Neoaortic root diameters and aortic regurgitation in children after the Ross operation

Bicuspid Aortic Valve in Children and Young Adults for Cardiologists and Cardiac Surgeons: State-of-the-Art of Literature Review

Bicuspid aortic valve disease is the most prevalent congenital heart disease, affecting up to 2% of the general population. The presentation of symptoms may vary based on the patient's anatomy of fusion, with transthoracic echocardiography being the primary diagnostic tool. Bicuspid aortic valves may also appear with concomitant aortopathy, featuring fundamental structural changes which can lead to valve dysfunction and/or aortic dilatation over time. This article seeks to give a comprehensive overview of the presentation, treatment possibilities and long-term effects of this condition. The databases MEDLINE, Embase, and the Cochrane Library were searched using the terms "endocarditis" or "bicuspid aortic valve" in combination with "epidemiology", "pathogenesis", "manifestations", "imaging", "treatment", or "surgery" to retrieve relevant articles. We have identified two types of bicuspid aortic valve disease: aortic stenosis and aortic regurgitation. Valve replacement or repair is often necessary. Patients need to be informed about the benefits and drawbacks of different valve substitutes, particularly with regard to life-long anticoagulation and female patients of childbearing age. Depending on the expertise of the surgeon and institution, the Ross procedure may be a viable alternative. Management of these patients should take into account the likelihood of somatic growth, risk of re-intervention, and anticoagulation risks that are specific to the patient, alongside the expertise of the surgeon or centre. Further research is required on the secondary prevention of patients with bicuspid aortic valve (BAV), such as lifestyle advice and antibiotics to prevent infections, as the guidelines are unclear and lack strong evidence.

Long-term autograft dilation and durability after the Ross procedure are similar in infants, children, and adolescents with primary aortic stenosis

BACKGROUND

Autograft durability and remodeling are thought to be superior in younger pediatric patients after the Ross operation. We sought to delineate the fate of autografts across the pediatric age spectrum in patients with primary aortic stenosis (AS).

METHODS

We retrospectively reviewed patients age ≤18 years with primary AS who underwent the Ross operation between 1993 and 2020. Patients were categorized by age. The primary endpoint was autograft dimensional change, and secondary endpoints were severe neo-aortic insufficiency (AI) and autograft reintervention.

RESULTS

A total of 119 patients underwent the Ross operation, including 37 (31.1%) in group I (age <18 months), 24 (20.2%) in group II (age 18 months-8 years), and 58 (48.7%) in group III (age 8-18 years). All groups exhibited similar annular growth rates within the first 5 postoperative years, followed by a collective decrease in annulus growth rates from year 5 to year 10. Group III experienced rapid sinus dilation in the first 5 years, followed by stabilization of the sinus z-score from year 5 to year 10, whereas groups I and II demonstrated stable sinus z-scores over 10 years. There were 4 early deaths (3.4%) and 2 late deaths (1.7%) at a median follow-up of 8.1 years (range, 0.01-26.3 years). At 15 years, the incidences of severe neo-AI (0.0 ± 0.0% vs 0.0 ± 0.0% vs 3.9 ± 3.9%; P = .52) and autograft reintervention (8.4 ± 6.0% vs 0.0 ± 0.0% vs 2.4 ± 2.4%; P = .47) were similar in the 3 groups.

CONCLUSIONS

Age at the time of Ross operation for primary AS does not influence long-term autograft remodeling or durability. Other physiologic or technical factors are likely greater determinants of autograft fate.

