Fluoroscopy usage in contemporary interventional electrophysiology: Insights from a European registry

BackgroundFluoroscopy has been an essential part of every electrophysiological procedure since its inception. However, till now no clear standards regarding acceptable x‐ray exposure nor recommendation how to achieve them have been proposed.HypothesisCurrent norms and quality markers required for optimal clinical routine can be identified.MethodsCenters participating in this Europe‐wide multicenter, prospective registry were requested to provide characteristics of the center, operators, technical equipment as well as procedural settings of consecutive cases.ResultsTwenty‐five centers (72% university clinics, with a mean volume of 526 ± 348 procedures yearly) from 14 European countries provided data on 1788 cases [9% diagnostic procedures (DP), 38% atrial fibrillation (AF) ablations, 44% other supraventricular (SVT) ablations, and 9% ventricular ablations (VT)] conducted by 95 operators (89% male, 41 ± 7 years old).Mean dose area product (DAP) and time was 304 ± 608 cGy*cm², 3.6 ± 4.8 minutes, 1937 ± 608 cGy*cm², 15.3 ± 15.5 minutes, 805 ± 1442 cGy*cm², 10.6 ± 10.7 minutes, and 1277 ± 1931 cGy*cm², 10.4 ± 12.3 minutes for DP, AF, SVT, and VT ablations, respectively. Seven percent of all procedures were conducted without any use of fluoroscopy.Procedures in the lower quartile of DAP were performed more frequently by female operators (OR 1.707, 95%CI 1.257‐2.318, P = .001), in higher‐volume center (OR 1.001 per one additional procedure, 95%CI 1.000‐1.001, P = .002), with the use of 3D‐mapping system (OR 2.622, 95%CI 2.053‐3.347, P < .001) and monoplane x‐ray system (OR 2.945, 95%CI 2.149‐4.037, P < .001).ConclusionExposure to ionizing radiation varies widely in daily practice for all procedure. Significant opportunities for harmonization of exposure toward the lower range has been identified.     

Inferior Vena Cava-Tricuspid Annulus Isthmus is a Critical Site of Unidirectional Block During the Induction of Common Atrial Flutter

Background: Until recently no clinical studies had reported precise right atrium (RA) mapping when performing induction of atrial flutter (AFI). We studied the mode of tachycardia initiation in 16 patients (pts) referred for radiofrequency (RF) AFl ablation. AFl induction was performed at the beginning of the procedure (n &equals; 10), or after previous AFl termination during RF delivery (n &equals; 6). Detailed analysis of AFl initiation was provided by duodecapolar (Halo) and multipolar catheters positioned in the peritricuspidian region at the lateral right atrial wall (LRA), the inferior vena cavatricuspid annulus (IVC-TA) isthmus and the interatrial septum. Induction was obtained during incremental pacing (IAP) (15 pts) or programmed stimulation (1 pt) from the proximal coronary sinus (PCS).Results: Atrial flutter with counterclockwise (CCW) RA rotation was induced in all pts by PCS pacing. During PCS IAP, at long pacing cycle lengths, impulse propagated in a clockwise (CW) direction through the IVC-TA isthmus and then upward at low (L) LRA. This led to a collision at the mid LRA with another wave front propagating in a CCW direction at the septum. IAP from PCS induced a progressive delay of propagation at the IVC-TA isthmus resulting in a prolongation of the PCS-Mid Isthmus interval from 85&plusmn;29 to 151&plusmn;42 msec. At same pacing cycle lengths (CL), the PCS-HLRA interval was comparatively less prolonged, from 75&plusmn;12 to 105&plusmn;18 msec, p &equals; 0.0007. This preferential slowing of conduction between PCS and mid isthmus, during IAP from PCS, was associated with a displacement of the zone of collision to the Low LRA. Finally a CW functional block occurred at the IVC-TA isthmus and CCW AFl was induced through a period of transient concealed entrainment. The paced CL required to initiate flutter ranged from 290 to 180 msec and the mean CL of induced atrial flutter was 254&plusmn;27 msec.Conclusions: The IVC-TA isthmus has decremental properties and exhibits wenckebach phenomenon during incremental PCS pacing. Initiation of a counterclockwise flutter by PCS pacing is associated with appearance of a functional unidirectional block at the IVC-TA isthmus.     

