Outcomes of open and endovascular repair of inflammatory abdominal aortic aneurysms

Abstract

Objective

Reports on inflammatory aortic abdominal aneurysm treatment are scarce. Traditionally, open surgery has been validated as the gold standard of treatment; however, high technical skills are required. Endovascular aortic repair has been suggested as a less invasive treatment by some authors offering good results. The purpose of our study was to report our experience and outcomes in the treatment of inflammatory aortic abdominal aneurysm using both approaches.

Material and methods

A retrospective review and data collection of all patients treated for inflammatory aortic abdominal aneurysm between 2000 and 2015 was done in one academic center. Diagnosis of inflammatory aortic abdominal aneurysm was based on preoperative CT-scan imaging. Type of treatment, postoperative and long-term morbidity and mortality are described. Abdominal compressive symptoms (hydronephrosis) severity and relief after treatment are described.

Results

Thirty-four patients with intact inflammatory aortic abdominal aneurysm were included. Twenty-nine (85.3%) patients were treated by open means and the remaining five (14.7%) with endovascular aortic repair. Nearly 90% were considered high-risk patients. Median follow-up was 46 months (range 24–112). The two groups were comparable, except for the age and preoperative hydronephrosis. There was no statistical significance in blood transfusion requirements, intensive care hospitalization, 30-day and long-term mortality between the two groups. Preoperative hydronephrosis was diagnosed in four (13.8%) patients in the open surgery group and three (60%) patients in the endovascular aortic repair group. Improvement of hydronephrosis was recognized in three out of the four patients in the open repair group and two out of the three in the endovascular aortic repair group. Renal function remained stable in both groups during follow-up.

Conclusions

Open surgery remains a safe and valid option for the treatment of inflammatory aortic abdominal aneurysm. Although our study included a small number of patients with endovascular aortic repair treatment, results are promising. Further randomized controlled studies may be necessary to assess long-term effectiveness of endovascular aortic repair treatment in this disease.

Keywords

Abdominal aortic aneurysm inflammation endovascular procedures surgery

Introduction

Inflammatory abdominal aortic aneurysm (IAAA) is defined as presence of the triad of: a whited and thickened aneurysm wall, retroperitoneal fibrosis, and involvement of adjacent structures such as ureter, duodenum, inferior vena cava, and iliac veins.^1,2

IAAA are a minor group of abdominal aortic aneurysm (AAA). Its incidence ranges from 2.2 to 18% of the total number of AAAs.^1,2 The etiology is still unknown. Patients are usually younger, male, and with previous history of tobacco use.^2,3

In 1935, James⁴ first reported a case of a patient with AAA and retroperitoneal fibrosis with uremia secondary to ureteral involvement. Afterward, Walker et al.⁵ described the first morphological definition of IAAA in a series of 19 patients with this entity.

The most common clinical features of inflammatory aneurysms are represented by symptoms, such as abdominal or back pain, fever, and obstructive uropathy (found in nearly 25% of patients). Entrapment of organs can develop compression of the ureter and the duodenum, with consequences like uretero-hydronephrosis and bowel obstruction.

Preoperative diagnosis is possible by abdominal ultrasonography. Angio-CT (computed tomography) allows specific diagnosis by the typical image of soft tissue surrounding the aortic wall enhanced (“mantle sign”) and identifies possible entrapment of surroundings organs.

Open surgery repair (OSR) has traditionally been the gold standard of treatment. This approach is associated to a high morbidity and mortality, though. High skills in open surgery are required due to the difficulty in the technique.^2,6 Endovascular aortic repair (EVAR) is being widely used for AAA treatment with good early results. However, the survival benefit with EVAR seems to be lost in the midterm. Some previous reports have suggested EVAR as a less invasive treatment for inflammatory aneurysms with less morbidity and mortality.^2,6

The aim of this study is to describe our postoperative and long-term institutional outcomes in the treatment of IAAA with both, open surgery and endovascular repair over a 15-year period.

Material and methods

We retrospectively reviewed all patients with nonruptured IAAA treated in a single center from January 2000 to December 2015.

The inclusion criteria were elective cases with inflammatory signs surrounding the aneurysm in the angio-CT scan, such as thickened aneurysm wall and adhesions to surrounding organs (Figure 1). We excluded patients treated in the urgent setting and with infectious origin.

