Abdominal aortic aneurysm: Treatment options, image visualizations and follow-up procedures

Long-term results of endovascular versus open retroperitoneal repair associated with ERAS protocol for abdominal aortic aneurysms

OBJECTIVES

Although the endovascular management of infrarenal abdominal aortic aneurysms (AAAs) is widely performed, many studies have shown better long-term results with open graft repairing, mostly focusing on the classical open repair with midline access. This study aims to evaluate long-term results comparing EVAR (endovascular aneurysm repair) and surgical open repair with retroperitoneal access associated with ERAS (Enhanced Recovery After Surgery) protocol.

METHODS

A retrospective analysis of 156 patients treated for AAA between 2015 and 2018 was conducted. Clinical and demographic characteristics of the two groups were homogeneous except for age, which was significantly higher in patients belonging to the EVAR one, and for previous laparotomies. A total of 100 patients (58.7%) underwent open retroperitoneal repair (ORR group), and 56 (42.3%) underwent EVAR. A mean of 51 ± 28 months of follow-up was conducted. This study aims to evaluate long-term survival by comparing EVAR (endovascular aneurysm repair) and surgical open repair with retroperitoneal access associated with ERAS (Enhanced Recovery After Surgery) protocol. Secondary aims evaluate differences between the two techniques regarding late complications, need for re-interventions, and perioperative results.

RESULTS

Freedom from all-cause mortality, calculated with Kaplan-Meier survival curves equalizing the two population with a Covariate Propensity Score, showed significant better survival rates at 1, 3, and 5 years in ORRs then in EVARs. Late complications (>30 days) and need for late re-intervention rates were greater in the EVAR group (6 late re-interventions needed vs 0 in the ORR group).Perioperative results show longer mean length of hospital stay in patients belonging to the ORR group (5 days vs 2) and significantly higher in-hospital-complication rate.

CONCLUSIONS

The long-term comparison between EVAR and open retroperitoneal repair shows significantly better late outcomes in the ORR group. The perioperative course appears significantly better in EVARs but anyway good in ORRs when a perioperative protocol as ERAS is applied.In a selected population of young patients fit for surgery, the retroperitoneal surgical approach should be highly taken into account in the therapeutical choice.

Intravascular lithotripsy supported endovascular aneurysm repair

As the use of endovascular aneurysm repair (EVAR) increases, anatomic constraints remain a challenge. In this case report, we describe the use of intravascular lithotripsy to facilitate EVAR in a patient with a severely calcified and stenotic aortic bifurcation. Future applications of intravascular lithotripsy could help expand the use of EVAR to patients with severely stenotic vasculature and optimize outcomes in the treatment of infrarenal abdominal aortic aneurysms.

Cardiovascular computed tomography in cardiovascular disease: An overview of its applications from diagnosis to prediction

Cardiovascular computed tomography angiography (CTA) is a widely used imaging modality in the diagnosis of cardiovascular disease. Advancements in CT imaging technology have further advanced its applications from high diagnostic value to minimising radiation exposure to patients. In addition to the standard application of assessing vascular lumen changes, CTA-derived applications including 3D printed personalised models, 3D visualisations such as virtual endoscopy, virtual reality, augmented reality and mixed reality, as well as CT-derived hemodynamic flow analysis and fractional flow reserve (FFRCT) greatly enhance the diagnostic performance of CTA in cardiovascular disease. The widespread application of artificial intelligence in medicine also significantly contributes to the clinical value of CTA in cardiovascular disease. Clinical value of CTA has extended from the initial diagnosis to identification of vulnerable lesions, and prediction of disease extent, hence improving patient care and management. In this review article, as an active researcher in cardiovascular imaging for more than 20 years, I will provide an overview of cardiovascular CTA in cardiovascular disease. It is expected that this review will provide readers with an update of CTA applications, from the initial lumen assessment to recent developments utilising latest novel imaging and visualisation technologies. It will serve as a useful resource for researchers and clinicians to judiciously use the cardiovascular CT in clinical practice.

