Computed tomographic angiographic imaging of abdominal aortic aneurysms: implications for transfemoral endovascular aneurysm management

Analysis of brain tumour MRI with stress level using frequency analysis

The Computing science applied to determine the solutions for medical, science and business domain. The Data mining techniques used to identify the features and applied to solve the challenging issues in the domains. This work attempted to fetch the draw brain MRI and converted to computable format. The converted images are used form the frequent wave and classified based on the mode. The relationship between the stress level and affected brain neuron activeness relationship identified and presented as part of the paper . The result shows that the highly affected neurons stress levels are high.

Risk Factors, Dynamics, and Clinical Consequences of Aortic Neck Dilatation after Standard Endovascular Aneurysm Repair

OBJECTIVE

Aortic neck dilatation (AND) occurs after endovascular aneurysm repair (EVAR) with self expanding stent grafts (SESs). Whether it continues, ultimately exceeding the endograft diameter leading to abdominal aortic aneurysm (AAA) rupture, remains uncertain. Dynamics, risk factors, and clinical relevance of AND were investigated after EVAR with standard SESs.

METHODS

All intact EVAR patients treated from 2000 to 2015 at a tertiary institution were included. Demographic, anatomical, and device related characteristics were investigated as risk factors for AND. Outer to outer diameters were measured at a single standardised aortic level on reconstructed computed tomography (CT) images.

RESULTS

A total of 460 patients were included (median follow up 5.2 years, interquartile range [IQR] 3.0, 7.7 years; CT imaging follow up 3.3 years, IQR 1.3, 5.4). Baseline neck diameter was 24 mm (IQR 22, 26) and increased 11.1% (IQR 1.5%, 21.9%) at last CT imaging. Endograft oversizing was 20.0% (IQR 13.6, 28.0). AND was greater during the first year (5.2% [IQR 0, 11.7]) decreasing subsequently (two to four years to 1.4%/year [IQR 0.0, 4.5%], p ≤ .001) and was associated with suprarenal fixation endografts (t value = 7.9, p < .001) and oversizing (t value = 4.4, p < .001). AND exceeding the endograft was 3.5% (95% CI 2.2% - 4.8%) and 14.4% (95% CI 11.0% - 17.8%) at five and eight years, respectively. Excessive AND was associated with baseline neck diameter (OR 1.2/mm, 95% CI 1.05 - 1.41) while the Excluder endograft had a protective effect (OR 0.15, 95% CI 0.04 - 0.58). Excessive AND was associated with type 1A endoleak (HR 3.3, 95% CI 1.1 - 9.7) and endograft migration > 5 mm (HR 3.1, 95% CI 1.4 - 6.9).

CONCLUSION

AND after EVAR with SES is associated with endograft oversizing and radial force but decelerates after the first post-operative year. Baseline aortic neck diameter and suprarenal stent bearing endografts were associated with an increased risk of AND beyond nominal stent graft diameter. However, it remains unclear whether patient selection, differences in endograft radial force or the suprarenal stent are accountable for this difference.

Aneurysm Volumes After Endovascular Repair of Ruptured vs Intact Aortic Aneurysms: A Retrospective Observational Study

Purpose

To compare changes in abdominal aortic aneurysm (AAA) sac volume between endovascular aneurysm repairs (EVAR) performed for ruptured (rEVAR) vs intact (iEVAR) AAAs and to determine the impact of early volume shrinkage on future complications.

Materials and Methods

A retrospective analysis was performed of all patients undergoing standard infrarenal EVAR from 2002 to 2016 at a tertiary referral institution. Only patients with degenerative AAAs and with 30-day and 1-year computed tomography angiography (CTA) imaging were included. Early sac shrinkage was defined as a volume sac reduction >10% between the first (<30-day) and the 1-year CTA. The primary endpoint was to compare AAA sac volume changes between patients undergoing rEVAR (n=51; mean age 71.0±8.5 years; 46 men) vs iEVAR (n=393; mean age 72.3±7.5 years; 350 men). Results are reported as the mean difference with the interquartile range (IQR Q1, Q3). The secondary endpoint was freedom from aneurysm-related complications after 1 year as determined by regression analysis; the results are presented as the hazard ratio (HR) and 95% confidence interval (CI).

Results

At baseline, the rEVAR group had larger aneurysms (p<0.001) and shorter (p<0.001) and more angulated (p=0.028) necks. Aneurysm sac volume decreased more in the rEVAR group during the first year [−26.3% (IQR −38.8%, −12.5%)] vs the iEVAR group [−11.9% (IQR −27.5%, 0); p<0.001]. However, after the first year, the change in sac volume was similar between the groups [−3.8% (IQR −32.9%, 31.9%) for rEVAR and −1.5% (IQR −20.9%, 13.6%) for iEVAR, p=0.74]. Endoleak occurrence during follow-up was similar between the groups. In the overall population, patients with early sac shrinkage had a lower incidence of complications after the 1-year examination (adjusted HR 0.59, 95% CI 0.39 to 0.89, p=0.01).

Conclusion

EVAR patients treated for rupture have more pronounced aneurysm sac shrinkage compared with iEVAR patients during the first year after EVAR. Patients presenting with early shrinkage are less likely to encounter late complications. These parameters may be considered when tailoring surveillance protocols.

Total Luminal Volume Predicts Risk after Endovascular Aneurysm Repair

OBJECTIVE

Large aneurysm diameter represents a well known predictor of late complications after endovascular aneurysm repair (EVAR). However, the role of the thrombus free lumen inside the abdominal aortic aneurysm (AAA) sac is not clear. It was hypothesised that greater luminal volume represents a relevant risk factor for late complications after EVAR.

METHODS

A retrospective cohort analysis was performed including all patients undergoing EVAR from 2005 to 2016 at a tertiary referral institution. Pre-operative AAA lumen volume was measured in centre lumen line reconstructions and patients were stratified into quartiles according to luminal volume. The primary endpoint was freedom from AAA related complications. Secondary endpoints were freedom from neck events (type 1A endoleak, migration >5 mm or any pre-emptive neck related intervention), iliac related events (type 1B endoleak or pre-emptive iliac related intervention), and overall survival.

RESULTS

Four hundred and four patients were included: 101 in the first quartile (Q1; <61 cm³). Patients with higher luminal volumes had wider, shorter, and more angulated proximal necks. There were more ruptured AAAs, more aorto-uni-iliac implanted devices and patients outside neck instructions for use in the 4th quartile. Five year freedom from AAA related complications was 79%, 66%, 58% and 56%, respectively (p = .007). At five years, freedom from neck related events was 86%, 84%, 73%, and 71%, respectively, for the four groups (p = .009), and freedom from iliac related events was 96%, 91%, 88%, and 88%, respectively (p = .335). On multivariable analysis, luminal volume was an independent predictor of late complications (Q4 vs. Q1 - hazard ratio: 1.91, 95% confidence interval 1.01-3.6, p = .046). Overall survival at five years was not affected by lumen volume (p = .75).

CONCLUSION

AAA luminal volume represents an important risk factor for AAA related complications. This information may be considered when deciding tailoring surveillance protocols after EVAR. However, larger studies are needed to validate this hypothesis.

Long-term results after standard endovascular aneurysm repair with the Endurant and Excluder stent grafts

OBJECTIVE

Many endografts are currently available for standard endovascular repair of infrarenal abdominal aortic aneurysms. Comparison of long-term outcomes between devices might aid in this decision process, but comparative data are scarce. The purpose of this study was to report long-term clinical outcomes of two commercially available endoprosthesis, the Endurant (Medtronic Vascular, Inc, Minneapolis, Minn) and the Excluder (W. L. Gore & Associates, Flagstaff, Ariz) stent grafts.

