Histopathological evaluation of aortic dissection: a comparison of congenital versus acquired aortic wall weakness

Evaluation of the Value of Histological Examination for the Prediction of Genetic Thoracic Proximal Aortopathies

Background: Heritable connective tissue disorders are often accompanied by an increased risk for thoracic aortic aneurysm and dissection (TAAD). Profound knowledge of the underlying pathology may have an impact on individual treatment, systematic follow-up, and early detection by the screening of offspring. The aim of this study, based in a single high-volume tertiary center, was an analysis of the diagnostic validity of histopathologic findings in patients with TAAD due to these findings' accuracy in diagnosing heritable connective tissue disorders. Methods: Therefore, genetic testing by next-generation sequencing (NGS) was performed to evaluate the correlations. In total, 65 patients with TAAD undergoing surgical treatment before the age of 60 years or with age up to 80 years if they had offspring at the time of the procedure were included in the analysis. Results: In our cohort, no certain correlation of histological findings to the results of genetic diagnostics in patients with clinically relevant aortic pathology could be shown. Patients with histopathologic findings for heritable connective tissue disorder and a positive gene variant were 11.6 years younger than patients without mutation and without histological evidence for connective tissue disorder. Conclusions: Genetic clarification is useful to define the specific genotype of the disease of the aortic wall in the case of non-specific histological characteristics.

Prevention of distal stent graft-induced new entry after endovascular repair for type B aortic dissection: A retrospective cohort study

OBJECTIVES

Distal stent graft-induced new entry (dSINE) can occur after thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD). In this study we aimed to compare the effectiveness of restrictive bare stent (RBS), tapered stent graft (TSG), and non-TSG in TEVAR in preventing dSINE after a midterm follow-up.

METHODS

This retrospective cohort study included patients with TBAD who underwent TEVAR (June 2010 to December 2018). The occurrence of dSINE during follow-up was examined. Predictors of dSINE were determined using Fine-Gray regression with death as the competing event. Survival was evaluated using Cox proportional hazards regression.

RESULTS

Finally, 364 patients were included: 111 with non-TSG TEVAR, 125 with TSG TEVAR, and 128 with TEVAR with RBS. After 54.5 months, incidences of dSINE in the 3 groups were 12.61%, 4.80%, and 1.56%, respectively (P = .002). On Fine-Gray regression adjusted for clinically relevant covariates, the expansion mismatch ratio (subdistribution hazard ratio, 1.09; 95% CI, 1.07-1.12; P < .001) and complete false lumen thrombosis (subdistribution hazard ratio, 0.35; 95% CI, 0.13-0.94; P = .037) were identified as predictors of dSINE. The Cox proportional hazards regression analysis revealed that dSINE was not only a risk factor for aortic-related mortality (hazard ratio, 17.90; 95% CI, 3.27-98.12; P = .001), but also a predominant risk factor for all-cause mortality (hazard ratio, 4.91; 95% CI, 1.66-14.52; P = .004).

CONCLUSIONS

dSINE can happen in TBAD patients who undergo TEVAR. Thus, long-term surveillance is crucial. TSG and RBS had lower expansion mismatch ratios, which might help prevent dSINE.

Pathological Characteristics of the Vascular Septum in Chronic Aortic Dissection: A Case Report

A 46-year-old male developed a Stanford type B aortic dissection. At age 48, he underwent left open thoracic descending aorta replacement because of the enlargement of the descending thoracic aorta. At 51 years old, he underwent abdominal aorta replacement because of ischemia in the right lower extremity and the enlargement of an abdominal aortic aneurysm. The septum between the true and false lumens was submitted to histopathological examination, which revealed bilateral intimal tissue with the tunica media lying in between.

Histopathological Gap in Aortic Diseases: A Prospective Analysis

Aortic dissection (AD) is a critical cardiovascular condition with the potential for devastating consequences. This study evaluated the histological changes in the aorta wall in patients with AD and aortic aneurysm (AA) who received surgical aortic replacement. Histopathological data showed that modifications of the media layer (p = 0.0197), myxomatous aspect (p = 0.0001), and subendothelial layer degeneration (p = 0.0107) were more frequently seen in AA versus AD samples. Patients with AA were approximately twice as likely to develop histological changes than those with AD (p = 0.0037). Patients with moderate or severe medial degeneration had a higher chance of developing AD (p = 0.0001). Because the histopathological score proved to be a predictor of both in-hospital and overall mortality, its evaluation should become the standard of care in any patients who undergo aortic replacement. Individualized postoperative management might be influenced by the histopathological aspect of the aortic layer.