Higher matrix stiffness promotes VSMC senescence by affecting mitochondria-ER contact sites and mitochondria/ER dysfunction

Abdominal aortic aneurysm (AAA) is a prevalent condition characterized by the weakening and bulging of the abdominal aorta. This study aimed to investigate the impact of a stiff matrix on vascular smooth muscle cells (VSMCs) in AAA development. Bioinformatics analysis revealed that differentially expressed genes (DEGs) in VSMCs of an AAA mouse model were enriched in cellular senescence and related pathways. To simulate aging-related changes, VSMCs were cultured on stiff matrices, and compared to those on soft matrices, the VSMCs cultured on stiff matrices exhibited cellular senescence. Furthermore, the mutual distance between mitochondria and endoplasmic reticulum (ER) in VSMCs was increased, indicating altered mitochondria-endoplasmic reticulum contacts (MERCs). The observed upregulation of reactive oxygen species (ROS) levels, antioxidant gene expression, and decreased mitochondrial membrane potential suggested the presence of mitochondrial dysfunction in VSMCs cultured on a stiff matrix. Additionally, the induction of ER stress-related genes indicated ER dysfunction. These findings collectively indicated impaired functionality of both mitochondria and ER in VSMCs cultured on a stiff matrix. Moreover, our data revealed that high lipid levels exacerbated the effects of high matrix stiffness on VSMCs senescence, MERC sites, and mitochondria/ER dysfunction. Importantly, treatment with the antilipemic agent CI-981 effectively reversed these detrimental effects. These findings provide insights into the role of matrix stiffness, mitochondrial dysfunction, ER stress, and lipid metabolism in AAA development, suggesting potential therapeutic targets for intervention.

Decrease in Haemoglobin in Association with Aneurysm Volume Loss after Endovascular Repair of Abdominal Aortic Aneurysm

Background

Anaemia (low haemoglobin [Hb]) is well known to be associated with high mortality and adverse cardiac events following surgical treatment of abdominal aortic aneurysm (AAA). However, little is known about the relationship of AAA volume and Hb level alterations with endovascular repair of AAA. This study aimed to examine the changes in the Hb level and aneurysm volume before and after endovascular aneurysm repair (EVAR) for AAA and determine the relationship between the post-operative Hb level and the volume loss of AAA.

Methods

This retrospective study reviewed patients with AAA who underwent EVAR between January 2020 and February 2021 at a tertiary medical centre. The clinical features and medical history of the patients were analysed. Alterations in the Hb level were recorded, and the AAA volume was calculated from computed tomography angiography images before and after EVAR to infer the association between the post-operative Hb level and alterations in AAA volume. Moreover, AAA volume, pre-operative Hb level and medical history were studied to identify the risk factors for anaemia 24 h after EVAR.

Results

A total of 74 patients (mean age, 67 ± 7.9 years) were included in this study. The Hb level decreased significantly 24 h after EVAR, and the post-operative Hb level was negatively correlated with AAA volume loss (r = -0.252, p = 0.041). No relationship was observed between AAA volume loss and decrease in the Hb level (r = 0.072, p = 0.571) or between pre-operative AAA volume and decrease in the Hb level (r = 0.072, p = 0.566). Furthermore, 59.5% of the patients (n = 44) developed anaemia 24 h after EVAR. The odds ratio (OR) of anaemia 24 h after EVAR was 5.3 times higher in those with hypertension (OR, 5.304; 95% confidence interval [CI], 1.024-27.424) than in those without the condition. The pre-operative Hb level (or normal Hb level) was a protective factor (OR = 0.909; 95% CI, 0.853-0.969). The area under the receiver operating characteristic curve was 0.840. The post-operative Hb level declined significantly, and AAA volume loss contributed to it. Moreover, hypertension was identified to be a risk factor for anaemia 24 h after EVAR, and pre-operative Hb level was discerned to be a protective factor.

Conclusions

The findings suggest that decrease in the Hb level in the early post-EVAR stage warrants the attention of surgeons, especially in patients with a history of hypertension or a low pre-operative Hb level.

MetAAA trial patients show superior quality of life compared to patients under regular surveillance for small AAA: a single-center retrospective cohort study

BACKGROUND

Abdominal aortic aneurysm (AAA) is a multifactorial vascular disease associated with high morbidity and mortality. Currently, surgical intervention is the only treatment option, and there is no drug therapy available for AAA. Hence, surveillance of AAA until indication for surgery may impact patient quality of life (QoL). There is a paucity of high-quality observational data on health status and QoL, particularly among AAA patients participating in randomized controlled trials. The objective of this study was to compare the QoL scores of AAA patients on surveillance to those of AAA patients enrolled in the MetAAA trial.

MATERIAL AND METHODS

Overall, 54 MetAAA trial patients and 23 AAA patients under regular surveillance for small AAA (part of a longitudinal monitoring study) were asked to complete three established and validated (in total 561 longitudinally collected) QoL questionnaires: the 36-Item Short Form Health Survey (SF-36), the Aneurysm Symptom Rating Questionnaire (ASRQ), and the Aneurysm-Dependent Quality of Life questionnaire (ADQoL).

