Clinicopathological study on penetrating atherosclerotic ulcers and aortic dissection: distinct pattern of development of initial event

Acute Aortic Syndrome Revisited: JACC State-of-the-Art Review

The purpose of this paper is to describe all available evidence on the distinctive features of a group of 4 life-threatening acute aortic pathologies gathered under the name of acute aortic syndrome (AAS). The epidemiology, diagnostic strategy, and management of these patients has been updated. The authors propose a new and simple diagnostic algorithm to support clinical decision making in cases of suspected AAS, thereby minimizing diagnostic delays, misdiagnoses, and unnecessary advanced imaging. AAS-related entities are reviewed, and a guideline to avoid imaging misinterpretation is provided. Centralization of patients with AAS in high-volume centers with high-volume surgeons is key to improving clinical outcomes. Thus, the role of multidisciplinary teams, an "aorta code" (streamlined emergent care pathway), and aortic centers in the management of these patients is boosted. A tailored patient treatment approach for each of these acute aortic entities is needed, and as such has been summarized. Finally, a set of prevention measures against AAS is discussed.

Management of the penetrating atherosclerotic ulcer in the descending thoracic aorta

Penetrating atherosclerotic ulcers present with an insidious onset with a reported mortality of 9%, varying across populations. With vast arrays of risk factors and potentially ominous complications, it is vital to efficiently provide optimum strategies for management. There exists controversy in the literature regarding management, especially for Type B penetrating atherosclerotic ulcers; the decision-making framework encompasses numerous factors in considerations for medical management versus invasive intervention and choice of endovascular versus open repair in the latter. The concomitant presence of intramural haematoma adds further complexity to the already intricate decision-making for management. We performed searches through PubMed and SCOPUS analysing studies reporting outcomes for management strategies for penetrating atherosclerotic ulcers treatment, focusing on Type B, further seeking to analyse studies reporting their experiences of PAU patients with concomitant intramural haematoma. Our review highlights the ambiguity and controversy existing in the literature, comprising studies burdened by their inherent hindering limitations of their single-centre retrospective experiences. Endovascular therapy has come to the forefront of penetrating atherosclerotic ulcers management, often considered first line therapy. In the case of penetrating atherosclerotic ulcers alongside intramural haematoma, there have been reports of potential hybrid surgical approaches to management. Studies further show misdiagnosis of penetrating atherosclerotic ulcers in earlier data sets further complicates management. However, it is clear we must progress on the journey towards precision medicine, allowing delivery of optimum care to our patients.

Computational Investigation and Histopathological Validation of Interaction Between Stent Graft and Aorta in Retrograde Type A Dissection After TEVAR in Canine Models

PURPOSE

Retrograde type A dissection (RTAD) after thoracic endovascular aortic repair (TEVAR) has been a major drawback of endovascular treatment. To our knowledge, no studies have simulated and validated aortic injuries caused by stent grafts (SGs) in animal models. Therefore, the aim of this study was to evaluate and quantify the SG-aorta interaction through computational simulations and to investigate the underlying mechanism through histopathological examinations.

METHODS

Two custom-made Fabulous^® (DiNovA Meditech, Hang Zhou, China) SGs were implanted in 2 canine aortas with a 5-mm difference in the distance in landing locations. The aortic geometries were extracted from RTAD and non-RTAD cases. A computational SG model was assembled based on the implanted SG using the software Pro-ENGINEER Wildfire 5.0 (PTC Corporation, Needham, Mass). TEVAR simulations were performed 7 times for each canine model using Abaqus software (Providence, RI, USA), and the maximum aortic stress (MAS) was calculated and compared among the groups. Three months after SG implantation, the canine aortas were harvested, and were examined using hematoxylin and eosin staining and Elastica Van Gieson (EVG) staining to evaluate histopathological changes.

