53 research outputs found
The atrial defibrillation threshold of the standard blatrial configuration is markedly reduced when followed by a second shock along the atrial septum
The functional head of the Cambrian radiodontan (stem-group Euarthropoda) Amplectobelua symbrachiata
© The Author(s). 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The attached file is the published version of the article
Ectopic foci do not coâlocate with ventricular epicardial stretch during early acute regional ischemia in isolated pig hearts
Abstract Ectopic activation during early acute regional ischemia may initiate fatal reentrant arrhythmias. However, the origin of this ectopy remains poorly understood. Studies suggest that systolic stretch arising from dyskinesia in ischemic tissue may cause ectopic depolarization due to cardiac mechanosensitivity. The aim of this study was to investigate the link between mechanical stretch and ectopic electrical activation during early acute regional ischemia. We used a recently developed optical mapping technique capable of simultaneous imaging of mechanical deformation and electrical activation in isolated hearts. Eight domestic swine hearts were prepared in left ventricular working mode (LVW), in which the left ventricle was loaded and contracting. In an additional eight nonâworking (NW) hearts, contraction was pharmacologically suppressed with blebbistatin and the left ventricle was not loaded. In both groups, the left anterior descending coronary artery was tied below the first diagonal branch. Positive mechanical stretch (bulging) during systole was observed in the ischemic zones of LVW, but not NW, hearts. During ischemia phase 1a (0â15âmin postâocclusion), LVW hearts had more ectopic beats than NW hearts (median: 19, interquartile range: 10â28 vs. median: 2, interquartile range: 1â6; p = 0.02); but the difference during phase 1b (15â60âmin postâocclusion) was not significant (median: 27, interquartile range: 22â42 vs. median: 16, interquartile range: 12â31; p = 0.37). Ectopic beats arose preferentially from the ischemic border zone in both groups (pâ<â0.01). In LVW hearts, local mechanical stretch was only occasionally coâlocated with ectopic foci (9 of 69 ectopic beats). Despite the higher rate of ectopy observed in LVW hearts during ischemia phase 1a, the ectopic beats generally did not arise by the hypothesized mechanism in which ectopic foci are generated by coâlocal epicardial mechanical stretch
The atrial defibrillation threshold of the standard blatrial configuration is markedly reduced when followed by a second shock along the atrial septum
Noninvasive Activation Imaging of Ventricular Arrhythmias by Spatial Gradient Sparse in Frequency DomainâApplication to Mapping Reentrant Ventricular Tachycardia
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