Aortic Dilatation Research Articles

High-Throughput Genomics Identify Novel FBN1/2 Variants in Severe Neonatal Marfan Syndrome and Congenital Heart Defects.

Fibrillin-1 and fibrillin-2, encoded by FBN1 and FBN2, respectively, play significant roles in elastic fiber assembly, with pathogenic variants causing a diverse group of connective tissue disorders such as Marfan syndrome (MFS) and congenital contractural arachnodactyly (CCD). Different genomic variations may lead to heterogeneous phenotypic features and functional consequences. Recent high-throughput sequencing modalities have allowed detection of novel variants that may guide the care for patients and inform the genetic counseling for their families. We performed clinical phenotyping for two newborn infants with complex congenital heart defects. For genetic investigations, we employed next-generation sequencing strategies including whole-genome Single-Nucleotide Polymorphism (SNP) microarray for infant A with valvular insufficiency, aortic sinus dilatation, hydronephrosis, and dysmorphic features, and Trio whole-exome sequencing (WES) for infant B with dextro-transposition of the great arteries (D-TGA) and both parents. Infant A is a term male with neonatal marfanoid features, left-sided hydronephrosis, and complex congenital heart defects including tricuspid regurgitation, aortic sinus dilatation, patent foramen ovale, patent ductus arteriosus, mitral regurgitation, tricuspid regurgitation, aortic regurgitation, and pulmonary sinus dilatation. He developed severe persistent pulmonary hypertension and worsening acute hypercapnic hypoxemic respiratory failure, and subsequently expired on day of life (DOL) 10 after compassionate extubation. Cytogenomic whole-genome SNP microarray analysis revealed a deletion within the FBN1 gene spanning exons 7-30, which overlapped with the exon deletion hotspot region associated with neonatal Marfan syndrome. Infant B is a term male prenatally diagnosed with isolated D-TGA. He required balloon atrial septostomy on DOL 0 and subsequent atrial switch operation, atrial septal defect repair, and patent ductus arteriosus ligation on DOL 5. Trio-WES revealed compound heterozygous c.518C>T and c.8230T>G variants in the FBN2 gene. Zygosity analysis confirmed each of the variants was inherited from one of the parents who were healthy heterozygous carriers. Since his cardiac repair at birth, he has been growing and developing well without any further hospitalization. Our study highlights novel FBN1/FBN2 variants and signifies the phenotype-genotype association in two infants affected with complex congenital heart defects with and without dysmorphic features. These findings speak to the importance of next-generation high-throughput genomics for novel variant detection and the phenotypic variability associated with FBN1/FBN2 variants, particularly in the neonatal period, which may significantly impact clinical care and family counseling.

Wall shear stress measured with 4D flow CMR correlates with biomarkers of inflammation and collagen synthesis in mild-to-moderate ascending aortic dilation and tricuspid aortic valves.

Understanding the mechanisms underlying ascending aortic dilation is imperative for refined risk stratification of these patients, particularly among incidentally identified patients, most commonly presenting with tricuspid valves. The aim of this study was to explore associations between ascending aortic haemodynamics, assessed using four-dimensional flow cardiovascular magnetic resonance imaging (4D flow CMR), and circulating biomarkers in aortic dilation. Forty-seven cases with aortic dilation (diameter ≥ 40 mm) and 50 sex-and age-matched controls (diameter < 40 mm), all with tricuspid aortic valves, underwent 4D flow CMR and venous blood sampling. Associations between flow displacement, wall shear stress (WSS), and oscillatory shear index in the ascending aorta derived from 4D flow CMR, and biomarkers including interleukin-6, collagen type I α1 chain, metalloproteinases (MMPs), and inhibitors of MMPs derived from blood plasma, were investigated. Cases with dilation exhibited lower peak systolic WSS, higher flow displacement, and higher mean oscillatory shear index compared with controls without dilation. No significant differences in biomarkers were observed between the groups. Correlations between haemodynamics and biomarkers were observed, particularly between maximum time-averaged WSS and interleukin-6 (r = 0.539, P < 0.001), and maximum oscillatory shear index and collagen type I α1 chain (r = -0.575, P < 0.001 in cases). Significant associations were discovered between 4D flow CMR derived whole-cardiac cycle WSS and circulating biomarkers representing inflammation and collagen synthesis, suggesting an intricate interplay between haemodynamics and the processes of inflammation and collagen synthesis in patients with early aortic dilation and tricuspid aortic valves.

Unravelling supravalvular aortic stenosis in a young patient: look beyond the valve.

A 16-year-old adolescent girl was referred to our tertiary care center for management of a failed aortic valve balloon dilatation procedure for congenital valvular aortic stenosis. The medical records revealed a residual peak-to-peak gradient of 80 mm Hg after 2 dilations with 16 x 6-mm Tyshak balloon (NuMed Inc.).

