Does transrenal fixation of aortic endografts impair renal function?

The effect of Endovascular Aneurysm Repair on Renal Function in Patients Treated for Abdominal Aortic Aneurysm

Aim:

The effect of endovascular aneurysm repair in patients treated for abdominal aortic aneurysm has not been clearly defined. The objective of the present article was to provide a contemporary literature review and perform an analysis to determine the effect of EVAR on renal function in the early post-operative period and during follow-up.

Methods:

A systematic review of the literature was undertaken to identify all studies reporting the effect of EVAR on renal function. Outcome data were pooled and combined overall effect sizes were calculated using fixed or random-effects models.

Results:

Thirty-two studies reporting on 24846 patients were included. Acute renal failure after EVAR occurred with an estimated frequency of 9% (95%CI: 5-16%; I2=97%). Median follow-up period was 19.5 months (range 1-60 months). The estimated frequency of chronic renal failure during follow-up was 7% (95%CI: 3-17%; I2=98%). Hemodialysis was required in 2% (1-3%; I2=97%) of the cases.

Conclusion:

High-level evidence demonstrating the effect of EVAR on the incidence of acute and chronic renal failure is lacking. Based on the current available data, nearly 10% of patients undergoing EVAR for AAA have an increased risk for renal dysfunction after the procedure. Whether this deterioration may lead to a worse outcome has not been adequately proved.

Abdominal aortic aneurysms: pre- and post-procedural imaging

Abdominal aortic aneurysm (AAA) is a relatively common, potentially life-threatening disorder. Rupture of AAA is potentially catastrophic with high mortality. Intervention for AAA is indicated when the aneurysm reaches 5.0-5.5 cm or more, when symptomatic, or when increasing in size > 10 mm/year. AAA can be accurately assessed by cross-sectional imaging including computed tomography angiography and magnetic resonance angiography. Current options for intervention in AAA patients include open surgery and endovascular aneurysm repair (EVAR), with EVAR becoming more prevalent over time. Cross-sectional imaging plays a crucial role in AAA surveillance, pre-procedural assessment, and post-EVAR management. This paper will discuss the current role of imaging in the assessment of AAA patients prior to intervention, in evaluation of procedural complications, and in long-term follow-up of EVAR patients.

Meta-analysis of Renal Function Following Infrarenal EVAR using Suprarenal or Infrarenal Fixation Devices

OBJECTIVE/BACKGROUND

The effect of suprarenal (SR) as opposed to infrarenal (IR) fixation on renal outcomes post-endovascular aneurysm repair (EVAR) remains controversial. This meta-analysis aims to update current understanding of this issue.

METHODS

A prior meta-analysis was updated through a Preferred Reporting Items for Systematic reviews and Meta-Analyses search for additional studies published in the last 3 years reporting on renal dysfunction or related outcomes post-EVAR. Random effects meta-analysis was undertaken using SPSS.

RESULTS

A total of 25 non-randomised studies comparing SR with IR fixation were included, totalling 54,832 patients. In total, 16,634 underwent SR and 38,198 IR. Baseline characteristics, including age, baseline estimated glomerular filtration rate, diabetes, cardiac disease, and smoking, were similar between the groups. There was a small but significant difference in outcomes for renal dysfunction at the study end point (SR 5.98% vs. IR 4.83%; odds ratio [OR] 1.29, 95% confidence interval [CI] 1.18-1.40 [p < .001]); however, at 30 days and 12 months there was no significant difference, and this did not hold up to sensitivity analysis. Incidence of renal infarcts (SR 6.6% vs. IR 2.3%; OR 2.78, 95% CI 1.46-5.29 [p = .002]), renal stenosis (SR 2.4% vs. IR 0.8%; OR 2.89, 95% CI 1.00-8.38 [p = .05]), and renal artery occlusion (SR 2.4% vs. IR 1.2%; OR 2.21, 95% CI 1.15-4.25 [p = 0.02]) favoured IR fixation; however, there was no difference in haemodialysis rates.

CONCLUSION

This meta-analysis has identified small but significantly worse renal outcomes in patients having SR fixation devices compared with IR; however, there was no difference in dialysis rates and a small effect on renal dysfunction, which did not stand up to rigorous sensitivity analysis. This should be taken into consideration during graft selection, and further studies must assess renal outcomes in the longer term, and in those with pre-existing renal dysfunction.

Evaluation of the renal function using serum Cystatin C following open and endovascular aortic aneurysm repair

Objectives

Controversies regarding renal function impairment after open and endovascular aortic aneurysm repair still exist. The purpose of this study was to evaluate the renal function following open repair and endovascular aneurysm repair using Cystatin C.

Methods

This prospective, observational case–control study was conducted in tertiary referral centre over 3 years, starting from 2012. In total, 60 patients operated due to infrarenal AAA either by means of open repair (30 patients) or endovascular aneurysm repair (30 patients) were included in the study. Biochemical markers of renal function (sCr, urea, potassium) were recorded pre-operatively and at these specific time points, immediately after the operation and at discharge, home (third postoperative day, endovascular aneurysm repair group) or from intensive care unit (third postoperative day, open repair group). Multivariate and propensity score adjustments were used to control for the baseline differences between the groups.

