Renal dysfunction and the associated decrease in survival after elective endovascular aneurysm repair

Iodine Assessment of Carbon Dioxide Angiography in Iliac Branched Repair

OBJECTIVE

The objective of this study was to investigate whether the use of carbon dioxide (CO2) angiography decreases the intraoperative use of iodine contrast medium (ICM), thereby decreasing the risk of developing postoperative renal damage in patients undergoing iliac branch device (IBD) implantation.

METHODS

Patients undergoing IBD implantation at a single tertiary center between May 2013 and August 2019 were screened for inclusion in the study. A cohort of patients in whom an intraoperative imaging protocol using predominantly CO2 was compared with a control group in whom ICM was used (CO2 and ICM groups). Fusion imaging was used in both groups. Retrospective review of the medical charts and all imaging was performed. Variables were expressed as median with interquartile range (IQR) or absolute number and percentage. Wilcoxon-Mann-Whitney and χ2 tests were used to compare continuous and categorical variables, respectively. P values of <0 .05 were considered statistically significant.

RESULTS

Twenty-three patients were included in the CO2 group and 21 in the ICM group without significant differences in patient characteristics between the groups. Intraoperative iodine exposure was lower in the CO2 group than in the ICM group (8.2 g [IQR, 7.1-10.9 g) vs 15.8 g (IQR 7.6-21 g); P = 0.015, respectively). There were no differences in technical success, clinical success, fluoroscopy time, and dose-area product in the 2 groups. There were no adverse events that could be related to the intraoperative use of CO2. There was no difference in postoperative survival nor renal function assessment between the groups despite the higher number of accessory renal arteries embolized in the CO2 group (P = 0.221).

CONCLUSIONS

Reduction of intraoperative ICM exposure during IBD implantation is feasible through the predominant use of CO2 automated angiography. This can be done safely without affecting the technical success or radiation exposure. The immediate postoperative renal damage was low when a modern intraoperative imaging protocol with ICM was used and was not significantly reduced by the use of CO2. Further and larger studies are needed to investigate the long-term effects.

CLINICAL IMPACT

This study aimed to investigate how to minimize intraoperative risk during iliac branched repair exploring the intraoperative use of automated carbon dioxide angiography in order to decrease the use of contrast media protecting renal function and thereby potentially impacting long-term survival.

Results of the Italian Collaborators for Evar Registry on Acute Kidney Injury After Elective Endovascular Aortic Repair of Infrarenal Abdominal Aortic Aneurysm

OBJECTIVES

To analyze the incidence and predictive factors of postoperative acute kidney injury (AKI) after elective standard endovascular aortic repair (EVAR) in a large recent, multicenter cohort.

MATERIALS AND METHODS

This is a multicenter, retrospective, financially unsupported physician-initiated observational cohort study. Between January 2018 and March 2021, only patients treated with elective standard EVAR for infrarenal non-infected abdominal aortic aneurysm were analyzed. Patients already on hemodialysis (HD) were excluded. AKI was defined as an increase in serum creatinine (sCr) ≥0.3 mg/dL within 48 hours or an increase in sCr to ≥1.5 times baseline known or presumed to have occurred within 7 days, or a urine volume of <0.5 mL/kg/h for 6 hours. Primary outcomes of interest were AKI incidence at 30 days and freedom from HD at 1-year follow-up. Secondary outcomes were freedom from severe postoperative complication, and freedom from aorta-related mortality (ARM) at 1 year.

RESULTS

The final cohort analyzed 526 (29.8%). There were 489 (93%) males and 37 (7%) females: the median age was 76 years (interquartile range [IQR], 71-81). Chronic kidney disease (CKD) was present in 86 (16.3%) patients. Early mortality was observed in 8 (1.5%) patients, none was aorta-related. Complication rate was 17.1% (n=89). AKI was observed in 17 (3.2%). Renal replacement therapy was needed in 4 (0.8%). HD was transitory in 2 cases and definitive in 1. Binary logistic regression analysis identified CKD (odds ratio [OR]: 4.68, 95% confidence interval [CI]: 2.10-10.45, p<0.001), and the presence of renal artery stenosis (OR: 3.80, 95% CI: 1.35-10.66, p=0.011) to be associated with an increased risk of postoperative AKI. Estimated freedom from ARM was 94.9% at 1 year. Estimated freedom from HD rate at 1 year was 94%: This was significantly different between patients with preoperative CKD and those who did not have preoperative CKD (log-rank, p=0.042).

CONCLUSION

AKI after elective standard EVAR still occurs but with an acceptably low incidence rate. Preoperative CKD is the most important predictor for postoperative AKI, which was not associated with the need for HD at 1-year follow-up but with a higher propensity of mortality.

CLINICAL IMPACT

This "real world" experience confirm that EVAR performed with standard contrats agent protocol remains safe for acute kidney injury development. Therefore, only patients presenting with preoperative borderline or ascertained chronic kidney disease will take the most advantage from the use of carbon dioxide contrast.

Risk Factors for Acute Renal Failure After Endovascular Aneurysm Repair

BACKGROUND

Acute kidney injury (AKI) after endovascular aortic aneurysm repair (EVAR) is uncommon though carries significant morbidity. Procedural risk factors are not well established for acute renal failure (ARF) that requires initiation of dialysis. The goal of this study was to examine the impact of ARF on patients undergoing EVAR and identify risk factors for ARF using a large, national dataset.

METHODS

Patients undergoing EVAR were identified from the National Surgical Quality Improvement Program (NSQIP) database over 9 years, ending in 2019. Demographics, indication for repair, comorbidities, procedural details, complications, hospital and ICU LOS, and mortality were recorded. Patients were stratified by presence of ARF and compared. Patients were further stratified by indication for EVAR and presence of ARF. Multivariable logistic regression (MLR) analysis was performed to determine the independent predictors of ARF.

RESULTS

18 347 patients were identified. Of these 234 (1.3%) developed ARF requiring dialysis. Mortality (40 vs 1.8%, P < .0001), ICU LOS (5 vs 0 days, P < .0001), and hospital LOS (11 vs 2 days, P < .0001) were all significantly increased in patients with ARF. Multivariable logistic regression identified increasing diameter, creatinine, operative time, preoperative transfusions, ASA class, emergent repair, female gender, and juxtarenal/suprarenal proximal landing zone as predictors of ARF.

CONCLUSIONS

ARF after EVAR causes significant morbidity, prolongs hospitalizations, and increases mortality rates. Those patients at risk of ARF after EVAR should be closely monitored to reduce both morbidity and mortality.

A Comparison of Suprarenal and Infrarenal Fixation and Renal Volumetric Analysis after Endovascular Aneurysm Repair

OBJECTIVE

Clinical and experimental studies of the stent-graft fixation impact on renal volume after endovascular abdominal aortic aneurysm repair have focused on glomerular filtration rate (GFR) and the results were controversial. The aim of this study was to analyze and compare the impact of the supra (SRF group) and infra (IRF group) renal stent-graft fixation on the renal volume.

METHODS

Between December 2016 and December 2019, all patients treated with EVAR were retrospectively analyzed. Patients with atrophic or multicystic kidney, renal transplantation, ultrasound or incomplete follow-up were excluded. Renal volume in both groups was extracted with a semi-automatic segmentation from contrast-enhanced CT-scan performed before the procedure, at 1 month and at 12 months follow-up. A subgroup analyze of the SRF group was performed in order to study impact of the stent struts position relative to the renal arteries.

RESULTS

63 patients were analyzed (SRF: 32, IRF: 31). Demographic and anatomical characteristics were similar between the groups. Procedure contrast volume was higher in the IRF group (P= 0.01). At 12-months, the renal volume decreased of 1.4 % in the SRF group and 2.3 % in the IRF group (P=0.86). The SRF sub group analysis showed only 2 patients with no stent struts crossing renal arteries. In the remaining cases, struts crossed one renal artery in 60% of cases (19 patients) and 2 renal arteries in 34% of cases (11 patients). The renal volume decrease was not correlated to the presence of stent wires struts, crossing renal artery.

