Effects of acute coronary occlusion on hemodynamics in an adjacent coronary artery in dogs

The effects of acute occlusion of 1 coronary artery on flow responses in another were studied in 24 open-chest dogs. Left circumflex (LC) flow was measured with and without LC stenoses before and during reactive hyperemia. In 19 dogs the left anterior descending artery (LAD) was occluded and measurements were repeated after 1 hour (group 1). Four dogs had measurements before and after 1 hour without LAD occlusion (group 2). In group 2 no systemic, left ventricular (LV) or coronary hemodynamic changes were observed after 1 hour. In group 1, an hour after LAD occlusion, heart rate and aortic pressure had not changed but stroke volume decreased slightly (-8 +/- 7%, mean +/- SD, p = not significant) and LV end-diastolic pressure had increased (2 +/- 3 mm Hg, p less than 0.05). Basal LC flow was not changed by less than 90% LC stenosis. Ninety percent LC stenosis decreased LC flow both before and after LAD occlusion. During reactive hyperemia without LC stenosis, LC flow decreased after LAD occlusion in 15 of 19 dogs (from 154 +/- 80 to 141 +/- 75 ml/min, p less than 0.05). With 60 and 80% LC stenoses, LC flow during reactive hyperemia decreased before LAD occlusion (110 +/- 62 and 74 +/- 40 ml/min, respectively), but decreased further (both p less than 0.05) after LAD occlusion (98 +/- 54 and 63 +/- 43 ml/min).(ABSTRACT TRUNCATED AT 250 WORDS)