Mitral annular disjunction and its progression during childhood in Marfan syndrome.

Data on mitral annular disjunction (MAD) in children with Marfan syndrome (MFS) are sparse. To investigate the diagnostic yield of MAD by echocardiography and cardiac magnetic resonance imaging (CMR), its prevalence and progression during childhood. We included patients <21 years old with MFS, defined by 2010 Ghent criteria and a pathogenic FBN1 variant or ectopia lentis. Two readers measured systolic separation between the mitral valve (MV) posterior hinge point and left ventricular (LV) myocardium on initial and subsequent imaging. MAD was defined as MV-LV separation ≥2 mm, MV prolapse (MVP) as atrial displacement ≥2 mm. Kappa coefficients evaluated echocardiogram-CMR agreement. Bland-Altman and intraclass correlation coefficients (ICCs) assessed inter-rater and inter-modality reliability. Univariable mixed-effects linear regression was used to evaluate longitudinal changes of MAD. MAD was detected in 60% (110/185) eligible patients. MVP was present in 48% (53/110) of MAD and MAD in 90% (53/59) of MVP. MAD detection by CMR and echocardiography had 96% overall agreement (Kappa = 0.89, P < 0.001) and a 0.32 mm estimate bias (95% CI 0.00, 0.65). ICC by echocardiography, CMR, and between modalities were 0.97 (95% CI 0.93, 0.98), 0.92 (95% CI 0.79, 0.97), and 0.91 (95% CI 0.85, 0.94), respectively. MAD was associated with aortic root dilation (P < 0.001). MAD was found in children of all ages, increased +0.18 mm/year (95% CI +0.14, +0.22) during a median duration of 5.5 years (IQR 3.1, 7.5 years). MAD indexed by height yielded a constant value +0.0002 mm/m/year (95% CI -0.0002, +0.0005 mm/m/year). MAD was common in pediatric MFS and was associated with aortic root dilation. MAD detection by echocardiography and CMR was highly reliable, suggesting that routine assessment in MFS is feasible. MAD was present in neonates and progressed over time but remained constant when indexing by height. Further studies are needed to evaluate MAD as a biomarker for clinical outcomes in pediatric MFS.

A Geant Abdominal Aortic Aneurysm Who Hides Others: A Case Report

A 67-year-old man with a history of MCA (middle cerebral artery) aneurysm, smoking, and arterial hypertension, presented to the emergency department with abdominal pain and a pulsatile mass. The patient's vital signs were within normal ranges. On physical examination, the patient was mildly discomforted due to abdominal pain. His abdomen was soft, with tenderness in the right lower quadrant, and a pulsatile mass was present. A CT scan of the abdomen and pelvis with intravenous iodinated contrast revealed an aneurysmal dilatation of the abdominal aorta measuring 7 cm in diameter, beginning inferior to the level of the renal arteries and continuing to the iliac bifurcation with thrombosis of the right common iliac artery extending its branches. Associated with an aneurysmal dilatation of the celiac trunk and the splenic artery. There was extensive mural thrombus, a patent lumen, and no evidence of frank rupture.

Assessment of aortic dilatation in Chinese children and adolescents with Turner syndrome: a single center experience

BackgroundPatients with Turner syndrome (TS) face an increased risk of developing aortic dilatation (AD), but diagnosing AD in children presents greater complexity compared to adults. This study aimed to investigate the application of various assessment indicators of AD in Chinese children and adolescents with TS.MethodsThis study included TS patients admitted to Shenzhen Children’s Hospital from 2017 to 2022. Cardiovascular lesions were diagnosed by experienced radiologists. Patients without structural heart disease were divided into different body surface area groups, then the Chinese TS population Z-score (CHTSZ-score) of the ascending aorta was calculated and compared with other indicators such as aortic size index (ASI), ratio of the ascending to descending aortic diameter (A/D ratio), and TSZ-score (Quezada’s method).ResultsA total of 115 TS patients were included, with an average age of 10.0 ± 3.7 years. The incidences of the three most serious cardiovascular complications were 9.6% (AD), 10.4% (coarctation of the aorta, CoA), and 7.0% (bicuspid aortic valve, BAV), respectively. The proportion of developing AD in TS patients aged ≥ 10 years was higher than that in those < 10 years old (16.6% vs. 1.8%, P = 0.009), and the proportion of patients with CoA or BAV who additionally exhibited AD was higher than those without these conditions (31.6% vs. 5.2%, P < 0.001). The ASI, A/D ratio, TSZ-score, and CHTSZ-score of the 11 patients with AD were 2.27 ± 0.40 cm/m2, 1.90 ± 0.37, 1.28 ± 1.08, and 3.07 ± 2.20, respectively. Among the AD patients, only 3 cases had a TSZ-score ≥ 2, and 2 cases had a TSZ-score ≥ 1. However, based on the assessment using the CHTSZ-score, 6 patients scored ≥ 2, and 5 patients scored ≥ 1. In contrast, the TSZ-score generally underestimated the aortic Z-scores in Chinese children with TS compared to the CHTSZ-score.ConclusionsThe applicability of ASI and A/D ratio to children with TS is questionable, and racial differences can affect the assessment of TSZ-score in the Chinese population. Therefore, establishing the CHTSZ-score specifically tailored for Chinese children and adolescents is of paramount importance.

