Renal infarction following endovascular aortic aneurysm repair: incidence and clinical consequences

Endovascular repair of abdominal aortic aneurysm in octogenarians: clinical outcomes and complications

Background

Endovascular aneurysm repair (EVAR) is associated with decreased perioperative morbidity and mortaliy in comparison with open repair, and thus octagenarians are traditionally offered EVAR given their age and medical comorbidities. The aim of this study was to investigate outcomes and predictors of complications associated with EVAR in octogenarians.

Methods

We conducted a retrospective chart review of consecutive patients aged 80 years and older who received an EVAR between August 2010 and January 2017 at a single centre in Toronto, Ontario. We conducted univariate comparisons and then completed logistic regression to determine predictors of complications. We used Kaplan-Meier analysis to explore survival times.

Results

A total of 154 octogenarians underwent an EVAR during the study period for an infrarenal aneurysm with a mean size of 64.8 (standard deviation [SD] 12.7) mm. The mean age of the patients was 84.1 (SD 3.7) years, and most patients (81%) were men. Eighteen patients presented with a ruptured abdominal aortic aneurysm (AAA). Ninety-five (62%) patients sustained a complication. Fifty percent of patients experienced an intraoperative complication. A majority of these (77%) resulted in an endoleak, with type II endoleaks requiring no further intervenion being the most common (58%, n = 45). The remaining complications (n = 70) occurred postoperatively, with myocardial ischemia (n = 24) and dysrhythmias (n = 10) being the most common. Past aortic surgery (χ2 = 8.62, p = 0.014, Cramer V = 0.27) was found to be a multivariate predictor of complications. Most patients (88%) continued follow-up to an average of 20.9 months. Twenty-one patients (13%) died. Nine of these deaths (43%) occurred during the index admission and involved a ruptured AAA. Past aortic surgery was the only predictor of vascular complications. The mean survival time after EVAR was 57.63 months for patients without events.

Conclusion

Endovascular aneurysm repair in octogenarians is a suitable form of therapy with acceptable short- and long-term results in the elective setting. Past aortic surgery was a predictor of complications in this population.

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.

Monocentric Evaluation of Chimney Versus Fenestrated Endovascular Aortic Repair for Juxtarenal Abdominal Aortic Aneurysm

BACKGROUND

With approval of on-label fenestrated (F-) endovascular aortic repair (EVAR), concerns regarding long-term patency and endoleaks (ELs) after chimney graft (CG)-EVAR were raised. To add supportive data on the value of this technique, we chose to report the midterm results of CG-EVAR in a single center with standardized methods and to compare them to F-EVAR.

METHODS

A retrospective analysis of prospectively gathered data from January 2010 to January 2015 was conducted, and patients with excessive comorbidities for open repair treated by CG-EVAR or F-EVAR were included.

RESULTS

Ninety patients were treated by F-EVAR (88 men, 198 targets vessels) and 31 by CG-EVAR (26 men, 39 targets vessels, 12.9% treated in emergency; P = 0.001). Mean age was significantly higher in the CG group (71.3 ± 8.2 years in the FG group vs. 75.3 ± 6.6; P = 0.02), and there were significantly more patients suffering from preoperative chronic kidney disease (CKD) (13 [14.4%] treated by F-EVAR vs. 12 [38.7%]; P = 0.009). Target vessels were successfully reconstructed in 99.0% (196/198 target vessels) vs. 97.4% (38/39 target vessels) of cases (P = 0.3). In-hospital mortality was significantly higher after CG-EVAR (3.3% vs. 16.1%; P = 0.03). Incidence of acute kidney injury and CKD did not differ significantly between both groups. At 12 and 24 months, overall survival was 91.4% after F-EVAR vs. 82.1% and 81.8% vs. 69.0% (P = 0.4), estimated freedom from aneurysm related reintervention was 93.3% vs. 82.1% and 84.9% vs. 82.1% (P = 0.6), and target vessel's primary patency rate was 97.5% vs. 89.9% (P = 0.06), respectively. Freedom from type I EL's survival was significantly higher after F-EVAR at 12 and 24 months (100% vs. 89.0% and 97.7% vs. 89.0%; P = 0.01), but aneurysm maximum transverse diameter decrease did not differ significantly.

