Bicuspid aortic valve related aortopathy

Mechanisms of aortic dissection: From pathological changes to experimental and in silico models

Aortic dissection continues to be responsible for significant morbidity and mortality, although recent advances in medical data assimilation and in experimental and in silico models have improved our understanding of the initiation and progression of the accumulation of blood within the aortic wall. Hence, there remains a pressing necessity for innovative and enhanced models to more accurately characterize the associated pathological changes. Early on, experimental models were employed to uncover mechanisms in aortic dissection, such as hemodynamic changes and alterations in wall microstructure, and to assess the efficacy of medical implants. While experimental models were once the only option available, more recently they are also being used to validate in silico models. Based on an improved understanding of the deteriorated microstructure of the aortic wall, numerous multiscale material models have been proposed in recent decades to study the state of stress in dissected aortas, including the changes associated with damage and failure. Furthermore, when integrated with accessible patient-derived medical data, in silico models prove to be an invaluable tool for identifying correlations between hemodynamics, wall stresses, or thrombus formation in the deteriorated aortic wall. They are also advantageous for model-guided design of medical implants with the aim of evaluating the deployment and migration of implants in patients. Nonetheless, the utility of in silico models depends largely on patient-derived medical data, such as chosen boundary conditions or tissue properties. In this review article, our objective is to provide a thorough summary of medical data elucidating the pathological alterations associated with this disease. Concurrently, we aim to assess experimental models, as well as multiscale material and patient data-informed in silico models, that investigate various aspects of aortic dissection. In conclusion, we present a discourse on future perspectives, encompassing aspects of disease modeling, numerical challenges, and clinical applications, with a particular focus on aortic dissection. The aspiration is to inspire future studies, deepen our comprehension of the disease, and ultimately shape clinical care and treatment decisions.

Transcatheter Aortic Valve Replacement in Bicuspid Aortic Valve Disease: A Review of the Existing Literature

Transcatheter aortic valve replacement (TAVR) is a minimally invasive procedure used to replace a damaged aortic valve with a prosthetic valve. TAVR has exceeded surgical aortic valve replacement (SAVR) due to shorter procedures and recovery times. Though initially approved for patients with aortic stenosis at a high surgical risk, TAVR's indications have now broadened to include high, intermediate, and low-risk patients. This review focuses on the evolving role of TAVR in patients with bicuspid aortic valves (BAV). We examine the anatomical and hemodynamic differences between tricuspid aortic valve and BAV, highlighting the unique challenges TAVR faces in BAV patients.

Effect of aortic valve phenotype and sex on aorta dilation in patients with aortic stenosis

BACKGROUND

Bicuspid aortic valve (BAV) is often associated with a concomitant aortopathy. However, few studies have evaluated the effect of the aortic valve (AV) phenotype on the rate of dilation of the aorta. This study aimed to compare the progression rate of aorta dimensions according to AV phenotype (BAV vs tricuspid AV (TAV)), fusion type and sex in patients with aortic stenosis (AS).

METHODS

310 patients with AS (224 TAV and 86 BAV) recruited in the Metabolic Determinants of the Progression of Aortic Stenosis study (PROGRESSA, NCT01679431) were included in this analysis. Doppler echocardiography was performed annually to assess AS severity and measure ascending aorta (AA) dimensions. Baseline and last follow-up visit measurements were used to assess the annualised change.

RESULTS

Median AA annualised change was larger in BAV versus TAV (0.33±0.65 mm/year vs 0.21±0.56 mm/year, p=0.04). In the whole cohort, BAV phenotype and higher low-density lipoprotein (LDL) levels were significantly associated with fast progression of AA dilation in univariate analysis (OR 1.80, 95% CI 1.08 to 2.98, p=0.02; 1.37, 95% CI 1.04 to 1.80, p=0.03, respectively). AA dilation rate did not vary according to the BAV subtype (p=0.142). Predictors of AA progression rate were different between valve phenotypes, with higher apolipoprotein B/apolipoprotein A-I ratio, higher baseline peak aortic jet velocity (Vpeak) and smaller baseline AA diameter in the TAV cohort (all p<0.05) versus absence of hypertension, higher LDL levels and smaller baseline AA diameter in the BAV cohort (all p<0.02). In men, higher baseline Vpeak and smaller baseline AA (p<0.001) were independently associated with increased annualised AA dilation, while in women, higher LDL levels (p=0.026) were independently associated with faster AA dilation.

