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Planar Laser Induced Fluorescence methods, in particular in their Inhibited version (I-PLIF) are powerful tools to measure local scalar values in various types of flows. The most commonly used LIF methods are intensity-based: Scalar value is extracted from fluoresced light intensity information. However such methods are prone to error when used in challenging configurations (multiphase flows, non-optically-thin systems, etc). In this short paper, the systematic error on concentration measurement in a dissolved gas boundary layer caused by scalar dependency of the extinction coefficient is discussed, in the context of a non-optically thin system with significant out-of-field absorption. Results of single color I pH - P L I F measurements are compared to I pH r - P L I F (ratiometric) measurements for which the out-of-field absorption is intrinsically accounted for. An empirical correction based on first order concentration statistics derived from ratiometric measurements is proposed. It is used to demonstrate that the oversight of out-of-field absorption in intensity-based methods can lead to significant error on the scalar measurements inside the boundary layer. [ABSTRACT FROM AUTHOR]

Background: Transseptal puncture to achieve left atrial access is necessary for many cardiac procedures, including atrial fibrillation ablation. More recently, there has been an increasing need for left atrial access using large caliber sheaths, which increases risk of perforation associated with the initial advancement into the left atrium. We compared the effectiveness of a radiofrequency needle-based transseptal system versus conventional needle for transseptal access.Methods: This prospective controlled trial randomized 161 patients with symptomatic paroxysmal atrial fibrillation undergoing cryoballoon pulmonary vein isolation to transseptal access with a commercially available transseptal system (radiofrequency needle plus stiff pigtail wire; RF + Pigtail group) versus conventional transseptal access (standard group). The primary outcome was time required for left atrial access. Secondary outcomes included failure of the assigned transseptal system, radiation exposure, and complications.Results: The median transseptal puncture time was significantly shorter using the radiofrequency needle plus stiff pigtail wire transseptal system compared with conventional transseptal (840 ± 323 vs. 956 ± 407 s, P = 0.0489). Compared to conventional transseptal puncture, fewer transseptal attempts were required (1.0 ± 0.5 RF applications vs. 1.3 ± 0.8 mechanical punctures, P = 0.0123) and the fluoroscopy time was significantly shorter (72.0 [IQR 48.0, 129.0] vs. 93.0 [IQR 60.0, 171.0] s, P = 0.0490) with the radiofrequency needle plus stiff pigtail wire transseptal system. Failure to achieve transseptal LA access with the assigned system was rarely observed (1.3% vs. 5.7%, P = 0.2192). There were no procedural complications observed with either system.Conclusions: The use of a radiofrequency needle plus stiff pigtail wire resulted in shorter time to left atrial access and reduced fluoroscopy time compared to left atrial access using conventional transseptal equipment.Trial Registration: ClinicalTrials.gov identifier NCT03199703. [ABSTRACT FROM AUTHOR]

Background or purpose: We report our single-center experience with percutaneous left atrial appendage closure (LAAC) in patients with non-valvular atrial fibrillation (NVAF) and primary hemostasis disorders (HD). Methods: Consecutive patients with primary HD who underwent a percutaneous LAAC were included. Baseline characteristics, procedural data, and clinical outcomes were prospectively collected and compared with the overall LAAC cohort without HD. Results: Since 2013, among 229 LAAC, 17 patients (7%) had a primary HD: thrombocytopenia (n = 5), myelodysplastic syndrome (n = 6), von Willebrand syndrome (n = 4), type A hemophilia (n = 1), and dysfibrinogenemia (n = 1). The HD population's age ranged from 61 to 87 years, and the median CHA2DS2VASc was 5. Periprocedural plasmatic management was required in 47% of patients. The immediate LAAC implantation success rate was 100%. Patients received a direct oral anticoagulant (DOA) (n = 9), dual antiplatelet (n = 6), aspirin (n = 1), or no therapy (n = 1) during the first six postoperative weeks, followed with single antiplatelet (n = 16) or no therapy (n = 1) during lifelong. After 20 months, the technical success rate and procedural success rate were 100% and 94%. Zero device-/procedure-related complication and only one life-threatening bleeding occurred. Compared to patients without HD (n = 212), a baseline history of bleeding was less frequent (53% vs 91%, p < 0.001), and more patients received a perioperative blood transfusion (47% vs 4%, p < 0.001) in the HD group. The efficacy and safety outcomes did not differ between HD and non-HD cohorts. Conclusions: Percutaneous LAAC in primary HD carriers appeared as safe and as effective as in overall LAAC population for stroke and bleeding prevention at midterm follow-up. Percutaneous left atrial appendage closure in patients with atrial fibrillation and primary hemostasis disorders. The percutaneous LAAC in primary hemostasis disorders and AF carriers requires a multidisciplinary approach. Cardiologist, anesthesiologist, and hematologist discussion is a cornerstone to assess anticoagulant contraindication, LAAC feasibility, periprocedural management, and follow-up (high). This multidisciplinary care is illustrated by the case of a 61-year-old male with hemophilia type A and recurrent hemarthrosis. Pre-LAAC assessment confirmed procedural indication and cactus LAA anatomy (left). After plasmatic management with factor VIII infusion, a WATCHMAN™ no. 21 was successfully implanted (middle). During follow-up, without antithrombotic regime, no ischemic or hemorrhagic complication occurred (right). LAA, left atrial appendage; LAAC, left atrial appendage closure; TEE, transesophageal echocardiography. Percutaneous LAAC in primary HD carriers appeared as safe and as effective as in overall LAAC population for stroke and bleeding prevention at midterm follow-up. [ABSTRACT FROM AUTHOR]

