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Alterations of phasic coronary artery flow velocity in humans during percutaneous coronary angioplasty
1Division of Cardiology, George Washington University, Washington, D.C.
Insights
Doppler guide wire measurements of coronary artery blood flow velocity and diastolic/systolic velocity ratio distal to stenosis are more relevant than flow reserve for assessing angioplasty outcomes. These distal measurements reflect immediate physiologic changes after coronary angioplasty.
Area of Science:
- Cardiovascular medicine
- Interventional cardiology
- Diagnostic imaging
Background:
- Previous Doppler catheter studies assessing proximal coronary arteries after angioplasty showed limited success in demonstrating immediate improvement.
- Measuring blood flow velocity and reserve distal to a stenosis may offer insights into the physiologic significance of coronary artery disease.
Purpose of the Study:
- To measure blood flow velocity, flow reserve, and diastolic/systolic velocity ratio both proximal and distal to coronary artery stenosis.
- To evaluate the utility of these Doppler-derived parameters in assessing the immediate outcome of coronary angioplasty.
Main Methods:
- A low-profile Doppler angioplasty guide wire was used to obtain spectral flow velocity data.
- Measurements were performed proximal and distal to stenosis in the left anterior descending or left circumflex coronary arteries.
- The study included 38 patients undergoing angioplasty and 12 controls without significant coronary artery disease.
Main Results:
- Significant improvement in mean peak velocity was observed in distal coronary arteries post-angioplasty (19 to 35 cm/s).
- Proximal peak velocity increases were less pronounced.
- Mean flow reserve remained unchanged both proximally and distally.
- The distal diastolic/systolic velocity ratio significantly increased post-angioplasty (1.3 to 1.9), returning to normal patterns.
Conclusions:
- Doppler guide wire flow velocity measurements can be performed distal to coronary stenosis.
- Distal phasic velocity patterns and diastolic/systolic velocity ratio changes are more indicative of immediate angioplasty success than flow reserve.
- Proximal and distal flow reserve measurements immediately post-angioplasty had limited utility.
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 of 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 of 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 less than 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 greater than 0.10) and distal (1.6 +/- 1 vs. 1.5 +/- 0.8; p greater than 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 less than 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 less than 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 greater than 0.10) and did not change significantly after angioplasty (1.8 +/- 0.8 vs. 2.13 +/- 0.9; p greater than 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.