Embolization of a large high-flow renal arteriovenous fistula using 035″ and 018″ detachable coils
A 45-year-old man with a past medical history of refractory hypertension presented with a progressively enlarging right renal AVF, which was incidentally discovered a year prior on a computed tomography (CT) scan of the abdomen, and demonstrated interval growth on the follow-up CT scan from a maximum diameter of 21 mm to 33 mm. Considering the increase in size, the patient's team decided to treat this AVF. However, the poor general medical condition secondary to non-ischemic cardiomyopathy precluded the option of total nephrectomy. CT angiogram (CTA) showed an enlarged main renal and posterior segment artery which fed a tortuous fistulous tract having many fusiform dilatations; the maximum diameter of the tract measured 33 mm []. Following an angiogram performed for selective embolization of the renal AVF, access to the right common femoral artery was obtained and a 5-French (F), 45-cm arterial sheath (Ansel sheath, Cook, Bloomington, IN, USA) was placed with its tip in the infrarenal aorta. The right renal angiogram revealed a large posterior segment branch, measuring up to 8 mm in diameter, supplying a tortuous fistulous tract and arising distal to the origin of the segmental branches []. This tortuous fistulous tract had multiple saccular aneurysms []. The maximum diameter of the aneurysmal portion of the fistulous tract measured 33 mm and was situated immediately distal to the arteriovenous communication. The posterior segment artery was selected using a Cobra catheter over a 035″ glide wire. The arterial sheath was further advanced over a super stiff wire into the main right renal artery for better support. A 3-F microcatheter having an inner diameter of 0.021 inches (Renegade, Boston Scientific Corporation) was advanced coaxially through the Cobra catheter over a 018″ wire (Transcend wire, Boston Scientific Corporation) into the fistula. Initially, a 018″ 14 mm × 30 cm IDC, which was the largest coil available at the time, was advanced through the microcatheter and partially deployed in the feeding artery. However, the coil was unstable in its position and prolapsed into the aneurysmal fistulous tract; the coil was subsequently withdrawn. The microcatheter was removed and a 035″ 50 mm × 40 cm IDC was advanced through the Cobra catheter into the feeding artery while maintaining a saline flush. The coil was deployed cautiously over 5 min. Once the loops were stable, the IDC was detached []. This initial coil served as a scaffold for the other coils. The 3-F microcatheter was reinserted coaxially through the Cobra catheter over a 018″ Transcend wire into the feeding artery. Then, a 018″ 10 mm × 30 cm fibered IDC was advanced through the microcatheter, and loops of the coil were deployed proximally in the feeding artery using the previously deployed coil as an anchor. Further coiling of the feeding artery was performed by a 018″ 10 mm × 30 cm and followed by seven 018″ 10 mm × 20 cm. Final angiogram demonstrated non-filling of the AVF with preservation of the remaining segmental branches. A nephrogram was noted in the final angiogram, which was not present in the initial angiogram, indicating redirected arterial flow from the AVF toward the renal parenchyma []. There were no complications during the procedure. Follow-up CTA obtained 6 months after the embolization demonstrated occlusion of the fistulous tract. Focal parenchymal atrophy in the posterior cortex corresponded to the vascular territory of the occluded segment.