Evaluating the Role of Thrombin in Saphenous Vein Graft Failure After Heart Bypass Surgery

Study Overview
=================
Brief Summary
-----------------
Heart bypass surgery, also known as coronary artery bypass graft (CABG) surgery, creates a detour around the blocked part of a heart artery to restore blood supply to the heart muscle. The saphenous vein, located along the inside of the leg, is commonly used to create the bypass in a CABG surgery. An abnormal increase in the blood clotting protein thrombin may cause the saphenous vein graft to close up and eventually fail. This study will evaluate the relationship between thrombin levels and saphenous vein graft failures in people undergoing a CABG procedure.

Detailed Description
-----------------
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.

Official Title
-----------------
Thrombin Dysregulation Leads to Early Saphenous Vein Graft Failure

Conditions
-----------------
Coronary Artery Bypass, Thrombosis

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Scheduled for CABG surgery at University of Arizona University Medical Center (UMC) 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

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------
What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Amplifying the severity of all three risk factors of Virchow's triad is expected to lead to a synergistic increase in regional thrombin formation |  | Measured at 5 years | 
| Pressure distention is the main stimulus that creates a loss of thrombin control within the SVG |  | Measured at 5 years | 
| Accurate tests of graft quality will be developed that provide rapid results for ready translation into clinical applications |  | Measured at 5 years | 
| Aprotinin or bivalirudin will effectively suppress thrombin generation and its effects within the highest risk grafts |  | Measured at 5 years | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Virchow's Triad, Thrombin, Graft Failure