Visceral artery aneurysms: Incidence, management, and outcome analysis in a tertiary care center over one decade

The purpose of this study was to investigate the incidence, aetiology and current management of VAA at our university medical centre. The overall incidence of VAA was relatively low, with a total of 233 patients presenting with 253 VAAs over a 10-year period. The most frequent aetiology was degenerative/atherosclerotic, which accounted for more than two-thirds of all cases. The second most frequent aetiology was complications after preceding medical procedures, with a 9.1 % rate of iatrogenic false aneurysms. Vasculitis and diverse specific connective tissue disease were uncommon causes of VAA [11‐19].

The prevalence of VAA is reported to be 0.1–2 % [20, 21]; however, the number of undetected VAAs may be much higher. The clinical presentation is nonspecific in most cases, and the diagnosis of VAA is often an incidental finding. It is the general consensus that symptomatic VAA should be treated immediately, since rupture is associated with a high mortality rate [9, 22, 23]. A wide range of rupture rates have been reported [20‐22, 24, 25], and emergency treatment of ruptured VAA has mortality rates of up to 30 % [26, 27]. In our patients, VAA rupture resulted in intraperitoneal, retroperitoneal and gastrointestinal bleeding, as well as bleeding into adjacent organs. A striking number of VAA ruptures occurred after medical procedures. In our study, the 30-day mortality rate was comparably low in these cases; however, there was a considerable complication rate after interventional treatment and open surgery (12.5 % and 18.2 %, respectively).

The decision to treat or not to treat asymptomatic VAA poses a challenge in elective cases [24, 27‐30], and the treatment modality used varies based on location, clinical symptoms and co-morbidities [24, 28]. There are no evidence-based data to rely on, and individual treatment decisions are based on clinicians’ experience and the technical facilities of the interventional radiologist or surgeon. According to the guidelines, treatment is suggested for VAA with diameters >2 cm or if the VAA is three times greater in diameter than the respective normal artery [9, 24, 29]. However, we did not find any difference in mean diameters between ruptured and non-ruptured aneurysms. Therefore, VAA diameter alone appears to be an inadequate criterion for decision making [24, 31, 32]. At our institution, treatment decisions for individual cases are based on an interdisciplinary discussion including the aetiology of the aneurysms and all clinical aspects of the particular case. To determine other possible risk factors, we tried to identify additional criteria. In our series, pseudoaneurysms presented with a significantly increased risk for rupture, with 76.3 % of pseudoaneurysms being ruptured. By comparison, true VAA presented with a rupture rate of 3.1 %. Whether beta blockers have a preventive effect is still a matter of debate [24, 31]. Aneurysm calcification indicates a longstanding and therefore probably more stable aneurysm. In our series, 27.3 % of non-ruptured VAAs presented with some calcification, whereas none of the ruptured cases did. Parietal thrombosis was not associated with rupture risk in our series. Patients with ruptured VAAs were slightly less likely to be taking beta blockers compared to those with non-ruptured VAAs (35.1 % vs. 37.5 %, respectively). Steroid usage was slightly higher in the group of patients with ruptured VAAs.

