Follow-up Of Abdominal Aortic Aneurysms Research Articles

Changes in Aortic Diameter and Wall Strain in Progressing Abdominal Aortic Aneurysms.

The analysis of wall strain opens new perspectives in the prediction of abdominal aortic aneurysm (AAA) rupture. This study investigates the capability of four-dimensional ultrasound (4D US) to detect and characterize changes in wall strain in the same patients during follow-up observations. Eighteen patients were examined by 64 4D US scans during a median follow-up period of 24.5 months. After performing the 4D US and manual aneurysm segmentation, kinematic analysis was performed using a customized interface and evaluation of the mean and peak circumferential strain, as well as spatial heterogeneity. All aneurysms showed a continuous diameter growth with a mean rate of 4% per year (P < .001). The mean circumferential strain (MCS) tends to increase from a median 0.89% by 10.49% per year in follow-up independent of the aneurysm diameter (P=.063). The subgroup analysis reveals a cohort with increasing MCS and decreasing spatial heterogeneity, as well as a cohort with nonincreasing MCS and increasing spatial heterogeneity (P < .05). The 4D US is able to register the strain changes in AAA follow-up. The MCS tends to increase during the observation time in the entire cohort, but the changes were independent of the maximum aneurysm diameter. The kinematic parameters allow the entire AAA cohort to differentiate into two subgroups and provide additional information about the pathologic behavior of the aneurysm wall.

Endovascular and Open Repair of Abdominal Aortic Aneurysm.

This review presents the surgical indications, surgical procedures, and results in the treatment of asymptomatic and ruptured abdominal aortic aneurysms (AAA). An updated search of the literature on screening, diagnosis, treatment, and follow-up of AAA, based on the German clinical practice guideline published in 2018. Surgery is indicated in men with an asymptomatic AAA ≥ 5.5 cm and in women, ≥ 5.0 cm. The indication in men is based on four randomized trials, while in women the data are not conclusive. The majority of patients with AAA (around 80%) meanwhile receive endovascular treatment (endovascular aortic repair, EVAR). Open surgery (open aneurysm repair, OAR) is reserved for patients with longer life expectancy and lower morbidity. The pooled 30-day mortality is 1.16% (95% confidence interval [0.92; 1.39]) following EVAR, 3.27% [2.7; 3.83] after OAR. Women have higher operative/interventional mortality than men (odds ratio 1.67%). The mortality for ruptured AAA is extremely high: around 80% of women and 70% of men die after AAA rupture. Ruptured AAA should, if possible, be treated via the endovascular approach, ideally with the patient under local anesthesia. Treatment at specialized centers guarantees the required expertise and infrastructure. Long-term periodic monitoring by mean of imaging (duplex sonography, plus computed tomography if needed) is essential, particularly following EVAR, to detect and (if appropriate) treat endoleaks, to document stable diameter of the eliminated aneurysmal sac, and to determine whether reintervention is necessary (long-term reintervention rate circa 18%). Vascular surgery now offers a high degree of safety in the treatment of patients with asymptomatic AAA. Endovascular intervention is preferred.

General principles and overview of vascular contrast-enhanced ultrasonography.

Ultrasonography (US) is the first-line modality for the evaluation of vascular pathology. Although well-established for many diseases, US has inherent limitations that can occasionally hinder an accurate diagnosis. The value of US was improved by the introduction of microbubbles as ultrasonographic contrast agents (UCAs) and the emergence of contrast-enhanced ultrasonography (CEUS), following the introduction of second-generation UCAs and the emergence of modern contrast-specific techniques. CEUS offers valuable information about vascular disease, both on a macrovascular and a microvascular level, with well-established applications for carotid disease, post-interventional follow-up of abdominal aortic aneurysms, and the assessment of portal vein thrombosis. The purpose of this review is to discuss the principles of CEUS and to present an overview of its vascular applications.

