Influence of Age, Aneurysm Size, and Patient Fitness on Suitability for Endovascular Aortic Aneurysm Repair

doi:10.1016/j.avsg.2008.08.034

Annals of Vascular Surgery

Volume 22, Issue 6, November 2008, Pages 730-735

https://doi.org/10.1016/j.avsg.2008.08.034 Get rights and content

Prior to approval by the U.S. Food and Drug Administration of larger endografts (main body diameters up to 36 mm), small abdominal aortic aneurysms (AAAs, <5.5 cm) were shown to be more suitable for endovascular repair (EVAR) than large AAAs (≥5.5 cm). The purpose of this study was to assess changes in EVAR suitability with the potential use of larger endografts in unselected consecutive patients. The influence of age, aneurysm size, and patient fitness on EVAR suitability was also assessed. We studied 186 male patients referred for evaluation of nonruptured AAAs who underwent contrast-enhanced computed tomographic scans with three-dimensional reconstructions. Morphologicall AAA features and neck characteristics were measured according to Society for Vascular Surgery reporting standards to determine EVAR suitability. Patient fitness for repair was assessed using the customized probability index, a validated fitness score for vascular surgery procedures. Suitability for EVAR was determined by neck anatomy, iliac artery morphology, and total aortic aneurysm angulation and tortuosity according to the clinicians' experience and current practice. The median age of the study cohort was 72 years (interquartile range [IQR] 65-79 years). The median maximum AAA diameter was 5.4 cm (IQR 4.1-5.9). Median fitness score was +7 (IQR -7 to +14). EVAR suitability for large AAAs significantly increased with larger endografts (35-63%, p < 0.001). Changes in EVAR suitability for small AAAs were not significant (69-75%, p = 0.06). Maximum AAA diameter was not an independent predictor for EVAR suitability with larger endografts after adjusting for neck anatomy. Aortic neck length (odds ratio [OR] = 1.2, 95% confidence interval [CI] 1.1-1.2) and diameter (OR = 0.78, 95% CI 0.63-0.96) were the only independent predictors for EVAR suitability with larger endografts. Age, AAA size, and fitness did not differ between patients suitable and unsuitable for EVAR with larger endografts. In conclusion, introduction of larger endografts (up to 36 mm in main body diameter) in the United States has resulted in significantly increased anatomic suitability for EVAR for large AAAs. Conversely, suitability has not significantly changed for small AAAs. Overall, EVAR suitability is not influenced by age, aneurysm size, or patient fitness.

Introduction

Age, abdominal aortic aneurysm (AAA) size, and gender have not been found to influence endovascular aneurysm repair (EVAR) suitability in observational studies.1, 2 Conversely, in a previous study from our institution in which the manufacturers' instructions for use were strictly followed to determine EVAR suitability, 64% of patients with small AAAs were candidates for EVAR compared with 39% of patients with large AAAs.³ Small AAAs had less complex anatomy with longer aortic necks, less neck angulation, and less tortuosity. Other morphological studies have also demonstrated that AAA maximum diameter is inversely related to the length of the aortic neck.⁴ Moreover, the diameter of the aneurysm has been shown to be the most useful surrogate determinant of feasibility for EVAR.4, 5 In a subsequent study, however, we demonstrated that morphological changes associated with aneurysm growth during surveillance of small AAAs were not clinically significant and had minimal effect on overall suitability for EVAR.⁶ In fact, EVAR suitability did not significantly change during mid-term follow-up (74% vs. 69%), suggesting that suitability is not affected by AAA size up to the threshold for repair.

In October 2004, the U.S. Food and Drug Administration approved the use of larger endografts (main body diameters up to 36 mm) for EVAR. Although few European studies have assessed EVAR suitability with the use of these larger endografts,2, 7 most American studies have used selection criteria for EVAR using endografts with main body diameters up to 28 or 32 mm.3, 8

Patient fitness has been identified as a major determinant of the need and outcome of AAA repair, including EVAR.9, 10 A customized probability index (CPI) based on comorbidities and the use of statins and beta-blockers has been proven to be a valid predictor for perioperative morbidity and mortality after vascular surgery procedures, including EVAR.9, 11 To date and to our knowledge, patient fitness and its association with EVAR suitability have not been assessed.

The purpose of this study was to determine changes in EVAR suitability with the potential use of larger endografts in consecutive unselective patients. The influence of age, aneurysm size, and patient fitness on EVAR suitability was also assessed.

