Thanks to the minimally invasive characteristics, endovascular therapy has been the mainstream in the therapy of splanchnic aneurysms. Endovascular therapies are superior to surgical interventions in the hostile abdomen, where dense adhesion occurs due to recent surgeries or chronic inflammation. The commonly used endovascular therapies for the aneurysm include coil angioembolization to exclude aneurysms in expendable vessels and endovascular stent to keep the patency of the nonexpendable parent vessel and the exclusion of the aneurysm concomitantly (14-16). The feasibility of endovascular therapy in splanchnic aneurysms is determined by vascular anatomy (14, 16). Needs for a sufficient working landing zone and the risk of blocking nearby vascular branches limit the application of endovascular stents in splanchnic aneurysms (16-18).
On the other hand, the risk of coil angioembolization includes coil migration-related non-target ischemia (19); incomplete exclusion of the aneurysm (16); requirement of multiple coils for sac packing in giant aneurysms; incomplete thrombosis in ruptured aneurysms when hemorrhagic shock-related coagulopathy develops (16). Corresponding to the current guideline, our patients received endovascular trials first, followed by salvage operations if endovascular therapy failed (5). Insufficient landing zone for deploying stent due to the tortuous vascular anatomy and high risk of coil migration-related non-target ischemia due to high intra-luminal vascular flow accounted for failed endovascular therapies in cases - 1 and 2. Fear of losing nearby critical vascular branches after deploying endovascular stent and incomplete exclusion of the aneurysms by coil angioembolization accounted for failed case - 3. In case - 4, a residual arterial backflow and a mass effect caused by the giant hematoma after proximal angioembolization made us have to offer a salvage surgery. Therefore, we considered that the success rate of endovascular therapies in the splanchnic aneurysms near the pancreas might not be so high as other positions because of its unique anatomic positions (i.e., tortuous, redundant, highly variable, and high-flow vascular system).
While the endovascular approach fails, surgical intervention will be a choice. Conventionally, to isolate and control proximal and distal vessels, followed by aneurysmectomy and end-to-end vascular reconstruction will be a standard procedure to treat the aneurysm and maintain vascular continuity (5). Nonetheless, the procedure needs to create a proper surgical field for engaging it, and it may cause ungrateful bleeding and unexpected injuries to the surrounding organs, particularly in chronic pancreatitis, which is the most common etiology of false splanchnic aneurysms, and also accounted for 50% of our patients (8). Moreover, lengthy adhesiolysis in the hostile abdomen secondary to chronic pancreatitis or recent operations is often associated with an increased risk of perioperative complications (20-22). Hence, this might be why open surgery carries a higher complication rate than endovascular therapy in some studies (4, 10).
Since endovascular therapy is widespread, studies regarding surgical interventions for splanchnic aneurysms are relatively few. Pulli R et al. published their 25-year experience in managing splanchnic aneurysms (1). As a cardiovascular surgical team, their surgical goal focused on restoring normal vascular flow. Thus, around 50% of cases received aneurysmectomy with end-to-end vascular anastomosis even in the areas where abundant collateral flow exists (e.g., peripancreatic artery, splenic artery, or gastric arteries). Besides, they also performed aneurysmectomy with primary or patch closure or arterial ligature. However, they did not mention the criteria for choosing different surgical approaches. They reported that surgical intervention has good long-term outcomes. However, they also reported a case of mortality secondary to post-operative pancreatitis after they did aneurysmectomy with end-to-end anastomosis for splenic artery aneurysm. This report corresponded well to our assumption that extensive dissection in the hostile abdomen for preparing end-to-end vascular reconstruction may predispose the accidental injury and cause subsequent morbidity and mortality.