Results

Creatinine levels in serum remained unchanged during the hospital stay in both groups without significant differences at any time point. Cystatin C levels in endovascular aneurysm repair patients significantly increased postoperatively and restored to values comparable to baseline at the discharge (0.865 ± 0.319 vs. *0.962 ± 0.353 vs. 0.921 ± 0.322, * p < 0.001). Cystatin C levels in patients treated with the open surgery was decreasing over time but not statistically significant comparing to Cystatin C values at the admission. However, decrease in Cystatin C serum levels in patients treated with conventional surgery resulted in statistically significant lower values compared to endovascular aneurysm repair patients both postoperatively and at the time of discharge (0.760 ± 0.225 vs. 0.962 ± 0.353, p < 0.05; 0.750 vs. 0.156, p < 0.05). Both multivariate linear regression models and propensity score adjustment confirm that, even after correction for previously observed intergroup differences, type of surgery, i.e. endovascular aneurysm repair is independently associated with the higher levels of Cystatin C both postoperatively and at the discharge.

Conclusions

Dynamics of Cystatin C levels have been proven as a more vulnerable marker of renal dysfunction. Endovascular aneurysm repair is associated with higher levels of kidney injury markers.

Progression to stage 3 and 4 chronic kidney disease and risk factor stratification following endovascular aortic aneurysm repair

Background

Risk of progression to various stages of chronic kidney disease (CKD) after endovascular aortic aneurysm repair (EVAR) is unknown. This study estimates progression rates to stage 3 and 4 CKD after EVAR and identifies potential predictors for progression.

Methods

EVAR cases (2006–2012) were retrospectively reviewed. Freedom of progression to CKD was estimated using Kaplan–Meier analysis, and predictors for progression were identified using Cox proportional hazards model.

Results

Two hundred and twelve consecutive patients at a single academic institution underwent EVAR for infrarenal aneurysms. Estimated freedom from progression to stage 3 CKD was 80%, 76%, and 63% at 6, 12, and 18 months, respectively, and for stage 4, 97%, 96%, and 93% at 6, 12, and 18 months, respectively. Stage 3 CKD predictors of progression included age (odds ratio (OR): 1.106, p = 0.001), diabetes (OR: 3.052, p = 0.04), perioperative use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers (OR: 3.249, p = 0.02), and operative blood loss (OR: 1.002, p < 0.01). Stage 4 predictors included preoperative hemoglobin (OR: 0.473, p = 0.04) and baseline renal function (OR: 0.928, p = 0.001). Intraoperative contrast administration did not impact CKD development.

Conclusions

Progression to stage 3 CKD after EVAR occurs more frequently and at a higher rate compared with progression to stage 4. Different risk factors are associated with progression to each of those stages of CKD.

Outcomes of Endovascular AAA Repair in Patients with Hostile Neck Anatomy Using Adjunctive Balloon-Expandable Stents

Hostile neck anatomy remains the predominant reason that patients are denied endovascular aneurysm repair (EVAR). We reviewed our experience of EVAR with use of prophylactic adjunctive proximal balloon-expandable stents in patients with hostile neck anatomy and adjunctive proximal balloon-expandable stents in patients with type I endoleaks. Of 140 patients who underwent EVAR between 2000 and 2004, we reviewed data for 19 patients in whom we used proximal balloon-expandable stents. By high-resolution computed tomography scan or angiography, hostile neck anatomy was classified as length <15 mm, neck diameters = 26 mm, circumferential thrombus at the proximal neck, angulated neck =60 degrees, and neck bulge or reverse taper necks. Patients were considered to have hostile anatomy if they met 1 or more of the above-cited criteria. All patients underwent AAA repair with commercially available endograft systems, Zenith (Cook, Bloomington, IN) and AneuRx (Medtronic/AVE, Minneapolis, MN). Balloon-expandable stents utilized included Cordis-Palmaz stents (17/19) and eV3 Max stents (2/19). Stents were deployed in the proximal graft with transrenal extension. AneuRx (18/19) and Zenith (1/19) endografts were used in all of the patients. Of the 19 patients, 15 had prophylactic stent placement for known hostile neck anatomy and 4 patients had stent placement for type I endoleak. Assisted primary technical success was achieved in all patients. Three patients had maldeployment of the endograft or proximal stent requiring additional endovascular interventions at the time of surgery. No endografts were deployed too low requiring stent placement. Procedure-related complications occurred in 2 of 19 patients. These included 1 operative death secondary to pneumonia and 1 patient who developed progressive renal failure. Short-term clinical success was achieved in 17 of 19 patients. Two patients required secondary interventions, 1 due to device migration with secondary conversion to open repair, and an endoleak, which, on angiogram, was a large type II endoleak successfully treated with coiling of the inferior mesenteric artery. One patient was observed to have a type II endoleak with no associated aneurysm enlargement. Short-term results suggest the use of prophylactic adjunctive balloon-expandable stents may decrease the incidence of secondary interventions related to hostile neck anatomy when used as an adjunctive measure with EVAR. Based on our experience, we feel EVAR may be offered to an expanded patient population with hostile neck anatomy with use of prophylactic balloon-expandable stents.

Renal Function after Endovascular Aortic Aneurysm Repair: A Single-Center Experience with Transrenal versus Infrarenal Fixation

Purpose:

To describe the short-term consequences of endovascular aortic aneurysm repair (EVAR) on renal function after infrarenal (IR) versus transrenal (TR) stent-graft fixation.