Figure 1.

Axial CT images showing inflammatory aneurysms. Thick arrow: peri-aneurysmal fibrosis. Thin arrow: left kidney hydronephrosis.

Figure 2 shows our center protocol once the diagnosis of IAAA is made. Those patients with ureteral obstruction were preoperative evaluated by an urologist at our institution. Patients were divided into two groups according to the type of treatment received, OSR and EVAR. Surgical decision was made on patient’s comorbidities, anatomical endovascular suitability, and the expertise of the surgeon. Urological assessment in patients with ureteral obstruction did not interact with the type of vascular treatment required. We performed femoral cutdown in all patients in the EVAR group.

Figure 2.

Our protocol after the diagnosis of an inflammatory abdominal aortic aneurysm.

For the purpose of this study we analyzed: Basic demographics such as age, sex, active smoker, cardiovascular risk factors, coronary artery disease, preoperative chronic renal dysfunction, and preoperative hydronephrosis; preoperative symptoms related to the IAAA and outcomes of the study; transfused red blood cell units, intensive care unit hospitalization, overall time hospitalization, 30-day morbidity and mortality, overall mortality, hydronephrosis treatment, postoperative hydronephrosis, and renal function.

We performed a clinical and radiological follow-up. The first follow-up visit was performed at three months after the operation. Patients underwent clinical examination by vascular surgeons and abdominal ultrasound examination at that time, and then annually thereafter.

Definitions

Chronic renal failure: glomerular filtration rate <60 ml/min.

Hydronephrosis: dilatation of the renal pelvis and calyces caused by an obstruction of the free flow of the urine from the kidney.

Technical success: completion of the open surgery or endovascular treatment of the inflammatory AAA.

Statistics

All data were analyzed with Stata® (version 12, for Mac). Results were reported as median and range for continuous variables, and proportions (%) for discrete ones. Differences between the two groups were analyzed by Chi-squared test for discrete variables test and by Student’s t or Mann–Whitney test for continuous variables. The overall survival during the follow-up was evaluated with the Kaplan–Meier curves.

Results

For the 15-year study period, 34 patients underwent repair of an intact IAAA and were included in the study. Twenty-nine were treated by open means and the remaining five, with EVAR.

Basic demographics of the series are shown in Table 1. Median age at the moment of treatment was 71.5 (63.8–72.2) years, being 79 (72.5–82.5) years in the EVAR group and 70 (63–75) years in the OSR group (p = 0.016). Thirty-three (97%) patients were male, 30 (91%) were smokers, and 30 (88%) were classified as high risk (ASA III and IV). Twenty percent (seven patients) of the whole series had preoperative hydronephrosis and chronic renal dysfunction. Preoperative hydronephrosis was diagnosed in four (13.8%) patients in the open surgery group and three (60%) patients in the EVAR group (p = 0.046). Both groups were comparable in terms of basic demographics and comorbidities, except for a statistically older population (p = 0.016) and more preoperative hydronephrosis (p = 0.046) in the EVAR group.

Table 1.

Basic demographics characteristics of patients with inflammatory abdominal aortic aneurysms in both endovascular and open surgery groups, and the whole cohort.

	EVAR (N = 5)	Open surgery (N = 29)	p	All patients (N = 34)
Median age (years)	79 (72.5–82.5)	70 (63–75)	0.016	71.5 (63.8–72.2)
Gender (male)	4 (80%)	29 (100%)	0.14	33 (97%)
Smoking	4 (80%)	27 (96.4%)	0.38	31 (91.2%)
Hypertension	3 (60%)	17 (60.7%)	0.87	20 (58.8%)
Diabetes mellitus	1 (20%)	4 (14.3%)	0.57	5 (14.7%)
Coronary artery disease	2 (40%)	9 (32.1%)	0.53	11(32.4%)
Preoperative hydronephrosis	3 (60%)	4 (13.8%)	0.048	7 (20.6%)
CRF (GFR<60 mmHg)	1 (20%)	6 (20.7%)	0.57	7 (20.6%)
Symptomatic	3 (60%)	8 (28.6%)	0.67	11 (32.4%)
ASA ≥ III	4 (80%)	26 (89.7%)	0.49	30 (88.2%)
Iliac aneurysm	1 (20%)	7 (24.14%)	0.67	8 (23.5%)
Aneurysm size (cm)	70 (56–90)	60 (55–66.5)	0.26	60 (55–70)

ASA: American society of anesthesiologists; CRF: chronic renal failure; EVAR: endovascular aortic repair; GFR: glomerular filtration rate.