CONCLUSIONS

There are potential advantages to CG-EVAR with off-the-shelf availability, versatility, and low-profile devices. In this series, patients treated by CG-EVAR showed promising and durable midterm results compared with F-EVAR. CG-EVAR and F-EVAR should not be apprehended as opposed strategies but more as complementary ones, while the best indications for CG-EVAR are clarified.

Incidence of Renal Infarctions after Endovascular AAA Repair: Relationship to Infrarenal versus Suprarenal Fixation

Purpose:

To analyze the incidence and etiology of renal infarctions following endovascular abdominal aortic aneurysm (AAA) repair detected on computed tomography (CT) and determine any association with infrarenal versus suprarenal fixation.

Methods:

Between August 1994 and October 2001, 663 patients (604 men; mean age 68.5 years, range 40–98) underwent endovascular AAA repair with predominately bifurcated (505, 77%) stent-grafts. About a third (202, 30%) of the devices were deployed in a suprarenal position. Contrast-enhanced CT scans were performed on days 10, 90, and 365 after operation and then annually. Two radiologists blinded to procedural details compared the preoperative and postoperative scans to identify renal infarctions from inadvertent renal artery occlusion by the endograft. Only patients with inadvertent infarctions were analyzed relative to endograft fixation position and stent-graft type.

Results:

Mean follow-up was 37 months (range 0.1–75). Overall renal infarction rate was 11.9% (n=79); 23 (3.4%) patients suffered from limited, segmental infarction due to intentional covering of preoperatively diagnosed accessory renal arteries. Unintentional renal ischemia was identified in 56 (8.5%) patients. In this subgroup, 39 (19%) were observed in the 202 patients with suprarenal fixation versus 17 (3.7%) in the 461 stent-grafts positioned infrarenally (RR 3.35, 95% CI 2.20 to 5.04, p < 0.00001). There was a significant correlation between the incidence of infarction and the device type (14.3% for modular grafts versus 5.6% for unibody designs, p = 0.0002). Seventeen (2.6%) patients suffered from unilateral kidney loss, with dialysis required in 2 cases. Creatinine and urea showed no significant postoperative elevation in the overall patient population, but both levels were significantly (p < 0.02) elevated in patients with complete unilateral renal infarcts.

Conclusions:

Transrenal fixation of aortic endografts had a 3-fold higher risk for renal infarction in this large patient population. There is no significant difference for specific endografts, but modular designs were associated with a higher rate of renal infarction. The need to occlude preoperatively diagnosed accessory renal arteries with an endograft should be considered a contraindication for current available devices.

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.

Predictors of Diffuse Renal Microembolization Following Endovascular Repair of Abdominal Aortic Aneurysms

We evaluated the incidence, risk factors, and clinical consequences of renal microembolic events following endovascular aneurysm repair using suprarenal or infrarenal fixation. Pre- and postoperative (1 month) computed tomographic angiograms were reviewed for new renal perfusion defects. Suprarenal aortic and infrarenal neck thrombus load was classified by circumference involved and thrombus thickness. Serum creatinine was measured preoperatively, on the first postoperative day, and 1 month postoperatively. Among 136 patients, 8 (5.9%) had bilateral microembolic cortical defects. Patients with moderate or severe suprarenal thrombus were more likely to have renal microemboli than those with no or mild suprarenal thrombus (17% vs 0%; p < .001). Similarly, patients with moderate or severe infrarenal neck thrombus were more likely to have renal microemboli than those with no or mild infrarenal thrombus (9.6% vs 1.5%; p = .08). Severe infrarenal thrombus was independently predictive of microembolization (odds ratio 15.0; 95% confidence interval 1.6–142; p = .018). There was no statistically significant difference in the incidence of renal microembolization when comparing suprarenal and infrarenal fixation (8.2% vs 4.0%; p = .47). Changes in creatinine from baseline were not different in those with or without renal microemboli. Renal microembolization is an uncommon but distinct radiographic finding that is more associated with significant neck thrombus than fixation level.

