This document discusses the link between the ex vivo storage interval of vein grafts and subsequent graft failure after coronary artery bypass grafting (CABG). It notes that veins and arteries used as grafts can be considered transplant organs that are subject to damage during harvesting and storage prior to grafting. Studies have found that buffered preservation solutions may better protect grafts during storage compared to saline or blood, with one trial finding a 70% reduced risk of graft failure when using buffered solutions. The document argues that grafts should be viewed similarly to transplanted organs in order to reduce storage-related damage that can lead to asymptomatic graft failure over time.

1. The Link between Ex Vivo
Storage Interval and Subsequent
Failure of Vein Grafts
Robert Poston, MD
Chairman, Department of Cardiothoracic Surgery
St Francis Medical Center, Trenton, NJ

2. Choice of
conduit
• Arterial vs. venous: OR 10
Harvesting
conduit
• “No touch” vs. conventional: OR 3.1
• Open vs. endoscopic: OR 2
Storage of
conduit
Anastomotic
technique
• Interrupted vs. continuous: OR 1.4
• On-pump vs. off-pump: OR 1.3
Postoperative
management
• Aggressive vs. standard statin therapy: OR 1.3
• Aspirin vs. no aspirin: OR 2.2
Factors that influence
graft patency post-CABG
?

3. Mechanism of early graft failure
Endothelial dysfunction
Arterial conduits
Meticulous harvest
Statin therapy
Hypercoagulability
Anti-platelet therapy
Abnormal flow
Perfect anastomotic
technique
THROMBOSIS

4. Status of bypass graft endothelium
In situ
(baseline)
Ex vivo storage
(after explant)
After
grafting onto
the heart
?
Normal endothelium Disrupted endothelium

5. Recovery of venous endothelium after grafting
• Large animal studies
• Venous vs. prosthetic grafts

6. HANDLE WITH CARE

7. The Vascular Conduit as a Transplant Organ
• Veins/arteries are organs:
• differentiated structures comprised of two or more tissues working together to provide a specific
function
• Respond to a variety of complex signals including hormones, other molecules and nerve impulses to
adjust blood flow
• Correct functioning is dependent upon proper integrated functioning of vessel’s constituent tissues
• Majority of vascular grafts are transplanted autologous vein or artery derived grafts-
• Vascular grafts and heterologous organ transplants are subject to many of the same
graft failure mechanisms:
• Oxidative damage
• Storage lesions
• Ischemia Reperfusion Injury

8. Subanalysis of preservation solutions from the
PREVENT IV Trial1
• Multicenter, randomized, placebo-controlled trial of edifoligide during
CABG
• Enrolled 3014 patients at 107 US sites from 8/1/02 – 10/22/03
• Analyzed the impact of preservation solution on graft patency
Saline
Blood
Buffered
saline
1. Harskamp et al. JAMA Surg. 2014;149(8):798-805

10. Choice of
conduit
• Arterial vs. venous: OR 10
Harvesting
conduit
• “No touch” vs. conventional: OR 3.1
• Open vs. endoscopic: OR 2
Storage of
conduit
Anastomotic
technique
• Interrupted vs. continuous: OR 1.4
• On-pump vs. off-pump: OR 1.3
Postoperative
management
• Aggressive vs. standard statin therapy: OR 1.3
• Aspirin vs. no aspirin: OR 2.2
Factors that influence
graft patency post-CABG
Buffered solution vs. other
alternatives: OR 1.7

11. Ischemic damage
is “invisible”
• Bypass graft failure often asymptomatic
• Whole organ failure never asymptomatic
Saline/blood
standard of care
• Informational cascade
Saline/blood used
when training
• Reputational cascade
Selective
emphasis of risk
factors
• Easy to see the influence of technical/anatomic factors
• Difficult to see the analogy to organ transplant
Factors that influenced
choice of vein solution