METHODS

Patients undergoing standard endovascular repair from July 2004 to December 2011 in a single institution with the Endurant or the Low-Porosity Excluder endografts were eligible. Only patients treated for intact degenerative abdominal infrarenal aneurysms were included. All measurements were performed on center-lumen line reconstructions obtained on dedicated software. The primary end point was primary clinical success, defined as clinical success without the need for an additional or secondary surgical or endovascular procedure. Neck-related events (a composite of type IA endoleak, neck-related secondary intervention, or migration of >5 mm), neck morphology changes, renal function, and overall survival were secondary end points.

RESULTS

The study included 277 patients (156 Endurants; 121 Excluders). The median follow-up was 5.8 years (range, 0.1-12.4 years) and did not differ between groups (P = .18). Patients treated with the Endurant stent graft had wider (neck diameter of >28 mm, 27.3% vs 1.7% [P < .001]; neck diameter of 27 mm, [interquartile range (IQR), 24-29 mm] for Endurant and 24 mm [IQR, 22-25 mm] for Excluder; P < .001) and more angulated necks (β-angle of >60°, 26.7% vs 12.5%; P = .004). Oversizing was greater in the Endurant group (16% [IQR, 12%-22%] vs 13% [IQR, 8%-17%], respectively; P < .001). Patients were treated outside device instructions for use regarding proximal neck: 16.7% in the Endurant and 17.3% in the Excluder group (P = .720). The 7-year primary clinical success was 54.7% for the Endurant and 58.1% for the Excluder groups (P = .53). Freedom from neck-related events at 7 years was 76.7% for the Endurant and 78.8% for Excluder group (P = .94). The Endurant stent graft (hazard ratio [HR], 2.7; 95% confidence interval [CI], 1.3-5.8; P = .009) was an independent predictor of significant renal function decline. Neck dilatation was greater in Endurant-implanted patients (13% [95% CI, 2%-22%] vs 4% [95% CI, 0%-10%]; P < .001). Overall survival at 7 years was 61.4% in the Endurant and 50.3% (n = 50; standard error, 0.047) in the Excluder group (P = .39).

CONCLUSIONS

This study reveals that durable and sustainable results can be obtained with either of these late generation devices. This finding suggests that careful planning and a tailored device selection taking into account the patient's anatomy are more relevant determinants than the graft model itself to obtain clinical success. The Endurant endoprosthesis seems to be associated with a higher rate of neck dilatation and faster decrease in the estimated glomerular filtration rate, but further studies with longer follow-up are necessary to determine the clinical relevance of these findings.

Anatomic predictors for late mortality after standard endovascular aneurysm repair

OBJECTIVE

Abdominal aortic aneurysm (AAA) management involves a decision process that takes into account anatomic characteristics, surgical risks, patients' preferences, and expected survival. Whereas larger AAA diameter has been associated with increased mortality after both standard endovascular aneurysm repair (EVAR) and open repair, it is unclear whether survival after EVAR is influenced by other anatomic characteristics. The purpose of this study was to determine the importance of baseline anatomic features on survival after EVAR.

METHODS

All patients treated at a tertiary teaching center with EVAR for intact standard infrarenal AAA from 2000 to 2014 were included. The civil data registry was queried to determine survival status; causes of death were obtained from death certificates. The primary study end point was to determine the impact of baseline morphologic features on all-cause and cardiovascular mortality after EVAR.

RESULTS

This study included 404 EVAR patients (12.1% women; mean age, 73 years) with a median follow-up of 5.8 years (interquartile range, 3.1-7.4 years). The 5- and 10-year overall survival rates for the entire population after EVAR were 70% (95% confidence interval [CI], 66%-75%) and 43% (95% CI, 37%-50%), respectively. Only AAA diameter >70 mm (hazard ratio [HR], 1.75; 95% CI, 1.20-3.56) was identified as an independent anatomic predictor of all-cause mortality. Death due to cardiovascular causes occurred in 60 (38.5%) patients. Aneurysm-related mortality was responsible for six of the cardiovascular-related deaths. In multivariable analysis, both neck diameter ≥30 mm (HR, 2.16; 95% CI, 1.05-4.43) and AAA diameter >70 mm (HR, 2.45; 95% CI, 1.34-4.46) were identified as independent morphologic risk factors for cardiovascular mortality, whereas >25% circumferential neck thrombus (HR, 0.32; 95% CI, 0.13-0.77) was protective.

CONCLUSIONS

This study suggests that patients with AAA diameters >70 mm are at increased risk of all-cause and cardiovascular mortality. In addition, patients with infrarenal neck diameters ≥30 mm have a greater risk of cardiovascular mortality, although AAA-related deaths were not more frequent in this group of patients. Consequently, a more aggressive management of cardiovascular medical comorbidities may be warranted to improve survival after standard EVAR in these patients.

Evolution of the Proximal Sealing Rings of the Anaconda Stent-Graft After Endovascular Aneurysm Repair

Purpose: To provide insight into the evolution of the saddle-shaped proximal sealing rings of the Anaconda stent-graft after endovascular aneurysm repair (EVAR). Methods: Eighteen abdominal aortic aneurysm patients were consecutively enrolled in a single-center, prospective, observational cohort study (LSPEAS; Trialregister.nl identifier NTR4276). The patients were treated electively using an Anaconda stent-graft with a mean 31% oversizing (range 17–47). According to protocol, participants were to be followed for 2 years, during which 5 noncontrast electrocardiogram-gated computed tomography scans would be conducted. Three patients were eliminated within 30 days (1 withdrew, 1 died, and a third was converted before stent-graft deployment), leaving 15 patients (mean age 72.8±3.7 years; 14 men) for this analysis. Evolution in size and shape (symmetry) of both proximal infrarenal sealing rings were assessed from discharge to 24 months using dedicated postprocessing algorithms. Results: At 24 months, the mean diameters of the first and second ring stents had increased significantly (first ring: 2.2±1.0 mm, p<0.001; second ring: 2.7±1.1 mm, p<0.001). At 6 months, the first and second rings had expanded to a mean 96.6%±2.1% and 94.8%±2.7%, respectively, of their nominal diameter, after which the rings expanded slowly; ring diameters stabilized to near nominal size (first ring, 98.3%±1.1%; second ring, 97.2%±1.4%) at 24 months irrespective of initial oversizing. No type I or III endoleaks or aneurysm-, device-, or procedure-related adverse events were noted in follow-up. The difference in the diametric distances between the peaks and valleys of the saddle-shaped rings was marked at discharge but became smaller after 24 months for both rings (first ring: median 2.0 vs 1.2 mm, p=0.191; second ring: median 2.8 vs 0.8 mm; p=0.013). Conclusion: Irrespective of initial oversizing, the Anaconda proximal sealing rings radially expanded to near nominal size within 6 months after EVAR. Initial oval-shaped rings conformed symmetrically and became nearly circular through 24 months. These findings should be taken into account in planning and follow-up.

How Many Patients with Infrarenal Aneurysms are Candidates for Endovascular Repair? The Northern California Experience

Purpose:

To determine how many patients with abdominal aortic aneurysms (AAA) meet the anatomical selection criteria for AneuRx stent-graft repair in community hospitals of Northern California.

Methods:

The records were reviewed of 220 AAA patients (171 men, 49 women) who were considered for endovascular repair by the treating vascular surgeon at 28 community hospitals in Northern California between January and October 2001. Contrast computed tomographic angiography (CTA) and selective arteriography were performed at each institution and reviewed by a centralized, independent image-reading center. Selection criteria determined by the manufacturer and published in the indications for use were applied to each set of imaging studies. The number of patients who met inclusion criteria were recorded, as were the anatomical characteristics of each aneurysm.