The Frozen Elephant Trunk Procedure Using New Russian Hybrid Prosthesis "Soft Elephant Trunk": the Early Experience

Aim      To present the first experience of performing the Frozen Elephant Trunk (FET) surgery in patients with thoracic aorta disease using a new Russian hybrid stent graft "Soft Elephant Trunk".Material and methods  Between 2014 and 2021, 170 patients with thoracic aortic disease underwent complete aortic arch replacement using the FET technique. In 70 of these cases (since June 2019), a hybrid graft "Soft Elephant Trunk" was used. A specific feature of this graft is the conical reduction of the radial force of nitinol crowns and the soft distal end without radial force. The study endpoints were early postoperative results, as well as the absence of reoperations on the aorta, absence of stent-graft-associated complications, including distal stent-graft-induced fenestration, and survival at a mid-term follow-up of up to 2.5 years.Results Interventions were performed in patients with A type aortic dissection (n=51; 72.9 %), type B aortic dissection (n=13; 18.6 %), and thoracoabdominal aortic aneurysm (TAAA) (n=6; 8.5 %). In 14 (20 %) of these cases, interventions were performed after a primary intervention on the proximal aorta. Acute aortic dissection was diagnosed in 17 (24.3 %) cases. Aortic root replacement was performed in 21 (30 %) cases, David procedure in 5 (7.2 %) cases, Bentall-DeBono procedure in 11 (15.7 %) cases, and supracoronary graft placement in 33 (47.1 %) cases. There were no cases of paraplegia or paraparesis. Respiratory insufficiency was observed in 8 (11.4%) cases. In one (1.4%) case, acute renal failure developed, which required renal replacement therapy. In-hospital mortality was 4.3 % (3 patients died). Mean follow-up duration was 9 [4.25; 16] months. Three-year survival was 94 % (95 % confidence interval, CI: 88-99.9) and absence of reoperation was 96.6 % (95 % CI: 90.1-100). There were no cases of distal stent-graft-induced fenestration in this group.Conclusion      The new hybrid graft, due to its specific structure, provides prevention of distal stent-graft-induced fenestration and, thereby, a stable long-term result. Using this stent-graft is effective in patients with thoracic aorta pathology undergoing the FET surgery. However, further studies are needed to determine potential advantages and disadvantages of this new hybrid graft, to obtain long-term results and accumulate experience.

Medial degeneration and atherosclerosis show discrete variance around the circumference of ascending aorta aneurysms

Medial degeneration is the most common histological finding in ascending aortic aneurysms with lesser but significant involvement by atherosclerosis. The overall extent and severity can be potentially underrated because of their uneven distribution and macroscopic inconspicuousness of medial degeneration. This study aims to compare the distribution of degenerative and atherosclerotic lesions around ascending aorta circumference, also considering aortic valve cuspidity. We evaluated 88 cases of resected ascending aortae, 25 with a tricuspid aortic valve and 63 with a malformed aortic valve, oriented by a cardiac surgeon and sent for pathological examination. We applied the consensus documents from 2015 and 2016 for microscopic evaluation of aortic specimens. The medial degeneration and atherosclerosis were graded semi-quantitatively for each aortic quadrant: convexity, anterior wall, concavity, and posterior wall. Nearly all quadrants showed at least mild medial degeneration; more severe findings of medial degeneration and atherosclerosis were in the aneurysms associated with the tricuspid valve. In the aneurysms with the tricuspid aortic valve, there was more frequent and more severe atherosclerosis at the concavity than at the anterior wall (p = .046); the frequency and severity of medial degeneration did not differ significantly. The aneurysms with a malformed aortic valve showed more severe medial degeneration at the concavity compared to the convexity (p = .011); atherosclerosis was less common and did not show any significant differences. More than half of the samples also revealed at least a one-grade (mostly one-grade) difference among the quadrants in individual cases for both atherosclerosis and medial degeneration. Extreme differences were rare except for atherosclerosis in the tricuspid group. The results revealed only slight overall differences around the aortic circumference, with concavity being the most susceptible. Still, thanks to occurring inter- and intraindividual variability, the examination of all quadrants seems meaningful not to miss the most severe changes and to underscore the findings.

