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Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM–VSMC network.

A new appraisal of the management of acute aortic dissection is timely because of recent developments in diagnostic strategies (including biomarkers and imaging), endograft design, and surgical treatment, which have led to a better understanding of the epidemiology, risk factors, and molecular nature of aortic dissection. Although open surgery is the main treatment for proximal aortic repair, use of endovascular management is now established for complicated distal dissection and distal arch repair, and has recently been discussed as a pre-emptive measure to avoid late complications by inducing aortic remodelling.

Purpose Smooth muscle dysfunction syndrome (SMDS) due to heterozygous ACTA2 arginine 179 alterations is characterized by patent ductus arteriosus, vasculopathy (aneurysm and occlusive lesions), pulmonary arterial hypertension, and other complications in smooth muscle–dependent organs. We sought to define the clinical history of SMDS to develop recommendations for evaluation and management. Methods Medical records of 33 patients with SMDS (median age 12 years) were abstracted and analyzed. Results All patients had congenital mydriasis and related pupillary abnormalities at birth and presented in infancy with a patent ductus arteriosus or aortopulmonary window. Patients had cerebrovascular disease characterized by small vessel disease (hyperintense periventricular white matter lesions; 95%), intracranial artery stenosis (77%), ischemic strokes (27%), and seizures (18%). Twelve (36%) patients had thoracic aortic aneurysm repair or dissection at median age of 14 years and aortic disease was fully penetrant by the age of 25 years. Three (9%) patients had axillary artery aneurysms complicated by thromboembolic episodes. Nine patients died between the ages of 0.5 and 32 years due to aortic, pulmonary, or stroke complications, or unknown causes. Conclusion Based on these data, recommendations are provided for the surveillance and management of SMDS to help prevent early-onset life-threatening complications.

Objective This study aims to investigate the clinical manifestations, operative techniques, and outcomes of patients who undergo open repair after thoracic endovascular aortic repair (TEVAR). Methods From January 2010 to June 2022, 113 consecutive type A aortic dissection (TAAD) patients underwent secondary open operation after TEVAR at our institution, and the median interval from primary intervention to open surgery was 12 (1.9–48.0) months. We divided the patients into two groups (RTAD (retrograde type A dissection) group, N  = 56; PNAD (proximal new aortic dissection) group, N  = 57) according to their anatomical features. Survival analysis during the follow-up was evaluated using a Kaplan–Meier survival curve and a log-rank test. Results The 30-day mortality was 6.2% (7/113), the median follow-up period was 31.7 (IQR 14.7–65.6) months, and the overall survival at 1 year, 5 years, and 10 years was 88.5%, 88.5%, and 87.6%, respectively. Fourteen deaths occurred during the follow-up, but there were no late aorta-related deaths. Three patients underwent total thoracoabdominal aortic replacement 1 year after a second open operation. The RTAD group had a smaller ascending aorta size (42.5 ± 7.7 mm vs 48.4 ± 11.4 mm; P  < .01) and a closer proximal landing zone ( P  < .01) compared to the PNAD group. However, there were no differences in survival between the two groups. Conclusions TAAD can present as an early or a late complication after TEVAR due to stent-grafting-related issues or disease progression. Open operation can be performed to treat TAAD, and this has acceptable early and mid-term outcomes. Follow-up should become mandatory for patients after TEVAR because these patients are at increased risk for TAAD.

Heritable thoracic aortic aneurysms and dissections (hTAAD) are life-threatening complications of well-known syndromic diseases or underdiagnosed nonsyndromic heritable forms (nshTAAD). Both have an autosomal dominant transmission and are genetically heterogeneous. Our objective was to describe the relevance of molecular diagnosis in these patients and the contribution of each gene in nshTAAD. Two hundred twenty-six consecutive nshTAAD probands, either young (<45 years) sporadic or familial cases were included. A next-generation sequencing capture panel comprising 23 known disease-causing genes was performed. Class 4 or 5 variants were identified in 18% of the nshTAAD probands, while class 3 variants were found in 10% of them. The yield in familial cases was greater than in sporadic cases. SMAD3 and FBN1 genes were the major disease-causing genes. Unexpectedly, no premature termination codon variant was identified in the FBN1 gene. Furthermore, we report for the first time that aortic dissection or surgery occurred significantly more often and earlier in probands with a class 4 or 5 pathogenic variant. This study indicates that genetic screening using NGS is efficient in young and familial nshTAAD. The presence of a pathogenic variant has a possible predictive value, which needs to be further investigated because it may influence care.

