Clinical outcome, valve dysfunction, and progressive aortic dilation in a pediatric population with isolated bicuspid aortic valve

Assessment of abnormal transvalvular flow and wall shear stress direction for pediatric/young adults with bicuspid aortic valve: a cross-sectional 4D flow study

BACKGROUND

Aortic dilation is seen in pediatric/young adult patients with bicuspid aortic valve (BAV), and hemodynamic markers to predict aortic dilation are necessary for monitoring. Although promising hemodynamic metrics, such as abnormal wall shear stress (WSS) magnitude, have been proposed for adult BAV patients using 4D flow cardiovascular magnetic resonance, those for pediatric BAV patients have less frequently been reported, partly due to scarcity of data to define normal WSS range. To circumvent this challenge, this study aims to investigate if a recently proposed 4D flow-based hemodynamic measurement, abnormal flow directionality, is associated with aortic dilation in pediatric/young adult BAV patients.

METHODS

4D flow scans for BAV patients (<20 years old) and age-matched controls were retrospectively enrolled. Static segmentation for the aorta and pulmonary arteries was obtained to quantify peak systolic hemodynamics and diameters in the proximal aorta. In addition to peak velocity, wall shear stress (WSS), vorticity, helicity, and viscous energy loss, direction of aortic velocity and WSS in BAV patients was compared with that of control atlas using registration technique; angle differences of >60deg and >120deg were defined as moderately and severely abnormal, respectively. Association between the obtained metrics and normalized diameters (Z-scores) were evaluated at the sinotubular junction, mid ascending aorta, and distal ascending aorta.

RESULTS

Fifty-three BAV patients, including eighteen with history of repaired aortic coarctation, and seventeen controls were enrolled. Correlation between moderately abnormal velocity/WSS direction and aortic Z-scores was moderate to strong at the sinotubular junction and mid ascending aorta (R=0.62-0.81; p<0.001) while conventional measurements exhibited weaker correlation (|R|=0.003-0.47, p=0.009-0.99) in all subdomains. Multivariable regression analysis found moderately abnormal velocity direction and existence of aortic regurgitation (only for isolated BAV group) were independently associated with mid ascending aortic Z-scores.

CONCLUSION

Abnormal velocity and WSS directionality in the proximal aorta was strongly associated with aortic Z-scores in pediatric/young adult BAV patients.

Bicuspid Aortic Valve in Children and Adolescents: A Comprehensive Review

Bicuspid aortic valve (BAV) is the most common congenital heart defect. Prevalence of isolated BAV in the general pediatric population is about 0.8%, but it has been reported to be as high as 85% in patients with aortic coarctation. A genetic basis has been recognized, with great heterogeneity. Standard BAV terminology, recently proposed on the basis of morpho-functional assessment by transthoracic echocardiography, may be applied also to the pediatric population. Apart from neonatal stenotic BAV, progression of valve dysfunction and/or of the associated aortic dilation seems to be slow during pediatric age and complications are reported to be much rarer in comparison with adults. When required, because of severe BAV dysfunction, surgery is most often the therapeutic choice; however, the ideal initial approach to treat severe aortic stenosis in children or adolescents is not completely defined yet, and a percutaneous approach may be considered in selected cases as a palliative option in order to postpone surgery. A comprehensive and tailored evaluation is needed to define the right intervals for cardiologic evaluation, indications for sport activity and the right timing for intervention.

Variation in management of paediatric isolated bicuspid aortic valve: current practice survey

BACKGROUND

Prior to the recent release of appropriate use criteria for imaging valvulopathies in children, follow-up of valvular lesions, including isolated bicuspid aortic valve, was not standardised. We describe current follow up, treatment, and intervention strategies for isolated bicuspid aortic valve with varying degrees of stenosis, regurgitation, and dilation in children up to 18 years old and compare them with newly released appropriate use criteria.

METHODS

Online survey was sent to members of the American Academy of Pediatrics Section on Cardiology and Cardiac Surgery and PediHeartNet.

RESULTS

Totally, 106 responses with interpretable data were received. For asymptomatic patients with isolated BAV without stenosis, regurgitation, or dilation follow-up-intervals increased from 7+/-4 months in the newborn period to 28 +/- 14 months at 18 years of age. Respondents recommended more frequent follow-up for younger patients and those with greater disease severity. More than 80% of respondents treat aortic regurgitation or aortic dilation in the setting of bicuspid aortic valve medically. In general, intervention was recommended once stenosis or regurgitation became severe (stenosis of >4 m/s; regurgitation with LV Z score 4) regardless of age, but was not routinely recommended for younger children (newborn - age 6 years) with severe dilation. Exercise was restricted at 38+/-11 mmHg echocardiographic mean gradient.

