We have located links that may give you full text access.
JOURNAL ARTICLE
RESEARCH SUPPORT, N.I.H., EXTRAMURAL
RESEARCH SUPPORT, NON-U.S. GOV'T
Mechanisms underlying the development of the electrocardiographic and arrhythmic manifestations of early repolarization syndrome.
Journal of Molecular and Cellular Cardiology 2014 March
Early repolarization pattern in the ECG has been associated with increased risk for ventricular tachycardia/fibrillation (VT/VF), particularly when manifest in inferior leads. This study examines the mechanisms underlying VT/VF in early repolarization syndrome (ERS). Transmembrane action potentials (APs) were simultaneously recorded from 2 epicardial sites and 1 endocardial site of coronary-perfused canine left-ventricular (LV) wedge preparations, together with a pseudo-ECG. Transient outward current (Ito) was recorded from epicardial myocytes isolated from the inferior and lateral LV of the same heart. J wave area (pseudo-ECG), epicardial AP notch magnitude and index were larger in inferior vs. lateral wall preparations at baseline and after exposure to provocative agents (NS5806+verapamil+acetylcholine (ACh)). Ito density was greater in myocytes from inferior vs. lateral wall (18.4 ± 2.3pA/pF vs. 11.6 ± 2.0pA/pF; p<0.05). A combination of NS5806 (7 μM) and verapamil (3 μM) or pinacidil (4 μM), used to pharmacologically model the genetic defects responsible for ERS, resulted in prominent J-point and ST-segment elevation. ACh (3 μM), simulating increased vagal tone, precipitated phase-2-reentry-induced polymorphic VT/VF. Using identical protocols, inducibility of arrhythmias was 3-fold higher in inferior vs. lateral wedges. Quinidine (10 μM) or isoproterenol (1 μM) restored homogeneity and suppressed VT/VF. Our data support the hypothesis that 1) ERS is caused by a preferential accentuation of the AP notch in the LV epicardium; 2) this repolarization defect is accentuated by elevated vagal tone; 3) higher intrinsic levels of Ito account for the greater sensitivity of the inferior LV wall to development of VT/VF; and 4) quinidine and isoproterenol exert ameliorative effects by reversing the repolarization abnormality.
Full text links
Related Resources
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app