Quantified Aortic Luminal Irregularity as a Predictor of Complications and Prognosis After Endovascular Aneurysm Repair

Atheromatous degeneration of the aorta is considered to be a risk factor for postoperative embolic complications after endovascular treatment, and is associated with a high incidence of vascular events in the long term. We devised a method to quantify the shagginess of the aorta using contrast-enhanced computed tomography (CT) images. This study examined the method's validity and prognostic usefulness in patients undergoing elective endovascular abdominal aortic aneurysm repair (EVAR). We retrospectively investigated 427 patients who underwent elective EVAR between 2007 and 2013. Preoperative contrast-enhanced CT images with a slice thickness of 1 mm were analyzed using a workstation, and the degree of aortic luminal irregularity from the level of the left subclavian artery ostium to that of the celiac artery ostium was quantified by computing a shagginess score. We compared the computed scores with subjective visual assessments of aortic shagginess. Subsequently, we evaluated the relationship between the computed scores and postoperative prognosis. The shagginess scores were significantly correlated with the visual assessments of the aortic lumen, which were performed by 5 experienced vascular surgeons (rho ranged from 0.564-0.654, all P < 0.001). Multiple logistic regression analysis demonstrated that the shagginess score was independently associated with the development of renal impairment within a month after EVAR (odds ratio, 2.78; 95% confidence interval [CI], 1.83-4.22, P < 0.001). The shagginess score was significantly higher in patients who suffered postoperative intestinal and peripheral ischemic complications, as compared with those who did not (P < 0.001). The mean postoperative follow-up period was 1207 ± 641 days. Cox proportional hazards regression showed that the shagginess score was a significant independent predictor of all-cause and cardiovascular mortality (hazard ratio [HR], 1.37; 95% CI, 1.09-1.72, P = 0.007, and HR, 1.51; 95% CI, 1.04-2.18, P = 0.030, respectively). The results suggest that the shagginess score provides a quantitative reflection of aortic luminal irregularity. It may serve as a useful predictive factor for postoperative renal function deterioration, embolic complications, and long-term mortality after elective EVAR.

Acute renal infarction presenting with acute abdominal pain secondary to newly discovered atrial fibrillation: a case report and literature review

We report an 85-year-old female with known history of recurrent diverticulitis presented with abdominal pain. It was believed that the patient again needed to be treated for another diverticulitis and was started on the routine treatment. The initial CT scan of abdomen showed renal infarcts bilaterally that were confirmed by a CT with and without intravenous contrast secondary to unknown cause. An ECG found accidentally that the patient was in atrial fibrillation, which was the attributed factor to the renal infarctions. Subsequently, the patient was started on the appropriate anticoagulation and discharged.

Renovascular hypertension and ischemic nephropathy

Renovascular disease remains among the most prevalent and important causes of secondary hypertension and renal dysfunction. Many lesions reduce perfusion pressure including fibromuscular diseases and renal infarction, but most are caused by atherosclerotic disease. Epidemiologic studies establish a strong association between atherosclerotic renal-artery stenosis (ARAS) and cardiovascular risk. Hypertension develops in patients with renovascular disease from a complex set of pressor signals, including activation of the renin-angiotensin system (RAS), recruitment of oxidative stress pathways, and sympathoadrenergic activation. Although the kidney maintains function over a broad range of autoregulation, sustained reduction in renal perfusion leads to disturbed microvascular function, vascular rarefaction, and ultimately development of interstitial fibrosis. Advances in antihypertensive drug therapy and intensive risk factor management including smoking cessation and statin therapy can provide excellent blood pressure control for many individuals. Despite extensive observational experience with renal revascularization in patients with renovascular hypertension, recent prospective randomized trials fail to establish compelling benefits either with endovascular stents or with surgery when added to effective medical therapy. These trials are limited and exclude many patients most likely to benefit from revascularization. Meaningful recovery of kidney function after revascularization is limited once fibrosis is established. Recent experimental studies indicate that mechanisms allowing repair and regeneration of parenchymal kidney tissue may lead to improved outcomes in the future. Until additional staging tools become available, clinicians will be forced to individualize therapy carefully to optimize the potential benefits regarding both blood pressure and renal function for such patients.

