Clinical significance of the bicuspid aortic valve

Three-dimensional parametric modeling of bicuspid aortopathy and comparison with computational flow predictions

Bicuspid aortic valve (BAV)-associated ascending aneurysmal aortopathy (namely "bicuspid aortopathy") is a heterogeneous disease making surgeon predictions particularly challenging. Computational flow analysis can be used to evaluate the BAV-related hemodynamic disturbances, which likely lead to aneurysm enlargement and progression. However, the anatomic reconstruction process is time consuming so that predicting hemodynamic and structural evolution by computational modeling is unfeasible in routine clinical practice. The aim of the study was to design and develop a parametric program for three-dimensional (3D) representations of aneurysmal aorta and different BAV phenotypes starting from several measures derived by computed-tomography angiography (CTA). Assuming that wall shear stress (WSS) has an important implication on bicuspid aortopathy, computational flow analyses were then performed to estimate how different would such an important parameter be, if a parametric aortic geometry was used as compared to standard geometric reconstructions obtained by CTA scans. Morphologic parameters here documented can be used to rapidly model the aorta and any phenotypes of BAV. t-test and Bland-Altman plot demonstrated that WSS obtained by flow analysis of parametric aortic geometries was in good agreement with that obtained from the flow analysis of CTA-related geometries. The proposed program offers a rapid and automated tool for 3D anatomic representations of bicuspid aortopathy with promising application in routine clinical practice by reducing the amount of time for anatomic reconstructions.

Morphotype-Dependent Flow Characteristics in Bicuspid Aortic Valve Ascending Aortas: A Benchtop Particle Image Velocimetry Study

The bicuspid aortic valve (BAV) is a major risk factor for secondary aortopathy such as aortic dilation. The heterogeneous BAV morphotypes [left-right-coronary cusp fusion (LR), right-non-coronary cusp fusion (RN), and left-non-coronary cusp fusion (LN)] are associated with different dilation patterns, suggesting a role for hemodynamics in BAV aortopathogenesis. However, assessment of this theory is still hampered by the limited knowledge of the hemodynamic abnormalities generated by the distinct BAV morphotypes. The objective of this study was to compare experimentally the hemodynamics of a normal (i.e., non-dilated) ascending aorta (AA) subjected to tricuspid aortic valve (TAV), LR-BAV, RN-BAV, and NL-BAV flow. Tissue BAVs reconstructed from porcine TAVs were subjected to physiologic pulsatile flow conditions in a left-heart simulator featuring a realistic aortic root and compliant aorta. Phase-locked particle image velocimetry experiments were carried out to characterize the flow in the aortic root and in the tubular AA in terms of jet skewness and displacement, as well as mean velocity, viscous shear stress and Reynolds shear stress fields. While all three BAVs generated skewed and asymmetrical orifice jets (up to 1.7- and 4.0-fold increase in flow angle and displacement, respectively, relative to the TAV at the sinotubular junction), the RN-BAV jet was out of the plane of observation. The LR- and NL-BAV exhibited a 71% increase in peak-systolic orifice jet velocity relative to the TAV, suggesting an inherent degree of stenosis in BAVs. While these two BAV morphotypes subjected the convexity of the aortic wall to viscous shear stress overloads (1.7-fold increase in maximum peak-systolic viscous shear stress relative to the TAV-AA), the affected sites were morphotype-dependent (LR-BAV: proximal AA, NL-BAV: distal AA). Lastly, the LR- and NL-BAV generated high degrees of turbulence in the AA (up to 2.3-fold increase in peak-systolic Reynolds shear stress relative to the TAV) that were sustained from peak systole throughout the deceleration phase. This in vitro study reveals substantial flow abnormalities (increased jet skewness, asymmetry, jet velocity, turbulence, and shear stress overloads) in non-dilated BAV aortas, which differ from those observed in dilated aortas but still coincide with aortic wall regions prone to dilation.

Patient-specific assessment of hemodynamics by computational fluid dynamics in patients with bicuspid aortopathy

OBJECTIVE

Hemodynamics related to eccentric blood flow may factor into the development of bicuspid aortic valve aortopathy. We investigated wall shear stress distribution by means of magnetic resonance imaging-based computational fluid dynamics in patients with a bicuspid aortic valve.

METHODS

Included were 12 patients with a bicuspid aortic valve (aortic stenosis, n = 11; root enlargement, n = 1). Three patients with a normal tricuspid aortic valve (arch aneurysm, n = 1; descending aortic aneurysm, n = 2) were included for comparison. The thoracic aorta geometry was reconstructed by means of 3-dimensional computed tomography angiography, and the bicuspid aortic valve orifice was modeled. Flow rates at the sinotubular junction and 3 aortic branches were measured at various time points by cine phase-contrast magnetic resonance imaging to define boundary conditions for computational fluid dynamics, and the flow was simulated.

RESULTS

Bicuspid aortic valve cusp configurations were type 0 lateral (n = 4), type 0 anterior-posterior (n = 2), type 1 L-R (n = 4), and type 1 R-N (n = 2). Abnormal aortic helical flow was seen in the ascending aorta and transverse arch in all patients with bicuspid aortic valves and was right handed in 11 patients (91%). No such flow was seen in the patients with tricuspid aortic valves. The patients with bicuspid aortic valves were likely to have jet flow/wall impingement against the greater curvature of the proximal ascending aorta, resulting in remarkably increased wall shear stress around the impingement area.

CONCLUSIONS

Computational fluid dynamics simulation is useful for precise evaluation of hemodynamics related to bicuspid aortic valve aortopathy. Such evaluation will advance our understanding of the disease pathophysiology and may facilitate molecular biological investigation.

Functional assessment of thoracic aortic aneurysms - the future of risk prediction?

INTRODUCTION

Treatment guidelines for the thoracic aorta concentrate on size, yet acute aortic dissection or rupture can occur when aortic size is below intervention criteria. Functional imaging and computational techniques are a means of assessing haemodynamic parameters involved in aortic pathology.

SOURCES OF DATA

Original articles, reviews, international guidelines.

AREAS OF AGREEMENT

Computational fluid dynamics and 4D flow MRI allow non-invasive assessment of blood flow parameters and aortic wall biomechanics.