Effect of beta-blockers and angiotensin receptor blockers in reducing the aortic growth rate in children with bicuspid aortic valve-related aortopathy

AimsThe aim of this study is to evaluate the effect of beta-blockers and angiotensin receptor blockers in reducing the aortic growth rate in children with bicuspid aortic valve (BAV)-related aortopathy and ascending phenotype. MethodsConsecutive paediatric patients (≤16 years) with BAV and ascending aorta (AsAo) dilation (z-score > 3) were enrolled in this observational retrospective cohort study. Patients receiving prophylactic treatment with either atenolol (0.5 to 1.0 mg/kg/daily) or losartan (0.7 to 1.4 mg/kg/daily) were compared with those who did not receive medical prophylaxis (control group). The primary outcome of interest was the annual rate of change in maximal AsAo diameter z-score in the treatment and control groups. ResultsFrom a cohort of 1005 patients, 120 (mean age 11.3 ± 4.5 years, 82% males) fulfilled the inclusion criteria and were included in the study. Patients in the treatment and control group had similar age, sex, family history of BAV, BAV morphology, and baseline AsAo diameter. During a median follow-up of 7.1 years (interquartile range 3.8–10.2), no differences were observed in the annual growth rate of aortic diameter z-score between patients on treatment and controls. The prevalence of aortic diameter progression was similar in the treatment and control groups, and treatment with atenolol or losartan was not associated with a lower rate of aortic disease progression. ConclusionsThe findings revealed no significant difference in the annual aortic growth rate between treated and untreated patients. Larger cohort studies or, ideally, randomized clinical controlled trials are needed to validate these findings.

Investigation of Strategies to Block Downstream Effectors of AT1R-Mediated Signalling to Prevent Aneurysm Formation in Marfan Syndrome.

Cardiovascular outcome in Marfan syndrome (MFS) patients most prominently depends on aortic aneurysm progression with subsequent aortic dissection. Angiotensin II receptor blockers (ARBs) prevent aneurysm formation in MFS mouse models. In patients, ARBs only slow down aortic dilation. Downstream signalling from the angiotensin II type 1 receptor (AT1R) is mediated by G proteins and β-arrestin recruitment. AT1R also interacts with the monocyte chemoattractant protein-1 (MCP-1) receptor, resulting in inflammation. In this study, we explore the targeting of β-arrestin signalling in MFS mice by administering TRV027. Furthermore, because high doses of the ARB losartan, which has been proven beneficial in MFS, cannot be achieved in humans, we investigate a potential additive effect by combining lower concentrations of losartan (25 mg/kg/day and 5 mg/kg/day) with barbadin, a β-arrestin blocker, and DMX20, a C-C chemokine receptor type 2 (CCR2) blocker. A high dose of losartan (50 mg/kg/day) slowed down aneurysm progression compared to untreated MFS mice (1.73 ± 0.12 vs. 1.96 ± 0.08 mm, p = 0.0033). TRV027, the combination of barbadin with losartan (25 mg/kg/day), and DMX-200 (90 mg/kg/day) with a low dose of losartan (5 mg/kg/day) did not show a significant beneficial effect. Our results confirm that while losartan effectively halts aneurysm formation in Fbn1C1041G/+ MFS mice, neither TRV027 alone nor any of the other compounds combined with lower doses of losartan demonstrate a notable impact on aneurysm advancement. It appears that complete blockade of AT1R function, achieved by administrating a high dosage of losartan, may be necessary for inhibiting aneurysm progression in MFS.

COQ7 defect causes prenatal onset of mitochondrial CoQ10 deficiency with cardiomyopathy and gastrointestinal obstruction