RESULTS

In the computational models for both canines, MAS was observed at the proximal bare stent (PBS) at aortic greater curve. The PBS generated higher stress toward the aortic wall than other SG parts did. Moreover, the MAS was significantly higher in canine No.1 than in canine No.2 (0.415±0.210 versus 0.200±0.160 MPa) (p<0.01). Notably, in canine No.1, an RTAD developed at the MAS segment, and histopathological examinations of the segment showed an intimal flap, a false lumen, elastin changes, and medial necrosis. RTAD was not observed in canine No.2. In both SG-covered aortas, medial necrosis, elastic fiber stretching, and inflammatory infiltration were seen.

CONCLUSION

The characteristic MAS distribution remained at the location where the apex of the PBS interacted with the aortic wall at greater curve. RTAD histopathological examinations showed intimal damage and medial necrosis at the proximal landing zone, at the same MAS location in computational simulations. The in vivo results were consistent with the computational simulations, suggesting the MAS at greater curve may cause RTAD, and the potential application of computational simulation in the mechanism study of RTAD.

Chest CT Angiography for Acute Aortic Pathologic Conditions: Pearls and Pitfalls

Chest CT angiography (CTA) is essential in the diagnosis of acute aortic syndromes. Chest CTA quality can be optimized with attention to technical parameters pertaining to noncontrast imaging, timing of contrast-enhanced imaging, contrast material volume, kilovolt potential, tube-current modulation, and decisions regarding electrocardiographic-gating and ultra-fast imaging, which may affect the accurate diagnosis of acute aortic syndromes. An understanding of methods to apply to address suboptimal image quality is useful, as the accurate identification of acute aortic syndromes is essential for appropriate patient management. Acute aortic syndromes have high morbidity and mortality, particularly when involving the ascending aorta, and include classic aortic dissection, penetrating atherosclerotic ulcer, and acute intramural hematoma. An understanding of the pathogenesis and distinguishing imaging features of acute aortic syndromes and aortic rupture and some less common manifestations is helpful when interpreting imaging examinations. Related entities, such as ulcerated plaque, ulcerlike projections, and intramural blood pools, and mimics, such as vasculitis and aortic thrombus, are important to recognize; knowledge of these is important to avoid interpretive pitfalls. In addition, an awareness of postsurgical aortic changes can be useful when interpreting CTA examinations when patient history is incomplete. The authors review technical considerations when performing CTA, discuss acute aortic syndromes, and highlight diagnostic challenges encountered when interpreting aortic CTA examinations. ^©RSNA, 2021.

Long-Term Imaging Evolution and Clinical Prognosis Among Patients With Acute Penetrating Aortic Ulcers: A Retrospective Observational Study

Background Acute penetrating aortic ulcers (PAUs) are reported to dynamically evolve into different clinical outcomes ranging from regression to aortic rupture, but no practice guidelines are available in China. Methods and Results All 109 patients with acute PAUs were monitored clinically. At 30 days follow-up, 31 patients (28.44%) suffered from aortic-related adverse events, a composite of aortic-related mortality, aortic dissection, or an enlarged ulcer. In addition, 7 (6.42%) patients had clinically related adverse events, including all-cause mortality, cerebral stroke, nonfatal myocardial infarction, acute heart failure alone or acute exacerbation of chronic heart failure, acute renal failure, arrhythmia, and bleeding events. In the present study, the intervention criteria for the Chinese PAU population included a PAU diameter of 12.5 mm and depth of 9.5 mm. The multivariate analysis showed that an ulcer diameter >12.5 mm (hazard ratio [HR], 3.846; 95% CI, 1.561-9.476; P=0.003) and an ulcer depth >9.5 mm (HR, 3.359; 95% CI, 1.505-7.494; P=0.003) were each independent predictors of aortic-related events. Conclusions Patients with acute PAUs were at high risk for aortic-related adverse events and clinically related adverse events within 30 days after onset. Patients with an ulcer diameter >12.5 mm or an ulcer depth >9.5 mm have a higher risk for disease progression, and early intervention may be recommended.