Methods:

Between December 1996 and January 2006, 369 consecutive patients were treated with EVAR. All patients had an AneuRx or a Talent stent-graft implanted using IR (AneuRx) or transrenal (Talent) fixation. Post-EVAR, a standardized follow-up scheme included computed tomography (CT) scanning and serum creatinine measurements at 2 days, 3 months, and 12 months. Postoperative renal dysfunction was defined as a >20% decrease in serum creatinine clearance compared to baseline, the presence of new-onset dialysis, or both. Of the 369 patients, 309 (291 men; mean age 71±7 years, range 63–82) had complete 1-year follow-up and were included in this study. An IR stent-graft was placed in 190 patients, and a TR stent-graft was placed in the remaining 119 patients.

Results:

At discharge, renal dysfunction occurred in 3.7% of the patients in the IR group versus 5.9% in the TR group (p=NS) and rose significantly to 13.7% in the IR group (p=0.001) and 15.1% in the TR group (p=0.02) at the 1-year follow-up. However, no significant difference was noted between the IR and TR groups at either time point. At the 1-year follow-up, at least 50% of renal dysfunction was caused by obstructions of (accessory) renal arteries and renal infarctions. During the follow-up interval, 3 (0.97%) of 309 patients underwent new-onset dialysis.

Conclusion:

Both infrarenal and transrenal fixation techniques in EVAR will lead to a significant rise in renal dysfunction during the first year. A few patients with dysfunction will require dialysis.

Risk factors for early renal dysfunction following endovascular aortic aneurysm repair and its effect on the postoperative outcome

PURPOSE

Renal insufficiency is associated with increased morbidity and death after endovascular aortic aneurysm repair (EVAR). However, the effect of postoperative acute kidney dysfunction on patient outcome has not been fully determined. This study aimed to determine the risk factors of early postoperative renal function decline using chronic kidney disease (CKD) staging and its effect on the clinical outcome.

METHODS

A retrospective analysis was performed on a prospectively maintained EVAR database. Pre- and postoperative CKD stages were determined for all patients according to the estimated glomerular filtration rate values.

RESULTS

We identified 135 patients who were treated with elective EVAR. CKD stage decline was observed in 25 (19 %) of the patients. Freedom from aneurysm-related death was significantly lower in patients with postoperative CKD progression compared with those with unchanged CKD stage. A shaggy aorta without oral beta-blocker administration and higher preoperative serum creatinine levels (>1.4 mg/dL) were found to be independent predictors of an early postoperative CKD stage decline.

CONCLUSIONS

Patients with postoperative CKD progression have an increased frequency of aneurysm-related death. The presence of a shaggy aorta, absence of oral beta-blocker administration and an increased preoperative creatinine level are independent predictors of early postoperative CKD progression.

A systematic review and meta-analysis indicates underreporting of renal dysfunction following endovascular aneurysm repair

Deterioration in renal function has been described after endovascular repair of abdominal aortic aneurysms (EVRs). The etiology is multifactorial and represents an important therapeutic target. A need exists to quantitatively summarize incidence and severity of renal dysfunction after EVR to allow better-informed attempts to preserve renal function and improve life expectancy. Here a systematic search was performed using Medline and Embase for renal function after EVR applying PRISMA statements. Univariate and multivariate random-effects meta-analyses were performed to estimate pooled postoperative changes in serum creatinine and creatinine clearance at four time points after EVR. Clinically relevant deterioration in renal function was also estimated at 1 year or more after EVR. Pooled probability of clinically relevant deterioration in renal function at 1 year or more was 18% (95% confidence interval of 14-23%, I2 of 82.5%). Serum creatinine increased after EVR by 0.05 mg/dl at 30 days/1 month, 0.09 mg/dl at 1 month to 1 year, and 0.11 mg/dl at 1 year or more (all significant). Creatinine clearance decreased after EVR by 5.65 ml/min at 1 month-1 year and by 6.58 ml/min at 1 year or more (both significant). Thus, renal dysfunction after EVR is common and merits attention.

Risk factors and impact of proximal fixation on acute and chronic renal dysfunction after endovascular aortic aneurysm repair using glomerular filtration rate criteria

BACKGROUND

The incidence of renal impairment relevant to proximal fixation of aortic endograft devices remains unclear.

METHODS

Retrospective cohort of 208 consecutive patients that underwent EVAR from 2006 to 2011. Estimated glomerular filtration rate (eGFR) was based on MDRD study equation. Acute kidney injury (AKI) and chronic kidney disease (CKD) were classified with ADIQ/RIFLE criteria and National Kidney Foundation criteria, respectively. Kaplan-Meier curve was applied to evaluate progression to CKD. Multivariate regression model was fit to identify predictors for developing AKI and CKD.

RESULTS

Suprarenal fixation group (SF) included 110 patients and infrarenal fixation group (IF) included 98 patients. Both groups had similar demographics, baseline eGFR, and renal-protection protocols. There was a trend for decreased use of contrast in IF group (median: 93.5 vs. 103 cc, P = 0.07). AKI occurred in 15% of patients in SF group and 19% of patients in IF group (RR: 1.24, P = 0.47). The freedom from progression to stage 3 or 4 CKD in the SF group was 0.76, 0.72, and 0.49 at 6, 12, and 18 months, respectively, while for IF group was 0.8, 0.73, and 0.68, respectively (P = 0.4). Increasing age (P = 0.07), lengthy procedures (P < 0.001), and baseline renal dysfunction (P < 0.001) were significant predictors for developing CKD. Contrast volume (P < 0.001) and ace-inhibitors (P = 0.07) were predictors for AKI.

CONCLUSION

Proximal fixation type has no significant effect on both acute and chronic renal function. Identification of modifiable perioperative risk factors may be used to improve renal function outcomes.

