Valve Disease In Children Research Articles

Long-term outcomes of mitral valve repair in children.

Mitral Valve Disease in children presents unique challenges due to the wide range of associated pathologies and the complexities of pediatric cardiac anatomy. Mitral valve repair in this demographic is preferred over replacement due to the drawbacks associated with prosthetic valves in young patients, such as the need for long-term anticoagulation and issues with prosthetic size and growth. This retrospective study reviewed pediatric patients under 18 years who underwent mitral valve repair between January 2002 and December 2023. Exclusion criteria included patients with atrioventricular septal defects or single-ventricle physiology. Surgical outcomes were assessed using preoperative and postoperative transthoracic echocardiography, with follow-up data analyzed via Kaplan-Meier survival estimates. The study included 47 patients with a median age of 4 years. Surgical techniques varied based on the specific mitral valve pathology. The overall early mortality was 6.3%, and the one and ten-year survival rates were 93.6 ± 3.6% and 91.4 ± 4.1%, respectively. Most patients showed improved or stable postoperative cardiac function during a median follow-up of 105 months. Notably, the rate of freedom from re-operation at ten years was 85.1 ± 6.9%, highlighting the durability of the surgical interventions. Mitral valve repair in children demonstrates favorable long-term outcomes with low mortality and reoperation rates, particularly when performed at an older age to accommodate growth and avoid the complexities of smaller, more delicate cardiac structures. These findings suggest that mitral valve repair should be considered a viable and effective option for managing pediatric MVD, with a personalized approach essential for optimizing outcomes.

Rheumatic valve disease in children still a burden in sub-Saharan Africa: Diagnostic, therapeutic and prognostic aspects in two hospitals in Central Africa subregion

Rheumatic valve disease in children still a burden in sub-Saharan Africa: Diagnostic, therapeutic and prognostic aspects in two hospitals in Central Africa subregion

Ozaki technique versus ross operation for complex aortic valve diseases in children: A retrospective cohort study.

The Ozaki technique demonstrated promising results in adults, but few studies reported on pediatric patients with limited follow-up time. This study aimed to evaluate the mid-term results of Ozaki technique compared with Ross operation for complex aortic valve (AV) diseases in children. One hundred and seventeen children underwent either Ozaki (n = 64) or Ross (n = 53) operation from January 2017 to December 2023. The primary endpoint was incidence of moderate or severe regurgitation/stenosis (AR/AS) post procedure. No significant difference was observed in age (6.5±3.4 vs. 7.9±4.3 years) and weight (25.9±15.5 vs. 31.0±25.9kgs) at surgery. The Ozaki group had significantly more patients in heart failure (20.3% vs. 1.9%, P = 0.003) before surgery and more patients needed ECMO installation (6.3% vs. 0, P = 0.125) after surgery. The Ozaki group were in worse status with more patients occurred heart failure (20.3% vs. 1.9%, P = 0.003) before surgery and needed ECMO installation (6.3% vs. 0, P = 0.125) after surgery. During follow up (20.4±17.3 vs. 22.7±22.8 months, P = 0.526), five patients (7.8%) in Ozaki group but no patients in Ross group required reoperations. The incidence of moderate or severe AR (28.1% vs. 3.1%) and AS (31.3% vs. 5.7%) were significantly higher than Ross group. Multivariate analysis identified lower age [HR:1.282 (95%CI:1.075-1.529), P = 0.006] and ECMO installation [HR:0.126 (0.018-0.887), P = 0.037] to be risk factors for moderate or severe AR, and higher aortic transvalvular gradient before discharge was confirmed as the only risk factor for moderate or severe AS (≥36mmHg) at follow up in Ozaki group. Ozaki technique may be used as a palliative procedure for complex AV diseases in children, but its' mid-term results were not durable as Ross surgery, especially younger patients.

A midterm follow-up study of the application of a confluent aortic valve neocuspidization technique with pericardium in children.

