Can an accessory renal artery be safely covered during endovascular aortic aneurysm repair?

Abstract

A best evidence topic was constructed according to a structured protocol. The question addressed was whether coverage of an accessory renal artery (ARA) in patients undergoing endovascular aortic aneurysm repair (EVAR) is associated with increased risk of renal impairment. Altogether, 106 papers were located using the reported searches, of which 5 represented the best evidence to answer the question. The authors, journal, date and country of publication, study type, patient group studied, relevant outcomes parameters and results of these papers are tabulated. Our best evidence analysis included 116 patients who had one or more ARA excluded during EVAR. Segmental renal infarction occurred in varying numbers of patients (ranging from 0 to 84%). The authors consistently demonstrate that loss of renal mass is not associated with functional renal impairment, expressed by various outcome parameters such as serum creatinine, glomerular filtration rate (GFR), renal failure requiring dialysis and worsening hypertension. Comparisons of groups of patient with covered or preserved ARAs by one of the selected studies showed no difference in any of these renal outcome parameters, apart from a significantly higher renal infarct volume in the former group (P < 0.001). Subgroup analysis of patients with pre-existing renal dysfunction (GFR < 60 ml/h/m²) showed no difference in GFR change when comparing covered with uncovered ARA patient cohorts. No type II endoleak related to the covered ARA was reported in any of these studies. In conclusion, current evidence supports the safety of coverage of ARAs located in the proximal fixation zone to achieve seal in EVAR.

INTRODUCTION

A best evidence topic was constructed according to a structured protocol. This protocol has been previously fully described [1].

THREE-PART QUESTION

In [patients undergoing endovascular aortic aneurysm repair (EVAR)], is [coverage of an accessory renal artery (ARA) with the aortic endograft] associated with [increased risk of renal impairment]?

CLINICAL SCENARIO

You attend a multidisciplinary meeting to discuss the management of a 77-year old male patient with a 6.8 cm abdominal aortic aneurysm. His American Society of Anaesthesiologists (ASA) score is III. The origin of his right main renal artery has a 40% stenosis, and the left renal artery is widely patent. A right ARA coming off the aorta 6 mm below the main renal artery is evident on computer tomography angiography (CTA). The serum creatinine level is 1.4 mg/dl. The neck anatomy is friendly for an EVAR, if the ARA is covered; however, preservation of the ARA creates a short proximal neck (7 mm).

SEARCH STRATEGY

Medline was searched using the PubMed interface from 1948 to March 2013: [accessory renal artery] AND [endovascular procedures (MeSH terms)] OR [aortic aneurysm (MeSH terms)] OR [occlusion] OR [coverage]. Related articles and references were screened for suitable articles.

SEARCH OUTCOME

One hundred and six papers were found using the reported search. Five of these articles provided best evidence to answer the question [2–6]. These are presented in Table 1.

Table 1:

Best evidence papers

Author, date, journal and country Study type (level of evidence)	Patient group	Outcomes	Key results	Comments
Greenberg et al. (2012), J Vasc Surg, USA [2] Retrospective cohort study (level 3)	40 patients had 45 ARAs covered during EVAR 29 patients had uncovered ARAs during EVAR (No differences in demographic/clinical characteristics) (No differences in anatomic characteristics, suprarenal vs infrarenal fixation—covered group had shorter neck length) Renal infarction volume calculated using the disk-summation method	30-day mortality Survival at 24 m Endoleak Secondary interventions Change in GFR Change in antihypertensive medications Renal infarction volume	No difference in: P = 1.0 P = 0.1861 P = 0.45 P = 1.0 P = 0.4 P = 0.6069 Significant difference in renal infarct volume (P < 0.0001)	Renal mass is commonly lost, but renal function is maintained after ARA coverage No difference in ARA-related endoleaks ARA size, pre-existing renal insufficiency or hypertension did not influence outcomes
Dzieciuchowicz et al. (2012), Ann Vasc Surg, Spain [3] Prospective case series (level 3)	6 patients had ARAs covered during EVAR None of the patients had estimated GFR <60 ml/min/m2 Renal scintigraphy pre- and postoperatively to determine % value of lost renal mass	Serum creatinine Lost renal mass	Transient increase in serum creatinine in all but 1 patient (values reverted to baseline levels 30/90 days postintervention) Mean lost renal mass: 18.4% (range 9.6–22.5%)	Intentional coverage of ARAs during EVAR is safe in patients with no pre-existing renal disease
Karmacharya et al. (2006), J Vasc Surg, USA [4] Retrospective cohort study (level 3)	35 patients had ARAs covered during EVAR Type of aortic endograft device: AneuRx: 10; Talent: 7; Powerlink: 7; Zenith: 5; Lifepath: 4; Ancure: 2 Followed up with high resolution CTA	Mortality ARA-related endoleak Renal infarcts Hypertensive status Serum creatinine Creatinine clearance	No mortality No ARA-related endoleak 7 renal infarcts (20%) No change in hypertensive status No difference between pre- and postoperative serum creatinine No difference between pre- and postoperative creatinine clearance	Coverage of ARAs during EVAR is not associated with renal impairment, even in patients with documented renal infarction No ARA-related endoleak was demonstrated
Kim et al. (2004), Ann Vasc Surg, USA [5] Retrospective cohort study (level 3)	11 patients had 12 ARAs covered during EVAR 8 patients had uncovered ARAs (located in the infrarenal neck) during EVAR All treated with the AneuRx device	Serum creatinine Renal failure Change in blood pressure Renal infarcts Type I endoleak Type II endoleak	No difference in serum creatinine between covered and uncovered groups (P = 0.90) No patient in the covered group developed renal failure No patient in the covered group developed change in blood pressure No patient in the covered group had renal infarcts Type I endoleak: covered vs uncovered group, 0 vs 38% Type II endoleak: covered vs uncovered group, 36 vs 13% (no ARA-related endoleak)	Complications resulting from covering ARAs are minimal in patients with normal renal function It is prudent to cover ARAs to obtain proximal seal
Aquino et al. (2001), J Vasc Surg, USA [6] Cohort study (level 3)	24 patients had 26 ARAs covered during EVAR Patients with serum creatinine > 2 mg/dl did not have ARA coverage Ancure device in 23 patients, Excluder device in 1 patient Mean follow-up 11.5 months	Renal infarcts Hypertensive status Renal failure Endoleak Mortality	5 renal infarcts (21%) 1 patient developed hypertension postoperatively 1 patient developed renal failure No ARA-related endoleak 1 patient died during follow-up (cardiac event)	Complications from exclusion of ARAs during EVAR are uncommon and mild

