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Effects of cardioplegic solutions and their components on human saphenous vein contractility
M Chiavarelli1, F Fabi, T Stati
1Department of Cardiovascular Surgery, University of Rome, La Sapienza, Italy.
Insights
Cardioplegic solutions can damage vein grafts, leading to thrombosis. Avoiding solutions that constrict veins may improve coronary artery bypass graft patency.
Area of Science:
- Cardiovascular Surgery
- Vascular Biology
- Biochemistry
Background:
- Cardioplegic solution administration via vein grafts is standard practice.
- Endothelial damage from cardioplegia may cause graft thrombosis.
- The impact of cardioplegic solutions on saphenous vein contractility is not fully understood.
Purpose of the Study:
- To compare the effects of different cardioplegic solutions and their components on human saphenous vein contractility.
- To identify solution compositions that may contribute to graft thrombosis.
- To inform the development of cardioplegic solutions that enhance graft patency.
Main Methods:
- In vitro analysis of human saphenous vein segments.
- Exposure to three distinct cardioplegic solutions with varying potassium (K+), sodium (Na+), magnesium (Mg2+), and lidocaine concentrations.
- Assessment of venoconstriction and vasodilatation responses.
Main Results:
- A solution high in K+ (30 mmol/L) and low in Na+ (82 mmol/L) caused significant venoconstriction.
- Lowering K+ to 10 mmol/L and increasing Na+ to 92 mmol/L reduced vasoconstriction.
- A solution with 16 mmol/L K+, 16 mmol/L Mg2+, and lidocaine induced vasodilatation.
- High K+, low Na+, and lidocaine caused dose-dependent vasoconstriction; high Mg2+ caused vasodilatation.
Conclusions:
- Cardioplegic solution composition significantly impacts saphenous vein vasomotor tone.
- Venoconstrictive solutions may compromise endothelial integrity and graft patency.
- Avoiding venoconstrictor infusates is recommended to improve coronary artery bypass graft outcomes.
Abstract:
Cardioplegic solution administration into the vein graft is an established method to ensure cardioplegic distribution beyond coronary artery stenoses. The ultrastructural demonstration of severe endothelial damage after cardioplegic exposure suggests that intravenous cardioplegic administration can contribute to early and late graft thrombosis. The direct effect on human saphenous vein contractility of three cardioplegic solutions and their components was compared. A solution with 30 mmol/L K+ and 82 mmol/L Na+ produced intense venoconstriction. Lowering the potassium level to 10 mmol/L and increasing the sodium level to 92 mmol/L reduced its vasoconstricting action. A third solution with 16 mmol/L K+, 16 mmol/L Mg2+, and lidocaine caused venodilatation. Analysis of the single component effects showed that high potassium level, low sodium level, and the addition of lidocaine produced concentration-dependent vasoconstriction. High magnesium concentration resulted in vasodilatation. The present data suggest that cardioplegic solution composition may cause marked vasomotor effects on saphenous vein and thus influence its endothelial integrity. In the search for an "ideal solution" to the cardioplegic controversy, a venoconstrictor infusate should be avoided to improve patency rates of coronary artery bypass grafts.