Suprarenal endograft fixation and medium-term renal function: systematic review and meta-analysis

BACKGROUND

Suprarenal fixation is widely used in endovascular aneurysm repair. Numerous small, underpowered studies have concluded that it does not increase the risk of renal impairment compared with infrarenal fixation. A recent meta-analysis demonstrated that renal infarction is more common with suprarenal fixation, but the effect on renal function remains unclear.

METHODS

Electronic abstract databases, article reference lists, and conference proceedings were searched for series reporting renal function data after suprarenal fixation. There was considerable study heterogeneity with respect to key factors such as pre-existing renal dysfunction and length of follow-up. Authors were contacted to obtain individual patient data for a pooled reanalysis using standardized criteria.

RESULTS

Of 46 potentially relevant citations, only 11 were eligible for inclusion in the meta-analysis. Complete data sets were available for four studies (1065 patients), with a median follow-up of 33 months. Kaplan-Meier curves were constructed for postoperative renal impairment in the suprarenal fixation and infrarenal fixation groups and compared by the log-rank test. Median time free of renal impairment was 38.5 months in the infrarenal fixation group compared with 32.4 months in the suprarenal fixation group (P = .0038). However, to account for significant methodologic differences, further analysis was required using a Weibull regression model fitted in open Bayesian inference using Gibbs sampling (BUGS). The pooled hazard ratio for deterioration of renal function after suprarenal fixation was 0.6 (95% confidence interval, 0.3-10).

CONCLUSION

Currently available data are insufficient to determine the precise effect of suprarenal fixation on medium-term renal function. Conventional Kaplan-Meier analysis of the pooled data set suggested that suprarenal fixation increased the risk of renal dysfunction; however, the effect disappeared when sophisticated statistical modelling was performed to account for study heterogeneity. A randomised controlled trial of suprarenal fixation may resolve this issue.

Effect of suprarenal fixation of aortic stent-grafts on the renal artery ostia: assessment of morphological changes by virtual intravascular endoscopy

PURPOSE

To investigate the morphological effects of suprarenal fixation of aortic stent-grafts on the renal artery ostia (RaO) by analysis of suprarenal stent wire distribution and vascular calcification across the RaO using virtual intravascular endoscopy (VIE).

METHODS

Fourteen consecutive patients (11 men; mean age 75 years) from a single institution were studied following endovascular aortic aneurysm repair (EVAR) using the Zenith endograft system from September 1999 to March 2002. Imaging assessment included computed tomographic (CT) measurement of renal artery intraluminal ostial diameter and quantification and analysis of uncovered stent struts across the RaO and radiological determination of RaO calcification. Morphological changes following EVAR at 3 time points (before and within 1 week after stent-grafting, and at the most recent follow-up) were compared for each patient to determine whether suprarenal stent struts or RaO calcification affected intraluminal ostial diameter. Renal function was assessed by temporal measurements of serum creatinine concentration and creatinine clearance.

RESULTS

The renal ostium was distorted to variable degrees in all cases at a mean follow-up of 41+/-6.6 months. An increase in ostial diameter was identified in most patients if the right RaO was calcified when comparing the 1-week postoperative and most recent follow-up CT images (p<0.05). There was no direct relationship between the number of stent struts crossing the RaO and the morphological/dimensional changes (p>0.05). Renal function was not significantly affected.

CONCLUSION

Patients undergoing suprarenal fixation of aortic stent-grafts experienced morphological changes of the RaO to a variable extent at midterm follow-up. Although the presence of stent struts did not significantly affect dimensional changes, we observed that calcification at the renal artery ostium may influence the development of atherosclerotic effects as a direct relationship between the calcification and ostial diameter. Future studies utilizing VIE to determine the long-term safety of this technique in these particular patients requires investigation.

Feasibility of renal artery stenting before, during, and after endovascular aneurysm repair with suprarenal fixation endograft

Suprarenal fixation by means of proximal bare stent may help prevent endograft migration and proximal endoleak. It seems not to compromise renal perfusion and function; however, it is still unclear whether its presence is in conflict with stenting of the renal arteries to treat associated renal stenosis. We report five cases of renal artery stenting performed before, at the same time, or after endovascular treatment of abdominal aortic aneurysm with a suprarenal fixation endograft (Zenith; Cook, Biaverskov, Denmark). Suprarenal fixation endograft seems not to affect renal artery stenting regardless the timing of the procedure.

Surgery Insight: advances in endovascular repair of abdominal aortic aneurysms

Despite improvements in diagnostic and therapeutic methods and an increased awareness of their clinical significance, abdominal aortic aneurysms (AAAs) continue to be a major source of morbidity and mortality. Endovascular repair of AAAs, initially described in 1990, offers a less-invasive alternative to conventional open repair. The technology and devices used for endovascular repair of AAAs have progressed rapidly and the approach has proven to be safe and effective in short to midterm investigations. Furthermore, several large trials have demonstrated that elective endovascular repair is associated with lower perioperative morbidity and mortality than open repair. The long-term benefits of endovascular repair relative to open repair, however, continue to be studied. In addition to elective repair, the use of endovascular repair for ruptured AAAs has been increasing, and has been shown to be associated with reduced perioperative morbidity and mortality. Advances in endovascular repair of AAAs, including the development of branched and fenestrated grafts and the use of implantable devices to measure aneurysm-sac pressures following stent-graft deployment, have further broadened the application of the technique and have enhanced postoperative monitoring. Despite these advances, endovascular repair of AAAs remains a relatively novel technique, and further long-term data need to be collected.