CONCLUSION

This study suggests that BAV is associated with faster dilation of the AA. Predictors of AA dilation are different between valve phenotype and sex, with higher LDL levels being associated with faster AA dilation in BAV.

Effect of Sport Activity on Uncomplicated Bicuspid Aortic Valve: Long-Term Longitudinal Echocardiographic Study

BACKGROUND

The bicuspid aortic valve (BAV) is a congenital heart defect that can lead to certain complications (aortic stenosis, regurgitation, dilatation and endocarditis), the diagnosis and clinical monitoring of which are effectively entrusted to transthoracic echocardiography (TTE). The impact of training on the natural history of the disease remains unclear.

METHODS

A retrospective cohort of athletes with uncomplicated BAV aged 18-50 years, who underwent at least 2 TTEs with a minimum follow-up of 5 years, subdivided according to the level of physical activity during follow-up into ''untrained'' and ''trained'', was collected.

RESULTS

47 athletes (87.3% male, median 21.0, (18.0; 33.0) years) were included. Median follow-up was 11.6 (8.4; 16.3) years. No statistically significant difference in the growing rate of aorta, left ventricle, nor a significant worsening of aortic stenosis and regurgitation was found. Moreover, there was no significant correlation between weekly training minutes during follow-up and the echocardiographic parameters related to heart size and function.

CONCLUSIONS

In BAV without major complications, high training volumes do not correspond to a more rapid and significant deterioration in valve function nor to a more rapid increase in aortic or cardiac chamber size.

Abnormal Cardiac Magnetic Resonance-Derived Ascending Aortic Area Strain Demonstrates Altered Ventriculo-Vascular Function in Marfan Syndrome

PURPOSE

There remains a need for improved imaging markers for risk stratification and treatment guidance in Marfan syndrome (MFS). After aortic root replacement (ARR), vascular remodeling and progressive aneurysm formation can occur due to alterations in up- and downstream wall biomechanics and hemodynamics. We aim to compare the ventriculo-vascular properties of patients with MFS with controls, and investigate the correlation between ascending aortic area strain and descending aortic area strain (DAAS) with other clinical variables.

PATIENTS AND METHODS

Nineteen patients with MFS (47% males), including 6 with ARR were studied. In 26 studies, aortic area strain was measured using cross-sectional cardiac magnetic resonance images at the ascending and proximal descending aortic levels. Left atrial, left ventricular longitudinal, and left ventricle circumferential strain (left atrial longitudinal strain, left ventricular longitudinal strain, and left ventricular circumferential strain, respectively) were measured using cardiac magnetic resonance-feature tracking.

RESULTS

Compared with healthy controls, patients with MFS had significantly impaired left ventricular longitudinal strain and left ventricular circumferential strain (-15.8 ± 4.7 vs -19.7 ± 4.8, P = 0.005, and -17.7 ± 4.0 vs -27.0 ± 4.1, P < 0.001). Left atrial longitudinal strain was comparable between patients with MFS and controls. AAAS was significantly reduced (19.0 [11.9, 23.7] vs 46.1 ± 11.3, P < 0.001), whereas DAAS was not significantly decreased. AAAS and DAAS were negatively correlated with age, whereas no significant associations were identified with left ventricle function indices. No significant differences were observed between the ventriculo-vascular properties of patients with MFS who underwent ARR and those who did not.