AREAS OF CONTROVERSY

Aortic valve morphology (particularly bicuspid aortic valve) is associated with aneurysm of the ascending aorta, although the exact mechanism of aneurysm formation is not yet established.

GROWING POINTS

Haemodynamic assessment of the thoracic aorta has highlighted parameters which are linked with both clinical outcome and protein changes in the aortic wall. Wall shear stress, flow displacement and helicity are elevated in patients with bicuspid aortic valve, particularly at locations of aneurysm formation.

AREAS TIMELY FOR DEVELOPING RESEARCH

With further validation, functional assessment of the aorta may help identify patients at risk of aortic complications, and introduce new haemodynamic indices into management guidelines.

Bicuspid aortic valve disease: systematic review and meta-analysis of surgical aortic valve repair

Aortic valve repair is still emerging, and its role in the treatment of bicuspid aortic valve disease (BAVD) is not yet fully understood. Our objective is to synthesise available evidence on outcomes after surgical aortic valve repair in patients with BAVD. We conducted a systematic review of clinical studies using prespecified methods for searching, identifying and selecting eligible studies in 4 databases, and synthesising results (PROSPERO 2014:CRD42014014415). 2 researchers independently reviewed full-text articles and extracted data. The results of included studies were quantitatively synthesised in frequentist meta-analyses. We included 11 aortic valve repair studies or study arms with a total of 2010 participants. Pooled estimates for the proportion of patients surviving at 30 days, 1 year, 5 years and 10 years were 0.995 (95% CI 0.991 to 0.995), 0.994 (0.989 to 0.999), 0.945 (0.898 to 0.993) and 0.912 (0.845 to 0.979), respectively. The pooled proportion of late deaths from valve-related causes was 0.008 (0.000 to 0.019) at a mean follow-up of 3.5 years. Proportion of patients with valve-related reinterventions was 0.075 (0.037 to 0.113) at a mean follow-up of 3.9 years, and the linearised reintervention rate was 1.3 (0.7 to 1.9) per 100 patient-years. Outcome reporting was insufficient to pool the results for a number of predefined outcomes. In conclusion, existing evidence on aortic valve repair in BAVD is limited to mostly small case series, case-control and small retrospective cohort studies. Despite the low quality, available evidence suggests favourable survival outcomes after aortic valve repair in selected patients with BAVD. Valve-related reinterventions at follow-up are common in all patients undergoing repair surgery.

Experimental in vivo and ex vivo models for the study of human aortic dissection: promises and challenges

Aortic dissection (AD) is a life-threatening aortopathy with high mortality. To mimic spontaneous AD, investigate the pathogenesis of AD and develop novel therapeutic targets and measures, multiple AD experimental models have been generated, including drugs or chemicals induced experimental models, genetically modified experimental models, surgically or invasively induced experimental models, and ex vivo models. However, the perfect model of AD that replicates every aspect of the natural disease has not be generated yet. This review provides an overview of the experimental models used in AD preclinical research. The value and challenges of each in vivo and ex vivo model are discussed.

Clinical Implication of Aortic Wall Biopsy in Aortic Valve Disease with Bicuspid Valve Pathology

Background

Although unique aortic pathology related to bicuspid aortic valve (BAV) has been previously reported, clinical implications of BAV to aortopathy risk have yet to be investigated. We looked for potential differences in matrix protein expressions in the aortic wall in BAV patients.

Methods

Aorta specimens were obtained from 31 patients: BAV group (n=27), tricuspid aortic valve (TAV) group (n=4). The BAV group was categorized into three subgroups: left coronary sinus-right coronary sinus (R+L group; n=13, 42%), right coronary sinus-non-coronary sinus (R+N group; n=8, 26%), and anteroposterior (AP group; n=6, 19%). We analyzed the expression of endothelial nitric oxide synthase (eNOS), matrix metalloproteinase (MMP)-9, and tissue inhibitor of matrix metalloproteinase (TIMP)-2.

Results

Based on the mean value of the control group, BAV group showed decreased expression of eNOS in 72.7% of patients, increased MMP-9 in 82.3%, and decreased TIMP in 79.2%. There was a higher tendency for aortopathy in the BAV group: eNOS (BAV:TAV)= 53%±7%:57%±11%, MMP-9 (BAV:TAV)=48%±10%:38%±1%. The AP group showed lower expression of eNOS than the fusion (R+L, R+N) group did; 48%±5% vs. 55%±7% (p=0.081).

Conclusion

Not all patients with BAV had expression of aortopathy; however, for patients who had a suspicious form of bicuspid valve, aortic wall biopsy could be valuable to signify the presence of aortopathy.

The genetic component of bicuspid aortic valve and aortic dilation. An exome-wide association study

BACKGROUND

Bicuspid aortic valve is the most common cardiovascular congenital malformation affecting 2% of the general population. The incidence of life-threatening complications, the high heritability, and familial clustering rates support the interest in identifying risk or protective genetic factors. The main objective of the present study was to identify population-based genetic variation associated with bicuspid aortic valve and concomitant ascending aortic dilation.

MATERIALS AND METHODS

A cross-sectional exome-wide association study was conducted in 565 Spanish cases and 484 controls. Single-marker and gene-based association analyses enriched for low frequency and rare genetic variants were performed on this discovery stage cohort and for the subsets of cases with and without ascending aortic dilation. Discovery-stage association signals and additional markers indirectly associated with bicuspid aortic valve, were genotyped in a replication cohort that comprised 895 Caucasian cases and 1483 controls.

RESULTS

Although none of the association signals were consistent across series, the involvement of HMCN2 in calcium metabolism and valve degeneration caused by calcium deposit, and a nominal but not genome-wide significant association, supported it as an interesting gene for follow-up studies on the genetic susceptibility to bicuspid aortic valve.

CONCLUSIONS

The absence of a genome-wide significant association signal shows this valvular malformation may be more genetically complex than previously believed. Exhaustive phenotypic characterization, even larger datasets, and collaborative efforts are needed to detect the combination of rare variants conferring risk which, along with specific environmental factors, could be causing the development of this disease.