Biomechanics of Pulmonary Autograft as Living Tissue: A Systematic Review

Introduction: The choice of valve substitute for aortic valve surgery is tailored to the patient with specific indications and contraindications to consider. The use of an autologous pulmonary artery (PA) with a simultaneous homograft in the pulmonary position is called a Ross procedure. It permits somatic growth and the avoidance of lifelong anticoagulation. Concerns remain on the functionality of a pulmonary autograft in the aortic position when exposed to systemic pressure. Methods: A literature review was performed incorporating the following databases: Pub Med (1996 to present), Ovid Medline (1958 to present), and Ovid Embase (1982 to present), which was run on 1 January 2022 with the following targeted words: biomechanics of pulmonary autograft, biomechanics of Ross operation, aortic valve replacement and pulmonary autograph, aortic valve replacement and Ross procedure. To address the issues with heterogeneity, studies involving the pediatric cohort were also analyzed separately. The outcomes measured were early- and late-graft failure alongside mortality. Results: a total of 8468 patients were included based on 40 studies (7796 in pediatric cohort and young adult series and 672 in pediatric series). There was considerable experience accumulated by various institutions around the world. Late rates of biomechanical failure and mortality were low and comparable to the general population. The biomechanical properties of the PA were superior to other valve substitutes. Mathematical and finite element analysis studies have shown the potential stress-shielding effects of the PA root. Conclusion: The Ross procedure has excellent durability and longevity in clinical and biomechanical studies. The use of external reinforcements such as semi-resorbable scaffolds may further extend their longevity.

The effectiveness and safety of pulmonary autograft as living tissue in Ross procedure: a systematic review

Background

Reports on effectiveness and safety after the implant of pulmonary autograft (PA) living tissue in Ross procedure, to treat both congenital and acquired disease of the aortic valve and left ventricular outflow tract (LVOT), show variable durability results. We undertake a quantitative systematic review of evidence on outcome after the Ross procedure with the aim to improve insight into outcome and potential determinants.

Methods

A systematic search of reports published from October 1979 to January 2021 was conducted (PubMed, Ovid Medline, Ovid Embase and Cochrane library) reporting outcomes after the Ross procedure in patients with diseased aortic valve with or without LVOT. Inclusion criteria were observational studies reporting on mortality and/or morbidity after autograft aortic valve or root replacement, completeness of follow-up >90%, and study size n≥30. Forty articles meeting the inclusion criteria were allocated to two categories: pediatric patient series and young adult patient series. Results were tabulated for a clearer presentation.

Results

A total of 342 studies were evaluated of which forty studies were included in the final analysis as per the eligibility criteria. A total of 8,468 patients were included (7,796 in pediatric cohort and young adult series and 672 in pediatric series). Late mortality rates were remarkably low alongside similar age-matched mortality with the general population in young adults. There were differences in implantation techniques as regard the variability in stress and the somatic growth that recorded conflicting outcomes regarding the miniroot vs the subcoronary approach.

Discussion

The adaptability of lung autograft to allow for both stress variability and somatic growth make it an ideal conduit for Ross's operation. The use of the miniroot technique over subcoronary implantation for better adaptability to withstand varying degrees of stress is perhaps more applicable to different patient subgroups.

The Ross/Ross-Konno procedure in infancy is a safe and durable solution for aortic stenosis

OBJECTIVE

The objective of this study was to characterize early and midterm outcomes after the Ross/Ross-Konno procedure performed in infancy for severe aortic valve disease.

METHODS

Between January 1995 and December 2018, 35 infants younger than 1 year (13 neonates) underwent a Ross/Ross-Konno procedure. Patients were followed up to a median of 4.1 years (interquartile range [IQR], 2.6-9.5). Primary outcome measures were survival, early morbidity, freedom from reintervention and long-term functional and echocardiographic status.

RESULTS

Median age at operation was 49 days (IQR, 17-135) and weight was 4 kg (IQR, 3.4-5.2). Thirty-one (89%) had undergone a previous procedure, including balloon valvuloplasty in 26 (74%). Thirty (86%) required annular enlargement (Konno incision). Five required concomitant aortic arch surgery (2 neonates, 3 infants). There were no early deaths, and 1 late death at 18 months. Freedom from reoperation was 85% (95% confidence interval [CI], 68%-93%) at 1 year, 76% (95% CI, 54%-88%) at 5 years, and 62% (95% CI, 36%-79%) at 10 years. One modified Konno was performed at 5 years after a Ross in infancy. Ten right ventricle to pulmonary artery conduits have required reintervention (2 percutaneous pulmonary valve implantations). One child required a permanent pacemaker for complete heart block. At latest follow-up, 32 (94%) of 34 survivors were asymptomatic. There was no significant change in neoaortic Z-scores between 6 weeks and latest follow-up.