Section snippets

Methods

During a 3-year period, 186 consecutive patients referred for AAA evaluation underwent helical computed tomographic (CT) scans at the Dallas Veterans Affairs Medical Center. All CT scans were performed using the helical Hi Speed I from GE Medical Systems (Milwaukee, WI) with collimation set at 3 mm and a 2.0 pitch. All CT scans were evaluated using three-dimensional reconstruction on a Vitrea workstation (Vital Images, Plymouth, MN). Morphological AAA characteristics were determined from each CT

Results

The median age of the study population was 72 years (IQR 65-79). All patients were male. The median maximum AAA diameter was 5.4 cm (IQR 4.1-5.9). Median fitness (CPI) score was +7 (IQR -7 to +14). Among 186 patients undergoing CT angiography, 136 (73%) had AAAs suitable for EVAR, whereas 50 (27%) were noncandidates for EVAR. One hundred twenty-nine patients (69%) had small AAAs (maximum diameter <5.5 cm), whereas 57 (31%) had large AAAs (≥5.5 cm in maximum diameter). Median ages of patients

Discussion

The results of our study indicate that the introduction of larger endografts (up to 36 mm in main body diameter) in the United States has resulted in significantly increased anatomic suitability for EVAR for large AAAs. Conversely, suitability has not significantly changed for small aneurysms. Our findings, therefore, suggest that larger endografts have expanded the window of opportunity for EVAR for large AAAs. The effectiveness and durability of EVAR with the use of such large endografts,

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Cited by (19)