Ascending thoracic aortic aneurysm (ATAA) pathogenesis varies with aortic valve morphology, yet regional heterogeneity between inner curvature (IC) and outer curvature (OC) remains incompletely characterized. We hypothesized that regional differences between the outer and inner curvature of the ascending aorta are valve-morphology dependent and reflect distinct remodeling mechanisms in bicuspid versus tricuspid aortic valve-associated aortopathy. Ascending aortic tissue from 155 patients (69 tricuspid aortic valve [TAV], 68 bicuspid aortic valve [BAV], 18 non-aneurysmal heart transplantation [HTx] controls) underwent uniaxial tensile testing (n = 66), histological analysis, hydroxyproline assay, and reverse transcription quantitative PCR (RT-qPCR) for collagen (COL1A1, COL3A1, COL4A1, COL5A1, COL11A1) and elastin (ELN) genes. The OC was thinner than the IC in both TAV and BAV (p < 0.001), with no regional differences in HTx. TAV demonstrated increased OC stiffness (E-modulus 0.60 ± 0.31 vs. 0.43 ± 0.24 MPa, p = 0.004) with reduced failure strain (p = 0.013). BAV showed preserved stiffness but reduced OC extensibility (ε_max 56.5 ± 15.1% vs. 72.4 ± 21.7%, p < 0.001). BAV exhibited elevated OC collagen content (hydroxyproline OC/IC ratio 1.42, p = 0.048), whereas TAV showed reduced OC elastin area (p < 0.01). All collagen genes were upregulated at the OC in both TAV (all p < 0.001) and BAV (all p < 0.05), with COL11A1 showing the highest fold change (3.4-fold in TAV). ELN was reduced at the OC in TAV (p < 0.001) but unchanged in BAV. ATAAs exhibit distinct valve-dependent regional heterogeneities. The discordance between collagen gene expression and protein content suggests valve-specific differences in collagen regulation. These findings support distinct pathomechanisms and highlight the limitations of diameter-based risk stratification, motivating further investigation of regional wall assessment as a complement to current size criteria for surgical decision-making.

Genetic factors are fundamental in the etiology of thoracic aortic aneurysm and dissection (TAAD), but the genetic cause is detected in only about 30% of cases. To define unreported TAAD-associated sequence variants, exome and gene panel sequencing was performed in 323 patients. We identified heterozygous CDKL1 variants [c.427T>C p.(Cys143Arg), c.617C>T p.(Ser206Leu), and c.404C>T p.(Thr135Met)] in 6 patients from 3 families with TAAD spectrum disorders. CDKL1 encodes a protein kinase involved in ciliary biology. Amino acid substitutions were predicted to affect CDKL1 catalytic activity or protein binding properties. CDKL1 was expressed in vascular smooth muscle cells in normal and diseased human aortic wall tissue. Cdkl1 knockdown and transient knockout in zebrafish resulted in intersomitic vessel (ISV) malformations and aortic dilation. Coinjection of human CDKL1 wild-type RNA, but not CDKL1 Cys143Arg and CDKL1 Ser206Leu RNA, rescued ISV malformations. All variants affected CDKL1 kinase function and profiling data, and altered protein-protein binding properties, particularly with ciliary transport molecules. Expression of CDKL1 variants in heterologous cells interfered with cilia formation and length, CDKL1 localization, and p38 MAPK and Vegf signaling. Our data suggest a role of CDKL1 variants in the pathogenesis of TAAD spectrum disorders. The association between primary cilia dysregulation and TAAD expands our knowledge of the underlying molecular pathophysiology.