Simulations of morphotype-dependent hemodynamics in non-dilated bicuspid aortic valve aortas

Bicuspid aortic valves (BAVs) generate flow abnormalities that may promote aortopathy. While positive helix fraction (PHF) index, flow angle (θ), flow displacement (d) and wall shear stress (WSS) exhibit abnormalities in dilated BAV aortas, it is unclear whether those anomalies stem from the abnormal valve anatomy or the dilated aorta. Therefore, the objective of this study was to quantify the early impact of different BAV morphotypes on aorta hemodynamics prior to dilation. Fluid-structure interaction models were designed to quantify standard peak-systolic flow metrics and temporal WSS characteristics in a realistic non-dilated aorta connected to functional tricuspid aortic valve (TAV) and type-I BAVs. While BAVs generated increased helicity (PHF>0.68) in the middle ascending aorta (AA), larger systolic flow skewness (θ>11.2°) and displacement (d>6.8mm) relative to the TAV (PHF=0.51; θ<5.5°; d<3.3mm), no distinct pattern was observed between morphotypes. In contrast, WSS magnitude and directionality abnormalities were BAV morphotype- and site-dependent. Type-I BAVs subjected the AA convexity to peak-systolic WSS overloads (up to 1014% difference vs. TAV). While all BAVs increased WSS unidirectionality on the proximal AA relative to the TAV, the most significant abnormality was achieved by the BAV with left-right-coronary cusp fusion on the wall convexity (up to 0.26 decrease in oscillatory shear index vs. TAV). The results indicate the existence of strong hemodynamic abnormalities in non-dilated type-I BAV AAs, their colocalization with sites vulnerable to dilation and the superior specificity of WSS metrics over global hemodynamic metrics to the valve anatomy.

Bicuspid Aortic Valve: a Review with Recommendations for Genetic Counseling

Bicuspid aortic valve (BAV) is the most common congenital heart defect and falls in the spectrum of left-sided heart defects, also known as left ventricular outflow tract obstructive (LVOTO) defects. BAV is often identified in otherwise healthy, asymptomatic individuals, but it is associated with serious long term health risks including progressive aortic valve disease (stenosis or regurgitation) and thoracic aortic aneurysm and dissection. BAV and other LVOTO defects have high heritability. Although recommendations for cardiac screening of BAV in at-risk relatives exist, there are no standard guidelines for providing genetic counseling to patients and families with BAV. This review describes current knowledge of BAV and associated aortopathy and provides guidance to genetic counselors involved in the care of patients and families with these malformations. The heritability of BAV and recommendations for screening are highlighted. While this review focuses specifically on BAV, the principles are applicable to counseling needs for other LVOTO defects.

Pathological Investigation of Congenital Bicuspid Aortic Valve Stenosis, Compared with Atherosclerotic Tricuspid Aortic Valve Stenosis and Congenital Bicuspid Aortic Valve Regurgitation

Background

Congenital bicuspid aortic valve (CBAV) is the main cause of aortic stenosis (AS) in young adults. However, the histopathological features of AS in patients with CBAV have not been fully investigated.

Methods and Results

We examined specimens of aortic valve leaflets obtained from patients who had undergone aortic valve re/placement at our institution for severe AS with CBAV (n = 24, CBAV-AS group), severe AS with tricuspid aortic valve (n = 24, TAV-AS group), and severe aortic regurgitation (AR) with CBAV (n = 24, CBAV-AR group). We compared the histopathological features among the three groups. Pathological features were classified using semi-quantitative methods (graded on a scale 0 to 3) by experienced pathologists without knowledge of the patients’ backgrounds. The severity of inflammation, neovascularization, and calcium and cholesterol deposition did not differ between the CBAV-AS and TAV-AS groups, and these four parameters were less marked in the CBAV-AR group than in the CBAV-AS (all p<0.01). Meanwhile, the grade of valvular fibrosis was greater in the CBAV-AS group, compared with the TAV-AS and CBAV-AR groups (both p<0.01). In AS patients, thickness of fibrotic lesions was greater on the aortic side than on the ventricular side (both p<0.01). Meanwhile, thickness of fibrotic lesions was comparable between the aortic and ventricular sides in CBAV-AR patients (p = 0.35).

Conclusions

Valvular fibrosis, especially on the aortic side, was greater in patients with CBAV-AS than in those without, suggesting a difference in the pathogenesis of AS between CBAV and TAV.

Infective endocarditis in patients with bicuspid aortic valve: Clinical characteristics, complications, and prognosis

INTRODUCTION

Bicuspid aortic valve (BAV) is the most frequent congenital cardiac disease. It is associated to a higher risk of cardiovascular complications, including infective endocarditis (IE).

METHODS

Retrospective, observational and single centre study that included all patients with IE diagnosed between 1996 and 2014. An analysis was made of the epidemiological, clinical, microbiological and echocardiographic data, complications during hospital admission, need for surgery, in-hospital mortality, and 1-year follow-up. Cases with endocarditis on prosthetic valves or other locations were excluded, as well as those for which the aortic valve morphology had not been accurately defined. A comparative statistical analysis was performed between BAV and tricuspid (TAV).

RESULTS

Of a total of 328 cases with IE, 118 (35.67%) were on aortic valve, with 18 (16.22%) of them being BAV. The BAV cases were younger than TAV (51±19.06 vs. 60.83±15.73 years, P=.021) and they had less comorbidity (Charlson 0.67±0.77 vs. 1.44±1.64, P=.03).). There was a higher tendency of Staphylococcal origin (38.9 vs. 21.5%, P=.137), and 55.6% showed peri-valvular complications (TAV 16.1%, P=.001), in particular, abscesses (38.9 vs.16.1%, P=.047). BAV was the only predictive factor of peri-valvular complications (OR 7.87, 95% CI; 2.38-26.64, P=.001). Patients with BAV had more surgery during their admission (83.3 vs. 44.1%, P=.004), had less in-hospital mortality, with no statistical significance (5.6 vs. 25.8%, P=.069), and 1-year survival was significantly superior (93.8 vs 69.3%, P=.048).

CONCLUSIONS

Patients with IE on BAV are young, with low comorbidity. They frequently present with peri-valvular complications and they often require early surgery. Compared to TAV cases, in-hospital mortality is lower and 1-year survival is significantly higher.

Altered aortic shape in bicuspid aortic valve relatives influences blood flow patterns

AIMS

Bicuspid aortic valve (BAV) is known to exhibit familial inheritance and is associated with aortopathy and altered aortic haemodynamics. However, it remains unclear whether BAV-related aortopathy can be inherited independently of valve morphology.

