부산대학교 도서관

Increased mechanical tension in the ischemic region during acute coronary occlusion might favor the occurrence of phase lb ventricular arrhythmias. We aimed to investigate whether intracoronary administration of Gd3+ a stretch-activated channel blocker, into the ischemic zone reduces the incidence of these arrhythmias. In thiopental-anesthetized, open-chest pigs, the left anterior descending coronary artery (LAD) was ligated for 45 or 48 mm. Phosphate-free, HEPES- buffered saline bubbled with 100% N2 was infused into the ischemic region for 4 mm, starting 5 mm (series A; n = 16) or 20 mm (series B; n = 16) after coronary occlusion, at a rate doubling the baseline blood flow. Animals were blindly allocated to receive 40 µM Gd3+ or only the buffer during the final 2 mm of the infusion. There were no differences between groups with respect to hemodynamic variables, plasma K+ levels, or size of the ischemic region. In neither series was the number of phase lb premature ventricular beats reduced by Gd3+ (46 ± 20 in untreated vs. 91 ± 37 in Gd3+-treated animals in series A and 19 ± 7 vs. 22 ± 13, respectively, in series B; both P = not significant). The occurrence of ventricular tachycardia or fibrillation was significantly associated with the magnitude of early ischemic expansion of the LAD region, as measured by ultrasonic crystals, but was also not prevented by Gd3+ These results argue against a major role of stretch-activated channels inside the area at risk in the genesis of phase Ib ischemic ventricular arrhythmias. [ABSTRACT FROM AUTHOR]