CONCLUSIONS

Current follow-up, treatment, and intervention strategies for isolated bicuspid aortic valve deviate from appropriate use criteria. Differences between the two highlight the need to better delineate the disease course, clarify recommendations for care, and encourage wider adoption of guidelines.

The role of machine learning applications in diagnosing and assessing critical and non-critical CHD: a scoping review

Machine learning uses historical data to make predictions about new data. It has been frequently applied in healthcare to optimise diagnostic classification through discovery of hidden patterns in data that may not be obvious to clinicians. Congenital Heart Defect (CHD) machine learning research entails one of the most promising clinical applications, in which timely and accurate diagnosis is essential. The objective of this scoping review is to summarise the application and clinical utility of machine learning techniques used in paediatric cardiology research, specifically focusing on approaches aiming to optimise diagnosis and assessment of underlying CHD. Out of 50 full-text articles identified between 2015 and 2021, 40% focused on optimising the diagnosis and assessment of CHD. Deep learning and support vector machine were the most commonly used algorithms, accounting for an overall diagnostic accuracy > 0.80. Clinical applications primarily focused on the classification of auscultatory heart sounds, transthoracic echocardiograms, and cardiac MRIs. The range of these applications and directions of future research are discussed in this scoping review.

Sports Participation and Exercise Restriction in Children with Isolated Bicuspid Aortic Valve

Our study was to apply the 2015 American Heart Association/American College of Cardiology Athletic Participation Guidelines to a group of otherwise healthy school age children and young adults with bicuspid aortic valve (BAV) and describe the potential competitive sports restriction as they age. We performed a retrospective chart review of children and young adults aged 5 to 22 years with isolated BAV with at least two echocardiograms between 2000 and 2013. Using task force guidelines, exercise restriction was recommended for any of the following: (1) any dilation of the aortic root, (2) any dilation of the ascending aorta, (3) moderate aortic stenosis, (4) severe aortic regurgitation; (5) left ventricular dilation or (6) reduced shortening fraction. Of the 345 patients with isolated BAV, 202 were considered restricted at study entry. The final cohort included 123 children and young adults. Over the course of follow up, 36% (44 of 123) met restriction criteria. The most likely cause for restriction was aortic dilation (34%). Progression of aortic valve disease occurred in a minority of patients (3%). There were no reports of death, dissection or catheter or surgical based intervention. In conclusion, we found that strict adherence to current guidelines would result in restriction of more than 1/3 of school age children and young adults with BAV from some form of competitive athletics during school age years. Strict application of the current guidelines in this age group may lead to over-restriction of youths from competitive sports.

Eccentric Enlargement of the Aortic Sinuses in Pediatric and Adult Patients with Bicuspid Aortic Valves: A Cardiac MRI Study

Aortic root size and cusp fusion pattern have been related to disease outcomes in bicuspid aortic valve (BAV). This study seeks to characterize symmetry of the aortic sinuses in adult and pediatric BAV patients and its relationship to valvulopathy and root aortopathy. Aortic sinus-to-commissure (S-C) lengths were measured on cardiac MRI of adult and pediatric BAV patients with right-and-left coronary (RL) or right-and-non-coronary (RN) leaflet fusion and tricuspid aortic valve (TAV) controls. Coefficient of variance (CoV) of S-C lengths was calculated to quantify sinus asymmetry, or eccentricity. BAV cohort included 149 adults (48 ± 15 years) and 51 children (15 ± 5 years). TAV cohort included 40 adults (60 ± 13 years) and 20 children (15 ± 5 years). In adult and pediatric BAV patients, the non-fused aortic sinus was larger than either fused sinus. In RL fusion, the non-coronary S-C distance was larger than right or left S-C distances in adults (n = 121, p < 0.001) and larger than the right S-C distance in children (n = 41, p = 0.013). Sinus eccentricity (CoV) in BAV patients was higher than in TAV patients (p < 0.001) and did not correlate with age (p = 0.12). CoV trended higher in RL adults with aortic regurgitation (AR) compared to those without AR (p = 0.081), but was lower in RN adults with AR than without AR (p = 0.006). CoV did not correlate to root Z scores (p = 0.06-0.55) or ascending aortic (AAo) Z scores in adults (p = 0.45-0.55) but correlated negatively to AAo Z score in children (p = 0.005-0.03). Most adult and pediatric BAV patients with RL and RN leaflet fusion demonstrate eccentric dominance of the non-fused aortic sinus irrespective of age. The degree of eccentricity varies with valve dysfunction and BAV phenotype but does not relate to the degree of aortic root dilatation, nor does eccentricity correlate with ascending aorta dilatation in adults.

