The effect of increased coronary flow on transmural ventricular repolarization was investigated in six pentobabital-anesthetized sheep. Fresh blood at 10 ml/min was injected into the left circumflex coronary artery (LCX) in addition to the normal coronary flow. Unipolar electrocardiograms were simultaneously registered from epicardium, mid-myocardium and endocardium with fine plunge needles. Activation-recovery interval (ARI) was measured from the unipolar electrocardiograms and was used for estimating the ventricular repolarization duration. It was found that intracoronary blood injection (n=3) prolonged ARI in the epicardium, mid-myocardium and endocardium by an average of 34 ± 16, 28 ± 18 and 25 ± 13 ms, respectively (p<0.01). Pretreatment with nitro-L-arginine (n=3), a nitric synthase inhibitor, diminished the flow-induced ARI prolongation across the ventricular wall. In conclusion, an increase in coronary flow lengthens the duration of transmural ventricular repolarization. These effects appear to be mediated by nitric oxide from the coronary endothelium., Y.-Z. Zhang, B. He, L.-X. Wang., and Obsahuje bibliografii a bibliografické odkazy
Cardiac repolarization is prolonged in diabetes mellitus (DM), however the distribution of repolarization durations in diabetic hearts is unknown. We estimated the ventricular repolarization pattern and its relation to the ECG phenomena in diabetic mice. Potential mapping was performed on the anterior ventricular surface in healthy (n=18) and alloxan-induced diabetic (n=12) mice with the 64-electrode array. Activation times, end of repolarization times, and activation-recovery intervals (ARIs) were recorded along with limb lead ECGs. ARIs were shorter in the left as compared to right ventricular leads (P<0.05). The global dispersion of repolarization, interventricular and apicobasal repolarization gradients were greater in DM than in healthy animals (P<0.03). The increased dispersion of repolarization and apicobasal repolarization gradient in DM correlated with the prolonged QTc and Tpeak-Tend intervals, respectively. The increased ventricular repolarization heterogeneity corresponded to the electrocardiographic markers was demonstrated in DM., M. A. Vaykshnorayte, A. O. Ovechkin, J. E. Azarov., and Obsahuje seznam literatury