Pedicular Arteriovenous Fistula (PAVF): Intraoperative Hemodynamic Characterization in Fasciocutaneous Free Flaps

BACKGROUND: The pedicular arteriovenous fistula (PAVF) was introduced as a technique to manipulate free flap hemodynamics through the creation of an arteriovenous shunt within the pedicle. The goal of this study was to characterize the hemodynamic effects of PAVF creation in perforator free flaps by analyzing changes in flow and resistance. METHODS: A retrospective review of patients who underwent free tissue transfer at a single institution was conducted. Fasciocutaneous flaps incorporating a PAVF were selected for this study. Intraoperative transit-time data were collected to measure volumetric flow and pulsatility index (PI). PI was used as a surrogate for vascular resistance. Transit-time measurements were obtained with the PAVF open and closed. RESULTS: Twenty-one patients (23 flaps) underwent reconstruction with perforator free flaps including a PAVF. Opening the PAVF increased mean pedicle flow from 5.9 to 22.4 mL/min (P<0.001) and estimated flap flow from 6.2 to 10.4 mL/min (P<0.001). Meanwhile, pedicle PI fell from 6.0 to 2.0 (P=0.003) with the PAVF. Larger PAVF caliber was associated with higher flow and lower PI. Only two flaps did not show flow augmentation with the PAVF, with one demonstrating possible steal. DISCUSSION: PAVF creation was associated with significant increases in pedicle flow and estimated flap flow as well as reductions in pedicle PI. This finding is consistent with more favorable hemodynamics. Larger fistulas were associated with greater hemodynamic benefits without clear evidence of vascular steal. Our data suggest that a PAVF represents a physiologically sound and reversible method to enhance free flap hemodynamics. This technique warrants further investigation.