Acquired Arteriovenous Fistulas

Iatrogenic Arteriovenous Fistulas

Iatrogenic injuries that cause AVFs usually result from percutaneous cardiac and vascular diagnostic and therapeutic interventions, central venous catheterization, orthopedic procedures on the lumbar spine and knee, diagnostic kidney and liver biopsies, and percutaneous insertion of biliary and urinary drainage catheters. The right common femoral artery (CFA) remains the most common site of iatrogenic injury (37%) in the lower extremities. The increase in the number of percutaneous interventions being performed would be expected to result in a greater number of iatrogenic AVFs. However, the use of micropuncture angiographic needles inserted under ultrasound (US) guidance and small diameter sheaths has significantly reduced the number of access site–related complications (1.9% vs. 4.3%) in patients undergoing coronary angiography. In a prospective study of 635 patients undergoing femoral access for noncardiac diagnostic or interventional procedures randomized 1:1 to receive either fluoroscopic or US-guided access, the authors found that although the use of ultrasound guidance allowed for more efficient and expeditious cannulation of the femoral artery, the rates of early or late complications did not differ between the two groups.

Innominate Artery Arteriovenous Fistulas

Innominate artery injuries account for 0%–3% of civilian arterial injuries and result from GSWs, SWs or central venous catheterization of the internal jugular and subclavian veins. Fistulas between the innominate artery and the superior vena cava, innominate vein or its tributaries were present in 10% of patients in a series reported by du Toit et al. ( Fig. 173.4 ).

Carotid Artery Arteriovenous Fistulas

Carotid artery injury constitutes 5% to 11% of all arterial injuries and usually results from SWs or GSWs, therapeutic or diagnostic catheterization, or blunt trauma to the skull or cervical spine. AVFs between the carotid artery and internal jugular vein or its tributaries occurs following 4% to 27% of such injuries. ^{, , ,}

Vertebral Artery Arteriovenous Fistulas

Vertebral artery AVFs occur in 0.7% to 7.4% of cases of penetrating trauma. The AVF is usually between the vertebral artery and the epidural venous plexus and/or jugular venous system. Iatrogenic injury during operative procedures on the cervical spine and catheterization of the internal jugular vein accounts for approximately two-thirds of cases, while cervical spine fractures due to blunt trauma, chiropractic manipulation, or closed head injury, GWs, and SWs for the remaining one-third. Spontaneous AVFs are rare usually due to an underlying collagen vascular disease such as neurofibromatosis type I, Marfan and Ehlers–Danlos syndromes.

Axillary and Subclavian Arteriovenous Fistulas

Approximately 3% of all neck- and chest-penetrating trauma is associated with injury to the subclavian vein (44%), artery (39%), or both (17%). Inadvertent puncture of the carotid or subclavian arteries occurs in up to 8.4% of cases of attempted central venous catheterization, ^, and the incidence of AVFs following subclavian vein catheterization is estimated at 0.58%. Penetrating axillary artery injuries and fractures of the clavicle or first rib are rare causes of AVFs. ^,

Brachial, Radial, and Ulnar Arteriovenous Fistulas

Upper extremity trauma accounts for 25% to 40% of all VIs. ^, The brachial and forearm arteries are involved in 10% to 22% of cases. The radial and ulnar arteries are frequently used for cardiac and endovascular interventions; AVFs occur in 0.02% to 0.04% of cases. Peripherally inserted central catheter (PICC) lines may also be complicated by AVFs.

Femoral Arteriovenous Fistulas

Penetrating injuries due to GSWs, SWs, shrapnel injuries from IEDs, or following surgery for intertrochanteric or femoral neck fractures may result in femoral AVFs. ^{, ,} The incidence of AVFs as a result of such injuries varies considerably between the military and civilian populations. In a review of 558 AVFs due to military injuries, 28% involved the superficial femoral or profunda femoris arteries, whereas in a civilian series of AVFs predominantly due to SWs, the CFA was involved in 12% of cases ( Fig. 173.5 ). Sporadic cases of spontaneous AVFs between the superficial femoral artery and vein have also been described. The CFA remains the most common site of iatrogenic AVFs, with an incidence of 0.06% to 0.86% when diagnosed by physical exam but 2.8% using duplex US (DUS). ^, Femoral AVFs are slightly more frequent after interventional than diagnostic procedures. The majority of AVFs close spontaneously: in one study, only 11% became symptomatic and required operative repair (OR). Femoral and external iliac artery AVFs are a rare complication of endovenous laser ablation for varicose veins. ^, The risk factors predisposing to iatrogenic femoral AVFs are listed in Box 173.1 .