Results:

The mean aneurysm size in the 220 patients was 55.3±0.7 mm. Among these patients, 122 (55%) were judged to be candidates for endovascular repair and 98 (45%) were considered ineligible. The primary anatomical reason for ineligibility was a short infrarenal neck in 43 (44%) patients, followed by a large proximal neck diameter (25, 25%), iliac aneurysms (10, 10%), extremely tortuous or calcified neck (7, 7%), iliac occlusion (6, 6%), and small distal aortic bifurcation and accessory renal arteries (5, 5%). Four (4%) patients were classified as non-candidates due to poor quality imaging. There was no difference in aneurysm diameter (54.0±0.8 versus 57.1±1.2 mm, p=NS) or age (72.2±1.2 versus 74.6±2.2 years, p=NS) between candidates and non-candidates. However, proportionally more men (60%) than women (39%) were eligible for endovascular repair with the AneuRx stent-graft (p<0.05). All 122 patients who were considered candidates for endovascular repair were treated, with successful stent-graft placement achieved in 121 (99%).

Conclusions:

Fifty-five percent of patients considered for endovascular AAA repair in community hospitals in Northern California met the anatomical selection criteria for the AneuRx stent-graft. Men appeared to be twice as likely to meet the eligibility requirements as women. Unfavorable infrarenal neck anatomy was the primary exclusion criterion for endovascular repair in this community setting.

Stent Graft Using Kilt Technique for an Abdominal Aortic Aneurysm with a Severely Angulated Neck

Endovascular aneurysm repair has become a standard treatment for abdominal aortic aneurysm (AAA). However a severely angulated aneurysmal neck is one of the most common anatomical limitations of endovascular repair, and is associated with poor outcomes. We successfully treated a patient who had an abdominal aortic aneurysm with a severely angulated aortic neck using kilt technique with thoracic stent graft. The technique might be an excellent alternative strategy to overcome anatomical obstacles like a hostile aortic neck.

Most Patients with Abdominal Aortic Aneurysm Are Not Suitable for Endovascular Repair Using Currently Approved Bifurcated Stent-Grafts

Strict morphologic criteria must be used for patient selection to achieve durable success with endovascular aortic aneurysm repair (EVAR). The goal of this study was to assess morphologic suitability (MS) of abdominal aortic aneurysms (AAAs) for 2 currently approved bifurcated stent grafts and identify reasons for exclusion from EVAR. The authors reviewed the electronic charts of 1,795 consecutive patients who were diagnosed as having AAA between January 1999 and July 2001 at their institution. Three hundred and twenty patients had an AAA with a diameter of =5.0 cm, measured on computed tomography (CT). The records of 301 patients, 254 men, 47 women, with a mean age of 74 years were available for review, and these patients constituted the study cohort. Criteria used for MS included a proximal neck length =15 mm; neck diameter between 18 and 26 mm; neck angulation =60°; common or external iliac artery (CIA or EIA) diameters of 7–16 mm and 8–13 mm, respectively, for AneuRx (Medtronic Ave, Santa Rosa, CA) and Ancure (Guidant Cardiac and Vascular Division, Menlo Park, CA) bifurcated grafts. AAAs were suitable for AneuRx device in 14% of patients (43 of 301; 95% CI = 11–19%) and for Ancure in 5% (16 of 301; 95% CI = 3.1–9%). The main reason for exclusion was an inadequate proximal aortic neck (73%). The neck was too short in 49.5%, too wide in 64% and badly angulated in 12% of the patients. Iliac artery morphology precluded EVAR with AneuRx and Ancure devices in 52% and 80%. Both CIAs were too wide for EVAR in 43% and 77%, respectively. When iliac artery diameter =20 mm was accepted, iliac suitability for AneuRx increased from 49% to 70% and overall suitability increased from 14% to 20%. When more permissive criteria were used for MS (neck length =10 mm, neck diameter =30 mm, CIA =20), 39% of patients became candidates for EVAR. More than three fourths of the patients with an AAA =5.0 cm in size, seen in a tertiary referral center, are morphologically not suitable for EVAR using 2 currently approved bifurcated endografts. The main reasons for exclusion are a short or wide proximal aortic neck. Considerable changes in size of the devices and in proximal attachment techniques have to occur before most AAAs will be suitable for EVAR.

Endovascular Repair of Abdominal Aortic Aneurysm Using the EVT Device: Limited Increased Utilization with Availability of a Bifurcated Graft

Purpose:

To determine if the availability of a bifurcated graft would increase the percentage of patients eligible for endovascular repair of abdominal aortic aneurysms (AAAs).

Methods:

One hundred eighty-five consecutive patients were evaluated prospectively for endovascular AAA repair at a university referral center. Data were collected on eligibility for tube or bifurcated endovascular grafts, reasons for exclusion, aneurysm morphology, and the interventions performed.

Results:

Forty-six (25%) patients were eligible for endovascular treatment using the first-generation Endovascular Technologies (EVT) system: 19 (10%) for a tube graft and 27 (15%) for a bifurcated device. An unsuitable proximal neck was the reason for exclusion in 48% of patients (excess diameter in 27%, inadequate length in 21%). Unsuitable iliac configuration was present in 41% of those excluded; 29% of the common iliac arteries were enlarged or aneurysmal, while 12% were small or tortuous.

Conclusions:

Although a bifurcated graft more than doubles the eligibility of AAA patients for endovascular repair, the configuration of the proximal neck and iliac disease excluded the majority of AAA patients from endovascular therapy using the first generation EVT device.

The influence of thrombus, calcification, angulation, and tortuosity of attachment sites on the time to the first graft-related complication after endovascular aneurysm repair

PURPOSE

Endovascular aneurysm repair (EVAR) is associated with high graft-related complication rates during follow-up. Anatomical fit between patient and endograft could be an important factor for successful treatment. Aim was to assess whether extent of thrombus, calcification, angulation, and tortuosity are associated with occurrence of complications after EVAR.

MATERIALS AND METHODS

Patients in either United Kingdom EVAR trial 1 or 2 were included if they had undergone EVAR within 6 months of randomization and had a preoperative computed tomography (CT) scan of adequate quality in the core laboratory. Three-dimensional CT imaging was used to assess extent of preoperative thrombus, calcification, angulation, and tortuosity in aneurysm neck and iliac segments. Cox regression modeling, adjusted for the variables tested and for known confounding variables, was used to investigate whether these factors were associated with increased rates of reported first complications.

RESULTS

A total of 217 patients with 53 first graft-related complications were analyzed after a mean follow-up of 3.6 years. Adjusted hazard ratios (95% confidence intervals, P values) for complications per unit increase of variable were 0.96 (0.92-0.99, 0.018) for neck thrombus, 1.06 (1.00-1.12, 0.044) for neck calcification, 1.02 (1.00-1.05, 0.079) for neck angulation, 1.04 (1.01-1.06, 0.011) for common iliac thrombus, 0.96 (0.93-1.00, 0.033) for common iliac calcification, and 5.96 (1.53-23.28, 0.010) for common iliac tortuosity.

CONCLUSION

Increased neck angulation and calcification and common iliac thrombus and tortuosity are associated with higher rates of graft-related complications after EVAR. Increased neck thrombus and common iliac calcification appear to protect against complications. Careful evaluation of these factors prior to EVAR might lead to lower complication rates.

Are multiplanar reconstructions necessary in routine body computed tomography practice?: what is the published evidence?

