By Rabih A Chaer
Visceral artery aneurysms are rare with an incidence as low as 0.1–2% in the general population. Though the morbidity and mortality associated with repair of intact visceral artery aneurysms is low, ruptured visceral artery aneurysms pose a significant risk of complications and death.
While endovascular techniques have been widely described for the treatment of intact visceral artery aneurysms, their use in the setting of rupture has been only described in small case series.
In a recent series of visceral artery aneurysms from the University of Pittsburgh Medical Center, 181 patients were repaired (77 ruptured; 104 intact). The perioperative complication rate was higher for ruptured aneurysms (13.7% vs. 1% intact, p=0.003) as well as 30-day mortality (13% vs. 0% intact, p=0.001), one year (32.5% ruptured vs. 4.1% intact, p<0.001) and three years (36.4% ruptured vs. 8.3% intact, p<0.001). Lower 30-day mortality was noted with endovascular repair for ruptured aneurysms (7.4% vs. 28.6% open, p=0.025). Predictors of mortality for ruptured visceral aneurysm included age (OR=1.04, p=0.002) while endovascular repair was protective (OR=0.43, p=0.037). The majority of ruptured aneurysms were located in the splenic arterial bed (28.5%), followed closely by pancreaticoduodenal artery (26%), hepatic artery (22.1%), and subsequently superior mesenteric artery (10.4%), coeliac axis (5.2%), and renal artery (2.6%). Ruptured visceral aneurysms in the hepatic and pancreaticoduodenal arteries were much smaller in size than their intact counter parts (Figure 1).
Endovascular interventions typically include isolation, coil embolisation/packing, covered stent grafting, the use of liquid embolic agents, and percutaneous thrombin injection. General technical principles include the use of a triaxial sheath and catheter system, microcatheters, plugs for large vessel occlusion, and retractable detachable coils and superselective embolisation in order to minimise end organ embolisation. The choice of intervention typically depends on the patient’s anatomy, access vessels, location of the aneurysm, and whether the affected vessels supply a vital organ and need to be preserved.
Isolation requires ablation of both inflow and outflow vessels, with coil or plug embolisation distal and then proximal to the sac. It may need to selectively embolise side branches to prevent endoleak and is used in situations where the target vessel does not supply a vital organ. On the other hand, coiling and packing of the actual aneurysm is used for pedunculated aneurysms fed by essential vessels where inflow and outflow coiling is not possible, and in aneurysms with multiple side branches. Covered stents are particularly useful when preservation of the target vessel is essential, but can be limited by access vessel kinks and tortuosity, a bulky delivery system, and size discrepancy in the target vessel. Self-expanding stents are usually used. The main advantage is maintaining in-line flow and organ preservation. In addition, follow-up surveillance imaging with CT scanning is not limited by artifact which is typically the case after coil or plug embolisation. Future technologies involve the use of multilayer flow diverting stents which still need to be evaluated in clinical trials for this indication.
In summary, current endovascular interventions appear to be effective for the treatment of intact and ruptured visceral artery aneurysms, and are durable with a low rate of reinterventions. Our data particularly supports an endovascular first strategy for ruptured visceral artery aneurysms since it results in lower morbidity and mortality. In addition, pancreaticoduodenal aneurysms and all visceral pseudoaneurysms carry a high risk for rupture and should be repaired regardless of size.
Rabih Chaer is a professor of Surgery, Division of Vascular Surgery, University of Pittsburgh Medical Center, Pittsburgh, USA