J波与J波综合征

J波是指心电图上QRS波与ST段之间的圆顶状或驼峰状电位变化。新近临床研究表明，在早期复极综合征、Brugada综合征和特发性心室颤动等心电图中，均存在J波形态、时限和幅度的显著改变，上述与J波密切相关的一系列临床综合征统称为J波综合征。本文详尽阐述了J波的细胞电生理和离子流机制，分析了早期复极综合征、Brugada综合征、心电图下壁导联高大J波相关的心脏性猝死的临床特点及内在机制。     

A Novel KCNJ13 Nonsense Mutation and Loss of Kir7.1 Channel Function Causes Leber Congenital Amaurosis (LCA16)

Mutations in the KCNJ13 gene that encodes the inwardly rectifying potassium channel Kir7.1 cause snowflake vitreoretinal degeneration (SVD) and leber congenital amaurosis (LCA). Kir7.1 controls the microenvironment between the photoreceptors and the retinal pigment epithelium (RPE) and also contributes to the function of other organs such as uterus and brain. Heterologous expressions of the mutant channel have suggested a dominant‐negative loss of Kir7.1 function in SVD, but parallel studies in LCA16 have been lacking. Herein, we report the identification of a novel nonsense mutation in the second exon of the KCNJ13 gene that leads to a premature stop codon in association with LCA16. We have determined that the mutation results in a severe truncation of the Kir7.1 C‐terminus, alters protein localization, and disrupts potassium currents. Coexpression of the mutant and wild‐type channel has no negative influence on the wild‐type channel function, consistent with the normal clinical phenotype of carrier individuals. By suppressing Kir7.1 function in mice, we were able to reproduce the severe LCA electroretinogram phenotype. Thus, we have extended the observation that Kir7.1 mutations are associated with vision disorders to include novel insights into the molecular mechanism of disease pathobiology in LCA16.     

Angiotensin 1‐7 modulates electrophysiological characteristics and calcium homoeostasis in pulmonary veins cardiomyocytes via MAS/PI3K/eNOS signalling pathway

Background

Atrial fibrillation (AF) is the most common sustained arrhythmia, and pulmonary veins (PVs) play a critical role in triggering AF. Angiotensin (Ang)‐(1‐7) regulates calcium (Ca²⁺) homoeostasis and also plays a critical role in cardiovascular pathophysiology. However, the role of Ang‐(1‐7) in PV arrhythmogenesis remains unclear.

Materials and methods

Conventional microelectrodes, whole‐cell patch‐clamp and the fluo‐3 fluorimetric ratio technique were used to record ionic currents and intracellular Ca²⁺ in isolated rabbit PV preparations and in single isolated PV cardiomyocytes, before and after administration of Ang‐(1‐7).

Results

Ang (1‐7) concentration dependently (0.1, 1, 10 and 100 nmol/L) decreased PV spontaneous electrical activity. Ang‐(1‐7) (100 nmol/L) decreased the late sodium (Na⁺), L‐type Ca²⁺ and Na⁺‐Ca²⁺ exchanger currents, but did not affect the voltage‐dependent Na⁺ current in PV cardiomyocytes. In addition, Ang‐(1‐7) decreased intracellular Ca²⁺ transient and sarcoplasmic reticulum Ca²⁺ content in PV cardiomyocytes. A779 (a Mas receptor blocker, 3 μmol/L), L‐NAME (a NO synthesis inhibitor, 100 μmol/L) or wortmannin (a specific PI3K inhibitor, 10 nmol/L) attenuated the effects of Ang‐(1‐7) (100 nmol/L) on PV spontaneous electric activity.

Conclusion

Ang‐(1‐7) regulates PV electrophysiological characteristics and Ca²⁺ homoeostasis via Mas/PI3K/eNOS signalling pathway.     

Is extensive atrial fibrosis in the setting of heart failure associated with a reduced atrial fibrillation burden?

Atrial fibrillation (AF) affects 10–50% of patients with chronic heart failure (HF) and is associated with poor long‐term prognosis. AF is commonly associated with atrial structural remodeling (ASR), principally characterized by atrial dilatation and fibrosis. However, the occurrence of AF in the full spectrum of ASR encountered in patients with HF is poorly defined. Experimental studies have presented evidence that extensive ASR can be accompanied with a reduced burden of AF, secondary to a prominent depression of atrial excitability. This reduction in AF burden is associated with severe atrial fibrosis rather than with dilatation. Clinical studies of patients with HF point to the possibility that advanced ASR is associated with a less frequent AF occurrence than moderate ASR. Our goal in this review is to introduce the hypothesis that AF is less likely to occur in severe versus moderate atrial ASR in the setting of HF and that it is severe atrial fibrosis‐associated depression of atrial excitability that reduces AF burden.     

Entrapment of diagnostic catheter within Advisor HD grid mapping catheter

The potential for catheter entanglement with the HD Grid mapping catheter is explicitly stated in the manufacturer's product manual. A case of an entrapped 6 French quadripolar diagnostic catheter within an HD Grid mapping catheter is presented. We discuss the diagnosis, management, and resolution of this complication in our patient. The patient's arrhythmia was successfully eliminated, and no vascular complication in the postprocedural setting nor arrhythmia recurrence at follow-up were observed. Strategies to prevent and safely manage this complication, while salvaging access, are also discussed.