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.

Visceral and Renal Artery Complications of Suprarenal Fixation during Endovascular Aneurysm Repair

BACKGROUND

The effect of suprarenal fixation of endovascular grafts on renal and visceral artery function remains undefined. This study aimed to determine renal and visceral artery complications following suprarenal fixation during endovascular aneurysm repair (EVR).

METHODS

Prospectively collected data from 112 patients who received suprarenal fixation (group SF) and 36 patients who received infrarenal fixation (group IF) in a single institution from December 1997 to April 2005 were reviewed retrospectively. Median follow-up was 26 months (range 0.1-101 months).

RESULTS

Stent struts extended to or above the level of 106 (94.6%) right renal arteries, 104 (92.9%) left renal arteries, 49 (43.8%) superior mesenteric arteries (SMA), and 7 (6.3%) celiac arteries in group SF. This group had 2 (1.8%) unintentional main renal artery occlusions, of which 1 was successfully treated at the first procedure with a renal stent. There was 1 (0.9%) SMA occlusion which resulted in bowel infarction and death. Group IF had no renal or visceral artery complications. There were no late-onset occlusions or infarcts. There was no significant difference in median serum creatinine between groups SF and IF at 1 month (p = 0.18) and 6 months to 12 months (p = 0.22) follow-up. The change in serum creatinine over time was also not significantly different within each group (SF, p = 0.09; IF, p = 0.38).

CONCLUSIONS

In this study, suprarenal fixation was associated with a very small incidence of immediate renal and visceral artery occlusion. There did not appear to be any medium-term sequelae of suprarenal fixation.

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.

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.

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.

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.

Outcomes of accessory renal artery occlusion during endovascular aneurysm repair

OBJECTIVE

Accessory renal arteries are frequently encountered when patients are evaluated for endovascular abdominal aortic aneurysm repair (EVAR). Some have considered their presence a contraindication to EVAR in fear of endoleak and the end result of renal function. We sought to determine whether the coverage of accessory renal arteries during EVAR was associated with any adverse sequelae.

METHODS

Retrospective review of the medical records and computed tomographic scans of all patients undergoing EVAR (1998 to 2003) was performed. Note was made of the presence or absence of accessory renal arteries, hypertension, and renal function. Preoperative computed tomographic images were compared with postoperative images to determine the presence of renal infarction. A control group of 26 consecutive patients without accessory renal arteries was used for comparison of the results of EVAR.

RESULTS

EVAR was performed in 550 patients over the study interval. The mean follow-up was 16 months (range, 1-48 months). The average age was 74 years (range, 57-90 years). Thirty-five patients (6.6%; 32 male and 3 female) were documented to have accessory renal arteries; the average number of accessory arteries was 2 (range, 1-4). Bilateral accessory arteries were present in 13 patients: all but 1 patient (n = 34) had a left-sided accessory renal artery, and 23 had a right-sided accessory renal artery. EVAR was performed with a variety of endografts: AneuRx (n = 10), Talent (n = 7), PowerLink (n = 7), Zenith (n = 5), LifePath (n = 4), and Ancure (n = 2). There were no mortalities. Twelve endoleaks were documented: three type I, eight type II, and one type III. The accessory renal arteries were not implicated in any of the endoleaks, and none of these accessory vessels was embolized before or after EVAR. Seven patients (20%) had renal infarcts associated with EVAR that were noted on follow-up computed tomographic scans. The mean follow-up for patients with segmental infarction was 23 months (range, 8-48 months). Hypertensive status did not change in any patient in whom an accessory renal artery had been covered. The average serum creatinine was 1.08 mg/dL (range, 0.6-1.8 mg/dL) before EVAR in patients with accessory renal arteries covered by an endovascular graft and did not change significantly in response to EVAR. Serum creatinine increased almost twofold in two patients but spontaneously resolved in follow-up. The average preoperative creatinine clearance was 79 mL/min (range, 35-166 mL/min) in patients without an accessory renal artery and was 80 mL/min (range, 35-167 mL/min) after EVAR. The average preoperative creatinine clearance was 67 mL/min (range, 31-137 mL/min) in patients with an accessory renal artery and 68 mL/min (range, 45-83 mL/min) in patients with renal infarcts. None of the patients required temporary or permanent dialysis. There was no difference between control patients and patients with covered accessory renal arteries with respect to hypertensive status, presence of renal infarcts, serum creatinine, or creatinine clearance after EVAR.