Short version of the S3 guideline on screening, diagnosis, therapy and follow-up of abdominal aortic aneurysms

In this article a brief version of the newly developed S3 guidelines on screening, diagnosis, therapy and follow-up of abdominal aortic aneurysms (AAA), which was developed under the auspices of the German Society of Vascular Surgery and VascularMedicine (DGG) is presented. In addition to the DGG, participating professional societies were the German Radiological Society (DRG), German Society for Angiology/Society for Vascular Medicine (DGA), German Interdisciplinary Association for Intensive Care and Emergency Medicine (DIVI), German Society for Ultrasound in Medicine (DEGUM), German Vascular League e.V., German Society for Interventional Radiology (DEGIR), German Society for Anesthesiology and Intensive Care Medicine (DGAI), German Society for Thoracic and Cardiovascular Surgery (DGTHG) and the German Society of Surgery (DGCH). The guidelines are based on a systematic literature search in Medline (PubMed) for the period from 1 January 2000 to 1 January 2017. Important publications from 2017 were also considered. The selection of evidence was made by a multilevel screening process. In addition to the evidence, other criteria were included in the assessment of the recommendation level, such as the consistency of the study results, the clinical relevance of the endpoints and effect sizes, the benefit–risk balance, the applicability of the study results to the patient target group and the care system, the feasibility of the recommendations in everyday life, patient preferences and ethical and legal considerations. All recommendations/findings were approved with strong consensus (approval of >95% of the participating professional societies/associations). Thus, the present text version of the S3 guidelines on AAA represents the view of all participating societies.

Fully automatic detection and segmentation of abdominal aortic thrombus in post-operative CTA images using Deep Convolutional Neural Networks

Computerized Tomography Angiography (CTA) based follow-up of Abdominal Aortic Aneurysms (AAA) treated with Endovascular Aneurysm Repair (EVAR) is essential to evaluate the progress of the patient and detect complications. In this context, accurate quantification of post-operative thrombus volume is required. However, a proper evaluation is hindered by the lack of automatic, robust and reproducible thrombus segmentation algorithms. We propose a new fully automatic approach based on Deep Convolutional Neural Networks (DCNN) for robust and reproducible thrombus region of interest detection and subsequent fine thrombus segmentation. The DetecNet detection network is adapted to perform region of interest extraction from a complete CTA and a new segmentation network architecture, based on Fully Convolutional Networks and a Holistically-Nested Edge Detection Network, is presented. These networks are trained, validated and tested in 13 post-operative CTA volumes of different patients using a 4-fold cross-validation approach to provide more robustness to the results. Our pipeline achieves a Dice score of more than 82% for post-operative thrombus segmentation and provides a mean relative volume difference between ground truth and automatic segmentation that lays within the experienced human observer variance without the need of human intervention in most common cases.

Patients' perceptions of conservative treatment for a small abdominal aortic aneurysm.

BackgroundAn abdominal aortic aneurysm (AAA) is a progressive, generally symptomless disease that could ultimately result in a fatal rupture. Current guidelines advise conservative follow-up, and preventive surgical repair once the risk of rupture outweighs the cost of repair (55 mm in men). In developed countries, the majority of patients are diagnosed with AAAs less than 55 mm, and so enter a period of conservative surveillance. An important question is how patients perceive and cope with risk of rupture, AAA diagnosis and treatment, and presented AAA information. The goal of this study was to gain insight into patients’ perceptions of conservative treatment for a small AAA to increase patient satisfaction.MethodsWe conducted semistructured in-depth interviews and used questionnaires measuring health-related quality of life (RAND 36-Item Health Survey 1.0), illness-perceptions (Illness Perception Questionnaire – Revised), and anxiety and depression (Hospital Anxiety and Depression Scale). Interviews were audio recorded and transcript contents were analyzed based on grounded theory. Mean scores of the questionnaires were compared to (population) reference groups.ResultsThis study included ten male patients under surveillance for a small AAA from two hospitals in the Netherlands. Patients expressed no fear for AAA rupture, and also reported low levels of anxiety and depression in both the interviews and the Hospital Anxiety and Depression Scale. The presence of an AAA did not affect their social life or emotional well-being. The reported poorer physical health on RAND 36-Item Health Survey 1.0 presumably reflected common presence of comorbidities. Participants stated to that they were content with the frequency and setup of AAA surveillance. However, they generally lacked knowledge about AAA disease and/or treatment options.ConclusionConservative AAA follow-up ensures patients that the risks of AAA disease are limited. The vascular surgeon is the most important source of AAA information to patients, and patients fully rely on their vascular surgeon to take control in AAA treatment.