In the perspective of general surgeons, we have a slightly different philosophy to treat splanchnic aneurysms. If the aneurysm is embedded inside the parenchyma and cannot be controlled by endovascular therapy, we favor excising the aneurysm along with end-organ (e.g., splenectomy for the aneurysm inside the spleen). If the aneurysm is located outside the parenchyma of solid organs, we will try to control the aneurysm's proximal and distal vascular end first, followed by aneurysmectomy and end-to-end anastomosis (23). Nevertheless, when dissecting the vessels in the hostile abdomen is inviable, we adopted the surgical concept of directly repairing femoral and iliac artery aneurysm (24-26). Even in a dense adhesion region, directly opening the vascular wall of the aneurysm and closing the orifice of the feeding vessels like distal and proximal embolization by coils (i.e., Sandwich technique) can still be done quickly. Since the collateral circulation in the peripancreatic area is abundant, except for some nonexpendable vessels (e.g., SMA trunk, proper hepatic artery), proximal and distal ligation of the aneurysm can be done safely without compromising perfusion of the distal organ (e.g., our case - 3 and 4: SMA branch aneurysm and dorsal pancreatic aneurysm). We believe that our criteria of selecting surgical approaches for splanchnic aneurysms could avoid accidental injuries caused by surgical dissection at the hostile abdomen and reduce the risk of perioperative morbidity.
Either surgery or endovascular therapy as the most appropriate treatment for giant splanchnic aneurysms (i.e., diameter >5cm ) remains undetermined, particularly for the aneurysm with concomitant mass effect (2, 33-36). Some authors preferred open surgery because embolization with thrombosis of the aneurysm cannot resolve the mass effect immediately (33). However, successful remission of obstructive jaundice by embolization to the splanchnic aneurysms was also reported sporadically (2, 34, 37). Tipaldi et al. displayed their experience using endovascular therapy to giant splanchnic artery aneurysms in 11 cases, and one case obtained resolution of jaundice after embolizing the aneurysm (2). However, considering technically challenging and high cost, they also stated that endovascular therapy should be listed as the first-line treatment for the giant aneurysm only when the necessary expertise and resources are fully available and the patients’ hemodynamic condition is stable (2).
Back to our experience, we think the giant aneurysm does not necessarily need surgical intervention if endovascular therapy is available and successful. However, if the giant aneurysm occurs in association with mass effect (e.g., obstructive jaundice or bowel obstruction), surgical intervention could be an alternative to provide immediate resolution of the aneurysm and its associated compression. Following our treatment philosophy, incising and exploring the giant aneurysm, suturing the bleeder from the inner lumen, and emptying the contained hematoma for immediate resolution of mass effect would be feasible and straightforward for any well-prepared surgical team. Noteworthy, because obstructive jaundice may be caused by either the giant aneurysm or underlying chronic pancreatitis, surgeons should rule out residual biliary stricture by intraoperative cholangiography after successful treatment for the giant aneurysm with associated jaundice (33). If residual biliary stricture exists, concomitant bilioenteric bypass or post-operative endo-biliary drainage may be needed.
The residual or recurrent aneurysm after the primary surgical repair has rarely been discussed. After initial surgical repair, re-operation for a residual aneurysm is not always technically feasible because of significant inflammation and adhesion after recent operations (22). Instead, endovascular therapy for the post-operative false aneurysm has been widely accepted due to its efficacy and safety (22). Sachdev et al. and Spiliopoulos et al. both highlighted a highly successful rate of the repeated endovascular procedure after incomplete exclusion of splanchnic aneurysms following initial endovascular treatment (7, 38). Therefore, we consider endovascular therapy the best choice after incomplete exclusion of the aneurysm following open vascular surgery. However, if the patient suffers an asymptomatic, small-sized aneurysm with significant medical comorbidities or limited life expectancy, we could keep close observation rather than reinterventions, unless the aneurysm show interval growth from the surveillance imaging (5). In our case - 1 (celiac artery aneurysm), an 8-mm residual aneurysm was found six months later. Given the small size (< 2cm) of the aneurysm, asymptomatic status, and patient's limited life expectancy due to severe liver cirrhosis, we adopted conservative treatment with blood pressure control and regular follow-up with serial imaging studies, which is consistent with the latest guideline of the management of splanchnic aneurysms (5).
The limitation of this study includes a small number of cases and the lack of long-term follow-up. Nevertheless, this study focuses on the appropriate management after failed endovascular therapy for splanchnic aneurysms and giant aneurysms with associated mass effects. Because both conditions are rarely discussed, our successful experiences on salvage surgeries for splanchnic aneurysms with failed endovascular therapies and its short-term outcomes are still valuable.
In summary, selected true or all false splanchnic aneurysms warrant timely intervention. Surgical management is a feasible, effective, and safe alternative for splanchnic aneurysms undergoing failed endovascular therapy or for giant aneurysms with associated mass effects.