The study of turbulence in complex fluids is of great interest in many environmental and industrial applications, in which the interactions between liquid phase rheology, turbulence, and other phenomena such as mixing or heat and mass transfer have to be understood. Oscillating grid stirred tanks have been used for many purposes in research involving turbulence. However, the mechanisms of turbulence production by the oscillating grid itself have never been studied, and oscillating grid turbulence (OGT) remained undescribed in non-Newtonian, shear-thinning, dilute polymer solutions until recently (Lacassagne et al., in Phys Fluids 31(8):083,102, 2019). The aim of this paper is to study the influence of the shear-thinning property of dilute polymer solutions (DPS), such as xanthan gum (XG), on mean flow, oscillatory flows, and turbulence around an oscillating grid. Liquid phase velocity is measured by particle image velocimetry (PIV) in a vertical plane above the central grid bar. Mean, oscillatory and turbulent components of the velocity fields are deduced by triple Hussain–Reynolds decomposition based on grid phase-resolved measurements. Outside of the grid swept region, the amplitude of oscillatory fluctuations quickly become negligible compared to that of turbulent fluctuations, and the triple and classical Reynolds decomposition become equivalent. Oscillatory jets and wakes behind the grid and their interactions are visualized. Turbulent (Reynolds) and oscillatory stresses are used to evidence a modification of oscillatory flow and turbulence intensity repartition in and around the grid swept region. Energy transfer terms between mean, oscillatory and turbulent flows are estimated and used to describe turbulence production in the grid swept region. Energy is injected by the grid into the oscillatory component. In water, it is transferred to turbulence mostly inside the grid swept region. In DPS, oscillatory flow persists outside of the grid swept zone. Energy is transferred not only to turbulence , in the grid swept region, and far from the tank's walls, but also to the mean flow, leading to an enhancement of the latter. Mean flow production and enhancement mechanisms are explainable by oscillatory jet variable symmetry and intensity, and by time- and space-variable viscosity. Backward transfer from turbulence to oscillatory flow is also evidenced in DPS. Finally, using phased root mean square (rms) values of turbulent velocity fluctuations, it is shown that in water, the decay of turbulence intensity behind an oscillating grid can be related to the decay of fixed grid turbulence for specific grid positions, a result no longer valid in DPS. [ABSTRACT FROM AUTHOR]

