Single-molecule Localization of Nav1.5 Reveals Different Modes of Reorganization at Cardiomyocyte Membrane Domains.
- 作者列表："Vermij SH","Rougier JS","Agulló-Pascual E","Rothenberg E","Delmar M","Abriel H
:Background - Mutations in the gene encoding the sodium channel Nav1.5 cause various cardiac arrhythmias. This variety may arise from different determinants of Nav1.5 expression between cardiomyocyte domains. At the lateral membrane and T-tubules, Nav1.5 localization and function remain insufficiently characterized. Methods - We used novel single-molecule localization microscopy (SMLM) and computational modeling to define nanoscale features of Nav1.5 localization and distribution at the lateral membrane (LM), the LM groove, and T-tubules (TT) in cardiomyocytes from wild-type (N = 3), dystrophin-deficient (mdx; N = 3) mice, and mice expressing C-terminally truncated Nav1.5 (ΔSIV; N = 3). We moreover assessed TT sodium current by recording whole-cell sodium currents in control (N = 5) and detubulated (N = 5) wild-type cardiomyocytes. Results - We show that Nav1.5 organizes as distinct clusters in the groove and T-tubules which density, distribution, and organization partially depend on SIV and dystrophin. We found that overall reduction in Nav1.5 expression in mdx and ΔSIV cells results in a non-uniform re-distribution with Nav1.5 being specifically reduced at the groove of ΔSIV and increased in T-tubules of mdx cardiomyocytes. A TT sodium current could however not be demonstrated. Conclusions - Nav1.5 mutations may site-specifically affect Nav1.5 localization and distribution at the lateral membrane and T-tubules, depending on site-specific interacting proteins. Future research efforts should elucidate the functional consequences of this redistribution.
: 背景-编码钠通道 Nav1.5 的基因突变引起各种心律失常。该品种可能源于心肌细胞结构域之间 Nav1.5 表达的不同决定因素。在侧膜和 T-小管，Nav1.5 定位和功能仍然没有充分表征。方法-我们使用新型单分子定位显微镜 (SMLM) 和计算建模来定义 Nav1.5 定位和分布在侧膜 (LM) 、 LM 凹槽的纳米级特征,野生型 (N = 3) 肌营养不良蛋白缺陷型 (mdx; N = 3) 小鼠心肌细胞中的 T-小管 (TT),和表达 C 末端截短 Nav1.5 的小鼠 (Δ siv; N = 3)。此外，我们通过记录对照 (N = 5) 和脱管 (N = 5) 野生型心肌细胞的全细胞钠电流来评估 TT 钠电流。结果-我们发现 Nav1.5 在沟和 T 小管中组织为不同的簇，其密度、分布和组织部分依赖于 SIV 和 dystrophin。我们发现，在 mdx 和 Δ siv 细胞中 Nav1.5 表达的总体减少导致不均匀的重新分布，Nav1.5 在 Δ siv 的凹槽处特异性减少，在 mdx 的 T-小管中增加。心肌细胞。然而，不能证明 TT 钠电流。结论-Nav1.5 突变可能位点特异性影响 Nav1.5 在侧膜和 T 小管的定位和分布，这取决于位点特异性相互作用蛋白。未来的研究工作应阐明这种再分配的功能后果。
METHODS:AIMS:Pulmonary vein isolation (PVI) using ablation index (AI) incorporates stability, contact force (CF), time, and power. The CLOSE protocol combines AI and ≤6 mm interlesion distance. Safety concerns are raised about surround flow ablation catheters (STSF). To compare safety and effectiveness of an atrial fibrillation (AF) ablation strategy using AI vs. CLOSE protocol using STSF.,METHODS AND RESULTS:First cluster was treated using AI and second cluster using CLOSE. Procedural data, safety, and recurrence of any atrial tachycardia (AT) or AF >30 s were collected prospectively. All Classes 1c and III anti-arrhythmic drugs (AAD) were stopped after the blanking period. In total, all 215 consecutive patients [AI: 121 (paroxysmal: n = 97), CLOSE: n = 94 (paroxysmal: n = 74)] were included. Pulmonary vein isolation was reached in all in similar procedure duration (CLOSE: 107 ± 25 vs. AI: 102 ± 24 min; P = 0.1) and similar radiofrequency time (CLOSE: 36 ± 11 vs. AI: 37 ± 8 min; P = 0.4) but first pass isolation was higher in CLOSE vs. AI [left veins: 90% vs. 80%; P < 0.05 and right veins: 84% vs. 73%; P < 0.05]. Twelve-month off-AAD freedom of AF/AT was higher in CLOSE vs. AI [79% (paroxysmal: 85%) vs. 64% (paroxysmal: 68%); P < 0.05]. Only four patients (2%) without recurrence were on AAD during follow-up. Major complications were similar (CLOSE: 2.1% vs. AI: 2.5%; P = 0.87).,CONCLUSION:The CLOSE protocol is more effective than a PVI approach solely using AI, especially in paroxysmal AF. In this off-AAD study, 79% of patients were free from AF/AT during 12-month follow-up. The STSF catheter appears to be safe using conventional CLOSE targets.
