Impact of Endovascular Aortic Aneurysm Repair in a Renal Transplantation Program

The immediate post-operative impact of infrarenal aortic endografts on renal arterial flow dynamics: Insights from four-dimensional flow magnetic resonance imaging analysis

OBJECTIVES

This study aims to quantify changes in renal blood flow before and after endovascular aneurysm repair (EVAR) using four-dimensional (4D) flow magnetic resonance imaging (MRI) and evaluate its correlation with renal impairment.

METHODS

In this retrospective analysis, 18 patients underwent elective EVAR for infrarenal fusiform abdominal aortic aneurysms using Excluder or Endurant endografts. 4D flow MRI scans were conducted before and 1-4 days after EVAR. Hemodynamics were quantified at the suprarenal aorta (SupAo), bilateral renal arteries (RRA and LRA), and infrarenal aorta (InfAo). Cardiac phase-resolved blood flow values (BFVs), relative flow distribution (RFD), and flow change rates (FCRs) were assessed. Estimated glomerular filtration rate (eGFR) was measured pre- and postoperatively.

RESULTS

A total of 16 patients were analyzed after excluding two outliers. Pre-EVAR BFVs were 23.1 ± 8.3, 3.7 ± 1.3, 3.4 ± 1.2, and 15.1 ± 5.9 mL/cycle, while post-EVAR BFVs were 20.9 ± 6.9, 3.8 ± 1.1, 3.2 ± 0.9, and 12.1 ± 4.3 mL/cycle in SupAo, RRA, LRA, and InfAo, respectively. Comparing Excluder (N = 8) and Endurant (N = 8), the total renal FCR was 121.8% [106.6-144.7] versus 101.3% [63.8-121.8] (p = 0.110), suggesting a potential improvement in renal blood flow with the Excluder, although not statistically significant. A significant correlation was found between the total renal FCR and the relative eGFR at 6 months (Spearman correlation coefficient, 0.789; p < 0.001).

CONCLUSIONS

The endografts, particularly the Excluder, showed potential in improving renal artery blood flow in some patients. The significant correlation between the total renal FCR and the relative eGFR at 6 months suggests that acute hemodynamic alterations induced by EVAR may impact post-operative renal function. Further research is needed to confirm these findings and assess their clinical implications.

Renal transplant recipients undergoing endovascular abdominal aortic aneurysm repair have increased risk of perioperative acute kidney injury but no difference in late mortality

OBJECTIVE

Renal transplant is associated with substantial survival advantage in patients with end-stage renal disease. However, little is known about the outcomes of renal transplant recipients (RTRs) after endovascular abdominal aortic aneurysm repair (EVAR). This study aimed to study the effect of renal transplant on perioperative outcomes and long-term survival after elective infrarenal EVAR.

METHODS

The Vascular Quality Initiative database was queried for all patients undergoing elective EVAR from 2003 to 2021. Functioning RTRs were compared with non-renal transplant recipients without a diagnosis of end-stage renal disease (non-RTRs). The outcomes included 30-day mortality, acute kidney injury (AKI), new renal failure requiring renal replacement therapy (RRT), endoleak, aortic-related reintervention, major adverse cardiac events, and 5-year survival. A logistic regression analysis was used to assess the association between RTRs and perioperative outcomes.