In Vivo Evaluation of Customized Aortic Repair Using a Novel Survival Model
2016, European Journal of Vascular and Endovascular Surgery
Citation Excerpt :
However, endoleaks, endotension, stent graft migration, and device failure have contributed to a significantly higher rate of re-interventions and late aortic ruptures as well as higher mortality after 3 years with EVAR compared with open surgery.6–8 Moreover, tortuous or severely angulated aortic anatomy, insufficient proximal neck length, and large neck diameter remain outside the EVAR anatomic instructions for use criteria.9,10 To overcome the limitations of conventional open surgery and EVAR, alternative minimally invasive approaches have been developed for the treatment of AAA by filling the aneurysm sac.
The aim of the study was to evaluate the feasibility and mid-term biological behavior of the novel customized aortic repair (CAR) method for endovascular aneurysm treatment.
CAR consists of exclusion of an aneurysm from the circulation using a custom-designed dog bone-shaped balloon, followed by aneurysm sac filling with an in situ curing polymer. After curing and balloon deflation, the circulation is restored through a patent cast neolumen. A liquid two-component polymer was injected via a small bore catheter under X-ray control into a surgically created aneurysm. In 50% of the procedures, a self expanding bare metal stent was placed in the polymer cast lumen. A novel animal model was established involving creation of an aneurysm by anastomosing a venous interposition graft into the common carotid artery of eight adult sheep. Two animals were excluded because of non-device related complications. The remaining six animals were monitored for 20 weeks with duplex sonograms performed monthly to assess blood flow and polymer cast lumen patency. After the animals were sacrificed the polymer cast, common carotid artery, and the brain in the carotid outflow tract were removed for histological assessment.
In four of the six animals, the aneurysm was successfully excluded using CAR with uneventful follow up. The aneurysm sac was filled incompletely in two animals, resulting in a stent malpositioning and cast lumen occlusion after 12 weeks in one case, and a type 1 endoleak in the other. All six animals survived for 20 weeks. Neither migration nor expansion of the polymer cast was observed and the polymer was demonstrated to be biocompatible and non-thrombogenic. Polymer emboli were not detected in the brain or meninges after sacrifice.
The feasibility and mid-term biological safety of the CAR method for minimally invasive aneurysm repair was demonstrated using a simulated aneurysm survival model.
An analysis of variables affecting aortic neck length with implications for fenestrated endovascular repair of abdominal aortic aneurysm
2014, Annals of Vascular Surgery
Citation Excerpt :
Based on mortality (all cause and aneurysm-related), migration, endoleak, overall adverse events, and procedure-related complications, the literature shows disagreement that a wide proximal neck negatively affects suitability for EVAR.1,2,15,17,29 In addition, although there appears to be general agreement that short neck length negatively affects suitability for EVAR,1–3,5,9,14,15 there exists disagreement about specific end points, such as mortality, migration, and endoleak,3,6,8–10,16,17,30–33 that might be adversely affected by short neck length. The literature also indicates that a more angulated proximal neck can lead to migration and endoleak.6,7,12,28,30,34
A major factor in the selection of patients for endovascular aneurysm repair (EVAR) is the character of the aortic neck, and studies suggest that many patients are treated outside of the instructions for use (IFU) criteria. By analyzing aortic neck morphology, we hope to identify factors that may influence decision making about the use of fenestrated endografts as an alternative to extending the neck limitations of traditional endografts.
A retrospective analysis was completed on 111 patients who underwent computed tomography angiography (CTA) scans between May 1, 2009 and January 3, 2011 for the evaluation of abdominal aortic aneurysm (AAA). Individual characteristics of neck and aneurysm morphology were analyzed to establish whether certain factors determined suitability for EVAR with traditional nonfenestrated endografts. In considering augmented neck lengths (ANL), anatomic measurements of distance from the start of aortic dilatation to the lowest renal artery (LRA) and highest renal artery (HRA) were analyzed. Measurements were analyzed using Stata software (version 11.2; StataCorp, College Station, TX).
There were 86 men and 25 women in the patient population, with an average age of 72.9 years. In 46 patients, the proximal neck length was <15 mm, with 26 patients having neck lengths <10 mm. There was a negative relationship between AAA maximum diameter and proximal neck length (r_s = –0.2237; P = 0.018), indicating that as aneurysm size increases, proximal neck length decreases. There was a significant correlation between proximal neck length and proximal neck diameter (r_s = –0.2585; P = 0.006) and between proximal neck length and angle (r_s = –0.2355; P = 0.013), and between proximal neck diameter and right iliac maximum diameter (r_s = 0.2329; P = 0.014). Using fenestration to place an endograft above the LRA would create an ANL of >15 mm in 20 of 40 patients with aortic necks deemed too short to be eligible for EVAR using conventional infrarenal graft positioning. Extending the graft above the HRA would create an ANL of >15 mm in 36 of 40 patients.
In this study, 41% of patients presented with neck lengths outside that of the traditional IFU for most aortic endografts. While there was wide variation from patient to patient, there was a general correlation between increasing AAA size and aneurysms that have shorter, wider, and more angulated proximal necks. Fenestration of even 1 renal artery could substantially increase the ANL. Additional study is warranted to determine if an increase in ANL in patients with otherwise short necks will positively impact long-term EVAR outcomes.
Thrombogenicity of a new injectable biocompatible elastomer for aneurysm exclusion, compared to expanded polytetrafluoroethylene in a human ex vivo model
2012, European Journal of Vascular and Endovascular Surgery
Customized Aortic Repair (CAR) is a new concept for endovascular aortic aneurysm repair in which a non-polymerised elastomer is injected to fill the aneurysm sac around a balloon catheter. Amongst other variables, the thrombogenicity of the elastomer should be tested, before further clinical experiments can take place. The aim of this human ex vivo study was to measure the thrombogenicity of the elastomer and to compare it to expanded polytetrafluoroethylene (ePTFE).
In a validated ex vivo model, non-anticoagulated blood was drawn from the antecubital veins of 10 healthy donors with a 19-gauge needle. It was drawn through elastomer tubes and through ePTFE Gore-Tex vascular grafts, both 60 cm long and with an inner diameter of 3 mm.
Fibrinopeptide A (FPA) and P-selectin expression was measured in blood samples, collected at the end of the grafts. After the experiments, the deposition of platelets and fibrin onto the grafts was visualised by scanning electron microscopy.