Thoracic aortic aneurysm and dissection (TAAD) affects many patients globally and has high mortality rates if undetected. Once thought to be solely a degenerative disease that afflicted the aorta due to high pressure and biomechanical stress, extensive investigation of the heritability and natural history of TAAD has shown a clear genetic basis for the disease. Here, we review both the cellular mechanisms and clinical manifestations of syndromic and non-syndromic TAAD. We particularly focus on genes that have been linked to dissection at diameters <5.0 cm, the current lower bound for surgical intervention. Genetic screening tests to identify patients with TAAD associated mutations that place them at high risk for dissection are also discussed.

Thoracic aortic aneurysms (TAA) are permanent and localized dilations of the aorta that predispose patients to a life-threatening risk of aortic dissection or rupture. The identification of pathogenic variants that cause hereditary forms of TAA has delineated fundamental molecular processes required to maintain aortic homeostasis. Vascular smooth muscle cells (VSMCs) elaborate and remodel the extracellular matrix (ECM) in response to mechanical and biochemical cues from their environment. Causal variants for hereditary forms of aneurysm compromise the function of gene products involved in the transmission or interpretation of these signals, initiating processes that eventually lead to degeneration and mechanical failure of the vessel. These include mutations that interfere with transduction of stimuli from the matrix to the actin–myosin cytoskeleton through integrins, and those that impair signaling pathways activated by transforming growth factor-β (TGF-β). In this review, we summarize the features of the healthy aortic wall, the major pathways involved in the modulation of VSMC phenotypes, and the basic molecular functions impaired by TAA-associated mutations. We also discuss how the heterogeneity and balance of adaptive and maladaptive responses to the initial genetic insult might contribute to disease.

Background In patients with bicuspid valve (BAV), ascending aorta (AAo) dilatation may be caused by altered flow patterns and wall shear stress (WSS). These differences may explain different aortic dilatation morphotypes. Using 4D-flow cardiovascular magnetic resonance (CMR), we aimed to analyze differences in flow patterns and regional axial and circumferential WSS maps between BAV phenotypes and their correlation with ascending aorta dilatation morphotype. Methods One hundred and one BAV patients (aortic diameter ≤ 45 mm, no severe valvular disease) and 20 healthy subjects were studied by 4D-flow CMR. Peak velocity, flow jet angle, flow displacement, in-plane rotational flow (IRF) and systolic flow reversal ratio (SFRR) were assessed at different levels of the AAo. Peak-systolic axial and circumferential regional WSS maps were also estimated. Unadjusted and multivariable adjusted linear regression analyses were used to identify independent correlates of aortic root or ascending dilatation. Age, sex, valve morphotype, body surface area, flow derived variables and WSS components were included in the multivariable models. Results The AAo was non-dilated in 24 BAV patients and dilated in 77 (root morphotype in 11 and ascending in 66). BAV phenotype was right-left (RL-) in 78 patients and right-non-coronary (RN-) in 23. Both BAV phenotypes presented different outflow jet direction and velocity profiles that matched the location of maximum systolic axial WSS. RL-BAV velocity profiles and maximum axial WSS were homogeneously distributed right-anteriorly, however, RN-BAV showed higher variable profiles with a main proximal-posterior distribution shifting anteriorly at mid-distal AAo. Compared to controls, BAV patients presented similar WSS magnitude at proximal, mid and distal AAo ( p  = 0.764, 0.516 and 0.053, respectively) but lower axial and higher circumferential WSS components ( p  < 0.001 for both, at all aortic levels). Among BAV patients, RN-BAV presented higher IRF at all levels ( p  = 0.024 proximal, 0.046 mid and 0.002 distal AAo) and higher circumferential WSS at mid and distal AAo ( p  = 0.038 and 0.046, respectively) than RL-BAV. However, axial WSS was higher in RL-BAV compared to RN-BAV at proximal and mid AAo ( p  = 0.046, 0.019, respectively). Displacement and axial WSS were independently associated with the root-morphotype, and circumferential WSS and SFRR with the ascending-morphotype. Conclusions Different BAV-phenotypes present different flow patterns with an anterior distribution in RL-BAV, whereas, RN-BAV patients present a predominant posterior outflow jet at the sinotubular junction that shifts to anterior or right anterior in mid and distal AAo. Thus, RL-BAV patients present a higher axial WSS at the aortic root while RN-BAV present a higher circumferential WSS in mid and distal AAo. These results may explain different AAo dilatation morphotypes in the BAV population.