Learning Curve Analysis of Complex Endovascular Aortic Repair

BACKGROUND

When introducing new techniques, attention must be paid to learning curve. Besides quantitative outcomes, qualitative factors of influence should be taken into consideration. This retrospective cohort study describes the quantitative learning curve of complex endovascular aortic repair (EVAR) in a nonhigh-volume academic center and provides qualitative factors that were perceived as contributors to this learning curve. With these factors, we aim to aid in future implementation of new techniques.

METHODS

All patients undergoing complex EVAR in the Leiden University Medical Center (LUMC) between July 2013 and April 2021 were included (n = 90). Quantitative outcomes were as follows: operating time, blood loss, volume of contrast, hospital stay, major adverse events (MAE), 30-day mortality, and complexity. Patients were divided into 3 temporal groups (n = 30) for dichotomous outcomes. Regression plots were used for continuous outcomes. In 2017, the treatment team was interviewed by an external researcher. These interviews were reanalyzed for factors that contributed to successful implementation.

RESULTS

Length of hospital stay (P = 0.008) and operating time (P = 0.010) decreased significantly over time. Fewer cardiac complications occurred in the third group (3: 0% vs. 2: 17% vs. 1: 17%, P = 0.042). There was a trend of increasing complexity (P = 0.076) and number of fenestrations (P = 0.060). No significant changes occurred in MAE and 30-day mortality. Qualitative factors that, according to the interviewees, positively influenced the learning curve were as follows: communication, mutual trust, a shared sense of responsibility and collective goals, clear authoritative structures, mutual learning, and team capabilities.

CONCLUSIONS

In addition to factors previously identified in the literature, new learning curve factors were found (mutual learning and shared goals in the operating room (OR)) that should be taken into account when implementing new techniques.

Systematic review with pooled data analysis reveals the need for a standardized reporting protocol including the visceral vessels during fenestrated endovascular aortic repair (FEVAR)

OBJECTIVES

To collect and analyse the available evidence in the outcomes of patients treated with fenestrated endovascular aortic repair (f-EVAR) technique focusing specifically on visceral vessel outcomes.

METHODS

The current meta-analysis was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All the studies reporting the f-EVAR technique for the management of degenerative pararenal and/or type IV thoracoabdominal aortic aneurysms (TAAA) were considered eligible for inclusion in the study. The main study outcomes (technical success, type I endoleaks, fracture or occlusion of the bridging stents, overall aneurysm-related mortality, and the reintervention rate) were subsequently expressed as proportions and 95% confidence intervals.

RESULTS

Fourteen studies with a total of 1804 patients were included in a pooled analysis. The technical success of the procedure was 95.97% (95%CI = 92.35-98.60). Intraoperatively, the pooled proportion of reported type I endoleak was 7.6% (95%CI = 2.52-14.60) while during a median follow-up of 41 months (range 11-96) follow-up period the pooled rate of fracture and occlusion of the bridging stents was 2.79% (95%CI = 0.00-8.52) and 4.46% (95%CI = 1.93-7.77), respectively. The overall aneurysm-related mortality was detected to be 0.63% (95%CI = 0.04-1.63), and the pooled estimate for re-intervention rate was 15.69%.

CONCLUSIONS

Fenestrated endovascular repair for p-AAA is an effective and safe treatment. Target vessel complications and endoleaks remain the two most important concerns for fenestrated endovascular procedures, contributing to most of the secondary interventions. The lack of computed tomography angiography follow-up evaluation does not allow us to draw robust conclusions about the complication rates for the superior mesenteric artery during f-EVAR. Due to the potential implications of SMA complications on aneurysm-related mortality, standardized reporting of short- and long-term target visceral vessel outcomes is required.

The Effect of Hypogastric Artery Revascularization on Ischemic Colitis in Endovascular Aneurysm Repair

BACKGROUND

The objective of the study was to examine the effect of hypogastric revascularization maneuvers on the rate of postoperative ischemic colitis among patients undergoing endovascular aortoiliac aneurysm repair.