For these graft types, a progressive increase in FPA production was observed in time. No significant difference was observed between the elastomer and ePTFE grafts (p > 0.05). No increase in P-selectin expression, and thereby no platelet activation, was observed in the perfusate of either grafts (p > 0.05). By scanning electron microscopy, numerous platelet aggregates were observed on the ePTFE grafts, whereas just a few adhered platelets and no aggregates were observed in the elastomer grafts.
The elastomer in its current formulation has a low thrombogenicity, comparable to ePTFE, making it an ideal substance for endovascular aneurysm sac filling. Further research should clarify the feasibility of CAR in vivo.
Development of off-the-shelf stent grafts for juxtarenal abdominal aortic aneurysms
2012, European Journal of Vascular and Endovascular Surgery
The use of EVAR for more complex aneurysm anatomy has become more widespread over the past decade. Fenestrated and branched stent grafts for the visceral and iliac segment show promising short- and midterm outcome and these procedures have become routine in many vascular centers. However, at present, such grafts are customized to the individual patient and planning and manufacturing leads to significant treatment delay subjecting the patients to the risk of rupture during the waiting period. The purpose of this report is to describe the first experience in treating juxta/suprarenal aneurysms using the first version of a new fenestrated stent graft
A fenestrated device was designed with two renal fenestrations, an SMA fenestration and a scallop for the coeliac artery. The renal arteries were designed with an inner 6 mm fenestration and an outer 15 mm diameter creating a dome to allow renal artery catheterization for a range of renal artery distribution. Seven patients with complex visceral artery anatomy were treated with customized stent grafts containing these pivot renal fenestrations.
Technical success was uniform with 100% target vessel catheterization and 0% 30-day mortality. In one case, the graft was displaced slightly during delivery resulting in a renal artery stent occlusion at 2 months postoperatively.
The development of a modified fenestrated device has shown this to be feasible and it has the potential to reduce the need for extensive preoperative graft customization and establishing a true off the shelf platform for juxta- and suprarenal AAA.
Physiologic component of the estimation of physiologic ability and surgical stress scoring system as a predictor of immediate outcome after elective open abdominal aortic aneurysm repair
2011, Annals of Vascular Surgery
Citation Excerpt :
Other issues also need to be considered so as to have the possibility of achieving a long-lasting and reintervention-free survival with an acceptable quality of life. It is noteworthy that physiologic fitness may not be as important for EVAR as it is for open procedures,19-21 but the aneurismal anatomic configuration may strongly influence the results. The Australian risk scoring system for EVAR takes into consideration not only the anatomic parameters but also age, ASA classification, gender, and creatinine level, demonstrating that physiologic fitness, specially age, may also influence outcome.22
Previous studies have shown a good predictive power of the risk scoring method, Estimation of Physiologic Ability and Surgical Stress, in predicting mortality after open elective aortic aneurysm repair. The aim of the present study was to evaluate the physiologic component of this method to assess mortality risk in a different geographic population from previously published reports.
Operative, morbidity and mortality data were collected retrospectively from charts of patients submitted to elective open repair of an abdominal aortic aneurysm over an 8-year period. There were 214 patients, the median age was 70 (range: 48-91) years; 179 (83.6%) patients were men. The Preoperative Physiologic Risk Score (PRS), Surgical Stress Score, and Comprehensive Risk Score (CRS) values were categorized and compared with morbidity and mortality rates.
There were 27 deaths (12.6%), and 81 (37.9%) patients experienced a postoperative complication that required medical intervention. There was a significant statistical difference for the values of PRS and CRS for patients who survived (0.53/0.63, respectively) and for those who died (0.88/1.02, respectively), p < 0.0001 for both values. There is a strong correlation between PRS and CRS values and development of complications (p < 0.0001). Surgical Stress Score did not correlate as strongly to development of complications (p = 0.0028). For PRS, the area under the receiver-operator characteristic curve was 0.844 (95% confidence interval: 0.747-0.941) for mortality and 0.725 (95% confidence interval: 0.650-0.799) for morbidity. For CRS, the area under the curve was 0.812 (95% confidence interval: 0.734-0.891) for mortality and 0.719 (95% confidence interval: 0.645-0.792) for morbidity. There was also a significant positive correlation between length of hospital stay and PRS and CRS scores (p < 0.0001). In this study, it was found that renal impairment has a significant positive correlation with mortality (p = 0.0008), with an odds ratio of 4.3. In a multivariate regression analysis, renal impairment failed to increase the accuracy of the model when associated with the other parameters considered in PRS.
This study corroborates with the previous findings that the Estimation of Physiologic Ability and Surgical Stress model seems to be a promising method of predicting death and postoperative complications in patients undergoing open abdominal aortic aneurysm repair.
Clinical practice guidelines for endovascular abdominal aortic aneurysm repair: Written by the standards of practice committee for the society of interventional radiology and endorsed by the cardiovascular and interventional radiological society of Europe and the Canadian interventional radiology association
2010, Journal of Vascular and Interventional Radiology
Citation Excerpt :
However, patients with insulin-controlled type 2 diabetes had lower rates of endoleaks and fewer secondary interventions than diet-controlled type 2 diabetic patients and nondiabetic patients (52). Regarding patient age and AAA repair, one study (53) has suggested that the mortality rate after open or endovascular AAA repair in carefully selected octogenarians seems acceptable but is higher than the mortality rate in younger patients, whereas another concluded (54) that EVAR suitability is not influenced by age, aneurysm size, or patient fitness. Additionally, one single-center study (55) cited significantly higher endoleak, open conversion, and renal infarction rates (P <.05) among a subgroup of patients older than 75 years, and also showed significantly elevated (P = .0011) aneurysm-related morbidity and mortality rates.

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: Presented at the 18th Annual Winter Meeting of the Peripheral Vascular Surgery Society, Snowmass Village, CO, February 1-3, 2008.

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Papers presented to the Peripheral Vascular Surgical Society–Winter 2008Influence of Age, Aneurysm Size, and Patient Fitness on Suitability for Endovascular Aortic Aneurysm Repair

Introduction

Section snippets

Methods

Results

Discussion

J Vasc Surg

J Vasc Surg

J Vasc Surg

J Vasc Surg

J Vasc Surg

J Vasc Surg

J Vasc Surg

J Vasc Surg

Morphologic changes and outcome following endovascular abdominal aortic aneurysm repair as a function of aneurysm size

Arch Surg

Papers presented to the Peripheral Vascular Surgical Society–Winter 2008
Influence of Age, Aneurysm Size, and Patient Fitness on Suitability for Endovascular Aortic Aneurysm Repair