Effects of selectively altering collateral driving pressure on regional perfusion and function in occluded coronary bed in the dog.

To determine whether selectively altering the coronary perfusion pressure in the adjacent nonoccluded vessel has any influence on the occluded bed, the effects of alterations in the perfusion pressure of the left anterior descending coronary artery on the perfusion and function of the acutely occluded left circumflex coronary (LC) arterial bed were studied in 10 anesthetized open-chest dogs. Radiolabelled microsphere-assessed regional myocardial perfusion and endocardial excursion determined by two-dimensional echocardiography were measured during control conditions prior to mid-LC occlusion with left anterior descending coronary arterial pressure (LADP) equal to aortic pressure (AoP) (Stage 0) and to 3 randomly performed postocclusion stages. At each postocclusion stage, the perfusion territory of the occluded LC bed (area at risk) was measured in vivo using myocardial contrast two-dimensional echocardiography. During Stage 1 (LADP = AoP), area at risk was 5.1 +/- 0.9 cm2 (x +/- 1 SD) and transmural blood flow to the LC arterial bed decreased from 0.96 +/- 0.50 ml/min/g (Stage 0) to 0.16 +/- 0.12 ml/min/g (p less than 0.01), while endocardial excursion decreased from 28.0 +/- 9.0% to 2.0 +/- 10.0% (p less than 0.01). During Stage 2 (LADP greater than AoP), area at risk decreased to 4.4 +/- 1.0 cm2 compared with Stage 1 (p less than 0.01), and transmural blood flow, endocardial:epicardial blood flow ratio, and endocardial excursion increased to 0.51 +/- 0.39 ml/min/g, 0.64 +/- 0.20, and 14 +/- 6%, respectively (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)