CONCLUSIONS

Stent-graft with supra renal fixation seems not to be correlated with renal volume deterioration. A randomized clinical trial with a higher effective and longer follow-up is needed to assess the impact of SRF on the renal function.

Investigation of Renal Decline and New Onset Dialysis Following Endovascular Aneurysm Repair in the Vascular Quality Initiative

INTRODUCTION

The purpose of this study is to identify variables significantly associated with renal function decline after elective endovascular infra-renal abdominal aortic aneurysm repair and to identify the rate and risks of subsequent progression to dialysis. Specifically, we investigate the long-term impact of supra-renal fixation, female gender, and physiologically stressful perioperative events on renal function following endovascular aneurysm repair (EVAR).

METHODS

Review of all EVAR cases in the Vascular Quality Initiative between 2003 and 2021 was conducted to investigate variable associations with three primary outcomes: postoperative acute renal insufficiency (ARI); greater than 30% decline in glomerular filtration rate (GFR) in patients beyond 1 year of follow up; and new onset dialysis requirement at any point in follow up. Binary logistic regression analysis was performed for the events of acute renal insufficiency and new onset dialysis requirement. Cox proportional hazard regression was performed regarding long term GFR decline.

RESULTS

Postoperative ARI occurred in 3.4% (1692/49 772) of patients. Significant (P < .05) association with postoperative ARI was noted for: age (OR 1.014/year, 95% CI 1.008-1.021); female gender (OR 1.44, 95% CI 1.27-1.67); hypertension (OR 1.22, 95% CI 1.04-1.44); chronic obstructive pulmonary disease (OR 1.34, 95% CI 1.20-1.50); anemia (OR 4.24, 95% CI 3.71-4.84); reoperation at index admission (OR 7.86, 95% CI 6.47-9.54); baseline renal insufficiency (OR 2.29, 95% CI 2.03-2.56); larger aneurysm diameter; increased blood loss; and higher volumes of intra-operative crystalloid. Risk factors (P < .05) correlating with a decline of 30% in GFR at any time beyond 1 year were: female gender (HR 1.43, 95% CI 1.24-1.65); body mass index (BMI) less than 20 (HR 1.34, 95% CI 1.03-1.74); hypertension (HR 1.38, 95% CI 1.15-1.64); diabetes (HR 1.34, 95% CI 1.17-1.53); COPD (HR 1.21, 95% CI 1.07-1.37); anemia (HR 1.92, 95% CI 1.52-2.42); baseline renal insufficiency (HR 1.31, 95% CI 1.15-1.49); absence of discharge ace-inhibitor (HR 1.27, 95% CI 1.13-1.42); long term re-intervention (HR 2.43, 95% CI 1.84-3.21) and larger AAA diameter. Patients who experienced long term GRF decline had a significantly higher long-term morality. New onset dialysis following EVAR occurred in .47% (234/49 772) of those meeting inclusion criteria. Higher rate (P < .05) of new onset dialysis was associated with age (OR 1.03/year, 95% CI 1.02-1.05); diabetes (OR 1.376, 95% CI 1.005-1.885); baseline renal insufficiency (OR 6.32, 95% CI4.59-8.72); Reoperation at index admission (OR 2.41, 95% CI 1.03-5.67); postoperative ARI (OR 23.29, 95% CI 16.99-31.91); absence of beta blocker (OR 1.67, 95% CI 1.12-2.49); long term graft encroachment on renal arteries (OR 4.91, 95% CI 1.49-16.14).

CONCLUSIONS

New onset dialysis following EVAR is a rare event. Perioperative variables influencing renal function following EVAR include blood loss, arterial injury, and reoperation. Supra-renal fixation is not associated with postoperative acute renal insufficiency or new onset dialysis in long term follow up. Renal protective measures are recommended for patients with baseline renal insufficiency undergoing EVAR as acute renal insufficiency following EVAR portends a 20-fold increased risk of new onset dialysis in long term follow up.

Postoperative Intensive Care Management of Aortic Repair

Vascular surgery patients have multiple comorbidities and are at high risk for perioperative complications. Aortic repair surgery has greatly evolved in recent years, with an increasing predominance of endovascular techniques (EVAR). The incidence of cardiac complications is significantly reduced with endovascular repair, but high-risk patients require postoperative ST-segment monitoring. Open aortic repair may portend a prohibitive risk of respiratory complications that could be a contraindication for surgery. This risk is greatly reduced in the case of an endovascular approach, and general anesthesia should be avoided whenever possible in the case of endovascular repair. Preoperative renal function and postoperative kidney injury are powerful determinants of short- and long-term outcome, so that preoperative risk stratification and secondary prevention are critical tasks. Intraoperative renal protection with selective renal and distal aortic perfusion is essential during open repair. EVAR has lower rates of postoperative renal failure compared to open repair, with approximately half the risk for acute kidney injury (AKI) and one-third of the risk of hemodialysis requirement. Spinal cord ischemia used to be the most distinctive and feared complication of aortic repair. The risk has significantly decreased since the beginning of aortic surgery, with advances in surgical technique and spinal protection protocols, and is lower with endovascular repair. Endovascular repair avoids extensive aortic dissection and aortic cross-clamping and is generally associated with reduced blood loss and less coagulopathy. The intensive care physician must be aware that aortic repair surgery has an impact on every organ system, and the importance of early recognition of organ failure cannot be overemphasized.

Acute Kidney Injury Risk and Contrast Volume in Intact Versus Ruptured Endovascular Aneurysm Repair in the Vascular Quality Initiative

Objective

Renal impairment after repair of ruptured abdominal aortic aneurysm has been associated with post-operative mortality. Acute kidney injury (AKI) risk specifically related to contrast administration in endovascular aneurysm repair (EVAR) for intact vs ruptured aneurysms has not been previously described. It was our objective to evaluate the risk of AKI and the association with contrast administration in EVAR for ruptured (rEVAR) and intact (iEVAR) aneurysm repair in the Vascular Quality Initiative (VQI).

Methods

Adult patients less than 90 years old undergoing EVAR in the VQI without prior abdominal aortic surgery or who were not actively on dialysis preoperatively were included. Patients immediately converted to an open repair were excluded. Patients were grouped by repair urgency, and patient and operative characteristics and outcomes compared. Univariable and multivariable analyses were performed to identify factors associated with the primary outcome of AKI. Survival was evaluated by Kaplan-Meier analysis.

Results

Of 38,775 EVAR patients identified, 86.5% underwent elective surgery for an intact aneurysm, 8.4% had urgent surgery for a symptomatic, intact aneurysm, and 5.1% had emergent repair for a ruptured aneurysm. Significant risk factors for AKI included contrast volume, a preoperative eGFR <30 mL/min, procedure urgency, COPD, congestive heart failure (CHF), and total procedure time. The factor most associated with AKI was aneurysm rupture prior to repair (OR 8.6, CI 7.2-10.3, P <.01). The association of contrast volume with the outcome was the least strong with a 4% increase in risk per 25 mL of contrast (OR 1.04, 95% CI 1.01-1.07). With the development of AKI, postoperative survival was reduced regardless of indication.

Conclusions

Of all factors assessed, aneurysm rupture was the most and contrast volume the least associated with AKI after EVAR. Further studies should evaluate methods of preventing post-EVAR AKI.

Open Abdominal Aortic Aneurysm Surgery and Renal Dysfunction; Association of Demographic and Clinical Variables with Proximal Clamp Location

BACKGROUND

While cross-clamp site is a known risk factor for postoperative acute and chronic renal dysfunction following open abdominal aortic aneurysm surgery (AAA), the additive impact of patient demographic and clinical factors is lacking. In this study, we investigated the impact of body mass index (BMI), surgical duration and aneurysm diameter on the association between proximal cross-clamp location and postoperative renal dysfunction.

