Abstract No. 506 Neoteric Porcine Model of Arteriovenous Fistula Stenosis Treated with Percutaneous Transluminal Angioplasty

To create a clinically relevant porcine model for percutaneous transluminal angioplasty (PTA) of de novo venous stenosis (VS) in an arteriovenous fistula (AVF) and to characterize the model. Twelve castrated male Yorkshire pigs (age 4-5 months, weight 40-45 kg; Manthei Farm, Elk River, MN) were obtained to induce chronic kidney disease (CKD) through renal artery embolization of the entire left kidney and the upper pole of the right kidney. AVF was created 28 days later by anastomosing the end of the left external jugular vein (LEJV) with the side of the left common carotid artery (LCCA). PTA was performed 28 days after AVF, and six animals were sacrificed 4 days later, and six animals after 42 days. 4D Flow MRI (3T Premiere, GE Medical Systems, Milwaukee, WI) was conducted every two weeks in the animals to be sacrificed on day-42 to measure the flow parameters. One animal had an infected fistula and was excluded from the study. After embolization, 28 days later, the average creatinine and BUN increased significantly (100.25 ± 4.31μmol/L vs 188.33 ± 6.30 μmol/L, p = 0.0004; 2.55 ± 0.06 mmol/L vs 3.35 ± 0.18 mmol/L, p = 0.0045 respectively). The average stenosis in 11 animals was 85 ± 3% on the day of PTA. Five of first six animals developed total occlusion of the outflow vein. To improve outcomes, the AVF technique was changed by increasing spatulation size and excision of the sternomastoid muscle resulting in improved patency of the outflow vein from 20% (1/5) in the first five animals to 83.3% (5/6) in the next six. The average diameter of the outflow vein was 9.7 ± 0.42 mm after AVF creation. After PTA, outflow vein diameter increased significantly compared to before (7 ± 0.40 mm vs 5 ± 0.72 mm, p = 0.043). Angiography revealed a significant reduction in percent stenosis of outflow vein after PTA compared with before (20 ± 5.48% vs. 78 ± 2.00%; p = 0.0079). On 4D Flow MRI, the outflow vein had higher blood flow at day-42 after PTA vs day-28 and day-14 (68.02 ± 8.68 mL/s vs. 49.13 ± 9.21 mL/s; p = 0.2268 and 40.31 ± 3.23 mL/s; p = 0.0608 respectively). Inflow artery lumen area increased significantly on day-42 after PTA vs day-14 (78.37 ± 6.32 mm2 vs 49.84 ± 4.54 mm2, p= 0.0068). A clinically relevant porcine model of PTA of AVF VS was established. Surgical techniques were refined, and PTA was assessed through angiography, and by conducting serial 4D Flow MRI scans. This model can be employed in future research to gain insights into the molecular mechanisms of restenosis and to aid in the design and manufacturing of novel drugs and medical devices.