Session P81.5

Multifractal Properties of the Heart Rate Dynamics during Acute Myocardial Ischemia

R Magrans, P Gomis*, P Caminal, G Wagner

Universitat Politecnica de Catalunya
Barcelona, Spain

The percutaneous transluminal coronary angioplasty (PTCA), used to improve circulation, has been a good model to evaluate acute myocardial ischemia. The aim of this study is to quantify the dynamics of the autonomic control of the cardiac rhythm during ischemic events provoked by long PTCA procedures through indices extracted from multifractal analysis. Fifty-five patients from Staff3 database (Durham, NC) without previous myocardial infarction and artery occlusion duration of at least 3 minutes were considered. Patients were classified according to the occluded coronary artery and the position of the balloon with respect to the aorta. HRV analysis was performed using four 3 minutes-epochs: (i) pre-inflation (pre-PTCA); (ii) the first PTCA minutes (PTCA1); (iii) last PTCA minutes (PTCA2); and (iv) post deflation (post-PTCA). Two set of R-R control signals obtained 24 hours before (pre24) and after (post24) of the PTCA procedure are also available. The singularity spectrum f(alpha) was obtained using the multifractal detrended fluctuation analysis (MF-DFA) method. Then, we extracted the width of f(alpha), d-alpha, and the value alpha_m for which f(alpha) is maximum. The indices (d-alpha/alpha_m) revealed significant augment (p <0.05) during transient ischemia and reperfusion periods, indicating an increase in the multifractality of short-term HRV and a decrease of the long-range dependence on heartbeat fluctuations, which may represent a beneficial adaptive mechanism for increasing coronary flow. The differences were more notable in patients with RCA-PROX occlusions (from 0.43 to 0.68, p <0.001/from 1.15 to 1.44, p <0.001 for RCA occlusions; whereas from 0.47 to 0.66, p <0.001/from 1.24 to 1.43, p = 0.001 for PROX occlusions), which may be related to different responses of the autonomous nervous system according to the site of the ischemia. Results for pre24 (0.49/1.14) and post24 (0.46/1.13) periods show that R-R signal only change during transient myocardial ischemia and reperfusion period (p = 0.781/p = 0.131 comparing pre-PTCA vs. pre24), returning to the initial conditions 24 hours after PTCA. The multifractal indices may be a promising non-linear technique to assess the dynamics of autonomic control of the heart in presence of ischemia.

(Abstract Control Number: 171)