RESULTS

Of 60,522 patients undergoing elective EVAR, 180 (0.3%) were RTRs. RTRs were younger (median, 71 years vs 74.5 years; P < .001), with higher incidence of hypertension (92% vs 84%; P = .004) and diabetes (29% vs 21%; P = .005). RTRs had higher median preoperative serum creatinine (1.3 mg/dL vs 1.0 mg/dL; P < .001) and lower estimated glomerular filtration rate (51.6 mL/min vs 69.4 mL/min; P < .001). There was no difference in the abdominal aortic aneurysm diameter and incidence of concurrent iliac aneurysms. Procedurally, RTRs were more likely to undergo general anesthesia with lower amount of contrast used (median, 68.6 mL vs 94.8 ml; P < .001) and higher crystalloid infusion (median, 1700 mL vs 1500 mL; P = .039), but no difference was observed in the incidence of open conversion, endoleak, operative time, and blood loss. Postoperatively, RTRs experienced a higher rate of AKI (9.4% vs 2.7%; P < .001), but the need for new RRT was similar (1.1% vs 0.4%; P = .15). There was no difference in the rates of postoperative mortality, aortic-related reintervention, and major adverse cardiac events. After adjustment for potential confounders, RTRs remained associated with increased odds of postoperative AKI (odds ratio, 3.33; 95% confidence interval, 1.93-5.76; P < .001) but had no association with other postoperative complications. A subgroup analysis identified that diabetes (odds ratio, 4.21; 95% confidence interval, 1.17-15.14; P = .02) is associated with increased odds of postoperative AKI among RTRs. At 5 years, the overall survival rates were similar (83.4% vs 80%; log-rank P = .235).

CONCLUSIONS

Among patients undergoing elective infrarenal EVAR, RTRs were independently associated with increased odds of postoperative AKI, without increased postoperative renal failure requiring RRT, mortality, endoleak, aortic-related reintervention, or major adverse cardiac events. Furthermore, 5-year survival was similar. As such, while EVAR may confer comparable benefits and technical success perioperatively, RTRs should have aggressive and maximally optimized renal protection to mitigate the risk of postoperative AKI.

Axillary-iliac bypass to protect a transplanted kidney during abdominal aortic aneurysm repair: case report

Abdominal aortic aneurysms (AAA) are the most common type, even when compared to those involving other segments of the aorta. The prevalence and natural history of arterial aneurysms in abdominal organ transplant recipients remain uncertain. We report a case of abdominal aortic aneurysm in a kidney transplant patient with contrast allergy. Conventional abdominal aortic aneurysm repair was performed, constructing a bi-iliac aortic bypass. A temporary bypass was constructed from the right axillary artery to the right common iliac artery to maintain the renal graft. The patient was transferred to the intensive care unit, where he remained hemodynamically stable, and he was discharged on the 2nd postoperative day. Conventional open surgery with temporary extra-anatomic bypass is an alternative option for treatment of AAA in patients with transplanted kidneys.

Renal Transplant Patients Undergo Abdominal Aortic Aneurysm Repair at a Younger Age and Experience More Complications: Review of the Healthcare Cost and Utilization Project Database

OBJECTIVE

The objective of this study was to determine whether history of kidney transplant is a risk factor for increased complications in patients who undergo abdominal aortic aneurysm (AAA) repair.

BACKGROUND

The incidence of renal failure and subsequent kidney transplant is steadily rising. Many risk factors leading to AAA overlap with those of renal disease. Due to these similarities, a rising incidence of kidney transplant patients undergoing AAA repair is expected. We surmised a notable difference in AAA surgical repair outcomes in renal transplant recipients compared to the general population.

METHODS

A retrospective analysis was performed on 59,836 adult patients with history of AAA repair and kidney transplant from 2008 to 2015. Data were obtained from the Nationwide Inpatient Sample database developed for the Healthcare Cost and Utilization Project.

RESULTS

Significant differences in age, race, hospital characteristics, and complications were identified. The results suggest that patients with prior transplant generally have AAA repair at a significantly younger age (P < .001). A difference in race (P = .017), with 75% vs 87.4% non-Hispanic whites and 5% vs 1.5% Asian/Pacific Islander in the transplant and nontransplant groups, respectively, was shown. Procedures at transplant centers had significantly longer lengths of stay (P < .001) and higher total charges (P < .001). In addition, transplant recipients exhibited a higher in-hospital mortality index (P < .001) than the nontransplanted population.

CONCLUSION

A history of kidney transplant significantly influences multiple aspects of care and complications regarding future AAA repair and is associated with increased in-hospital mortality index. Significant findings include increased total charges, longer lengths of stay, postoperative complications, and differences in age and race.