Document Detail

Steeper restitution slopes across right ventricular endocardium in patients with cardiomyopathy at high risk of ventricular arrhythmias.
MedLine Citation:
PMID:  17098829     Owner:  NLM     Status:  MEDLINE    
Steep action potential duration (APD) restitution slopes (>1) and spatial APD restitution heterogeneity provide the substrate for ventricular fibrillation in computational models and experimental studies. Their relationship to ventricular arrhythmia vulnerability in human cardiomyopathy has not been defined. Patients with cardiomyopathy [left ventricular (LV) ejection fraction <40%] and no history of ventricular arrhythmias underwent risk stratification with programmed electrical stimulation or T wave alternans (TWA). Low-risk patients (n = 10) had no inducible ventricular tachycardia (VT) or negative TWA, while high-risk patients (n = 8) had inducible VT or positive TWA. Activation recovery interval (ARI) restitution slopes were measured simultaneously from 10 right ventricular (RV) endocardial sites during an S1-S2 pacing protocol. ARI restitution slope heterogeneity was defined as the coefficient of variation of slopes. Mean ARI restitution slope was significantly steeper in the high-risk group compared with the low-risk group [1.16 (SD 0.31) vs. 0.59 (SD 0.19), P = 0.0002]. The proportion of endocardial recording sites with a slope >1 was significantly larger in the high-risk patients [47% (SD 35) vs. 13% (SD 21), P = 0.022]. Spatial heterogeneity of ARI restitution slopes was similar between the two groups [29% (SD 16) vs. 39% (SD 34), P = 0.48]. There was an inverse linear relationship between the ARI restitution slope and the minimum diastolic interval (P < 0.001). In cardiomyopathic patients at high risk of ventricular arrhythmias, ARI restitution slopes along the RV endocardium are steeper, but restitution slope heterogeneity is similar compared with those at low risk. Steeper ARI restitution slopes may increase the propensity for ventricular arrhythmias in patients with impaired left ventricular function.
Raja J Selvaraj; Peter Picton; Kumaraswamy Nanthakumar; Vijay S Chauhan
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-11-10
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  292     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2007 Mar 
Date Detail:
Created Date:  2007-03-06     Completed Date:  2007-04-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H1262-8     Citation Subset:  IM    
Division of Cardiology, University Health Network and Mount Sinai Hospital, Toronto, Ontario, Canada.
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MeSH Terms
Cardiomyopathies / physiopathology*
Electrophysiology / methods
Middle Aged
Patient Selection
Risk Factors
Ventricular Dysfunction, Right / physiopathology*
Ventricular Fibrillation / epidemiology,  physiopathology*
Ventricular Function, Right / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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