METHODS

In this study, we conducted a retrospective analysis of 4,197 patients undergoing open AAA surgery between 2011 and 2018 using data housed in the American College of Surgeons National Safety Quality Improvement Program (ACS-NSQIP) database. The primary outcome was renal dysfunction, which was defined as patients requiring dialysis within 30 days or patients with ≥2 mg/dL rise in creatinine from baseline. We assessed the incidence of renal dysfunction with regard to clamp location and subsequently used multivariable logistic regression to assess clinical and demographic factors associated with renal dysfunction. We used a regression model to plot the association of BMI, surgical duration, and aneurysm diameter with an adjusted probability of postoperative acute and chronic renal dysfunction for individual cross-clamp locations.

RESULTS

Of the 4,197 patients analyzed, 405 patients (9.6%) developed renal dysfunction within 30 days with 287 patients requiring dialysis. Patients with supraceliac clamp location had the highest incidence of renal dysfunction (20.4%). Our data showed a significant association of renal dysfunction with higher BMI patients [OR 1.04 (1.02, 1.07), P = 0.001], longer operative times [OR1.01 (1.01, 1.02), P < 0.001], clamp location between the superior mesenteric artery (SMA) and renal artery [OR 1.80 (1.17, 2.78), P = 0.007] and supraceliac clamp location [OR 2.47 (1.62, 3.76), P < 0.001].

CONCLUSIONS

The incidence of renal dysfunction increases with suprarenal clamps. Patients with higher BMI, longer operative times, and increasing aneurysm diameter, and a suprarenal clamp have a significantly increased risk of renal dysfunction compared to those who also had a suprarenal clamp but lower BMI, shorter operative times and smaller aneurysm diameter.

CO2 Automated Angiography in Endovascular Aortic Repair Preserves Renal Function to a Greater Extent Compared with Iodinated Contrast Medium. Analysis of Technical and Anatomical Details

BACKGROUND

Contrast induced nephropathy occurs in up to 7.5% of cases in endovascular aortic repair (EVAR). Carbon dioxide (CO₂) has been proposed as an alternative agent to iodinated contrast medium (ICM); however, specific protocols are not universally adopted, and the visualization of the renal arteries may be suboptimal in some cases. The aim of this study was to analyze our CO₂-EVAR experience with automatic injections, in order to identify the anatomical characteristics associated with the best visualization of all the aortic vessels, with particular attention to the lowest renal artery (LoRA).

METHODS

From 2016 to 2019, all EVAR performed with either CO₂ or ICM were analyzed and compared. CO₂-EVAR was performed using an automated injector (600 mm Hg pressure; 100 cc volume); a small amount of ICM was injected in case of difficulty in LoRA visualization or doubts at the completion angiogram. Clinical and CT-Scan preoperative characteristics were considered. The study endpoints were technical success, amount of ICM and radiation dose, postoperative renal function and possible CO₂-related adverse events. Statistical analysis was by Fisher's exact, t-Student, Mann-Whitney tests and ROC curve.

RESULTS

In the considered period, 321 EVAR procedures, 72 (22.4%) with CO₂ and 249 (77.6%) with ICM, were performed. The 2 groups were similar for clinical characteristics and preoperative renal function. ICM was injected in a significantly lower amount in the CO₂-EVAR group (52.8 ± 6.1 vs. 88.1 ±9.2 cc, P < 0.001), which received a significantly higher mean radiation dose (Total DAP: 500,550.8 ± 377,394.6 mGy/cm² CO₂-EVAR vs. 332,301.8 ±230,139.3 mGy/cm² ICM-EVAR, P = 0.001). Postoperative eGFR decreased significantly less in the CO₂-EVAR (2.3 ± 1.1 mL/min) compared with the ICM-EVAR group (10.6 ±5.3 mL/min), P < 0.001. LoRA was correctly visualized in 50/72 (69.4%) cases of CO₂-EVAR, which had a significantly longer proximal neck (Median [IQR]: 30 [14] vs. 18 [15] mm, P = 0.001). At ROC curve, a proximal neck length >24.5 mm was predictive of LoRA visualization (72.1% sensitivity, 73.8% specificity). Three CO₂-EVAR cases had intraoperative transient hypotension with no consequences. Sixteen/72 (22.2%) CO₂-EVAR procedures were performed using 0 cc of ICM.

CONCLUSIONS

CO₂-EVAR by automated injections is safe and requires a lower amount of ICM if compared with ICM-EVAR, with a consequent significant benefit on postoperative renal function. If specific anatomical situations are present, ICM may be completely unnecessary. The radiation dose is however significantly higher, therefore procedural protocols need further refinements.

Multicenter Mid-Term Outcomes of the Chimney Technique in the Elective Treatment of Degenerative Pararenal Aortic Aneurysms

PURPOSE

Chimney endovascular abdominal aortic aneurysm repair (CHEVAR) has predominantly been described as an alternative technique for the management of urgent presentations of degenerative pararenal aortic aneurysms (dPAAs). However, the role of CHEVAR in the treatment of asymptomatic patients remains unknown. The aim of current multinational study was to evaluate the outcomes of elective CHEVAR of dPAAs.

MATERIAL AND METHODS

Retrospective analysis of 267 consecutive dPAA patients treated with elective CHEVAR at 13 European and US centers from 2008 to 2014. Primary endpoints were 30 days and out of hospital CHEVAR-related mortality. Secondary endpoints included persistent type Ia endoleak or endotension, angiographically confirmed occlusion and/or high-grade chimney graft (CG) or involved splanchnic vessel stenosis identified at index procedure and/or during follow-up, as well as CHEVAR-related re-intervention.

RESULTS

Mean follow-up time was 25.5±13.3 months. The 442 visceral vessels were involved and mean number of CGs per patient was 1.63±0.7. 436 targeted vessels were successfully cannulated. The aortic graft intentionally covered 6 renal arteries and immediate technical success was 98.6%. The 30 days mortality was 1.9% (n=5), while the in-hospital complication rate was 10.1% (n=27) including 3 strokes, 1 permanent dialysis, and 1 intestinal ischemia. No 30 day type Ia endoleaks were detected and 3.2% of CGs (n=14, including the intentionally covered) had evidence of occlusion and/or stenosis. The overall CHEVAR-related mortality was 2.2% (n=6). Freedom from primary and secondary type Ia endoleak/endotension rates at 3 years was 93.0% and 98.0%, respectively. Primary and secondary CG patency was 87.0% and 89.0%. Primary and secondary endovascular freedom from any endpoint at 3 years was 81.0% and 94.0% respectively.

CONCLUSION

Elective use of CHEVAR in the management of dPAAs seems to be durable. These results are comparable to published outcomes with other total endovascular strategies, which justifies an expanded role for CHEVAR in the treatment of asymptomatic patients presenting with dPAAs.

Dexmedetomidine reduces acute kidney injury after endovascular aortic repair of Stanford type B aortic dissection: A randomized, double-blind, placebo-controlled pilot study

STUDY OBJECTIVE

To determine the effect of dexmedetomidine on acute kidney injury (AKI) following endovascular aortic repair (EVAR) for Stanford type B aortic dissection (TBAD).

DESIGN

Randomized, double-blind, placebo-controlled, pilot study.

SETTING

University Hospital.

PATIENTS

102 TBAD patients undergoing EVAR procedures were enrolled. Patients with dissection involving aortic arch or renal artery were excluded.

INTERVENTIONS

Patients were randomly assigned, in a 1:1 ratio, to a dexmedetomidine group (intravenous dexmedetomidine 0.4 μg/kg/h immediately after anesthesia induction and 0.1 μg/kg/h after extubation, which was maintained until 24 h) or a normal saline control group.

MEASUREMENTS

The primary outcome was the incidence of AKI within the first two days after surgery, based on the Acute Kidney Injury Network (AKIN) criteria. The secondary outcomes included serum cystatin C and estimated glomerular filtration rate on postoperative days 1, 2, and 7, and in-hospital need for renal replacement therapy (RRT). Long-term outcomes included RRT and all-cause mortality.

