scholarly journals Inhibition of Small-Conductance Calcium-Activated Potassium Current (IK,Ca) Leads to Differential Atrial Electrophysiological Effects in a Horse Model of Persistent Atrial Fibrillation

2021 ◽  
Vol 12 ◽  
Author(s):  
Merle Friederike Fenner ◽  
Giulia Gatta ◽  
Stefan Sattler ◽  
Marion Kuiper ◽  
Eva Melis Hesselkilde ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Cycle Length ◽  
Persistent Atrial Fibrillation ◽  
High Density ◽  
Contact Mapping ◽  
Surface Ecg ◽  
Divergent Behavior ◽  
The Right ◽  
Propagation Properties ◽  
Small Conductance

BackgroundSmall-conductance Ca2+-activated K+ (KCa2) channels have been proposed as a possible atrial-selective target to pharmacologically terminate atrial fibrillation (AF) and to maintain sinus rhythm. However, it has been hypothesized that the importance of the KCa2 current—and thereby the efficacy of small-conductance Ca2+-activated K+ current (IK,Ca) inhibition—might be negatively related to AF duration and the extent of AF-induced remodeling.Experimental Approach and MethodsTo address the hypothesis of the efficacy of IK,Ca inhibition being dependent on AF duration, the anti-arrhythmic properties of the IK,Ca inhibitor NS8593 (5 mg/kg) and its influence on atrial conduction were studied using epicardial high-density contact mapping in horses with persistent AF. Eleven Standardbred mares with tachypacing-induced persistent AF (42 ± 5 days of AF) were studied in an open-chest experiment. Unipolar AF electrograms were recorded and isochronal high-density maps analyzed to allow for the reconstruction of wave patterns and changes in electrophysiological parameters, such as atrial conduction velocity and AF cycle length. Atrial anti-arrhythmic properties and adverse effects of NS8593 on ventricular electrophysiology were evaluated by continuous surface ECG monitoring.ResultsIK,Ca inhibition by NS8593 administered intravenously had divergent effects on right and left AF complexity and propagation properties in this equine model of persistent AF. Despite global prolongation of AF cycle length, a slowing of conduction in the right atrium led to increased anisotropy and electrical dissociation, thus increasing AF complexity. In contrast, there was no significant change in AF complexity in the LA, and cardioversion of AF was not achieved.ConclusionsIntra-atrial heterogeneity in response to IK,Ca inhibition by NS8593 was observed. The investigated dose of NS8593 increased the AF cycle length but was not sufficient to induce cardioversion. In terms of propagation properties during AF, IK,Ca inhibition by NS8593 led to divergent effects in the right and left atrium. This divergent behavior may have impeded the cardioversion success.

scholarly journals 1157Sequential ultra-high density contact mapping shows increase of left atrial organization during persistent atrial fibrillation ablation

EP Europace ◽  
2017 ◽  
Vol 19 (suppl_3) ◽  
pp. iii245-iii245
Author(s):  
DG. Latcu ◽  
A. Amourha ◽  
B. Enache ◽  
SS. Bun ◽  
T. Delassi ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrial ◽  
Persistent Atrial Fibrillation ◽  
High Density ◽  
Atrial Fibrillation Ablation ◽  
Contact Mapping

Nonreentrant focal activations in pulmonary veins in canine model of sustained atrial fibrillation

2002 ◽  
Vol 283 (3) ◽  
pp. H1244-H1252 ◽  
Author(s):  
Shengmei Zhou ◽  
Che-Ming Chang ◽  
Tsu-Juey Wu ◽  
Yasushi Miyauchi ◽  
Yuji Okuyama ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrium ◽  
Right Atrium ◽  
Cycle Length ◽  
Pulmonary Veins ◽  
Posterior Wall ◽  
Canine Model ◽  
Anterior Wall ◽  
High Density ◽  
The Right

