Abdominal aortic aneurysm: pictorial review of common appearances and complications

Right-to-left shunt due to iatrogenic atrial septal defect manifested by aorto-caval fistula: a case report

BACKGROUND

An aorto-caval fistula is a rare but critical complication of abdominal aortic aneurysm (AAA) rupture, leading to high-output heart failure and increased venous pressure. The anesthetic management of such cases, particularly when complicated by an intraoperative right-to-left shunt, is seldom reported.

CASE PRESENTATION

A 71-year-old man with a history of atrial fibrillation and catheter ablation presented with heart failure and abdominal pain, leading to cardiac arrest. Imaging revealed an AAA rupture into the inferior vena cava. During emergency surgery, severe venous bleeding was managed using intra-aortic balloon occlusion (IABO). Transesophageal echocardiography (TEE) identified a right-to-left shunt due to an iatrogenic atrial septal defect.

CONCLUSION

Early TEE recognition and timely IABO intervention were crucial in managing this complex case, underscoring the importance of these techniques in similar emergency scenarios.

Extravertebral low back pain: a scoping review

BACKGROUND

Low back pain (LBP) is one of the most common reasons for consultation in general practice. Currently, LBP is categorised into specific and non-specific causes. However, extravertebral causes, such as abdominal aortic aneurysm or pancreatitis, are not being considered.

METHODS

A systematic literature search was performed across MEDLINE, Embase, and the Cochrane library, complemented by a handsearch. Studies conducted between 1 January 2001 and 31 December 2020, where LBP was the main symptom, were included.

RESULTS

The literature search identified 6040 studies, from which duplicates were removed, leaving 4105 studies for title and abstract screening. Subsequently, 265 publications were selected for inclusion, with an additional 197 publications identified through the handsearch. The majority of the studies were case reports and case series, predominantly originating from specialised care settings. A clear distinction between vertebral or rare causes of LBP was not always possible. A range of diseases were identified as potential extravertebral causes of LBP, encompassing gynaecological, urological, vascular, systemic, and gastrointestinal diseases. Notably, guidelines exhibited inconsistencies in addressing extravertebral causes.

DISCUSSION

Prior to this review, there has been no systematic investigation into extravertebral causes of LBP. Although these causes are rare, the absence of robust and reliable epidemiological data hinders a comprehensive understanding, as well as the lack of standardised protocols, which contributes to a lack of accurate description of indicative symptoms. While there are certain disease-specific characteristics, such as non-mechanical or cyclical LBP, and atypical accompanying symptoms like fever, abdominal pain, or leg swelling, that may suggest extravertebral causes, it is important to recognise that these features are not universally present in every patient.

CONCLUSION

The differential diagnosis of extravertebral LBP is extensive with relatively low prevalence rates dependent on the clinical setting. Clinicians should maintain a high index of suspicion for extravertebral aetiologies, especially in patients presenting with atypical accompanying symptoms.

Case report - Computed tomography diagnosis of an abdominal aortic aneurysm complicated with primary aortoduodenal fistula

Abdominal aortic aneurysm has been described as a rare condition touching 1% of the population over the age of 50 years with a high percentage of mortality. Aneurysms progress in size, causing deadly complications such as ruptures and fistulas. Computed tomography angiography is considered the gold standard imaging exam for the evaluation of abdominal aortic aneurysms and their complications. We report the case of an elderly patient admitted to the emergency room due to recurrent gastrointestinal bleeding. The computed tomography imaging findings were in favor of an abdominal aortic aneurysm complicated with a primary aortoduodenal fistula.

Microwave Imaging System Based on Signal Analysis in a Planar Environment for Detection of Abdominal Aortic Aneurysms

A proof-of-concept of a microwave imaging system for the fast detection of abdominal aortic aneurysms is shown. This experimental technology seeks to overcome the factors hampering the fast screening for these aneurysms with the usual equipment, such as high cost, long-time operation or hazardous exposure to chemical substances. The hardware system is composed of 16 twin antennas mastered by a microcontroller through a switching network, which connects the antennas to the measurement instrument for sequential measurement. The software system is run by a computer, mastering the whole system, automatizing the measurement process and running the signal processing and medical image generation algorithms. Two image generation algorithms are tested: Delay-and-Sum (DAS) and Improved Delay-and-Sum (IDAS). Own-modified versions of these algorithms adapted to the requirements of our system are proposed. The system is carefully calibrated and fine-tuned with known objects placed at known distances. An experimental proof-of-concept is shown with a human torso phantom, including an aorta phantom and an aneurysm phantom placed in different positions. The results show good imaging capabilities with the potential for detecting and locating possible abdominal aortic aneurysms and reporting acceptable errors.