CONCLUSIONS

Occlusion of accessory renal arteries is not associated with clinically significant signs or symptoms, even in patients with mild or moderate renal insufficiency. Sacrifice of accessory renal arteries most commonly does not lead to detectable renal infarction, either clinically or radiographically. When segmental infarction of the kidney does result, it seems to be well tolerated in this group of patients. Accessory renal arteries were not found to contribute to endoleaks and should not be prophylactically embolized.

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.

The Management of Abdominal Aortic Aneurysms in Patients with Concurrent Renal Impairment

INTRODUCTION

Patients with concurrent renal impairment and abdominal aortic aneurysms present a significant challenge in terms of pre-operative, intra-operative and post-operative management. This aim of this review was to determine the risks of surgery in this patient group and determine whether any clear management strategies exist to enhance their clinical management.

METHODS

Systematic review of published literature giving details of the outcome of open or endovascular abdominal aortic aneurysm repair in patients with pre-operative renal impairment. Papers concerning the management of post-operative acute renal failure in patients with normal pre-operative renal function has not been included.

RESULTS

There is little data regarding patients with end-stage renal failure and AAA although these patients appear to have a high peri-operative mortality rate. In contrast, those with renal impairment do not have a significantly higher mortality rate than those with normal renal function, rather they have a higher risk of complications associated with surgery and may require more intensive post-operative organ system support than normal patients. Many have a transient deterioration in renal function in the immediate peri-operative period that will resolve. In the case of patients with ruptured AAA, it is not clear whether pre-operative renal impairment affects mortality.

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.

Midterm outcome of endovascular abdominal aortic aneurysm repair in octogenarians: A single institution's experience

OBJECTIVES

We analyzed midterm durability of endovascular abdominal aortic aneurysm repair (EVAR) in octogenarians compared with younger patients.

METHODS

Data for 182 consecutive patients who underwent elective EVAR between 1999 and 2003 were retrospectively reviewed. Forty-nine patients (27%) were 80 years or older (study group [SG]; mean age, 84 years; range, 80-89 years), and 133 patients (73%) were younger (control group [CG]; mean age, 72 years; range, 53-79 years). Chi2 analysis, Fisher exact test, Student t test, and Mann-Whitney U test were used as appropriate to test for intergroup differences. Kaplan-Meier curves, log-rank tests, and multivariate Cox models were used for time-to-event analysis, with P < or =.05 considered significant.

RESULTS

Mean follow-up was 16 months (range, 1-43 months). Body weight was higher (P <.001), and elevated plasma lipid levels (59% vs 43%; P =.042) and use of nicotine (47% vs 29%; P =.015) more frequent in the octogenarians. Baseline aneurysm size, procedure-related data, and hospital stay were comparable between groups. Aneurysm-related mortality was 0% in the study group and 0.7% in the control group (P =.740). Systemic complications occurred in 22% (SG) versus 11% (CG) (P =.035), owing to a rise in serum creatinine concentration greater than 30% of baseline in 14% in the octogenarian group (vs 5% in the CG; P =.048). Groin lymphoceles developed in 12% (SG) versus 2% (CG; P =.013). Technical success was 96% (SG) versus 98% (CG; P =.408), and clinical success was 86% versus 90% (P =.269). No aneurysm rupture occurred during follow-up, and aneurysm-related adverse events were comparable between groups. The estimated risk for any type of endoleak (2.2; 95% confidence interval [CI], 1.1-4.2; P =.023) or type II endoleak (2.1; 95% CI, 1.0-4.3; P = 0.51) was higher in the study group versus the control group; however, this did not affect secondary procedure rates (SG 16% vs CG 12%; estimated risk, SG vs CG,: 1.5; 95% CI, 0.6-3.6; P = 0.420) or aneurysm remodeling (97.2% combined aneurysm sac stabilization or decrease in both groups; P =.592). Aneurysm enlargement occurred in 2.8% (SG 1 vs CG 4; P =.592).

