• Amplifying the severity of all three risk factors of Virchow's triad is expected to lead to a synergistic increase in regional thrombin formation [ Time Frame: Measured at 5 years ] [ Designated as safety issue: Yes ]
  
• Pressure distention is the main stimulus that creates a loss of thrombin control within the SVG [ Time Frame: Measured at 5 years ] [ Designated as safety issue: Yes ]
  
• Accurate tests of graft quality will be developed that provide rapid results for ready translation into clinical applications [ Time Frame: Measured at 5 years ] [ Designated as safety issue: Yes ]
  
• Aprotinin or bivalirudin will effectively suppress thrombin generation and its effects within the highest risk grafts [ Time Frame: Measured at 5 years ] [ Designated as safety issue: No ]
  

The saphenous vein, which runs from the ankle to the groin along the inside of the leg, is commonly used as a graft for people undergoing a CABG surgery. The vein is removed from the leg and reattached to the heart to create a detour around the blocked part of a coronary artery. Following this procedure, many people are prescribed aspirin as a way to increase the chance that the graft procedure will be successful. However, saphenous vein graft failure may still occur in some people, indicating a need to understand why this happens and who might be at risk for graft failure. Thrombin, a protein involved in the blood clotting process, is somehow related to aspirin resistance, abnormalities in blood flow, and cell disruption within the saphenous vein, all factors thought to increase the risk of graft failure. The purpose of this study is to evaluate the likelihood that a burst in thrombin contributes to graft failure in people who have recently undergone a CABG procedure using the saphenous vein.

This study will enroll individuals undergoing CABG surgery at the University of Maryland. Prior to and immediately following surgery, an incision will be made in the skin and the time required for the blood to form a clot will be determined. During surgery, participants' blood vessels will be examined using imaging and cell analysis techniques. Blood collection will occur before surgery, immediately after surgery, and on Days 1, 3, and 30 following surgery. A portion of blood will be frozen for future analysis. An x-ray of the saphenous vein will be performed on Day 5 and again at a follow-up visit 6 to 12 months following surgery. Kidney function will be measured at both of these visits prior to the x-ray procedure. At the second visit, health and mental status questionnaires will be completed.

Male and female patients between the the age of 18-90 years belonging to all races will be enrolled in the study

Inclusion Criteria:

• Scheduled for CABG surgery at University of Maryland Medical System (UMMS)
• For females, willing to use a reliable form of birth control for the duration of the study

Exclusion Criteria:

• Non-dermatologic allergy to intravenous (IV) radiographic contrast
• Creatinine levels greater than 2.0 mg/dL
• Pregnant