Bicuspid Aortic Valve: An Update in Morphology, Genetics, Biomarker, Complications, Imaging Diagnosis and Treatment

The bicuspid aortic valve, a kind of heart disease that comes from parents, has been paid attention around the world. Although most bicuspid aortic valve (BAV) patients will suffer from some complications including aortic stenosis, aortic regurgitation, endocarditis, and heart dysfunction in the late stage of the disease, there is none symptom in the childhood, which restrains us to diagnose and treatment in the onset phase of BAV. Hemodynamic abnormalities induced by the malformations of the valves in BAV patients for a long time will cause BAV-associated aortopathy: including progress aortic dilation, aneurysm, dissection and rupture, cardiac cyst and even sudden death. At present, preventive surgical intervention is the only effective method used in this situation and the diameter of the aorta is the primary reference criterion for surgery. And the treatment effects are always not satisfactory for patients and clinicians. Therefore, we need more methods to evaluate the progression of BAV and the surgery value and the appropriate intervention time by combining basic research with clinical treatment. In this review, advances in morphology, genetic, biomarkers, diagnosis and treatments are summarized, which expects to provide an update about BAV. It is our supreme expectations to provide some evidences for BAV early screening and diagnosis, and in our opinion, personalized surgical strategy is the trend of future BAV treatment.

4-D flow MRI aortic 3-D hemodynamics and wall shear stress remain stable over short-term follow-up in pediatric and young adult patients with bicuspid aortic valve

BACKGROUND

Children with bicuspid aortic valve (BAV) are at risk for serious complications including aortic valve stenosis and aortic rupture. Most studies investigating biomarkers predictive of BAV complications are focused on adults.

OBJECTIVE

To investigate whether hemodynamic parameters change over time in children and young adults with BAV by comparing baseline and follow-up four-dimensional (4-D) flow MRI examinations.

MATERIALS AND METHODS

We retrospectively included 19 children and young adults with BAV who had serial 4-D flow MRI exams (mean difference in scan dates 1.8±1.0 [range, 0.6-3.4 years]). We compared aortic peak blood flow velocity, three-dimensional (3-D) wall shear stress, aortic root and ascending aortic (AAo) z-scores between baseline and follow-up exams. We generated systolic streamlines for all patients and visually compared their baseline and follow-up exams.

RESULTS

The only significant difference between baseline and follow-up exams occurred in AAo z-scores (3.12±2.62 vs. 3.59±2.76, P<0.05) indicating growth of the AAo out of proportion to somatic growth. There were no significant changes in either peak velocity or 3-D wall shear stress between baseline and follow-up exams. Ascending aortic peak velocity at baseline correlated with annual change in AAo z-score (r=0.58, P=0.009). Visual assessment revealed abnormal blood flow patterns, which were unique to each patient and remained stable between baseline and follow-up exams.

CONCLUSION

In our pediatric and young adult BAV cohort, hemodynamic markers and systolic blood flow patterns remained stable over short-term follow-up despite significant AAo growth, suggesting minimal acute disease progression. Baseline AAo peak velocity was a predictor of AAo dilation and might help in determining pediatric patients with BAV who are at risk of increased AAo growth.

Clinical and pathophysiological aspects of bicuspid aortic valve disease

A bicuspid aortic valve is not only a common congenital heart defect but also an enigmatic condition that can cause a large spectrum of diseases, such as aortic valve stenosis and severe heart failure in newborns whereas aortic dissection in adults. On the contrary, a bicuspid aortic valve can also occur with normal function throughout life and never need treatment. Numerous genetic mechanisms are involved in the abnormal cellular functions that may cause abnormal development of the aortic valve during early foetal life. As several chromosomal disorders are also associated with a bicuspid valve, there does not appear to be an apparent common trigger to the abnormal development of the aortic valve. The clinical care of the bicuspid aortic valve patient has been changed by a significant body of evidence that has improved the understanding of the natural history of the disease, including when to best intervene with valve replacement and when to provide prophylactic aortic root surgery. Moreover, as bicuspid valve disease is also part of various syndromes, we can identify high-risk patients in whom a bicuspid valve is much more unfavourable than in the normal population. This review provides an overview of all aspects of the bicuspid aortic valve condition and gives an updated perspective on issues from pathophysiology to clinical care of bicuspid aortic valve disease and associated aortic disease in asymptomatic, symptomatic, and pregnant patients, as well as our viewpoint on population screening.