Transauricular intra-arterial and intravenous digital subtraction angiography for abdominal aortic aneurysm imaging in a rabbit model.

AimThe aim of this study was to evaluate transauricular digital subtraction angiography (DSA) as an alternative to conventional intra-arterial DSA for rabbit abdominal aortic aneurysm (AAA).Materials and methodsAAA models were created in 8 New Zealand white rabbits by sewing vein patch. The diameters of aortic arteries were measured by DSA via ear vein and ear central artery. The common carotid artery (CCA) was exposed and cannulated for DSA as conventional angiography. Diameter size was measured and compared.ResultsAortic diameters, tested by DSA via ear vein, ear central artery and CCA were 7.9 ± 1.2 mm, 7.8 ± 1.0 mm and 7.9 ± 1.1 mm respectively, with no significant differences. Angiography via CCA as standard procedure, correlation in aneurysm neck diameter was r = 0.93 for IVDSA and r = 0.96 for angiography via central artery (P < 0.01); Correlation in AAA diameter was r = 0.99 for IVDSA and r = 0.99 for angiography via central artery (P < 0.0001).ConclusionsTransauricular DSA shows good correlation to conventional DSA, can be used repeatedly with less invasiveness, and suitable for rabbit AAA follow-up study.

Commentary on: “Could Four Dimensional Contrast-enhanced Ultrasounds Replace Computed Tomography Angiography During Follow-up of Fenestrated Endografts? Results of a Preliminary Experience”

Fenestrated endovascular aneurysm repair (fEVAR) is a wellestablished alternative to open repair for patients with juxtarenal or short-neck AAAs. While computed tomography angiography (CTA) is considered the gold standard for surveillance, it bears the risk of contrast nephropathy and exposure to ionizing radiation, and is associated with high cost and resource allocation. Recommendations for standard EVAR have progressively changed to accept Duplex ultrasound (DUS)-based strategies, at least for patients at lower risk of complications. Currently, there are no specific recommendations from scientific societies regarding fEVAR surveillance, but expert opinion suggests close surveillance is necessary to insure lasting results. Gargiulo et al. addressed the issue of surveillance after fEVAR in a retrospective study comparing CTA and fourdimensional contrast-enhanced ultrasound (4D-CEUS). The authors suggest that 4D-CEUS is as accurate as CTA for detecting diameter and volume changes, endoleaks, and revascularized visceral vessel patency.While the conclusions are interesting, these data must be analyzed with caution. In fact, endoleak detection may be sub-optimal, as one in three endoleaks were not detected with CEUS. A sample of 22 patients is clearly underpowered to obtain conclusions that may influence clinical practice. It may be possible that, due to the relative rarity of fEVAR, one may never obtain enough power for robust conclusions. Also, the added value of 4D (compared to “standard” CEUS) appears only pertinent for volumetric measurements. While this is a valuable research tool, it is not regularly used in clinical practice and may have very limited influence on the course of treatment. As such, the present study does not add significantly to the larger study by Perini et al., where CEUS was compared favorably to CTA. Lastly, DUS and CEUS have important limitations that limit its applicability. These are largely related to access to

State-of-the-art aortic imaging: Part II - applications in transcatheter aortic valve replacement and endovascular aortic aneurysm repair

Transcatheter aortic valve replacement (TAVR) as well as thoracic and abdominal endovascular aortic repair (TEVAR and EVAR) rely on accurate pre- and postprocedural imaging. This review article discusses the application of imaging, including preprocedural assessment and measurements as well as postprocedural imaging of complications. Furthermore, the exciting perspective of computational fluid dynamics (CFD) based on cross-sectional imaging is presented. TAVR is a minimally invasive alternative for treatment of aortic valve stenosis in patients with high age and multiple comorbidities who cannot undergo traditional open surgical repair. Given the lack of direct visualization during the procedure, pre- and peri-procedural imaging forms an essential part of the intervention. Computed tomography angiography (CTA) is the imaging modality of choice for preprocedural planning. Routine postprocedural follow-up is performed by echocardiography to confirm treatment success and detect complications. EVAR and TEVAR are minimally invasive alternatives to open surgical repair of aortic pathologies. CTA constitutes the preferred imaging modality for both preoperative planning and postoperative follow-up including detection of endoleaks. Magnetic resonance imaging is an excellent alternative to CT for postoperative follow-up, and is especially beneficial for younger patients given the lack of radiation. Ultrasound is applied in screening and postoperative follow-up of abdominal aortic aneurysms, but cross-sectional imaging is required once abnormalities are detected. Contrast-enhanced ultrasound may be as sensitive as CTA in detecting endoleaks.