METHODS AND RESULTS

Four-dimensional flow magnetic resonance imaging for the in vivo assessment of thoracic aortic 3D blood flow was performed in 24 BAV relatives with trileaflet aortic valves (age = 40 ± 14 years) and 15 healthy controls (age = 37 ± 10 years). Data analysis included aortic dimensions, shape (round/gothic/cubic), and 3D blood flow characteristics (semi-quantitative vortex/helix grading and peak velocities). Cubic and gothic aortic shapes were markedly more prevalent in BAV relatives compared with controls (38 vs. 7%). Ascending aorta (AAo) vortex flow in BAV relatives was significantly increased compared with controls (grading = 1.5 ± 1.0 vs. 0.6 ± 0.9, P = 0.015). Aortic haemodynamics were influenced by aortic shape: peak velocities were reduced for gothic aortas vs. round aortas (P = 0.003); vortex flow was increased for cubic aortas in the AAo (P < 0.001) and aortic arch (P = 0.004); vortex and helix flows were elevated for gothic aortas in the AAo and descending aorta (P = 0.003, P = 0.029). Logistic regression demonstrated significant associations of shape with severity of vortex flow in AAo (P < 0.001) and aortic arch (P = 0.016) in BAV relatives.

CONCLUSION

BAV relatives expressed altered aortic shape and increased vortex flow despite the absence of valvular disease or aortic dilatation. These data suggest a heritable component of BAV-related aortopathy affecting aortic shape and aberrant blood flow, independent of valve morphology.

Hemodynamics through the congenitally bicuspid aortic valve: a computational fluid dynamics comparison of opening orifice area and leaflet orientation

A computational fluid dynamics model of a bicuspid aortic valve has been developed using idealised three-dimensional geometry. The aim was to compare how the orifice area and leaflet orientation affect the hemodynamics of a pure bicuspid valve. By applying physiologic material properties and boundary conditions, blood flow shear stresses were predicted during peak systole. A reduced orifice area altered blood velocity, the pressure drop across the valve and the wall shear stress through the valve. Bicuspid models predicted impaired blood flow similar to a stenotic valve, but the flow patterns were specific to leaflet orientation. Flow patterns developed in bicuspid aortic valves, such as helical flow, were sensitive to cusp orientation. In conclusion, the reduced opening area of a bicuspid aortic valve amplifies any impaired hemodynamics, but cusp orientation determines subsequent flow patterns which may determine the specific regions downstream from the valve most at risk of clinical complications.

Bicuspid and Unicuspid Aortic Valve: Fate of Moderate/Severe Mixed Aortic Valve Disease

OBJECTIVES

There is a paucity of data about mixed aortic valve disease (MAVD) in patients with bicuspid/unicuspid aortic valve (BAV). This study sought to describe the outcomes of patients with moderate/severe MAVD.

METHODS

We queried our database for patients with BAV and moderate/severe MAVD seen between 1994 and 2013. We excluded patients with baseline New York Heart Association (NYHA) III/IV symptoms, left ventricular ejection fraction <50%, aortic dimension >50 mm, and significant disease of other valves. The purpose of the study was to determine the freedom from NYHA III/IV symptoms and aortic valve replacement (AVR).

RESULTS

We identified 138 patients with moderate/severe MAVD; mean age was 51 ± 12 years; 112 (81%) were males; and follow-up was 8.5 ± 4 years. Ninety-two patients (67%) underwent AVR within 3.7 ± 2.5 years. Mechanical prostheses were implanted in 73 patients (79%); 22 patients (26%) and 36 patients (39%) had concomitant coronary artery bypass graft and aorta replacement during AVR respectively. There were no surgical deaths. Freedom from AVR was 84%, 51%, and 20% at 1, 5 and 10 years respectively. Predictors of AVR were age at presentation (hazard ratio [HR] 5.22; confidence interval [CI] 3.10 to 6.64) for every decade increase in age; and having severe stenosis or regurgitation at the time of presentation (HR 1.32; CI 1.05 to 3.16).

CONCLUSIONS

Age and disease severity should be incorporated in the risk assessment of BAV patients with MAVD, and patients with both risk factors should be monitored closely.

Proteomics of Ascending Aortic Aneurysm with Bicuspid or Tricuspid Aortic Valve

Bicuspid aortic valve is often associated with lesions of the ascending aorta, which differ histologically from those in tricuspid valve patients. We undertook proteomic analyses to assess differences at the proteome level. Aortic samples were collected from 20 patients undergoing aortic valve and/or ascending aortic replacement; 9 had a bicuspid valve: 5 with aortic aneurysm (diameter > 50 mm) and 4 without dilation; 11 had a tricuspid valve: 6 with aortic aneurysm and 5 without dilation. Patients with histologically proven connective tissue disorders were excluded. Samples were dissected, solubilized, and subjected to 2-dimensional gel electrophoresis. Gel patterns showed an average of 580 protein spots in samples from bicuspid valve patients, and 564 spots in those with tricuspid valves. Comparative analysis revealed a correlation coefficient of 0.93 for protein expression in the bicuspid valve group compared to the tricuspid group. Three protein spots were significantly over-expressed and 4 were significantly down-regulated in the bicuspid group compared to the tricuspid group. The lowest correlation in protein expression was between non-dilated aortic tissues. These differences between aortic tissues of bicuspid and tricuspid valve patients suggest that mechanisms of aortic dilation might differ, at least in part, between such patients.

Regional Disruptions in Endothelial Nitric Oxide Pathway Associated With Bicuspid Aortic Valve

BACKGROUND

Endothelial nitric oxide (NO) synthase (eNOS) has been implicated in the development of bicuspid aortic valve (BAV) and with differential expression in the ascending aorta of BAV patients. However, little is known about functional disruptions in the eNOS pathway and the effect on BAV-associated aortic dilatation. We tested the hypothesis that eNOS function is regionally diminished in ascending thoracic aortic aneurysms associated with BAV.