RESULTS

A superior health status and QoL was found in AAA patients participating in the MetAAA trial compared to AAA patients under regular surveillance. In detail, MetAAA trial patients showed superior general health perception ( P =0.012), higher energy level ( P =0.036) as well as enhanced emotional well-being ( P =0.044) and fewer limitations due to general malaise ( P =0.021), which was subsequently reflected in an overall superior current QoL score ( P =0.039) compared to AAA patients under regular surveillance.

CONCLUSION

AAA patients enrolled in the MetAAA trial showed superior health status and QoL compared to AAA patients under regular surveillance.

Carotid artery vasoreactivity correlates with abdominal aortic vasoreactivity in young healthy individuals but not in patients with abdominal aortic aneurysm

Background

Sympathetic stimulation of central arteries, such as coronary and carotid arteries, cause vasodilation in healthy subjects, but vasoconstriction in those with increased cardiovascular risk. This study compared vasoreactivity to sympathetic stimulation between abdominal aorta and carotid artery in healthy young individuals (young group, n = 20), in patients with abdominal aortic aneurysm (AAA group, n = 20) and in a healthy older group, age- and gender matched with AAA group (matched group, n = 18).

Method

All subjects underwent cold pressor test, while performing concomitantly duplex ultrasound of abdominal aorta and carotid artery vasoreactivity. Observer-independent software was used to analyze and calculate magnitude and timing of maximum vasodilation or vasoconstriction. Pearson's correlation coefficient was calculated to investigate vasoreactivity between arteries.

Results

Carotid artery reactivity [Interquartile range 25%, Interquartile range 75%] did not significantly differ between the young, matched and AAA group (3.5% [1.4, 4.7], 2.6% [2.0, 4.1] and 2.2% [-1.9, 3.7], respectively, p = 0.301). Abdominal aortic responsiveness demonstrated larger differences between young (4.9% [-0.2, 8.4]), matched (3.3% [-2.5, 4.4]) and individuals with AAA (0.5% [-3.9, 4.1], p = 0.059). Pooled analysis showed a significant correlation between carotid and abdominal aortic vasoreactivity (r = 0.444, p = 0.001). Subgroup analyses demonstrated significant correlation between both arteries in young (r = 0.636, p = 0.003), but not matched (r = −0.040, p = 0.866) or AAA group (r = 0.410, p = 0.129).

Conclusions

Sympathetic stimulation induces powerful vasodilation of the carotid artery and abdominal aorta, which is significantly correlated in healthy individuals. No such correlation is present in abdominal aortic aneurysm patients. This suggests the aneurysm alters local abdominal aorta vasoreactivity, but not the carotid artery.

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Vasoreactivity is significantly correlated between carotid and abdominal aorta.

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Presence of abdominal aneurysm was associated with local impaired vasoreactivity.

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Abdominal aorta demonstrates a stronger vasoreactivity than the carotid artery.

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Vasoreactivity of the carotid artery did not differ between groups.

Efficient parallel simulation of hemodynamics in patient-specific abdominal aorta with aneurysm

Surgical planning for aortic aneurysm repair is a difficult task. In addition to the morphological features obtained from medical imaging, alternative features obtained with computational modeling may provide additional useful information. Though numerical studies are noninvasive, they are often time-consuming, especially when we need to study and compare multiple repair scenarios, because of the high computational complexity. In this paper, we present a highly parallel algorithm for the numerical simulation of unsteady blood flows in the patient-specific abdominal aorta before and after the aneurysmic repair. We model the blood flow with the unsteady incompressible Navier-Stokes equations with different outlet boundary conditions, and solve the discretized system with a highly scalable domain decomposition method. With this approach, a high resolution simulation of a full-size adult aorta can be obtained in less than an hour, instead of days with older methods and software. In addition, we show that the parallel efficiency of the proposed method is near 70% on a parallel computer with 2, 880 processor cores.

Evolving Utility of Endovascular Treatment of Juxtarenal, Pararenal, and Suprarenal Abdominal Aortic Aneurysms Associated With Increased Risk of Mortality Over Time

BACKGROUND

Continued advances in endovascular technologies are resulting in fewer open abdominal aortic aneurysm (AAA) repairs. In addition, more complex juxtarenal, pararenal, and suprarenal (JPS) AAAs are being managed with various endovascular techniques. This study sought to evaluate the evolving trends in endovascular aneurysm repair (EVAR) of AAAs, hypothesizing increased rate of JPS AAA repair by EVAR. We also sought to evaluate the risk for morbidity and mortality for EVAR and open aneurysm repair (OAR) of JPS AAAs over time.

METHODS

The 2011-2017 American College of Surgeons National Surgical Quality Improvement Program Procedure-Targeted Vascular database was queried for patients undergoing OAR or EVAR for AAAs. A multivariable logistic regression analysis was performed for both infrarenal and JPS AAA repairs.