The protective effects of pirfenidone in preventing abdominal aortic aneurysm formation

Vascular endothelial growth factor (VEGF)-mediated angiogenesis participates in the initiation and progression of abdominal aortic aneurysm (AAA). Pirfenidone is a compound that has anti-inflammatory and antioxidant properties and suppresses angiogenesis. Pirfenidone targets the extracellular matrix (ECM) and has therapeutic effects on fibrotic diseases. Therefore, we speculated that pirfenidone might have meaningful therapeutic effects in AAA, and the current study was designed to investigate this capacity. An AAA model was constructed in mice using a long-term injection of angiotensin II (Ang II), followed by a 28-day administration of 200 mg/kg/day pirfenidone. Increased maximal external diameter of the abdominal artery, promoted levels of VEGF-A and its receptor VEGF-R2, upregulated matrix metallopeptidases (MMP)-2 and MMP-9, and elevated release of pro-inflammatory cytokines were observed in AAA mice, which were extremely repressed by 200 mg/kg pirfenidone. Human aortic endothelial cells (HAECs) were stimulated with Ang II for 1 day, in the presence or absence of pirfenidone (100 nM). Elevated expression of VEGF-A and VEGF-R2, facilitated proliferation, increased tube formation ability, and upregulated MMP-2 and MMP-9 were observed in Ang II-stimulated HAECs, all of which were significantly rescued by 100 nM pirfenidone. Finally, the elevated levels of myeloid differentiation primary response 88 and phosphorylated nuclear factor-kappa-B subunit p65 observed in Ang II-stimulated HAECs were repressed by pirfenidone. Collectively, pirfenidone alleviated AAA by inhibiting ECM degradation and ameliorating endothelial dysfunction.

Status of diagnosis and therapy of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are characterized by localized dilation of the abdominal aorta. They are associated with several serious consequences, including compression of adjacent abdominal organs, pain, treatment-related financial expenditure. The main complication of AAA is aortic rupture, which is responsible for about 200,000 deaths per year worldwide. An increasing number of researchers are dedicating their efforts to study AAA, resulting in significant progress in this field. Despite the commendable progress made thus far, there remains a lack of established methods to effectively decelerate the dilation of aneurysms. Therefore, further studies are imperative to expand our understanding and enhance our knowledge concerning AAAs. Although numerous factors are known to be associated with the occurrence and progression of AAA, the exact pathway of development remains unclear. While asymptomatic at most times, AAA features a highly unpredictable disease course, which could culminate in the highly deadly rupture of the aneurysmal aorta. Current guidelines recommend watchful waiting and lifestyle adjustment for smaller, slow-growing aneurysms, while elective/prophylactic surgical repairs including open repair and endovascular aneurysm repair are recommended for larger aneurysms that have grown beyond certain thresholds (55 mm for males and 50 mm for females). The latter is a minimally invasive procedure and is widely believed to be suited for patients with a poor general condition. However, several concerns have recently been raised regarding the postoperative complications and possible loss of associated survival benefits on it. In this review, we aimed to highlight the current status of diagnosis and treatment of AAA by an in-depth analysis of the findings from literatures.

Focus on the Most Common Paucisymptomatic Vasculopathic Population, from Diagnosis to Secondary Prevention of Complications

Middle-aged adults can start to be affected by some arterial diseases (ADs), such as abdominal aortic or popliteal artery aneurysms, lower extremity arterial disease, internal carotid, or renal artery or subclavian artery stenosis. These vasculopathies are often asymptomatic or paucisymptomatic before manifesting themselves with dramatic complications. Therefore, early detection of ADs is fundamental to reduce the risk of major adverse cardiovascular and limb events. Furthermore, ADs carry a high correlation with silent coronary artery disease (CAD). This study focuses on the most common ADs, in the attempt to summarize some key points which should selectively drive screening. Since the human and economic possibilities to instrumentally screen wide populations is not evident, deep knowledge of semeiotics and careful anamnesis must play a central role in our daily activity as physicians. The presence of some risk factors for atherosclerosis, or an already known history of CAD, can raise the clinical suspicion of ADs after a careful clinical history and a deep physical examination. The clinical suspicion must then be confirmed by a first-level ultrasound investigation and, if so, adequate treatments can be adopted to prevent dreadful complications.

Abdominal aortic aneurysm presenting to the orthopedic clinic as posterior hip and low back pain

Abdominal aortic aneurysms (AAAs) are typically asymptomatic. When symptomatic, AAA may present as a chief concern of musculoskeletal hip and low back pain. Assessment in the orthopedic clinic should focus on a holistic examination of the patient.

Intraoperative Abdominal Aortic Aneurysm Repair and Its Complications From an Anesthesia Perspective: A Case Report

An abdominal aortic aneurysm (AAA) is a disease characterized by an abnormal bulge or swelling in the aorta. It could be serious if left unobserved, and with time, it swells and eventually ruptures, resulting in massive bleeding inside, and, more likely, causes death. This report presents a case study of a 61-year-old male who presented with back pain; no other fatal symptoms such as breathlessness or rapid heart rate were seen. His abdominal ultrasound report showed the presence of a distal aortic dissecting aneurysm, resulting in rapid diagnosis and treatment.