OBJECTIVE

During computed tomography interpretation, some anatomical regions are optimally displayed in planes other than axial. The purpose of this review was to define best interpretative practice, by demonstrating through literature review and case demonstration the computed tomography applications that should routinely include multiplanar viewing of the volume.

CONCLUSIONS

Owing to multidetector-row computed tomography technology, multiplanar reconstructions not only have become realistic and reliable but also, in some clinical settings, have been shown to improve diagnostic accuracy and interpretation speed.

Influence of Infrarenal Neck Length on Outcome of Endovascular Abdominal Aortic Aneurysm Repair

PURPOSE

To evaluate the influence of the infrarenal neck length on clinical outcome after endovascular abdominal aortic aneurysm repair (EVAR).

METHODS

Data were analyzed from 3499 patients enrolled in the EUROSTAR registry between January 1999 and April 2005 who underwent EVAR with a Talent or Zenith endograft and had detailed morphological data recorded. The study cohort was divided into 3 groups according to infrarenal neck length: >15 mm (reference group A, n=2822), 11 to 15 mm (group B, n=485), and < or =10 mm (group C, n=192). Uni- and multivariate analyses were performed to evaluate differences in clinical outcomes among the study groups.

RESULTS

After correction for confounders, proximal type I endoleak within 30 days occurred in 10.9% of group C compared to 2.6% of group A (OR 4.46, 95% CI 2.61 to 7.61). Within 48 months of follow-up (median 12 months), the incidence of proximal endoleaks was higher in groups B (9.6%; HR 1.98, 95% CI 1.16 to 3.38) and C (11.3%; HR 2.132, 95% CI 1.17 to 4.60) compared to group A (3.4%).

CONCLUSION

Our study indicates that endovascular treatment of abdominal aortic aneurysms with infrarenal neck length <15 mm is associated with significantly increased risk of short- and midterm proximal endoleaks after EVAR. The greater risk of proximal endoleaks should be weighed against the risks of alternative treatment modalities.

Consistency in endovascular aneurysm repair suitability assessment requires group decision audit

INTRODUCTION

Proper selection of patient and stent-graft combinations in endovascular aneurysm repair (EVAR) depends on knowledge and experience with the different types of stents that have to be adapted to the patient's unique abdominal aortoiliac anatomy. The aim of this study was to analyze the consistency and variance in EVAR suitability assessment between clinicians.

METHODS

Worksheets that contained anatomic data derived from computed tomography scans and angiography were compiled for 202 patients. Five clinicians, all experienced in EVAR surgery, assessed the anatomic data on the worksheets for suitability for three types of stent-grafts. The obtained 3030 assessments represented a quantification of the likelihood of success the clinician expected for effective and durable sealing and fixation of the stent-graft in EVAR. The Delphi method was used to determine consensus in the thinking process among clinicians, and kappa analysis was used to determine the proportion of variances in the assessment result between clinicians.

RESULTS

With the Delphi method, Cronbach alpha values of 0.87, 0.87, and 0.90 were reached for the three types of stent-grafts in the second assessment round. The individual clinician-group correlation in round two was between 0.69 and 0.86 for clinicians 1, 2, 3, and 4. Between clinician 5 and the others, correlation varied between 0.43 and 0.64. The kappa values ranged between 0.32 and 0.51 among clinicians 1, 2, and 3. Between clinician 5 and the others, kappa values between 0.08 and 0.29 were reached.

CONCLUSION

EVAR suitability estimation in a cohort of patients is highly consistent in a group of experienced clinicians. The EVAR suitability estimation at the individual patient level varies substantially between clinicians, however. Aggregating expert opinions in abdominal aortic aneurysm anatomic suitability assessment for EVAR had the opportunity to replace individual clinician decision diversification in a more solid and consistent group decision process.

Endovascular repair of abdominal aortic aneurysms: CTA evaluation of contraindications

Endovascular aortic aneurysm repair (EVAR) is considered an acceptable alternative to open surgery in selected patients. Its feasibility depends mainly on anatomic factors that represent the important predictors of success and the most important exclusion criteria. Poor anatomic patient selection is generally associated with a higher risk for procedural complications and compromised long-term outcomes. Therefore pretreatment imaging is crucial for evaluating patient suitability for EVAR. Multidetector computed tomographic angiography represents the current standard of reference in the evaluation of the abdominal aorta and iliac axis anatomy because it provides all the details needed for selection of patients who are suitable for endograft and the choice of the appropriate device. This report identifies and reviews computed tomographic angiographic anatomic contraindications for EVAR.

Suprarenal Endograft Fixation Avoids Adverse Outcomes Associated with Aortic Neck Angulation

The advent of endovascular therapy has had a profound impact on repair of abdominal aortic aneurysms (AAA). Prudent patient selection, particularly in regard to unfavorable anatomy, is emerging as perhaps the most important determinant of endovascular abdominal aortic aneurysm repair (EVAR) outcome. The aim of this study was to examine the association of one such anatomic factor, proximal aortic neck angulation, with the incidence of adverse events following EVAR. Prospectively collected data on 289 EVAR repairs with the Talent endograft (Medtronic, Inc., Minneapolis, MN) from March 1998 to June 2000 were analyzed. Stent graft-specific adverse events studied were migration, endoleak, kinking, thrombosis, and AAA expansion. Computed tomography (CT) scanning with three-dimensional post-processing and/or aortography was used to measure aortic neck angle. Patients were categorized into one of four groups according to their neck angle: I (0-10 degrees); II (11-39 degrees); III (40-59 degrees); or IV (60-85 degrees). Outcomes were evaluated by chi-squared analysis and ANOVA. There was a direct correlation between AAA diameter and neck angle (p = 0.002). There was no difference in endoleak rate (p = 0.877), stent migration (p = 0.850), or AAA expansion rate (p = 0.599) between groups. Device kinking >45 degrees was associated with neck angulation > or = 60 degrees (p = 0.013), but not with other adverse outcomes. The average neck angle was 30 degrees in patients with endoleaks and 31 degrees in patients without endoleaks. Increasing aortic neck angulation was not associated with the selected adverse outcomes within 1 year following EVAR with the Talent stent graft using suprarenal fixation with the exception of graft kinking. This may be related to the graft design that permits suprarenal aortic fixatiou of the proximal stent graft, Whether severe degrees of angulation of 60 degrees or greater can be safely treated with suprarenal fixation requires further study.

Ruptured Abdominal Aortic Aneurysm: Endovascular Repair is Feasible in 40% of Patients

INTRODUCTION

Open repair of ruptured abdominal aortic aneurysm (rAAA) still has a high mortality. Endovascular aortic repair (EVAR) may be the way to improve survival rates. However, it is not clear how many patients with rAAA will be suitable for acute EVAR.

METHODS

Between October 2000 and April 2002 all patients with acute symptomatic or ruptured AAA were assessed for EVAR on an intention-to-treat basis with emergency computed tomographic angiography (CTA). Patient and logistic characteristics were analysed. We used two commercially available aorto uni-iliac devices with a maximum proximal diameter of 28 and 34 mm.

RESULTS

Five out of 26 patients were excluded for CTA and EVAR because of severe and persistent hypotension (3 pts) or logistic reasons (2 pts, both eligible). Twelve patients were found not eligible for EVAR due to unsuitable infrarenal aortic neck length (3 pts), neck diameter (1 pt) or a combination of both (8 pts). The remaining six patients were treated with EVAR. After 6 months no graft failure or aneurysm related deaths were recorded in the EVAR group.

CONCLUSION

A total of 28% of patients with symptomatic or ruptured AAA was treated with EVAR. A potential 42% of patients could have been suitable for EVAR, if the correct devices had been in stock and all patients had been properly assessed.

