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

Thrombin Dysregulation Leads to Early Saphenous Vein Graft Failure

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.

Study Overview

• Status: Unknown
• Conditions: Coronary Artery Bypass; Thrombosis

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.

• Study Type: Observational
• Enrollment (Anticipated): 450

Contacts and Locations

• Study Contact: Name: Robert S. Poston, MD; Phone Number: 520-626-7951; Email: rposton@surgery.arizona.edu

Study Locations

• United States
  • Arizona
    • Tucson, Arizona, United States, 85724
      • Recruiting
      • University of Arizona College of Medicine
      • Principal Investigator: Robert S. Poston, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 90 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

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

Description

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

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Only
• Time Perspectives: Prospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure	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

Collaborators and Investigators

• Sponsor: University of Arizona
• Collaborators: University of Maryland, Baltimore County
• Investigators: Principal Investigator: Robert S. Poston, MD, University of Arizona, Tucson

Publications and helpful links

General Publications

• Desai P, Kiani S, Thiruvanthan N, Henkin S, Kurian D, Ziu P, Brown A, Patel N, Poston R. Impact of the learning curve for endoscopic vein harvest on conduit quality and early graft patency. Ann Thorac Surg. 2011 May;91(5):1385-91; discussion 1391-2. doi: 10.1016/j.athoracsur.2011.01.079.
• Poston RS, Tran R, Collins M, Reynolds M, Connerney I, Reicher B, Zimrin D, Griffith BP, Bartlett ST. Comparison of economic and patient outcomes with minimally invasive versus traditional off-pump coronary artery bypass grafting techniques. Ann Surg. 2008 Oct;248(4):638-46. doi: 10.1097/SLA.0b013e31818a15b5.

Study record dates

Study Major Dates

• Study Start: February 1, 2007
• Primary Completion (Anticipated): May 1, 2013
• Study Completion (Anticipated): December 1, 2013

Study Registration Dates

• First Submitted: May 31, 2007
• First Submitted That Met QC Criteria: May 31, 2007
• First Posted (Estimate): June 4, 2007

Study Record Updates

• Last Update Posted (Estimate): May 10, 2013
• Last Update Submitted That Met QC Criteria: May 8, 2013
• Last Verified: May 1, 2013

More Information

Terms related to this study

• Keywords: Virchow's Triad; Thrombin; Graft Failure
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Embolism and Thrombosis; Thrombosis
• Other Study ID Numbers: 479; R01HL084080-01A1 (U.S. NIH Grant/Contract)