Abdominal Aortic Aneurysms (Etiology, Epidemiology, and Natural History)

Abdominal aortic aneurysm is a potentially lethal condition that is decreasing in frequency as tobacco use declines. The exact etiology remains unknown, but smoking and other perturbations seem to trigger an inflammatory state in the tunica media. Male sex and advanced age are clear demographic risk factors for the development of abdominal aortic aneurysms. The natural history of this disease varies, but screening remains vital as it is rarely diagnosed on physical examination, and elective repair (most commonly done endovascularly) offers significant morbidity and mortality advantages over emergent intervention for aortic rupture.

Computed tomography for aortic assessment in children

Because the aorta is the major vessel of the body, basic knowledge of aortic pathology is essential to the pediatric imager. This review divides aortic pathology into anatomical (e.g., congenital abnormalities) and acquired (e.g., vasculitis, trauma) entities, providing a brief description of pathology, technical considerations in CT acquisition and processing, and some pearls and pitfalls of interpretation. The objective of this paper is to familiarize general pediatric imagers with imaging features of common as well as high-impact aortic pathology on CT and prepare them for acquisition and reporting.

MDCT Imaging of Non-Traumatic Thoracic Aortic Emergencies and Its Impact on Diagnosis and Management—A Reappraisal

Non-traumatic thoracic aorta emergencies are associated with significant morbidity and mortality. Diseases of the intimomedial layers (aortic dissection and variants) have been grouped under the common term of acute aortic syndrome because they are life-threatening conditions clinically indistinguishable on presentation. Patients with aortic dissection may present with a wide variety of symptoms secondary to the pattern of dissection and end organ malperfusion. Other conditions may be seen in patients with acute symptoms, including ruptured and unstable thoracic aortic aneurysm, iatrogenic or infective pseudoaneurysms, aortic fistula, acute aortic thrombus/occlusive disease, and vasculitis. Imaging plays a pivotal role in the patient’s management and care. In the emergency room, chest X-ray is the initial imaging test offering a screening evaluation for alternative common differential diagnoses and a preliminary assessment of the mediastinal dimensions. State-of-the-art multidetector computed tomography angiography (CTA) provides a widely available, rapid, replicable, noninvasive diagnostic imaging with sensitivity approaching 100%. It is an impressive tool in decision-making process with a deep impact on treatment including endovascular or open surgical or conservative treatment. Radiologists must be familiar with the spectrum of these entities to help triage patients appropriately and efficiently. Understanding the imaging findings and proper measurement techniques allow the radiologist to suggest the most appropriate next management step.

AAA Revisited: A Comprehensive Review of Risk Factors, Management, and Hallmarks of Pathogenesis

Despite declining incidence and mortality rates in many countries, the abdominal aortic aneurysm (AAA) continues to represent a life-threatening cardiovascular condition with an overall prevalence of about 2-3% in the industrialized world. While the risk of AAA development is considerably higher for men of advanced age with a history of smoking, screening programs serve to detect the often asymptomatic condition and prevent aortic rupture with an associated death rate of up to 80%. This review summarizes the current knowledge on identified risk factors, the multifactorial process of pathogenesis, as well as the latest advances in medical treatment and surgical repair to provide a perspective for AAA management.

Prospect of positron emission tomography for abdominal aortic aneurysm risk stratification

Abdominal aortic aneurysm (AAA) disease is characterized by an asymptomatic, permanent, focal dilatation of the abdominal aorta progressing towards rupture, which confers significant mortality. Patient management and surgical decisions rely on aortic diameter measurements via abdominal ultrasound surveillance. However, AAA rupture can occur at small diameters or may never occur at large diameters, implying that anatomical size is not necessarily a sufficient indicator. Molecular imaging may help identify high-risk patients through AAA evaluation independent of aneurysm size, and there is the question of the potential role of positron emission tomography (PET) and emerging role of novel radiotracers for AAA. Therefore, this review summarizes PET studies conducted in the last 10 years and discusses the usefulness of PET radiotracers for AAA risk stratification. The most frequently reported radiotracer was [18F]fluorodeoxyglucose, indicating inflammatory activity and reflecting the biomechanical properties of AAA. Emerging radiotracers include [18F]-labeled sodium fluoride, a calcification marker, [64Cu]DOTA-ECL1i, an indicator of chemokine receptor type 2 expression, and [18F]fluorothymidine, a marker of cell proliferation. For novel radiotracers, preliminary trials in patients are warranted before their widespread clinical implementation. AAA rupture risk is challenging to evaluate; therefore, clinicians may benefit from PET-based risk assessment to guide patient management and surgical decisions.