CONCLUSIONS

The neonatal and infant Ross/Ross-Konno procedure can be performed with low mortality and achieves a stable left ventricular outflow tract. Significant early morbidity reflects the preoperative condition of the patients but definitive surgery of this type can be considered as a primary approach.

The Choice of Pulmonary Autograft in Aortic Valve Surgery: A State-of-the-Art Primer

The Ross procedure has long been seen as an optimal operation for a select few. The detractors of it highlight the issue of an additional harvesting of the pulmonary artery, subjecting the native PA to systemic pressures and the need for reintervention as reasons to avoid it. However, the PA is a living tissue and capable of adapting and remodeling to growth. We therefore review the current evidence available to discuss the indications, contraindications, harvesting techniques, and modifications in a state-of-the-art narrative review of the PA as an aortic conduit. Due to the lack of substantial well-designed randomized controlled trials (RCTs), we also highlight the areas of need to reiterate the importance of the Ross procedure as part of the surgical armamentarium.

[Prosthetic repair of aortic valve cusps with autopericardium in children. State of the art and prospects]

According to the results of modern researchers, the main techniques used in congenital pathology of the aortic valve in children include balloon catheter dilatation of the aortic valve, surgical valvuloplasty, the Ross procedure and replacement of the aortic valve with a mechanical prosthesis. Many surgeons point out that these techniques in congenital pathology of the aortic valve yield suboptimal results. This is often due to the lack of a clear-cut definition between surgeons as to what operation should be performed in a particular age group. According to the reports of the majority of researchers, biological prostheses undergo early degeneration and structural changes in paediatric cardiac surgery and yield the worst results. Comparing the main techniques, optimal haemodynamics is observed after the Ross procedure. A disadvantage of this operation is the necessity of repeat intervention on the right ventricular outflow tract, which is required in 20 to 40%. Concomitant surgery of the mitral valve and/or aortic arch during the Ross procedure significantly increases the lethality and the risk of postoperative complications. Compared with an adult cohort of patients, children after prosthetic repair of the aortic valve using a mechanical prosthesis are more often found to have postoperative complications and a higher mortality rate. Yet another problem encountered in paediatric valve surgery is the unavailability of commercial prostheses sized ?19 mm. The duration of the intraoperative parameters for reconstructions of the aortic valve, the Ross procedure, and replacement of the aortic valve by the results of many studies averagely amounts to 74±34 min, 100±56 min, and 129±71 min, respectively. Yet another method which can be used for neocuspidization of the aortic valve in reconstructive surgery of the aortic root in paediatric patients is the use of glutaraldehyde-treated autologous pericardium. In our opinion, given the simplicity of the procedure, duration of the intraoperative parameters, and acceptable initial results reported by some researchers, the Ozaki procedure may be performed in children.

Subcoronary Ross/Ross-Konno operation in children and young adults: initial single-centre experience

OBJECTIVES

We sought to evaluate the outcome after modified subcoronary Ross/Ross-Konno operation in children and young adults.

METHODS

Between January 2013 and January 2019, a total of 50 patients with median age of 6.3 years (range 0.02-36.5 years, 58% males), including 10 infants (20%), received modified subcoronary Ross/Ross-Konno operation at our institution. Survival, morbidity, reinterventions, aortic valve function and aortic root dimensions were analysed.

RESULTS

At a median follow-up of 31.2 months (range 14.4-51 months), there were 1 early death and 1 late death, both in the infant group. The overall survival at 5 years after the operation was 95%. Two patients needed aortic valve replacement, 11 and 15 months after their Ross operation. At 5 years, freedoms from reoperation on the autograft and on the right ventricle to pulmonary artery conduit were 94% and 97%, respectively. Freedom from aortic valve regurgitation greater than mild was 97% at 5 years. Median dimensions of the aortic root at all levels remained in normal range at last visit. Forty-four patients (95%) were in New York Heart Association class I with normal left ventricular function.