COQ7 pathogenetic variants cause primary CoQ10 deficiency and a clinical phenotype of encephalopathy, peripheral neuropathy, or multisystemic disorder. Early diagnosis is essential for promptly starting CoQ10 supplementation. Here, we report novel compound heterozygous variants in the COQ7 gene responsible for a prenatal onset (20 weeks of gestation) of hypertrophic cardiomyopathy and intestinal dysmotility in a Bangladesh consanguineous family with two affected siblings. The main clinical findings were dysmorphisms, recurrent intestinal occlusions that required ileostomy, left ventricular non-compaction cardiomyopathy, ascending aorta dilation, arterial hypertension, renal dysfunction, diffuse skin desquamation, axial hypotonia, neurodevelopmental delay, and growth retardation. Exome sequencing revealed compound heterozygous rare variants in the COQ7 gene, c.613_617delGCCGGinsCAT (p.Ala205HisfsTer48) and c.403A>G (p.Met135Val). In silico analysis and functional in vitro studies confirmed the pathogenicity of the variants responsible for abolished activities of complexes I + III and II + III in muscle homogenate, severe decrease of CoQ10 levels, and reduced basal and maximal respiration in patients’ fibroblasts. The first proband deceased at 14 months of age, whereas supplementation with a high dose of CoQ10 (30 mg/kg/day) since the first days of life modified the clinical course in the second child, showing a recovery of milestones acquirement at the last follow-up (18 months of age). Our study expands the clinical spectrum of primary CoQ10 deficiency due to COQ7 gene defects and highlights the essential role of multidisciplinary and combined approaches for a timely diagnosis.

Progression of the ascending aorta diameter after surgical or transcatheter bicuspid aortic valve replacement.

Ascending aorta (AA) dilatation in patients with bicuspid aortic valve (AV) is related both to genetic and haemodynamic factors. The aim of this study is to compare late progression of AA dilatation in bicuspid AV patients undergoing surgical aortic valve replacement (SAVR) versus transcatheter aortic valve implantation (TAVI). Data of 189 consecutive patients who underwent AV replacement for severe bicuspid AV stenosis were prospectively collected. Patients who underwent SAVR were compared to patients who underwent TAVI. Indication to the procedure was validated by the institutional Heart Team. Aortic diameters were evaluated by transthoracic echocardiogram. Differences between preoperative and long-term follow-up AA diameters were compared in the 2 groups. Between January 2015 and December 2021, 143 (76%) patients underwent SAVR and 46 (24%) patients underwent TAVI. At 4.6 (standard deviation 1.7) years follow-up, patients in the TAVI group showed significantly lower survival (P = 0.00013) and event-free survival (P < 0.0001). AA diameter progression was lower in surgical compared to transcatheter patients, 0.95 (0.60, 1.30) vs 1.65 (0.67, 2.63) mm, P = 0.02. AA diameter progression indexed for body surface area and height was lower in the surgical group: 0.72 (0.38, 1.05) vs 1.05 (0.39, 1.71) mm/m2, P = 0.02, and 0.59 (0.36, 0.81) vs 1.11 (0.44, 1.78) mm/m, P = 0.001, respectively. At multivariable linear regression analysis transcatheter procedure, baseline aortic diameter and paravalvular leak were significantly associated with increased postoperative AA dilatation. Bicuspid AV patients who underwent SAVR, showed significantly less long-term AA diameter progression than patients who underwent transcatheter procedure.

Abstract 2128: Hepcidin Loss Demonstrates Sex Dependent Differences In Aortic Aneurysm Size

Background: Studies suggest circulating iron levels play a role in the pathophysiology of abdominal aortic aneurysms (AAAs). Low iron levels lead to medial degeneration and VSMC dysfunction while elevated iron levels promote oxidative stress. Hepcidin is a major iron regulatory hormone that binds ferroportin to reduce serum iron levels, and its removal in VSMCs has been shown to exacerbate AAAs; however, the role of sex in this mechanism remains understudied. The goal of the current study is to investigate the potential role of sex in iron metabolism in AAAs. Methods: Male and female C57BL/6 wild-type (WT/WT), heterozygous hepcidin knock-out (WT/KO) and hepcidin KO (KO/KO) underwent peri-adventitial application of porcine pancreatic elastase on the infrarenal aorta (n=10-19/group). At day 14, the aortas were measured using video micrometry and harvested for immunohistochemistry. In separate studies, male and female hepcidin WT/WT and KO/KO underwent elastase application and systemic b-aminopropionitrile (BAPN, 0.02%) administration and were harvested at 28 days. Finally, male and female LysM Cre Ferroportin flx/flx mice and their controls underwent elastase application and harvested at 14 days (n=5-10/group). Results: Hepcidin WT/KO and KO/KO male mice had dose dependent protection of aneurysm formation compared with controls (WT/WT: 145.5±33.8% vs WT/KO: 110.7±34.8% vs KO/KO: 53.7±13.7%, p=0.0001 by ANOVA). Female Hepcidin WT/KO and KO/KO mice exhibited increased AAA size compared with their controls (KO/KO: 119.0±23.5% vs WT/KO: 101.6 ±28.6% vs WT/WT: 71.2±22.0%, p =.0011 by ANOVA). In the elastase + BAPN model, Hepcidin KO/KO male mice had less aortic dilation compared to controls (KO/KO: 196.0 ±31.9% vs WT/WT: 476.8±82.2%, p =.0002 by Mann-Whitney) while female KO/KO mice exhibited greater aortic dilation (WT/WT: 186.7±26.0% vs. KO/KO: 406.9±62.2%, p=0.006). Male LysM Cre Ferroportin flx/flx mice had decreased aortic dilation (WT/WT: 132.5±19.3% vs flx/flx: 53.5±7.8%, p=0.001). Conclusion: Elimination of hepcidin in AAA formation exhibited protective effects in male and deleterious effects in female mice. This data suggests targeting of hepcidin using drug-based therapies could have gender-specific clinical implications.

