Document Detail

Evidence of unbalanced regulatory mechanism of heart rate and systolic pressure after acute myocardial infarction.
MedLine Citation:
PMID:  12181151     Owner:  NLM     Status:  MEDLINE    
The interactions between systolic arterial pressure (SAP) and R-R interval (RR) fluctuations after acute myocardial infarction (AMI) were investigated by measures of synchronization separating the feedback from the feedforward control and capturing both linear and nonlinear contributions. The causal synchronization, evaluating the ability of RR to predict SAP (chi(s/t)) or vice versa (chi(t/s)), and the global synchronization (chi) were estimated at rest and after head-up tilt in 35 post-AMI patients, 20 young and 12 old. Significance and nonlinearity of the coupling were assessed by surrogate data analysis. Tilting increased the number of young subjects in which RR-SAP link was significant (from 17 to 19) and linear (from 11 to 18). In AMI, both significance and linearity of the coupling were low at rest (26 significant and 24 nonlinear) and further reduced after tilt (17 significant and 16 nonlinear). Old subjects showed a partial recovery of linearity after tilt (rest: 1 linear of 7 significant; tilt: 5 linear of 8 significant). In young subjects, the causal synchronization indexes were balanced and increased from rest (chi(t/s) = 0.072 +/- 0.037 and chi(s/t) = 0.054 +/- 0.028) to tilt (chi(t/s) = 0.125 +/- 0.071 and chi(s/t) = 0.108 +/- 0.053). On the contrary, in old subjects and AMI patients, the feedforward was prevalent to the feedback coupling at rest (old: chi(t/s) = 0.041 +/- 0.023 and chi(s/t) = 0.069 +/- 0.042; AMI: chi(t/s) = 0.050 +/- 0.030 and chi(s/t) = 0.089 +/- 0.053). Tilting blunted the unbalance in old subjects (chi(t/s) = 0.065 +/- 0.052 and chi(s/t) = 0.069 +/- 0.044) but not in AMI patients (chi(t/s) = 0.040 +/- 0.019 and chi(s/t) = 0.060 +/- 0.040). Thus, after AMI, nonlinear mechanisms are elicited in RR-SAP interactions. Furthermore, the neural regulation of the cardiovascular system resulted in imbalance as a consequence of impaired feedback and enhanced feedforward control mechanisms.
Giandomenico Nollo; Luca Faes; Alberto Porta; Barbara Pellegrini; Flavia Ravelli; Maurizio Del Greco; Marcello Disertori; Renzo Antolini
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  283     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2002 Sep 
Date Detail:
Created Date:  2002-08-15     Completed Date:  2002-09-13     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H1200-7     Citation Subset:  IM    
Dipartimento di Fisica, Università di Trento, and Istituto Trentino di Cultura-ist, 38050 Povo, Trento, Italy.
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MeSH Terms
Autonomic Nervous System / physiology*
Baroreflex / physiology
Blood Pressure / physiology*
Feedback, Physiological / physiology
Heart Rate / physiology*
Middle Aged
Myocardial Infarction / physiopathology*

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