The median diameter before treatment was 60 mm (range 55.0–66.5 mm) in the open group and 70 mm (range 56–90 mm) in the EVAR group. Thirty-two percent of patients had preoperative symptoms related to the inflammatory aortic aneurysm, being the most frequent fever and abdominal/lumbar pain, without urgent complications in the angio-CT scan.

The median follow-up for the cohort was 46 months (range 24–112 months). The technical success of both treatments was 100%. Table 2 shows the specific results of each treatment. There was no statistical significance in blood transfusion requirements, intensive care stay, and overall hospitalization between the EVAR and OSR group. There were no early deaths in the EVAR group and one (3.5%) patient registered in the OSR group, p = 0.85. That one patient suffered a massive myocardial infarction at postoperative day 1 in the intensive care unit. We did not found any statistically difference in the 30-day morbidity between the two groups (20% for EVAR versus 10.3% for OSR, p = 0.49). One patient in the EVAR group required massive blood transfusion due to external iliac artery rupture secondary to miss-maneuvers in the endovascular procedure (iliac dissection and perforation) and required an ipsilateral ilio-femoral bypass. This patient complicated with acute renal failure and required intermittent hemodialysis. Three patients in the open surgery group suffered from postoperative complications, two patients with self-limited acute renal failure, and the other one with bowel evisceration that required surgical repair.

Table 2.

Outcomes of endovascular and open repair of inflammatory abdominal aortic aneurysms.

	EVAR (N = 5)	Open surgery (N = 29)	p	All patients (N = 34)
N transfused red blood cell units	0 (0–8)	0 (0–2)	0.53	0 (0–2)
Intensive care days	1 (1–5)	1 (1–1)	0.076	1 (1–1)
hospitalization days	14 (10–26)	11 (8–17.5)	0.421	12 (8–16,75)
Morbidity 30 days	1 (20%)	3 (10.34%)	0.49	4 (11.76%)
Mortality 30 days	0 (0%)	1 (3.45%)	0.85	1 (2.94%)
Overall mortality	1 (20%)	8 (27.59%)	0.60	9 (26.47%)
Treated hydronephrosis	0 (0%)	4 (13.79%)	0.51	4 (11.76%)
Improved hydronephrosis	2/3 (66.67%)	3/4 (75%)	0.71	5/7 (71.43%)
Stable renal function	4/5 (80%)	19/24 (79.17%)	0.72	23/29 (79.31%)

EVAR: endovascular aortic repair.

All patients with hydronephrosis in the OSR group (n = 4) received preoperative ureteral stenting and/or ureterolysis; whereas none of the patients with hydronephrosis in the EVAR group received any urological treatment, p = 0.51. Improvement of hydronephrosis was recognized in three out of the four patients (75%) in the open group and two out of the three (66,7%) in the EVAR group, p = 0.71. Renal function remained stable in both groups during the follow-up.

The overall Kaplan–Meier mortality for the entire cohort was 26.5% (n = 9). The mortality estimated for the EVAR and OSR group was 20% (n = 1) and 27.6% (n = 8), respectively; no statistical difference was found (Figures 3 and 4). None of these deaths were aneurysm related.

Figure 3.

The overall long-term all cohort survival Kaplan–Meier curves.

Figure 4.

The long-term survival Kaplan–Meier curve of the endovascular and open surgery groups.

Discussion

Pathophysiology of IAAA still remains unclear and it has probably a multifactorial origin. Some authors propose that IAAAs and degenerative AAAs have a common origin with varying degrees of inflammation. Common HLA alleles in both degenerative and inflammatory aneurysms have been identified that would support this previous theory.^7–9 Haug et al. demonstrated an autoimmune mechanism related to IAAA. Their case–control study showed a significant difference association of IAAA with autoimmune disease like lupus or rheumatoid arthritis, compared to degenerative ones.^7,10 Some other authors have also suggested a possible infectious etiology secondary to Herpes simplex virus, Cytomegalovirus, Tuberculosis, or Syphilis.^1,7

In our study over 88% of the patients were classified as high risk (ASA≥ III). Only 32% of the whole study group had symptoms (compressive symptoms, lumbar/abdominal pain or fever but intact). We hypothesized that the low incidence of symptomatic patients in our series could be secondary to the exclusion of urgent cases. Kakkos et al. demonstrated in their study the association between the presence of abdominal pain and symptomatic AAA, which required urgent surgery.