CONCLUSION

Patients with MFS demonstrated impaired ventricular and vascular function compared with healthy controls. Further investigations are warranted to determine clinical utility of aortic stiffness indices for predicting primary and repeat aortic events.

Heritable thoracic aortic disease: a literature review on genetic aortopathies and current surgical management

Heritable thoracic aortic disease puts patients at risk for aortic aneurysms, rupture, and dissections. The diagnosis and management of this heterogenous patient population continues to evolve. Last year, the American Heart Association/American College of Cardiology Joint Committee published diagnosis and management guidelines for aortic disease, which included those with genetic aortopathies. Additionally, evolving research studying the implications of underlying genetic aberrations with new genetic testing continues to become available. In this review, we evaluate the current literature surrounding the diagnosis and management of heritable thoracic aortic disease, as well as novel therapeutic approaches and future directions of research.

Changes in aorta hemodynamics in Left-Right Type 1 bicuspid aortic valve patients after replacement with bioprosthetic valves: An in-silico study

Bicuspid aortic valve (BAV) is the most common cardiac congenital abnormality with a high rate of concomitant aortic valve and ascending aorta (AAo) pathologic changes throughout the patient's lifetime. The etiology of BAV-related aortopathy was historically believed to be genetic. However, recent studies theorize that adverse hemodynamics secondary to BAVs also contribute to aortopathy, but their precise role, specifically, that of wall shear stress (WSS) magnitude and directionality remains controversial. Moreover, the primary therapeutic option for BAV patients is aortic valve replacement (AVR), but the role of improved post-AVR hemodynamics on aortopathy progression is also not well-understood. To address these issues, this study employs a computational fluid dynamics model to simulate personalized AAo hemodynamics before and after TAVR for a small cohort of 6 Left-Right fused BAV patients. Regional distributions of five hemodynamic metrics, namely, time-averaged wall shear stress (TAWSS) and oscillating shear index (OSI), divergence of wall shear (DWSS), helicity flux integral & endothelial cell activation potential (ECAP), which are hypothesized to be associated with potential aortic injury are computed in the root, proximal and distal ascending aorta. BAVs are characterized by strong, eccentric jets, with peak velocities exceeding 4 m/s and axially circulating flow away from the jets. Such conditions result in focused WSS loading along jet attachment regions on the lumen boundary and weaker, oscillating WSS on other regions. The jet attachment regions also show alternating streaks of positive and negative DWSS, which may increase risk for local tissue stretching. Large WSS magnitudes, strong helical flows and circumferential WSS have been previously implicated in the progression of BAV aortopathy. Post-intervention hemodynamics exhibit weaker, less eccentric jets. Significant reductions are observed in flow helicity, TAWSS and DWSS in localized regions of the proximal AAo. On the other hand, OSI increases post-intervention and ECAP is observed to be low in both pre- and post-intervention scenarios, although significant increases are also observed in this ECAP. These results indicate a significant alleviation of pathological hemodynamics post AVR.

Effect of ascending aorta replacement on the long-term outcomes of bicuspid aortic valve repair

OBJECTIVE

The study objective was to determine the effect of sinutubular junction stabilization on long-term outcomes of bicuspid aortic valve repair.

METHODS

From January 1998 to January 2020, 419 patients underwent bicuspid aortic valve repair with ascending aorta replacement and 421 without (bicuspid aortic valve repair alone). Propensity score matching (97 pairs) was used to compare outcomes.