The treatment of aortic valve diseases in children remains a great challenge. We aim to report outcomes and midterm follow-up data of our confluent neocuspidization technique with pericardium for aortic valve replacement (AVR) in children. A retrospective analysis was performed on all 20 children who underwent the confluent neocuspidization technique with pericardium at Children's Hospital of Fudan University from March 2017 to May 2022. Outcome measures included echocardiographic measurements, surgical intervention, and mortality. A total of 20 patients (17 males vs. 3 females), with a median age of 7.5 years [min-max, 0.3-12 years; interquartile range (IQR), 4.4-9.7 years], a median body weight of 24.0 kg (min-max, 6.0-52.3 kg; IQR, 15.6-31.0 kg), and median aortic valve annulus size before surgery of 19.0 mm (min-max, 11.0-25.0 mm; IQR, 17.1-21.5 mm), underwent the neocuspidization technique with pericardium (17 autologous pericardia and 3 bovine patch). With 50% of bicuspid aortic valve and 50% of tricuspid, they were respectively diagnosed as aortic stenosis (AS) (7/20, 35%), aortic regurgitation (AR) (8/20, 40%) and mixed AS and AR (AS & AR) (5/20, 25%). The median postoperative follow-up time was 19 months (min-max, 5-61 months; IQR, 16.3-35 months). The peak pressure gradient across the aortic valve decreased from 81.0±37.0 mmHg in AS group and AS & AR group before surgery to 25.9±15.8 mmHg within 24 hours after surgery (P<0.001) and was mostly around 25 mmHg during follow-up. All patients presented mild or less than mild regurgitation within 24 hours after surgery. There were no hospital mortalities. Three patients needed reintervention during follow-up. There was one late death related to mitral valve stenosis. Though the confluent neocuspidization technique with pericardium provided immediate relief of significant AS or regurgitation, the midterm outcome was suboptimal. More research is needed to find the optimal material for AVR.

Risk factors for mitral valve dysfunction, reoperation and death following repair of the primary mitral valve disease in children.

After primary mitral valve (MV) repair, residual mitral valve regurgitation (MR) and recurred mitral valve stenosis (MS) are the principal occurrences. This study's purpose is to identify the risk factors of MV dysfunction, reoperation and death following repair of primary MV diseases. We retrospectively reviewed 98 patients (47 males and 51 females) with primary MV diseases between January 2013 and December 2021. The median age was 34 months [interquartile range (IQR), 11.4-59] for male and 24 months (IQR, 7.35-72) for female. The left ventricular ejection fraction (LVEF), the left ventricular end-diastolic volume index (LVEDVI) and left ventricular end-systolic volume index (LVESVI) were assessed to evaluate patient's left ventricular function. Risk factors that increased the likelihood of MV dysfunction, reoperation and death after surgery were investigated. During the 23.5 months (IQR, 9-44.5) of follow-up, 5 (5.1%) patients died, including one early death and two late deaths (n=3; 3.9%) in the MR group and one early death and one late death (n=2; 9.1%) in the MS group. Seven (9.2%) patients in the primary MR disease group and 2 (9.1%) patients in the primary MS disease group required a second MV operation for a total reoperation rate of 9.2% (9/98). As of the most recent follow-up, 34 patients experienced MV dysfunction. No significant difference was recorded between primary MR and MS disease groups in Kaplan-Meier freedom from MV dysfunction and reoperation. Mixed MV pathology (P=0.014) acted as an independent risk factor for MV dysfunction, and ≥ moderate MR at 24 h after first surgery (P=0.014) an independent risk factor for MV reoperation. Double-orifice MV technique (P=0.002), MV reoperation (P=0.023) and severe MR at 24 h after first surgery (P=0.028) were independent risk factors for death. The Kaplan-Meier freedom from MV dysfunction and reoperation were comparable between primary MR and MS disease groups. A high probability of MV dysfunction was predicted due to the mixed MV pathology. Patients with ≥ moderate MR at 24 h after first surgery had a higher risk of MV reoperation. Double-orifice MV technique, MV reoperation and severe MR at 24 h after first surgery had a higher risk for death.

