An infected aortic aneurysm (IAA) is a rare but life-threatening condition [1,2]. It results from an arterial wall infection caused by septic emboli, hematogenous spread, or direct extension of an adjacent infectious process [3-5].

The high risk of rupture makes early and sometimes non-delayable treatment necessary. Open surgery has been the traditional treatment; however, this approach is associated with a high perioperative mortality rate of up to 60% in the paravisceral aorta [6]. Endovascular aneurysm repair (EVAR) of IAAs, combined with prolonged antibiotic treatment, is a less invasive alternative that has gained popularity in recent years due to its association with improved short- and long-term survival compared with open repair [7].

IAAs involving the visceral arteries pose greater surgical challenges than infrarenal IAAs due to the need to preserve visceral artery perfusion. In these cases, endovascular treatment is complex, as the diseased aorta must be covered with a stent graft while simultaneously preserving blood flow to the visceral arteries. Fenestrated or branched EVAR are valid options; however, they have the disadvantage of requiring long manufacturing times.

EVAR of IAAs using parallel stent grafting (PG) technique has been infrequently described in the literature [1,3,8]. Here, we describe our experience with PG technique for the treatment of suprarenal IAAs involving the visceral arteries and present a review of the literature. The Institutional Review Board approval was waived due to the retrospective nature of this technical note. Consent was obtained from the patients for the publication of this technical note, and the principles of the Helsinki Declaration were followed.

1) Patient 1

A 75-year-old male smoker with cardiovascular risk factors and a history of cellulitis in the left arm two months prior presented to the emergency department (ED) with abdominal pain persisting for two weeks. He had visited the ED three times in the previous week, and computed tomography angiography (CTA) showed no evidence of abdominal pathology (Fig. 1). He was discharged with analgesics.

Figure 1. Computer tomography scan showed no evidence of abdominal vascular pathology. (A) Sagittal view. (B) Axial view. The arrows showed the absence of aneurysm at the level of the celiac trunk ostium.

Six days later, the patient was readmitted with diffuse abdominal pain but no peritoneal irritation on physical examination.

Laboratory tests showed leukocytosis (16.81×10³/µL, 77.5% neutrophils) and elevated C-reactive protein (CRP, 264 mg/L; normal: 0-8 mg/L). Other parameters were within normal ranges.

Given the persistence of the abdominal pain and poor response to analgesic treatment with opioids, a repeat CTA was performed. The scan revealed a newly developed 28.0×20.0 mm saccular aneurysm at the level of the celiac trunk (CT) ostium with a peri-aortic collection and CT occlusion at its origin (Fig. 2). A concomitant alveolar lesion suggested pneumonia. These findings indicated an infected aneurysm with probable contained rupture.

Figure 2. Computed tomography angiography revealed a saccular aneurysm at the level of the celiac trunk (CT) ostium with a peri-aortic collection. (A) Sagittal view. (B) Axial view. (C) Schematic drawing of the parallel grafts technique for ensuring the superior mesenteric artery patency and coil embolization of the aneurysmal sac is shown in panel. The arrows show a saccular aneurysm at the level of the CT ostium with peri-aortic collection.

The diagnosis of IAA was based on a combination of clinical, laboratory, and radiological findings, including rapid growth within one week. Blood cultures were drawn, and empiric antibiotic therapy with daptomycin and piperacilin-tazobactam was initiated one day before surgery. Given the symptomatic, rapid growing aneurysm with signs of contained rupture, surgery was not delayed.

A multidisciplinary discussion with the infectious diseases and anesthesia departments favored EVAR over open surgery due to the aneurysm’s location and high surgical risk.

Aortic angiography confirmed the presence of the aneurysm on the anterior aorta, involving the CT ostium. Therefore, performing only CT embolization was not considered, because complete exclusion of IAA required sealing the diseased aorta between healthy landing zones. The initial plan was to place stents in the superior mesenteric artery (SMA) and CT. However, the CT was occluded at its origin, precluding catheterization and antegrade flow preservation. The SMA was catheterized via the left axillary access, an 8-French 70 cm sheath (Flexor Ansel Guiding Sheath, Cook Medical) was placed, and an 8×150 mm Viabahn Endoprosthesis (W. L. Gore & Associates) was introduced. The aneurysm was accessed via the left femoral artery, and a mammary catheter was left in the sac prior to the introduction and deployment of the thoracic aortic stent graft.

