Torsion Does Not Affect Early Vein Graft Patency in the Rat Femoral Artery Model

Abstract

Background Torsion of vein grafts is a commonly cited reason for graft failure in clinical setting. Many microsurgery training courses have incorporated vein graft procedures in their curricula, and vein graft torsion is a common technical error made by the surgeons in these courses. To improve our understanding of the clinical reproducibility of practicing vein graft procedures in microsurgery training courses, this study aims to determine if torsion can lead to early vein graft failure in nonsurvival surgery rat models. Methods Sprague-Dawley rats were divided into five cohorts with five rats per cohort for a total of 25 rats. Cohorts were labeled based on degree of vein graft torsion (0, 45, 90, 135, and 180 degrees). Torsion was created in the vein grafts at the distal arterial end by mismatching sutures placed between the proximal end of the vein graft and the distal arterial end. Vein graft patency was then verified 2 and 24 hours postoperation. Results All vein grafts were patent 2 and 24 hours postoperation. At 2 hours, the average blood flow rate measurements for 0, 45, 90, 135, and 180 degrees of torsion were 0.37 ± 0.02, 0.38 ± 0.04, 0.34 ± 0.01, 0.33 ± 0.01, and 0.29 ± 0.02 mL/min, respectively. At 24 hours, they were 0.94 ± 0.07, 1.03 ± 0.15, 1.26 ± 0.22, 1.41 ± 0.11, and 0.89 ± 0.15 mL/min, respectively. Conclusion Torsion of up to 180 degrees does not affect early vein graft patency in rat models. To improve the clinical reproducibility of practicing vein graft procedures in rat models, we suggest that microsurgery instructors assess vein graft torsion prior to clamp release, as vessel torsion does not seem to affect graft patency once the clamps are removed.

Rat Microvascular Model is Tolerant to Technical Errors

“…Past literature often reported a high patency rate of up to 100% upon applying various technical errors, given the seeming discrepancy between experimental models and clinical practice. 3 4 5 6 7 8 9 10 11…”

“…Past literature often reported a high patency rate of up to 100% upon applying various technical errors, given the seeming discrepancy between experimental models and clinical practice. [3][4][5][6][7][8][9][10][11] In a microsurgery training setting, suture anastomosis is often the domain with the steepest learning curve, leading to patency failure ultimately when first beginning the training. A competent proficiency to reach anastomosis patency may take over 10 times of attempts and practice.…”

“…1,2 In-depth analyses of technical error types, including vessel torsion, large or uneven bites, back wall sutures, and others, have been shown to have varying differential effects on vessel patency in a rat model. [3][4][5][6][7][8][9][10][11] Such clinical errors are considered unacceptable in the clinical world due to the increased risk of vessel thrombosis. [12][13][14][15][16][17] However, the rat model exhibits a high tolerance to select technical errors.…”

Torsion is Tolerated in Arterial End to Venous Side Anastomoses in the Rat Model

“…This dispersion was observed in a previous study of ours that investigated the effect of torsion on interpositional vein graft patency. 17 Another example is that in clinical AVF procedures, a venous end to arterial side anastomosis is typically performed. 9 Since veins are thinner and more fragile than arteries, they may be more susceptible to thrombosis after being twisted.…”

The Benefits of Expert Instruction in Microsurgery Courses

“…In depth analyses of several error types, including vessel torsion and large or uneven bites has found that vessels may tolerate these imperfections along the suture line. [8][9][10] Nevertheless, while rat femoral vessel anastomoses may survive imprecise suturing technique, human anastomoses may not be as tolerant of technical errors. Additionally, these mistakes were evaluated on rat femoral arteries and veins, which while similar to human vessels, have not been fully evaluated.…”