The distribution of VAAs in our study was mostly in concordance with the literature. SAAs are reported to be the most frequent VAA; they account for up to 60 % of all VAAs [5, 6]. Bedford et al. [6] discovered 10.4 % SAAs in a routine post-mortem study of 250 bodies. Our data confirm that SAAs occurred with the highest frequency; SAAs accounted for 32.8 % of all VAAs, with a female:male ratio of 1.2:1. Common risk factors for SAA are female gender, pregnancy and portal hypertension [21, 28]. None of our patients were pregnant, and only one was of reproductive age. Recent reports have suggested an increasing incidence of HAA, which can be attributed to the more-frequent use of CT imaging after blunt liver trauma and hepatobiliary intervention [22, 33, 34]. A total of 17.5 % HAAs had a history of pancreaticoduodenectomy or biliary tract intervention. With respect to superior mesenteric artery aneurysm (SMAA) and aneurysms involving smaller branches of the coeliac trunk (gastric, pancreaticoduodenal and gastroduodenal arteries), our data are similar to that of other reports, with a 6.7 % prevalence of SMAAs ([5, 35] and 7.1 % prevalence for aneurysms in branches of the coeliac axis [20]. Coeliac trunk aneurysms (CTRA) have been reported to be associated with abdominal aortic aneurysms [24], which is consistent with our data. In contrast to recent reports, we noted a strong predominance of men (95.7 %) in these cases [29]. Also in contrast to the literature, our analysis detected 18.6 % CTRAs; however, most of these were characterized as degenerative lesions or poststenotic dilatation of the coeliac trunk. Only one CTRA was indicated for treatment. Stenosis is an often-described risk factor for the development of VAA of the coeliac trunk arteries and SMA [4, 23, 29, 36‐39], which is supported by our data. RAAs also were included in our analysis; the incidence of RAAs in our study was higher than that reported in the literature [21]. RAAs seem to be associated with fibromuscular dysplasia and medial degeneration. Hypertension is reported to be another risk factor for RAA [8, 24, 40] and was evident in 63.6 % of our patients.

The favoured interventional treatment modalities for VAA include transcatheter embolization and stent grafting [24, 41]. In our analysis, embolization was performed with either pushable coils, detachable coils, glue embolic fluid, or combinations thereof, at the discretion of the investigators. Onyx liquid embolization had not yet been introduced for peripheral indications at our institution at that time. The stent grafts used were provided by various companies and were employed based on the location of the VAA, the size required, and the personal experience of the investigator. Flow diverter stents might have served as an alternative in particular cases, but they had also not yet been introduced at our institution. In contrast to open surgery, interventional procedures are normally performed under local anaesthesia, with high technical success rates [4, 20, 23, 34, 41], low complication rates, and shorter hospital stays [31, 42]. Reported complications include technical failure to catheterize the artery [43], arterial thrombosis or embolism resulting in organ infarctions or abscesses, coil migration, aneurysm recurrence, and a haematoma or a pseudoaneurysm at the arterial puncture site [24, 27, 30, 41, 44]. Our data analysis yielded a technical success rate of 93.3 % (42 of 45 aneurysms). Technical failures included one case with migration of a covered stent in an RAA, which was treated with subsequent coil embolization. In another case, coil embolization of a false RAA resulted in an incomplete occlusion, which required reintervention. In the third case, elective coil embolization of an SAA presented some coil migration, with consequent ischaemia of the spleen and pancreas.

There was a complication rate for interventional treatment of 13.3 % (four complications in 30 patients) in emergency cases compared to 10 % (one complication in ten patients) in elective cases. Rebleeding as a late procedural failure occurred most frequently after coil embolization. There was no mortality in elective cases but a 30-day mortality of 6.7 % in emergency cases after interventional treatment, with one case of intracerebral bleeding and one patient with right heart failure after rebleeding. This is very low in comparison to other series published [4, 5, 34], only Balderi et al. [26] presented a 30-day mortality comparable to ours. Our data are, however, not suitable to achieve a comparative outcome analysis after surgical and interventional treatment. While most surgical patients received an elective operation, the majority of emergency cases were treated by means of interventional techniques. Moreover, the number of surgical cases was too small to reliably draw comparative data with respect to 30-day mortality or complication rates. The retrospective analysis of the practiced interdisciplinary decision making and the acceptable complication rates as reported above give the impression that the interventional treatment options are the treatment of choice both, in emergencies as well as in elective cases.

In conclusion, diagnoses of VAA may have increased because of increasing numbers of cross-sectional imaging studies; the incidence of SAAs was highest. We also observed significant numbers of aneurysms of the coeliac trunk arteries and renal artery, which suggests that these VAAs may be currently underdiagnosed. The mean diameter of ruptured aneurysms did not significantly differ from that of non-ruptured aneurysms. Thus, treatment indications should not be based primarily on the aneurysm diameter, but in the first instance on the aneurysm aetiology. Pseudoaneurysms need emergency treatment. The vast majority of true aneurysms can probably be managed conservatively; however, there might be some potential for fatality due to secondary aneurysm rupture.