Structural abnormalities in the non-dilated ascending aortic wall of bicuspid aortic valve patients

Pathobiology of Aortic Aneurysms and Dissections: Synthesis of Recent Investigations and Evolving Insights

The pathobiology of aortic disease is linked to aortic region: atherosclerosis for abdominal aorta, primary medial degeneration or aortitis for ascending thoracic aorta, and all causes for descending thoracic aorta and thoracoabdominal lesions. The pathogenesis of aortic dissection involves damage of the outer media from impaired perfusion from dysfunctional vasa vasorum, formation of discrete foci of disrupted vascular smooth muscle cell-elastic fiber extension-contractile units, and imbalance of radial sheer stress across the aortic wall, thereby creating an intimal tear and linear dissection. Thoracic aortic aneurysms develop from the chronic progression of medial degeneration coupled with the weakening of the remodeled adventitia, allowing for aortic dilatation. Precipitating factors include hypertension and mutations of genes regulating the vascular smooth muscle cell-elastic fiber extension-contractile units. Criteria are presented for distinguishing genetic from acquired causes of thoracic aortic aneurysms and dissections, with important implications for therapeutic and surgical decisions in the care of these patients.

Sex Differences in the Histopathology of Acute Type A Aortic Dissections

BACKGROUND

 Although sex-related differences in cardiovascular surgery outcomes have increasingly garnered attention in the past decades, knowledge about sex disparities in the pathophysiology of acute type A aortic dissections (ATAADs) remains sparse. In this study, we evaluate the histopathologic and atherosclerotic lesions in female and male ATAAD patients.

METHODS

 A total of 68 patients were studied: 51 ATAAD patients (mean age: 62.5 ± 10.8 years; 49% women) and 17 control patients (mean age: 63 ± 5.5 years; 53% women). Cardiovascular risk factors were assessed clinically. Intimal and medial histopathological features were systematically evaluated in all.

RESULTS

 Compared to the control group, all ATAAD patients showed significantly more elastic fiber pathology, mucoid extracellular matrix accumulation, smooth muscle cell nuclei loss, and overall medial degeneration (p < 0.0001). The tunica intima was significantly thinner in the ATAAD patients than in the control group (p < 0.023), with the latter exhibiting significantly more progressive atherosclerotic lesions than the former. No difference in medial vessel wall pathology was seen between female and male patients. As compared to male ATAAD patients, atherosclerotic lesions were more severe in female ATAAD patients, independent of age and the cardiovascular risk factor hypertension.

CONCLUSION

 All ATAAD patients had a significantly thinner tunica intima and significantly diseased tunica media compared to the control patients. Our results suggest that the severity of medial aortic pathology is not sex specific in ATAAD patients. Intimal differences between females and males could, however, be considered a potential risk factor for the development of an aortic dissection.

Practical Considerations of Remote Care in Thoracic Aortopathy in India

Background: Thoracic aortopathy includes conditions like aortic aneurysms and dissections, posing significant management challenges. In India, care delivery is complicated by geographic vastness, financial constraints, and healthcare resource disparities. Telemedicine and digital health technologies offer promising solutions. Methods: A comprehensive review of literature and clinical experiences was conducted to explore the implementation of remote care strategies for thoracic aortopathy in India. The review included studies from 2000 to 2023 and insights from cardiothoracic specialists. Results: Remote care benefits include improved access to specialized expertise, enhanced patient engagement, and optimized resource utilization. Telemedicine enables consultations without travel, and remote monitoring facilitates early intervention. However, challenges like technology integration, digital literacy, patient engagement, privacy concerns, and regulatory compliance need addressing. Discussion: Telemedicine offers significant advantages but requires overcoming challenges to ensure effective, secure care. Careful planning for technology integration, patient education, robust privacy measures, and supportive regulatory policies are essential. Addressing these issues can bridge the healthcare access gap and improve outcomes in India's diverse landscape.

Insights From the Histopathologic Analysis of Acquired and Genetic Thoracic Aortic Aneurysms and Dissections

OBJECTIVE

The purpose of this study was to apply contemporary consensus criteria developed by the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology to the evaluation of aortic pathology, with the expectation that the additional pathologic information may enhance the understanding and management of aortic diseases.

METHODS

A scoring system was applied to ascending aortic specimens from 42 patients with heritable thoracic aortic disease and known genetic variations and from 86 patients from a single year, including patients with known genetic variations (n = 12) and patients with sporadic disease (n = 74).