CONCLUSION

Elective EVAR in octogenarians appears safe and effective over midterm follow-up, with a temporary decrease in renal function (14%) and postoperative lymphoceles (12%) being the most common postoperative adverse events. Advanced chronologic age is not associated with diminished procedural outcome, clinical success, or postoperative survival, compared with younger age. Because of low perioperative mortality and high procedural success, EVAR may be the preferred approach to abdominal aortic aneurysm treatment in selected elderly patients.

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.

Diagnostic value of CT virtual intravascular endoscopy in aortic stent-grafting

PURPOSE

To investigate the diagnostic value of postprocessing techniques for 3-dimensional (3D) computed tomography (CT), with emphasis on CT virtual intravascular endoscopy (VIE), in patients with abdominal aortic aneurysms (AAA) treated with suprarenal stent-grafts.

METHODS

The preprocedural and postprocedural CT datasets from 47 AAA patients (40 men; mean age 75 years, range 61-87) undergoing aortic stent-grafting with suprarenal fixation were examined. The CT datasets were processed to create various 3D reconstructions: shaded surface display (SSD), maximum intensity projection (MIP), and VIE. Three independent radiologists assessed various diagnostic parameters for each 3D reconstruction method and compared them to axial CT images.

RESULTS

Scores for VIE reconstructions were inferior to axial CT images in the visualization of normal arterial branches, measurement of the aneurysm diameter and neck length, as well as assessment of vessel patency and presence of endoleaks. VIE was rated superior to axial CT and other 3D imaging methods in visualizing the configuration of stent struts relative to the aortic branch ostia and the number of stent wires crossing the ostia in >80% of cases.

CONCLUSIONS

VIE was not found to play a role in most preoperative situations compared to axial CT images. However, VIE provided additional postgrafting information on the 3D relationship of the suprarenal stent struts to the aortic branch ostia (in particular the renal and superior mesenteric arteries). VIE findings might aid clinicians in accurately assessing the effect of suprarenal stent-grafting on the renal arteries.

Relationship of proximal fixation to postoperative renal dysfunction in patients with normal serum creatinine concentration

OBJECTIVES

This study was performed to determine whether there is deterioration in renal function during follow-up in patients who have undergone endovascular aneurysm repair (EVAR), as recommended by the device manufacturers; to determine whether suprarenal fixation correlates with impairment of renal function; and to explore the potential implication of life-long surveillance of renal function with contrast-enhanced computed tomography.

METHODS

One hundred forty-six consecutive patients underwent EVAR at our institution. Data from 113 of these patients who were free from preoperative renal insufficiency or postoperative renal disease were analyzed. Fifty-three patients received infrarenal (IR) fixation devices, and 60 patients received suprarenal (SR) fixation devices. All SR fixation devices were placed under investigational device exemption protocols. The average follow-up was 688 days. Sixty-five consecutive patients who had undergone open repair of an abdominal aortic aneurysm (AAA) served as the control group.

RESULTS

Preoperative creatinine concentration, intraoperative blood loss, contrast volume, and number of contrast-enhanced procedures were not significantly different between the IR and SR groups. Two renal artery occlusions (1 SR, 1 IR; P=NS) were identified, and 8 renal infarcts (5 SR, 3 IR; P=NS). There was an increase in mean creatinine concentration in the open AAA, IR, and SR fixation groups at each time point in the analysis. Mean elevation in creatinine concentration at 12, 24, and 36 months was 0.10, 0.10, and 0.04 mg/dL, respectively, for open AAA repair; 0.20, 0.21, and 0.28 mg/dL for IR fixation; and 0.15, 0.21, and 0.12 mg/dL for SR fixation. At life table analysis, renal impairment at 36 months was seen in 36% +/- 9% of patients in the IR group, 25% +/- % of patients in the SR group, and 19% +/- 6% of patients in the open AAA group (P=.04 for IR fixation vs open AAA repair).