Disease progression and variation in clinical practice for isolated bicuspid aortic valve in children

BACKGROUND

Disease progression of an isolated bicuspid aortic valve (BAV) in children is poorly understood and adult management guidelines may not be applicable. Thus, we sought to evaluate disease progression of pediatric isolated BAV and its relationship to current management practices.

METHODS

Children with a BAV and ≤mild aortic stenosis (AS) and/or aortic regurgitation (AR) at the time of initial evaluation were included in this retrospective cohort study (1/2005-12/2014). Outcomes included change in z-scores for aortic root and ascending aorta diameters, cardiac interventions, adverse outcomes, recommended follow-up interval, and frequency of cardiac imaging studies at each follow up evaluation, as well as AS/AR severity at final evaluation. Outcomes were analyzed using generalized mixed-effect models with subject and provider clustering.

RESULTS

BAV disease progression was evaluated in 294 subjects over 4.1 ± 2.4 (range 0.2-9.5) years. Ascending aorta z-scores increased by 0.1/year (P < .001) but aortic root diameter z-scores were unchanged. AS and/or AR progressed to >mild in 9 (3%), 1 subject underwent cardiac intervention, and none had a major complication. Management was evaluated in 454 subjects (1343 encounters) with 27 different cardiologists. The average recommended follow-up interval was 1.5 ± 0.9 years. Younger age at diagnosis, greater aortic root or ascending aorta z-score at diagnosis, ≥mild AS/AR at follow-up, and earlier diagnosis era were associated with shorter recommended follow-up interval (P < .001 for all). Imaging was obtained at 87% of follow-up encounters and was associated with age at encounter with children ≥12 years most frequently imaged (P < .001). Provider accounted for 14% of variability in recommended follow-up interval and 24% of imaging variability (P < .001 for both).

CONCLUSIONS

We found little to no evidence of disease progression in children with an isolated BAV. Given the low risk, close follow-up and frequent cardiac imaging for BAV surveillance may not be warranted for children.

Longitudinal Assessment of the Doppler-Estimated Maximum Gradient in Patients With Congenital Valvar Aortic Stenosis Pre- and Post-Balloon Valvuloplasty

BACKGROUND

Aortic stenosis has been reported to manifest a slow rate of progression in mild disease, with a greater likelihood of progression in patients with moderate-severe disease. The natural history of the Doppler-estimated maximum gradient (DEMG) in patients after balloon aortic valvuloplasty (BAVP) has not previously been studied on a large scale.

METHODS AND RESULTS

A retrospective review was performed of 360 patients from 1984 to 2012 with aortic stenosis, providing a total of 2059 echocardiograms both before and after BAVP. Patients were excluded if they had an intervention within the first 30 days of life. The relationships between the aortic stenosis DEMG and several predictors (age at initial study, body surface area, valve morphology, and initial DEMG) were explored using linear mixed effect models. Patients with a unicommissural aortic valve had a significantly higher rate of progression compared with those with a bicommissural aortic valve (0.81 and 0.45 mm Hg/year; P<0.001). The median rate of progression in the post-BAVP group was significantly lower than the median pre-BAVP rate of progression (n=34; pre-BAVP 3.97 [1.69-8.7] mm Hg/year; post-BAVP 0.40 [-1.80 to 3.88] mm Hg/year; P<0.008). When adjusted for body surface area, there was no significant increase in the DEMG (-0.03 mm Hg/m² per year; P<0.001).

CONCLUSIONS

There is a statistically significant increase in the DEMG over time in patients with aortic stenosis. After balloon dilation, the DEMG rate of change is reduced compared with that pre-dilation. Given the effect of body surface area on DEMG progression, more frequent observation should be made during periods of rapid somatic growth.