Updates in aortic wall pathology

Several studies have investigated the pathogenesis of aortic wall abnormalities such as aortic dissection or aneurysm; however, the comprehensive pathological in situ event involved in the development of the disease is not understood well. The vasa vasorum form a network of capillaries or venules around the adventitia and outer media, which play an important role in the aortic wall structure and function. Impairment of their function may induce tissue hypoxia, impede the transfer of cellular nutrients, and cause aortic medial degeneration, which is considered the major predisposing factor to this aortic wall pathology. This review updates our understanding of the pathological changes in the aortic media and vasa vasorum of patients with aortic dissection and aortic aneurysm.

Synthesis of multidimensional pathophysiological process leading to type A aortic dissection: a narrative review

Objective

This review aims to synthesize the existing knowledge on the etiological process leading to type A aortic dissection (TAAD) and to clarify the relationship between mechanical, biochemical, and histopathological processes behind the aortic disease.

Background

Extensive research has previously identified several risk factors for TAAD as well as pathological mechanisms leading to TAAD. However, due to the complexity of the pathological process and limited knowledge on the relationships between distinct pathomechanisms leading to TAAD, the ability to identify the patients at high risk for TAAD has been poor.

Methods

PubMed (National Library of Medicine) database was searched for suitable literature. The most relevant articles focusing on anatomy, histopathology, physiology, and mechanics of ascending aorta and aortic diseases were reviewed.

Conclusions

Pathophysiology of the TAAD is related to biochemical and histological as well as mechanical and hemodynamic alterations leading to a degeneration of the aortic wall via inflammatory response. The degradative mechanisms of aortic wall structures and the mechanical forces, to which the wall is predisposed, are interrelated and influence one another. The relativity between the factors influencing aortic wall strength and healing capacity, and factors influencing mechanical stress on the aortic wall suggest that the risk of TAAD is not a linear but rather a dynamic phenomenon. Accounting for the dynamical property of the aortic disease in assessing the need for preventive surgical aortic reconstruction may provide a wider perspective in identifying patients at risk of TAAD and in planning preventive medical therapies.

Ascending aorta dissection in a new classification system: Clinicopathological features of 62 cases

Herein we present a single institution 5-year experience with ascending aorta dissection biopsies depicting the clinicopathological features of 62 cases. To detect microscopic abnormalities in the aortic wall beside the dissection itself, we applied a new histopathological classification scheme from the consensus documents issued by The Society for Cardiovascular Pathology and The Association for the European Cardiovascular Pathology in 2015 and 2016. The most common finding was medial degeneration (MD) - 61 cases (98.4%); atherosclerosis (AS) was found in 19 aortae (30.6%), and chronic aortitis- giant cell pattern described in one aorta (1.6%). The medial degeneration constituents included mucoid matrix accumulation, smooth muscle cells and elastic fibers abnormalities, and medial fibrosis. The consensus document application led to increased MD reporting compared to older studies and to our previous experience, probably due to assessing more subtle and focal changes such as intralamellar fibrosis, intralamellar mucoid matrix accumulation, and loss of smooth muscle cell nuclei- these changes being also the most common MD abnormalities we are reporting. We have compared the results in patients with bicuspid (n = 7; 11.3%) versus tricuspid (n = 55; 88.7%) aortic valve, suggesting no significant differences except for translamellar fibrosis, which appeared to be more severe in the bicuspid valve group (p = 0.0397). The results might imply similar histopathological findings regardless of the aortic valve cuspidity in aortic dissection. These findings are in contrast to ascending aorta dilation (aneurysm), where more severe medial degeneration changes have been described in patients with the tricuspid aortic valve.

Sirt3 Protects Against Thoracic Aortic Dissection Formation by Reducing Reactive Oxygen Species, Vascular Inflammation, and Apoptosis of Smooth Muscle Cells