CONCLUSIONS

A decrease in kidney function is seen after EVAR, regardless of fixation level, that is independent of renal disease and renal arterial occlusion. In patients with normal renal function the site of proximal fixation does not affect postoperative creatinine concentration. The decrease in renal function is likely related to the repetitive administration of contrast agent.

Does transrenal fixation of aortic endografts impair renal function?

OBJECTIVES

Transrenal fixation (TFX) of aortic endografts is thought to increase the risk for renal infarction and impaired renal function. We studied the late effects of TFX on renal function and perfusion.

METHODS

Of 189 patients with commercial aortic endografts, which we inserted between 1995 and 2002, we reviewed data for 130 patients (112 men, 18 women) with available creatinine (Cr) concentration and contrast enhanced computed tomography (CT) scans preoperatively and 1 to 97 months after the procedure. Of the 130 patients, 69 patients had TFX and 61 patients had infrarenal fixation (IFX). Both groups were physiologically comparable. Average age was 76 +/- 8 years for patients with TFX and 75 +/- 8 years for patients with IFX. Presence of renal infarct or renal artery occlusion was determined by nephrograms on serial contrast-enhanced CT scans.

RESULTS

Mean follow-up was 17 +/- 16 months (range, 1-54 months) for TFX and 21 +/- 21 months (range, 1-97 months) for IFX. Mean serum Cr concentration increased significantly during long-term follow-up in both groups (TFX, 1.3 +/- 0.5 mg/dL to 1.5 +/- 0.8 mg/dL, P <.01; IFX, 1.3 +/- 0.7 mg/dL to 1.4 +/- 0.8 mg/dL, P <.03). Creatinine clearance (CrCl) similarly decreased over long-term follow-up in both groups (TFX, 53.3 +/- 17.7 mL/min/1.73 m(2) to 47.9 +/- 16.2 mL/min/1.73 m(2), P <.01; IFX, 58.1 +/- 22.7 mL/min/1.73 m(2) to 53.1 +/- 23.4 mL/min/1.73 m(2), P <.02). There were no significant differences in the increase in Cr concentration (P =.19) or decrease in CrCl (P =.68) between TFX and IFX groups. Small renal infarcts were noted in four patients (5.8%) in the TFX group and one patient (1.6%) in the IFX group. No increase in Cr concentration or decrease in CrCl was noted in any patient with a renal infarct. Postoperative renal dysfunction developed in 7 of 69 patients (10.1%) in the TFX group and 7 of 61 patients (11.5%) in the IFX group. There were no statistically significant differences between groups with respect to number of patients with new renal infarcts (P =.37) or postoperative renal dysfunction (P =.81).

CONCLUSION

There is a slight increase in serum Cr concentration and decrease in CrCl after aortic endografting. However, there was no significant difference in these changes between patients with TFX and IFX. Although TFX may produce a higher incidence of small renal infarcts, these do not impair renal function. Thus our midterm results suggest that TFX can be performed safely, with no greater change in renal function than observed after IFX.

Effect of suprarenal versus infrarenal aortic endograft fixation on renal function and renal artery patency: a comparative study with intermediate follow-up

PURPOSE

Suprarenal fixation of aortic endografts appears to be a safe option in patients with a short or conical proximal aortic neck. However, concern persists regarding the long-term effect on renal function when renal artery ostia are crossed by the uncovered stent. We investigated the effect of suprarenal versus infrarenal endograft fixation on renal function and renal artery patency after endovascular aortic aneurysm repair.

METHODS

Records of 91 patients who underwent endovascular aortic aneurysm repair with a modular bifurcated stent graft between November 1999 and January 2002 were reviewed retrospectively. Two patients receiving dialysis because of chronic renal failure were excluded. Infrarenal fixation was used in 57 patients (group 1), and suprarenal fixation was used in 32 patients (group 2). In two patients in group 1 a Gianturco Z stent was inserted transrenally because of intraoperative proximal type I endoleak, and data for these patients were excluded from analysis. Follow-up evaluation was performed at 1, 6, and 12 months, and yearly thereafter, and included clinical assessment, measurement of serum creatinine concentration (SCr), and computed tomography angiography, per standard protocol. Median follow-up was 12 months (range, 1-36 months).