Abstract 2009: Computational Modeling Of Long-term Aortic Root Dilatation Following TEVAR Of Type B Aortic Dissection

Objectives: The long-term sequalae of thoracic endovascular aortic repair (TEVAR) are poorly understood. While several failure modes have been identified, the hemodynamic impact of TEVAR in the proximal native ascending aorta has yet to be fully appreciated. This study applies computational modeling tools to investigate a case of long-term aortic root dilatation following TEVAR for acute type B aortic dissection (TBAD). Methods: We investigate a patient who presented with heart failure 4.5 years after initially successful TEVAR. Cross-sectional aortic root diameter was measured in a pre-operative scan and 57 months post-TEVAR. Three-dimensional localized surface dilatation was calculated using pre-operative and post-operative segmentations, followed by a non-rigid surface mapping method of calculating area change in corresponding regions. The hemodynamic impact of TEVAR on the proximal aorta was analyzed with a computational fluid dynamics (CFD) simulation of the post-operative patient geometry. Results: Aortic root diameter increased from 39.2 mm pre-op to 47.1 mm (+ 20.1%) postop and 34.9 mm preop to 40.8 mm (+ 16.9%) postop on axial and coronal images respectively. The three-dimensional area mapping between pre and post-op scans demonstrates a maximum 14% area increase near the aortic root. The CFD simulations show increased velocity and static pressure in the ascending aorta near the aortic root region. Conclusions: Three different computational approaches demonstrate long-term changes in ascending aortic morphology following TEVAR. Computed tomography measurements demonstrate significant aortic root dilatation, and three-dimensional surface mapping shows increasing area in the proximal ascending aorta. The CFD results emphasize localization of increased velocity and stress in the same region. These observations point to potential avenues for further mechanistic investigation.

Abstract 2022: AlphaV Integrins Inhibition Downregulates Pro-fibrotic Events In Human Aortic Smooth Muscle Cells And Limits Thoracic Aortic Aneurysm Progression In Marfan Mice

Aortic dilation can often lead to lethal events, such as aortic dissection and/or vessel rupture. The aneurysms occurring in the thoracic aortic trait (TAA) may depend on comorbidities, such as hypertension, or on genetically determined conditions, such as Marfan syndrome (MFS). To date, the surgical replacement of aorta represents the most effective therapeutic approach in all TAA patients, since an etiologic pharmacological treatment is still lacking. Integrin receptors are key players in cellular mechanotransduction responses and the role of integrins containing αV subunit have been described as responsible for pro-fibrotic molecular events. Recently, it has been reported the effectiveness of a pan αV integrin inhibitor ( i.e. , GLPG0187) in limiting the TAA progression in MFS in vivo model. However, the specific αV integrin subgroup directly involved in this detrimental process is yet not known. We evaluated the effectiveness of the specific αVβ3 and αVβ5 integrin inhibitor cilengitide in downregulating pro-fibrotic in vitro events on MFS patients’ vascular smooth muscle cells (MFS-VSMC), and in limiting in vivo thoracic aortic dilation on a MFS mice model. By comparison with healthy control (HC)-VSMC, MFS-VSMC showed higher levels of αVβ3 and αVβ5 integrins as well as pro-fibrotic collagen I. When compared with GLPG0187, the cilengitide-mediated in vitro inhibition of these integrins determined a more effective downregulation of TGF-β downstream pathways (SMAD2/3 and ERK1/2) as well as a statistical tempered expression of pro-fibrotic mechanotransduction mediators, such as RhoA GTPase. The 2D-echocardiographic results on MFS mice (Fbn1 C1039G/+ ) treated with cilengitide confirmed the greater effectiveness of this drug in limiting the TAA progression, not only in comparison with vehicle but also with the broad pan αV integrin inhibitor GLPG0187. Altogether, our results improve the know-how on αV integrin involvement in MFS-TAA scenario, unveiling the specific detrimental role of αVβ3 and αVβ5 in this pathological context. The selective inhibition of these integrins exerted by cilengitide highlights the role of this compound as a potential and more targeted tool for future therapeutic approaches to limit TAA progression in MFS patients.

