Arteriovenous fistulas (AVFs) are abnormal connections between arteries and veins that bypass the normal anatomic capillary beds. AVFs of the lower extremity can be divided into congenital and acquired causes. Iatrogenic causes, primarily occurring during cardiac catheterization, are the most common etiology. These may ensue when a needle tract crosses both femoral the artery and vein, and is then dilated during catheterization, creating a communication between the vessels after catheter removal. In three large series from experienced cardiac catheterization centers, the incidence of AVF was 0.1-0.2%. Similar values have been noted with the use of arterial closure devices. Other femoral arterial complications include pseudoaneurysm formation, hematoma, groin hemorrhage that may require transfusion, and arterial occlusion. Risk factors for AVF formation during catheterization include low femoral arterial puncture, large arterial sheath size, older age, and prolonged anticoagulation or fibrinolytic therapy. The incidence is higher in therapeutic compared to diagnostic catheterization (0.9 versus 0.2% in one report).

Almost all AVFs are clinically silent early in the postcatheterization period. If untreated, the time of onset of clinical presentation ranges from two days to several months after catheterization. Clinical complications include lower extremity edema, varicose veins, nerve compression, the development of or worsening of intermittent claudication, and rest pain secondary to distal ischemia. The most significant complication is the development of high-output heart failure which, in an older report, was estimated to occur after 0.01 to 0.02 percent of cardiac catheterizations.

Early diagnosis is dependent upon careful examination of the groin area, with evaluation for a femoral bruit, large hematoma, decreased or absent lower extremity pulses, or a groin pulsatile mass. Any of these findings is suggestive of a vascular complication and needs to be investigated further. Prior to the development and widespread use of ultrasound-Doppler technology, AVFs were suspected on clinical findings and diagnosed with an arteriogram. However, Doppler ultrasound is the current diagnostic test of choice in evaluating patients with suspected AVFs. The ultrasound image appears as a blush in the extremity and the connecting artery and vein can often be identified.

Because of greater awareness and ease of diagnosis, AVFs come to attention and, if necessary, are treated early. On the other hand, small AVFs are often monitored with ultrasound imaging. Indications for intervention are lack of spontaneous closure, increase in fistula size, and/or the development of symptoms. Surgical repair is the most common approach for fistulas that need closure, but other modalities have been evaluated. These nonsurgical alternatives may be particularly important in patients treated with aggressive antiplatelet therapy. One method is ultrasound-guided compression repair or closure (UGCR). This technique involves placing the ultrasound probe on the skin over the AVF and then compressing the area (usually for ten minute periods) with a sufficient force to abolish flow through the fistula without sacrificing distal perfusion of the leg. Compression results in stasis of blood in the fistula and secondary thrombosis. UGCR has been used successfully in pseudoaneurysms after cardiac catheterization, but only limited data are available for AVFs with variable success.

Preliminary data suggest that percutaneous approaches also may prove to have a role. One report evaluated 53 patients, 21 with an AV fistula and most of the remainder with a pseudoaneurysm, who failed repeated attempts at UGCR. The patients were primarily treated with either implantation of a covered stent or coil embolization. The procedure was successful in 47 (89 percent). Follow-up documented closure of all lesions, but four late stent occlusions occurred at three to six months. This study and other early investigations are suggestive that percutaneous interventions such as stent placement or embolization may be effective measures to avoid surgical repair when UGCR fails to result in obliteration of the AVF.