RESULTS

There was no statistically significant difference in patient demographic data, aneurysm size, or preoperative risk factors. Median SCr was significantly higher in group 2 (suprarenal fixation) than in group 1 (infrarenal fixation) preoperatively (1.2 mg/dL [range, 0.6-2.3 mg/dL] vs 0.9 mg/dL [range, 0.6-1.9 mg/dL], P =.008) and at 1 month postoperatively (1.1 mg/dL [range, 0.8-5.6 mg/dL] vs 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.045). There was a significant increase in median SCr in both groups at 1 month postoperatively (group 1, 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.05; group 2, 1.1 mg/dL [range, 0.8-5.6 mg/dL] [mean SCr, 1.35 mg/dL vs 1.15 mg/dL, respectively], P <.05). In group 1 SCr was increased significantly at 6 and 12 months (P <.001), whereas in group 2 SCr also increased at 6 and 12 months, but not significantly. The change in SCr over time was not significantly different between the two groups. In two of 32 patients in group 2, renal artery occlusion developed, associated with perfusion defects in renal parenchyma and persistently elevated SCr. Analysis of renal artery patency did not demonstrate any association between patency and treatment. No patient developed hypertension during follow-up.

CONCLUSIONS

Suprarenal endograft fixation does not lead to significant renal dysfunction, and renal artery occlusion is uncommon within 12 months. A larger study with longer follow-up is essential to determine overall effects on renal function and renal artery patency.

Transrenal fixation of endovascular stent-grafts for infrarenal aortic aneurysm repair: mid-term results

PURPOSE

We evaluated mid-term results of a single-center consecutive series of endovascular stent-grafts implanted for aortic aneurysm repair with transrenal fixation, to determine clinical outcome, aneurysm anatomy, renal artery patency, and renal complications.

METHODS

Modular stent-grafts were placed with transrenal fixation in 37 patients between November 1998 and July 2000. Follow-up evaluation included clinical examination, laboratory evaluation of serum creatine concentration, computed tomographic angiography, and renal duplex scanning.

RESULTS

Thirty-seven patients underwent transrenal fixation of aortic stent-grafts as part of a Phase II US Food and Drug Administration study. Two patients subsequently underwent follow-up at institutions closer to their homes, and thus provided clinical information but no long-term renal or aneurysm morphologic data. There were no perioperative deaths. Five patients died during follow-up, at a mean of 9 months, because of myocardial infarction in 4 patients and respiratory failure in 1 patient. Thirty patients, ages 75 +/- 8 years, have been followed up for 28.5 +/- 7.2 months. Aneurysm diameter at follow-up was 5.0 +/- 0.8 cm, compared with 5.7 +/- 0.8 cm preoperatively. In 5 patients, endoleak developed during follow-up: 1 type I leak was treated with an aortic cuff, with temporary stabilization of the aneurysm and correction of the endoleak; 2 type II endoleaks were treated with translumbar coil embolization, and 1 resolved spontaneously; and 1 type III endoleak was treated with a combination of coil embolization and stent-graft extension to cover a graft defect. Preoperatively, serum creatinine concentration was normal in 23 patients, but increased persistently in 2 patients and was abnormal in 7 patients. Postoperatively, creatine concentration increased in 4 patients to greater than 20% of baseline level. Seventeen patients had no evidence of renal artery stenosis, compared with 13 patients with renal artery stenosis. Of 41 normal renal arteries, 90% remained unchanged, 1 became occluded, 3 demonstrated 60% stenosis. Nephrectomy was necessary in 1 patient because of cancer. Of 19 abnormal renal arteries, progression of disease was noted in 3 arteries.

CONCLUSIONS

Transrenal fixation of aortic stent-grafts can be performed with acceptable mid-term outcome with respect to mortality, need for follow-up intervention, and aneurysm exclusion with protection from rupture. Postprocedural stenosis can develop in both normal and abnormal renal arteries. Rate of progression of disease was greater in patients with preprocedural renal dysfunction compared with patients with normal renal arteries. This is merely an observation, and may not be related to transrenal fixation. Long-term follow up is needed.