Does hostile neck anatomy preclude successful endovascular aortic aneurysm repair?

OBJECTIVES

Poor outcomes have been reported with endovascular aneurysm repair (EVAR) in patients with hostile neck anatomy. Unsupported endografts with active fixation may offer certain advantages in this situation. We compared EVAR results using the Ancure (Guidant) endograft in patients with and without hostile neck anatomy.

METHODS

Records of EVAR patients from October 1999 to July 2002 at a tertiary care hospital were retrospectively reviewed from a division database. Patients with elective open abdominal aortic aneurysm (AAA) repair during the same period were reviewed to determine those unsuitable for EVAR. Hostile neck anatomy, assessed by computer tomography (CT) scans and angiograms, was defined as one or more of the following: (1) neck length </=10 mm, (2) focal bulge in the neck >3 mm, (3) >2-mm reverse taper within 1 cm below the renal arteries, (4) neck thrombus > or =50% of circumference, and (5) angulation > or =60 degrees within 3 cm below renals.

RESULTS

Three hundred and twenty-two patients underwent EVAR with an average follow-up of 18 months. Patients in Phase II trials (n = 41), repaired with other graft types (n = 48), or without complete anatomic records (n = 27) were excluded. Demographics and co-morbidities were similar in the 115 good-neck (GN) and 91 bad-neck (BN) patients except for age (mean, 72.9 years GN vs 75.7 BN; P = 0.13), gender (11% female GN vs 22% BN; P =.04); neck length (mean, 21.8 mm GN vs 14.4 mm BN: P <.001), and angulation (mean, 22 degrees GN vs 40 degrees BN; (P <.001). Perioperative mortality (0 GN vs 1.1% BN), late mortality (5.2% GN vs 4.4% BN), all endoleaks (19.1% GN vs 17.6% BN), proximal endoleaks (0.8% GN vs 2.1% BN), and graft migration (0 for both groups) did not reach statistical significance. Neck anatomy precluded EVAR in 106 of 165 (64%) patients with open AAA.

CONCLUSIONS

Unsupported endografts with active fixation can yield excellent results in treating many medically compromised patients with hostile neck anatomy. Nonetheless, an unsuitable neck remains the most frequent cause for open abdominal AAA.

Endovascular aneurysm repair with a bifurcated endovascular graft at a primary referral center: Influence of experience, age, gender, and aneurysm size on suitability

OBJECTIVE

The purpose of this study was to assess the suitability for endovascular repair of abdominal aortic aneurysm (EVAR) in an unselected patient population.

PATIENTS AND METHODS

Between February 1999 and May 2002 all consecutive patients with a nonemergent abdominal aortic aneurysm (AAA) were prospectively examined with contrast material-enhanced spiral computed tomography (CT). Those patients probably suitable for EVAR on the basis of CT findings underwent calibrated angiography. A panel of radiologists and vascular surgeons reviewed the clinical data and vascular anatomy, and decided on the appropriateness of EVAR with the bifurcated Zenith AAA endovascular graft.

RESULTS

One hundred seven patients were included. Fifty-six patients (52%) had one or more contraindications for EVAR. Unsuitability was most frequently (88%) related to the proximal neck. Inadequate neck length was the most common specific reason. Inadequate iliac anatomy was the reason for unsuitability in 59% of patients. The rate of unsuitability decreased from 61% during the first half of the study to 40% during the second half (P =.03) Unsuitability was equal between men and women. Age and maximum diameter did not differ between candidates and noncandidates.

CONCLUSION

Almost half (48%) of patients with an infrarenal AAA referred to a primary referral center are suitable for EVAR with the bifurcated Zenith AAA endovascular graft. Neck anatomy was the most frequent reason for rejection. Rate of suitability increased over time, probably as a result of increasing experience. Suitability was not influenced by gender, age, or aneurysm size.

Anatomical suitability of ruptured abdominal aortic aneurysms for endovascular repair

PURPOSE

To assess the anatomical suitability of ruptured abdominal aortic aneurysms (AAA) for emergency endovascular repair.

METHODS

All cases (46 patients [35 men; mean age 74 years, range 54-85]) in which computed tomographic angiography (CTA) confirmed AAA rupture over a 5-year period at our university hospital were reviewed for anatomical suitability for endovascular repair. Measurements were made by a radiologist experienced in anatomical assessment of CT criteria for elective endovascular aneurysm repair (EVAR).

RESULTS

The mean aneurysm neck length was 18 mm (range 0-59); 17 were conical, 13 straight, 4 barrel, and 6 reverse conical. Six cases had no proximal neck. Overall, 37 (80%) patients were unsuitable for EVAR according to our criteria. Nearly half the patients (22, 48%) had > or =2 adverse features. Unsuitable neck morphology (35, 76%) was the primary reason for exclusion, but CIA aneurysm (10, 22%) and EIA tortuosity (7, 15%) were secondary adverse features.

CONCLUSIONS

With current stent-graft design, the majority of ruptured abdominal aortic aneurysms are anatomically unsuitable for endovascular repair.

Durability of aortouniiliac endografting with femorofemoral crossover: 4-year experience in the Evt/Guidant trials

OBJECTIVES

We evaluated mid-term results of the multicenter EVT/Guidant aortouniiliac endograft (AI) trial and ascertained the durability of this endovascular technique in patients unable to undergo standard bifurcated endografting.

METHODS

From November 1996 to December 1998, 121 patients were enrolled to receive the AI device on the basis of complex iliac artery anatomy contraindicating bifurcated endografting. Clinical data were centrally collected, and radiographic data were evaluated by core facility.

RESULTS

AI placement was technically successful in 113 of 121 patients. At operation, patients who underwent AI had significantly more arrhythmias, congestive heart failure, and peripheral occlusive disease (P <.05) compared with patients who underwent open aneurysmorrhaphy in the EVT/Guidant trials, indicating comorbid features in this anatomic cohort. Distal AI attachment was performed to the external iliac artery in 40 (36%) patients. Median follow-up was 38 months. In the AI group, overall aneurysm diameter decreased over the duration of study from 54.4 +/- 9.6 mm to 44.4 +/- 16.4 mm (P =.004). At 24 and 36 months after repair, reduction in aneurysm size was associated with absence of endoleak (P =.003 and P =.008, respectively). Aneurysms shrunk or remained stable in 109 (96.5%) patients. Endoleak was identified in 52.3% of patients at discharge, and at follow-up in 30.9% at 1 year, 34.8% at 2 years, 28.6% at 3 years, and 30.4% at 4 years. Type II endoleak predominated. Leak from failure to completely occlude contralateral iliac flow accounted for 8 of 58 endoleaks (13.8%) at discharge. Sixteen patients (14.2%) underwent postoperative endoleak treatment; in one of these patients open conversion was necessary at 20 months. Post-procedure thigh or buttock claudication developed in 16 patients (14.2%). Thirteen patients (81.3%) had either distal attachment in the external iliac artery or contralateral type IIA occlusion. Fifteen patients (13.3%) required intervention because of reduced limb flow; one of these patients underwent open conversion at 27 months, and another underwent axillofemoral grafting at 28 months. Device migration was confirmed in 2 (1.8%) patients, without current clinical sequelae. Whereas no femorofemoral graft thromboses occurred, graft infection developed in 3 patients (2.6%). During follow-up, aneurysm in 2 patients ruptured. Late death occurred in 41 patients (36.3%). Twenty-four patients (58.5%) died of cardiopulmonary disease; one death was endograft-related after aneurysm rupture; and one death was related to femorofemoral bypass infection. Actuarial survival was 78.4% (95% confidence interval [CI], 71%-86%) at 2 years and 63.4% (95% CI, 54%-73%) at 4 years.