RESULTS

Greenberg et al. [2] conducted a retrospective cohort study comparing outcomes of EVAR with and without ARA coverage. Forty patients having 45 ARAs covered during EVAR were compared with 29 patients who had intentional ARA preservation. No significant differences in clinical and anatomic characteristics between the two groups were identified, except that patients with covered ARA had shorter proximal neck (P = 0.03). Suprarenal fixation was used in just over half of the patients in each group, and the amount of contrast used was similar in the two groups. Thirty-day and 24-month mortality and the incidence of secondary interventions and ARA-related endoleak were not different in patients with covered and uncovered ARAs. There was no significant deterioration in glomerular filtration rate (GFR) in the study group compared with the control group, and the requirements for antihypertensive medications were similar. On the contrary, the volume of renal infarction was higher in patients with covered ARA (12.1 vs 0.5%, P < 0.0001). No association was found between GFR deterioration and increasing ASA size that was covered.

Dzieciuchowicz et al. [3] prospectively recorded the renal function of 6 patients who had intentional ARA coverage during EVAR. None of the patients had pre-existing renal dysfunction (GFR < 60 ml/min/m²). A rise in serum creatinine concentration was found in all but 1 patient between 24 and 72 h postintervention, which reverted to the baseline levels 30 days later. The mean value of lost renal mass was 18.4% (9.6–22.5%) as determined by renal scintigraphy.

Karmacharya et al. [4] performed a retrospective review of 35 consecutive patients who had their ARAs sacrificed during EVAR. No mortality was noticed. Twelve endoleaks were documented in follow-up, but none of them was related with an ARA. Renal infarction was demonstrated in 7 patients (20%) on follow-up CTA. Hypertensive status did not change in any patient in whom an ARA had been covered. No significant difference between preoperative and postoperative serum creatinine and creatinine clearance was found. The authors also concluded that even when segmental renal infarction occurred, it was well tolerated without clinical consequences or laboratory changes. Twenty-six patients without ARAs who underwent EVAR served as the control group, and no difference in the aforementioned outcome parameters was observed.

Kim et al. [5] compared the outcomes of EVAR in 11 patients with covered and 8 patients with uncovered ARAs. As expected, infrarenal neck length was shorter in the uncovered group. Postoperative serum creatinine was not different in the two groups. None of the patients who had the ARA covered during EVAR developed acute renal failure requiring dialysis, or change in blood pressure control. Furthermore, CT demonstrated no segmental renal infarctions in any of these patients. No endoleak related to the excluded ARA was noted in the follow-up period. Three of the patients who had the ARA preserved developed a proximal type I endoleak requiring secondary procedures, whereas none of the patients who had their ARA covered developed such endoleak. The authors concluded that exclusion of ARAs during EVAR has minimal consequences in patients with normal renal function. They went as far as suggesting that ARAs should be covered to obtain adequate proximal seal.

Aquino et al. [6] reviewed the records of 37 patients with 52 ARAs who were considered for EVAR. Of these, the outcomes of 24 patients who had 26 ARAs excluded to facilitate EVAR were analysed. The size of the vessel in relation to the main renal artery and the absence of renal disease were considered before the ARA was sacrificed. Segmental infarction of the renal parenchyma was demonstrated on follow-up CTA in 6 patients (21%). One patient developed transient hypertension postoperatively, which required adjustment of the antihypertensive treatment. Serum creatinine levels remained unchanged in all but 1 patient, who developed progressive renal failure requiring dialysis. Renal flow scan revealed normal renal parenchyma perfusion, suggesting aetiology not related with the coverage of the ARA. None of the patients developed type II endoleak related with the ARA. However, a single patient had a type Ib endoleak, with the ARA originating from the aneurysm sac acting as the outflow vessel. This was successfully treated with coil embolization.

CLINICAL BOTTOM LINE

Infrarenal neck length is a significant anatomic parameter determining the suitability for EVAR. Commonly, clinicians face the dilemma whether one or more ARAs located in the proximal fixation zone should be covered to achieve seal. Current evidence supports the safety of ARA coverage during EVAR when necessary. Even though segmental renal infarction may occur in a considerable number of patients as a result of ARA exclusion, it does not seem to be associated with adverse clinical effects, such as renal failure and change in hypertensive status. The wide range of segmental renal infarction found in the reported studies may be explained by the different diagnostic methods used to assess its presence and extent, including CTA, renal scintigraphy and volumetric analysis of three-dimensional reconstructions of CT scans. Uncertainty exists regarding the impact of ARA coverage on pre-existing renal impairment. Subgroup analysis of patients with chronic renal impairment performed by Greenberg et al. [2] revealed no differences in renal function when comparing patients with ARA coverage and ARA preservation. The risk of type II endoleak originating from an excluded ARA is negligible.

Conflict of interest: none declared.