METHODS

Thoracic aortic aneurysms specimens were collected from patients with BAV (n = 21) or tricuspid aortic valve (n = 12). Tissue samples were harvested from three circumferential regions corresponding to locations above the right, left, and noncoronary sinuses. Adventitial-stripped specimens containing media and intima only were analyzed for NO synthase 3 gene expression and total eNOS protein. Indicators of eNOS activity (pSer1177-eNOS) and NO bioavailability (phosphorylation of vasodilator-stimulated phosphoprotein at Ser239) were also measured.

RESULTS

NO synthase 3 and eNOS protein were elevated in the right aortic region of BAV specimens compared with tricuspid aortic valve specimens. Activation of eNOS, as indicated by pSer1177-eNOS, was higher in BAV specimens across all regions. Despite increases in eNOS and pSer1177-eNOS, BAV specimens displayed no change in pSer239-vasodilator-stimulated phosphoprotein compared with tricuspid aortic valve specimens.

CONCLUSIONS

BAV is associated with regional disruptions in the eNOS pathway, most markedly in the right aortic region. The discrepancy between increased eNOS activity and the absence of increased NO bioavailability in this region provides insight into physiologic mechanisms potentially underlying the asymmetric dilatation pattern observed in BAV.

Cardiac septic pulmonary embolism: A retrospective analysis of 20 cases in a Chinese population

Based on the source of the embolus, septic pulmonary embolism (SPE) can be classified as cardiac, peripheral endogenous, or exogenous. Cardiac SPEs are the most common.We conducted a retrospective analysis of 20 patients with cardiac SPE hospitalized between 1991 and 2013 at a Chinese tertiary referral hospital.The study included 14 males and 6 females with a median age of 38.1 years. Fever (100%), cough (95%), hemoptysis (80%), pleuritic chest pain (80%), heart murmur (80%), and moist rales (75%) were common clinical manifestations. Most patients had a predisposing condition: congenital heart disease (8 patients) and an immunocompromised state (5 patients) were the most common. Staphylococcal (8 patients) and Streptococcal species (4 patients) were the most common causative pathogens. Parenchymal opacities, nodules, cavitations, and pleural effusions were the most common manifestations observed via computed tomography (CT). All patients exhibited significant abnormalities by echocardiography, including 15 patients with right-sided vegetations and 4 with double-sided vegetations. All patients received parenteral antimicrobial therapy as an initial treatment. Fourteen patients received cardiac surgery, and all survived.Among the 6 patients who did not undergo surgery, only 1 survived. Most patients in our cardiac SPE cohort had predisposing conditions. Although most exhibited typical clinical manifestations and radiography, they were nonspecific. For suspected cases of SPE, blood culture, echocardiography, and CT pulmonary angiography (CTPA) are important measures to confirm an early diagnosis. Vigorous early therapy, including appropriate antibiotic treatment and timely cardiac surgery to eradicate the infective source, is critical.

Systolic flow displacement using 3D magnetic resonance imaging in an experimental model of ascending aorta aneurysm: impact of rheological factors

OBJECTIVES

The impact of systolic flow displacement on the development and progression of ascending aorta dilatation in aortic valve disease is a matter of controversy. Our objective was to study the association between rheological stimuli and development of aortic dilatation in a large animal model of supravalvular aortic stenosis and eccentric flow.

METHODS

Twenty-four pigs weighing 10-14 kg were randomly allocated (ratio 2:1) to either restrictive ascending aortic banding or sham operation. Aortic diameter and systolic flow displacement were assessed by three-dimensional phase-contrast magnetic resonance imaging at 6 and 18 weeks after surgery. Twenty pigs (n = 14, banded vs n = 6, sham) completed full imaging protocol and were included in the analysis. After the last follow-up, a subset of 14 animals was sacrificed for histological analysis.

RESULTS

All banded animals developed significant progressive aortic dilatation both at 6 and 18 weeks, compared with sham-operated pigs: 34.3 ± 4.8 vs 21.4 ± 2.7 mm at 6 weeks (P < 0.001); and 50.0 ± 8.4 vs 38.0 ± 8.3 mm at 18 weeks (P = 0.002). The peak gradient at 6 weeks showed a trend to positively correlate with aortic diameter at 18 weeks (R = 0.50, P = 0.06), whereas the systolic flow displacement at 6 weeks correlated better with aortic diameter at 18 weeks (R = 0.59, P = 0.02). The aortic wall thickness was significantly decreased in the anterior aortic section in banded, compared with sham-operated, pigs (1.5 ± 0.4 vs 2.0 ± 0.1 mm, respectively; P = 0.03). In addition, banded pigs showed a higher degree of cystic medial necrosis and elastin fibre fragmentation, compared with sham-operated animals.

CONCLUSIONS

In this preclinical model of supravalvular aortic stenosis and eccentric flow, we found that systolic flow displacement at earlier stages is positively correlated with the degree of aortic dilatation during follow-up as assessed by three-dimensional phase-contrast magnetic resonance imaging. If our findings are confirmed in further studies, this imaging parameter might be useful to identify those subjects with aortic valve disease who are at risk of developing aortic dilatation at a later stage.

Assessment of aortic valve in regard to its anatomical variants morphology in 2053 patients using 64-slice CT retrospective coronary angiography

BACKGROUND

Bicuspid aortic valve (BAV) is the most common congenital cardiac anomaly. Other aortic valve variants are rare but are associated with an increased incidence of various pathologies of the aortic valve (AV). The aim of this study was to assess the AV function in regard to its anatomical variants morphology in patients who underwent 64-slice coronary computed tomography angiography (CCTA) for suspected or known coronary artery disease.

METHODS

The results of 64-detector retrospective ECG-gated CCTA of 2053 patients (mean age 58 years; 1265 males) were analyzed retrospectively by experienced cardiovascular radiologist. Coronary anatomy (with coronary artery dominance) and the extent of occlusion in the coronary arteries were assessed. Furthermore morphological and functional status of AV variants were analyzed. Among measured parameters were area at the level of AV annulus, orifice and tubular portion of the ascending aorta.

RESULTS

The AV was visualized in all CCTA studies and the analysis of its morphology and function was done in all patients. BAV was found in 19 patients (0.9 %), from which type 0 was diagnosed in five patients (0.2 %) and type 1 in 14 patients (0.7 %) - there was no patient with BAV type 2. Unicuspid (UAV) and quadricuspid (QAV) variant were both observed each in one patient (0.05 %). In rest of the patients from the study group tricuspid AV variant was recognized. Function of AV variants was mostly affected in BAV0 and UAV. Among patients with BAV1 there were patients with normal and abnormal function of AV. QAV variant did not deteriorate AV function. There was no difference in coronary artery disease and dominancy between different anatomical variants of AV.