Purpose: Percutaneous left atrial appendage (LAA) closure has become a valid alternative to anticoagulation therapy for the prevention of thromboembolic events in patients with atrial fibrillation (AF). However, scarce data exist on the impact of LAA closure on left atrial and ventricular function. We sought to assess the acute hemodynamic changes associated with percutaneous LAA closure in patients with paroxysmal AF.Methods: The study population consisted of 31 patients (mean age 73 ± 10 years; 49% women) with paroxysmal AF who underwent successful percutaneous LAA closure. All patients were in sinus rhythm and underwent 2D transthoracic echocardiography at baseline and the day after the procedure. A subset of 14 patients underwent preprocedural cardiac computed tomography (CT) with 3D LA and LAA reconstruction.Results: Left ventricular systolic function parameters and LA volumetric indexes remained unchanged after the procedure. No significant changes in left ventricular stroke volume (72.4 ± 16.0 vs. 73.3 ± 15.7 mL, p = 0.55) or LA stroke volume (total 15.6 ± 4.2 vs. 14.6 ± 4.2 mL, p = 0.21; passive 9.0 ± 2.8 vs. 8.3 ± 2.6 mL, p = 0.31; active 10.3 ± 5.6 vs. 10.0 ± 6.4 mL, p = 0.72) occurred following LAA closure. Mean ratio of LAA to LA volume by 3D CT was 10.2 ± 2.3%. No correlation was found between LAA/LA ratio and changes in LA stroke volume (r = 0.35, p = 0.22) or left ventricular stroke volume (r = 0.28, p = 0.33).Conclusions: The LAA accounts for about 10% of the total LA volume, but percutaneous LAA closure did not translate into any significant changes in LA and left ventricular function. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to evaluate the late clinical outcomes of percutaneous LAA closure in patients with atrial fibrillation (AF) and contraindication to oral anticoagulation.Methods: Consecutive AF patients with contraindications to oral anticoagulation who underwent successful LAA closure between December 2008 and March 2013 at four centers were included.Results: A total of 101 patients (median age 76 [IQR 69-80] years, 48% women, mean CHA2DS2-VASc 5 ± 2; HAS-BLED 4 ± 1) were included. Eighty-six (85.1%) patients received an Amplatzer Cardiac Plug/Amulet device and 15 (14.9%) patients a Watchman device. The mean follow-up period was 4 ± 1 years. During 358.6 patient-years of follow-up, 7 (6.9%) patients suffered a major stroke (2 cases per 100 person-years; expected rate: 6.2 cases per 100 person-years), and 20 (19.8%) patients experienced at least one episode of major bleeding (6.4 cases per 100 person-years; expected rate: 9.0 cases per 100 person-years). There were no cases of late adverse events related to the device. A total of 34 (33.7%) patients died during follow-up (9.5 cases per 100 person-years). Older age, male sex, low ejection fraction, and chronic kidney disease were identified as predictive factors of late mortality.Conclusions: Percutaneous LAA closure is safe and effective in the long term in patients with AF with contraindications to anticoagulation. However, a high long-term mortality rate was observed in this high-risk population. Comprehensive patient assessment prior to undergoing LAA closure should identify patients in whose comorbidities limit their overall prognosis. [ABSTRACT FROM AUTHOR]

Background and purpose: Riata defibrillation leads are susceptible to conductor externalization. The point prevalence of insulation defect in Riata leads is up to 33 %, but prospective data concerning incidence of new lead abnormalities are lacking. The purpose of our study was to determine the annual incidence of new conductor externalizations and electrical lead failure. Methods: A prospective observational study was conducted at a single tertiary center. One hundred forty-one patients were followed over 12 months. A posterior-anterior (PA)/lateral chest x-ray (CXR) with zooming was performed at baseline and at 12 months to screen for conductor externalization. Electrical abnormalities and clinical outcome were also assessed. Results: The overall incidence of new insulation defects was 8.5 % at 12 months. High-risk leads for new conductor externalization were lead models 1580, 1582, and 1590 with an annual rate of 11.9, 11.1, and 10 %, respectively. New conductor externalizations were three times more common in 8 Fr leads compared to 7 Fr leads. The overall incidence of new electrical dysfunction was 6.4 % at 12 months. Electrical dysfunction was significantly higher in abnormal leads (25 % [3/12], 4.7 % [6/129]; p = 0.03) and mostly driven by high ventricular pacing thresholds. There was no difference in inappropriate shock or failure of high-voltage therapy. Conclusion: The annual incidence of new insulation defects in Riata leads is much higher than previously reported. Lead models 1580, 1582, and 1590 are at highest risk for new conductor externalization. Electrical dysfunction in Riata leads is also much higher than reported and is associated with conductor externalization. [ABSTRACT FROM AUTHOR]