Coronary artery dilation associated with bicuspid and unicuspid aortic valve disease in children: a series of 17 patients

Coronary artery dilation associated with bicuspid/unicuspid aortic valves is described in adults with limited data in children. We aimed to describe the clinical course of children with bicuspid/unicuspid aortic valves and coronary dilation including coronary Z-score changes over time, association of coronary changes with aortic valve anatomy/function, and complications. Institutional databases were searched for children ≤18 years with both bicuspid/unicuspid aortic valves and coronary dilation (1/2006-6/2021). Kawasaki disease and isolated supra-/subvalvar aortic stenosis were excluded. Statistics were descriptive with associations measured by Fisher's exact test and overlapping 83.7% confidence intervals. Of 17 children, bicuspid/unicuspid aortic valve was diagnosed at birth in 14 (82%). Median age at coronary dilation diagnosis was 6.4 years (range: 0-17.0). Aortic stenosis was present in 14 (82%) [2 (14%) moderate, 8 (57%) severe]; 10 (59%) had aortic regurgitation; 8 (47%) had aortic dilation. The right coronary was dilated in 15 (88%), left main in 6 (35%), and left anterior descending in 1 (6%) with no relationship between leaflet fusion pattern or severity of aortic regurgitation/stenosis on coronary Z-score. Follow-up evaluations were available for 11 (mean 9.3 years, range 1.1-14.8) with coronary Z-scores increasing in 9/11 (82%). Aspirin was used in 10 (59%). There were no deaths or coronary artery thrombosis. In children with bicuspid/unicuspid aortic valves and coronary dilation, the right coronary artery was most frequently involved. Coronary dilation was observed in early childhood and frequently progressed. Antiplatelet medication use was inconsistent, but no child died nor developed thrombosis.

Aortic valve repair in the pediatric population: emerging role of aortic valve neocuspidization (AVNeo procedure).

Management of aortic valve diseases in children is challenging owing to the quality and quantity of the native tissue for repair, limitations in the currently available biological materials to supplement the repair and to achieve a long-lasting durable repair in an annulus where there is still growth potential. The aortic valve neocuspidization (AVNeo) procedure has emerged as a versatile alternative strategy in the armamentarium of pediatric aortic valve reconstructions that are currently available. In this review article, the focus of the discussion will be on the various aortic valve repair procedures in the pediatric population, with a special emphasis on the emerging role of AVNeo procedure in pediatrics and its outcomes.

Autograft Stabilization for the Ross Procedure in Children

Aortic valve disease in children presents a considerable surgical challenge. When repair is not feasible, the Ross procedure represents the best option for replacement as it allows growth and does not require anticoagulation. However, there is a risk of progressive autograft dilatation, and eventual failure of the autograft with severe regurgitation. Autograft stabilization has proven beneficial in adults but has not been widely adopted in children undergoing the Ross procedure. We present a series of techniques for autograft stabilization which can be used at different stages of development, from infants to fully grown adolescents. Aortic valve disease in children presents a considerable surgical challenge. When repair is not feasible, the Ross procedure represents the best option for replacement as it allows growth and does not require anticoagulation. However, there is a risk of progressive autograft dilatation, and eventual failure of the autograft with severe regurgitation. Autograft stabilization has proven beneficial in adults but has not been widely adopted in children undergoing the Ross procedure. We present a series of techniques for autograft stabilization which can be used at different stages of development, from infants to fully grown adolescents.

P054 Acute articular rheumatism at the Hassan II hospital center, Fez, Morocco (prospective study: about 152 cases)