Morphohistological analysis of the prevalence and distribution of atheroma in the abdominal aorta and its branches: a cadaveric study

Background

Aneurysms and atheromatous processes are prominent pathological features that are commonly associated with significant morbidity and mortality.

Objectives

This cadaveric study was conducted to evaluate the morphometric and histological aspects of atheromatous plaque formation in abdominal aortas and their branches and their associated morphological variations, if present, characterized by loops, kinking, or tortuosity.

Methods

The study was performed using 30 human cadavers (approx. 65-75 years). Frequency of occurrence of calcified plaques in the abdominal aorta and its branches and their morphometric measurements were noted and histological features were observed with the aid of Hematoxylin & Eosin staining.

Results

Variations in the abdominal aorta and the common iliac artery were observed in 16.6% of specimens. Atheromatous plaque formation was seen in 2 specimens (1 specimen was associated with kinking) while in 3 other specimens only variation in normal structure (kinking/ tortuous artery) was observed. Histological analysis showed foamy macrophages and dense calcification, giving an atheromatous appearance.

Conclusions

Cadaveric reports of the location, nature, and degree of plaque formation in the abdominal aorta and its branches are extremely important in clinical settings and for choosing treatment options.

Screening Older Adult Men for Abdominal Aortic Aneurysm: A Scoping Review

Abdominal aortic aneurysm (AAA) is a potentially fatal condition predominantly affecting older adult men (60 years or over). Based on evidence, preventative health-care guidelines recommend screening older males for AAA using ultrasound. In attempts to reduce AAA mortality among men, screening has been utilized for early detection in some Western countries including the UK and Sweden. The current scoping review includes 19 empirical studies focusing on AAA screening in men. The findings from these studies highlight benefits and potential harms of male AAA screening. The benefits of AAA screening for men include decreased incidence of AAA rupture, decreased AAA mortality, increased effectiveness of elective AAA repair surgery, and cost-effectiveness. The potential harms of AAA screening included lack of AAA mortality reduction, negative impacts on quality of life, and inconsistent screening eligibility criteria being applied by primary care practitioners. The current scoping review findings are discussed to suggest changes to AAA screening guidelines and improve policy and practice.

Long Noncoding RNA SNHG16 Facilitates Abdominal Aortic Aneurysm Progression through the miR-106b-5p/STAT3 Feedback Loop

AIM

Deepening our understanding of the molecular mechanism of abdominal aortic aneurysm (AAA) progression will help set up novel avenues for therapeutic target identification. Our aim here was to unveil the mechanism function of STAT3 in AAA progression.

METHODS

We investigated the functional role of STAT3 in AAA by evaluating vascular smooth muscle cell (VSMC) apoptosis and proliferation via terminal deoxynucleotidyl transferase dUTP nick end labeling, western blotting, 5-ethynyl-2´-deoxyuridine, and Cell Counting Kit-8 assays. The interplay of lncRNA-miRNA-mRNA was verified using the luciferase reporter assay and the RNA pull-down, RNA immunoprecipitation, and chromatin immunoprecipitation assays. Quantitative real-time polymerase chain reaction and western blot were utilized to quantitate the RNA and protein levels of the indicated molecules.

RESULTS

Inhibition of STAT3 facilitated VSMC proliferation and repressed VSMC apoptosis. Moreover, It was demonstrated that small nucleolar RNA host gene 16 (SNHG16) sponged miR-106b-5p to release STAT3 from the inhibitory effect of miR-106b-5p. SNHG16 led to the upregulation of STAT3, and STAT3 was an upstream factor in the activation of SNHG16 transcription. Moreover, rescue experiments indicated that SNHG16 depended on STAT3 to regulate VSMC apoptosis and proliferation. In vivo assays showed that SNHG16 knockdown retarded the formation of AAA and upregulated STAT3 in vivo.

CONCLUSIONS

We identified that SNHG16/miR-106b-5p/STAT3 formed a complex circuitry for the deterioration of AAA via regulating VSMCs, suggesting a possible target for the pathogenesis of AAA.

Methane Exhalation Can Monitor the Microcirculatory Changes of the Intestinal Mucosa in a Large Animal Model of Hemorrhage and Fluid Resuscitation

Background: Internal hemorrhage is a medical emergency, which requires immediate causal therapy, but the recognition may be difficult. The reactive changes of the mesenteric circulation may be part of the earliest hemodynamic responses to bleeding. Methane is present in the luminal atmosphere; thus, we hypothesized that it can track the intestinal circulatory changes, induced by hemorrhage, non-invasively. Our goal was to validate and compare the sensitivity of this method with an established technique using sublingual microcirculatory monitoring in a large animal model of controlled, graded hemorrhage and the early phase of following fluid resuscitation.

