The effect of increased coronary flow on transmural ventricular repolarization was investigated in 6 pentobabital-anaesthetised sheep. The left circumflex coronary artery (LCX) was injected with fresh blood at 10 ml/min 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 as an estimate of 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 msec, respectively (p<0.01). Pre-treatment 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 transmural ventricular repolarization duration. These effects appear to be mediated by nitric oxide from the coronary endothelium.
|Number of pages||6|
|Publication status||Published - 2007|