MAIN RESULTS

Ninety-eight patients completed the study (dexmedetomidine, n = 48; control, n = 50). AKIN stage 1 AKI occurred in 3/48 (6.3%) patients receiving dexmedetomidine, compared with 11/50 (22%) patients receiving normal saline (odds ratio = 0.24, 95% CI: 0.07 to 0.89, P = 0.041). This difference remained significant after adjusting for baseline covariates (adjusted odds ratio = 0.21, 95% CI: 0.05 to 0.84; P = 0.028). Dexmedetomidine led to a lower serum cystatin C on postoperative day 1 (median [IQR] mg/L: 1.31 [1.02-1.72] vs. 1.58 [1.28-1.96]). There were no between-group differences in other secondary or long-term outcomes. During the follow-up (median = 28.4 months), 1 patient in the dexmedetomidine group and 3 patients in the control group required RRT.

CONCLUSIONS

Dexmedetomidine reduced the incidence of AKI in TBAD patients after EVAR procedures. The long-term benefits of dexmedetomidine in this patient population warrant further investigation.

TRIAL REGISTRATION

ChiCTR-IPR-15006372.

Rapid endovascular bailout revascularization of the renal arteries with a steerable guiding sheath after endovascular abdominal aortic aneurysm repair

Advancements in endovascular therapy have made it increasingly available for patients with complex cases but not without complications. Unintentional coverage of the renal arteries is a rare occurrence during endovascular aortic aneurysm repair. Given the potentially devastating repercussions, it is important that surgeons understand the suitability and the risks and benefits of the available revascularization options. We have described two cases of unintentional renal coverage, with subsequent successful bailout via direct manipulation of the stent-graft with a steerable sheath. We also conducted a review of the reported data, discussed the breadth of management options and their technical aspects, and provided several distinct solutions.

Poor concordance of contemporary performance measures in detecting complications in complex endovascular aortic repair

BACKGROUND

The Agency for Healthcare Research and Quality Patient Safety Indicators (PSI) are quality improvement indicators used to determine hospital performance and, increasingly, to rank surgical programs. The American College of Surgeons National Surgical Quality Improvement Program and the Society for Vascular Surgery Vascular Quality Improvement databases are also frequently used to compare outcomes, but definitions of complications vary between the systems and the optimal system for tracking complications in complex endovascular repair remains unclear. Herein we assess the three outcome tracking systems and their ability to capture complications after fenestrated endovascular abdominal aortic aneurysm repair (FEVAR) and open aortic aneurysm repair in a large complex aortic program.

METHODS

Demographic and operative data for patients undergoing repair of juxtarenal or pararenal aortic aneurysms between 2004 and 2018 via both open and FEVAR approaches at the Johns Hopkins Medical Institutions were compiled in a prospectively maintained retrospective database. Postoperative complications were defined according to a surgeon-defined system, the Society for Vascular Surgery Vascular Quality Initiative, the American College of Surgeons National Surgical Quality Improvement Program, and the Agency for Healthcare Research and Quality PSI data dictionaries and were compared between surgical approaches as well as eras before and after the introduction of FEVAR. Complication rates between the classification systems were compared using proportion testing and the strength of the correlation between the systems was evaluated with Spearman's rank test.

RESULTS

Of 145 patients, 60 (41.4%) underwent FEVAR and 85 (58.6%) underwent open aortic aneurysm repair. The introduction of fenestrated technology was associated with a decrease in the overall number of complications from 37.2% to 20.6% by surgeon-defined classification system (P = .036). The VQI identified the most complications (39.9% of the entire cohort and 25% of FEVAR cases), followed by the NSQIP (29.0% and 33.3%, respectively) and PSI (4.1% and 5%). The two clinically focused databases were found to correlate well with a surgeon-designed classification system, as well as each other (Spearman ρ ≥ 0.735) but not with PSI (ρ < 0.23). Proportion testing demonstrated the rate of complications identified by PSI to be significantly less than either VQI or NSQIP (P < .001). Specifically, PSI did not effectively identify renal complications (1.4% vs 9.0% by NSQIP and 27.3% by VQI definitions; P < .001).

CONCLUSIONS

The introduction of FEVAR is associated with an overall decrease in complications in this study. The clinically relevant VQI and NSQIP databases show good concordance in capturing complications; however, PSI did not correlate with either and captured significantly fewer complications. These data highlight the value of high scrutiny classification systems to track postoperative complications and suggest that PSI are insufficient to rank complex aortic programs with high levels of FEVAR use.

Clinical effect of accessory renal artery coverage after endovascular repair of aneurysms in abdominal and thoracoabdominal aorta

BACKGROUND

The aim of our systematic review and meta-analysis was to assess the effect of accessory renal artery (ARA) coverage on renal function in terms of acute kidney injury (AKI), renal infarction, chronic renal failure (CRF), and mortality in patients undergoing standard endovascular aortic aneurysm repair (EVAR) or endovascular repair of complex aneurysms.

METHODS

An electronic search of the English language medical literature from 2000 to September 2020 was conducted using the MEDLINE, EMBASE, and Cochrane databases with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) method for studies reporting on ARA management in patients undergoing endovascular repair of aneurysms in the abdominal and thoracoabdominal aorta. The patients were divided into two groups: group 1, patients with ARA coverage; and group 2, patients without an ARA or without coverage of the ARA. Each group included two arms, one of patients who had undergone standard EVAR and one of patients who had undergone endovascular treatment of a complex aortic aneurysm. The GRADE (grading of recommendations assessment, development, evaluation) approach was used to evaluate the quality of evidence and summary of the findings. The primary outcomes included the incidence of AKI, renal infarction, CRF, and mortality.

RESULTS

Ten retrospective, nonrandomized, control studies were included in the systematic review reporting on 1014 patients (302 with a covered ARA vs 712 without an ARA or without ARA coverage). In six studies, the mean diameter of the covered ARA was <4 mm (range, 2.7-3.4 mm). The mean follow-up was 22.74 months (range, 1-42 months). In the standard EVAR subgroup, the risk of AKI (odds ratio [OR], 0.72; 95% confidence interval [CI], 0.21-2.51; I² = 0%] in the early period, and CRF (OR, 4.44; 95% CI, 0.46-42.61; I² = 87%) and death (OR, 0.91; 95% CI, 0.36-2.31; I² = 0%) during follow-up were similar between groups 1 and 2. Only the risk of renal infarction was greater in group 1 than in group 2 (OR, 93.3; 95% CI, 1.48-5869; I² = 92%). In the complex aneurysm repair subgroup, the risk of AKI (OR, 1.85; 95% CI, 0.61-5.64; I² = 42%) in early period and CRF (OR, 1.64; 95% CI, 0.88-3.07; I² = not applicable) and death (OR, 3.63; 95% CI, 0.14-96.29; I² = 56%) during follow-up were similar between groups 1 and 2. Only the risk of renal infarction was greater for group 1 compared with group 2 (OR, 8.58; 95% CI, 4.59-16.04; I² = 0%).

CONCLUSIONS

ARA (<4 mm) coverage in patients undergoing standard EVAR or endovascular repair of complex aneurysms is associated with an increased risk of renal infarction. However, we found no clinical effects of ARA coverage on renal function or mortality in early postoperative and follow-up period. Preservation of an ARA >4 mm should be considered.

Kidney-Specific Klotho Gene Deletion Causes Aortic Aneurysm via Hyperphosphatemia

[Figure: see text].