CONCLUSIONS

The initial experience with the subcoronary Ross/Ross-Konno operation in children and young adults showed excellent outcome. The mortality and morbidity among infants remain significant. The described technique is reproducible and might be advantageous in situations when prosthetic supporting techniques interfere with somatic growth.

Finite Element Analysis Investigate Pulmonary Autograft Root and Leaflet Stresses to Understand Late Durability of Ross Operation

Ross operation might be a valid option for congenital and acquired left ventricular outflow tract disease in selected cases. As the pulmonary autograft is a living substitute for the aortic root that bioinspired the Ross operation, we have created an experimental animal model in which the vital capacity of the pulmonary autograft (PA) has been studied during physiological growth. The present study aims to determine any increased stresses in PA root and leaflet compared to the similar components of the native aorta. An animal model and a mathematical analysis using finite element analysis have been used for the purpose of this manuscript. The results of this study advance our understanding of the relative benefits of pulmonary autograft for the management of severe aortic valve disease. However, it launches a warning about the importance of the choice of the length of the conduits as mechanical deformation, and, therefore, potential failure, increases with the length of the segment subjected to stress. Understanding PA root and leaflet stresses is the first step toward understanding PA durability and the regions prone to dilatation, ultimately to refine the best implant technique.

Biomechanical future of the growing pulmonary autograft in Ross operation

It has been few years since the preliminary translational research study on mechanics performance of autologous pulmonary tissue were published to circumvent complication relies to SVD. Several studies reported the modification of pulmonary native autograft root subjected to dynamic stress strain in long-term outcomes of aortic valve replacement. Our multidisciplinary research team firstly describe the weave relationship between stress-strain, growth and remodelling in an experimental model of Ross Operation. From a biomechanical point of view, the rapid absorption of polydioxanone constituting the internal part of the device may limit the potential negative effect of excessive stretching and improvement of steeper curve in the circumferential response. Improvement of longitudinal stretching of pulmonary autograft by external component of device are indicative of auxetic effect of e-PTFE. Successful reinforcement with semiresorbable device can also be favourable to pulmonary autograft function in growing patients needing to match somatic growth. The attendant decrease in PA expansion and the preserved features of the valve leaflets enhances durability of Ross operation. Strengthening of the distal pulmonary root anastomosis using external reinforcement, modifying the ascending phase of the circumferential stress curve, might be advisable as previously described. PA is an ideal substitute for aortic valve replacement not only in Mr. Ross's dreams but also from the biomechanical point of view.

Ross operation 23 years after surgery: It should not be a "forgotten" option

INTRODUCTION

The Ross procedure plays a pivotal part in both congenital and acquired diseases of the aortic valve, especially in young patients. The advantages of this procedure are widely known; however, long-term studies have shown dilation of the pulmonary autograft (PA) in up to 20% of patients in the second decade postoperatively.

METHODS

Three cases (ages 38, 51, and 53) who underwent the Ross procedure 23 years ago for bicuspid valves and endocarditis. Cases were followed-up with echocardiogram and computed tomography scan with three-dimensional reconstructions.

RESULTS

The PA showed normal function with favorable geometry alongside the thoracic aorta, while the pulmonary homograft preserved its function with a low degree of calcification. The mean annual expansion of the autograft was only 0.15, 0.30, and 0.40 mm with no pathological dilation after 20 years DISCUSSION: Ross operation provides excellent hemodynamic results while avoiding long-term anticoagulation and might constitute a valid adjunct in selected categories such as young or endocarditis patients.

Simulating the ideal geometrical and biomechanical parameters of the pulmonary autograft to prevent failure in the Ross operation

OBJECTIVES

Reinforcements for the pulmonary autograft (PA) in the Ross operation have been introduced to avoid the drawback of conduit expansion and failure. With the aid of an in silico simulation, the biomechanical boundaries applied to a healthy PA during the operation were studied to tailor the best implant technique to prevent reoperation.