Durability of renal artery stents in patients with transrenal abdominal aortic endografts

OBJECTIVE

The management of renal artery stenosis in patients with abdominal aortic aneurysms continues to be complex and technically challenging despite advances in endovascular therapy. There is growing concern about the durability of renal artery stents in the setting of transrenal abdominal aortic endografts. This study reports a single-center experience of renal artery stenting with transrenal abdominal aortic endografts for patients with renal artery stenosis.

METHODS

All patients undergoing endovascular abdominal aortic aneurysm repair preceded or followed by renal artery stent placement between January 1999 and December 2005 were retrospectively reviewed from a prospectively gathered endovascular database. Patients were surveyed after renal stent procedures with multidetector computed tomography angiography or duplex sonography. The surveillance data were analyzed for primary patency of the renal artery stent at 6 months, incidence of complications, need for secondary interventions, and changes in creatinine clearance (CrCl).

RESULTS

Sixty-two renal artery stents were placed in 56 patients (44 men, 12 women) with a mean age of 77.3 years (range, 61 to 94 years). Forty-one were placed before the endograft procedure, eight were placed during the endograft procedure, and 13 were placed postoperatively. There were no major or minor complications related to the renal artery stent procedures. Transrenal aortic endografts were used in 44 of the 56 patients, and 12 had devices with infrarenal fixation. The mean follow-up was 18.5 months (range, 1 to 73 months). The 6-month primary patency, which could be evaluated for 51 renal artery stents, was 97.4% (37/38) in patients with transrenal fixation and 84.6% (11/13) in patients with infrarenal fixation. The overall rate of in-stent restenosis was 8.5% (4/47) in the transrenal fixation group and 20.0% (3/15) in the infrarenal fixation group. The overall occlusion rate was 2.1% (1/47) in the transrenal fixation group and 0% (0/15) in infrarenal fixation group. Five (83.3%) of six patients underwent successful treatment of in-stent restenosis with placement of a new stent in all five cases. CrCl decreased in the total group by 4.2 +/- 11.8 mL/min, by 4.7 +/- 12.0 mL/min in patients with transrenal fixation, and by 2.2 +/- 11.0 mL/min in patients with infrarenal fixation.

CONCLUSION

The presence of a transrenal aortic endograft did not affect the outcome of the renal artery revascularization procedure in this cohort. Renal artery stenting in the presence of transrenal abdominal aortic endografts appears to be a safe procedure without adverse effect on renal artery stent patency or renal function.

Short to Midterm Outcomes of Fenestrated Endovascular Grafts in the Treatment of Abdominal Aortic Aneurysms:A Systematic Review

PURPOSE

To perform a systematic review of the short to midterm outcomes of fenestrated endovascular grafts in patients with abdominal aortic aneurysms (AAA).

METHODS

A search of PubMed and Medline databases for English-language literature was performed to find studies published between 1999 and 2006. Studies investigating the short to midterm results of fenestrated endovascular grafts for AAA were analyzed for clinical outcomes and postprocedural complications.

RESULTS

Nineteen studies involving fenestrated endovascular grafting were retrieved, and 6 of them met criteria for inclusion in the analysis. The remaining studies were excluded because they dealt with technical or case reports or cumulative addition of previous cases. Pooled estimates (95% confidence interval) of postprocedural complications were 1.1% (0.4%-2.7%) for 30-day mortality; 8.3% (2.9%-13.6%) for late mortality; 97% (92%-100%) and 90% (85%-95%) for perfusion of fenestrated vessels at perioperative and late follow-up, respectively; 13.3% (4.1%-22.5%) for postprocedural renal dysfunction; and 11.2% (3.2%-22.5%) and 9.4% (2.6%-16.3%) for early and late endoleak, respectively. There was correlation between preoperative renal insufficiency and postprocedural renal dysfunction, although this was not a statistically significant difference (p=0.2).

CONCLUSION

Our systematic review showed that fenestrated endovascular grafting provides an alternative technique to treat patients with complex aneurysm necks, achieving lower mortality than open repair under comparable conditions. Preoperative renal impairment is a strong indicator of postoperative renal dysfunction. Long-term stability and patency of the fenestrated vessels deserves to be validated.

The Mid-term Effect of Bare Metal Suprarenal Fixation on Renal Function Following Endovascular Abdominal Aortic Aneurysm Repair

OBJECTIVE

The aim of this study was to assess the mid term effect of proximal bare metal fixation design on renal function in patients undergoing endovascular repair (EVR) of abdominal aortic aneurysm (AAA).

METHODS

Consecutive EVR patients for AAA from December 1995-2001 were included and grouped to either infrarenal (Group 1) or uncovered suprarenal (Group 2) fixation. Peri-operative renal function and at 6, 12 and 24 months was determined by serum creatinine (sCr mmol l(-1)) and Cockroft-Gault creatinine clearance (CrC ml min(-1)). Changes in renal function were compared using non-parametric analysis.

RESULTS

Of the 179 EVR procedures during this six-year period, paired renal data was available for 135 patients at a minimal follow-up of 6 months (Gp1, n = 63; Gp2, n = 72). Median pre-EVR sCr and CrC were 113, 57 in Group 1 and 108, 58 in Group 2, p = NS. There was no significant deterioration in renal function within or between either group at 2 years post-EVR: median sCr, CrC values were 118, 56 (Group 1) and 111, 56 (Group 2), all p = NS.

