelial cells was improved by (-)-Epigallocatechin gallate via ERK MAP kinase pathway.

Intercellular communication through gap junctions (GJIC) plays an essential role in maintaining the functional integrity of vascular endothelium. Despite emerging evidence suggests that (-)-Epigallocatechin gallate (EGCG) may improve endothelial function. However, its effect on Cx43 gap junction in endothelial cells remains unexplored. Here we investigated the effect of EGCG on connexin43 (Cx43) gap junction in endothelial cells. The levels of Cx43 protein in human umbilical vein endothelial cells (HUVECs) cultured under serum-deprivation 48 h decreased about 50%, accompanied by decreased GJIC. This reduction can be reversed by treatments with EGCG. In addition, EGCG activated ERK, P38, and JNK mitogen-activated protein kinases (MAPKs), which were supposed to participate in the regulation of Cx43. A MEK inhibitor PD98059, but not SB203580 (a p38 kinase inhibitor) or SP600125 (a JNK kinase inhibitor), abolished the effects of EGCG on Cx43 expression and GJIC. Moreover, although both Akt and eNOS phosphorylation were time-dependently augmented by EGCG, neither PI3K inhibitor LY294002 nor eNOS inhibitor L-NAME blocked the effects of EGCG on Cx43 gap junctions. Thus, EGCG attenuated Cx43 down-regulation and impaired GJIC induced by serum deprivation, ERK MAPK Signal transduction pathway appears to be involved in these processes.

Epigallocatechin-3 gallate, a green tea catechin, attenuated the downregulation of the cardiac gap junction induced by high glucose in neonatal rat cardiomyocytes.

AIMS: The remodeling of cardiac gap junctions has been postulated to contribute to the arrhythmias in a diabetic heart. Epigallocatechin-3 gallate (EGCG), a green tea catechin, has recently been recognized for its protection in cardiovascular disease. This study investigated the effect of EGCG on the possible remodeling of gap junctions under high glucose in cultured neonatal rat cardiomyocytes. METHODS: Cardiomyocytes pre-incubated with high glucose (30mM) were co-treated by EGCG. The expression of Connexin43 (Cx43), Cx40 and Cx45 were determined by Western blot and real-time RT-PCR. The function of cells coupling was evaluated by scrape loading dye transfer study. The Mitogen-activated protein kinases (MAPK) were quantified by Western blot. RESULTS: The protein expression of Cx43 was reduced by high glucose (30mM, 72h). Addition of EGCG to high glucose treated cardiomyocytes attenuated the Cx43 reduction in a dose- and time-dependent manner and also recovered the reduced function of cells coupling. The mRNA or protein level of Cx40 and Cx45 showed no significant change by high glucose (30mM, 72h) or EGCG co-treatment (40microM, 24h). Nor did the Cx43 mRNA level. EGCG (40muM) activated the time-dependent phosphorylated Erk, JNK and p38 MAPK. The p38 MAPK inhibitor SB203580 (10microM), however, attenuated the protective effect of EGCG. CONCLUSION: EGCG could attenuate the downregulation of gap junction induced by high glucose in cultured neonatal rat cardiomyocytes. The p38 MAPK pathway was partly involved in this effect of EGCG.

Autonomic denervation using magnetic nanoparticles.

Nanoparticles with their unique physical and biochemical properties, such as modifiable surface functionalization and versatility for carrying various therapeutic payloads, are excellent vehicles for targeted drug delivery. The diffuse nature of cardiovascular diseases presents a great challenge to nanotechnology-based drug delivery therapy. Cardiac arrhythmias, frequently caused by heterogeneity of conduction, repolarization, and cell-cell communication, are particularly sensitive to any therapy that targets the presumed arrhythmogenic myocardium but inadvertently introduces further heterogeneity into the heart. In this review, we focus on an alternative approach that is to target the ganglionated plexi of the cardiac autonomic nervous system responsible for many arrhythmias. These ganglionated plexi, serving as the "integration centers" of the cardiac autonomic nervous system, are located in discrete sites on the epicardial surface and potentially can be targeted by magnetic nanoparticles navigated by externally applied magnetic field.