Impact of Bicuspid Aortic Valve Morphology on Aortic Valve Disease and Aortic Dilation in Pediatric Patients

Bicuspid aortic valve (BAV) is the most common congenital heart defect. BAV is associated with aortic stenosis and insufficiency, and aortic dilation in adult groups, but data in pediatric groups are limited. We sought to assess the impact of BAV morphology on aortic valve disease and aortic dilation in pediatric patients. We performed a retrospective review of all echocardiograms in patients with isolated BAV who were followed at our institution from July 2002 to July 2012. BAV morphology, aortic valve stenosis and/or insufficiency, and aortic dimensions were measured manually. Comparisons were made between right-left cusp fusion (RL) and right-noncoronary cusp fusion (RN) BAV morphologies. Generalized least square models were fit to analyze the impact of specific variables on aortic dilation. There were 1075 echocardiograms in 366 patients (72% male) with isolated BAV. Aortic valve insufficiency and stenosis were more common in RN (p < 0.001 for both). The median aortic sinus Z score was higher in the RL (0.47; IQR - 0.31 to 1.44) than in the RN group (0.02; - 0.83 to 0.82) (p < 0.001). There was no difference in median ascending aorta Z score between groups. Patients with the highest weights had larger aortas (p < 0.001), but the absolute difference between the highest and lowest weight groups was small (1.5 mm). The impact of BAV morphology on aortic valve disease and aortic dilation in pediatric patients presages that seen in adults. Patient body weight does not make significant clinical impacts on aortic diameters, suggesting that Z scores for aortic diameters should be based on ideal body weights.

Population-based treated prevalence, risk factors, and outcomes of bicuspid aortic valve in a pediatric Medicaid cohort

Background:

We investigated the treated prevalence of bicuspid aortic valve in a pediatric population with congenital heart disease and its incident complications.

Materials and Methods:

A 15-year retrospective data set was analyzed. Selection criteria included age ≤17 years, enrollees in the South Carolina State Medicaid program and diagnosed as having bicuspid aortic valve on one or more service visits.

Results:

The 15-year-treated prevalence of predominantly isolated bicuspid aortic valve was 2% (20/1000) of pediatric congenital heart disease cases, with a non-African American: African-American ratio of 3.5:1, and a male:female ratio of 1.6:1. Aortic stenosis (28.0%), ventricular septal defect (20.6%), and coarctation of the aorta (20.6%) were the most prevalent coexisting congenital heart lesions. Of the 378 bicuspid aortic valve cases examined, 10.3% received aortic valve repair/replacement, which was significantly more likely to be performed in children with diagnosed aortic stenosis (adjusted odds ratio = 12.90; 95% confidence interval = 5.66–29.44). Cohort outcomes over the study period indicated that 9.5% had diagnosed heart failure, but <1% had diagnosed supraventricular tachycardia, infective endocarditis, aneurysm, dissection, or death.

Conclusions:

The majority of isolated bicuspid aortic valve cases without aortic stenosis did not require surgical intervention. Outcomes for cases requiring repair/replacement were relatively benign.

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.

Thoracic aorta 3D hemodynamics in pediatric and young adult patients with bicuspid aortic valve

BACKGROUND

To evaluate the 3D hemodynamics in the thoracic aorta of pediatric and young adult bicuspid aortic valve (BAV) patients.

METHODS

4D flow MRI was performed in 30 pediatric and young adult BAV patients (age: 13.9 ± 4.4 (range: [3.4, 20.7]) years old, M:F = 17:13) as part of this Institutional Review Board-approved study. Nomogram-based aortic root Z-scores were calculated to assess aortic dilatation and degree of aortic stenosis (AS) severity was assessed on MRI. Data analysis included calculation of time-averaged systolic 3D wall shear stress (WSSsys ) along the entire aorta wall, and regional quantification of maximum and mean WSSsys and peak systolic velocity (velsys ) in the ascending aorta (AAo), arch, and descending aorta (DAo). The 4D flow MRI AAo velsys was also compared with echocardiography peak velocity measurements.

RESULTS

There was a positive correlation with both mean and max AAo WSSsys and peak AAo velsys (mean: r = 0.84, P < 0.001, max: r = 0.94, P < 0.001) and AS (mean: rS  = 0.43, P = 0.02, max: rS  = 0.70, P < 0.001). AAo peak velocity was significantly higher when measured with echo compared with 4D flow MRI (2.1 ± 0.98 m/s versus 1.27 ± 0.49 m/s, P < 0.001).

CONCLUSION

In pediatric and young adult patients with BAV, AS and peak ascending aorta velocity are associated with increased AAo WSS, while aortic dilation, age, and body surface area do not significantly impact AAo hemodynamics. Prospective studies are required to establish the role of WSS as a risk-stratification tool in these patients.