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Vascular » Peripheral Vascular
Pseudoaneurysmal dilatation of a right femoral AV fistula
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Presentation A 50 year old man had a cardiac catheterization via the right femoral artery five months prior and he now presents with an ipsilateral groin mass. A bruit could be heard over the mass.
Caption: Transverse sonogram of the right groin.
Description: A large hypoechoic structure which shows posterior enhancement is seen in the right groin.
Caption: Transverse color Doppler scan.
Description: The hypoechoic mass seen in the right groin completely fills with color showing turbulent flow with a yin-yang pattern. A large vessel is seen in very close proximity to this structure.
Caption: Spectral analysis of the vascular mass.
Description: Spectral Doppler indicates very turbulent flow within the mass.
Caption: Color Doppler view.
Description: Two vessels are noted posterior to the vascular mass. One of them [a vein] shows a direct communication with the mass.
Caption: Spectral analysis at the site of communication.
Description: An abnormal venous waveform [it is arterialized] is noted at the site of communication between the vein and the mass.
Caption: Spectral Doppler of the common femoral vein.
Description: A normal waveform is seen in the common femoral vein.
Caption: Spectral analysis of the second vessel.
Description: A second vessel was also noted to be communicating with this mass. It demonstrated an arterial waveform [which is a low resistance flow] and the vessel appears to be a proximal branch of the right common femoral artery.
Caption: Doppler of the proximal common femoral artery.
Description: A normal arterial waveform [high resistance] is noted.
Differential Diagnosis A large arteriovenous fistula between the common femoral artery and vein.
Final Diagnosis Aneurismal dilatation of an arteriovenous fistula between a branch of the right common femoral artery and the underlying femoral vein.
Discussion Vascular complications following femoral artery catheterization are on the rise due to wide usage of larger bore catheters and sheaths, longer duration of complex interventional procedures and extensive anticoagulation during the procedure. Iatrogenic pseudoaneurysms and arteriovenous [AV] fistulae of the femoral artery account for less than one percent and are among the most common vascular masses. The former is slightly more common and has been discussed in an earlier case.

AV fistulae can be easily diagnosed with color Doppler ultrasound. According to Kurtz, et al, focal hemodynamic changes can be detected within about 1-2 cm of the actual communication and can be very striking. The site of AV fistulae often has a high velocity blood flow and this may result in turbulence and focal perivascular tissue vibration, resulting in an array of colors in the perivascular soft tissues. Spectral analysis of the artery supplying the fistula [as in this case] may show decreased resistance manifested as higher diastolic flow velocities and persistent forward flow throughout the cardiac cycle. This pandiastolic antegrade flow contrasts with the normally absent or reversed diastolic flow that occurs in most peripheral arteries. The communicating vein may also show a turbulent flow with an arterialized venous pattern.

According to a few reports, AV fistulae with small shunt volume may spontaneously close. But in most cases surgical repair, endovascular repair via the placement of stents and coils and percutaneous ultrasound guided procedures such as compression therapy [for small AV fistulae] are some of the modes of treatment for the patients with AV fistulae. Once the fistula is repaired, monitoring by ultrasound can be easily carried out. Thus with the increasing incidence of post femoral artery catheterization fistulae, careful monitoring by non invasive modalities must be considered for early diagnosis and intervention.

Case References 1. Kurtz, Alfred B. and William D. Middleton. Ultrasound: The Requisites. New York: Mosby, 1996.
2. Kesseler J, Mohler ER. Arteriovenous fistulas of the lower extremity. UpToDate Version 11.2: April, 2003.
3. Perings SM, et al. A prospective study on incidence and risk factors of arteriovenous fistulae following transfemoral cardiac catheterization. Int J Cardiol. 2003 Apr; 88(2-3):223-8.
4. Kelm M, et al. Incidence and clinical outcome of iatrogenic femoral arteriovenous fistulas: implications for risk stratification and treatment. J Am Coll Cardiol. 2002 Jul 17; 40(2):291-7.
5. Perings SM, et al. Duplex ultrasound determination of shunt volume in iatrogenic arteriovenous fistulas after heart catheterization. Z Kardiol. 2002 Jun; 91(6):481-6.
Follow Up This patient underwent an angiography and a large communication was detected between a branch of the right common femoral artery and vein. This was successfully embolized and a follow up Doppler showed no flow within the aneursymal dilatation of the AV fistula.
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