Materials and Methods: The experiments were performed on anesthetized, ventilated Vietnamese minipigs (approval number: V/148/2013; n = 6). The animals were gradually bled seven times consecutively of 5% of their estimated blood volume (BV) each, followed by gradual fluid resuscitation with colloid (hydroxyethyl starch; 5% of the estimated BV/dose) until 80 mmHg mean arterial pressure was achieved. After each step, macrohemodynamic parameters were recorded, and exhaled methane level was monitored continuously with a custom-built photoacoustic laser-spectroscopy unit. The microcirculation of the sublingual area, ileal serosa, and mucosa was examined by intravital videomicroscopy (Cytocam-IDF, Braedius).

Results: Mesenteric perfusion was significantly reduced by a 5% blood loss, whereas microperfusion in the oral cavity deteriorated after a 25% loss. A statistically significant correlation was found between exhaled methane levels, superior mesenteric artery flow (r = 0.93), or microcirculatory changes in the ileal serosa (ρ = 0.78) and mucosa (r = 0.77). After resuscitation, the ileal mucosal microcirculation increased rapidly [De Backer score (DBS): 2.36 ± 0.42 vs. 8.6 ± 2.1 mm⁻¹], whereas serosal perfusion changed gradually and with a lower amplitude (DBS: 2.51 ± 0.48 vs. 5.73 ± 0.75). Sublingual perfusion correlated with mucosal (r = 0.74) and serosal (r = 0.66) mesenteric microperfusion during the hemorrhage phase but not during the resuscitation phase.

Conclusion: Detection of exhaled methane levels is of diagnostic significance during experimental hemorrhage as it indicates blood loss earlier than sublingual microcirculatory changes and in the early phase of fluid resuscitation, the exhaled methane values change in association with the mesenteric perfusion and the microcirculation of the ileum.

3D Automatic Segmentation of Aortic Computed Tomography Angiography Combining Multi-View 2D Convolutional Neural Networks

PURPOSE

The quantitative analysis of contrast-enhanced Computed Tomography Angiography (CTA) is essential to assess aortic anatomy, identify pathologies, and perform preoperative planning in vascular surgery. To overcome the limitations given by manual and semi-automatic segmentation tools, we apply a deep learning-based pipeline to automatically segment the CTA scans of the aortic lumen, from the ascending aorta to the iliac arteries, accounting for 3D spatial coherence.

METHODS

A first convolutional neural network (CNN) is used to coarsely segment and locate the aorta in the whole sub-sampled CTA volume, then three single-view CNNs are used to effectively segment the aortic lumen from axial, sagittal, and coronal planes under higher resolution. Finally, the predictions of the three orthogonal networks are integrated to obtain a segmentation with spatial coherence.

RESULTS

The coarse segmentation performed to identify the aortic lumen achieved a Dice coefficient (DSC) of 0.92 ± 0.01. Single-view axial, sagittal, and coronal CNNs provided a DSC of 0.92 ± 0.02, 0.92 ± 0.04, and 0.91 ± 0.02, respectively. Multi-view integration provided a DSC of 0.93 ± 0.02 and an average surface distance of 0.80 ± 0.26 mm on a test set of 10 CTA scans. The generation of the ground truth dataset took about 150 h and the overall training process took 18 h. In prediction phase, the adopted pipeline takes around 25 ± 1 s to get the final segmentation.

CONCLUSION

The achieved results show that the proposed pipeline can effectively localize and segment the aortic lumen in subjects with aneurysm.

Comparison of the Short and Long-Term Outcomes of Endovascular Repair and Open Surgical Repair in the Treatment of Unruptured Abdominal Aortic Aneurysms: Meta-Analysis and Systematic Review

Background

Although the initial results of endovascular repair (EVAR) were promising, a comparison of its long-term efficacy against open surgical repair (OSR) remains largely elusive, and late-onset adverse events have not been systematically evaluated. Since OSR and EVAR are currently the only treatment options available in the management of abdominal aortic aneurysms (AAAs), the main question arising in clinical practice is whether EVAR or OSR confers more favourable short and long-term outcomes for patients presenting with unruptured AAAs.

Aims

The present meta-analysis aims to draw a head-to-head comparison between EVAR and OSR and facilitate the formulation of an evidence-based approach to the clinical management of unruptured AAAs.

Methods

A systematic review was conducted using three databases to identify all relevant studies with comparative data on EVAR vs. OSR. All-cause mortality was the primary outcome. Procedural outcomes, such as stroke, myocardial infarction, renal complications, rupture, and reintervention rates, were determined as secondary outcomes.