Renal function-adjusted contrast medium volume is a major risk factor in the occurrence of acute kidney injury after endovascular aneurysm repair

Acute kidney injury (AKI) is a complication that can occur during endovascular aneurysm repair (EVAR), increasing postoperative mortality and disease-related death. We therefore evaluated the incidence of AKI after elective EVAR, as well as related factors affecting AKI occurrence, investigating the volume of contrast medium (CV)/estimated glomerular filtration rate (eGFR) ratio as a predictive factor.We retrospectively reviewed the data of patients who underwent EVAR for infrarenal abdominal aorta aneurysm at a single center between April 2011 and December 2018. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria. We evaluated the occurrence of AKI within the first 7 days postoperatively, comparing serum creatinine levels, eGFR, CV, CV/eGFR ratio, fluid input and output, and morbidity between the AKI and no-AKI groups.The data of 147 patients were analyzed, of which 131 (89.1%) were males (mean age: 72.10±7.40 years); the incidence of AKI was 4.1% (6/147 patients). The mean dose of contrast agents used was greater in the AKI group than in the no-AKI group (249.17 ± 83.21 mL vs 179.43 ± 84.32 mL, respectively; P = .05). The baseline eGFR was 42.69 ± 22.08 mL/kg/1.73 m2 in the AKI group and 77.96 ± 18.92 mL/kg/1.73 m2 in the no-AKI group (P = .001). The CV/eGFR ratio was significantly higher in the AKI group (8.21 ± 6.13 vs 2.46 ± 1.44; P = 0.003). Baseline eGFR (odds ratio [OR] = 0.922, P = .001) and the CV/eGFR ratio (OR = 2.049, P = .008) were observed to be factors related to the occurrence of AKI in the logistic regression analysis for patients' characteristics, operation-related factors, and renal outcomes. In the receiver operating characteristic curve analysis, the area under the curve of the CV/eGFR ratio was 0.856, indicating the greatest influence. A CV/eGFR ratio cutoff value of 3.84 was considered the most appropriate, with an 83.3% sensitivity and 83.0% specificity.The CV/eGFR ratio, rather than the absolute amount of contrast agents, was associated with the development of AKI after EVAR. The CV/eGFR ratio could be used as a possible indicator to limit the amount of contrast media required for the procedure.

Risk of renal failure and death when renal arteries are involved in endovascular aortic aneurysm repair

OBJECTIVE

Endovascular abdominal aortic repair can involve the incorporation of renal arteries. Revascularization after intentional or unintentional renal artery (RA) coverage is not always technically successful, and the loss of a single RA may result in the need for postoperative dialysis. Thus, we compared the outcomes after endovascular aneurysm repair (EVAR) stratified by RA involvement (RAI).

METHODS

Patient data from the Vascular Quality Initiative from 2009 to 2018 registry were analyzed. The exclusion criteria were preoperative dialysis, missing RAI data, and repair above the superior mesenteric artery. The repair type cohorts were defined as (1) no RAI (NRAI), (2) RAI with revascularization (RAI-R), and (3) RAI with no revascularization (RAI-NR). A sensitivity analysis was performed by excluding ruptured presentations. The primary outcome was the need for postoperative dialysis. The secondary outcomes were 30-day mortality, dialysis at follow-up, postoperative renal function, and 2-year survival. Multivariate analysis was used to determine the independent predictors for postoperative dialysis. The 2-year survival analysis was performed using Kaplan-Meier log-rank test.

RESULTS

Of 54,020 patients in the EVAR and TEVAR (thoracic EVAR)/complex EVAR modules in the Vascular Quality Initiative, 25,724 met the criteria for inclusion (NRAI, n = 24,879; RAI-R, n = 733; RAI-NR, n = 112). The demographics and comorbidities were similar among the three groups. The RAI-NR group had more frequently had ruptured or symptomatic aneurysms. The postoperative dialysis requirement was higher in the RAI-NR group (NRAI, 0.7%; RAI-R, 2.2%; RAI-NR, 17%; P < .0001), as were the 30-day mortality and dialysis requirement at follow-up. On multivariate analysis, RAI-R (odds ratio [OR], 2.2; P = .03) and RAI-NR (OR, 5.9; P < .0001) were independent predictors of postoperative dialysis and remained so after excluding ruptured presentations (RAI-R: OR, 3; P = .003; RAI-NR: OR, 22.3; P < .0001). Other independent predictors of the need for postoperative dialysis were worse preoperative renal function, a symptomatic presentation, any preoperative or intraoperative blood transfusion, and larger blood loss (≥200 mL). Excluding those with rupture, the overall survival at 2 years on Kaplan-Meier analysis was lower for the RAI-NR group (NRAI, 92%; RAI-R, 89%; RAI-NR, 80%; P = .004).

CONCLUSIONS

RAI is highly predictive of the need for postoperative and permanent dialysis after EVAR. RAI-NR was associated with lower overall survival. These risks should be considered when planning and performing EVAR and should be weighed against the risks of open repair when considering the treatment options.

Endovascular Infrarenal Aortic Aneurysm Repair Performed in a Hybrid Operating Room Versus Conventional Operating Room Using a C-Arm

BACKGROUND

To compare contrast usage and radiation exposure during endovascular aneurysm repair (EVAR) using mobile C-arm imaging in a conventional operating room (OR) or fixed angiographic equipment in a hybrid OR (HR).

METHODS

A retrospective unicenter study from May 2016 to August 2019. All consecutive patients undergoing standard EVAR were included. Patients were divided into 2 groups. Group OR included EVARs performed in a conventional OR with a mobile C-arm (May 2016 to April 2018) and group HR included EVARs performed with a fixed angiographic equipment in an HR (May 2018 to August 2019). Data collected included patient demographics, aneurysm diameter, neck length, radiation dose: median dose-area product (DAP), fluoroscopy time, total operative time, contrast use, and 30-day clinical outcomes.

RESULTS

A total of 77 patients were included in the study (42 patients in group OR and 35 patients in group HR). There was no difference in age, body mass index (BMI), mean aneurysm, and neck length between groups. Patients in the group HR received less contrast volume (108.6 mL [±41.5] vs. 162.5 mL [±52.6]; P < 0.001), but higher radiation dose (154 Gy cm² [±102.9] vs. 61.5 Gy cm² [±42.4]; P < 0.001). There were no differences in fluoroscopy time (20.4 min [±8.5] vs. 23.2 min [±12.4]; P = 0.274) and total operative time (106.4 [±22.3] vs. 109.4 [±25.8]; P = 0.798). No difference was found in terms of 30-day complication rates or operative mortality between groups. DAP was positively correlated with BMI in the group OR (Spearman's rank correlation coefficient r_s, 0.580; P < 0.001), but no correlation could be seen in the group HR (r_s, 0.408; P = 0.028).

CONCLUSIONS

Routine EVAR performed in a hybrid fixed-imaging suite may be associated with less contrast usage, but higher radiation exposure in our center. The significantly higher radiation exposure when the mobile C-arm is replaced by an HR should not be underestimated.

Renal Dysfunction Following Elective Endovascular Aortic Aneurysm Repair

Abdominal aortic aneurysm (AAA) is a degenerative disease of the aortic wall with potentially fatal complications. Open repair (OR) was considered the gold standard, until the emergence of endovascular aneurysm repair (EVAR), which is less invasive and equally (if not more) effective. As the popularity of endovascular procedures grows, related complications become more evident, with kidney damage being one of them. Although acute kidney injury (AKI) following EVAR is relatively common, its true incidence is still uncertain. Also, there is insufficient data concerning long-term renal outcomes after EVAR, especially with repeated contrast agent exposure. Despite the lack of firm evidence on the effectiveness of individual strategies, it is evident that prevention of AKI following EVAR requires a multifactorial approach. This review focuses on recent findings based on human studies regarding the current evidence of renal impairment after EVAR, its quantification and strategies for its prevention.

Acute Renal Failure/Acute Kidney Injury (AKI) Associated with Endovascular Procedures

AKI is one of the most common yet underdiagnosed postoperative complications that can occur after any type of surgery. Contrast-induced nephropathy (CIN) is still poorly defined and due to a wide range of confounding individual variables, its risk is difficult to determine. CIN mainly affects patients with underlying chronic kidney disease, diabetes, sepsis, heart failure, acute coronary syndrome and cardiogenic shock. Further research is necessary to better understand pathophysiology of contrast-induced AKI and consequent implementation of effective prevention and therapeutic strategies. Although many therapies have been tested to avoid CIN, the only potent preventative strategy involves aggressive fluid administration and reduction of contrast volume. Regardless of surgical technique—open or endovascular—perioperative AKI is associated with significant morbidity, mortality and cost. Endovascular procedures always require administration of a contrast media, which may cause acute tubular necrosis or renal vascular embolization leading to renal ischemia and as a consequence, contribute to increased number of post-operative AKIs.