CONCLUSION

This study suggests mid-term renal function remains unaffected following EVR of AAA, irrespective of proximal fixation type. Designs to improve stent durability and EVR applicability do not appear to compromise renal function.

Comparison of renal function after endovascular aneurysm repair with different transrenally fixated endografts

OBJECTIVE

Transrenal fixation of abdominal aortic endografts may provide a more secure proximal attachment with few deleterious effects with respect to renal function. This study's purpose was to determine whether different metals used in two commercially available endografts (Cook Zenith and Medtronic Talent) result in different effects on renal function when placed across renal ostia.

METHODS

A total of 140 consecutive patients, between August 2003 and April 2005, who underwent elective endovascular repair of an aortic aneurysm with a nitinol or stainless steel-based endograft with transrenal fixation were reviewed with a mean follow-up period of 5.5 months (range, 1-22 months). The main outcome variable was the percentage change in creatinine clearance (CrCl), which was determined before surgery and at the most recent follow-up. Multiple regression analysis was performed to analyze the contribution of various factors to any deterioration in renal function.

RESULTS

The 140 patients were predominantly male (86%), with a mean age of 75 years (range, 56-92) and a mean aneurysm diameter of 62 mm (range, 42-110 mm). The mean intraoperative contrast use was 67 mL (range, 45-160 mL), and after surgery these patients received a mean of 3 surveillance computed tomographic scans (range, 1-7). Nineteen cases (13.6%) required deliberate accessory renal artery coverage. CrCl did not change significantly after surgery; the mean change in CrCl at the end of follow-up was a 2.5% decrease. There was no difference in the reduction in CrCl between endograft types. Only 14.3% of patients experienced a greater than 20% decrease in CrCl. Multiple regression analysis failed to show a relationship between change in renal function and age, sex, aneurysm diameter, infrarenal neck dimensions, endograft type, coverage of accessory renal arteries, intraoperative contrast volume, preoperative CrCl, and postoperative computed tomographic scans. Length of follow-up was an independent predictor (P = .04).

CONCLUSIONS

Transrenal endograft fixation results in little deterioration in renal function during intermediate follow-up. The few patients who do experience a decline in renal function do so independently of any features related to the initial endovascular repair, and there is no difference in renal deterioration between endografts with nitinol and stainless steel transrenal bare metal stents.

Renal interventions after abdominal aortic aneurysm repair using an aortic endograft with suprarenal fixation

BACKGROUND

Our aim was to determine whether suprarenal fixation in endografts compromises renal artery (RA) flow and whether subsequent RA intervention is precluded by the stent struts.

METHODS

Prospectively acquired data from 104 patients with endovascular aneurysm repair (EVAR) of an abdominal aortic aneurysm using the Zenith endograft (Cook, Inc., Bloomington, IN) were analyzed. The Zenith device uses a 26-mm, uncovered, barbed Z stent for suprarenal function.

RESULTS

No RA stenosis, occlusion, or infarction resulted from the suprarenal stent. In 3 of 104 (2.9%) patients, RA compromise (2 stenoses, 1 occlusion) was caused by impingement of graft material on the lowermost RA. The 2 RA stenoses were stented successfully at 1 and 7 months post-EVAR. Six of 104 (5.8%) patients developed late stenoses unrelated to the endograft: all were stented successfully from 19 to 36 months after EVAR. One patient with severe RA stenosis had balloon angioplasty pre-EVAR and then was stented electively 6 weeks post-EVAR.

CONCLUSIONS

Our data show that the suprarenal fixation of the Zenith aortic endograft does not cause RA stenosis, occlusion, or infarction, nor does it preclude post-EVAR renal artery intervention.

Transrenal Fixation of Aortic Stent-Grafts: Short- to Midterm Effects on Renal Function—A Systematic Review

PURPOSE

To perform a systematic review of the short- to midterm effects of transrenal fixation of aortic stent-grafts on renal function in patients with abdominal aortic aneurysms.

MATERIALS AND METHODS

A search of the PubMed, MEDLINE, and EMBASE databases for English-language literature was performed. Studies with at least 10 patients were included for data analysis. Only studies on transrenal fixation of aortic stent-grafts that included follow-up results for renal function were included. A log-linear model was used for meta-analysis to compare transrenal fixation with infrarenal fixation.

RESULTS

Twenty-two studies met the inclusion criteria. Because two studies analyzed the same group of patients, one was excluded, for a total of 21 studies. Comparisons between transrenal fixation and infrarenal fixation were found in seven studies. For transrenal versus infrarenal fixation, the combined odds ratio, 95% confidence interval, and P value were found to be statistically significant with respect to postprocedural renal infarction only (combined odds ratio, 5.189; 95% confidence interval: 3.198, 8.420; P < .001). No significant difference was found between transrenal and infrarenal fixation with respect to renal dysfunction, renal artery occlusion, or endoleaks (P > .05).

CONCLUSION

Transrenal fixation of aortic stent-grafts seems to be a relatively safe alternative compared with infrarenal fixation in terms of short- to midterm follow-up. Postprocedural renal infarction, however, was significantly higher for transrenal fixation.

Endovascular aneurysm repair with suprarenal vs infrarenal fixation: A study of renal effects

OBJECTIVES

Although suprarenal fixation may be of benefit during endovascular aneurysm repair (EVAR), its safety with regards to renal effects remains uncertain. To date, there has been no controlled study of the topic, with most reports relying upon single-center experiences that use heterogeneous patient populations and devices from different manufacturers. The purpose of this analysis was to evaluate the effect of suprarenal fixation on renal function by comparing homogeneous patient populations receiving EVAR grafts from a single manufacturer that are identical in design and delivery method, except for utilizing either suprarenal (SR) or infrarenal (IR) fixation.