Results

Sixteen studies were included for comparative analysis, including four randomised-controlled trials and six non-randomised comparative clinical trials. EVAR conferred a clear perioperative survival advantage as compared to OSR (P < 0.00001). However, this survival advantage did not persist beyond two years post-procedure; all-cause mortality rates were comparable between the two treatment groups at two years (P = 0.09), four years (P = 0.58), and six years (P = 0.88) post-procedure. Although no statistically significant differences in aneurysm-related mortality, postoperative stroke, or myocardial infarction were identified, the OSR group had a statistically significant higher rate of postoperative renal complications. On the other hand, there was a statistically significant higher rate of rupture and reintervention following EVAR.

Conclusion

Whether the initial survival advantage afforded by EVAR is sufficient to justify the long-term risk of rupture, reintervention, and long-term mortality should be determined on a case-by-case basis by the multidisciplinary team overseeing the clinical care of the patient. Currently, it is reasonable to conclude that EVAR is as efficacious as OSR, but it would be invalid to claim it as superior. Ultimately, longer follow-up data must be presented before any definitive conclusions can be established for this potentially revolutionary technique. Presently, one can neither advocate nor refute EVAR over OSR.

Targeted Drug Delivery of Microbubble to Arrest Abdominal Aortic Aneurysm Development: A Simulation Study Towards Optimized Microbubble Design

Abdominal aortic aneurysm (AAA) is an irreversible bulge in the artery with higher prevalence among the elderlies. Increase of the aneurysm diameter by time is a fatal phenomenon which will lead to its sidewall rupture. Invasive surgical treatments are vital in preventing from AAA development. These approaches however have considerable side effects. Targeted drug delivery using microbubbles (MBs) has been recently employed to suppress the AAA growth. The present study is aimed to investigate the surface adhesion of different types of drug-containing MBs to the inner wall of AAA through ligand-receptor binding, using fluid-structure interaction (FSI) simulation by using a patient CT-scan images of the vascular system. The effect of blood flow through AAA on MBs delivery to the intended surface was also addressed. For this purpose, the adherence of four types of MBs with three different diameters to the inner surface wall of AAA was studied in a patient with 40-mm diameter aneurysm. The effects of the blood mechanical properties on the hematocrit (Hct) percentage of patients suffering from anemia and diabetes were studied. Moreover, the impact of variations in the artery inlet velocity on blood flow was addressed. Simulation results demonstrated the dependency of the surface density of MBs (SDM) adhered on the AAA lumen to the size and the type of MBs. It was observed that the amount of SDM due to adhesion on the AAA lumen for one of the commercially-approved MBs (Optison) with a diameter of 4.5 μm was higher than the other MBs. Furthermore, we have shown that the targeted drug delivery to the AAA lumen is more favorable in healthy individuals (45% Hct) compared to the patients with diabetes and anemia. Also, it was found that the targeted drug delivery method using MBs on the patients having AAA with complicated aneurysm shape and negative inlet blood flow velocity can be severely affected.

Multidetector Computed Tomography in Traumatic and Nontraumatic Aortic Emergencies: Emphasis on Acute Aortic Syndromes

Aortic emergencies comprise of a list of conditions which are uncommon but are potentially fatal. Prognosis is usually determined by emergent diagnosis and treatment and hence radiology plays a key role in patient management. In this article, we aim to review the various causes of aortic emergencies and the relevant imaging findings placing special emphasis on acute aortic syndromes.

Genetic and epigenetic regulation of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are focal dilations of the aorta that develop from degenerative changes in the media and adventitia of the vessel. Ruptured AAAs have a mortality of up to 85%, thus it is important to identify patients with AAA at increased risk for rupture who would benefit from increased surveillance and/or surgical repair. Although the exact genetic and epigenetic mechanisms regulating AAA formation are not completely understood, Mendelian cases of AAA, which result from pathologic variants in a single gene, have helped provide a basic understanding of AAA pathophysiology. More recently, genome wide associated studies (GWAS) have identified additional variants, termed single nucleotide polymorphisms, in humans that may be associated with AAAs. While some variants may be associated with AAAs and play causal roles in aneurysm pathogenesis, it should be emphasized that the majority of SNPs do not actually cause disease. In addition to GWAS, other studies have uncovered epigenetic causes of disease that regulate expression of genes known to be important in AAA pathogenesis. This review describes many of these genetic and epigenetic contributors of AAAs, which altogether provide a deeper insight into AAA pathogenesis.

Point-of-care Ultrasound Trumps Computed Tomography in a Case of Abdominal Aortic Aneurysm Assessment

Patients who present to the emergency department (ED) with aortic emergencies can be some of the highest acuity patients that we manage. Ultrasonography performed at the bedside is traditionally considered to be a screening test that is especially useful in the unstable patient. Computed tomography (CT) with angiography is the imaging modality of choice to confirm the diagnosis and plan the management of abdominal aortic aneurysm (AAA), as an ultrasound is generally thought not to provide the clinician with sufficient anatomical information. We present a case of a patient with an abdominal aortic aneurysm where evidence obtained from the ultrasound provided more useful information regarding aneurysm structure and stability than did CT.

