RT-51
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Predictability of postischemic
recovery in isolated rat hearts by non-linear dynamics analysis
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Giampiero Merati, Sonia
Allibardi, Vittoria Margonato, Arsenio Veicsteinas, Michele Samaja, Bruno Caru.
Universita degli Studi di Milano, Brescia, and CNR, Italy
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Abstract
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Background. Fractal dimension (FD)
analysis of beat-to-beat time intervals can predict arrhythmias recurrence in patients
being treated for life-threatening ventricular arrhythmias. The aim of this study was to
assess if FD analysis of heart rate variability can be used as predictor of postischemic
myocardial recovery in an experimental model free of the endogenous and nervous
determinants of arrhythmias.
Methods. We monitored myocardial performance [left ventricle
developed pressure x heart rate (LVDP • HR), end-diastolic pressure (EDP)] as well as
heart rate variability, by FD analysis, in two groups of Langendorff-perfused isolated rat
hearts (n = 14 per group), that underwent either low-flow ischemia (low flow, normal PO2)
or hypoxia (high flow, low PO2), followed by reflow or reoxygenation.
Results. FD remained essentially constant throughout ischemia-reflow,
but increased steadily over time (p = 0.05) during hypoxiareoxygenation. LVDP • HR
recovered 86.7 ± 2.6% (p = ns vs baseline) at the end of the reflow, but only 58.9 ±
3.98% (p < 0.001 vs baseline) at the end of reoxygenation. Correspondingly, EDP
increased to 55.1 ± 4.8 and 26.3 ± 3.0 in posthypoxic and postischemic hearts (p <
0.001). We found a significant correlation between FED during hypoxia and LVDP • HR
during hypoxia-reoxygenation (r = 0.61, p = 0.05), and between FD and LVDP • HR when
both were taken during reoxygenation (r = 0.57, p = 0.04).
Conclusions. The intrinsic source of heart rate variability is more
sensitive to low perfusion than to low O2 supply. FD may be further evaluated
as possible predictor of postischemic recovery.
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Key Words
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Heart rate variability
fractal dimension analysis, non-linear dynamics analysis, postischemic recovery,
prediction of arrhythmias, OA
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