RESULTS

Of 18,661 patients who underwent AAA repair, 3,941 (21.1%) were OAR and 14,720 (78.9%) were EVAR. The rate of OAR decreased from 29.5% in 2011 to 21.3% in 2017 (P < 0.001) with a geometric-mean-annual decrease of 27.8%. The rate of EVAR increased from 70.5% to 78.7% during the same time period (P < 0.001) with a geometric-mean-annual increase of 11.6%. These trends remained true for both infrarenal and JPS AAAs. After adjusting for covariates, there was no difference in associated risk of 30-day mortality, renal complications, or ischemic colitis for either OAR or EVAR over each incremental year for infrarenal AAAs (P > 0.05). However, in patients undergoing EVAR for JPS AAAs, the associated risk of mortality increased with each incremental year (odds ratio [OR]: 1.30, confidence interval [CI]: 1.01-1.69, P = 0.039), whereas there was no difference in the risk of mortality for OAR of JPS AAAs with each incremental year (OR: 1.11, CI: 0.99-1.23, P = 0.067).

CONCLUSIONS

The rate of OAR for AAA has decreased over the past seven years with an increase in EVAR, particularly for more complex JPS AAAs. The associated risk for morbidity and mortality for treatment of infrarenal AAAs was not significantly affected by this increased utility of EVAR. The associated risk of mortality for JPS AAAs treated by EVAR increased over time, whereas this trend for associated risk of mortality was not seen for OAR of JPS AAAs. These findings, especially the increased associated risk of mortality over time with EVAR for JPS AAAs, warrant careful prospective analysis.

Image-Based 3D Characterization of Abdominal Aortic Aneurysm Deformation After Endovascular Aneurysm Repair

An abdominal aortic aneurysm (AAA) is a focal dilation of the abdominal aorta, that if not treated, tends to grow and may rupture. The most common treatment for AAAs is the endovascular aneurysm repair (EVAR), which requires that patients undergo Computed Tomography Angiography (CTA)-based post-operative lifelong surveillance due to the possible appearance of complications. These complications may again lead to AAA dilation and rupture. However, there is a lack of advanced quantitative image-analysis tools to support the clinicians in the follow-up. Currently, the approach is to evaluate AAA diameter changes along time to infer the progress of the patient and the post-operative risk of AAA rupture. An increased AAA diameter is usually associated with a higher rupture risk, but there are some small AAAs that rupture, whereas other larger aneurysms remain stable. This means that the diameter-based rupture risk assessment is not suitable for all the cases, and there is increasing evidence that the biomechanical behavior of the AAA may provide additional valuable information regarding the progression of the disease and the risk of rupture. Hence, we propose a promising methodology for post-operative CTA time-series registration and subsequent aneurysm biomechanical strain analysis. From these strains, quantitative image-based descriptors are extracted using a principal component analysis of the tensile and compressive strain fields. Evaluated on 22 patients, our approach yields a mean area under the curve of 88.6% when correlating the strain-based quantitative descriptors with the long-term patient prognosis. This suggests that the strain information directly extracted from the CTA images is able to capture the biomechanical behavior of the aneurysm without relying on finite element modeling and simulation. Furthermore, the extracted descriptors set the basis for possible future imaging biomarkers that may be used in clinical practice. Apart from the diameter, these biomarkers may be used to assess patient prognosis and to enable informed decision making after an EVAR intervention, especially in difficult uncertain cases.

Comparison of in vivo vs. ex situ obtained material properties of sheep common carotid artery

Patient-specific biomechanical modelling can improve preoperative surgical planning. This requires patient-specific geometry as well as patient-specific material properties as input. The latter are, however, still quite challenging to estimate in vivo. This study focuses on the estimation of the mechanical properties of the arterial wall. Firstly, in vivo pressure, diameter and thickness of the arterial wall were acquired for sheep common carotid arteries. Next, the animals were sacrificed and the tissue was stored for mechanical testing. Planar biaxial tests were performed to obtain experimental stress-stretch curves. Finally, parameters for the hyperelastic Mooney-Rivlin and Gasser-Ogden-Holzapfel (GOH) material model were estimated based on the in vivo obtained pressure-diameter data as well as on the ex situ experimental stress-stretch curves. Both material models were able to capture the in vivo behaviour of the tissue. However, in the ex situ case only the GOH model provided satisfactory results. When comparing different fitting approaches, in vivo vs. ex situ, each of them showed its own advantages and disadvantages. The in vivo approach estimates the properties of the tissue in its physiological state while the ex situ approach allows to apply different loadings to properly capture the anisotropy of the tissue. Both of them could be further enhanced by improving the estimation of the stress-free state, i.e. by adding residual circumferential stresses in vivo and by accounting for the flattening effect of the tested samples ex vivo. • Competing interests: none declared • Word count: 4716.

