Abstract
Background End-to-side (ETS) anastomoses are necessary for many procedures in microvascular
surgery, such as free flap transfers. In training courses that use the rat model,
the arterial end to venous side (AEVS) anastomosis is a common training exercise for
ETS anastomoses. Surgeons-in-training often inadvertently twist the artery when completing
the AEVS anastomosis; however, in the clinical setting, torsion is a reported risk
factor for ETS anastomosis failure. The purpose of this study was to determine if
torsion in an AEVS anastomosis would have a negative effect on patency in the rat
model, accurately simulating the clinical scenario.
Methods All AEVS anastomoses were completed in 15 Sprague–Dawley rats divided into three
torsion cohorts: 0, 90, and 180 degrees. Torsion was created in the AEVS anastomosis
by mismatching the first two sutures placed between the free femoral artery end and
the venotomy. Patency was verified at 0, 2, and 4 hours postoperation via the oxygenated–deoxygenated
test and transit-time ultrasound blood flow measurements.
Results All AEVS anastomoses were patent 0, 2, and 4 hours postoperation according to both
the oxygenated–deoxygenated test and transit-time ultrasound blood flow measurements.
For the average blood flow measurements at 4 hours postoperation, the proximal measurements
for 0, 90, and 180 degrees were −34.3, −18.7, and −13.8 mL/min respectively, and the
distal measurements were 4.48, 3.46, and 2.90 mL/min, respectively.
Conclusion Torsion of 180 degrees does not affect early AEVS anastomosis patency in the rat
model. This contrasts with the clinical setting, where torsion is reported to cause
ETS anastomosis failure. Since AEVS anastomosis torsion is often difficult to appreciate
visually, we suggested that microvascular surgery training instructors include a method
to both detect and prevent AEVS anastomosis torsion, such as by marking the free femoral
artery end with a marking pen or suture before beginning the anastomosis.
Keywords
torsion - end-to-side anastomosis - arteriovenous fistula