Abstract Background Acute Articular Rheumatism (AAR) is a major public health problem in developing countries, due to the high prevalence of its main complication, which is rheumatic heart disease. The objective of this study is to determine the clinical and biological manifestations of rheumatic fever in children at CHU Hassan II in Fez, Morocco. Methods This is a prospective study carried out from January 2016 to July 2019 in the cardiopediatric unit of CHU Hassan II in Fez. Included were patients below 18 years of age. 152 children with RAA are diagnosed according to the modified Jones criteria. The patients are classified into 2 groups: group 1: RAA with carditis and group 2: RAA without carditis. Patient data is collected on operating sheets. Statistical analysis was performed using SPSS v 21 software. Results The average age of the patients was 12 years and 10 months. The male/female sex ratio was 0.7. The most represented age group was between 5 and 15 years (76.16%). Patients of urban origin presented 78.8%. The majority of children who are diagnosed with AAR with and without cardiac involvement are admitted in winter and fall respectively. A family history of RAA was found in 1 patient and recurrent tonsillitis were mentioned in 68.42%. Cardiac involvement is found in 78.3% of patients. Arthritis was the most common major end point in patients with and without carditis (24.4% and 12.1% respectively). Arthralgia was the most common minor outcome in these patients (67.2% and 78.8% respectively). Penicillin A was the most prescribed antibiotic in the two groups (80.83% and 79.31% respectively). The predominant valve disease in children with cardiac involvement is mitral leakage (69%). Serological proof of a streptococcal infection (ASLO&amp;gt; 300U/ml) was found in 37.2% of cases. A high biological inflammatory syndrome (ESR&amp;gt; 20) was noted in 29.4%. Corticosteroid therapy was used in 42.8% of patients with carditis and in 30.3% of patients without carditis. There was a recurrence in surveillance, this is an aggravation of the mitral leakage with in an 11-year-old boy. 6 patients (3.9%) underwent valve replacement: 4 valve replacements (mitral or aortic) and two double valve replacements (mitral and aortic). One death is noted, a form of acute carditis. Conclusion Cardiac involvement was very common in our series, which shows that AAR still remains a public health problem in our country. Keywords RAA, child, cardiac involvement

Multicentre comparative analysis of long-term outcomes after aortic valve replacement in children

ObjectiveThe ideal valve substitute for surgical intervention of congenital aortic valve disease in children remains unclear. Data on outcomes beyond 10–15 years after valve replacement are limited but important for...

Abstract 14888: Extracellular Matrix Quantification of Fully Regenerated Neochorade After Bio-scaffold Mitral Valve Implantation in a Juvenile Non-human Primate Model

Introduction: To investigate enhanced treatment options for critical mitral valve disease in children, we implanted a bio-scaffold mitral valve comprising of porcine small intestinal submucosa (PSIS) in a juvenile baboon model. Hypothesis: New tissue formation would be accelerated at physical connections between the replacement bio-scaffold valve and native cardiac tissues, due to direct extracellular matrix (ECM) communications. Methods: Juvenile baboons (n=2) were implanted with a hand-made bicuspid PSIS (Cormatrix, Roswell, GA) mitral valve. The PSIS valves were excised at 11- and 20-months post-implantation. Images of histological stains (Movat’s Pentachrome; Alizée Pathology, Inc., Thurmont, MD) were subsequently spatially mapped for ECM quantification (MATLAB; Mathworks, Natick, MA). Results: PSIS bio-scaffold mitral valves (11- and 20-months post-implantation) facilitated complete regeneration of neochordae. The neochordae seamlessly integrated into the papillary muscles and left ventricular insertion sites ( Figure 1A, E ). We also found that with an increase in implantation duration of ~ 9 months, the collagen, proteoglycan and elastin content (per mm 2 ; Figure 1B-D, F-H ) had a fold-change of 6.96, 18.42 and 4.94, respectively. Conclusions: Our findings suggest that the PSIS bio-scaffold mitral valve apparatus can regenerate neochordae without the need for any biochemical or biomechanical treatment. Nonetheless, other valve spatial areas of importance (e.g. leaflets) will require additional strategies. As a next step, we will produce oscillatory flow-conditioned, stem cell-derived ECM, to accelerate tissue regeneration. The mechanical parameters that we computed to permit physiological oscillatory flow conditions are an oscillatory shear index (OSI) of 0.23 and time averaged bio-scaffold shear stress (TAB-SSS) of 4.6 dynes/cm 2 . Acknowledgements: AHA Award ID: 16GRNT31090009; The Miami Research Heart Institute; FIU-UGS DYF.