METHODS

Follow-up echocardiograms of 66 Ross procedures were reviewed. Changes in the dimensions and geometry of reinforced and non-reinforced PAs were evaluated. Miniroot and subcoronary implantation techniques were used in this series. Mechanical stress tests were performed on 36 human pulmonary and aortic roots explanted from donor hearts. Finite element analysis was applied to obtain high-fidelity simulation under static and dynamic conditions of the biomechanical properties and applied stresses on the PA root and leaflet and the similar components of the native aorta.

RESULTS

The non-reinforced group showed increases in the percentages of the mean diameter that were significantly higher than those in the reinforced group at the level of the Valsalva sinuses (3.9%) and the annulus (12.1%). The mechanical simulation confirmed geometrical and dimensional changes detected by clinical imaging and demonstrated the non-linear biomechanical behaviour of the PA anastomosed to the aorta, a stiffer behaviour of the aortic root in relation to the PA and similar qualitative and quantitative behaviours of leaflets of the 2 tissues. The annulus was the most significant constraint to dilation and affected the distribution of stress and strain within the entire complex, with particular strain on the sutured regions. The PA was able to evenly absorb mechanical stresses but was less adaptable to circumferential stresses, potentially explaining its known dilatation tendency over time.

CONCLUSIONS

The absence of reinforcement leads to a more marked increase in the diameter of the PA. Preservation of the native geometry of the PA root is crucial; the miniroot technique with external reinforcement is the most suitable strategy in this context.

Neo-aortic insufficiency late after staged reconstruction for hypoplastic left heart syndrome: impact of differences in initial palliative procedures

The neo-aortic insufficiency in patients with hypoplastic left heart syndrome is an important sequela. We assessed the risks of the neo-aortic valve deterioration by the difference of initial palliations: Group I underwent primary Norwood (Nw) with systemic-to-pulmonary artery shunt (SPS), Group II underwent bilateral pulmonary artery banding (bPAB) and subsequent Nw with SPS (bPAB-Nw/SPS), Group III underwent bPAB and subsequent Nw with bidirectional Glenn (BDG) procedure (bPAB-Nw/BDG). The neo-aortic valve z score changes over time did not reach statistical significance in all groups (p = 0.43 for Group I, 0.20 for Group II, and 0.30 for Group III). The degree of neo-aortic valve insufficiency did not change significantly over time during this period except for Group III (p = 0.34 for Group I, 0.20 for Group II, and 0.02 for Group III). On the other hand, dimensions of the neo-aortic annulus and degrees of neo-aortic insufficiency did not differ significantly among the 3 groups at any pre-determined time. The presence or absence of incision into the sino-tubular junction at Nw did not affect the late neo-aortic valve z score or insufficiency. These data indicate that the difference of initial palliative procedures does not affect late neo-aortic valve insufficiency in Nw survivors. Because valve failure may develop in longer follow-up, further observation should be conducted.

Diagnosis and Management of Noncardiac Complications in Adults With Congenital Heart Disease: A Scientific Statement From the American Heart Association

Life expectancy and quality of life for those born with congenital heart disease (CHD) have greatly improved over the past 3 decades. While representing a great advance for these patients, who have been able to move from childhood to successful adult lives in increasing numbers, this development has resulted in an epidemiological shift and a generation of patients who are at risk of developing chronic multisystem disease in adulthood. Noncardiac complications significantly contribute to the morbidity and mortality of adults with CHD. Reduced survival has been documented in patients with CHD with renal dysfunction, restrictive lung disease, anemia, and cirrhosis. Furthermore, as this population ages, atherosclerotic cardiovascular disease and its risk factors are becoming increasingly prevalent. Disorders of psychosocial and cognitive development are key factors affecting the quality of life of these individuals. It is incumbent on physicians who care for patients with CHD to be mindful of the effects that disease of organs other than the heart may have on the well-being of adults with CHD. Further research is needed to understand how these noncardiac complications may affect the long-term outcome in these patients and what modifiable factors can be targeted for preventive intervention.

Pulmonary autograft in aortic position: is everything known?