Sirtuin3 (Sirt3) is a histone deacetylase involved in the regulation of many cellular processes. Sirt3 deficiency is known to increase oxidative stress. Reactive oxygen species (ROS) promote degradation of the extracellular matrix and vascular smooth muscle cell (VSMC) apoptosis. Reducing oxidative stress by Sirt3 overexpression could have therapeutic potential for limiting thoracic aortic dissection (TAD) development. We hypothesized that Sirt3 deficiency could increase the risk for TAD by decreasing ROS elimination and that Sirt3 overexpression (Sirt3^OE) could provide an alternative option for TAD treatment. Mice with TAD had significantly lower Sirt3 expression than normal subjects. Sirt3 KO mice exhibit significantly increased TAD incidence rate and increased aortic diameters. Moreover, Sirt3 overexpression reduced Ang II-induced ROS production, NF-kB activation, and apoptosis in human aortic smooth muscle cells (HASMCs). Sirt3 overexpression attenuated aneurysm formation and decreased aortic expansion. In conclusion, our data showed that Sirt3 deficiency increases susceptibility to TAD formation by attenuating anti-ROS effects and increasing VSMC apoptosis and vascular inflammation.

Vinpocetine protects against the development of experimental abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA), commonly occurring in the aged population, is a degenerative disease that dilate and weaken infrarenal aorta due to progressive degeneration of aortic wall integrity. Vinpocetine, a derivative of alkaloid vincamine, has long been used for cerebrovascular disorders and cognitive impairment in the aged population. Recent studies have indicated that vinpocetine antagonizes occlusive vascular disorders such as intimal hyperplasia and atherosclerosis. However, its role in vascular degenerative disease AAA remains unexplored. Herein, we determined the effect of vinpocetine on the formation of AAA as well as the intervention of pre-existing moderate AAA. AAA was induced by periaortic elastase application in C57BL/6J mice. Systemic vinpocetine treatment was applied daily via intraperitoneal injection. We showed that vinpocetine pre-treatment remarkably attenuated aneurysmal dilation assessed by diameter and volume. More importantly, vinpocetine also significantly suppressed the progression of pre-existing moderate AAA in a post-intervention model. Vinpocetine improved multiple cellular and molecular changes associated with AAA, such as elastin degradation, media smooth muscle cell depletion, collagen fibers remodeling and macrophage infiltration in aneurysmal tissues. Vinpocetine potently suppressed tumor necrosis factor-α-induced nuclear factor kappa-light-chain-enhancer of activated B cells activation and proinflammatory mediator expression in primary cultured macrophages in vitro, as well as in the aorta wall in vivo, suggesting vinpocetine conferred anti-AAA effect at least partially via the inhibition of inflammation. Taken together, our findings reveal a novel role of vinpocetine in AAA formation, development and progression. Given the excellent safety profile of vinpocetine, the present study suggests vinpocetine may be a novel therapeutic agent for AAA prevention and treatment.

A Systematic Histopathologic Evaluation of Type-A Aortic Dissections Implies a Uniform Multiple-Hit Causation

(1) Background: The pathophysiologic basis of an acute type A aortic dissection (TAAD) is largely unknown. In an effort to evaluate vessel wall defects, we systematically studied aortic specimens in TAAD patients. (2) Methods: Ascending aortic wall specimens (n = 58, mean age 63 years) with TAAD were collected. Autopsy tissues (n = 17, mean age 63 years) served as controls. All sections were studied histopathologically. (3) Results: Pathomorphology in TAAD showed predominantly moderate elastic fiber fragmentation/loss, elastic fiber thinning, elastic fiber degeneration, mucoid extracellular matrix accumulation, smooth muscle cell nuclei loss, and overall medial degeneration. The control group showed significantly fewer signs of those histopathological features (none-mild, p = 0.00). It was concluded that the dissection plane consistently coincides with the vasa vasorum network, and that TAAD associates with a significantly thinner intimal layer p = 0.005). (4) Conclusions: On the basis of the systematic evaluation and the consistent presence of diffuse, pre-existing medial defects, we hypothesize that TAAD relates to a developmental defect of the ascending aorta and is caused by a triple-hit mechanism that involves (I) an intimal tear; and (II) a diseased media, which allows (III) propagation of the tear towards the plane of the vasa vasorum where the dissection further progresses.

Synchrotron Radiation-based X-ray phase-contrast imaging of the aortic walls in acute aortic dissection

Objective

Synchrotron radiation-based X-ray phase-contrast tomography (XPCT) imaging is an innovative modality for the quantitative analysis of three-dimensional morphology. XPCT has been used in this study to evaluate ascending aorta specimens from patients with acute type A aortic dissection (ATAAD) and to analyze the morphologic structure of the aortic wall in patients with this condition.