The C-TAG (Gore Medical; 34×100 mm) thoracic stent graft was positioned via the right femoral access, with partial deployment above the renal arteries, excluding the aneurysm. Proximal and distal sealing was achieved within a healthy aorta of at least 2 cm (i.e., a sealing distance of >2 cm between the SMA and renal arteries that ensured an adequate sealing area). Subsequently, the Viabahn Endoprosthesis was deployed in the SMA and reinforced internally with an 8×100 mm Absolute Pro self-expanding stent (Abbott Cardiovascular), and the aortic stent graft was fully deployed (Fig. 3A). The aortic segment of the Viabahn Endoprosthesis was reinforced with a self-expanding stent to increase radial force and subsequently reduce the risk of compression between the aortic endograft and aortic wall. Aortic endograft oversizing was approximately 30% to reduce the risk of gutter endoleak, while SMA stent oversizing was avoided.

Figure 3. Intraoperative angiography (A) demonstrated deployment of all stent grafts, coverage of the celiac trunk, and catheterization of the aneurysmal sac. In the final angiography (B), the arrows showed the patency of the visceral branches and coil embolization of the aneurysmal sac. In the follow-up computed tomography angiography (C), the arrow confirmed the patency of the endovascular treatment.

Completion angiography confirmed patency of the renal arteries, SMA, and CT (via collateral circulation) but detected a type II endoleak through thoracic branches (probably the intercostal arteries) with filling of the aneurysmal sac. The aneurysm sac was embolized with Azur coils (Terumo Medical Corp.) via a Progreat microcatheter (Terumo Medical Corp.) introduced through the previously positioned mammary catheter. Final angiography confirmed aneurysm exclusion, no visible endoleak, and preserved visceral artery patency (Fig. 3B).

Intraoperative blood samples taken directly from the aneurysm tested positive for methicillin-sensitive Staphylococcus aureus (MSSA), prompting a switch to cloxacillin and daptomycin for 29 days. Echocardiography ruled out endocarditis, and the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) polymerase chain reaction (PCR) test was negative.

Postoperatively, the patient developed abdominal pain in the right hypochondrium and a worsening general condition. Abdominal ultrasonography showed findings suggestive of acute cholecystitis, prompting the general surgery department to recommend urgent surgery. Intraoperatively, the patient was diagnosed with acute cholecystitis and right colon ischemia, requiring cholecystectomy and right colectomy with terminal ileostomy. No preoperative imaging confirmed intestinal ischemia and the diagnosis was made intraoperatively. Postoperative CT showed distal SMA thrombosis, though visualization was limited by poor image contrast. The patient gradually improved, with resolving abdominal pain, negative blood cultures, and normalized inflammatory markers. He was discharged on postoperative day 29 with chronic oral levofloxacin (500 mg/day).

At 35 months, the patient remained asymptomatic on oral levofloxacin. Follow-up positron emission tomography-computed tomography (PET-CT) and laboratory tests showed remission of the infection. CTA performed 34 months after surgery confirmed the patency of stent grafts, complete exclusion of the aneurysm, and no endoleak (Fig. 3C).

2) Patient 2

A 76-year-old male smoker with hypertension and a history of orchiepididymitis 1 year prior presented to the ED with lumbar pain of 2 weeks’ duration. Despite visiting the ED three times in the previous week; laboratory tests showed no notable alterations, and he was discharged with analgesic treatment, but symptoms persisted.

Ten days later, he was readmitted to the ED with nonspecific lower back pain. Abdominal physical examination was unremarkable.

On admission, laboratory tests showed leukocytosis (14.89×10³/µL, 87.6% neutrophils) and elevated CRP (299 mg/L). Urinalysis was abnormal, and the subsequent urine culture showed MSSA growth. The remaining laboratory parameters were within normal ranges.