The utility of aortic valve leaflet reconstruction techniques in children and young adults

ObjectivesThe treatment of aortic valve disease in children and adolescents requires an individualized approach to provide a long-term solution with optimal hemodynamic profile. The role of aortic leaflet reconstruction techniques is evolving. MethodsWe retrospectively reviewed the charts of 58 patients who underwent aortic valve tricuspidalization either by an Ozaki procedure (neo-tricuspidalization) or single leaflet reconstruction between 2015 and 2019. Immediate operative results as well as hospital and short-term outpatient follow-up data were evaluated. ResultsFifty-eight patients underwent leaflet reconstruction with 40 (69%) receiving a neo-tricuspidalization and 18 patients (31%) undergoing single leaflet reconstruction, using either a glutaraldehyde fixed autologous pericardium or tissue engineered bovine pericardium (CardioCel; Admedus, Queensland, Australia). The median age at the time of surgery was 14.8 years (interquartile range, 10.6-16.8 years). Twenty-three patients (40%) had isolated aortic regurgitation. The peak velocity across the aortic valve decreased from 3.4 ± 1.2 meters per second (m/s) preoperatively to 2.0 ± 0.4 m/s (P < .001) after surgery and remained stable (2.2 ± 0.7 m/s) during a median echocardiographic follow-up of 14.1 months (7.2-20.1 months) for the whole cohort. Freedom from reoperation or moderate and greater aortic regurgitation at 1, 2, and 3 years was 94.2% ± 3.3%, 85.0% ± 5.8%, and 79.0% ± 8.0%, respectively, with no difference between the neo-tricuspidalization and single leaflet reconstruction groups (P = .635). There were 6 late reoperations (10%) of which 3 were due to endocarditis. ConclusionsAortic leaflet reconstruction provides acceptable short-term hemodynamic outcomes and proves the utility of this technique as an adjunctive strategy for surgical treatment of aortic valve disease in children and young adults.

Outcome of 40 consecutive cases of modified Ross procedure using novel Dacron valved conduit.

The Ross procedure is an established option for aortic valve disease in children. Due to limited availability of pulmonary homograft, we devised a novel technique for right ventricular outflow tract (RVOT) reconstruction by preparing indigenous Dacron valved conduit. Forty consecutive cases of modified Ross procedure done at our center (2013-2018) were analyzed. Thirty-seven patients (95%) were followed up with median duration of 2.5 (0.08-5.5) years. Median age was 12 (5-39) years. Nineteen (47.5%) patients had rheumatic aortic valve disease, while 19 (47.5%) had congenital aortic valve disease. Aortic root replacement with pulmonary autograft was performed in all patients. Dacron conduit for RVOT reconstruction was used with on table sewn bileaflet valve using Dacron patch (n = 22), expanded polytetrafluoroethylene (ePTFE) membrane (n = 10), bioprosthetic valve (n = 4), and pericardium (n = 4). Additional surgical procedures included mitral valve repair (n = 10), septal myectomy (n = 2), ascending aorta replacement (n = 1), ruptured sinus of valsalva (RSOV) repair (n = 1), and ventricular septal defect (VSD) closure (n = 1). There was one in-hospital mortality while one late death occurred at 3.5years postoperatively. The neo-aortic valve regurgitation on echocardiographic evaluation at last follow-up was trivial (n = 28), mild (n = 7), and moderate (n = 2). Mild RVOT obstruction was present in 8 patients while 18 patients had mild pulmonary regurgitation. No patient required reintervention during follow-up. Our early results of modified Ross procedure are encouraging, however, long-term follow-up is required.

Progress of surgical treatment for aortic valve diseases in children

As the primary treatment of aortic valve stenosis in children, surgical aortic valvotomy (SAV) and balloon aortic valvuloplasty (BAV) are widely used. With the similar early curative effect to BAV, SAV performs better in long-term follow-up. But the first choice for aortic valve stenosis is still controversial. These years, aortic valve repair is valued and different repair techniques have been reported and achieved good results. The complex repair techniques, as leaflet extension, leaflet replacement or valve reconstruction, are effective in treating diseased valves that cannot be repaired before. Ozaki technology, using glutaraldehyde-treated autologous pericardium to replace the aortic valve, makes the surgery more standardized and reproducible by developing special instruments. Pulmonary autograft (Ross procedure) is considered to be superior to other valve replacement technologies due to the good hemodynamic performance and lower reoperation rate. Mechanical valve is still used in some cases, but the quality of life is low due to the lifelong anticoagulation, and it has a high reintervention rate. The biological valve has been rarely used in children because of its high rate of early calcification and structural failure.