RESULTS

The various types of lesions of medial degeneration and the overall severity of medial degeneration overlapped considerably between those patients with heritable disease and those with sporadic disease; however, patients with heritable thoracic aortic disease had significantly more overall medial degeneration (P = .004) and higher levels of elastic fiber fragmentation (P = .03) and mucoid extracellular matrix accumulation (P = .04) than patients with sporadic thoracic aortic disease. Heritable thoracic aortic disease with known genetic variation was more prevalent in women than in men (27.2% vs 9.8%; P = .04), and women had more severe medial degeneration than men (P = .04). Medial degeneration scores were significantly lower for patients with bicuspid aortic valves than for patients with tricuspid aortic valves (P = .03).

CONCLUSION

The study's findings indicate considerable overlap in the pattern, extent, and severity of medial degeneration between sporadic and hereditary types of thoracic aortic disease. This finding suggests that histopathologic medial degeneration represents the final common outcome of diverse pathogenetic factors and mechanisms.

The role of transforming growth factor beta in bicuspid aortic valve aortopathy

A bicuspid aortic valve (BAV) is the most prevalent congenital cardiac deformity, which is associated with an increased risk to develop a thoracic aortic aneurysm and/or an aortic dissection as compared to persons with a tricuspid aortic valve. Due to the high prevalence of a BAV in the general population and the associated life-long increased risk for adverse vascular events, BAV disease places a considerable burden on the public health. The aim of the present review is to discuss the role of transforming growth factor beta (TGF-β) signaling in the development of the vascular wall and on how this complex signaling pathway may be involved in thoracic aortic aneurysm formation in tricuspid and BAV patients.

Evidence Accumulates: Patients with Ascending Aneurysms Are Strongly Protected from Atherosclerotic Disease

Ascending thoracic aortic aneurysms may be fatal upon rupture or dissection and remain a leading cause of death in the developed world. Understanding the pathophysiology of the development of ascending thoracic aortic aneurysms may help reduce the morbidity and mortality of this disease. In this review, we will discuss our current understanding of the protective relationship between ascending thoracic aortic aneurysms and the development of atherosclerosis, including decreased carotid intima-media thickness, low-density lipoprotein levels, coronary and aortic calcification, and incidence of myocardial infarction. We also propose several possible mechanisms driving this relationship, including matrix metalloproteinase proteins and transforming growth factor-β.

Intrinsic histological and morphological abnormalities of the pediatric thoracic aorta in bicuspid aortic valve patients are predictive for future aortopathy

BACKGROUND

Patients with a bicuspid aortic valve (BAV) have an increased risk to develop aortic complications. Many studies are pointing towards a possible embryonic explanation for the development of both a bicuspid aortic valve as well as a defective ascending aortic wall in these patients. The fetal and newborn ascending aortic wall has however scarcely been studied in bicuspid aortic valve patients. We hypothesize that early histopathological defects might already be visible in the fetal and pediatric ascending aortic wall of bicuspid aortic valve patients, indicating at an early embryonic defect.

METHODS

Non-dilated BAV ascending aortic wall samples were collected (n = 40), categorized in five age groups: premature (age range 17.5 weeks + days GA till 37.6 weeks + days GA) 2. neonate (age range 1 - 21 days) 3. infant (age range 1 month - 4 years) 4. adolescent (age range 12 years - 15 years) and 5. adult (age range 41 - 72 years). Specimen were studied for intimal and medial histopathological features.

RESULTS

The premature ascending aortic wall has a significantly thicker intimal and significantly thinner medial layer as compared to all other age categories (p < 0.05). After birth the intimal thickness decreases significantly. The medial layer increases in thickness before adulthood (p < 0.05) with an increasing number of elastic lamellae (p < 0.01) and interlamellar mucoid extracellular matrix accumulation (p < 0.0001). Intimal atherosclerosis was scarce and medial histopathological features such as overall medial degeneration, smooth muscle cell nuclei loss and elastic fiber fragmentation were not appreciated in the BAV ascending aortic wall of any age.

CONCLUSIONS

The main characteristics of a bicuspid ascending aortic wall are already present before adulthood, albeit not before birth. Considering the early manifestations of ascending aortic wall pathology in bicuspid aortic valve patients, the pediatric population should be considered while searching for markers predictive for future aortopathy.

Thoracic aortic atherosclerosis in patients with a bicuspid aortic valve; a case-control study

INTRODUCTION

Bicuspid aortic valve (BAV) patients have an increased risk to develop thoracic aortic complications. Little is known about the prevalence and severity of atherosclerosis in the BAV ascending aortic wall. This study evaluates and compares the prevalence of thoracic aortic atherosclerosis in BAV and tricuspid aortic valve (TAV) patients.