Reports on IAAAs treatment are scarce and mainly description of small series. Moreover, reports on EVAR use in this disease are even scarcer.

We mainly describe in this study that there is no difference between OSR and EVAR in terms of postoperative and long-term morbidity and mortality. Prifti et al. reported their experience with the open surgery approach of IAAA with acceptable results. The in-hospital mortality was 5.7%, and five-year mortality was 72%. These outcomes are similar to the ones found in our study. In their series, previous history of myocardial ischemia or renal dysfunction and elevated delta erythrocyte sedimentation rate were strong predictors of poor outcomes during the follow-up.¹ Paravastu et al. published a systematic review comparing the results of OSR and EVAR in IAAA repair. They concluded that there was no difference in terms of 30-day and one-year aneurysm-related mortality. A trend of better hydronephrosis evolution after OSR compared to EVAR was found.¹¹ Some other studies have shown promising results after EVAR in the management of inflammatory aneurysms, with improvement in the aneurysm size, periaortic fibrosis, and hydronephrosis evolution during the follow-up.^12,13 A Cochrane revision was published in 2015 comparing both open and endovascular treatment for IAAA, concluding that high-quality studies are required to evaluate the best treatment for this disease.¹⁴

As EVAR is a less invasive technique than OSR, some authors have demonstrated that it is associated to fewer blood transfusions and shorter hospital stay.⁶ However, we did not find any differences in our series.

Evolution of peri-ureteral fibrosis and renal function after IAAA treatment is still unknown, some studies have reported complete regression of inflammation and others partial regression or persistence of fibrotic process.¹⁵ Additional treatment, such as ureteral stenting, ureterolysis, or pharmacological therapy, can be required in selected cases.^12,16 In our study the incidence of preoperative hydronephrosis and chronic renal dysfunction was 20%, similar to other series found in the literature. We did not found any significant difference between both groups in the evolution of hydronephrosis and renal function in the postoperative period.

Since inflammation is the key component of an IAAA, corticosteroids and immunosuppressive therapies such as methotrexate and azathioprine have been suggested as a treatment option in patients with symptomatic and small inflammatory aneurysms. Some studies have shown improvement of symptoms and degree of periaortic inflammation, although efficacy has not been proved yet.^2,17

Patients undergoing EVAR often develop an inflammatory response called postimplantation syndrome, which is associated to fever and leukocytosis. This should be considered especially in patients where fever is a usual finding, probably showing activity of the disease. It has been demonstrated that this entity is mostly associated to the synthetic polyester textile, compared to the polytetrafluoroethylene endografts.¹⁸ It has been hypothesized that this inflammation after EVAR treatment may interfere in the retroperitoneal fibrosis and hydronephrosis evolution in patients with IAAA.¹²

Despite the similarity of infected and inflammatory AAA, differential diagnosis is mandatory. Mycotic aneurysms are usually associated to a rapid worsening in the clinical condition of the patient with a fatal ending if no treatment is advocated. Angio-CT typical images are aneurysms with saccular form and possibly with air in the aortic wall. In addition, delayed diagnosis and misuse of corticosteroid or immunosuppressing drugs may lead to uncontrolled growth of microorganisms.²

Greatest limitations of our retrospective and nonrandomized study are the small sample of patients, particularly in the EVAR subgroup. In addition, during the early years of the study, open surgery was the only treatment option in our center, which partially explains the asymmetry of patients between the two groups.

Conclusion

Open surgery remains a safe and valid option for the treatment of IAAA in terms of morbidity and mortality with good early and late outcomes. Although our study included a small number of patients with EVAR treatment, results are promising. Further randomized controlled trials may be necessary to assess long-term effectiveness of EVAR treatment in inflammatory AAA. Nevertheless, the rarity of this entity might make this task very difficult to achieve.

Footnotes

Acknowledgment

This article has been presented at the 43rd Veith Symposium, New York. 15–19 November 2016; with title “A 15 year experience with open and endovascular repair for inflammatory aortic abdominal aneurysm.”

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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