The Ross operation provides several advantages compared to other valve substitutes to manage aortic valve disease, such as growth potential, excellent hemodynamics, freedom from oral anticoagulation and hemolysis, and better durability. However, progressive dilatation of the pulmonary autografts after Ross operation reflects the inadequate remodeling of the native pulmonary root in the systemic circulation, which results in impaired adaptability to systemic pressure and risk of reoperation after the first decade. A recently published article showed that remodeling increased wall thickness and decreased stiffness in the failed specimens after Ross operation, and the increased compliance might play a key role in determining the progressive long-term autograft root dilatation. Late dilatation can be counteracted by an external barrier which prevents failure. Therefore, an inclusion cylinder technique with a native aorta or a synthetic external support, such as Dacron, might stabilize the autograft root and improve long-term outcomes. In this article, we offer a prospective about the importance of biomechanical features in future developments of the Ross operation. Pre-clinical and clinical evaluations of the biomechanical properties of these reinforced pulmonary autografts might shed new light on the current debate about the long-term fate of the pulmonary autograft after Ross procedure.

The mid-term outcome of primary open valvotomy for critical aortic stenosis in early infancy - a retrospective single center study over 18 years

Background

The objective of this study was to examine early and long-term results of surgical aortic valvotomy in neonates and infants aged less than four months and to identify predictors of outcome.

Methods

Between August 1994 and April 2012, 83 consecutive patients younger than 4 months of age underwent open heart valvotomy for critical aortic stenosis in our institution. Median age was 17 days (range 0-111 days). We examined clinical records to establish determinants of outcome and illustrate long-term results.

Results

Fifty-six patients (67 %) were neonates. Associated cardiac malformations were found in 24 patients (29 %), including multilevel left heart obstruction in 5. The median follow-up was 4.2 years. The time-related survival rate was 87 and 85 % at 5 and 15 years, respectively. The time-related survival without reintervention was respectively 51, 35 and 18 % at 5, 10 and 15 years. The time-related survival without aortic valve replacement was respectively 67, 54 and 39 % at 5, 10 and 15 years. Ventricular dysfunction (p = 0.04), delayed sternal closure (p = 0.007), endocardial fibroelastosis (p = 0.02) and low z-score of the aortic annulus (p = 0.04) were found predictors of global mortality. Ventricular dysfunction (p = 0.01) and endocardial fibroelastosis (p = 0.04) were found predictors of reintervention.

Conclusions

The experience, in our center, on the management of critical aortic stenosis, shows a low early and late mortality, but the aortic valvotomy is a palliative procedure and we see unfortunately a high rate of reintervention among which the aortic valve replacement. These results suggest to reconsider the use of aortic balloon valvotomy, and particularly for the neonates with a low cardiac output in order to avoid the myocardial stress and the neurological injury due to the cardiopulmonary bypass.

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.

Stress-shielding, growth and remodeling of pulmonary artery reinforced with copolymer scaffold and transposed into aortic position

Ross operation, i.e., the use of autologous pulmonary artery to replace diseased aortic valve, has been recently at the center of a vivid debate regarding its unjust underuse in the surgical practice. Keystone of the procedure regards the use of an autologous biologically available graft which would preserve the anticoagulative and tissue homeostatic functions normally exerted by the native leaflets and would harmoniously integrate in the vascular system, allowing for progressive somatic growth of aortic structures. With this respect, recently, some of the authors have successfully pioneered a large animal model of transposition of pulmonary artery in systemic pressure load in order to reproduce the clinical scenario in which this procedure might be applied and allow for the development and testing of different devices or techniques to improve the pulmonary autograft (PA) performance, by testing a bioresorbable mesh for PA reinforcement. In the present work, to support and supplement the in vivo animal experimentation, a mathematical model is developed in order to simulate the biomechanical changes in pulmonary artery subjected to systemic pressure load and reinforced with a combination of resorbable and auxetic synthetic materials. The positive biological effects on vessel wall remodeling, the regional somatic growth phenomena and prevention of dilatative degeneration have been analyzed. The theoretical outcomes show that a virtuous biomechanical cooperation between biological and synthetic materials takes place, stress-shielding guiding the physiological arterialization of vessel walls, consequently determining the overall success of the autograft system.