Current surgical strategies and techniques of aortic valve diseases in children.

While the long-term outcome of surgical aortic valvotomy (SAV) appears to be better than that of balloon aortic valvuloplasty (BAV) as the primary procedure of aortic valve stenosis, the surgical strategies and techniques of treating aortic valve disease in children in other situations remain controversial. Valve repair should be first considered while replacement is still unavoidable in some cases, and new repair techniques developed by innovative surgeons are gradually becoming adopted. Some complex repair procedures such as cusp extension, leaflet replacement/reconstruction have provided satisfactory outcomes. The Ozaki technique replaces aortic valve leaflets with glutaraldehyde-treated autologous pericardium instead of replacing the valve entirely. Special instruments have been developed to make the Ozaki technique more reproducible and standardized. Neonates and infants undergoing aortic valve replacement (AVR) are a high-risk group, where repair should be the primary consideration rather than replacement. Several systematic reviews reveal that all currently available aortic valve substitutes such as pulmonary autograft, mechanical prosthesis, homograft and bioprosthesis are associated with suboptimal results in children, but pulmonary autograft appeared to be superior with high freedom from reintervention and better hemodynamic performance. The strategy for treatment of aortic valve disease should be specifically analyzed based on the brief of being beneficial for children.

Mid-term Outcome of 100 Consecutive Ross Procedures: Excellent Survival, But Yet to Be a Cure.

The Ross procedure offers excellent short-term outcome but the long-term durability is under debate. Reinterventions and follow-up of 100 consecutive patients undergoing Ross Procedure at our centre (1993-2011) were analysed. Follow-up was available for 96 patients (97%) with a median duration of 5.3 (0.1-17.1) years. Median age of the patient cohort was 15.2 (0.04-58.4) years with 76 males. 93% had underlying congenital aortic stenosis. Root replacement technique was applied in all. The most common valved conduits used for reconstruction of the right ventricular outflow tract were homografts (66 patients) and bovine jugular vein (ContegraR) graft (31 patients). Additional procedures included Ross-Konno procedure (14%), resection of subaortic stenosis/myectomy (11%) and reduction plasty of the ascending aorta (25%). One patient died within the first 30days (1%). Late deaths occurred in 4 patients (4%) 0.5-4.5years postoperatively: causes included pulmonary hypertension due to endocardial fibroelastosis (2), subarachnoid haemorrhage (1) and sudden cardiac death (1). Five-year survival was 93.6 (95% CI 88.1-99.1)%. Moderate or severe aortic (autograft) regurgitation needing reoperation occurred in 8 patients with a 5-year freedom from autograft reoperation of 98.5 (95.6-100)%. Five-year freedom from reintervention (surgery or catheter based) on the right ventricular outflow tract conduit was 91.5 (85.5-96.5)%. Univariate predictors of this reinterventions were smaller graft size (p = 0.03) and use of a ContegraR graft (p = 0.04). Ross procedure can be performed with low mortality and good survival in the long term. Most of the reinterventions are related to the neo-right ventricular outflow tract and may be partly attributed to the lack of growth. While the Ross Procedure remains an invaluable option for aortic valve disease in children, new solutions for the neo-pulmonary valve as well as for the less often occurring problems on the autograft are needed.