CONCLUSIONS

During CCTA different valve variants can be detected and detailed analysis of valvular function can be proceeded. Larger values of annulus area, wider diameters of ascending aorta and more stenotic profile were observed in BAV 0, BAV 1 and UAV. Among AV variants morphology and function was mostly affected in patients with BAV 0 and UAV variants, while subjects with BAV1 had normal or abnormal function of the AV. Moreover, we noticed that QAV variant did not deteriorate AV function.

Evaluation of Cardiovascular Changes in Children with BAVs

The objectives of this study were to investigate left ventricular (LV) function, aortic dilation, and atherosclerosis in children with mildly deteriorated isolated bicuspid aortic valve (BAV) function using echocardiographic studies and biochemical markers of atherosclerosis and to correlate results with normal children. Biochemical analyses indicating cardiovascular risk of atherosclerosis and vascular changes in the aorta in relation to BAV were performed in 41 children aged 5-15 years old with isolated BAV and in 25 children with tricuspid aortic valves. Evaluations of aortic valve structures and functions; examinations of the LV M-mode and ascending aorta Doppler; and measurements of the LV Tei index (MPI), propagation velocity, ascending aorta at four levels, and carotid intima-media thickness (CIMT) were performed. There were no statistically significant differences in CIMTs, plasma matrix metalloproteinase-9, tissue metalloproteinase inhibitor-1 levels, or other biochemical parameters indicating cardiovascular risk or atherosclerosis between study and control groups. Deterioration of LV function, which could not be seen with M-mode echocardiography, was evident by MPI. MPI values in the study versus control groups were 0.46 ± 0.080 versus 0.40 ± 0.086 (p < 0.05). Diameters of the aorta in the study and control groups were 19.7 ± 4.7 and 17.2 ± 2.8 mm (p < 0.05) at the sinotubular junction level and 20.6 (14.4-40.5) and 18.3 (12.4-24) mm at the ascending aorta level (p < 0.05). Increased aortic valve insufficiency was related to increased aortic diameter. No sign of atherosclerosis was detected in children with BAV. Deterioration of LV function was seen using MPI, and aortic dilation was related to the severity of aortic valve insufficiency.

Extracellular matrix fiber microarchitecture is region-specific in bicuspid aortic valve-associated ascending aortopathy

OBJECTIVE

Ascending thoracic aortic aneurysm (ATAA) in patients with bicuspid aortic valve (BAV) commonly dilate asymmetrically compared with patients with tricuspid aortic valve (TAV). This discrepancy in aneurysm geometry led us to hypothesize that microarchitectural differences underlie the observed asymmetric dilatation pattern. The purpose of this study was to characterize the microarchitectural distinctions of the extracellular matrix of the 2 phenotypes with a focus on the proportion of radially oriented elastin and collagen fibers in different circumferential aortic regions.

METHODS

Aortic tissue rings were obtained just distal to the sinotubular junction from patients with BAV or TAV undergoing elective aneurysm repair. They were sectioned into three circumferentially based regions according to adjacent aortic sinus segment (left coronary sinus [L], right coronary sinus [R], or noncoronary sinus [N]). Multiphoton microscopy was used to quantify and characterize the number of radially oriented elastin and collagen fibers.

RESULTS

There were fewer radially oriented fibers in medial region N and medial-intimal region R of BAV-ATAAs when compared with TAV-ATAAs (medial region N, amplitude of angular undulation of elastin = 10.67° ± 1.35° vs 15.58° ± 1.91°; P = .041; medial-intimal region R, amplitude of angular undulation of elastin = 9.83° ± 0.83° vs 14.72° ± 1.64°; P = .015). Conversely, fibers became more radially oriented in the medial-intimal region L of BAV-ATAA when compared with TAV-ATAA (amplitude of angular undulation of collagen = 18.67° ± 0.95° vs 14.56° ± 1.37°; P = .041).

CONCLUSIONS

The differential pattern of fiber orientation noted between L and N-R regions help explain the unique pattern of greater curvature dilatation of BAV-ATAA. The distinctions noted in matrix microarchitecture may form the basis of differing aneurysm geometries and aortic wall integrities in ATAAs arising in these different valve morphologies.

Bilateral Macular Roth Spots as a Manifestation of Subacute Endocarditis

A 42-year-old man presented with a 2-day history of impaired vision in the right eye (OD). The best corrected visual acuity (BCVA) (LogMAR) was 1.1 for the right eye and 0.0 for the left eye (OS). Fundus examination revealed white-centered hemorrhages resembling Roth spots in both macular regions. The spectral-domain optical coherence tomography (SD-OCT) showed intraretinal pseudocysts and hyperreflective deposits in the areas corresponding to the Roth spots. Conducted blood tests revealed elevated D-dimer concentration, increased total number of neutrophils, high C-reactive protein concentration, and elevated erythrocyte sedimentation rate. Procalcitonin concentration, platelet count, and body temperature were within normal ranges. A blood culture was ordered and yielded Streptococcus mitis and intravenous antibiotics were started immediately. The patient started complaining of chest and left calf pain. The systemic examination revealed infective endocarditis accompanied by bicuspid aortic valve and paravalvular abscess formation. The patient underwent cardiac surgery with mechanical aortic valve implantation. After recovery, the patient's visual acuities improved fully. Control ophthalmic examination, including SD-OCT, showed no abnormalities.

Bicuspid aortic valve hemodynamics does not promote remodeling in porcine aortic wall concavity

AIM: To investigate the role of type-I left-right bicuspid aortic valve (LR-BAV) hemodynamic stresses in the remodeling of the thoracic ascending aorta (AA) concavity, in the absence of underlying genetic or structural defects.

METHODS: Transient wall shear stress (WSS) profiles in the concavity of tricuspid aortic valve (TAV) and LR-BAV AAs were obtained computationally. Tissue specimens excised from the concavity of normal (non-dilated) porcine AAs were subjected for 48 h to those stress environments using a shear stress bioreactor. Tissue remodeling was characterized in terms of matrix metalloproteinase (MMP) expression and activity via immunostaining and gelatin zymography.

