Document Detail

Effects of tilt and exercise on signal-averaged electrocardiogram after acute myocardial infarction.
MedLine Citation:
PMID:  2354703     Owner:  NLM     Status:  MEDLINE    
To determine whether enhanced sympathetic activity could alter a non-invasive index of cardiac instability, we analysed the effects of 90 degrees head-up tilt and submaximal exercise stress test on high amplification signal-averaged electrocardiogram in 64 patients after acute myocardial infarction. At rest, ventricular late potentials were detected in 25% of patients, characterized by a significant prolongation of filtered QRS complex (137 +/- 3 vs 115 +/- 2 ms) and of its components smaller than 40 microV (38 +/- 2 vs 16 +/- 1 ms), as well as by a reduced root mean square voltage calculated for the terminal 40 ms of QRS complex (RMS40 voltage) (19 +/- 1 vs 75 +/- 9 microV) in comparison to patients without micropotentials. Sympathetic activation induced by tilt caused a significant increase in heart rate (from 67 +/- 3 to 79 +/- 3 beats min-1) but did not modify either the incidence of ventricular late potentials or the values of any of the signal-averaged electrocardiogram parameters considered. In 19 patients, recordings were also obtained during a submaximal bicycle exercise stress test at a heart rate of 114 +/- 4 beats min-1 and with systolic arterial blood pressure at 153 +/- 6 mmHg. No effect on signal-averaged electrocardiogram parameters was detectable during this experimental intervention. These data indicate that after myocardial infarction, sympathetic activation does not seem to modify signal-averaged electrocardiogram parameters.
F Lombardi; M L Finocchiaro; L Dalla Vecchia; R Sala; M Garimoldi; G Baselli; S Cerutti; A Malliani
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  European heart journal     Volume:  11     ISSN:  0195-668X     ISO Abbreviation:  Eur. Heart J.     Publication Date:  1990 May 
Date Detail:
Created Date:  1990-07-20     Completed Date:  1990-07-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8006263     Medline TA:  Eur Heart J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  421-8     Citation Subset:  IM; S    
Patologia Medica, Centro Fidia, Cardiologia, Ospedale L. Sacco, Milano, Italy.
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MeSH Terms
Exercise / physiology*
Heart Conduction System / physiopathology
Middle Aged
Myocardial Infarction / diagnosis*,  physiopathology
Posture / physiology*
Signal Processing, Computer-Assisted*
Sympathetic Nervous System / physiopathology

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