METHODS

During two pivotal US Food and Drug Administration trials, 283 patients underwent EVAR with the Powerlink bifurcated graft. The trials' inclusion and exclusion criteria and grafts were identical except for fixation scheme. Clinical, laboratory, and computed tomographic (CT) data were retrospectively reviewed. A comparison of preoperative, perioperative (1 to 7 days), and postoperative (>7 days) alterations in serum creatinine (SCr), creatinine clearance (CrCl), and blood pressure was performed. Renal adverse events were determined by CT scan and clinical chart review and included renal infarction, renal artery stenosis (either progressive or requiring renal stent placement), and renal artery occlusion.

RESULTS

Both SR and IR groups demonstrated a significant increase in SCr and a decrease in CrCl over time. No significant difference in SCr or CrCl existed between groups during any time period. There were no differences in postoperative renal impairment (IR, 10.2%; SR, 7.6%, P = .634), the need for hemodialysis (IR, 0.7%; SR, 0%, P = 1.00), or systolic and diastolic blood pressure during subsequent follow-up between treatment groups. There was no significant difference in the number of renal adverse events detected by CT between the IR (10, 6.8%) and SR (3, 3.8%) groups (P = .550).

CONCLUSION

Suprarenal fixation does not lead to a significant increase in acute renal events, renal impairment, or alteration in blood pressure compared with infrarenal fixation. Patients undergoing aneurysm repair with devices that use either suprarenal or infrarenal fixation develop progressive renal dysfunction over time. Further studies are needed to determine the long-term effects of suprarenal fixation on renal function and progression of renal artery stenosis.

The impact of aortic endografts on renal function

OBJECTIVE

To determine the impact on late postoperative renal function of suprarenal and infrarenal fixation of endografts used to treat infrarenal abdominal aortic aneurysm (AAA).

METHODS

Retrospective analysis of 277 patients treated from 2000 to 2003 with three different endografts at two clinical centers. Five patients on dialysis for preoperative chronic renal failure were excluded. Group IF of 135 patients treated with an infrarenal device (Medtronic AneuRx) was compared with group SF of 137 patients treated with a suprarenal device (106 Cook Zenith and 31 Medtronic Talent). Renal function was evaluated by calculating preoperative and latest postoperative creatinine clearance (CrCl) using the Cockcroft formula. Patients who developed a >20% decrease in CrCl were considered to have significantly impaired renal function.

RESULTS

There were no significant differences in patient age, sex, aneurysm size, preoperative risk factors, dose of intra- and postoperative contrast, or baseline CrCl (IF: 69.3 mL/min, SF: 71.7 mL/min, P = .4). Follow-up time of 12.2 months was the same in both groups. CrCl decreased significantly during the follow-up period in both groups (IF: 69.3 mL/min to 61.7 mL/min, P < .01; SF: 71.7 mL/min to 64.9 mL/min, P < .03). Postoperative CrCl (IF: 61.7 mL/min, SF: 64.9 mL/min, P = .3), and the rate of CrCl decrease during the follow-up period (IF: -10.9%, SF: -9.5%, P = .2) was not different between the two groups. The number of patients with a >20% decrease in CrCl was not different between the two groups (IF: n = 35 [25.9%], SF: n = 41 [29.9%], P = .46). However, the magnitude of decrease in CrCl in patients with renal impairment was greater in patients treated with suprarenal fixation endografts (SF: -39%) compared with those treated with infrarenal endografts (IF: -31%, P = .005). This greater degree of renal impairment was not due to identifiable differences in preoperative risk factors, age, or baseline CrCl. No patients in these series required dialysis.

CONCLUSIONS

Regardless the type of endograft used, there is a 10% decrease in CrCl in the first year after endovascular aneurysm repair. Suprarenal fixation does not seem to increase the likelihood of postoperative renal impairment. Decline in renal function over time after endovascular aortic repair is probably due to multiple factors, and measures known to be effective in protecting kidneys should be considered for these patients. Long-term follow-up with measurement of CrCl, along with renal imaging and regular blood pressure measurements, should be performed to detect possible late renal dysfunction. Prospective studies comparing suprarenal versus infrarenal fixation are needed to confirm those results.

Incidence of Renal Infarctions After Transrenal Stent Placement in an Animal Model

PURPOSE

To evaluate the incidence and appearance of renal infarctions after transrenal stent placement in an animal model.

METHODS

An aortic stent was placed via a femoral approach in 20 female Merino sheep. Ten animals had intentional coverage of one renal ostium with the bare struts, 1 sheep had both renal artery ostia covered, and the other 9 sheep had no stent impingement on the renal orifices. Animals were sacrificed after 3 to 12 months (mean 6) for gross pathological and histological evaluation. Infarction locations and patterns were evaluated and correlated to stent placement.

RESULTS

Of the 40 renal arteries, coverage was proven at autopsy in 12 cases; the remaining 28 arteries were free of any stent overlay. Overall, 14 (35%) renal infarctions were detected; 7 were found in the 12 arteries with a transrenal stent (58.3% incidence in covered renal arteries). By comparison, the other 7 infarctions were found in the 28 unaffected arteries (25% incidence in noncovered renal arteries; p = 0.04). All infarctions appeared to be well-defined punctate lesions.