An abdominal CTA revealed a 30.0×18.0 mm saccular aneurysm extending from the CT to the SMA ostium, surrounded by a peri-aortic collection and marked inflammatory changes, suggesting an IAA (Fig. 4). Based on these findings, blood culture, echocardiography, and PET-CT were requested, and empiric antibiotic therapy with cloxacillin and ceftriaxone was initiated. Subsequently, the antibiotic therapy was adjusted to cloxacillin and daptomycin after MSSA growth in the blood culture. Echocardiography ruled out endocarditis, and the SARS-CoV-2 PCR test result was negative. PET-CT showed increased aneurysmal sac size compared to the previous CTA performed 3 days earlier, with a maximum transverse diameter of 71 mm. In addition, significant pathological hypermetabolism indicating infectious pathology was identified in the saccular aneurysm and between the C6 and C7 vertebrae, probably related to spondylodiscitis (Fig. 5A).

Figure 4. Computed tomography angiography revealed a saccular aneurysm extending from the celiac trunk (CT) to superior mesenteric artery ostium, surrounded by a peri-aortic collection with adjacent inflammatory changes. (A) Sagittal view. (B) Axial view. Schematic drawing of the parallel grafts technique is shown in panel (C). The arrows showed a saccular aneurysm extending from the CT to superior mesenteric artery ostium.

Figure 5. Positron emission tomography-computed tomography (A), the arrows showed significant pathological hypermetabolism indicating an infectious pathology in the saccular aortic aneurysm and foci between C6 and C7. Final angiography (B), the arrow showed aneurysm exclusion without endoleaks, patency of visceral branches. Follow-up computed tomography angiography (C), the arrow showed demonstrated a suspicious type III endoleak.

A multidisciplinary discussion recommended endovascular treatment due to the high morbidity and mortality associated with open surgery.

Initial angiography confirmed the aneurysm’s extension from the CT to SMA. A 9×150 mm Viabahn Endoprosthesis was placed in the SMA via the left axillary access, and 9×100 mm and 9×50 mm Viabahn Endoprosthesis were placed distally and proximally, respectively, in the CT, using the right axillary access. Because only one 150 mm long Viabahn Endoprosthesis was available and already placed in the SMA, two Viabahn Endoprosthesis were used in the CT due to the length concern. A thoracic aortic stent graft (C-TAG, Gore Medical; 37×100 mm) was positioned via the right femoral access and partially deployed above the renal arteries. Subsequently, Viabahn Endoprosthesis were deployed in the SMA and CT and internally reinforced with 9×100 mm and 9×60 mm Absolute Pro Self-Expanding Stents, respectively. Finally, the thoracic endograft was fully deployed. Oversizing of the aortic stent graft was performed, as in the previous case, while no oversizing was done for the visceral branches.

The final angiography showed exclusion of the aneurysm without endoleaks and patency of the SMA and CT stents (Fig. 5B). Intraoperative blood cultures showed MSSA growth.

Postoperative recovery was favorable with resolution of back pain, negative blood culture, and normalization of laboratory parameters, and the patient was discharged on postoperative day 15 with chronic oral antibiotic therapy (500 mg levofloxacin).

However, three days after discharge, the patient returned with abdominal discomfort and nausea. Follow-up abdominal CTA revealed findings suspicious for type III endoleak (Fig. 5C). Selective angiography for the CT and SMA showed no visible endoleaks. However, the aortic angiography via the left femoral artery showed contrast extravasation compatible with a type IB endoleak (Fig. 6A). Balloon angioplasty (Reliant Stent Graft Balloon Catheter, Medtronic) of the thoracic endoprosthesis with simultaneous balloon protection of the CT and SMA was performed (Fig. 6B); however, the endoleak persisted in the distal part of the thoracic endograft. Therefore, the distal seal was extended to the infrarenal aorta using two aortic endoprostheses (C-TAG, Gore Medical; 28×100 mm and 34×100 mm) and balloon-expandable stent grafts (Viabahn VBX Balloon Expandable Endoprosthesis, Gore Medical; 6×79 mm and 7×79 mm) in the right and left renal arteries, respectively. Two aortic endoprostheses were used to address the diameter difference between the suprarenal and infrarenal aortas. A 28 mm aortic endoprosthesis was placed distally with sealing below the renal arteries, and a 34 mm endoprosthesis was placed proximally to overlap the previous 37 mm endoprosthesis, compensating for the diameter discrepancy. Balloon-expandable VBX stents were used in the renal arteries due to their higher radial force and resistance to compression compared to self-expanding stents.