Knockdown of lncRNA PVT1 Inhibits Vascular Smooth Muscle Cell Apoptosis and Extracellular Matrix Disruption in a Murine Abdominal Aortic Aneurysm Model

This study was designed to determine the effects of the long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) on vascular smooth muscle cell (VSMC) apoptosis and extracellular matrix (ECM) disruption in a murine abdominal aortic aneurysm (AAA) model. After injection of PVT1-silencing lentiviruses, AAA was induced in Apolipoprotein E-deficient (ApoE-/-) male mice by angiotensin II (Ang II) infusion for four weeks. After Ang II infusion, mouse serum levels of pro-inflammatory cytokines were analysed, and aortic tissues were isolated for histological, RNA, and protein analysis. Our results also showed that PVT1 expression was significantly upregulated in abdominal aortic tissues from AAA patients compared with that in controls. Additionally, Ang II treatment significantly increased PVT1 expression, both in cultured mouse VSMCs and in AAA murine abdominal aortic tissues. Of note, the effects of Ang II in facilitating cell apoptosis, increasing matrix metalloproteinase (MMP)-2 and MMP-9, reducing tissue inhibitor of MMP (TIMP)-1, and promoting switching from the contractile to synthetic phenotype in cultured VSMCs were enhanced by overexpression of PVT1 but attenuated by knockdown of PVT1. Furthermore, knockdown of PVT1 reversed Ang II-induced AAA-associated alterations in mice, as evidenced by attenuation of aortic diameter dilation, marked adventitial thickening, loss of elastin in the aorta, enhanced aortic cell apoptosis, elevated MMP-2 and MMP-9, reduced TIMP-1, and increased pro-inflammatory cytokines. In conclusion, our findings demonstrate that knockdown of lncRNA PVT1 suppresses VSMC apoptosis, ECM disruption, and serum pro-inflammatory cytokines in a murine Ang II-induced AAA model.

Low Back Pain: A Pain That May Not Be Harmless

Abdominal aortic aneurysms are defined as vascular dilatations greater than 50% of the normal proximal segment or those that have a maximum diameter above 3 cm. Risk factors include male gender, age over 75 years, history of vascular pathology, hypertension and arteriosclerosis. The Authors describe a case of a 74-year-old man, evaluated in an emergency setting for right lumbar pain lasting 4 days. The pain did not respond to analgesia and became progressively worse. Due to the severity of symptoms, CT angiography was performed, which showed an active rupture of a partially contained aneurysm associated with aortic dissection. Early diagnosis and timely management of aortic aneurysms are essential in preventing complications, namely rupture (50–83% patients die after rupture and before receiving medical care). Acute aortic dissection is a surgical emergency and the risk of rupture is proportional to the size of the aneurysm and its rate of growth.

Red blood cell distribution width (RDW) is an independent predictor of post-implantation syndrome in patients undergoing endovascular aortic repair for abdominal aortic aneurysm

Background

This observational, retrospective study aims establishing the role of red blood cell distribution width (RDW) for identifying abdominal aortic aneurism (AAA) patients at risk of developing post-implantation syndrome (PiS) after endovascular aneurysm repair (EVAR).

Methods

The study population consisted of all patients undergoing EVAR for AAA at the University Hospital of Verona (Italy), between June 1, 2016 and May 31, 2018. Blood samples for measuring hemoglobin, mean corpuscular volume (MCV) and RDW were collected at hospital admission and the day after EVAR. The primary endpoint was PiS development. Delta variations were calculated as the ratio between values measured after and before EVAR.

Results

The final study population consisted of 124 patients (10 women and 114 men; median age, 75 years), 55 of whom developed PiS. In patients with or without PiS hemoglobin significantly decreased after EVAR, whilst RDW significantly increased in patients with PiS and decreased in those without. Age, sex, hypertension, diabetes and renal failure were similar in patients who developed PiS or not, whilst a positive history of coronary artery disease was more frequent in PiS patients. Although hemoglobin and MCV changes after EVAR did not differ in patients with or without PiS, delta RDW was higher in those with PiS. The rate of patients with delta RDW >1 was significantly higher in patients with PiS that in those without (61.8% vs. 34.8%; P=0.002). In multivariate analysis, delta RDW remained independently associated with PiS (β coefficient, 2.023; P=0.001). A delta RDW >1 after EVAR was associated with ~3-fold enhanced risk of PiS (odds ratio, 3.04; P=0.003) and exhibited a good prognostic performance (area under the curve, 0.69; P<0.001).

Conclusions

Calculation of delta RDW after EVAR seems an efficient prognostic tool for stratifying the risk of developing PiS, especially in the early postoperative period.