RESULTS: Immunostaining semi-quantification results indicated no significant difference in MMP-2 and MMP-9 expression between the tissue groups exposed to TAV and LR-BAV AA WSS (P = 0.80 and P = 0.19, respectively). Zymography densitometry revealed no difference in MMP-2 activity (total activity, active form and latent form) between the groups subjected to TAV AA and LR-BAV AA WSS (P = 0.08, P = 0.15 and P = 0.59, respectively).

CONCLUSION: The hemodynamic stress environment present in the concavity of type-I LR-BAV AA does not cause any significant change in proteolytic enzyme expression and activity as compared to that present in the TAV AA.

Cardiac axis shift within the cardiac cycle of normal fetuses and fetuses with congenital heart defect

OBJECTIVES

To investigate changes in the cardiac axis (CAx) within the cardiac cycle of normal fetuses and fetuses with congenital heart defects (CHD).

METHODS

This was a retrospective case-control study in which stored videoclips of four-chamber views from 527 prenatal ultrasound examinations performed at 18 + 0 to 36 + 6 weeks of gestation were reviewed. Among the ultrasound scans included, 287 were of normal fetuses (controls) and 240 were of fetuses with CHD. In each case, the CAx was measured at end systole (just before the atrioventricular (AV) valve opened) and at end diastole (just before the AV valve closed). CAx measurements of fetuses with CHD were compared to those of controls.

RESULTS

The mean CAx in the control group was 45.9 ± 8.5° at end systole and 38.3 ± 8.4° at end diastole (P < 0.001), resulting in an average difference of 7.6 ± 3.2°. The mean CAx in fetuses with CHD was 53.4 ± 17.8° at end systole and 47.5 ± 17.3° at end diastole (P < 0.001), resulting in an average difference of 5.9 ± 6.3°. However, in some forms of CHD, such as hypoplastic left heart syndrome and L-transposition of the great arteries, the CAx was greater at end diastole than at end systole, with a difference of more than 5°. In 21.3% of control fetuses, there was a CAx shift within the cardiac cycle of ≥ 10°. Abnormal CAx measured at end systole was strongly associated with CHD.

CONCLUSIONS

Measurement of the CAx at end systole provides values that differ from those when measured at end diastole, in both normal fetuses and those with CHD. We recommend that the CAx be measured at end systole as a greater proportion of fetuses with CHD and fewer normal fetuses have an abnormal CAx at this stage compared to at end diastole. The occurrence of an abnormal CAx and the CAx shift within the fetal cardiac cycle depend on the type of CHD.

General Practitioners' knowledge and use of genetic counselling in managing patients with genetic cardiac disease in non-specialised settings

There have been over 40 cardiac diseases with a genetic cause identified to date. The management of most genetic cardiac diseases (GCDs) now necessitates multidisciplinary care, including the provision of genetic counselling. This study investigated the knowledge and management of GCDs by General Practitioners (GPs). Questionnaires were mailed out to 685 doctors working in general practice in Tasmania, Australia, with 144 responses (21 %) received. Results showed that the majority (77.8 %) of the responding doctors are managing at least one patient with GCD in their practice. However, GPs identified having limited confidence in the appropriate management of these conditions and indicated that they are very dependent on guidance from a cardiologist, including whether to refer a patient to genetic counselling. To our knowledge, this is the first Australian study that looks at the care of patients with GCD in the primary care sector. The knowledge gained will help us provide more appropriate care for patients who do not have immediate access to specialised services, particularly those outside metropolitan areas, and provides evidence for what resources can be offered to doctors working in general practice to help provide quality care for these patients.

Lncing epigenetic control of transcription to cardiovascular development and disease

Transcriptional and epigenetic regulation is critical for proper heart development, cardiac homeostasis, and pathogenesis. Long noncoding RNAs have emerged as key components of the transcriptional regulatory pathways that govern cardiac development as well as stress response, signaling, and remodeling in cardiac pathologies. Within the past few years, studies have identified many long noncoding RNAs in the context of cardiovascular biology and have begun to reveal the key functions of these transcripts. In this review, we discuss the growing roles of long noncoding RNAs in different aspects of cardiovascular development as well as pathological responses during injury or disease. In addition, we discuss diverse mechanisms by which long noncoding RNAs orchestrate cardiac transcriptional programs. Finally, we explore the exciting potential of this novel class of transcripts as biomarkers and novel therapeutic targets for cardiovascular diseases.

The infected heart: ventriculoseptal abscess and intracardiac fistulization

Infective endocarditis is a rare but potentially deadly infection of the endocardial layer, which can involve the valves of the heart among other structures. The extraordinarily rare complication seen in this case involves extensive damage manifesting in an aortic root abscess resulting in an abnormal communication between the aorta and the atrium known as an aortocavitary fistula (Eur Heart J 2005;26:288-297; Pediatr Cardiol 2011;32:1057-1059; J Am Coll Cardiol 1991;18:663-667). As the disease progresses, wading through the complex symptoms, which may seem unrelated, represents a key challenge in diagnosis. This case describes both early and late findings of endocarditis and highlights a rare complication in which rapid diagnosis and early surgical intervention before the development of hemodynamic sequelae are paramount. In this case, infective endocarditis, a great masquerader in this case, provided a challenging diagnostic situation, a very rare complication, and commonalities of disease characteristics that health care provider should appreciate.

A Novel Method for Screening Children with Isolated Bicuspid Aortic Valve

This paper presents a novel processing method for heart sound signal: the statistical time growing neural network (STGNN). The STGNN performs a robust classification by merging supervised and unsupervised statistical methods to overcome non-stationary behavior of the signal. By combining available preprocessing and segmentation techniques and the STGNN classifier, we build an automatic tool for screening children with isolated BAV, the congenital heart malformation which can lead to serious cardiovascular lesions. Children with BAV (22 individuals) and healthy condition (28 individuals) are subjected to the study. The performance of the STGNN is compared to that of a time growing neural network (CTGNN) and a conventional support vector (CSVM) machine, using balanced repeated random sub sampling. The average of the accuracy/sensitivity is estimated to be 87.4/86.5 for the STGNN, 81.8/83.4 for the CTGNN, and 72.9/66.8 for the CSVM. Results show that the STGNN offers better performance and provides more immunity to the background noise as compared to the CTGNN and CSVM. The method is implementable in a computer system to be employed in primary healthcare centers to improve the screening accuracy.