Methods

Aortic specimens from 12 patients were obtained during repairs for ATAAD and were fixed with formalin. Five patients had Marfan syndrome (MFS), and seven did not. In addition, six normal aortas were obtained from autopsies. Using XPCT (effective pixel size, 12.5 μm; density resolution, 1 mg/cm³), the density of the tunica media (TM) in each sample was measured at eight points. The specimens were subsequently analyzed pathologically.

Results

The density of the TM was almost constant within each normal aorta (mean, 1.081 ± 0.001 g/cm³). The mean density was significantly lower in the ATAAD aortas without MFS (1.066 ± 0.003 g/cm³; P < .0001) and differed significantly between the intimal and adventitial sides (1.063 ± 0.003 vs 1.074 ± 0.002 g/cm³, respectively; P < .0001). The overall density of the TM was significantly higher in the ATAAD aortas with MFS than those without MFS (1.079 ± 0.008 g/cm³; P = .0003), and greater variation and markedly different distributions were observed in comparison with the normal aortas. These density variations were consistent with the pathologic findings, including the presence of cystic medial necrosis and malalignment of the elastic lamina in the ATAAD aortas with and without MFS.

Conclusions

XPCT exhibited differences in the structure of the aortic wall in aortic dissection specimens with and without MFS and in normal aortas. Medial density was homogeneous in the normal aortas, markedly varied in those with MFS, and was significantly lower and different among those without MFS. These changes may be present in the TM before the onset of aortic dissection.

Acceleration-induced acute type A aortic dissection in the sky: 10-year follow-up

Acute aortic dissection is uncommon, but can turn into a fatal disease if not managed quickly. A 49-year-old male fighter pilot presented to us after sudden excruciating chest pain during a flight at the moment of an acute spiral down action. A contrast-enhanced computed tomography angiography showed Stanford type A aortic dissection that required surgical ascending aorta and hemiarch replacement with uneventful postoperative recovery and 10-year follow-up. Here, we presented the first report of a previously healthy pilot developed acute aortic dissection in the sky. Physicians should be aware of such a case that might happen more common with rapid aviation progress.

Intramural hematoma and penetrating atherosclerotic ulcers of the aorta: uncertainties and controversies

The natural histories of intramural hematoma (IMH) and penetrating atherosclerotic ulcer (PAU) are highly variable as they may progress to aneurysm formation, rupture, or dissection, or even resolve, in the specific case of IMH. Imaging plays an increasingly important role in clinical and surgical management of IMH and PAU. In contrast to ulcer-like projections, images of intramural blood pools have not been widely reported in CT studies of patients with IMH. Understanding the imaging characteristics and the natural course of each of these entities would help clinicians and surgeons to identify patients at greatest risk for bad prognosis and may improve outcomes. This paper discusses the pathophysiology of these entities, the controversies regarding their natural history, and the prognostic factors that should be identified in CT scans.

Abnormal Ribosome Biogenesis Partly Induced p53-Dependent Aortic Medial Smooth Muscle Cell Apoptosis and Oxidative Stress

Ribosome biogenesis is a crucial biological process related to cell proliferation, redox balance, and muscle contractility. Aortic smooth muscle cells (ASMCs) show inhibition of proliferation and apoptosis, along with high levels of oxidative stress in aortic dissection (AD). Theoretically, ribosome biogenesis should be enhanced in the ASMCs at its proliferative state but suppressed during apoptosis and oxidative stress. However, the exact status and role of ribosome biogenesis in AD are unknown. We therefore analyzed the expression levels of BOP1, a component of the PeBoW complex which is crucial to ribosome biogenesis, in AD patients and a murine AD model and its influence on the ASMCs. BOP1 was downregulated in the aortic tissues of AD patients compared to healthy donors. In addition, overexpression of BOP1 in human aortic smooth muscle cells (HASMCs) inhibited apoptosis and accumulation of p53 under hypoxic conditions, while knockdown of BOP1 decreased the protein synthesis rate and motility of HASMCs. The RNA polymerase I inhibitor cx-5461 induced apoptosis, ROS production, and proliferative inhibition in the HASMCs, which was partly attenuated by p53 knockout. Furthermore, cx-5461 aggravated the severity of AD in vivo, but a p53-/- background extended the life-span and lowered AD incidence in the mice. Taken together, decreased ribosome biogenesis in ASMCs resulting in p53-dependent proliferative inhibition, oxidative stress, and apoptosis is one of the underlying mechanisms of AD.