Handmade Trileaflet Valve Design and Validation for Pulmonary Valved Conduit Reconstruction Using Taguchi Method and Cascade Correlation Machine Learning Model

Pulmonary valve diseases in children and adults include different degrees of stenosis, regurgitation, or congenital defects. Valve repair or replacement surgery is used to treat valvular dysfunction and to improve regurgitations flow for pulmonary valve pathologies. Handmade trileaflet valve designs with different ranges of diameters have been used for pulmonary valved conduit reconstruction among children or adult patients with available conditions. In this paper, we propose a multiple regression model as a cascade-correlation-network-based estimator to determine optimal trileaflet parameters, including width, length, and upper/lower curved structures, for trileaflet valve reconstruction. The diameter of the main pulmonary artery is determined via computed tomography pulmonary angiography, and a trileaflet valve template is rapidly sketched. The actual valve is constructed using an expanded polytetrafluoroethylene material. Using an experimental pulmonary circulation loop system, design parameters and valve efficacy can be validated by the Taguchi method through calculation of signal-to-noise ratios. Experimental results indicate that in contrast to commercial valve stents, the handmade trileaflet valve exhibits good performance and is a valuable option in treatment of severe pulmonary regurgitation.

Echocardiographic assessment of pediatric semilunar valve disease.

We reviewed echocardiography literature for the assessment and management of semilunar valve disease in children. A search was performed within the National Library of Medicine using the keywords aortic stenosis (AS), aortic regurgitation, pulmonary stenosis (PS), and pulmonary regurgitation in children. The search was further refined adding the keywords-pediatric, neonates, echocardiographic definition, classification, evaluation. Thirty-eight studies were included. For stenotic lesions, there were sufficient consistencies between Doppler and invasive gradients (especially for PS), while other quantitative parameters used in adults showed significant limitations when applied to children. Heterogeneities remain in the range of Doppler measurements utilized to define mild vs moderate vs severe AS/PS, and to guide management. There is sufficient consensus regarding indications for interventions. In regurgitant lesions, there is weak evidence supporting the use of quantitative or semiquantitative parameters after correction for body surface area; clear indications for intervention are lacking. Because adult echocardiographic recommendations cannot be simply translated to the pediatric age, more specific pediatric guidelines and standards for the assessment of semilunar valve disease are needed.

LONG TERM RESULTS OF PAEDIATRIC ROSS PROCEDURE: A NEW METHODOLOGY OF TIME-TO-EVENT DATA META-ANALYSIS

Ross procedure has been used for over 40 years in the surgical management of irreparable aortic valve disease in children. Little clinical long-term information is available regarding the durability of the autograft in the aortic position and the pulmonary conduit substitute. Moreover, there is no fully established methodology to perform time-to-event data meta-analysis. The aim of study was to develop a new methodology to perform such meta-analysis and therefore pool the long term results of paediatric Ross procedure.

Biomechanics drive histological wall remodeling of neoaortic root: A mathematical model to study the expression levels of ki 67, metalloprotease, and apoptosis transition.

The pulmonary artery autograft (PA) is the ideal substitute for aortic valve disease in children and young adult. However, it is harnessed by the issue of long-term dilation and regurgitation, often requiring surgery. PA implanted in aortic position during the growth phase in children undergoes a process of mechanical remodeling. We previously developed a semiresorbable armored prosthesis able to mechanically sustain the neoaorta preventing dilation and to gradually integrate with the PA wall inducing a progressive arterial-like tissue positive remodeling. We also described the mechanisms of growth, remodeling and stress shielding of the reinforced PA through a mathematical model. We sought to demonstrate the biological counterpart and the potential molecular mechanisms underlying this histological and mechanical remodeling. A specific mathematical model was developed to describe mechanical behavior of the PA. Mallory trichrome red staining and immunohistochemistry for MMP-9 were performed to elucidate extracellular matrix remodeling phenomena. Apoptosis and cell proliferation were determined by TUNEL assay and immunohistochemistry for Ki67, respectively. An histological remodeling phenomenon sustained by increased level of MMP-9, augmented cell proliferation and reduced apoptosis in the reinforced PA was demonstrated. The mathematical model predicted the biomechanical behavior subtended by the histological changes of the PA in these settings. Changes in metalloproteinases (MMP-9), cell proliferation and apoptosis are the main actors in the remodeling process occurring after transposition of the PA into systemic regimens. Use of semiresorbable reinforcements might induce a positive remodeling of the PA in the context of Ross operation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2785-2793, 2016.