Figure 6. (A) In the angiography, the arrows showed contrast leakage consistent with a type IB endoleak. (B) Remodeling angioplasty of the thoracic endoprosthesis with simultaneous balloon protection of the celiac and superior mesenteric arteries. (C) Final angiography confirmed the resolution of the type IB endoleak and patency of the endovascular treatment.

After stent graft extension, angiography showed resolution of the type IB endoleak (Fig. 6C), but a small contrast extravasation was visible in the late phase at the posterior aspect of the descending thoracic aorta, consistent with a type II endoleak, which was managed with follow-up CTA for monitoring.

Following the second operation, the patient showed favorable clinical progress, with resolution of abdominal pain, and was discharged on the tenth postoperative day with oral levofloxacin.

During follow-up, the patient remained asymptomatic with no signs of infection. However, follow-up CTA revealed aneurysmal sac growth related to a type II endoleak. At 24 months, diagnostic angiography was performed to address the endoleak. Selective SMA and CT angiographies through the left brachial access showed no endoleak. However, aortic angiography revealed filling of the aneurysmal sac via two intercostal arteries. Catheterization of the aneurysmal sac was performed through the space between the aortic endograft and the aortic wall. The correct position was confirmed, and multiple Azur coils were deployed in the sac. Final angiography showed no filling of the sac and patency of the CT and SMA.

At 33 months of follow-up after the initial intervention, the patient remained asymptomatic on oral levofloxacin. The laboratory findings and follow-up PET-CT showed remission of the infection. The abdominal CTA confirmed aneurysm exclusion without endoleaks. However, asymptomatic SMA stent thrombosis was observed, with distal SMA flow maintained through collateral branches, so no further intervention was needed (Fig. 7).

Figure 7. In the computed tomography angiography at last follow-up, the arrows showed thrombosis of the superior mesenteric artery stent, with stent patency of the celiac and both renal arteries.

Infected aortic aneurysm (IAA) is a complex diagnostic and therapeutic condition. Risk factors include prior infections, arterial injury, and impaired immunity [4]. Both of our cases had active infections at the time of IAA diagnosis: pneumonia in the first case and urinary tract infection in the second case. This suggests that hematogenous dissemination is the likely cause of IAA formation in these cases.

IAA should be considered in patients with fever, abdominal or back pain, or a pulsatile abdominal mass. Inflammatory markers and leukocyte levels are frequently elevated, and 50%-85% of cases have positive blood cultures. In addition, characteristic CT findings contribute to the diagnosis [5,9,10].

Management of IAAs remains controversial with no consensus on the treatment or follow-up [1-4]. Early surgical treatment is commonly combined with prolonged antibiotic therapy, regardless of the IAA’s size or location [5,9,10]. While broad-spectrum antibiotics are often initiated empirically, the optimal duration or choice of antibiotics do not have clear consensus [3,5]. The European Society for Vascular Surgery guidelines recommend starting empirical therapy against Staphylococcus aureus and gram-negative rods, adjusting the regimen based on the microbiological results or continuing empiric treatment if blood and tissue cultures are negative [9]. The antibiotic regimen should be formulated on a case-by-case basis in close collaboration with microbiology and infection specialists, based on clinical, laboratory, and imaging findings. Surveillance and the duration of antibiotic therapy (ranging from 4-6 weeks to lifelong) are influenced by the identified organism, type of surgery, and patient’s Immune status [9]. Exclusive antibiotic therapy is not recommended for IAAs, as it has been linked to high in-hospital mortality rates (75% to 100%), with aneurysm rupture being the primary cause of death [2,5].

EVAR is becoming increasingly popular for complex aortic aneurysms, including those involving the visceral branches of aorta. However, the use of endoprosthesis in infected area remains controversial due to the persistence of infected tissue, which could increase the risk of subsequent endoprosthesis infection [3]. Some studies have proposed favorable outcomes with delayed surgery, after antibiotics have controlled the infection in hemodynamically stable patients, with the goal of eradicating bacteria before deploying a stent graft. However, due to the high risk of aneurysm growth and rupture in IAAs, delaying surgery remains a significant concern [9]. In our cases, both patients required non-delayable surgeries. Antibiotic therapy was started one day before surgery in the first case and three days before in the second; however, long-term antibiotics were administered post-surgery. Due to the rarity of IAA, its anatomical complexity and bacteriology, as well as the lack of strong evidence, firm recommendations cannot be made, and an individualized approach remains essential.