Purpose: Atrioesophageal fistula (AEF) is an infrequent complication of radiofrequency (RF) ablation for atrial fibrillation (AF). The aim of this study was to determine the prevalence and operator-dependent factors associated with AEF using a nationwide survey of electrophysiologists (EP). Methods: Thirty-eight EPs performing AF ablation between 2008 and 2012 were invited to complete a web-based questionnaire assessing the prevalence and factors associated with AEF. Results: Responses were obtained from 25 EPs (68 %) accounting for 7,016 AF ablations. Five cases of proven AEF (0.07 %) were reported. Operators who reported AEF [AEF (+)] more often used general anesthesia (GA) [90 % AEF (+) vs. 44 % AEF (−), p = 0.046]. AEF (+) operators were also more likely to be users of the non-brushing technique in the posterior wall of the LA [5 (100 %) AEF (+) vs. 5 (25 %) AEF (−), p = 0.005]. The combined usage of GA and non-brushing technique during LA posterior wall ablation had a strong association with AEF (+) operators [4 (80 %) AEF (+) vs. 2 (10 %) AEF (−), p = 0.002]. There was a trend towards higher maximal RF energy setting in the posterior wall [47.4 + 7.6 AEF (+) vs. 40.2 + 8 AEF (−), p = 0.09]. Other procedure parameters were similar. Conclusions: The reported prevalence of AEF among Canadian AF ablators is 0.07 %. AEF was associated with high mortality. The use of GA and non-brushing movements during posterior wall ablation were two factors associated with AEF. [ABSTRACT FROM AUTHOR]

Purpose: Patients undergoing left atrial ablation require transseptal puncture, which can be challenging, even for experienced physicians. This study compared the efficacy and safety of radiofrequency (RF) energy transseptal punctures to conventional approach. Methods: Patients requiring transseptal puncture for left atrial access were included using either conventional approach or the NRG™ RF transseptal needle as first attempt. Procedure time for transseptal access, fluoroscopy time, crossover, and safety of both techniques were compared. Results: A total of 241 transseptal punctures were performed in 148 consecutive patients (114 men, 54 ± 10 years, left atrial volume 32 ± 10 ml/m) who underwent 157 procedures with left atrial access, mainly for atrial fibrillation. It was a repeat transseptal procedure in 49 patients. Procedures were guided by transesophageal echocardiography. RF transseptal puncture was planned in 119 procedures. RF was delivered in 98 procedures (82%) for 139/187 punctures: 48 punctures did not require RF, including 25 punctures performed by exposing the needle tip, 22 through patent foramen ovale, and 1 RF delivery failure by the generator. Average time for RF transseptal was 4.8 ± 2.8 min compared to 7.5 ± 8.5 min for conventional approach ( p = 0.045). Fluoroscopy time was 1.8 ± 1.3 min for RF transseptal and 2.9 ± 2.8 min for standard approach ( p = 0.043). Four patients required crossover to RF transseptal needle in the conventional group ( p = 0.003). One tamponade occurred at the end of procedure in a patient using the RF needle, and one interatrial septum dissection with aortic root hematoma occurred in the conventional group. Conclusions: Transseptal needle puncture using RF energy can be performed safely and quickly under imaging guidance. [ABSTRACT FROM AUTHOR]

Non-synonymous single nucleotide polymorphisms (SNPs) in the KCNA5/hKv1.5 gene, which encodes for a voltage-gated K+ channel responsible for the I Kur current in the human atria, have been recently reported. To gain further knowledge on potential influence of hKv1.5 SNPs, we searched for their presence in a specific population of 96 French-Canadians and characterized electrophysiological properties of the variants in two cell lines. The presumed promoter (−83 bp) and coding regions were sequenced. We found three heterozygous SNPs: R87Q, A251T, and P307S. Functional analysis of SNPs transfected in Chinese hamster ovary (CHO) cells showed that both R87Q and P307S diminished the inactivation amplitude (e.g., at +60 mV, amplitudes were 89±26, 23±4, and 22±7 pA/pF for the wild type, R87Q and P307S, respectively; n=8, 6, and 8, respectively). Inactivation was slowed with these variants (e.g., τ fast at +50 mV were 270±48, 490±66, and 340±45 ms for the wild type, R87Q, and P307S, respectively) while R87Q additionally accelerated the rate of hKv1.5 channel opening. A dominant-negative effect was observed for R87Q but not for P307S. SNPs properties were not reproduced when expressed in the HEK293 cell line, suggesting that the regulatory β-subunit present in CHO cells (and the human heart) is essential for the SNPs effects that we have observed. [ABSTRACT FROM AUTHOR]