CONCLUSIONS

In patients with significant comorbid conditions and complex iliac anatomy unfavorable for bifurcated endografting, AI with femorofemoral bypass grafting is safe and effective. In most patients this endovascular option provides satisfactory mid-term results.

IVUS guidance of thoracic and complex abdominal aortic aneurysm stent-graft repairs using an intracardiac echocardiography probe: preliminary report

PURPOSE

To report our learning experience using an intracardiac echocardiography (ICE) probe to guide endovascular aortic procedures.

METHODS

Between November 1999 and July 2001, 17 patients (12 men; mean age 73.1+/-2.3 years) underwent endovascular repair of 9 thoracic, 6 complex abdominal, and 2 thoracoabdominal aortic aneurysms. The most suitable dimensions and configuration of the stent-graft were based on preoperative computed tomographic (CTA) or magnetic resonance (MRA) angiography. Intraoperative intravascular ultrasound (IVUS) imaging was obtained using a 9-F, 9-MHz ICE probe, 110 cm in length, inserted through a 10-F, 55 degrees precurved long polyethylene sheath.

RESULTS

The endografts were deployed as planned by CTA or MRA. Before stent-graft deployment, interrogation with the ICE probe visualized the aortic arch and descending thoracoabdominal aorta without position-related artefacts and identified the sites of stent-graft fixation. After stent-graft deployment, visualization with the ICE probe detected the need for additional procedures in 8 patients, including 2 incompletely expanded thoracic grafts, which were treated with adjunctive balloon angioplasty. In 1 patient, ICE probe interrogation determined that the lesion was inappropriate for endovascular exclusion.

CONCLUSIONS

ICE probe interrogation provides accurate information on the anatomy of thoracic and abdominal aortic aneurysms and allows rapid identification of attachment sites and stent-graft characteristics. It might be considered as a valid imaging modality for monitoring all phases of endovascular procedures.

Initial results of endovascular repair of abdominal aortic aneurysms with a self-expanding stent-graft

PURPOSE

This study was performed to evaluate the authors' experience with the endovascular treatment of abdominal aortic aneurysm (AAA) with use of a self-expanding nitinol stent covered with a polyester fabric device and to report the implant's technical features, the immediate results, and the outcome 30 days after device implantation.

MATERIALS AND METHODS

From June 1997 to December 2001, we admitted 169 patients diagnosed with AAA. Of these, 134 were suitable to undergo endovascular repair with use of the Talent stent-graft. In one patient, it was technically impossible to proceed with the implantation procedure. Therefore, a total of 133 patients were treated with use of this technique (78.7%). The average age was 70.7 years (range, 52-88 y). There were 119 men and 14 women. Computed tomographic follow-up was done between the 15th and 30th postoperative days.

RESULTS

The stent-grafts were successfully implanted in all 133 patients. Complications during the procedure included three type-I endoleaks (2.3%) and four iliac artery ruptures (3.0%), which were effectively treated by means of aortic or iliac extension grafts, respectively. The average surgical time was 2.92 hours (from 1.67 h to 7 h). Of the stent-grafts used, 125 were bifurcated (94.0%), two were straight tube grafts (1.5%), and six were conical aortouniiliac grafts (4.5%). Custom-made grafts were used in 62 patients (46.6%) and standard grafts were used in 71 (53.4%). Suprarenal fixation was performed in 117 patients (88%). One female patient developed a serious pulmonary embolism. Eight patients (6.0%) developed serious systemic inflammatory syndrome; two died of disseminated intravascular coagulopathy. There were two additional deaths, one from refractory shock and one suddenly from an unknown cause (total mortality rate, 3.0%). During the postoperative period, 70.3% of the patients developed mild fever (37.6 degrees C-38.9 degrees C). The average length of stay in the intensive care unit was 1.3 days (ranging from 1 d to 12 d) and the total hospitalization time was 4.2 days. Six type-II endoleaks were observed: two were corrected by video laparoscopy-assisted inferior mesenteric artery interruption and the other four were clinically followed up.

CONCLUSIONS

The exclusion of AAA by endovascular techniques with use of the Talent device was possible in the majority of cases with a low incidence of complications. The most common serious postprocedural complication was systemic inflammatory syndrome.

Stent-graft migration following endovascular repair of aneurysms with large proximal necks: anatomical risk factors and long-term sequelae

PURPOSE

To evaluate the outcome of aortic endografts deployed in large infrarenal necks and to identify any association of preoperative aneurysm characteristics and postoperative morphological changes with the incidence of neck dilatation and device migration in this patient subset.

METHODS

The records of 47 patients (41 men; mean age 74, range 55-84) with large aortic neck diameters treated with Talent stent-grafts from 1998 to 2001 were reviewed. Patients with anatomical criteria that precluded aneurysm exclusion with currently available devices were preferentially selected. Mean baseline aneurysm morphology included 27.6-mm (range 18-33.4) suprarenal and 28.1-mm (range 24-34) infrarenal neck diameters; the infrarenal neck length was 26 +/- 16 mm with angulation of 37 degrees +/- 18 degrees. Computed tomographic (CT) angiograms up to 3 years were analyzed using specialized interactive software; migration was defined as >1-cm change in the distance from the lower renal artery to the top of the device. Pre- and postoperative morphological characteristics of the aneurysm were compared between patients with and without migration.

RESULTS

Of the 45 patients successfully treated, 40 had complete CT data for analysis. During a mean 17-month follow-up, 7 (17.5%) of the 40 devices exhibited distal migration. Six patients required secondary procedures; 5 were in the migration cohort. No preoperative anatomical characteristic or degree of neck dilatation over time was predictive of stent-graft migration. Aneurysm sac regression was significant at 1 (-0.09 +/- 4.90 mm) and 2 (-1.48 +/- 2.56 mm) years in endografts without migration (p<0.001). Distal endograft migration >1 cm predicted the need for secondary interventions (p<0.001), with 83% sensitivity and 94% specificity.

CONCLUSIONS

Endovascular repair is successful in patients with large infrarenal necks and complex neck morphology. Changes in aneurysm remodeling over time were similar to reported observations in patients with more favorable neck criteria. Although no anatomical factor associated with migration could be identified from this analysis, distal displacement >1 cm correlated with the need for a secondary intervention.

Exclusion of accessory renal arteries during endovascular repair of abdominal aortic aneurysms

OBJECTIVE

Adequate proximal neck length is important for proper endovascular treatment of abdominal aortic aneurysms (AAAs). Placement of endografts in AAAs with relatively short proximal necks may require covering the origin of accessory renal arteries. Exclusion of these arteries carries the theoretical concern of regional renal ischemia associated with loss of parenchyma or worsening hypertension. We reviewed our experience with accessory renal exclusions during endovascular AAA repair to determine the frequency and severity of complications.

METHODS

Complete records were available for review on 311 of 325 consecutive patients treated with endovascular grafts for AAAs from February 6, 1996, to March 15, 2001. The presence of accessory renal arteries was ascertained from preoperative/intraoperative aortography or from computed tomographic scanning. Sizes of the accessories were measured by using the main renal arteries as a reference. Considerations for excluding the accessory renal arteries were based on the likelihood of successful proximal attachment to healthy aorta, an accessory vessel whose size does not exceed the diameter of the main renal artery, and the absence of renal disease.

