Characterization of the nonlinear content of the heart rate dynamics during myocardial ischemia.
We develop a method to quantify the changes in heart rate dynamics during local myocardial ischemia induced by a percutaneous transluminal coronary angioplasty procedure (PTCA). The method introduces an index measuring the nonlinear content of the beat-to-beat (RR) time series by using nonlinear time series techniques such as surrogate data analysis and average mutual information. The index is applied to RR data from 67 subjects obtained before, during, and after the ischemic period and shows an increase in the nonlinearity of the cardiac control dynamics during ischemic and reperfusion stages. The nonlinear index is also used to characterize the effects of performing the coronary occlusion at different arteries and distances. We observe that the effect of ischemia becomes larger as the occlusion distance is reduced, and that most of the changes in the nonlinear content of the dynamics occur at long time scales typically related to sympathetic modulation of the cardiac rhythm (6-25 s).
Benitez
Raul
R
Automatic Control Department, Universitat Politècnica de Catalunya, C/Compte d'Urgell 187, 08036 Barcelona, Spain. raul.benitez@upc.edu
Alvarez-Lacalle
Enrique
E
Echebarria
Blas
B
Gomis
Pedro
P
Vallverdu
Montserrat
M
Caminal
Pere
P
D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D003198:Computer Simulation; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D004562:Electrocardiography / Q000379:methods*; D006305:Health Status Indicators; D006339:Heart Rate; D006801:Humans; D008955:Models, Cardiovascular; D017202:Myocardial Ischemia / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D017711:Nonlinear Dynamics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity