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Improvement in forward coronary blood flow by using a reversed saphenous vein with a competent valve
Insights
Reversed saphenous veins with a competent valve significantly increase blood flow in aortocoronary bypass (ACB) surgery. This valve-containing graft may be the preferred choice for coronary artery revascularization.
Area of Science:
- Cardiovascular Surgery
- Vascular Grafts
- Hemodynamics
Background:
- Reversed saphenous veins are standard for aortocoronary bypass (ACB).
- Alternative grafts like internal mammary arteries show higher patency but lower flow.
- Retrograde flow during cardiac systole can impede forward coronary blood flow.
Purpose of the Study:
- To evaluate the impact of a competent valve within reversed saphenous vein grafts on coronary artery blood flow.
- To determine if preventing retrograde flow improves graft performance.
Main Methods:
- Thirty-nine reversed saphenous vein grafts with competent valves were implanted in 32 patients undergoing ACB.
- Mean and pulsatile blood flow were measured distal to the valve in both competent and incompetent states.
- Flow measurements were analyzed for grafts in the right and left coronary arteries.
Main Results:
- A competent valve in right coronary artery grafts increased mean flow by 29.7% and pulsatile flow by 17.7%.
- A competent valve in left coronary artery grafts increased mean flow by 31.3% and pulsatile flow by 13.7%.
- These increases in blood flow were statistically significant (p < 0.005).
Conclusions:
- A competent valve in reversed saphenous vein grafts enhances coronary artery blood flow compared to valveless grafts.
- This type of valved graft may represent an improved conduit for coronary artery revascularization.
Abstract:
Reversed segments of saphenous vein have been the grafts of choice for aortocoronary bypass (ACB). Internal mammary arteries and free radial autografts have recently been shown to have a higher ppatency rate, but flow is usually lower. Normally forward coronary blood flow ceases and retrograde flow occurs during cardiac systole. Prevention of retrograde flow with a rapidly acting valve proximal to the coronary artery anastomosis should improve forward coronary blood flow. Thirty-nine reversed saphenous veins containing a competent valve were implanted in 32 patients undergoing ACB. After accurate zero flow was determined and a resting state achieved, mean (22 veins) and pulsatile (17 veins) flows were measured distal to the valve with the valve competent and temporarily incompetent. A competent valve in 10 right coronary artery vein grafts increased mean flow by 29.7% (+41 ml/min; p less than 0.005) and pulsatile flow in 6 veins by 17.7% (p less than 0.001). A competent valve in 12 left coronary artery vein grafts increased mean flow by 31.3% (+34 ml/min; p less than 0.01) and pulsatile flow in 11 veins by 13.7% (p less than 0.001). This study suggests that a portion of reversed saphenous vein containing a competent valve provides greater coronary artery blood flow than veins without valves and may be the conduit of choice for coronary artery revascularization.