RESULTS

The mean follow-up was 11.5 months. Fifty-two accessory renal arteries were documented in 37 patients (12%), ranging from 1 to > or =3 per patient. Of these, 26 accessory renal arteries were covered in 24 patients. Patients ranged in age from 57 to 85 years (mean, 74.1 years), with 20 men and 4 women. The Ancure device was used in 23 patients and the Excluder device in one. Of the accessories excluded, 22 originated above the aneurysm and 4 originated directly from the aneurysm itself. There were no perioperative mortalities. One patient died 5 months after surgery from an unrelated condition. There was one type I (distal) endoleak and no type II endoleaks. Five patients (21%) had segmental renal infarction associated with the side of accessory renal artery exclusion. Only one patient with segmental infarction had significant postoperative hypertension that resulted in changes in blood pressure medication. The blood pressure reverted to normal 3 months later. One patient with a stenotic left main renal artery required exclusion of the accessory renal artery for successful proximal attachment. Serum creatinine levels remained unchanged throughout follow-up in all but one patient, in whom progressive postoperative renal failure developed despite normal renal flow scan, presumably from intraoperative manipulation and contrast nephropathy.

CONCLUSION

Exclusion of accessory renal arteries to facilitate endovascular AAA repair appears to be well tolerated. Long-term sequelae seem infrequent and mild.

Abdominal aortic aneurysms before and after endograft implantation: evaluation by computed tomography

The evaluation of patients with abdominal aortic aneurysms for endograft candidacy and their follow-up after treatment are heavily dependent on radiologic imaging. Factors never considered during conventional open repair have become crucial to patient selection and procedural success, and the new and developing nature of the field of endovascular repair necessitates close surveillance of these devices after deployment. Computed tomography (CT) has emerged as the single most effective imaging tool for the preprocedural assessment and subsequent follow-up of these patients. This article outlines the technical parameters for obtaining pre- and postoperative CT examinations in endograft patients and discusses the important imaging findings.

Automatic morphology-based brain segmentation (MBRASE) from MRI-T1 data

A method called morphology-based brain segmentation (MBRASE) has been developed for fully automatic segmentation of the brain from T1-weighted MR image data. The starting point is a supervised segmentation technique, which has proven highly effective and accurate for quantitation and visualization purposes. The proposed method automates the required user interaction, i.e., defining a seed point and a threshold range, and is based on the simple operations thresholding, erosion, and geodesic dilation. The thresholds are detected in a region growing process and are defined by connections of the brain to other tissues. The method is first evaluated on three computer simulated datasets by comparing the automated segmentations with the original distributions. The second evaluation is done on a total of 30 patient datasets, by comparing the automated segmentations with supervised segmentations carried out by a neuroanatomy expert. The comparison between two binary segmentations is performed both quantitatively and qualitatively. The automated segmentations are found to be accurate and robust. Consequently, the proposed method can be used as a default segmentation for quantitation and visualization of the human brain from T1-weighted MR images in routine clinical procedures.

Three-dimensional intravascular ultrasound assessment of abdominal aortic aneurysm necks

PURPOSE

To document the accuracy of an automated analysis system for measuring lumen diameter and neck lengths of abdominal aortic aneurysms (AAAs) from intravascular ultrasound (IVUS) images and to describe additional features associated with 3-dimensional (3D) IVUS imaging.

METHODS

Twenty-two aortic aneurysms were studied with IVUS. Lumen diameters obtained using the automated analysis system were compared with manual measurements from axial IVUS scans, as were neck lengths obtained using automated analysis versus those measured with the aid of a displacement sensing device. Automated analyses were repeated by a second observer. Agreement was expressed as the coefficient of variation (CV).

RESULTS

Twenty proximal aortic, 6 distal aortic, and 3 iliac necks were available for analysis. Comparison between automated analysis and manual measurements for lumen diameter revealed a difference of 0.45 +/- 0.42 mm (mean +/- SD, Pearson's r = 0.99, p < 0.001, CV = 2.1%) and a difference of 0.05 +/- 0.12 cm (r = 0.99, p = 0.04, CV = 4.1%) for neck length. Interobserver difference for lumen diameter was 0.13 +/- 0.66 mm (r = 0.99, p < 0.001, CV = 3.4%) and 0.05 +/- 0.11 cm for length measurements (r = 0.99, p = 0.02, CV = 3.5%). The 3D IVUS imaging facilitated the identification of neck configuration.

CONCLUSIONS

Automated analysis of IVUS images allows accurate measurement of the lumen diameter of proximal and distal AAA necks and gives length measurements comparable to those of manual analysis. Longitudinal display of IVUS images aids in the elucidation of neck anatomy.

Endovascular repair of abdominal aortic aneurysms: eligibility rate and impact on the rate of open repair

OBJECTIVE

The purpose of this study was to determine the rate of eligibility among patients with abdominal aortic aneurysms (AAAs) considered for endovascular repair and to examine the effect of an endovascular program on the institutional pattern of AAA repair.

METHODS

All patients evaluated for endovascular AAA repair since the inception of an endovascular program were reviewed for determination of eligibility rates and eventual treatment. Open AAA repairs were categorized as simple (uncomplicated infrarenal), complex (juxtarenal, suprarenal, thoracoabdominal, infected), or ruptured, and their rates before and after initiation of an endovascular program were compared.

RESULTS

Over 3 years, 324 patients were considered for endovascular AAA repair; 176 (54%) were candidates, 138 (43%) were not candidates, and 10 (3%) did not complete the evaluation. The rate of eligibility increased significantly from 45% (66/148 patients) during the first half of this period to 63% (110/176 patients) during the second half (P <. 001). Candidates were significantly younger (74.4 +/- 7.6 years) than noncandidates (78.3 +/- 6.7 years) (P <.01), and their aneurysm diameter tended to be smaller (57.6 +/- 9.2 mm compared with 60.8 +/- 12.3 mm; P =.06). The most common reason for ineligibility was an inadequate proximal aortic neck. Of 176 candidates, 78% underwent endovascular repair, and 6% underwent open repair. Of 138 noncandidates, 56% underwent surgical repair. Over a period of 6 years, 542 patients with AAAs (429 simple, 86 complex, 27 ruptured) underwent open repair. The total number and ratio of simple to complex open repairs for nonruptured aneurysms during the 3 years before the initiation of the endovascular program (213 simple, 44 complex) were not significantly different from the repairs over the subsequent 3-year period (216 simple, 42 complex). Similarly, no difference in the total number and the ratio of simple to complex open repairs was found between the first and the second 18-month periods since the initiation of the endovascular program.

CONCLUSIONS

The rate of eligibility of patients with AAA for endovascular repair appears to be higher than previously reported. The presence of an active endovascular program has not decreased the number or shifted the distribution of open AAA repair.

Transrenal fixation of aortic endografts: intermediate follow-up of a single-center experience

PURPOSE

To examine the fate of the renal ostia following transrenal fixation of endovascular aortic stent-grafts.

METHODS

Thirty-five patients (29 men; mean age 75 years) undergoing endovascular repair for abdominal aortic aneurysms (AAAs) had transrenal fixation of the uncovered proximal stent due to a short (< 1.5 cm long) or conical neck or a periprocedural endoleak. Eighteen (51%) patients were hypertensive; 7 (20%) had renal artery stenoses (RAS). Outcome measures included blood pressure, serum creatinine, computed tomography, and renal artery duplex scans.

RESULTS

Two patients with > or = 60% RAS had renal stents placed during the endograft procedure; the other 5 RAS patients were normotensive and their renal lesions were not treated. Overall technical success was 82.9% (29/35). One (2.9%) case was converted due to graft twisting. There were 5 (14.2%) early endoleaks. Transient postoperative creatinine elevations were observed in 5 (14.2%) cases. Over a median 11-month period (range 2-24), no secondary endoleaks or silent renal artery occlusions were seen. One normotensive patient with an untreated > or = 60% renal lesion developed hypertension and severe stenosis (99%) at 4 months; stenting through the interstices of the transrenal stent was performed. No disease progression was seen in the other 6 RAS patients.