METHODS

Using the 2011-2018 Endovascular Aneurysm Repair Procedure-Targeted American College of Surgeons National Surgical Quality Improvement Program Participant Use Files, we analyzed patients undergoing elective endovascular infrarenal aortoiliac aneurysm repairs. Using multivariable modeling techniques, a cohort of patients at high risk for postoperative ischemic colitis was identified. The outcomes of this group were then compared using Pearson's chi-square testing in accordance with whether or not they underwent hypogastric revascularization.

RESULTS

Of 4753 patients undergoing endovascular aortoiliac aneurysm repair in the National Surgical Quality Improvement Program cohort, 1161 had concomitant hypogastric revascularization procedures. High-risk predictors of ischemic colitis included chronic obstructive pulmonary disease and concurrent renal artery or external iliac artery stenting. There was not a significant association between pelvic revascularization and postoperative ischemic colitis [1.0% with versus 0.5% without pelvic revascularization; adjusted odds ratio of ischemic colitis with revascularization 2.07 (0.96, 4.46); P = 0.06] after adjustment for patient- and procedure-related factors. In a subgroup analysis of patients with a distal aneurysm extent beyond the common iliac artery, the incidence of ischemic colitis was significantly lower in patients without pelvic revascularization (0.1% versus 1.6%, P = 0.004).

CONCLUSIONS

Our analysis of patients undergoing elective endovascular repair of infrarenal aortoiliac aneurysmal disease did not find a reduced incidence of postoperative ischemic colitis in patients who received a concomitant pelvic revascularization procedure, suggesting instead that such procedural adjuncts may actually increase risk for this complication.

Increasing Role of Fenestrated and Branched Endoluminal Techniques in the Thoracoabdominal Segment Including Supra- and Pararenal AAA

Fenestrated and branched stent-grafts are being increasingly used to address complex pararenal and thoracoabdominal aortic aneurysms by endovascular means. The present paper describes the current indications, anatomical suitability and techniques of fenestrated and branched stent-grafts in the treatment for pararenal and thoracoabdominal aortic pathologies. Published outcomes with regard to perioperative mortality and morbidity, survival, reinterventions and target vessel patency during follow-up are also presented. Finally, advantages and disadvantages of endovascular repair as compared to open repair are discussed.

Endovascular Abdominal Aortic Aneurysm Repair

Most abdominal aortic aneurysms are treated with endovascular repair (EVAR) in current practice. EVAR has lower periprocedural mortality and morbidity than open surgical repair. Aneurysm neck morphology, iliac anatomy, and access vessel anatomy need careful assessment for the successful performance of EVAR. Regular and long-term follow-up with imaging is mandatory after EVAR, and patients who are less likely to comply are less favorable EVAR candidates. Endoleaks are the most frequent complication of EVAR. Most can be managed with transcatheter or endovascular means. Evolving technology and techniques are allowing more patients to be treated with EVAR with better long-term outcomes.

Navigation and visualisation with HoloLens in endovascular aortic repair

Introduction

Endovascular aortic repair (EVAR) is a minimal-invasive technique that prevents life-threatening rupture in patients with aortic pathologies by implantation of an endoluminal stent graft. During the endovascular procedure, device navigation is currently performed by fluoroscopy in combination with digital subtraction angiography. This study presents the current iterative process of biomedical engineering within the disruptive interdisciplinary project Nav EVAR, which includes advanced navigation, image techniques and augmented reality with the aim of reducing side effects (namely radiation exposure and contrast agent administration) and optimising visualisation during EVAR procedures. This article describes the current prototype developed in this project and the experiments conducted to evaluate it.