Remodeling of proximal neck angulation after endovascular aneurysm repair

This study investigated the remodeling of proximal neck (PN) angulations of abdominal aortic aneurysms (AAAs) after endovascular aneurysm repair (EVAR). A 64-row multidetector computed tomography scan of AAAs treated with EVAR was reviewed, and the PN angulation was measured on a volume-rendered three-dimensional image. The computed tomography scan was examined preoperatively, after EVAR at 1 week, 1 month, 6 months, 1 year, 1.5 years, 2 years, and then yearly. The study enrolled 78 patients, comprising 54 Zenith devices (Cook Medical, Bloomington, Ind) and 24 Excluder devices (W. L. Gore and Associates, Flagstaff, Ariz). PN angulation was 50° ± 20° preoperatively, and after EVAR was 36° ± 14° at 1 week, 32° ± 14° at 1 year, and 28° ± 13° at 3 years. PN angulations ≤ 60° (n = 70, 77%) were 41° ± 13° preoperatively, 31° ± 12° 1 week after EVAR, 28° ± 12° at 1 year, and 26° ± 13° after 3 years. An angulation >60° (n = 18, 23%) was 78° ± 14° preoperatively, 51° ± 11° 1 week after EVAR, 44° ± 11° at 1 year, and 40° ± 12° after 3 years. The greater the preoperative PN angulation, the greater its reduction immediately after EVAR (r = .72, P < .001). The diameter shrinkage of AAAs with a PN angulation >60° was 3 ± 6 mm after 1 year; a significantly smaller shrinkage than with a PN angulation ≤ 60° (7 ± 7 mm, P < .05). AAAs with a PN angulation >60° had a larger angulation reduction and a smaller diameter shrinkage after the EVAR procedure. The PN angulation of the 54 AAAs treated by Zenith was 49° ± 22° preoperatively, 34° ± 14° 1 week after EVAR, and 25° ± 13° after 3 years. The corresponding angulation of the 24 AAAs treated by Excluder devices was 52° ± 17°, 41° ± 14°, and 38° ± 9°, respectively. The PN angulation reduction of Zenith and Excluder was similar 1 week after the EVAR procedure. Unlike Excluder, however, the PN angulation in Zenith continued to reduce for a long period at a slow pace. There were no significant correlations between PN angulation reduction and diameter change and between PN length and diameter change (P = .86 and .18, respectively). Although the instructions for use of most commercially available stent grafts provide for a PN angulation of ≤ 60°, PN angulation was not a major issue in a midterm follow-up of AAAs with adequate PN length for patients in this series who received a Zenith or Excluder graft.

Volumetric analysis of the aneurysmal sac with computed tomography in the follow-up of abdominal aortic aneurysms after endovascular treatment

Our aim was to assess the usefulness of volumetric analysis for the follow-up of abdominal aortic aneurysms after endovascular repair (EVAR) and operator independence of the method. We retrospectively evaluated 99 computed tomography (CT) exams of 33 patients. Two blinded operators assessed the volume before treatment and after EVAR at 1-3 and 12-24 months. Friedman's statistical test was used to assess the reproducibility of the method. The time required for postprocessing by the two operators was compared. One patient was excluded. Twenty-one patients showed no endoleak: 12/21 showed a volume reduction at both follow-up scans (9.7% and 19.5%, respectively); 8/21 showed an early volume increase (9.8%) with a late reduction (10.5%); 1/21 patient showed a volume increase at both follow-up scans (endotension). Eleven patients had an endoleak (one type I, nine type II and one type III); 4/9 type II endoleaks showed a volume reduction at both post-EVAR scans (8.5% and 19.5%). All other cases showed a volume increase after EVAR (type II 15.4%/16.8%, type I 24.1%/9.1%, type III 8%/10.7%). The Friedman statistical test assessed operator independence with p < 0.001. Mean difference between the two operators was 0.9% (0-4.3%). CT volume analysis is an accurate and reproducible modality for the follow-up of abdominal aortic aneurysms after EVAR. At early follow-up, contrast-enhanced CT remains mandatory to identify small endoleaks. For later follow-up, volumetric analysis would eliminate the need for contrast material in asymptomatic patients with stable or decreasing aneurysm volume.