METHODS:OBJECTIVE:To investigate the role of driver mechanism and the effect of electrogram dispersion-guided driver mapping and ablation in atrial fibrillation (AF) at different stages of progression.,METHODS:A total of 256 consecutive patients with AF who had undergone pulmonary vein isolation (PVI) plus driver ablation or conventional ablation were divided into three groups: paroxysmal atrial fibrillation (PAF; group A, n = 51); persistent atrial fibrillation (PsAF; group B, n = 38); and long standing-persistent atrial fibrillation (LS-PsAF; group C, n = 39). PVI was performed with the guidance of the ablation index. The electrogram dispersion was analyzed for driver mapping.,RESULTS:The most prominent driver regions were at roof (28.0%), posterior wall (17.6%), and bottom (21.3%). From patients with PAF to those with PsAF and LS-PsAF: the complexity of extra-pulmonary vein (PV) drivers including distribution, mean number, and area of dispersion region increased (P < .001). Patients who underwent driver ablation vs conventional ablation had higher procedural AF termination rate (76.6% vs 28.1%; P < .001). With AF progression, the termination rate gradually decreased from group A to group C, and the role of PVI in AF termination was also gradually weakened from group A to group C (39.6%, 7.4%, and 4.3%; P < .001) in patients with driver ablation. At the end of the follow-up, the rate of sinus rhythm maintenance was higher in patients with driver ablation than those with conventional ablation (89.1% vs 70.3%; P < .001).,CONCLUSION:The formation of extra-PV drivers provides an important mechanism for AF maintenance with their complexity increasing with AF progression. Electrogram dispersion-guided driver ablation appears to be an efficient adjunctive approach to PVI for AF treatment.
METHODS:PURPOSE:Whether or not pulmonary vein isolation (PVI) plus left atrial posterior wall isolation (PWI) using contact force (CF) sensing improves the ablation outcome for persistent atrial fibrillation (AF) is unclear. This study compared the outcome of PVI plus PWI and additional non-PV trigger ablation for persistent AF with/without CF sensing. METHODS:This retrospective cohort study analyzed 148 propensity score-matched persistent AF patients (median duration of persistent AF, 8 months (interquartile range, 3-24 months); left atrial diameter, 43 ± 7 mm) undergoing PVI plus PWI and ablation of non-PV triggers provoked by high-dose isoproterenol, including 74 with CF-sensing catheters (CF group) and 74 with conventional catheters (non-CF group). PVI plus PWI with no additional ablation but cavotricuspid isthmus ablation was performed without non-PV triggers in 48 CF patients (65%) and 54 non-CF patients (73%) (P = 0.38). In all other patients, we performed additional ablation of provoked non-PV triggers. RESULTS:The Kaplan-Meier estimate of the rate of freedom from atrial tachyarrhythmia recurrence of antiarrhythmic drugs at 12 months after the single procedure was higher in the CF group than in the non-CF group (85 vs. 70%, log-rank P = 0.030). A multivariable analysis revealed that using CF sensing and non-inducibility of AF from a non-PV trigger after PVI and PWI were significantly associated with a reduced rate of atrial tachyarrhythmia recurrence. CONCLUSIONS:Compared with non-CF sensing, PVI plus PWI and additional non-PV trigger ablation using CF-sensing catheters for persistent AF can reduce the rate of atrial tachyarrhythmia recurrence.