Methods

The current approach of the Nav EVAR project is guiding EVAR interventions in real-time with an electromagnetic tracking system after attaching a sensor on the catheter tip and displaying this information on Microsoft HoloLens glasses. This augmented reality technology enables the visualisation of virtual objects superimposed on the real environment. These virtual objects include three-dimensional (3D) objects (namely 3D models of the skin and vascular structures) and two-dimensional (2D) objects [namely orthogonal views of computed tomography (CT) angiograms, 2D images of 3D vascular models, and 2D images of a new virtual angioscopy whose appearance of the vessel wall follows that shown in ex vivo and in vivo angioscopies]. Specific external markers were designed to be used as landmarks in the registration process to map the tracking data and radiological data into a common space. In addition, the use of real-time 3D ultrasound (US) is also under evaluation in the Nav EVAR project for guiding endovascular tools and updating navigation with intraoperative imaging. US volumes are streamed from the US system to HoloLens and visualised at a certain distance from the probe by tracking augmented reality markers. A human model torso that includes a 3D printed patient-specific aortic model was built to provide a realistic test environment for evaluation of technical components in the Nav EVAR project. The solutions presented in this study were tested by using an US training model and the aortic-aneurysm phantom.

Results

During the navigation of the catheter tip in the US training model, the 3D models of the phantom surface and vessels were visualised on HoloLens. In addition, a virtual angioscopy was also built from a CT scan of the aortic-aneurysm phantom. The external markers designed for this study were visible in the CT scan and the electromagnetically tracked pointer fitted in each marker hole. US volumes of the US training model were sent from the US system to HoloLens in order to display them, showing a latency of 259±86 ms (mean±standard deviation).

Conclusion

The Nav EVAR project tackles the problem of radiation exposure and contrast agent administration during EVAR interventions by using a multidisciplinary approach to guide the endovascular tools. Its current state presents several limitations such as the rigid alignment between preoperative data and the simulated patient. Nevertheless, the techniques shown in this study in combination with fibre Bragg gratings and optical coherence tomography are a promising approach to overcome the problems of EVAR interventions.

Editor's Choice - Comparison of Renal Outcomes in Patients Treated by Zenith® Fenestrated and Zenith® Abdominal Aortic Aneurysm Stent grafts in US Prospective Pivotal Trials

OBJECTIVE/BACKGROUND

Fenestrated endovascular repair (FEVAR) has been used to treat complex abdominal aortic aneurysms (AAAs). The risk of renal function deterioration compared with infrarenal endovascular aortic repair (EVAR) has not been determined.

METHODS

Patients with preserved renal function (estimated glomerular filtration rate [eGFR] > 45 mL/minute) enrolled in two prospective, non-randomised studies evaluating Zenith fenestrated and AAA stent grafts were matched (1:2) by propensity scores for age, sex, hypertension, diabetes, and pre-operative eGFR. Sixty-seven patients were treated by FEVAR and 134 matched controls treated by EVAR. Mean follow-up was 30 ± 20 months. Outcomes included acute kidney injury (AKI) defined by RIFLE and changes in serum creatinine (sCr), eGFR, and chronic kidney disease (CKD) staging up to 5 years.

RESULTS

AKI at 1 month was similar between groups, with > 25% decline in eGFR observed in 5% of FEVAR and 9% of EVAR patients (p = .39). There were no significant differences in > 25% decline in eGFR at 2 years (FEVAR 20% vs. EVAR 20%; p > .99) or 5 years (FEVAR 27% vs. EVAR 50%; p = .50). Progression to stage IV-V CKD was similar at 2 years (FEVAR 2% vs. EVAR 3%; p > .99) and 5 years (FEVAR 7% vs. EVAR 8%; p > .99), with similar sCr and eGFR up to 5 years. During follow-up, there were more renal artery stenosis/occlusions (15/67 [22%] vs. 3/134 [2%]; p < .001) and renal related re-interventions (12/67 [18%] vs. 4/134 [3%]; p < .001) in patients treated by FEVAR. Rate of progression to renal failure requiring dialysis was low and identical in both groups (1.5% vs. 1.5%; p > .99).

CONCLUSION

Aortic repair with FEVAR and EVAR was associated with similar rates of renal function deterioration in patients with preserved pre-operative renal function. Renal related re-interventions were higher following FEVAR, although net changes in renal function were similar in both groups.