Ten-year single-centre experience with type II endoleaks: Intervention versus observation

Our objective was to determine the relative merits of intervention or observation of type II endoleaks (T2Ls). A retrospective analysis was performed on 386 infra-renal endovascular aneurysm repair (IR-EVAR) patients from 2006 to 2015. Annual surveillance imaging of patients undergoing EVAR at our centre were analysed, and all endoleaks were subjected to a multidisciplinary team meeting for consideration and treatment. In the 10-year time frame, 386 patients (79.5±8.7 years) underwent an IR-EVAR. Eighty-one patients (21.0%) developed a T2L and intervention was undertaken in 28 (34.6%): 17 (60.7%) were treated via a transarterial approach (TA) and 11 (39.3%) using the translumbar approach (TL). Fifty-three patients (65.4%) with T2Ls were managed conservatively. Patients who received T2L treatment had a greater proportion of recurrent T2Ls than patients who were conservatively managed ( p=0.032). T2Ls associated with aneurysmal growth were more resistant to treatment than those where there was no change or a decrease in aneurysm size during follow-up (0.033). There was no significant difference in the TA and TL approach with respect to endoleak repair success ( p=0.525). Treatment of a T2L did not confer a survival advantage compared to conservative management ( p=0.449) nor did the choice of either the TA or TL approach ( p=0.148). Our study suggests the development of a T2L associated with aneurysm growth may represent an aggressive phenotype that is resistant to treatment. However, this did not lead to an increased risk of mortality over follow-up. Neither a transarterial nor a translumbar approach to treating a T2L conferred superiority.

Acute Aortic Syndromes: Update in Current Medical Management

OPINION STATEMENT

Advances in medical therapy and non-surgical percutaneous options to manage the specter of acute aortic syndromes have improved both patient morbidity and mortality. There are key features in the patient history and initial exam which physicians should be attuned to in order to diagnose acute aortic syndromes such as aortic dissection, penetrating aortic ulcer, and intramural hematoma. Once recognized, early initiation of the appropriate pharmacologic therapy is important, and further appreciating the limitations of such therapy before considering a surgical approach is critical to improve patient outcomes. For the undifferentiated patient with acute aortic dissection presenting to facilities who do not routinely manage this condition, adding pharmacologic agents in the correct sequence assures the best chance for a satisfactory outcome.

CT angiography in the diagnosis of cardiovascular disease: a transformation in cardiovascular CT practice

Computed tomography (CT) angiography represents the most important technical development in CT imaging and it has challenged invasive angiography in the diagnostic evaluation of cardiovascular abnormalities. Over the last decades, technological evolution in CT imaging has enabled CT angiography to become a first-line imaging modality in the diagnosis of cardiovascular disease. This review provides an overview of the diagnostic applications of CT angiography (CTA) in cardiovascular disease, with a focus on selected clinical challenges in some common cardiovascular abnormalities, which include abdominal aortic aneurysm (AAA), aortic dissection, pulmonary embolism (PE) and coronary artery disease. An evidence-based review is conducted to demonstrate how CT angiography has changed our approach in the diagnosis and management of cardiovascular disease. Radiation dose reduction strategies are also discussed to show how CT angiography can be performed in a low-dose protocol in the current clinical practice.

Endovascular treatment of abdominal aortic aneurysms

Patients with abdominal aortic aneurysms (AAAs) are usually treated with endovascular aneurysm repair (EVAR), which has become the standard of care in many hospitals for patients with suitable anatomy. Clinical evidence indicates that EVAR is associated with superior perioperative outcomes and similar long-term survival compared with open repair. Since the randomized, controlled trials that provided this evidence were conducted, however, the stent graft technology for infrarenal AAA has been further developed. Improvements include profile downsizing, optimization of sealing and fixation, and the use of low porosity fabrics. In addition, imaging techniques have improved, enabling better preoperative planning, stent graft placement, and postoperative surveillance. Also in the past few years, fenestrated and branched stent grafts have increasingly been used to manage anatomically challenging aneurysms, and experiments with off-label use of stent grafts have been performed to treat patients deemed unfit or unsuitable for other treatment strategies. Overall, the indications for endovascular management of AAA are expanding to include increasingly complex and anatomically challenging aneurysms. Ongoing studies and optimization of imaging, in addition to technological refinement of stent grafts, will hopefully continue to broaden the utilization of EVAR.