RESULTS

Before matching, prevalence of severe aortic regurgitation at 10 years was 5.4% after bicuspid aortic valve repair + ascending aorta replacement and 10% after bicuspid aortic valve repair alone; aortic valve gradient was 20 mm Hg after bicuspid aortic valve repair + ascending aorta replacement and 19 mm Hg after bicuspid aortic valve repair alone. Ten-year freedom from reoperation overall was 79% after bicuspid aortic valve repair + ascending aorta replacement and 75% after bicuspid aortic valve repair alone; freedom from late aortic regurgitation was 93% after bicuspid aortic valve repair + ascending aorta replacement and 92% after bicuspid aortic valve repair alone; and freedom from aortic stenosis was 87% after bicuspid aortic valve repair + ascending aorta replacement and 93% after bicuspid aortic valve repair alone. Ten-year survival was 95% after bicuspid aortic valve repair + ascending aorta replacement and 96% after bicuspid aortic valve repair alone. After matching, prevalence of severe aortic regurgitation at 10 years was 11% after bicuspid aortic valve repair + ascending aorta replacement and 9.1% after bicuspid aortic valve repair alone (P = .33); aortic valve gradient was 16 mm Hg after bicuspid aortic valve repair + ascending aorta replacement and 25 mm Hg after bicuspid aortic valve repair alone (P < .0001). Ten-year freedom from reoperation was 85% after bicuspid aortic valve repair + ascending aorta replacement and 72% after bicuspid aortic valve repair alone (P = .08) overall. Ten-year freedom from reoperation for late aortic regurgitation was 88% after bicuspid aortic valve repair + ascending aorta replacement and 86% after bicuspid aortic valve repair alone (P = .65). Freedom from aortic stenosis was 97% after bicuspid aortic valve repair + ascending aorta replacement and 91% after bicuspid aortic valve repair alone (P = .03). Ten-year survival was 96% after bicuspid aortic valve repair + ascending aorta replacement and 96% after bicuspid aortic valve repair alone (P = .16).

CONCLUSIONS

Bicuspid aortic valve repair with or without ascending aorta replacement is associated with good short- and long-term outcomes. Bicuspid aortic valve repair + ascending aorta replacement has a minimal effect on long-term repair durability. Sinutubular junction stabilization should not be performed for the sole purpose of long-term repair durability.

Realignment of the ventricular septum in tetralogy of Fallot using (partial) direct closure of the ventricular septal defect: Long-term follow-up and comparison to conventional patch repair

Objectives

Aortic dilatation and regurgitation after surgical repair of tetralogy of Fallot (TOF) is known, and beside other factors, mainly addressed to an intrinsic aortopathy. In 2011, we reported the influence of realingement of the left ventricular outflow tract (LVOT) by (partial) direct closure of the ventricular septal defect (VSD) in TOF on aortic structures and function. We now evaluated the further follow-up of this cohort and compared the results to a matched group of TOF patients with classical VSD patch closure.

Patients and Methods

Forty patients with TOF treated between 2003 and 2008 are included in the study, with 20 patients each in the VSD (a) (partial) direct closure and (b) patch closure group. Follow-up time after surgery was 12.3 years (11.3-13.0).

Results

Patient characteristics, echocardiographic measurements, and surgical and intensive care unit parameters were not significantly different between both groups. After surgery and during long-term follow-up, realignement of the LVOT, shown by the angle between the interventricular septum and the anterior aortic annulus in long axis view in echocardiography, was lower in Group A (34 vs. 45°, P < 0.0001). No differences in LVOT or aortic annulus size, aortic regurgitation, or dilation of the ascending aorta and right ventricular outflow tract gradients were found. Transient rhythm disturbances were found in 3 patients in each group, with only one persistent complete atrioventricular block in Group B.

Conclusion

(Partial) direct closure of the VSD in TOF leads to a better realignement of the LVOT and showed comparable short- and long-term results without higher risk for rhythm disturbances during follow-up.