Repetitive rapid activities are present in the pulmonary veins (PVs) in dogs with pacing-induced sustained atrial fibrillation (AF). The mechanisms are unclear. We induced sustained (>48 h) AF by rapidly pacing the left atrium (LA) in six dogs. High-density computerized mapping was done in the PVs and atria. Results show repetitive focal activations in all dogs and in 12 of 18 mapped PVs. Activation originated from the middle of the PV and then propagated to the LA and distal PV with conduction blocks. The right atrium (RA) was usually activated by a single large wavefront. Mean AF cycle length in the PVs (left superior, 82 ± 6 ms; left inferior, 83 ± 6 ms; right inferior, 83 ± 4 ms) and LA posterior wall (87 ± 5 ms) were significantly ( P < 0.05) shorter than those in the LA anterior wall (92 ± 4 ms) and RA (107 ± 5 ms). PVs in normal dogs did not have focal activations during induced AF. No reentrant wavefronts were demonstrated in the PVs. We conclude that nonreentrant focal activations are present in the PVs in a canine model of pacing-induced sustained AF.

scholarly journals P294Rotating drivers identification with sequential ultra-high density contact mapping of persistent atrial fibrillation

EP Europace ◽  
2017 ◽  
Vol 19 (suppl_3) ◽  
pp. iii44-iii45 ◽  
Author(s):  
DG. Latcu ◽  
A. Amourha ◽  
B. Enache ◽  
SS. Bun ◽  
T. Delassi ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Persistent Atrial Fibrillation ◽  
High Density ◽  
Contact Mapping

Fibrillation cycle length predicts cardiovascular events in patients with long-standing persistent atrial fibrillation

2021 ◽  
Author(s):  
Hironori Nakamura ◽  
Shinichi Niwano ◽  
Hidehira Fukaya ◽  
Jun Kishihara ◽  
Akira Satoh ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Cardiovascular Events ◽  
Cycle Length ◽  
Persistent Atrial Fibrillation

Abstract 15570: Direct Evidence of Endo-Epicardial Dissociation of the Atrial Wall in Patients With Longstanding Persistent Atrial Fibrillation

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Natasja de Groot ◽  
Lisette vd Does ◽  
Ameeta Yaksh ◽  
Paul Knops ◽  
Pieter Woestijne ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Direct Evidence ◽  
Persistent Atrial Fibrillation ◽  
Right Atrial ◽  
Electrode Arrays ◽  
Atrial Wall ◽  
Ablative Therapies ◽  
Epicardial Layer ◽  
Right Atrial Appendage ◽  
The Right

Introduction: Transition of paroxysmal to longstanding persistent atrial fibrillation (LsPAF) is associated with progressive longitudinal dissociation in conduction and a higher incidence of focal fibrillation waves. The aim of this study was to provide direct evidence that the substrate of LsPAF consists of an electrical double-layer of dissociated waves, and that focal fibrillation waves are caused by endo-epicardial breakthrough. Hypothesis: LsPAF in humans is caused by electrical dissociation of the endo- and epicardial layer. Methods: Intra-operative mapping of the endo- and epicardial right atrial wall was performed in 9 patients with induced (N=4), paroxysmal (N=1), persistent (N=2) or longstanding-persistent AF (N=2). A clamp of two rectangular electrode-arrays (128 electrodes; inter-electrode distance 2mm) was introduced through an incision in the right atrial appendage. Series of 10 seconds of AF were analyzed and the incidence of endo-epicardial dissociation (≥15ms) was determined for all 128 endo-epicardial recording sites. Results: In patients with LsPAF the averaged degree of endo-epicardial dissociation was highest (24.9% vs. 5.9%). Using strict criteria for breakthrough (presence of an opposite wave within 4mm and <15ms before the origin of the focal wave), the far majority (77%) of all focal fibrillation waves could be attributed to endo-epicardial excitation. Conclusions: During LsPAF considerable differences in activation of the right endo- and epicardial wall exist. Endo-epicardial fibrillation waves that are out of phase, may conduct transmurally and create breakthrough waves in the opposite layer. This may explain the high persistence of AF and the low succes rate of ablative therapies in patients with LsPAF.

Sign in / Sign up

Export Citation Format

Share Document