Inhibitory effects of cycloastragenol on abdominal aortic aneurysm and its related mechanisms

BACKGROUND AND PURPOSE

Abdominal aortic aneurysm (AAA) is a degenerative disease affecting human health, but there are no safe and effective medications for AAA therapy. Cycloastragenol (CAG), derived from Astragali Radix, has various pharmacological effects. However, whether CAG can protect against AAA remains elusive. In this study, we investigated whether CAG has an inhibitory effect on AAA and its related mechanism.

EXPERIMENTAL APPROACH

The AAA mouse model was induced by incubating the abdominal aorta with elastase. CAG was administered by gavage at different doses beginning on the same day or 14 days after inducing AAA to explore its preventive or therapeutic effects respectively. The preventive effects of CAG on AAA were verified in another AAA mouse model induced by angiotensin II in ApoE-/- mouse. In vitro experiments were implemented on rat vascular smooth muscle cells (VSMCs) stimulated by TNF-α.

KEY RESULTS

Compared to the control AAA model group, CAG (125 mg·kg-1 body weight day-1 ) reduced the incidence of AAA, the dilatation of aorta and elastin degradation in media in both mouse models of AAA. CAG suppressed the inflammation, oxidation, phenotype switch and apoptosis in TNF-α-stimulated VSMCs, ameliorated the expression and activity of MMPs and decreased the activation of the ERK/JNK signalling pathway. CAG also inhibited the degradation of elastin in TNF-α-stimulated VSMCs.

CONCLUSION AND IMPLICATIONS

CAG presents protective effects against AAA through down-regulation of the MAPK signalling pathways and thus attenuates inflammation, oxidation, VSMC phenotype switch and apoptosis and the expression of MMPs as well as increasing elastin biosynthesis.

Characterization of CD4+ T Cell Subsets in Patients with Abdominal Aortic Aneurysms

BACKGROUND

The mediators produced by CD4+ T lymphocytes are involved in the pathogenesis of aneurysmal lesions in abdominal aortic aneurysm (AAA) patients. The aim of this study was to identify and characterize the CD4+ T cell subsets involved in human AAA.

METHODS

The CD4+ T cell subsets in 30 human aneurysmal lesions were determined using flow cytometry (FC) and immunohistochemistry (IHC). The peripheral blood mononuclear cells (PBMCs) from patients with AAA were also analyzed by FC and compared with control subjects.

RESULTS

Human aneurysmal lesions contained IFN-γ, IL-12p35, IL-4, IL-23p19, IL-17R, and IL-22 positive cells. PBMCs from AAA patients had higher expression levels of IFN-γ, TNF-α, IL-4, and IL-22 when compared to controls.

CONCLUSIONS

Our results show the presence of TH1, TH2, TH17, and TH22 subsets in aneurysmal lesions of AAA patients and suggest that these cells may be mainly activated in situ, where they can induce tissue degradation and contribute to the pathogenesis of AAA.

Computed tomographic diagnosis of aortocaval fistula

Aortocaval fistula is an abnormal vascular communication between an aortic aneurysm and the inferior vena cava. The condition is very rare and life threatening with high mortality. This article reports a case of aortocaval fistula in a 76-year-old male diagnosed using computed tomography. Computed tomography, being a non-invasive investigation, ensures early diagnosis and can help in prompt surgical or interventional radiological management which can be life-saving.

Abdominal aortic aneurysm screening: concepts and controversies

Abdominal aortic aneurysms (AAAs) are a leading cause mortality and morbidity but often go undiagnosed until late stages unless imaging is performed. In 2005, the United States Preventive Services Task Force (USPSTF) for the first time recommended one-time ultrasound screening for elderly male smokers and selective screening in other populations. These guidelines were reaffirmed and updated in 2014; a proposal for potential further revisions is now in early planning stages. In this article, we review the past and current USPSTF AAA screening recommendations and techniques for performing optimal screening. Evidence supporting screening and alternative guidelines are also discussed. In addition, emerging concepts and controversies in AAA screening are highlighted, including conflicting data on screening benefits, screening underutilization, inconsistent follow-up recommendations, and the potential for duplicative testing, alternative screening modalities, and clinically significant incidental findings.

Idiopathic Giant Hepatic Artery Pseudoaneurysm

Hepatic artery pseudoaneurysm (HAP) incidence is rising due to more common use of endoscopic and percutaneous hepatic interventions. HAP is potentially fatal, as it could lead to sudden life-threatening hemorrhage. HAP can be intrahepatic or extrahepatic. On computed tomography angiogram (CTA) and magnetic resonance angiogram (MRA), HAP follows blood pool on multiphasic examination, with brisk arterial enhancement that washes out, similar to the abdominal aorta on later phases. We present a case of idiopathic giant HAP in an 82-year-old male. Currently, angioembolization is replacing surgery as the initial modality of choice for management of this condition.