Acute Kidney Injury Following Elective Open Aortic Repair with Suprarenal Clamping

Objective: To investigate predictors of acute kidney injury (AKI) following open aortic repair (OAR) requiring suprarenal clamping.

Methods: The study included 833 nonhemodialysis patients who had undergone elective OAR (with suprarenal clamping, n=73; with infrarenal clamping, n=760). We evaluated AKI as defined by the criteria of the Kidney Disease Improving Global Outcomes (KDIGO) and compared in-hospital outcomes between the two groups. We also investigated the effects of AKI on outcomes, factors related to post-suprarenal clamping AKI, and efficacy of hypothermic renal perfusion (HRP) in the suprarenal clamping group.

Results: For the suprarenal vs. infrarenal clamping group, in-hospital mortality was 0% (0/73) vs. 0.5% (4/760). The incidence of AKI was greater in the suprarenal clamping group (37% vs. 15%, P<0.001), and the hospital stay for patients with AKI was longer than for those patients without AKI (median, 21 days vs. 16 days; P=0.005). Renal ischemia time and bleeding volume >1,000 mL were associated with post-suprarenal clamping AKI. Renal ischemia time was longer with HRP (n=15) than without HRP (n=58) (median, 51 min vs. 33 min; P=0.011), and HRP did not decrease the incidence of AKI (40% vs. 36%; P=0.78).

Conclusion: Prolonged renal ischemia and substantial intraoperative bleeding are associated with postoperative AKI following suprarenal clamping.

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.

Results from a prospective multicenter feasibility study of Zenith p-Branch stent graft

OBJECTIVE

To evaluate the Cook Zenith p-Branch stent graft (William A. Cook Australia, Brisbane, Queensland, Australia) for the treatment of patients with asymptomatic juxtarenal or pararenal abdominal aortic aneurysms in a prospective, nonrandomized, multicenter, feasibility study conducted in the United States.

METHODS

The off-the-shelf p-Branch endograft incorporates a celiac scallop, superior mesenteric artery (SMA) fenestration, and two conical-shaped pivot renal fenestrations. Patients were eligible if the aneurysm did not extend above the distal margin of the SMA and the anatomy of renal and visceral arteries were compatible with one of the two p-Branch configurations (configuration A, renal fenestrations at the same longitudinal position; configuration B, offset renal fenestration).

RESULTS

A total of 30 patients (93% men; mean age, 73 years; mean aneurysm diameter, 64.7 ± 11.4 mm) were enrolled from January 2013 to June 2015. The mean follow-up period was 28.7 ± 12.5 months (as of October 2017). The technical success rate was 93% (28/30), with technical failure occurring in the first two study cases (device deliberately repositioned below the renal arteries because of difficulty in cannulating the renal arteries in one and an inability to place a renal stent in the other; both patients survived the procedure and withdrew from the study before the 12-month follow-up visit). No additional technical failures occurred after these first two cases, when an updated physician training and proctoring program was implemented. No 30-day mortality occurred. Of the remaining 28 patients, three died during the follow-up period; none within 30 days and none related to the device or procedure as determined by Clinical Events Committee adjudication. No treated aneurysm ruptures, conversion, or core laboratory-reported migration, or stent fracture were reported. The primary renal artery patency (interval to occlusion or reintervention for stenosis) rate was 88.6% ± 4.4% at 1 and 2 years. Two patients (7%) developed renal insufficiency secondary to a right renal artery stenosis in one patient and progression of chronic renal insufficiency in one patient. No patient required dialysis or developed mesenteric ischemia. Of the 28 patients, nine (32%) had undergone 13 secondary interventions for renal artery occlusion (n = 2), SMA occlusion (n = 1), renal or SMA stenosis (5 interventions in 4 patients), renal stent kinking (n = 1), lower extremity claudication (n = 2 in the same patient), type III endoleak between the p-Branch and renal stent (n = 1), and type II endoleak (n = 1).

CONCLUSIONS

These early and intermediate results, which incorporated physician learning curves, support the safety and feasibility of the off-the-shelf Zenith p-Branch device. Follow-up examinations through 5 years will continue to assess the long-term results.

Predictors of in-hospital adverse events after endovascular aortic aneurysm repair

BACKGROUND

Endovascular aneurysm repair (EVAR) offered outstanding survival benefit but at the expense of cost, periodic radiographic monitoring, and higher reinterventions rates. Perioperative complications, although rare, can occur after EVAR, contributing to longer hospitalization, higher cost, and significant comorbidity and mortality. Therefore, the aim of this study was to identify the predictors of in-hospital events (IHEs) after elective EVAR.

METHODS

The Vascular Quality Initiative database was explored from 2003 to 2017. Patients who had converted to open repair were excluded. IHEs were defined as any in-hospital myocardial infarction, dysrhythmia, congestive heart failure (CHF), stroke, pneumonia, respiratory failure, renal failure, lower extremity ischemia, bowel ischemia, or reoperation. Stepwise backward selection based on the Akaike information criterion statistic was implemented to select the predictors of IHE from the multivariable logistic regression models. Bootstrapping was performed with 1000 replications to internally validate the model and to obtain bias-corrected estimates. Receiver operating characteristic curves (area under the curve [AUC]) and Hosmer-Lemeshow tests were used to assess the discrimination and calibration of the models.

RESULTS

A total of 28,240 patients with full information about IHEs were included. Any IHE took place in 2365 (8.4%) patients. Patients who had an IHE were slightly older (mean age ± standard deviation, 75.6 ± 8.1 years vs 73.3 ± 8.5 years; P < .001]. A higher proportion of women had an IHE (25.6% vs 17.9%; P < .001). Comorbid conditions were more prevalent in patients who developed an IHE (chronic kidney disease, 49.1% vs 33.2%; coronary artery disease, 34.3% vs 29.0%; moderate to severe CHF, 3.9% vs 1.4%; chronic obstructive pulmonary disease, 42.5% vs 31.9%; hypertension, 87.0% vs 83.1%; and diabetes, 18.0% vs 16.1%; all P ≤ .015). An IHE was associated with high in-hospital (5.6% vs 0.03%) and 30-day mortality (6.3% vs 0.3%; both P < .001) and worse 3-year survival beyond the perioperative period (81.1% [79.3%-82.9%] vs 91.1% [90.7%-91.5%]; P < .001). Two models were constructed, one from preoperative factors and the second from preoperative and intraoperative factors. The selected predictors of IHEs were female sex, moderate or severe CHF, chronic kidney disease, coronary artery disease, chronic obstructive pulmonary disease, hypertension, and aneurysm diameter. Intraoperative factors were contrast material volume, operative time, and packed red blood cell transfusion. Nomograms were constructed from the final models. AUC significantly improved after adding intraoperative factors (AUC [95% confidence interval], 0.71 [0.70-0.73] vs 0.65 [0.64-0.66]; P < .001].

CONCLUSIONS

In-hospital adverse events can complicate the perioperative course of EVAR and increase the risk of operative and long-term mortality. Predicting IHEs and identifying their risk factors can potentially mitigate their development in patients at high risk. Predicting IHE risk can have tremendous prognostic value and help disposition planning. This study introduces an internally validated tool to enable vascular surgeons to identify patients' chance of having an IHE.

Effects of Ischemic Preconditioning on Abdominal Aortic Aneurysm Repair: A Systematic Review and Meta-analysis

BACKGROUND

Ischemic preconditioning is an innate mechanism of cytoprotection against ischemia, with potential for end-organ protection. The primary goal of this study was to systematically review the literature to determine the effect of ischemic preconditioning on outcomes after open and endovascular abdominal aortic aneurysm (AAA) repair.

METHODS

The methodology followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. We included randomized clinical trials that evaluated the effect of remote ischemic preconditioning (RIPC) in reducing morbidity and mortality in patients undergoing open or endovascular AAA repair surgery. The primary outcomes were death, myocardial infarction, and renal impairment. Outcomes were addressed separately for open AAA repair and endovascular AAA repair (EVAR). Data were collected on patient characteristics, methodology, and preconditioning protocol for each trial.