Abstract 2021: 18 F-Sodium Fluoride Positron Emission Tomography To Assess Thoracic Aortopathy In Bicuspid Aortic Valve Disease

Background: Bicuspid aortic valve is associated with thoracic aortopathy with many patients suffering aortic dissection below the aortic diameter threshold for prophylactic aortic replacement surgery. In aortopathy, the aortic wall media initially undergoes increasing microcalcification due to elastin fibre fragmentation but with disease progression, elastin fibre degradation leads to loss of aortic microcalcification. 18 F-Sodium fluoride positron emission tomography (PET) is a non-invasive method of detecting arterial microcalcification that has been successfully used in cardiovascular disease risk stratification. Aims: To determine if aortic 18 F-sodium fluoride imaging can identify aortopathy and predict subsequent disease progression in patients with bicuspid aortic valve disease. Methods: In this prospective cohort study, 77 patients with bicuspid aortic valve from clinical sites across Scotland and 18 healthy volunteers, underwent 18 F-sodium fluoride PET-computed tomography (PET-CT) followed immediately by PET-magnetic resonance imaging (PET-MRI). Maximum standardised uptake values (SUVmax) were determined in the ascending aorta. Aortic diameters were measured in aortic axial CINE MRI sequences. Patients were followed-up at 24 months with a further PET-MRI. Annualised change in aortic size index (mm/m 2 /year) and annualised change in SUVmax stratified in tertiles were calculated. Results: Patients with bicuspid aortic valve disease had higher SUVmax than control subjects, especially in those with aortic dilatation. Baseline SUVmax was associated with annualised aortic expansion rate independent of baseline aortic size (β=0.45, p=0.001). Patients in tertile 1 (loss of SUVmax over time) exhibited greater aortic growth (0.60±0.50 mm/m 2 /year) than those with stable SUVmax (tertile 2, 0.26±0.36 mm/m 2 /year) or increasing SUVmax (tertile 3, 0.24±0.36 mm/m 2 /year; p=0.01). Conclusion: Aortic microcalcification activity is increased in aortopathy of patients with bicuspid aortic valve. Loss of aortic microcalcification is associated with more rapid disease progression and represents a promising new approach to the identification of patients at higher risk of aortic complications.

Abstract 3007: The Role Of Myeloperoxidase In The Development Of Abdominal Aortic Aneurysm

Background: Abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disorder characterized by inflammation in the aortic media, extracellular matrix degradation, aortic dilation and rupture. Increasing evidence identifies a role for oxidative stress, although the oxidative reactions involved requires clarification. Myeloperoxidase (MPO) is a pro-inflammatory neutrophil-derived enzyme that promotes cardiovascular disease by catalyzing tissue damaging oxidative reactions. Here we investigated the impact of MPO pharmacological inhibition and gene deletion on AAA. For pharmacological inhibition, the clinically trialed 2-thioxanthine class of irreversible MPO inhibitors was employed. Methods: Apolipoprotein E (ApoE -/- ) or ApoE -/- /MPO -/- gene-knockout mice were infused with angiotensin II (AngII) by osmotic mini-pumps for 28 days and received 2-thioxanthine or vehicle via daily oral gavage. AAA development was monitored by micro-ultrasound measurement of aortic diameter and post-mortem measurement of maximal aortic width at the supra-renal aorta. Atherosclerosis was measured at the aortic sinus by morphometry and aortic arch by en face analysis of oil-red-O-stained lipids. Cardiac fibrosis was measured by picrosirius red staining. Results: AngII infusion afforded an AAA incidence rate of 60% in ApoE -/- mice that was reduced to 25% by 2-thioxanthine treatment. 2-Thioxanthines also inhibited the AngII-mediated increase in aortic diameter and cardiac fibrosis, but not the AngII-induced accelerated development of atherosclerosis at the aortic sinus and arch. Paradoxically, studies in ApoE -/- /MPO -/- mice established that MPO gene-deletion did not affect AngII-induced AAA but significantly attenuated the increase in aortic arch atherosclerosis. Notably, 2-thioxanthines significantly inhibited AAA incidence and severity in AngII-infused ApoE -/- /MPO -/- mice. Conclusion: These studies highlight the complexity surrounding the role of MPO in a murine model of AAA and atherosclerosis. Importantly, this work establishes that 2-thioxanthines can protect against AAA in the absence of MPO, supporting that this clinically trialed MPO inhibitor drug class can target other heme peroxidases in vivo .