Isometric Exercise Increases the Diameter of the Ascending Aorta in Youth with Bicuspid Aortic Valves

Central arterial pressure rises to much higher levels during heavy isometric exercise compared to other forms of exercise. For this reason, patients with bicuspid aortic valves (BAV) are often restricted from heavy isometric exercise. Although this approach may be theoretically appealing, no data exist regarding the efficacy of this activity restriction.Patients between 12 and 21 years old with isolated BAV were enrolled if they had a previous echocardiogram at least 2 years prior to the current clinic visit. Patients were excluded if they had additional congenital heart disease, a diagnosed syndrome, or had undergone a procedure involving the aortic valve or ascending aorta. Patients completed a questionnaire regarding frequency and intensity of isometric exercise during the 3-month period prior to the visit. We compared aortic dimensions (Z-score), aortic stenosis, and aortic insufficiency between an echocardiogram performed as part of the current visit and one obtained 2-5 years previously using paired t tests and multivariable regression controlling for age, gender, degree of aortic stenosis, and the presence of isometric exercise. In this sample of 50 adolescents with isolated bicuspid aortic valve, 30 (60%) subjects did not participate in any isometric exercise. Over an average of 2.9 years (SD 0.9 years), we did not find a significant difference between changes in the Z-score diameters of the aortic root (0.9 vs 0.9, p = 0.913) and ascending aorta Z-score (2.9 vs 2.9, p = 0.757), between subjects engaging and not engaging in isometric exercise. Further, we did not find that changes in valve function (i.e., aortic stenosis and aortic insufficiency) differed between the two groups.In this sample of adolescents with isolated bicuspid aortic valve, there was no medium-term increase in aortic dilation or worsening valve function in those who engaged in isometric exercise versus those who refrained from isometric exercise.

Prognostic Implications of Bicuspid and Tricuspid Aortic Valve Phenotype on Progression of Moderate Aortic Stenosis and Ascending Aorta Dilatation

Studies on the impact of aortic valve anatomy (bicuspid aortic valve [BAV] or tricuspid aortic valve [TAV]) on the progression of moderate aortic stenosis (AS) and ascending aorta (AA) dilatation and its prognostic implications are limited. From 1991 to 2016, 288 asymptomatic patients with moderate AS detected during index echocardiography with at least 1 year of echocardiographic follow-up were retrospectively studied. Baseline clinical and echocardiographic characteristics were compared between patients with BAV (n = 80) and patients with TAV (n = 208). Co-primary outcomes were 1-year hemodynamic and anatomic progression of AS and AA dilatation. Secondary end points were the incidence of AA rapid progressors, all-cause mortality, aortic valve replacement, and congestive heart failure. Determinants of AS progression, AA diameters, AA dilatation, and prognostic outcomes were evaluated. Similar 1-year progression of the aortic valve peak velocity, V_max (9 ± 18 vs 9 ± 23 cm/s), mean gradient (1.5 ± 2.3 vs 1.3 ± 3.2 mm Hg), and aortic valve area (AVA) (-0.04 ± 0.09 vs -0.05 ± 0.10 cm²) were noted for BAV and TAV groups, respectively. One-year progressions of AA were similar at Valsalva (0.11 ± 0.88 vs 0.14 ± 1.10 mm) and tubular levels (0.12 ± 0.68 vs 0.30 ± 1.51 mm) in BAV and TAV groups, respectively. A trend toward increased rapid AA progression in patients with BAV (31.3%) was observed compared with patients with TAV (14.8%, p = 0.099). BAV was associated with progression of V_max (β = 0.17, p = 0.036), the dimensionless index (β = -0.17, p = 0.008), and AVA (β = -0.14, p = 0.048), but not mean gradient after adjusting for age, baseline severity indexes, gender, hypertension, diabetes, and body surface area. Although BAV was a determinant of larger baseline AA diameter, there was no significant association between BAV and AA rapid progressors. Adjusted Kaplan-Meier curves demonstrated no differences in congestive heart failure, aortic valve replacement, or mortality between valve morphology. In conclusion, there was a similar 1-year disease progression in terms of AVA, V_max, mean gradient, and AA diameters between patients with BAV and patients with TAV. BAV was associated with a significant increase in V_max, dimensionless index, and AVA after adjusting for important confounders. Close and prolonged follow-up is warranted in both groups of patients.

Mid-term follow-up of aortic valve replacement for bicuspid aortic valve

OBJECTIVE

The purpose of this study was to evaluate the mid-term outcome of aortic valve replacement for bicuspid aortic valve and tricuspid aortic valve and the related risk factors.