RESULTS

Nine trials of ischemic preconditioning in aortic aneurysm surgery were included with a total of 599 patients; 336 patients were included in the open AAA repair meta-analysis, and 263 patients were included in the EVAR meta-analysis. For both open and endovascular repairs, ischemic preconditioning did not have a significant effect on death, myocardial infarction, or renal impairment requiring dialysis.

CONCLUSIONS

The randomized clinical trials investigating the effect of ischemic preconditioning on outcomes after open and endovascular AAA repair that have been completed to date have not been adequately powered to evaluate improvements in patient-important outcomes. The evidence is insufficient to support the use of ischemic preconditioning for AAA repair in clinical practice. The variability in treatment effect across studies may be explained by clinical and methodological heterogeneity.

Predictors of Acute Kidney Injury Following Elective Open and Endovascular Aortic Repair for Abdominal Aortic Aneurysm

Objective: To investigate the predictors of acute kidney injury (AKI) following surgery for abdominal aortic aneurysm.

Materials and Methods: Subjects were 642 non-hemodialysis patients (open aortic repair [OAR] group, n=453; endovascular aortic repair [EVAR] group, n=189) who underwent elective surgery between 2009 and 2015. AKI was assessed according to the Kidney Disease Improving Global Outcomes criteria. In-hospital mortality and incidence of AKI were compared between the OAR and EVAR groups. The effect of AKI on outcomes and predictors of AKI were examined in both groups.

Results: In-hospital mortalities were 0.7% (3/453) in the OAR group and 0.5% (1/189) in the EVAR group. The incidence of AKI increased in the OAR group (14.1% vs. 3.7%, P<0.01). In the OAR group, in-hospital mortality (0% vs. 4.7%, P<0.01) increased in patients with AKI. In the OAR group, hemoglobin level <10 g/dL, estimated glomerular filtration rate <60 mL/min/1.73 m², operation time >300 min, history of ischemic heart disease, and amount of bleeding >1,000 mL were predictors of AKI. In the EVAR group, amount of transfusion>1,000 mL was a predictor of AKI, but AKI was not found to worsen outcomes.

Conclusion: AKI affected outcomes of OAR. Knowledge of predictors may optimize perioperative care.

Epidemiology, outcomes, and management of acute kidney injury in the vascular surgery patient

OBJECTIVE

Conventional clinical wisdom has often been nihilistic regarding the prevention and management of acute kidney injury (AKI), despite its being a frequent and morbid complication associated with both increased mortality and cost. Recent developments have shown that AKI is not inevitable and that changes in management of patients can reduce both the incidence and morbidity of perioperative AKI. The purpose of this narrative review was to review the epidemiology and outcomes of AKI in patients undergoing vascular surgery using current consensus definitions, to discuss some of the novel emerging risk stratification and prevention techniques relevant to the vascular surgery patient, and to describe a standardized perioperative pathway for the prevention of AKI after vascular surgery.

METHODS

We performed a critical review of the literature on AKI in the vascular surgery patient using the PubMed and MEDLINE databases and Google Scholar through September 2017 using web-based search engines. We also searched the guidelines and publications available online from the organizations Kidney Disease: Improving Global Outcomes and the Acute Dialysis Quality Initiative. The search terms used included acute kidney injury, AKI, epidemiology, outcomes, prevention, therapy, and treatment.

RESULTS

The reported epidemiology and outcomes associated with AKI have been evolving since the publication of consensus criteria that allow accurate identification of mild and moderate AKI. The incidence of AKI after major vascular surgery using current criteria is as high as 49%, although there are significant differences, depending on the type of procedure performed. Many tools have become available to assess and to stratify the risk for AKI and to use that information to prevent AKI in the surgical patient. We describe a standardized clinical assessment and management pathway for vascular surgery patients, incorporating current risk assessment and preventive strategies to prevent AKI and to decrease its complications. Patients without any risk factors can be managed in a perioperative fast-track pathway. Those patients with positive risk factors are tested for kidney stress using the urinary biomarker TIMP-2•IGFBP7, and care is then stratified according to the result. Management follows current Kidney Disease: Improving Global Outcomes guidelines.

CONCLUSIONS

AKI is a common postoperative complication among vascular surgery patients and has a significant impact on morbidity, mortality, and cost. Preoperative risk assessment and optimal perioperative management guided by that risk assessment can minimize the consequences associated with postoperative AKI. Adherence to a standardized perioperative pathway designed to reduce risk of AKI after major vascular surgery offers a promising clinical approach to mitigate the incidence and severity of this challenging clinical problem.

Impact of aortic wall thrombus on late changes in renal function among patients treated by fenestrated-branched endografts

OBJECTIVE

Renal function deterioration is an important determinant of mortality in patients treated for complex aortic aneurysms. We have previously determined that catheter and guidewire manipulation in diseased aortas during fenestrated-branched endovascular aneurysm repair (F-BEVAR) is associated with risk of renal function deterioration. The aim of this study was to describe the impact of atherothrombotic aortic wall thrombus (AWT) on renal function deterioration among patients treated by F-BEVAR for pararenal and extent IV thoracoabdominal aortic aneurysms.

METHODS

Clinical data of 212 patients treated for complex aortic aneurysms with F-BEVAR were entered into a prospectively maintained database (2007-2015). AWT was evaluated by computed tomography angiography using volumetric measurements in nonaneurysmal aortic segments. AWT was classified as mild, moderate, or severe using objective assessment of the number of affected segments, thrombus type, thickness, area, and circumference. Acute kidney injury (AKI) was defined using Risk, Injury, Failure, Loss of kidney function, and End-stage renal disease (RIFLE) criteria, and renal function deterioration was defined by a decline in estimated glomerular filtration rate (eGFR) >30% from baseline. Patient survival and renal outcomes were assessed at dismissal, at 6 to 8 weeks, at 6 months, and annually, including AKI, serum creatinine concentration, eGFR, chronic kidney disease stage, need for renal replacement therapy, and presence of kidney infarction.

RESULTS

There were 169 male (80%) and 43 female (20%) patients with a mean age of 75 ± 7 years. Aneurysm extent was pararenal in 157 patients and extent IV thoracoabdominal aortic aneurysm in 55 patients. A total of 700 renal-mesenteric arteries were incorporated (3.1 ± 1 vessels/patient). AWT was classified as mild in 98 patients (46%), moderate in 75 (35%), and severe in 39 (19%). At 30 days, 45 patients (21%) developed AKI. Decline in eGFR and kidney infarction were associated with higher AWT volume index and severe AWT classification (P < .05). There was no association of AWT with 30-day mortality, which was 0.5% for the entire cohort. Mean follow-up was 29 ± 23 months. Freedom from renal function deterioration was 73% ± 6% for mild, 81% ± 6% for moderate, and 66% ± 8% for severe AWT patients at 3 years (P = .012) and 46% ± 9% and 82% ± 4% for those with or without AKI after the initial procedure (P < .001). Overall, 41 patients (19%) had progression of chronic kidney disease stage, but none of the patients required renal replacement therapy. Survival was 73% ± 5% for mild, 72% ± 6% for moderate, and 69% ± 10% for severe AWT patients at 3 years (P = .67).

CONCLUSIONS

AWT is a significant predictor of AKI and continued decline in renal function after the initial F-BEVAR procedure. Longer follow-up time is needed to determine the actual impact of AWT on survival.

Patients with end-stage renal disease have poor outcomes after endovascular abdominal aortic aneurysm repair

OBJECTIVE

Although endovascular repair of abdominal aortic aneurysms (AAAs) has been demonstrated to have favorable outcomes, not all cohorts of patients with AAA fare equally well. Our goal was to investigate perioperative and 1-year outcomes in patients with end-stage renal disease (ESRD) on dialysis, who have traditionally fared worse after vascular interventions, to assess how ESRD affects outcomes in a large modern cohort of endovascular aneurysm repair (EVAR) patients.

METHODS

The Vascular Quality Initiative database was queried for all patients undergoing EVAR from 2010 to 2017. ESRD patients were compared with patients not on dialysis. Propensity-matched scoring and multivariable analysis were used to isolate the effects of ESRD.