Treatment of complex aortic aneurysms with fenestrated endografts and chimney stent repair: Systematic review and meta-analysis

Objective

We reviewed data pertaining to fenestrated endograft technique and chimney stent repair of complex aortic aneurysm for comparative analysis of the outcomes.

Methods

A comprehensive search of relevant databases was conducted to identify articles in English, related to the treatment of complex aortic aneurysm with fenestrated endovascular aneurysm repair and chimney stent repair, published until January 2015.

Results

A total of 42 relevant studies and 2264 patients with aortic aneurysm undergoing fenestrated endovascular aneurysm repair and chimney stent repair were included in our review. A total of 4413 vessels were involved in these processes. The cumulative 30-day mortality was 2.4% and 3.2% ( p = 0.459). The follow-up aneurysm-related mortality was 1.4% and 3.2% ( p = 0.018), and target organ dysfunction was 5.0% and 4.0% in fenestrated endovascular aneurysm repair and chimney stent repair, respectively ( p = 0.27). A total of 156 vessels showed restenosis or occlusion after primary intervention (3.6% and 3.4% in fenestrated endovascular aneurysm repair and chimney stent repair, respectively, p = 0.792). The cumulative type I endoleak was 2.0% (38/1884) after fenestrated endovascular aneurysm repair compared with 3.4% (13/380) after chimney stent repair ( p = 0.092), and the type II endoleak was 5.4% (102/1884) and 5.3% (20/380), respectively ( p = 0.905). Approximately, 1.1% and 1.6% increase in aneurysm was observed following fenestrated endovascular aneurysm repair and chimney stent repair, respectively ( p = 0.437). The re-intervention frequency was 205 and 19 cases after fenestrated endovascular aneurysm repair and chimney stent repair, respectively (11.7%, 5.6%, p = 0.001).

Conclusions

Fenestrated endovascular aneurysm repair and chimney stent repair are safe and effective in treating patients with complex aortic aneurysm. A higher aneurysm-related mortality was observed in chimney stent repair while fenestrated endovascular aneurysm repair was associated with a higher re-intervention rate.

Fenestrated stent grafts for the treatment of complex aortic aneurysm disease: A mature treatment paradigm

The introduction of fenestrated stent grafts (SGs) to treat abdominal aortic aneurysms (AAAs) with short proximal necks began in 1999. Nowadays, the whole visceral aorta can be treated totally by endovascular means. The established use of fenestrated devices to treat complex AAAs as a first-line management option has been previously reported. An up-to-date evaluation of the literature was performed including all types of publications regarding the use of fenestrated technology to repair complex AAAs. Fenestrated repair is now an established alternative to hybrid/chimney/snorkel repairs. However, specific criteria and prerequisites are required for the use and improvement of this method. Multiple device morphologies have been used incorporating the visceral arteries in various combinations. This modular strategy connects different devices (bridging covered stents and bifurcated SGs) with the aortic main body, thus excluding the aneurysm from the circulation. Precise deployment of the fenestrated SG is mandatory for successful visceral vessel revascularization. Accurate SG sizing and customization, a high level of technical skill, and facilities with modern imaging techniques including 3D road mapping and dedicated hybrid rooms are required. Most experience has been with the custom-made Zenith Cook platform, although off-the-shelf devices have been recently implanted. More complex repairs have been performed over the last few years, but device complexity has also increased. Perioperative, mid-term, and a few recently reported long-term results are encouraging. Secondary interventions remain the main problem, similar to that observed after traditional endovascular abdominal aortic aneurysm repair (EVAR).

Editor's choice - thirty day outcomes and costs of fenestrated and branched stent grafts versus open repair for complex aortic aneurysms

OBJECTIVE

To compare 30 day outcomes and costs of fenestrated and branched stent grafts (f/b EVAR) and open surgery (OSR) for the treatment of complex abdominal aortic aneurysms (AAA) and thoraco-abdominal aortic aneurysms (TAAA).

