[en] AIMS: The time constant of left ventricular (LV) relaxation derived from a monoexponential model is widely used as an index of LV relaxation rate, although this model does not reflect the non-uniformity of ventricular relaxation. This study investigates whether the relaxation curve can be better fitted with a "quadratic" model than with the "conventional" monoexponential model and if changes in the LV relaxation waveform due to acute myocardial ischemia could be better detected with the quadratic model. METHODS AND RESULTS: Isovolumic relaxation was assessed with quadratic and conventional models during acute myocardial ischemia performed in 6 anesthetized pigs. Mathematical development indicates that one parameter (Tq) of the quadratic model reflects the rate of LV relaxation, while the second parameter (K) modifies the shape of the relaxation curve. Analysis of experimental data obtained in anesthetized pigs showed that the shape of LV relaxation consistently deviates from the conventional monoexponential decay. During the early phase of acute myocardial ischemia, the rate and non-uniformity of LV relaxation, assessed with the quadratic function, were significantly enhanced. Tq increased by 16% (p<0.001) and K increased by 12% (p<0.001) within 30 and 60min, respectively, after left anterior descending (LAD) coronary artery occlusion. However, no significant changes were observed with the conventional monoexponential decay within 60min of ischemia. CONCLUSIONS: The quadratic model better fits LV isovolumic relaxation than the monoexponential model and can detect early changes in relaxation due to acute myocardial ischemia that are not detectable with conventional methods.
Disciplines :
Engineering, computing & technology: Multidisciplinary, general & others Cardiovascular & respiratory systems
Author, co-author :
MORIMONT, Philippe ; Centre Hospitalier Universitaire de Liège - CHU > Frais communs médecine
Pironet, Antoine ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Thermodynamique des phénomènes irréversibles
Desaive, Thomas ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Thermodynamique des phénomènes irréversibles
Chase, Geoffrey
LAMBERMONT, Bernard ; Centre Hospitalier Universitaire de Liège - CHU > Frais communs médecine
Language :
English
Title :
Early detection of abnormal left ventricular relaxation in acute myocardial ischemia with a quadratic model.
Publication date :
2014
Journal title :
Medical Engineering and Physics
ISSN :
1350-4533
eISSN :
1873-4030
Publisher :
Elsevier, Oxford, United Kingdom
Volume :
36
Issue :
9
Pages :
1101-1105
Peer reviewed :
Peer Reviewed verified by ORBi
Commentary :
Copyright (c) 2014 IPEM. Published by Elsevier Ltd. All rights reserved.
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