Body Mass Index and Mortality From Aortic Aneurysm and Dissection

AIMS

Reports on an association between body mass index and aortic disease, which remains controversial. This study investigated the association between body mass index and mortality from aortic disease.

METHODS

We conducted the Japan Collaborative Cohort Study, a prospective study of 103,972 Japanese men and women aged 40-79 years. Body mass index was calculated on the basis of self-reported height and weight, and the participants were followed up from 1988-89 through 2009. Sex-specific hazard ratios (95% confidence intervals) of mortality from aortic disease according to quintiles of body mass index were analyzed using the Cox proportional hazards model.

RESULTS

During the median 18.8 years of follow-up, we documented 139 deaths due to aortic aneurysm (including 51 thoracic and 74 abdominal aortic aneurysms) and 134 deaths due to aortic dissection. We observed positive associations of body mass index with mortality from aortic aneurysm among men: the multivariable hazard ratios (95% confidence intervals) for highest versus lowest quintiles of body mass index were 4.48 (2.10-9.58), P for trend ＜0.0001 for aortic aneurysm; 6.52 (1.33-32.02), P=0.005 for thoracic aortic aneurysm; 3.81 (1.39-10.49), P=0.01 for abdominal aortic aneurysm; and 2.71 (1.59-4.62), P=0.001 for total aortic disease. No association was found for aortic dissection. Among ever-smokers (men ≥ 90%) but not never-smokers (women ≥ 84%), an association between body mass index and aortic disease mortality was observed regardless of sex, which may explain the sex difference (P for sex-interaction=0.046).

CONCLUSIONS

We found a positive association between body mass index and mortality from aortic aneurysm among Japanese men and smokers.

Mechanical and structural properties of different types of human aortic atherosclerotic plaques

Atherosclerotic plaques are characterized by structural heterogeneity affecting aortic behaviour under mechanical loading. There is evidence of direct connections between the structural plaque arrangement and the risk of plaque rupture. As a consequence of aortic plaque rupture, plaque components are transferred by the bloodstream to smaller vessels, resulting in acute cardiovascular events with a poor prognosis, such as heart attacks or strokes. Hence, evaluation of the composition, structure, and biochemical profile of atherosclerotic plaques seems to be of great importance to assess the properties of a mechanically induced failure, indicating the strength and rupture vulnerability of plaque. The main goal of the research was to determine experimentally under uniaxial loading the mechanical properties of different types of the human abdominal aorta and human aortic atherosclerotic plaques identified based on vibrational spectra (ATR-FTIR and FT-Raman spectroscopy) analysis and validated by histological staining. The potential of spectroscopic techniques as a useful histopathological tool was demonstrated. Three types of atherosclerotic plaques - predominantly calcified (APC), lipid (APL), and fibrotic (APF) - were distinguished and confirmed by histopathological examinations. Compared to the normal aorta, fibrotic plaques were stiffer (median of E_H for circumferential and axial directions, respectively: 8.15 MPa and 6.56 MPa) and stronger (median of σ_M for APLc = 1.57 MPa and APLa = 1.64 MPa), lipidic plaques were the weakest (median of σ_M for APLc = 0.76 MPa and APLa = 0.51 MPa), and calcified plaques were the stiffest (median of E_H for circumferential and axial directions, respectively: 13.23 MPa and 6.67 MPa). Therefore, plaques detected as predominantly lipid and calcified are most prone to rupture; however, the failure process reflected by the simplification of the stress-stretch characteristics seems to vary depending on the plaque composition.

Updates on Computed Tomography Imaging in Aortic Aneurysms and Dissection

Computed tomography (CT) is a primary imaging modality for the diagnosis of aortic diseases, because of its minimal invasiveness and agility.

Prompt and accurate diagnosis is crucial especially for acute aortic diseases, and the guidelines for acute aortic dissection recommend the use of CT for initial diagnosis. For the follow-up observation of longstanding aortic diseases, the strategy of imaging management by CT must be different from that for emergency and acute phases.

In this review, we document the differences in characteristics and clinical course between aortic aneurysm and aortic dissection and explain the use of recent CT techniques in diagnosing short- and longstanding aortic diseases.

