ALTERATIONS OF PHASIC CORONARY-ARTERY FLOW VELOCITY IN HUMANS DURING PERCUTANEOUS CORONARY ANGIOPLASTY

Background and Objectives. Studies using Doppler catheters to assess blood flow velocity and vasodilator reserve in proximal coronary arteries have failed to demonstrate significant improvement immediately after coronary angioplasty. Measurement blood flow velocity, flow reserve and phasic diastolic/systolic velocity ratio performed distal to a coronary stenosis may provide important information concerning the physiologic significance coronary artery stenosis. This study was designed to measure these blood flow velocity variables both proximal and distal to a significant coronary artery stenosis in patients undergoing coronary angioplasty. Methods. A low profile (0.018-in.) (0.046-cm) Doppler angioplasty guide wire capable of providing spectral flow velocity data was used to measure blood flow velocity, flow reserve and diastolic/systolic velocity ratio both proximal and distal to left anterior descending or left circumflex coronary artery stenosis. These measurements were made in 38 patients undergoing coronary angioplasty and in 12 patients without significant coronary artery disease. Results. Significant improvement in mean time average peak velocity was noted in distal coronary arteries after angioplasty (before 19 +/- 12 cm/s; after 35 +/- 16 cm/s; p < 0.01). Increases in proximal average peak velocity after angioplasty were less remarkable (before 34 +/- 18 cm/s; after 41 +/- 14 cm/s; p = 0.04). Mean flow reserve remained unchanged after angioplasty both proximal (1.5 +/- 0.5 vs. 1.6 +/- 1; p > 0.10) and distal (1.6 +/- 1 vs. 1.5 +/- 0.8; p > 0.10) to a coronary stenosis. Before angioplasty, mean diastolic/systolic velocity ratio measured distal to a significant stenosis was decreased compared with that In normal vessels (1.3 +/- 0.5 vs. 1.8 +/- 0.5; p < 0.01). After angioplasty, distal abnormal phasic velocity patterns generally returned to normal, with a significant increase in mean diastolic/systolic velocity ratio (1.3 +/- 0.5 vs. 1.9 +/- 0.6; p < 0.01). Phasic velocity patterns and mean diastolic/systolic velocity ratio measured proximal to a coronary stenosis were not statistically different from values in normal vessels (1.8 +/- 0.8 vs. 1.8 +/- 0.5; p > 0.10) and did not change significantly after angioplasty (1.8 +/- 0.8 vs. 2.13 +/- 0.9; p > 0.10). Conclusions. Flow velocity measurements may be performed distal to a coronary stenosis with the Doppler guide wire. Phasic velocity measurements made proximal to a coronary stenosis differed from those in the distal coronary artery. Both proximal and distal flow reserve measurements made immediately after angioplasty were of limited utility. Changes in distal flow velocity patterns and diastolic/systolic velocity ratio appeared to be more relevant than the hyperemic response in assessing the immediate physiologic outcome of coronary angioplasty.