Preliminary Evidence for Aortopathy and an X-Linked Parent-of-Origin Effect on Aortic Valve Malformation in a Mouse Model of Turner Syndrome

Turner syndrome (TS), most frequently caused by X-monosomy (45,X), is characterized in part by cardiovascular abnormalities, including aortopathy and bicuspid aortic valve (BAV). There is a need for animal models that recapitulate the cardiovascular manifestations of TS. Extracellular matrix (ECM) organization and morphometrics of the aortic valve and proximal aorta were examined in adult 39,XO mice (where the parental origin of the single X was paternal (39,X^PO) or maternal (39,X^MO)) and 40,XX controls. Aortic valve morphology was normal (tricuspid) in all of the 39,X^PO and 40,XX mice studied, but abnormal (bicuspid or quadricuspid) in 15% of 39,X^MO mice. Smooth muscle cell orientation in the ascending aorta was abnormal in all 39,X^PO and 39,X^MO mice examined, but smooth muscle actin was decreased in 39,X^MO mice only. Aortic dilation was present with reduced penetrance in 39,XO mice. The 39,XO mouse demonstrates aortopathy and an X-linked parent-of-origin effect on aortic valve malformation, and the candidate gene FAM9B is polymorphically expressed in control and diseased human aortic valves. The 39,XO mouse model may be valuable for examining the mechanisms underlying the cardiovascular findings in TS, and suggest there are important genetic modifiers on the X chromosome that modulate risk for nonsyndromic BAV and aortopathy.

Diseases of the Aorta in Elite Athletes

Sudden cardiovascular deaths in athletes are rare and only a fraction are due to aortic events. There has been concern that the hemodynamic load during exercise may lead to aortic dilation, but aortic dimensions in endurance and strength-trained athletes are only slightly larger than those in sedentary comparison subjects. The presence of a bicuspid aortic valve without significant valvular dysfunction and normal aortic dimensions should not influence eligibility to practice sport. Patients with genetic syndromes associated with aortopathy generally should be restricted from vigorous sports participation. This article reviews the diagnosis and management of diseases of the aorta in athletes.

Current topics on bicuspid aortic valve: clinical aspects and surgical management

Bicuspid aortic valve (BAV) has been identified as the most common heart valve anomaly and is considered to be a heritable disorder that affects various cardiovascular disorders, including aortopathy. Current topics regarding the clinical management of BAV including surgical strategies with or without concomitant aortic repair or replacement are attracting interest, in addition to the pathological and morphological aspects of BAV as well as aortopathy. However, surgical indications are still being debated and are dependent on current clinical guidelines and surgeons' preferences. Although clinical guidelines have already been established for the management of BAV with or without aortopathy, many studies on clinical management and surgical techniques involving various kinds of subjects have previously been published. Although a large number of studies concerning the clinical aspects of BAV have been reviewed in detail, controversy still surrounds the clinical and surgical management of BAV. Therefore, surgeons should carefully consider valve pathology when deciding whether to replace the ascending aorta. In this review, we summarized current topics on BAV and the surgical management of diseased BAV with or without aortopathy based on previous findings, including catheter-based interventional management.

Unicuspid unicommissural aortic valve: an extremely rare congenital anomaly

Unicuspid aortic valve is a rare congenital malformation that usually presents in the 3rd to 5th decade of life-and usually with severe aortic stenosis or regurgitation. It often requires surgical correction. Diagnosis can be made with 2- or 3-dimensional transthoracic or transesophageal echocardiography, cardiac computed tomography, or cardiac magnetic resonance imaging. We report the case of a 31-year-old man who presented with dyspnea on exertion due to severe aortic stenosis secondary to a unicuspid unicommissural aortic valve. After aortic valve replacement, this patient experienced complete heart block that required the placement of a permanent pacemaker.

Bicuspid valve-related aortic disease: flow assessment with conventional phase-contrast MRI

RATIONALE AND OBJECTIVES

Abnormal blood flow with bicuspid aortic valve (BAV) has been characterized with four-dimensional flow magnetic resonance imaging (MRI), but this approach is time consuming and requires technical expertise. We assess the relationship between different leaflets fusion patterns with BAV, eccentric systolic flow, and dilation patterns of the ascending aorta using two-dimensional (2D) phase-contrast (PC) MRI.

MATERIALS AND METHODS

Fifty-nine patients with BAV who underwent cardiac MRI were identified; 47 had right-left (RL) aortic leaflet fusion and 12 had right-noncoronary (RN) fusion. Flow displacement was calculated, and patients with abnormal displacement (>0.1) were classified as either rightward or leftward. Patterns of aortopathy were determined (0-3), and correlation between leaflet fusion, flow direction, aortopathy type, and other clinical parameters was performed with Pearson correlation, the Fisher exact test and chi-square analysis.

RESULTS

Normal systolic flow was seen in 24% of cases and was significantly correlated with normal aortas (P = .011). Abnormal flow displacement with RL fusion was strongly associated with rightward deviation (36 of 37 cases), whereas RN fusion skewed leftward (seven of eight cases; P < .01). In patients with aortopathy, RL fusion was strongly associated with type 2 aortopathy and RN with type 3 aortopathy (P < .01).

CONCLUSIONS

Conventional PC MRI can identify abnormal systolic flow and differences in jet orientation with BAV. RL leaflet fusion is associated with rightward flow deviation and type 2 aortopathy, whereas RN fusion is linked to leftward deviation and type 3 aortopathy. The presence and direction of eccentric flow jets may help risk stratify these patients for valve-related aortic disease.

The quadricuspid aortic valve

The quadricuspid aortic valve is a very rare congenital defect that may be an isolated entity or associated with a multitude of cardiovascular abnormalities. Isolated cases usually manifest late in life with the complication of aortic regurgitation, which can be delayed by early valve replacement. We present a case of quadricuspid aortic valve associated with truncus arteriosus, ventricular septal defect, and interrupted aortic arch.