Page 56 - Read Online

Wang et al. Vessel Plus 2018;2:7 I http://dx.doi.org/10.20517/2574-1209.2018.15 Page 3 of 5

A B

Figure 2. Postoperative surveillance CTA demonstrated successful exclusion of the SMAVF and loss of venous collaterals on both coronal
(A) and sagittal (B) projections. CTA: computed tomographic angiogram; SMAVF: superior mesenteric arteriovenous fistula

communicating fistulas, and reduced SMV and portal vein size [Figure 2]. Most importantly, his abdominal
discomfort resolved. The patient was again seen in clinic at 14-month postoperatively where a mesenteric
duplex demonstrated a widely patent SMA stent in an asymptomatic patient.

DISCUSSION
SMAVF is most commonly caused by penetrating abdominal trauma or iatrogenic injury during
abdominal surgery. Specifically, this complication has been observed after small bowel resection, colectomy,
aortobifemoral bypass, and kidney-pancreas transplantation . The clinical manifestations of SMAVF
[3,4]
may vary from completely asymptomatic to nonspecific abdominal pain, anorexia, nausea, diarrhea,
gastrointestinal hemorrhage, signs of portal hypertension, and even congestive heart failure secondary to
a persistent high-flow state . The most common physical findings are the presence of a machine-like bruit,
[5]
palpable abdominal mass, or a thrill over the abdomen.

Mesenteric duplex can be used as the initial diagnostic imaging modality as it does not have any associated
risks related to radiation or contrast administration. While specificity may be high with this study, sensitivity
can be lacking - particularly in the morbidly obese patient. Therefore, CTA with both an arterial and venous
phase should also be considered as the confirmatory diagnostic modality. However, the gold standard for
diagnosis, continues to be intraoperative DSA which carries the highest sensitivity and specificity. In our
patient, DSA was used to define the area of vascular defect intraoperatively. Unfortunately, in the setting of
significant venous congestion, near-instant filling of arterial and venous collaterals can make delineation
of vascular anatomy difficult, even with the benefit or orthogonal angles. In these situations, IVUS in the
suspected vascular territories can help identify the exact site of defect for stent coverage.

Endovascular treatment has supplanted open ligation secondary to low morbidity and a desire to avoid
laparotomy in a reoperative abdomen. Coil embolization, vascular plugs, and covered stents have all been
deployed with varying success. A literature review demonstrates at least 25 instances of endovascular
SMAVF repair consisting of 16 cases with coil embolization, two cases with vascular plugs, six cases
with covered stents, and one patient repaired with a combination of both coil embolization and covered
stent exclusion . Coil embolization, while effective at fistula exclusion, is associated with a high risk of
[5-7]
postoperative migration and inadvertent thrombotic events and should be avoided if possible. For example,
three of the coil embolization procedures were complicated by portal thrombosis. While two were self-
limited and resolved after heparinization , the third patient died from multiorgan failure . Additionally,
[1]
[8,9]