Follow-up of abdominal aortic aneurysm after endovascular aortic repair: Comparison of volumetric and diametric measurement

To determine the correlation of maximal diameter measurements with volumetric evaluation of size after endovascular aortic repair (EVAR) of abdominal aortic aneurysms (AAA) using computed tomography angiography (CTA) and to survey its applicability for clinical follow-up. 73 consecutive patients (2 females, 71 males; age 38-84 years; mean age, 69.1 ± 8 years) with AAA were treated with percutaneous EVAR in a single institution. For follow-up, CTA was performed periodically after EVAR. Images were evaluated for maximal diameter in consensus by two experienced radiologists. Using OsirixTM, volumetric measurements were done by one radiologist, including the entire infrarenal abdominal aorta. In 73 patients 220 CTA examinations were performed after EVAR with a mean follow-up of 17.3 months (range, 1.8-42.7 months). The mean postinterventional volume of aneurysm was 165.63 ml ± 93.29 ml (range, 47.94-565.67 ml). The mean maximal postinterventional diameter was 5.91 ± 1.52 cm (range, 3.72-13.82 cm). At large over the entire observation period a slight, non-significant decrease of 1.6% (2.58ml ± 69.05 ml, range 82.82-201.92 ml) in volumes and a 9.3% (mean 0.55 cm ± 1.22 cm, range 2.85-1.93cm) in diameters were observed. For all examinations a high correlation of volume and diameter was calculated (r = 0.813-0.905; α<0.01). For follow-up of abdominal EVAR using CTA there is a high correlation between volumetric and diametric measurements of aneurysm. Based on a daily clinical routine setting, measurements of maximal diameters in cross sectional imaging of AAA after EVAR seems to be sufficient to exclude post interventional enlargement.

ENDOCOM: Implantable wireless pressure sensor for the follow-up of abdominal aortic aneurysm stented

An abdominal aortic aneurysm (AAA) is a dilatation of the aorta at the abdominal level, the rupture of which is a life threatening complication with an 80% mortality rate. Even though those devices keep improving, the failure rate of the endovascular treatment is due to persisting pressure into the excluded aneurysmal sac. Since 2005, several integrated sensors have been designed for the follow-up of the AAA treated by a stent. Solutions are based on the use of a single sensor. Thrombus in the excluded AAA can modify the field of pressure when leaks appeared and a network of sensors should be used. We present in this paper the ENDOCOM project that aims to design an implantable pressure sensor that can be used in a network configuration. To validate the new materials, we developed a framework composed of in vitro experiments and in vivo tests on large animal model. Numerical modeling has been investigated from the experimental data to determine the optimal position of sensor. Some results of those different parts are shown in this paper.

Early Abdominal Aortic Endografts: A Decade Follow-up Results

Objectives To report the results of long-term follow-up of abdominal aortic aneurysms (AAAs) treated with endografts more than a decade ago. Design Retrospective analysis of estimated long-term follow-up, mortality and morbidity in terms of complications and re-interventions, using the Kaplan–Meier survival analysis. Materials/methods Between March 1997 and January 2000, 61 patients with AAA (53 asymptomatic, four symptomatic and three ruptured) were treated with aortic endografts. All preoperative, operative and follow-up data were recorded according to the EUROpean collaborators on Stent graft Techniques for abdominal aortic Aneurysm (EUROSTAR) criteria. Results The primary technical success rate was 98.4%. The majority of used devices were Vanguard (65.0%), and in a bifurcated configuration (86.7%). At 10-year follow-up, the estimated cumulative follow-up rate was 82.0%; complications occurred in 74.6% of the patients and re-interventions were required in 56.9%. The Vanguard endograft was related to a higher incidence of re-interventions ( P = 0.012). The combined in-hospital or AAA-related mortality rate was 5.0% at 30 days and 8.2% at a 10-year follow-up (1.8% and 5.0% in elective cases, respectively). Conclusions Early abdominal endografts are associated with high incidence of complications (74.6%) and re-interventions (56.9%) at a 10-year follow-up; however, the mortality rate related to the procedure or aneurysm is low (5.0% in elective cases). Early endografts need lifelong strict surveillance.