Society for Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) Reporting Standards for Type B Aortic Dissections

This Society for Vascular Surgery/Society of Thoracic Surgeons (SVS/STS) document illustrates and defines the overall nomenclature associated with type B aortic dissection. The contents describe a new classification system for practical use and reporting that includes the aortic arch. Chronicity of aortic dissection is also defined along with nomenclature in patients with prior aortic repair and other aortic pathologic processes, such as intramural hematoma and penetrating atherosclerotic ulcer. Complicated vs uncomplicated dissections are clearly defined with a new high-risk grouping that will undoubtedly grow in reporting and controversy. Follow-up criteria are also discussed with nomenclature for false lumen status in addition to measurement criteria and definitions of aortic remodeling. Overall, the document provides a facile framework of language that will allow more granular discussions and reporting of aortic dissection in the future.

Aortic Plaque Distribution, and Association between Aortic Plaque and Atherosclerotic Risk Factors: An Aortic Angioscopy Study

Aim: Knowledge of subclinical plaque morphology and plaque distribution in the aorta in vivo remains unclear. This study aimed to increase the body of knowledge in this area.

Methods: We enrolled 37 consecutive patients with stable angina pectoris patients who underwent non-obstructive angioscopy for both the coronary artery and aorta immediately after percutaneous coronary intervention. We evaluated the presence of aortic plaques and the distribution of plaque instability. Patients were allocated into two groups according to the number of vulnerable plaques in whole aorta (a low [0–11] and high [≥ 12] group). We evaluated the relationships between the two groups in terms of cardiovascular risk factors.

Results: Aortic plaques were identified using non-obstructive angioscopy in all patients, and the greatest number of plaques was found at the infrarenal abdominal aorta (IAA) (the aortic arch, the descending thoracic aorta, the suprarenal abdominal aorta, the IAA, and common iliac artery; 65%, 76%, 65%, 95%, and 49%, respectively; p < 0.001). The maximum yellow grade, and the number of intense yellow plaques, ruptured plaques, and thrombi were highest at the IAA (p < 0.001). The prevalence of diabetes mellitus and peripheral arterial disease was higher in the high vulnerable plaque group (83.3% vs. 40.0%, p = 0.010, 50.0% vs. 8.0%, p = 0.005, respectively).

Conclusions: Aortic atherosclerosis was the most severe at the IAA, and aortic plaque vulnerability and distribution were associated with the prevalence of diabetes mellitus and peripheral artery disease in patients with stable angina pectoris. Non-obstructive angioscopy may identify patients at high risk of future aortic events.

Long-term follow-up and clinical implications in Chinese patients with aortic intramural hematomas

BACKGROUND

Intramural hematomas (IMHs) are reported to dynamically evolve into different clinical outcomes ranging from regression to aortic rupture, but no practice guidelines are available in China.

OBJECTIVE

To determine the evolution of IMHs after long-term follow-up and to identify the predictive factors of IMH outcomes in the Chinese population.

METHODS

A total of 123 IMH patients with clinical and imaging follow-up data were retrospectively studied. The primary endpoints were aortic disease-related death, aortic dissection, penetrating aortic ulcer (PAU), thickening of the aortic hematoma and aortic complications requiring surgical or endovascular treatment.

RESULTS

All 123 IMH patients were monitored clinically. The follow-up duration ranged from 1.4 to 107 months (median, 20 months). Thirty-nine patients had type A IMH, and 84 had type B. The multivariate analysis showed that a baseline MAD ≥ 44.75 mm (2.9% vs 61.4%, P < 0.001) and acute PAUs (2.9% vs 34.1%, P = 0.008) were independent predictors of aorta-related events.

CONCLUSIONS

Medication and short-term imaging are recommended for Chinese IMH patients with a hematoma thickness < 10.45 mm and a baseline MAD < 44.75 mm. Rigorous medical observation should also be performed during the acute phase of IMH.