Popliteal Arteriovenous Fistulas

Popliteal AVFs have similar etiologies to femoral AVFs. They account for approximately 16% of AVFs reported in the Vietnam registry and 5% to 14% of civilian AVFs. ^{, ,} Blunt trauma associated with comminuted femoral and proximal tibial fractures and orthopedic procedures on the knee may also be complicated by AVFs. ^, The number of iatrogenic popliteal AVFs can be expected to increase, due to the more frequent use of popliteal access for interventions to treat deep vein thrombosis and chronic venous insufficiency.

Tibial and Peroneal Arteriovenous Fistulas

AVFs of the tibial and peroneal arteries are a recognized complication of comminuted fractures, blast fragment injuries, balloon catheter thrombectomy, and atherectomy of the tibial vessels ( Fig. 173.6 ). Approximately 24% of the AVFs reported in the Vietnam registry occurred in the tibial and peroneal arteries. The more frequent use of retrograde tibial access to recanalize occluded lower extremity arteries in patients with critical limb ischemia (CLI) may increase the risk of AVFs in these locations.

Aortoiliac Arteriovenous Fistulas

Rupture or erosion of an AAA into the IVC accounts for 80% to 90% of acquired aortocaval fistulas (ACFs). GSWs, shrapnel, SWs, iatrogenic injury, lumbar disk surgery, and nephrectomy account for the remaining 10% to 20% (see Fig. 173.1 ). Persistent or recurrent ACFs may occur due to the failure to detect or adequately repair the fistula, rupture of a para-anastomotic PSA into the IVC (distal anastomosis of aortic tube grafts), and ongoing pressurization of the aneurysm sac because of persistent endoleaks.

Iliac AVFs account for 0.4% to 1.4% of AVFs and are usually the result of rupture of an iliac aneurysm into an adjacent vein, penetrating trauma or lumbar disc surgery. ^{, ,}

VI occurs in up to 0.05% of lumbar disc procedures. Anatomic anomalies, such as a low aortic bifurcation at L4–L5 (18%) and degenerative changes of the anterior spinal ligament, may contribute to VIs in this location. VIs at the L3–L4 disc space predominantly involve the aorta and IVC; the majority of iliac VIs occur at the L4–L5 and L5–S1 disc space, where the common iliac arteries are most vulnerable to injury (right CIA 43%; left CIA 29%). ^,

Renal Arteriovenous Fistulas

The majority of renal AVFs occur after renal biopsy in approximately 9% to 18% of patients. Factors predisposing to biopsy-related renal AVFs include use of a large-bore needle, lack of US or CT guidance when performing the biopsy, medullary penetration, and the presence of atherosclerotic vessels ^, ( Fig. 173.3 ). Iatrogenic causes resulting from surgical or percutaneous interventions including partial nephrectomy, mass ligation of the renal pedicle, guide wire arterial perforation during angiography or renal stenting, percutaneous nephron-lithotomy, laser lithotripsy and percutaneous nephrostomy tube placement comprise most of the remainder. Spontaneous renal AVFs may occur from the erosion of tumors, inflammatory processes, or of an aortic or renal aneurysm directly into a retro-aortic or normally located renal vein or its tributaries. ^{, , ,} Isolated renal AVFs due to blunt and penetrating trauma are uncommon.

Splenic, Hepatic, and Mesenteric Arteriovenous Fistulas

Splenic AVFs may result from blunt or penetrating intraabdominal trauma, mass ligation of the splenic pedicle, iatrogenic injury during splenoportography, and, rarely, erosion of a pancreatic pseudocyst into the splenic artery and vein. Forty-four percent of splenic AVFs are due to rupture of a noncalcified splenic artery aneurysm (SAA) into an adjacent vein; this may be the first indication of the presence of an SAA. ^, Hepatic AVFs are most commonly the result of penetrating or vehicular trauma but may occur after percutaneous needle biopsy, transhepatic diagnostic catheterizations, biliary drainage, or TIPS procedures ( Fig. 173.8 ). Hepatic AVFs may be either intrahepatic or extrahepatic and occur in 5.4% of patients after percutaneous needle biopsy. Hepatic artery aneurysms (HAAs) and carcinomas may also erode into an adjacent vein, resulting in an AVF. ^{, ,} AVFs of the superior and inferior mesenteric arteries are rare and are usually the result of penetrating trauma, iatrogenic injuries, or mass ligation of the vascular pedicle during bowel resection. ^,

Uterine Arteriovenous Fistulas

Acquired uterine AVFs are a rare complication of intrauterine instrumentation procedures, (diagnostic and therapeutic curettage, removal of retained placental products, IUDs, and hysteroscopy) myomectomy, and pathologic processes such as infection, trophoblastic disease, and malignancies involving the uterus. Uterine AVFs are frequently a single AV communication without involving the surrounding tissue. ^,