CONCLUSIONS

A transrenal stent position in the abdominal aorta is related to increased renal infarctions in an animal model.

Transrenal fixation of aortic stent-grafts: current status and future directions

Aortic stent-graft repair has been widely used in clinical practice for more than a decade, achieving satisfactory results compared to open surgical techniques. Transrenal fixation of stent-grafts is designed to obtain secure fixation of the proximal end of the stent-graft to avoid graft migration and to prevent type I endoleak. Unlike infrarenal deployment of stent-grafts, transrenal fixation takes advantage of the relative stability of the suprarenal aorta as a landing zone for the uncovered struts of the proximal stent. These transostial wires have sparked concern about the patency of the renal arteries, interference with renal blood flow, and effects on renal function. Although short to midterm results with suprarenal stent-grafts have not shown significant changes in renal function, long-term effects of this technique are still not fully understood. This review will explore the current status of transrenal fixation of aortic stent-grafts, potential risks of stent struts relative to the renal ostium, alternative methods to preserve blood flow to the renal arteries, and future directions or developments in stent-graft design to prevent myointimal proliferation around the stent struts.

Effect of Suprarenal Stent Struts on the Renal Artery with Ostial Calcification Observed on CT Virtual Intravascular Endoscopy

OBJECTIVES

The behaviour of stent struts crossing the renal ostia and their effect on renal ostia configuration is not well understood. The study aims to investigate whether suprarenal stent struts affect the morphological change of the renal artery with ostial calcification observed on CT virtual intravascular endoscopy.

METHODS

Nine patients with abdominal aortic aneurysms undergoing suprarenal fixation of stent grafts were included in the study. All patients received a Zenith endovascular graft with uncovered suprarenal components placed above the renal arteries. Renal ostial calcification and configuration of stent wires crossing the renal ostium were characterized in each patient and maximal transverse and longitudinal diameters of the renal ostia were measured on virtual endoscopy pre- and post-stent grafting.

RESULTS

There were altogether 17 renal ostia assessed with one patient having atrophic left kidney and no renal ostium being observed. Ostial calcification was found in five of the left renal ostia and five of the right renal ostia with one patient having bilateral ostial calcification. There was no significant difference between the renal ostial diameters measured pre- and post-stent grafting (p>0.05). Suprarenal stent struts were found to cross the renal ostia in various configurations observed on virtual endoscopy. All of the renal arteries were patent on follow-up CT scans after suprarenal fixation without stenosis or occlusion being observed. One patient with atrophic left renal artery developed renal failure following suprarenal stent grafting and received renal dialysis, while in the remaining cases median serum creatinine level did not change significantly.

CONCLUSIONS

Suprarenal stent struts did not significantly affect the renal ostia with ostial calcification in terms of the diameter measurements and renal function. Further studies deserve to investigate the long-term effect of stent struts on the renal artery in terms of cross-sectional area reduction caused by stent wires and ostial calcification.

Analysis of renal function after aneurysm repair with a device using suprarenal fixation (zenith AAA endovascular graft) in contrast to open surgical repair

PURPOSE

This study was undertaken to assess the effect on renal function of open surgery and endovascular abdominal aortic aneurysm (AAA) repair with suprarenal fixation with the Zenith device.

METHODS

Data for 279 patients with similar preoperative comorbid conditions were prospectively analyzed after AAA repair. One hundred ninety-nine patients underwent endografting with the Zenith AAA Endovascular Graft, which incorporates suprarenal fixation (Zenith standard risk group, ZSR), and 80 patients underwent open surgery (standard surgical risk group, SSR). Endovascular repair was also performed in 100 patients considered poor candidates for open repair (Zenith high risk group, ZHR). Serum creatinine concentration (SCr) and anatomic defects were assessed before the procedure, before discharge, and at 1, 6, 12, and 24 months in all patients who underwent endovascular repair, and before the procedure and at 1 and 12 months in patients who underwent open surgical repair (only SCr was measured before discharge). Renal function was also analyzed, with a creatinine clearance calculation (Cockcraft-Gault). Renal insufficiency was defined as an increase in SCr greater than 30% from a preoperative baseline value, any SCr concentration in excess of 2.0 mg/dL, or any need for dialysis. Cumulative renal infarction and arterial occlusion rates were calculated with computed tomographic, ultrasonographic, and angiographic data, and reported as cumulative values.

RESULTS

Despite the initially superior renal function in the ZSR group at the pre-discharge evaluation (P =.01), there were no differences at 12 months with respect to rise in SCr greater than 30% (ZSR, 16%, vs SSR, 12%; P =.67), SCr rise greater than 2.0 mg/dL (ZSR, 2.5%, vs SSR, 3.4%; P =.66), incidence of renal artery occlusion (ZSR, 1%, vs SSR, 1.4%; P >.99), or infarction (ZSR, 1.5%, vs SSR, 1.4%; P >.99). Only one patient in each group required hemodialysis. Of note, both groups of patients demonstrated a reduction in creatinine clearance over 12 months, which then stabilized or improved by 24 months for ZSR patients.

CONCLUSIONS

Renal dysfunction occurs in a subset of patients regardless of type of repair (open or endovascular with suprarenal fixation). The cause of renal dysfunction after open or endovascular repair with a suprarenal stent is probably multifactorial. The observed dysfunction occurs in a small number of patients, and the effect in the endovascular group (no data for the surgical group at 24 months) appears to be transient. The initial dysfunction, apparent in both groups over 12 months of follow-up, stabilizes or improves at 12 to 24 months.