Clinical validation of a software for quantitative follow-up of abdominal aortic aneurysm maximal diameter and growth by CT angiography

Purpose To compare the reproducibility and accuracy of abdominal aortic aneurysm (AAA) maximal diameter (D-max) measurements using segmentation software, with manual measurement on double-oblique MPR as a reference standard. Materials and methods The local Ethics Committee approved this study and waived informed consent. Forty patients (33 men, 7 women; mean age, 72 years, range, 49–86 years) had previously undergone two CT angiography (CTA) studies within 16 ± 8 months for follow-up of AAA ≥35 mm without previous treatment. The 80 studies were segmented twice using the software to calculate reproducibility of automatic D-max calculation on 3D models. Three radiologists reviewed the 80 studies and manually measured D-max on double-oblique MPR projections. Intra-observer and inter-observer reproducibility were calculated by intraclass correlation coefficient (ICC). Systematic errors were evaluated by linear regression and Bland–Altman analyses. Differences in D-max growth were analyzed with a paired Student's t-test. Results The ICC for intra-observer reproducibility of D-max measurement was 0.992 (≥0.987) for the software and 0.985 (≥0.974) and 0.969 (≥0.948) for two radiologists. Inter-observer reproducibility was 0.979 (0.954–0.984) for the three radiologists. Mean absolute difference between semi-automated and manual D-max measurements was estimated at 1.1 ± 0.9 mm and never exceeded 5 mm. Conclusion Semi-automated software measurement of AAA D-max is reproducible, accurate, and requires minimal operator intervention.

Abdominal aortic aneurysms, screening and the law

The nature and the natural history of abdominal aortic aneurysms (AAAs) are discussed, together with current treatment options. The place of population screening for AAA is considered, particularly in the light of the Government's recent announcement of a national screening programme. Likely sources of patient complaints concerning the diagnosis, surveillance, treatment and follow-up of AAAs are discussed.

A Comparative Study of Ultrasound and Computed Tomography Scan for the follow-up of Abdominal Aortic Aneurysms after Endovascular Repair

Objective To date, computed tomography (CT) scanning has been the gold standard for follow-up of abdominal aortic aneurysms (AAA) after endovascular repair (EVR). However, with increasing durability of the minimally invasive procedure and longer survival of patients, there is concern over the expense of CT and its associated risks. For this reason, many now believe that ultrasound (US) may be an adequate substitute for surveillance of patients after EVR. The aim of this study was to compare ultrasound and CT scan in our practice to ascertain whether ultrasound alone would be sufficient for follow-up of AAA patients after EVR. Materials and Methods A total of 121 patients underwent EVR of AAAs during a 6-year period. All patients were followed up annually using both CT scanning and US. The parameters assessed included the presence/absence of endoleaks, as well as diameters of the aneurysm sac and neck. Results were plotted graphically to determine the change in size of aneurysms over time, and patients with endoleaks were compared with those who had no endoleaks. The sensitivity, specificity, positive, and negative predictive values for detecting endoleaks was also calculated for US and CT. Normally distributed data were analyzed using the Student's t-test and the Wilcox-signed rank test was used for nonparametric data. Results A total of 573 (CT and US) scans were analyzed. Of these, 391 scans (91 patients) did not show endoleaks. There were 64 scans (18 patients) in which both CT and US detected endoleaks; 6 scans (6 patients) in which CT detected leaks and US did not; and 5 scans (4 patients) in which US detected leaks and CT did not. The aneurysm sac size increased over time in the endoleak group and decreased over time in the nonendoleak group, whereas neck sizes did not change in either patient group. The sensitivity, specificity, positive, and negative predictive values of US and CT scan for detecting endoleak were 92.7%, 98.5%, 91.4%, and 98.7%; and 91.4%, 98.7%, 92.7%, and 98.5% respectively. Conclusion In our practice, US was comparable with CT scan for the detection of endoleaks, and similar trends were seen over time with regard to changes in aneurysm neck and body sizes for both modalities. We believe that US should be the primary modality for follow-up of patients after EVR and that CT scan should be reserved for confirmation of endoleak where this is suspected.