Divergent Effects of IL-18- and IL-18R-deficiency on Angiotensin II-induced Abdominal Aortic Aneurysm Formation

Currently, there are no pharmacological treatments for abdominal aortic aneurysms (AAA), and AAA rupture is fatal in ~90% of patients. Aortic inflammation is strongly correlated with the expansion of AAA and recently the NLRP3 inflammasome has been implicated in thedevelopment of AAA. Interleukin (IL)-18, an inflammasome-derived cytokine, exerts pro-inflammatory responses when bound to its cognate IL-18 receptor (IL-18Rα). The current project aimed to determine the effect of IL-18- and IL-18Rα-deficiency on the incidence of angiotensin (Ang) II-induced AAA. Ten-week-old male C57BL/6 (WT), IL-18-deficient ( Il18−/−) and IL-18Rα-deficient ( Il18r1−/−) mice were infused with Ang II (1.44 mg/kg/day, s.c.) for 28 days via osmotic minipump. Ang II-induced AAA incidence differed in all strains. While 52% of WT mice developed AAA (including premature deaths due to rupture), no AAAs were detected in Il18−/− mice (p&lt;0.05, n=20-23). Strikingly, Il18r1−/− mice exhibited a higher incidence of AAA and associated mortality compared to WT mice(88%; p&lt;0.05, n=23-25). Consistent with this finding, in vivo ultrasound imaging confirmed advanced dilation of the abdominal aorta at d7 after Ang II-treatment in Il18r1−/− mice cf. WT mice (1.49 ± 0.13 vs 1.15 ± 0.05 mm; p&lt;0.05; n=23-25). Single cell RNA-sequencing of Ang II-infused mouse aorta revealed Il18r1 gene expression was limited to gamma-delta T cells, suggesting these cells may be driving IL-18 mediated AAA formation. In summary, IL-18-deficiency affords protection from AAA formation, while AAA incidence and severity were augmented in Il18r1−/− mice. Neutralisation of IL-18, but not IL-18Rα inhibition, may represent a novel therapeutic strategy to treat AAA. NHMRC (GNT1143674). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 3014: Bulk And Single-cell Characterization Of The Immune Microenvironment Of Abdominal Aortic Aneurysm

Background: Abdominal aortic aneurysm (AAA), characterized by localized dilation of the abdominal aorta, involves an immune microenvironment that plays a crucial role in disease development. This study aimed to investigate immune cell heterogeneity and functional dynamics in AAA using single-cell RNA sequencing (scRNA-seq) analysis of AAA content and healthy aorta samples. Methods: By analyzing scRNA-seq datasets from AAA content and healthy aorta samples, along with bulk datasets comprising AAA and healthy aortic tissues, we comprehensively profiled the immune microenvironment. Results: The analysis revealed five major cell types in both AAA contents and healthy aortic tissues. Further integrative analysis identified 18 distinct subpopulations, unraveling specific immune cell subtypes within AAA. These subtypes were distinguished based on tissue infiltration, functional variations, immune dynamics, metabolic changes, and communication patterns. Notably, B cells and plasma cells were found to contribute to AAA and thrombus formation. Additionally, cytotoxic CD8+ T cells showed enrichment in cytokine and chemokine receptor interactions, indicating their involvement in AAA development. Two pro-inflammatory macrophage subtypes (LY6E+ and CCL5+) and two pro-inflammatory neutrophil subtypes specific to AAA emerged as significant findings. Particularly, MME+ neutrophils exhibited heightened immune receptor activity and infiltrated AAA tissues, as supported by bulk dataset analysis. Metabolically active, these neutrophils played a vital role in regulating CXCL signaling, enabling effective cell-to-cell communication among immune cells. Conclusions: This study provides a comprehensive understanding of the diverse immune cell populations within AAA and healthy aorta tissues. The findings shed light on their functional characteristics, developmental trajectories, metabolic differences, and intercellular communication patterns, significantly advancing our knowledge of AAA formation and progression.

Predictive Factors for Iliac Limb Occlusions After Endovascular Abdominal Aneurysm Repair: Determined from Aortoiliac Anatomy, Endovascular Procedures, and Aneurysmal Remodeling.

Iliac limb occlusion (ILO) is a serious complication of endovascular abdominal aneurysm repair (EVAR). This study aimed to identify predictive factors for ILO derived from aortoiliac morphology, endovascular procedure-related parameters, and aneurysmal remodeling characteristics. Patient demographics, pre-EVAR anatomical characteristics of the aneurysm, endovascular procedure details, and post-EVAR aneurysmal remodeling outcomes were analyzed and compared using univariate analysis. Statistically significant factors were subsequently subjected to Cox regression and Kaplan-Meier analyses. Between January 2013 and April 2022, 66 patients were included in this study. Fourteen patients presented with ILO and were compared with 52 control patients with patent endograft limb over at least 1-year of follow-up. The tortuosity indices of the common iliac artery (CIA) and endograft iliac limb to vessel oversizing were significantly larger in the ILO group than in the patent endograft limb group. The CIA index of tortuosity ≥1.08, and endograft iliac limb to vessel oversizing ≥18.8% were independent predictors for ILO. During the follow-up of all patients, the proximal aortic neck and CIA diameters increased, aneurysm sac diameter decreased, and aortic neck and aortic length increased. The aortoiliac length increased over time in patients with patent endograft limb but not in patients with ILO. A change in the lowest renal artery-left iliac bifurcation distance ≦0.07 mm increased the risk of ILO. ILO is predisposed to occur when the CIA index of tortuosity ≥1.08 and endograft iliac limb to vessel oversizing ≥18.8% are present. Significant aortoiliac remodeling, including proximal aortic neck dilatation, neck straightening, aneurysmal sac regression, iliac artery enlargement, and aortic lengthening, occurs after EVAR. Aortoiliac elongation was observed in patients with patent endograft limb, but not in patients with ILO. ILO was associated with a change in the lowest renal artery-left iliac bifurcation from the postoperative measurements ≦ 0.07 mm.