A recent Swedish multicenter study analyzing 132 cases showed higher early survival rates with endovascular treatment of infected aortic pathologies compared to open surgery (3-month survival: 96% vs. 74%, P<0.001 and 1-year survival: 84% vs. 73%, P=0.054), with no increased risk of reinfection or reintervention [8,11]. This study highlighted a clear paradigm shift toward EVAR for treating IAAs over the last two decades.

Surgery for paravisceral IAAs is more complex than infrarenal surgery, as it requires the preservation of visceral artery perfusion, with a reported perioperative mortality rate of up to 60% for open surgery [12].

Few cases of endovascular treatment of IAAs involving the paravisceral aorta have been reported. As these clinical situations frequently require urgent treatment, waiting for a fenestrated or branched endograft is often not an option [1,8]. Surgeon-modified EVARs using fenestrated and branched stent grafts have been described in a small case series of IIA patients. Juszczak et al. [13] reported a 30-day in-hospital mortality rate of 16.7% in 28 IAA patients. Given the complexity of these procedures, the authors concluded that they should be performed in high-volume, specialized aortic centers. As our institution lacked experience with this technique, we excluded it as a treatment option.

The use of PG technique in the treatment of IAAs appears to be a valid option, as described in the literature on paravisceral aneurysms [1,3,8]. This allows coverage of the diseased aorta while preserving flow to the visceral vessels. Furthermore, the necessary devices are more readily available in centers performing EVAR, making PG a feasible option in urgent cases [1,8]. A potential disadvantage of PG is for the risk of endoleaks, with Tanious et al. [14] observing that the likelihood of endoleaks increases with the number of stents placed. To minimize the risk of endoleaks, it is preferable to place no more than two PGs in one direction. Stent graft oversizing of 30% is also recommended to reduce the risk of a gutter endoleaks [15]. In our cases, stent graft oversizing of approximately 30% was performed, and no gutter endoleaks were observed in both cases.

Several studies have reported the use of chimney or periscope grafts for paravisceral IAAs. Silverberg et al. [8] found no intraoperative complications, a perioperative mortality rate of 12%, and no endoleaks or reinterventions at the 8-month follow-up in 8 IAA patients treated with chimney EVAR. Zemela et al. [3] described a case of IAA treated with EVAR using downward-facing snorkel and upward-facing periscope grafts placed parallel to the main body graft, with no complications at 4 years. Similarly, Xodo et al. [1] described the use of multiple PGs with a quadruple chimney/periscope configuration combined with thoracic endograft deployment for the urgent treatment of a ruptured IAA and reported no endoleak or infection, with continued patency at the 6-month follow-up.

In our cases, although the Viabahn Endoprosthesis were internally reinforced with a self-expanding stent to increase radial force and reduce the risk of stent compression, one patient developed asymptomatic SMA stent thrombosis on follow-up. Although there is no manufacturer recommendation for this off-label technique, studies have examined this approach to enhance the resistance of the parallel stent to the compression between the aortic endograft and aortic wall [15]. In our patient, the SMA stent thrombosis was asymptomatic without clinical consequences, and distal flow was preserved through the collateral branches.

In our experience, the PG technique together with prolonged antibiotic therapy is a feasible option for managing paravisceral IAAs, preserving visceral artery patency, and achieving remission of infection at follow-up. The necessary devices are readily available in centers performing EVAR, making them suitable for urgent situations. However, long-term follow-up is needed to assess the durability and possible late infection-related complications.

None.

The authors have nothing to disclose.

Concept and design: IFA, JFL. Analysis and interpretation: IFA. Data collection: IFA. Writing the article: IFA, JFL. Critical revision of the article: IFA, JFL. Final approval of the article: all authors. Statistical analysis: none. Obtained funding: none. Overall responsibility: IFA.