The Value of Vein Graft Surveillance in Bypasses Performed with Small-Diameter Vein Grafts

Validation of a Decision Tree to Streamline Infrainguinal Vein Graft Surveillance

BACKGROUND

Duplex ultrasound (DU)-based graft surveillance remains controversial. The aim of this study was to assess the ability of a recently proposed decision tree in identifying high-risk grafts which would benefit from DU-based surveillance.

MATERIALS AND METHODS

Consecutive patients undergoing infrainguinal vein graft bypass from January 2008 to December 2015 were identified from the National Vascular registry and enrolled in a duplex surveillance program. An early postoperative DU was performed at a median of 6 weeks (range: 4-9 weeks). Grafts were classified into high risk or low risk based on the findings of the earliest postoperative scan and 4 established risk factors for graft failure (diabetes, smoking, infragenicular distal anastomosis, and revision bypass surgery) using a classification and regression tree (CRT). The accuracy of the CRT model was evaluated using area under receiver operator characteristic (AROC) curve.

RESULTS

About 278 vein graft bypasses were performed; 29 grafts had occluded by the first surveillance visit; 249 vein grafts were entered into surveillance. Sixty-four (23%) developed critical stenosis. Overall 30-month primary patency, primary-assisted patency, and secondary patency rates were 71.2%, 77.2%, and 80.1%, respectively. AROC for prediction of graft stenosis or occlusion was 83% (95% confidence interval [CI]: 78-87%). The sensitivity and specificity of the CRT model for prediction of graft stenosis or occlusion were 95% (95% CI: 88-98%) and 52.2% (95% CI: 45-60%).

CONCLUSIONS

A prediction model based on commonly recorded clinical variables and early postoperative DU scan is accurate at identifying grafts which are at high risk of failure. These high-risk grafts may benefit from DU-based surveillance.

Mechanical properties of human autologous tubular connective tissues (human biotubes) obtained from patients undergoing peritoneal dialysis

Completely autologous in vivo tissue-engineered connective tissue tubes (Biotubes) have promise as arterial vascular grafts in animal implantation studies. In this clinical study of patients undergoing peritoneal dialysis (PD) (n = 11; age: 39-83 years), we evaluated human Biotubes' (h-Biotubes) mechanical properties to determine whether Biotubes with feasibility as vascular grafts could be formed in human bodies. We extracted PD catheters, embedded for 4-47 months, and obtained tubular connective tissues as h-Biotubes (internal diameter: 5 mm) from around the catheter' silicone tubular parts. h-Biotubes were composed mainly of collagen with smooth luminal surfaces. The average wall thickness was 278 ± 178 μm. No relationship was founded between the tubes' mechanical properties and patients' ages or PD catheter embedding periods statistically. However, the elastic modulus (2459 ± 970 kPa) and tensile strength (623 ± 314 g) of h-Biotubes were more than twice as great as those from animal Biotubes, formed from the same PD catheters by embedding in the beagle subcutaneous pouches for 1 month, or beagle arteries. The burst strength (6338 ± 1106 mmHg) of h-Biotubes was almost the same as that of the beagle thoracic or abdominal aorta. h-Biotubes could be formed in humans over a 4-month embedding period, and they satisfied the mechanical requirements for application as vascular grafts. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1431-1437, 2016.