METHODS

From January 2014 to June 2019, 177 tricuspid aortic valve patients and 101 bicuspid aortic valve patients who underwent aortic valve replacement in our hospital were collected. 1:1 propensity score matching analysis was used to control the bias in patient selection. The perioperative and follow-up data between the two groups were compared. Independent risk factors which were associated with the continued dilatation of the ascending aorta were identified by univariate or multivariate logistic regression analysis.

RESULTS

After the matching procedure, 160 patients were included in the analysis (80 in each group). Baseline characteristics, intraoperative, and perioperative outcomes were similar between the two groups (all p > 0.05). Moreover, 67 patients in the tricuspid aortic valve group and 70 in the bicuspid aortic valve group completed the follow-up. The ascending aorta change, annual change rate, and the proportion of continuous dilation of ascending aorta in bicuspid aortic valve group were significantly higher than those in the tricuspid aortic valve group (p < 0.05). Multivariate logistic regression analysis showed that type 1 in bicuspid aortic valve (OR 5.173; 95% CI 1.772, 15.101; p = 0.003), aortic regurgitation (OR 3.673; 95% CI 1.133, 11.908; p = 0.030), and aortic valve stenosis with regurgitation (OR 6.489; 95% CI 1.726, 24.404; p = 0.006) were independent risk factors for the continued dilatation of the ascending aorta in all AV patients. Furthermore, the multivariate logistic regression analysis showed that type 1 in bicuspid aortic valve (OR 5.157; 95% CI 1.053, 25.272; p = 0.043), age ≥ 40 years (OR 6.956; 95% CI 1.228, 39.410; p = 0.028), and aortic regurgitation (OR 4.322; 95% CI 1.174, 15.911; p = 0.028) were independent risk factors for the continued dilatation of the ascending aorta in bicuspid aortic valve patients.

CONCLUSION

Compared with tricuspid aortic valve patients, the ascending aorta of bicuspid aortic valve patients is more likely to continue to enlarge after aortic valve replacement. Type 1 in bicuspid aortic valve, age ≥ 40 years, and aortic regurgitation were the independent risk factors.

Therapeutic approach comparison in bicuspid aortic valve aortopathy and clinical practice implications

Bicuspid aortic valve (BAV) is the most common heart valve malformation, and it may be associated with the development of long-term complications, such as aortic stenosis (AS) secondary to valvular calcification and aortic insufficiency (AI), with or without ascending aortic aneurysm (AAA). This study was performed at the Institute of Cardiovascular Diseases, Timişoara, Romania, from 2015 through 2018 and included a total of 105 patients with BAV. Out of the 105 BAV patients, 14 displayed AAA, alongside either AS or AI, and were selected undergo aortic valve replacement (AVR) alongside surgical replacement or aortoplasty of the ascending aorta, and the elastic fiber loss in the ascending aortic wall was evaluated for each patient. Two surgical interventions used alongside AVR in BAV patients with AAA and AS or AI were compared in this study: reduction ascending aortoplasty (RAA) and ascending aorta replacement (AAR). Postoperative follow-ups have shown RAA is useful short-term but that, in contrast to AAR, it leads to aortic redilatation over time. These results can contribute to a major future meta-analysis with the goal of improving the current clinical practice guidelines for BAV aortopathy.

Fate of mild-to-moderate bicuspid aortic valve disease untreated during ascending aorta replacement

BACKGROUND

Bicuspid aortic valve (BAV) is the most common congenital heart defect and it is responsible for an increased risk of developing aortic valve and ascending aorta complications. In case of mild to moderate BAV disease in patients undergoing supracoronary ascending aorta replacement, it is unclear whether a concomitant aortic valve replacement should be performed.