RESULTS

Of 28,683 EVARs identified, there were 321 (1.12%) patients with ESRD on dialysis. Patients with ESRD had no difference in presenting AAA size (57.5 ± 12.7 mm vs 56.7 ± 17.2 mm; P = .44); however, they had more urgent/emergent repairs (20.6% vs 13.6%; P = .002) than those without ESRD. ESRD patients were more often younger, nonwhite, and nonobese and less likely to have commercial insurance (P < .05). ESRD patients more often had hypertension, coronary artery disease, congestive heart failure, previous lower extremity bypass, aneurysm repair, and carotid interventions (P < .05). There was no difference in the rate of concomitant procedures. Matching based on demographics, comorbidities, and operative details showed that ESRD patients had longer hospital length of stay (4.8 ± 9.4 days vs 4.1 ± 12.6 days; P = .026) and higher 30-day mortality (7% vs 2.4%; P < .001). There was no difference in cardiac, pulmonary, lower extremity, bowel, and stroke complications or return to the operating room. On multivariable analysis, ESRD was associated with 30-day mortality (odds ratio, 4.1; 95% confidence interval, 2.6-6.7; P < .001). Of the 24,750 elective EVARs, 1.04% had ESRD on dialysis. Matched data for elective EVAR show increased postoperative length of stay, hospital mortality, and 30-day mortality for ESRD patients on dialysis compared with those who are not. There was no association with postoperative myocardial infarction or pulmonary complications. At 1 year, patients with ESRD on dialysis had worse survival (78% vs 94%; P < .001), and ESRD was associated with higher mortality (hazard ratio, 3.3; 95% confidence interval, 2.5-4.2; P < .001).

CONCLUSIONS

Among patients undergoing EVAR, ESRD is independently associated with higher perioperative and 1-year mortality despite not being associated with higher postoperative complications. This should be taken into account during informed consent for EVAR and risk-benefit considerations in this high-risk population, particularly for elective repair.

Feasibility of three-dimensional fusion imaging with multimodality roadmap system during endovascular aortic repair

OBJECTIVE

Endovascular procedures for aortic aneurysm repair have become widely accepted as safe and effective surgical options. We investigated the efficacy of the multimodality roadmap (MMR) system with biplane fluoroscopy to attempt to reduce the use of contrast medium and exposure to radiation during surgery.

METHODS

We retrospectively reviewed 263 consecutive cases with elective endovascular aneurysm repair (EVAR) and thoracic endovascular aortic repair (TEVAR). Patients were categorized into two groups, with and without introduction of the MMR system, which was applied in 164 patients (62.4%). The MMR- group included 62 EVAR and 37 TEVAR cases, and the MMR+ group consisted of 81 EVAR and 83 TEVAR cases. Radiation dose, contrast medium use, and complications were compared between the MMR- and MMR+ groups in the respective EVAR and TEVAR groups.

RESULTS

There was a significantly lower amount of contrast medium use in the MMR+ group compared with the MMR- group in EVAR (32.9 ± 10.6 g and 28.2 ± 10.2 g; P = .009) and TEVAR (31.7 ± 11.5 g and 26.9 ± 7.8 g; P = .009). In addition, significantly lower radiation exposure was observed in the MMR+ group of TEVAR (872 ± 623 mGy vs 638 ± 463 mGy; P = .033). The operative time of the MMR+ group was significantly shorter for patients with TEVAR compared with the MMR- group (96.4 ± 27.0 minutes vs 86.2 ± 23.9 minutes; P = .023). The incidence of access injury and other complications was similar in both EVAR and TEVAR groups.

CONCLUSIONS

The MMR system with three-dimensional fusion imaging can reduce the contrast medium dose in EVAR and the exposure to contrast medium and radiation in TEVAR.

Partial renal coverage in endovascular aneurysm repair causes unfavorable renal flow patterns in an infrarenal aneurysm model

OBJECTIVE

To achieve an optimal sealing zone during endovascular aneurysm repair, the intended positioning of the proximal end of the endograft fabric should be as close as possible to the most caudal edge of the renal arteries. Some endografts exhibit a small offset between the radiopaque markers and the proximal fabric edge. Unintended partial renal artery coverage may thus occur. This study investigated the consequences of partial coverage on renal flow patterns and wall shear stress (WSS).

METHODS

In vitro models of an abdominal aortic aneurysm were used to visualize pulsatile flow using two-dimensional particle image velocimetry under physiologic resting conditions. One model served as control and two models were stented with an Endurant endograft (Medtronic Inc, Minneapolis, Minn), one without and one with partial renal artery coverage with 1.3 mm of stent fabric extending beyond the marker (16% area coverage). The magnitude and oscillation of WSS, relative residence time, and backflow in the renal artery were analyzed.

RESULTS

In both stented models, a region along the caudal renal artery wall presented with low and oscillating WSS, not present in the control model. A region with very low WSS (<0.1 Pa) was present in the model with partial coverage over a length of 7 mm compared with a length of 2 mm in the model without renal coverage. Average renal backflow area percentage in the renal artery incrementally increased from control (0.9%) to the stented model without (6.4%) and with renal coverage (18.8%).

CONCLUSIONS

In this flow model, partial renal coverage after endovascular aneurysm repair causes low and marked oscillations in WSS, potentially promoting atherosclerosis and subsequent renal artery stenosis. Awareness of the device-dependent offset between the fabric edge and the radiopaque markers is therefore important in endovascular practice.

Use of Synchrotron Radiation to Accurately Assess Cross-Sectional Area Reduction of the Aortic Branch Ostia Caused by Suprarenal Stent Wires

PURPOSE

To compare in vivo the use of synchrotron radiation to computed tomography angiography (CTA) for the measurement of cross-sectional area (CSA) reduction of the aortic branch ostia caused by suprarenal stent-graft wires.

METHODS

This study was performed with a Zenith stent-graft placed in a phantom of the human aorta to simulate treatment of abdominal aortic aneurysm. Synchrotron radiation scans were performed using beam energies between 40 and 100 keV and spatial resolution of 19.88 μm per pixel. CSA reduction of the aortic branch ostia by suprarenal stent wires was calculated based on these exposure factors and compared with measurements from CTA images acquired on a 64-row scanner with slice thicknesses of 1.0, 1.5, and 2.0 mm.

RESULTS

Images acquired with synchrotron radiation showed <10% of the CSA occupied by stent wires when a single wire crossed a renal artery ostium and <20% for 2 wires crossing a renovisceral branch ostium. The corresponding areas ranged from 24% to 25% for a single wire and from 40% to 48% for double wires crossing the branch ostia when measured on CT images. The stent wire was accurately assessed on synchrotron radiation with a diameter between 0.38±0.01 and 0.53±0.03 mm, which is close to the actual size of 0.47±0.01 mm. The wire diameter measured on CT images was greatly overestimated (1.15±0.01 to 1.57±0.02 mm).

CONCLUSION

CTA has inferior spatial resolution that hinders accurate assessment of CSA reduction. This experiment demonstrated the superiority of synchrotron radiation over CTA for more accurate assessment of aortic stent wires and CSA reduction of the aortic branch ostia.

Open and endovascular aneurysm repair in the Society for Vascular Surgery Vascular Quality Initiative

The Society for Vascular Surgery Vascular Quality Initiative is a patient safety organization and a collection of procedure-based registries that can be utilized for quality improvement initiatives and clinical outcomes research. The Vascular Quality Initiative consists of voluntary participation by centers to collect data prospectively on all consecutive cases within specific registries which physicians and centers elect to participate. The data capture extends from preoperative demographics and risk factors (including indications for operation), through the perioperative period, to outcomes data at up to 1-year of follow-up. Additionally, longer-term follow-up can be achieved by matching with Medicare claims data, providing long-term longitudinal follow-up for a majority of patients within the Vascular Quality Initiative registries. We present the unique characteristics of the Vascular Quality Initiative registries and highlight important insights gained specific to open and endovascular abdominal aortic aneurysm repair.