METHODS

The multicenter prospective registry WINDOW was set up to evaluate f/b EVAR in high risk patients with para/juxtarenal AAA, and infradiaphragmatic and supradiaphragmatic TAAA. A control group of patients treated by OSR was extracted from the national hospital discharge database. The primary endpoint was 30 day mortality. Secondary endpoints included severe complications, length of stay, and costs. Mortality was assessed by survival analysis and uni/multivariate Cox regression analyses using pre- and post-operative characteristics. Bootstrap methods were used to estimate the cost-effectiveness of f/b EVAR versus OSR.

RESULTS

Two hundred and sixty eight cases and 1,678 controls were included. There was no difference in 30 day mortality (6.7% vs. 5.4%, p = 0.40), but costs were higher with f/b EVAR (€38,212 vs. €16,497, p < .001). After group stratification, mortality was similar with both treatments for para/juxtarenal AAA (4.3% vs. 5.8%, p = .26) and supradiaphragmatic TAAA (11.9% vs. 19.7%, p = .70), and higher with f/b EVAR for infradiaphragmatic TAAA (11.9% vs. 4.0%, p = .010). Costs were higher with f/b EVAR for para/juxtarenal AAA (€34,425 vs. €14,907, p < .0001) and infradiaphragmatic TAAA (€37,927 vs. €17,530, p < .0001), but not different for supradiaphragmatic TAAA (€54,710 vs. €44,163, p = .18).

CONCLUSION

f/b EVAR does not appear justified for patients with para/juxtarenal AAA and infradiaphragmatic TAAA fit for OSR but may be an attractive option for patients with para/juxtarenal AAA not eligible for surgery and patients with supradiaphragmatic TAAA.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov/ct2/show/NCT01168037; identifier: NCT01168037 (WINDOW registry).

Fenestrated endovascular aneurysm repair

Background

Fenestrated endovascular aneurysm repair (FEVAR) is a technically challenging operation. The duration, blood loss, and risk of limb ischaemia, contrast-induced nephropathy and reperfusion injury are likely to be higher than after standard endovascular aneurysm repair (EVAR). Benefits of FEVAR over open repair may be less than those seen with standard infrarenal EVAR. This paper is a meta-analysis of observational studies of all published data for FEVAR, with the aim to highlight current issues around the evidence for the potential benefit of FEVAR.

Methods

A search was performed for studies describing FEVAR for juxtarenal abdominal aortic aneurysms. Small series of fewer than ten procedures and studies describing predominantly branched endografts or FEVAR for aortic dissection were excluded. Authors of included papers were contacted to eliminate patient duplication.

Results

Eleven studies were identified describing a total of 660 procedures. Definitions of aneurysm morphology were variable, and clear inclusion and exclusion criteria were not always documented. Double fenestrations were more common than triple or quadruple fenestrations. Target vessel perfusion rates ranged from 90·5 to 100 per cent. Eleven deaths occurred within 30 days, giving a 30-day proportional mortality rate of 2·0 per cent. Morbidity was poorly reported.

Conclusion

FEVAR for repair of suprarenal and juxtarenal aneurysms is a viable alternative to open repair. However, there is no level 1 evidence for FEVAR, and current evidence is weak with many unanswered questions.

EVAR and complex anatomy: an update on fenestrated and branched stent grafts

Endovascular aneurysm repair (EVAR) offers a minimally invasive treatment to patients with improved short-term and similar mid-term results compared to conventional, open repair (OR). EVAR is preferred by patients due to the reduction of surgical trauma. Approximately 20% of patients have aneurysm neck morphology which is inadequate for a standard stent graft and requires the endograft to cross vital aortic side branches to achieve a seal. This chapter describes the evolution of three types of devices, namely the fenestrated and branched stent grafts as well as the chimney grafts. These stent grafts incorporate vital aortic side branches in the repair, thereby increasing the applicability of EVAR which may improve the overall results.