Cardiac intramural electrical mapping reveals focal delays but no conduction velocity slowing in the peri-infarct region.

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dc.contributor.author Trew, Mark L
dc.contributor.author Engelman, Zoar J
dc.contributor.author Caldwell, Bryan J
dc.contributor.author Lever, Nigel A
dc.contributor.author LeGrice, Ian J
dc.contributor.author Smaill, Bruce H
dc.coverage.spatial United States
dc.date.accessioned 2021-08-20T01:24:38Z
dc.date.available 2021-08-20T01:24:38Z
dc.date.issued 2019-10
dc.identifier.citation American journal of physiology. Heart and circulatory physiology 317(4):H743-H753 Oct 2019
dc.identifier.issn 0363-6135
dc.identifier.uri https://hdl.handle.net/2292/56102
dc.description.abstract Altered electrical behavior alongside healed myocardial infarcts (MIs) is associated with increased risk of sudden cardiac death. However, the multidimensional mechanisms are poorly understood and described. This study characterizes, for the first time, the intramural spread of electrical activation in the peri-infarct region of chronic reperfusion MIs. Four sheep were studied 13 wk after antero-apical reperfusion infarction. Extracellular potentials (ECPs) were recorded in a ~20 × 20-mm<sup>2</sup> region adjacent to the infarct boundary (25 plunge needles <0.5-mm diameter with 15 electrodes at 1-mm centers) during multisite stimulation. Infarct geometry and electrode locations were reconstructed from magnetic resonance images. Three-dimensional activation spread was characterized by local activation times and interpolated ECP fields (<i>n</i> = 191 records). Control data were acquired in 4 non-infarcted sheep (<i>n</i> = 96 records). Electrodes were distributed uniformly around 15 ± 5% of the intramural infarct boundary. There were marked changes in pacing success and ECP morphology across a functional border zone (BZ) ±2 mm from the boundary. Stimulation adjacent to the infarct boundary was associated with low-amplitude electrical activity within the BZ and delayed activation of surrounding myocardium. Bulk tissue depolarization occurred 3.5-14.6 mm from the pacing site for 39% of stimuli with delays of 4-37 ms, both significantly greater than control (<i>P</i> < 0.0001). Conduction velocity (CV) adjacent to the infarct was not reduced compared with control, consistent with structure-only computer model results. Insignificant CV slowing, irregular stimulus-site specific activation delays, and obvious indirect activation pathways strongly suggest that the substrate for conduction abnormalities in chronic MI is predominantly structural in nature.<b>NEW & NOTEWORTHY</b> Intramural in vivo measurements of peri-infarct electrical activity were not available before this study. We use pace-mapping in a three-dimensional electrode array to show that a subset of stimuli in the peri-infarct region initiates coordinated myocardial activation some distance from the stimulus site with substantial associated time delays. This is site dependent and heterogeneous and occurs for <50% of ectopic stimuli in the border zone. Furthermore, once coordinated activation is initiated, conduction velocity adjacent to the infarct boundary is not significantly different from control. These results give new insights to peri-infarct electrical activity and do not support the widespread view of uniform electrical remodeling in the border zone of chronic myocardial infarcts, with depressed conduction velocity throughout.
dc.format.medium Print-Electronic
dc.language eng
dc.publisher American Physiological Society
dc.relation.ispartofseries American journal of physiology. Heart and circulatory physiology
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm
dc.subject Myocardium
dc.subject Heart Conduction System
dc.subject Animals
dc.subject Sheep, Domestic
dc.subject Myocardial Reperfusion Injury
dc.subject Myocardial Infarction
dc.subject Disease Models, Animal
dc.subject Electrophysiologic Techniques, Cardiac
dc.subject Cardiac Pacing, Artificial
dc.subject Predictive Value of Tests
dc.subject Action Potentials
dc.subject Time Factors
dc.subject Female
dc.subject border zone
dc.subject conduction
dc.subject intramural mapping
dc.subject myocardial infarction
dc.subject Action Potentials
dc.subject Animals
dc.subject Cardiac Pacing, Artificial
dc.subject Disease Models, Animal
dc.subject Electrophysiologic Techniques, Cardiac
dc.subject Female
dc.subject Heart Conduction System
dc.subject Myocardial Infarction
dc.subject Myocardial Reperfusion Injury
dc.subject Myocardium
dc.subject Predictive Value of Tests
dc.subject Sheep, Domestic
dc.subject Time Factors
dc.subject Science & Technology
dc.subject Life Sciences & Biomedicine
dc.subject Cardiac & Cardiovascular Systems
dc.subject Physiology
dc.subject Peripheral Vascular Disease
dc.subject Cardiovascular System & Cardiology
dc.subject border zone
dc.subject conduction
dc.subject intramural mapping
dc.subject myocardial infarction
dc.subject EPICARDIAL BORDER ZONE
dc.subject REENTRANT VENTRICULAR-TACHYCARDIA
dc.subject ISCHEMIC-HEART-DISEASE
dc.subject MAGNETIC-RESONANCE
dc.subject MYOCARDIAL-INFARCTION
dc.subject RISK STRATIFICATION
dc.subject MECHANISMS
dc.subject SUBSTRATE
dc.subject SCAR
dc.subject RECONSTRUCTION
dc.subject 1102 Cardiorespiratory Medicine and Haematology
dc.subject Clinical Medicine and Science
dc.subject Cardiovascular
dc.subject Heart Disease
dc.subject Heart Disease - Coronary Heart Disease
dc.subject Cardiovascular
dc.subject 0606 Physiology
dc.subject 1116 Medical Physiology
dc.title Cardiac intramural electrical mapping reveals focal delays but no conduction velocity slowing in the peri-infarct region.
dc.type Journal Article
dc.identifier.doi 10.1152/ajpheart.00154.2019
pubs.issue 4
pubs.begin-page H743
pubs.volume 317
dc.date.updated 2021-07-27T03:01:55Z
dc.rights.holder Copyright: 2019 American Physiological Society. en
pubs.author-url https://www.ncbi.nlm.nih.gov/pubmed/31419152
pubs.end-page H753
pubs.publication-status Published
dc.rights.accessrights http://purl.org/eprint/accessRights/RetrictedAccess en
pubs.subtype Research Support, Non-U.S. Gov't
pubs.subtype Journal Article
pubs.elements-id 784221
dc.identifier.eissn 1522-1539


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