CONCLUSIONS

In the intermediate period, transrenal fixation appears to have no adverse effects on renal blood flow. Moreover, in patients with no evidence of renal disease or preoperative RAS < 60%, it does not precipitate or cause progression of renal stenosis. However, patients with preoperatively documented RAS > or = 60% are a concern and mandate further study.

Predictive factors for early success of endovascular abdominal aortic aneurysm repair

To identify predictive factors for postoperative success and potential predictors for satisfactory outcome of endovascular grafting for abdominal aortic aneurysm (AAA), we collected data from our prospective database, which includes a series of consecutive patients undergoing endovascular repair at the Vascular Surgery Unit, Policlinico Monteluce, Perugia, Italy. From April 1997 to July 1998, 202 patients were referred to our Unit for elective AAA repair; 94 patients (47%) were selected for endografting. Placement of the graft using endovascular technique without conversion to open laparotomy, in addition to no mortality, major morbidity, or endoleak at 30-day follow-up, was defined as postoperative success. The influence of anatomical features on postoperative results was analyzed by univariate and multivariate analysis. Our experience shows that endoluminal repair of AAA is safe and effective in the short term and male patients with small aneurysms are optimal candidates for successful repair.

The value of intraoperative intravascular ultrasound for determining stent graft size (excluding abdominal aortic aneurysm) with a modular system

Since the introduction of endovascular stent grafts at our institution we have used intraoperative intravascular ultrasound (IVUS) to definitively determine stent graft size. In this study, expected stent graft size, based on preoperative helical CT scan measurements, was compared with the actual final size, based on intraoperative IVUS measurements. Between December 1996 and January 1998, 54 patients were treated with an AneuRxTM bifurcated stent graft. Preoperatively all patients underwent angiography and helical CT scanning. Expected stent graft size was determined according to these measurements. The final stent graft size was based on IVUS measurements acquired during the procedure. Differences in expected and final size were compared and follow-up endoleaks were also noted. Differences in diameter measurements between CT and IVUS were compared using the paired Student's t-test. Differences in expected and chosen stent graft length were compared using the McNemar's test for paired proportions of binomial outcomes. Our results showed that helical CT scanning overestimates diameter and underestimates length. This underestimation of length is explained by the tortuosity of the aorta and iliac arteries while using axial slices of the CT scan. The last-minute corrections based on the intraoperative IVUS measurements did not result in a high incidence of endoleaks at fixation zones. In our opinion, the possibility of making final corrections in the choice of diameter or length of the stent graft is the additional value of intraoperative IVUS.

Utility and reliability of endovascular aortouniiliac with femorofemoral crossover graft for aortoiliac aneurysmal disease

OBJECTIVE

The purpose of this study was to determine the early efficacy of endovascular aortouniiliac stent grafts with femorofemoral bypass graft in the treatment of aortoiliac aneurysmal disease.

METHODS

We analyzed 51 consecutive patients from January 1997 to March 1999 with a mean follow-up of 15.8 months. Patients ranged in age from 44 to 93 years (mean, 75 years) with a mean aortic aneurysm diameter of 6.2 cm. Technical success was achieved in 50 patients; one patient required conversion to open repair intraoperatively. We placed 28 custom-made and 22 commercial devices. The mean operative time was 223 minutes. The endograft was extended to the external iliac artery in 42% of cases. The contralateral common iliac artery was occluded using either a closed covered stent or intraluminal coils.

RESULTS

The median hospital stay was 4 days with an average intensive care unit stay of 0.25 days. There were no operative mortalities. Two patients died during follow-up from unrelated conditions. Endoleaks occurred in 11 patients (22%); seven patients (14%) required intervention (four catheter based, three operative). Other complications occurred in 38% of patients but were largely remote or wound related. One femorofemoral bypass graft occluded immediately postoperatively as a result of an intraprocedural external iliac dissection yielding a 98% primary patency and 100% secondary patency. Clinical success was achieved in 88% of patients.

CONCLUSIONS

These data suggest that this strategy represents a reliable method of repair of aortoiliac aneurysmal disease and extends the capability of an endoluminal approach to patients with complex iliac anatomy.

Aortic stent-grafting with transrenal fixation: use of newly designed spiral Z-stent endograft

PURPOSE

To evaluate the feasibility and efficacy of a newly designed stent-graft placed across the renal arteries for exclusion of abdominal aortic aneurysms (AAAs) with short or tortuous proximal necks.

METHODS

Among a group of AAA patients treated with endovascular grafting, 5 had tortuous proximal necks and 13 had necks <20 mm (mean 13 mm). In these 18 cases, a 2- to 3-cm uncovered segment of the stent-graft was placed transrenally using a catheter inserted into the renal artery as a guide for graft margin positioning. A newly designed stent-graft was constructed from a custom-made spiral Z-stent covered with a thin-walled Dacron material; the endografts were deployed through 16-F (aortoaortic model) or 18-F sheaths (bifurcated devices). Renal function was assessed by preoperative and postoperative measurement of urea nitrogen and creatinine. Aneurysm exclusion and renal artery patency were evaluated during follow-up using spiral computed tomography and angiography.

RESULTS

The stent-grafts were correctly placed at the intended site in all 18 patients. Renal function was not affected except transiently in 1 patient who developed bilateral renal artery stenoses 24 hours after the procedure; Palmaz stents were deployed in each renal artery to reestablish satisfactory blood flow. Of the 33 renal arteries crossed by the bare stent-graft segment, all were patent over a mean 14-month follow-up (range 7-24), including the patient with Palmaz stents implanted for postprocedural renal stenosis. Complete aneurysm exclusion was maintained in 15 (83%) of 18 patients; proximal leaks persisted in 3 patients, including 2 with severely angled proximal necks.

CONCLUSIONS

Transrenal placement of the uncovered leading edge of custom-made spiral Z-stent-based endografts appears feasible and clinically effective in the treatment of AAAs with short or tortuous proximal necks.

Endograft planning without preoperative arteriography: a clinical feasibility study

PURPOSE

To investigate an alternative method of preprocedural planning for aortic endografting based solely on spiral computed tomography (CT) with 3-dimensional (3D) reconstruction without preoperative arteriography.

METHODS

From August 1997 to April 1998, 25 consecutive patients with abdominal aortic aneurysms (AAA) were evaluated for endovascular repair by spiral CT scans (2-mm slice thickness) and computerized 3D model construction. No additional imaging for planning was performed. The aortoiliac dimensions, thrombus load, calcification, and vessel tortuosity were measured and evaluated from the 3D model of the aortoiliac segment. These data were used for selecting the patients; the configuration, diameter, and length of the endograft; and the attachment sites for deployment.

RESULTS

Primary procedural success was 92% (23/25). All endografts were deployed as planned, and there were no conversions to open repair. Six patients required adjunctive procedures for delivery system access or for iliac aneurysm exclusion, as predicted by the 3D model. Mean procedural time was 91 minutes (range 24 to 273). Two (8%) type II (side branch) endoleaks both sealed spontaneously within 1 month. No graft-related complications or death occurred, for a 30-day technical success rate of 100%.

CONCLUSIONS

This computerized 3D model provided accurate data for preoperative evaluation of the aortoiliac segment for endovascular AAA repair. Satisfactory technical outcomes for aortic endografts can be achieved without the use of preprocedural invasive imaging.