Early detection of pulmonary vein reconnection after isolation in patients with paroxysmal atrial fibrillation: a comparison of ATP-induction and reassessment at 30 minutes postisolation.

INTRODUCTION: Catheter ablation for paroxysmal AF (PAF) is limited by an unacceptable recurrence rate, mainly due to pulmonary vein (PV) reconnection. Strategies to minimize reconnection include adenosine infusion and also a waiting period of 30 minutes after PV isolation. The aim of the present study was to assess whether these two strategies revealed the same conduction gap. METHODS AND RESULTS: In total, 88 consecutive patients (54 males, mean age of 60 years) with drug refractory PAF underwent circumferential PV isolation (CPVI). After isolation of ipsilateral PVs, with entry and exit block checked using a circular mapping catheter, 20 mg ATP was injected during isoproterenol infusion to reveal dormant conduction gap(s). Unless the reconnection revealed by ATP persisted, PVs were further remapped with the circular mapping catheter at 30 minutes postisolation. Totally, PV reconnection was observed in 56 (64%) patients. 24.3% veins (80/329) were found reconnected. Reassessment at 30 minutes postablation was more efficient as compared to ATP induction (19.8% vs 14.6% for ATP). The agreement between these 2 methods is moderate (kappa value = 0.50). In veins that transiently reconnected after ATP administration and later observed at 30 minutes postablation, 94% (17 of 19) of them were found being reconnected with the same gap. CONCLUSION: Acute PV reconnection is common, occurring in 64% of patients, as detected by adenosine infusion and waiting time. Each shows a unique quality as compared to one another. The combined use of these 2 methods may reduce the AF recurrence rate after CPVI.

Knockout of the tumor necrosis factor a receptor 1 gene can up-regulate erythropoietin receptor during myocardial ischemia-reperfusion injury in mice.

BACKGROUND: Tumor necrosis factor a receptor 1 (TNFalphaR1) plays an important role in the signal pathway of apoptosis. The objective of this study was to investigate the effects of TNFalphaR1 knockout on the up-regulation of erythropoietin receptor (Epo-R) and the coordinated anti-apoptosis functions during myocardial ischemia-reperfusion injury in mice. METHODS: The ischemia-reperfusion injury model for cardiomyocytes was performed by ligating the left circumflex branch artery of TNFalphaR1 knockout (P55(-/-)) C17 B6 mice, as well as wild-type (P55(+/+)) C17 B6 mice. Triphenyltetrazolium chloride (TTC) staining was performed to observe the damaged area of the heart. TUNEL staining and DNA fragmentation were used to identify apoptosis. Mitochondrial Bcl-2 and Bax as well as expression of Epo-R and its downstream genes (Jak-2, stat-5, Akt, IkB-alpha, HIF-1alpha) were measured by Western blotting. The gene knockout mice were assigned into those undergoing the apoptosis surgical model group (KO group), and those subjected to sham operation (KOs group). Similarly, wild-type mice were either exposed to the surgical model (WT group) or subject to a sham operation (WTs group). RESULTS: The myocardial damage ratio of the wild-type group after the operation was significantly higher than that of the knockout group, (50.5 +/- 6.4)% vs (36.9 +/- 6.9)%, P < 0.01. Similarly, TUNEL positive ratio of the wild-type group was significantly higher than that of the knockout group, (63.1 +/- 5.6)% vs (42.1 +/- 4.7)%, P < 0.01. The gray value ratios of Epo-R, Jak-2, stat-5, Akt, IkB-alpha, HIF-1 and mitochondrial Bcl-2 in the KO group were significantly higher than those of the WT group, P < 0.05; however, mitochondrial Bax was significantly lower than that of the WT group significantly (P < 0.05). CONCLUSIONS: Using the ischemia-reperfusion injury model in mice, cardiomyocytes of TNFalphaR1 knockouts exhibited anti-apoptotic characteristics. This information could be used to coordinate the prevention of myocardial apoptosis by up-regulating and activating the Epo-R pathway.