METHODS

Atherosclerosis was objectified using three diagnostic modalities in two separate BAV patient cohorts (with and without an aortic dilatation). Within the first group, atherosclerosis was graded histopathologically according to the modified AHA classification scheme proposed by Virmani et al. In the second group, the calcific load of the ascending aorta and coronary arteries, coronary angiographies and cardiovascular risk factors were studied. Patients were selected from a surgical database (treated between 2006-2020), resulting in a total of 128 inclusions.

RESULTS

Histopathology showed atherosclerotic lesions to be more prevalent and severe in all TAV as compared to all BAV patients (OR 1.49 (95%CI 1.14 - 1.94); p = 0.003). Computed tomography showed no significant differences in ascending aortic wall calcification between all BAV and all TAV patients, although a tendency of lower calcific load in favor of BAV was seen. Coronary calcification was higher in all TAV as compared to all BAV (OR 1.30 (95%CI 1.06 - 1.61); p = 0.014).

CONCLUSION

Ascending aortic atherosclerotic plaques were histologically more pronounced in TAV as compared to the BAV patients, while CT scans revealed equal amounts of calcific depositions within the ascending aortic wall. This study confirms less atherosclerosis in the ascending aortic wall and coronary arteries of BAV patients as compared to TAV patients. These results were not affected by the presence of a thoracic aortic aneurysm.

Adventitial adaptive immune cells are associated with ascending aortic dilatation in patients with a bicuspid aortic valve

Background

Bicuspid aortic valve (BAV) is associated with ascending aorta aneurysms and dissections. Presently, genetic factors and pathological flow patterns are considered responsible for aneurysm formation in BAV while the exact role of inflammatory processes remains unknown.

Methods

In order to objectify inflammation, we employ a highly sensitive, quantitative immunohistochemistry approach. Whole slides of dissected, dilated and non-dilated ascending aortas from BAV patients were quantitatively analyzed.

Results

Dilated aortas show a 4-fold increase of lymphocytes and a 25-fold increase in B lymphocytes in the adventitia compared to non-dilated aortas. Tertiary lymphoid structures with B cell follicles and helper T cell expansion were identified in dilated and dissected aortas. Dilated aortas were associated with an increase in M1-like macrophages in the aorta media, in contrast the number of M2-like macrophages did not change significantly.

Conclusion

This study finds unexpected large numbers of immune cells in dilating aortas of BAV patients. These findings raise the question whether immune cells in BAV aortopathy are innocent bystanders or contribute to the deterioration of the aortic wall.

Thoracic aortopathy in Marfan syndrome overlaps with mechanisms seen in bicuspid aortic valve disease

Background

Thoracic aortopathy is a serious complication which is more often seen in patients with Marfan syndrome (MFS) and patients with a bicuspid aortic valve (BAV) than in individuals with a tricuspid aortic valve (TAV). The identification of common pathological mechanisms leading to aortic complications in non-syndromic and syndromic diseases would significantly improve the field of personalized medicine.

Objective

This study sought to compare thoracic aortopathy between MFS, BAV, and TAV individuals.

Materials and methods

Bicuspid aortic valve (BAV; n = 36), TAV (n = 23), and MFS (n = 8) patients were included. Ascending aortic wall specimen were studied for general histologic features, apoptosis, markers of cardiovascular ageing, expression of synthetic and contractile vascular smooth muscle cells (VSMC), and fibrillin-1 expression.

Results

The MFS group showed many similarities with the dilated BAV. Both patient groups showed a thinner intima (p < 0.0005), a lower expression of contractile VSMCs (p < 0.05), more elastic fiber thinning (p < 0.001), lack of inflammation (p < 0.001), and a decreased progerin expression (p < 0.05) as compared to the TAV. Other features of cardiovascular ageing differed between the BAV and MFS. Dilated BAV patients demonstrated less medial degeneration (p < 0.0001), VSMC nuclei loss (p < 0.0001), apoptosis of the vessel wall (p < 0.03), and elastic fiber fragmentation and disorganization (p < 0.001), as compared to the MFS and dilated TAV.

Conclusion

This study showed important similarities in the pathogenesis of thoracic aortic aneurysms in BAV and MFS. These common mechanisms can be further investigated to personalize treatment strategies in non-syndromic and syndromic conditions.