METHODS

From June 2002 to January 2020, 75 patients with mild-to-moderate BAV regurgitation (±mild-to-moderate stenosis) who underwent isolated supracoronary ascending aorta replacement were retrospectively analyzed. Clinical and echocardiographic follow-up was 100% complete (mean: 7.4 ± 3.9 years, max: 16.4). Kaplan-Meier estimates were employed to analyze long-term survival. Cumulative incidence function (CIF) for time to reoperation, recurrence of aortic regurgitation (AR) ≥3+ and aortic stenosis (AS) greater than moderate, with death as competing risk, were computed.

RESULTS

There was no hospital mortality and no cardiac death occurred. Overall survival at 12 years was 97.4 ± 2.5%, 95% confidence interval (CI: 83.16-99.63). At follow-up there were no cases of aortic root surgery whereas three patients underwent AV replacement. At 12 years the CIF of reoperation was 2.6 ± 2.5%, 95% CI [0.20-11.53]. At follow-up, AR 3+/4+ was present in 1 pt and AS greater than moderate in 3. At 12 years the CIF of AR more than 2+/4+ was 5.1 ± 4.98% and of AS more than moderate 6.9 ± 3.8%.

CONCLUSIONS

In our study mild to moderate regurgitation of a BAV did not do significantly worse at least up to 10 years after isolated supracoronary ascending aorta replacement.

Is there a role for autophagy in ascending aortopathy associated with tricuspid or bicuspid aortic valve?

Autophagy is a conserved process by which cytoplasmatic elements are sequestered in vesicles and degraded after their fusion with lysosomes, thus recycling the precursor molecules. The autophagy-mediated removal of redundant/harmful/damaged organelles and biomolecules plays not only a replenishing function, but protects against stressful conditions through an adaptive mechanism. Autophagy, known to play a role in several pathological conditions, is now gaining increasing attention also in the perspective of the identification of the pathogenetic mechanisms at the basis of ascending thoracic aortic aneurysm (TAA), a localized or diffused dilatation of the aorta with an abnormal widening greater than 50 percent of the vessel's normal diameter. TAA is less frequent than abdominal aortic aneurysm (AAA), but is encountered with a higher percentage in patients with congenital heart disease or known genetic syndromes. Several biological aspects of TAA pathophysiology remain to be elucitated and therapeutic needs are still widely unmet. One of the most controversial and epidemiologically important forms of TAA is that associated with the congenital bicuspid malformation of the aortic valve (BAV). Dysregulated autophagy in response, for example, to wall shear stress alterations, has been demonstrated to affect the phenotype of vascular cells relevant to aortopathy, with potential consequences on signaling, remodeling, and angiogenesis. The most recent findings and hypotheses concerning the multiple aspects of autophagy and of its dysregulation are summarized, both in general and in the context of the different vascular cell types and of TAA progression, with particular reference to BAV-related aortopathy.

Polyamines and microbiota in bicuspid and tricuspid aortic valve aortopathy

Polyamines are small aliphatic cationic molecules synthesized via a highly regulated pathway and involved in general molecular and cellular phenomena. Both mammalian cells and microorganisms synthesize polyamines, and both sources may contribute to the presence of polyamines in the circulation. The dominant location for microorganisms within the body is the gut. Accordingly, the gut microbiota probably synthesizes most of the polyamines in the circulation in addition to those produced by the mammalian host cells. Polyamines are mandatory for cellular growth and proliferation. Established evidence suggests that the polyamine spermidine prolongs lifespan and improves cardiovascular health in animal models and humans through both local mechanisms, involving improved cardiomyocyte function, and systemic mechanisms, including increased NO bioavailability and reduced systemic inflammation. Higher levels of polyamines have been detected in non-dilated aorta of patients affected by bicuspid aortic valve congenital malformation, an aortopathy associated with an increased risk for thoracic ascending aorta aneurysm. In this review, we discuss metabolism of polyamines and their potential effects on vascular smooth muscle and endothelial cell function in vascular pathology of the thoracic ascending aorta associated with bicuspid or tricuspid aortic valve.