Details of coronary stenosis morphology influence its hemodynamic severity and distal flow reserve

Differences in coronary flow reserve with anatomically similar coronary artery stenoses have been attributed to 1) nonstandard physiologic conditions, 2) inadequacies of measurements of coronary artery stenosis dimension and/or coronary blood flow, and 3) inadequate hyperemic stimulus. Our study tested the hypothesis that details of coronary artery stenosis geometry, which may or may not be apparent on coronary angiograms, also may contribute importantly to such differences. A simple and complex coronary artery stenosis, each of which reduced vessel cross-sectional area by 84%, was introduced in random order into the left anterior descending coronary artery of nine closed-chest, sedated swine. The simple stenosis had a single lumen while the complex stenosis had five small lumena whose combined area equaled that of the single lumen stenosis. Measurements of hemodynamics and regional myocardial blood flow (microspheres) were made at control and after 10 minutes of adenosine infused at 400 micrograms/min and then at 800 micrograms/min distal to each stenosis. Both heart rate and aortic mean pressure were controlled and thus did not change versus initial baseline (129 +/- 4 minutes and 120 +/- 10 mm Hg, mean +/- SD, respectively) during the study. Baseline total flow (ml/sec) distal to the stenosis was similar at each control (1.05 +/- 0.35 vs. 0.92 +/- 0.34, simple versus complex, respectively; p = NS). At maximal adenosine, total flow with the simple stenosis was 3.44 +/- 0.92 versus 2.77 +/- 0.51 for complex (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)