FIRST COMPREHENSIVE ECHOCARDIOGRAPHIC ASSESSMENT IN PATIENTS WITH VASCULAR EHLERS-DANLOS SYNDROME WITH OR WITHOUT CELIPROLOL THERAPY AT THE MAXIMUM RECOMMENDED DOSE

Objective: Vascular Ehlers-Danlos syndrome (vEDS) is an inherited connective tissue disorder characterized by arterial fragility. Celiprolol is a beta1-adrenoceptor antagonist with partial beta2 agonist activity that has been shown to reduce rates of vascular events in this setting, though the underlying mechanisms are not yet fully understood. Moreover, few data on echocardiographic assessment are available in patients with vEDS. Design and method: Twenty patients with genetically confirmed diagnosis of vEDS followed at our Institution were divided into two groups (10 patients each) according to whether or not they were on celiprolol therapy at the maximum recommended dose (400 mg daily) for at least 12 months. Both groups were compared to 10 healthy individuals matched for sex, age, body mass index (BMI), and office blood pressure values. Each participant underwent transthoracic echocardiography with tissue Doppler analysis for a comprehensive evaluation of cardiac structure and function. Results: Mean age was 35 years and mean BMI was 21.6 kg/m2. Female sex was prevalent (60%). Left ventricular (LV) internal diameter values tended to be lower in patients with untreated vEDS than in healthy controls, though this difference was not statistically significant (4.33 vs 4.74 cm, respectively; p=0.053). Similar data were observed for LV mass index (56.9 vs 68.6 g/m2; p=0.093), stroke volume (56.6 vs 71.6 mL; p=0.068), and E/A ratio (1.26 vs 1.66; p=0.082), whereas an opposite trend was observed for e’ lateral (13.2 vs 12.2; p=0.096). No statistically significant difference was found between groups in terms of other parameters of LV mass, systolic and diastolic function. A normal LV geometry was found in all the cases. Indices of mechano-energetic efficiency and ventricular-arterial coupling were also similar between groups. No patient presented with aortic root dilation, mitral valve prolapse, valve insufficiency of more than mild degree, or valve stenosis of any degree. Conclusions: Our study suggests that patients with vEDS have normal cardiac mass and geometry, as well as normal systolic and diastolic function. Celiprolol therapy does not seem to significantly influence such aspects. Future studies on larger cohort of patients should confirm these aspects.

Diagnostic Accuracy of Transthoracic Echocardiography for Acute Type A Aortic Syndrome: A Systematic Review and Meta-Analysis

Transthoracic echocardiography (TTE) is currently recognized as the potential first-line imaging test for patients with suspected acute type A aortic syndrome (AAAS). Direct TTE sign for detecting AAAS is positive if there is an intimal flap separating two aortic lumens or aortic wall thickening seen in the ascending aorta. Indirect TTE sign indicates high-risk features of AAAS, such as aortic root dilatation, pericardial effusion, and aortic regurgitation. Our aim is to summarize the existing clinical evidence regarding the diagnostic accuracy of TTE and to evaluate its potential role in the management of patients with suspected AAAS. We included prospective or retrospective diagnostic cohort studies, written in any language, that specifically focused on using TTE to diagnose AAAS from databases such as PubMed, EMBASE, MEDLINE, and the Cochrane Library. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio [1], and hierarchical summary receiver-operating characteristic (HSROC) curve were calculated for TTE in diagnosing AAAS. We applied Quality Assessment of Diagnostic Accuracy (QUADAS-2) tool and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) quality assessment criteria. Ten studies (2886 patients) were included in the meta-analysis. The pooled sensitivity and specificity of direct TTE signs were 58% (95% CI, 38-76%) and 94% (95% CI, 89-97%). For any TTE signs, the pooled sensitivity and specificity were 91% (95% CI, 85-94%) and 74% (95% CI, 61-84%). The diagnostic accuracy of direct TTE signs was significantly higher than that of any TTE signs, as measured by the area under the HSROC curve [0.95 (95% CI, 0.92-0.96) vs. 0.87 (95% CI, 0.84-0.90)] in four studies. Our study suggests that TTE could serve as the initial imaging test for patients with suspected AAAS. Given its high specificity, the presence of direct TTE signs may indicate AAAS, whereas the absence of any TTE signs, combined with low clinical suspicion, could suggest a lower likelihood of AAAS.