A composite semiresorbable armoured scaffold stabilizes pulmonary autograft after the Ross operation: Mr Ross's dream fulfilled

OBJECTIVES

Use of resorbable external reinforcement of the pulmonary autograft during the Ross operation has been suggested, but the differential regional potential for dilation of the aorta, mainly regarding the neo-root and the neo-Valsalva sinuses, represents an unresolved issue. Auxetic materials could be useful in preventing dilation given their favorable mechanical properties. We designed a composite semiresorbable armoured bioprosthesis constituted by polydioxanone and expanded polytetrafluoroethylene and evaluated its effectiveness as a pulmonary autograft reinforcement device in an animal model of the Ross procedure.

METHODS

An experimental model of the Ross procedure was performed in 20 three-month-old growing lambs. The pulmonary autograft was alternatively nonreinforced (control group n = 10) or reinforced with composite bioprosthesis (reinforced group n = 10). Animals were followed up during growth for 6 months by angiography and echocardiography. Specific stainings for extracellular matrix and immunohistochemistry for metalloproteinase-9 were performed.

RESULTS

Reference aortic diameter increased from 14 ± 1 mm to 19 ± 2 mm over 6 months of growth. In the control group, pulmonary autograft distension (28 ± 2 mm) was immediately noted, followed by aneurysm development at 6 months (40 ± 2 mm, P < .001 vs reference). In the reinforced group, an initial dilation to 18 ± 1 mm was detected and the final diameter was 27 ± 2 mm (42% increase). Two deaths due to pulmonary autograft rupture occurred in the control group. On histology, the control group showed medial disruption with connective fibrous replacement, whereas in the reinforced group compensatory intimal hyperplasia was present in the absence of intimal tears. The bioprosthesis promoted a positive matrix rearrangement process favoring neoarterialization and elastic remodeling as demonstrated on specific staining for elastin collagen and metalloproteinase-9.

CONCLUSIONS

The device adapted and functionally compensated for the characteristics of autograft growth, guaranteeing a reasonable size of the autograft at 6 months, but more important, because the device is biocompatible, it did not disrupt the biological process of growth or cause inflammatory damage to the wall.

Aortopathy associated with congenital heart disease: A current literature review

In patients born with congenital heart disease, dilatation of the aorta is a frequent feature at presentation and during follow-up after surgical intervention. This review provides an overview of the pathologies associated with aortopathy, and discusses the current knowledge on pathophysiology, evolution, and treatment guidelines of the aortic disease associated with congenital heart defects.

An experimental model of the Ross operation: Development of resorbable reinforcements for pulmonary autografts

OBJECTIVES

To circumvent the issue of pulmonary autograft (PA) dilation after the Ross procedure, surgical reinforcement strategies have been suggested in clinical or anecdotal series. However, no preclinical large-animal model of the Ross procedure is available, which is needed to enable full comprehension of the pathologic mechanisms and the effectiveness of reinforcement techniques during growth. Our aim was to develop a large-animal model of the Ross operation, to reproduce the clinical scenario in which this procedure might be applied, and allow for development and testing of various devices and techniques to improve PA performance. In addition, we aimed to test the effectiveness of a bioresorbable mesh for PA reinforcement.

METHODS

An experimental model of transposition of the pulmonary trunk as an autograft in the aortic position has been developed and performed under cardiopulmonary bypass in 20 growing lambs, aged 3 months. The experimental design included: a control group that underwent PA transposition; a group in which the PA was reinforced with an external, synthetic, nonresorbable, polypropylene grid; and a group that received various combinations of resorbable meshes. Animals were followed up during growth for 6 months by angiography and echocardiography and eventually killed for pathologic analysis.

RESULTS

All animals survived the procedure with no complications. The model was easy and reproducible. Resorbable meshes prevented PA dilation and preserved its progressive growth process, aiding histologic remodelling.

CONCLUSIONS

We developed an easy and reproducible model of the Ross procedure, allowing for a reliable simulation of the clinical scenario. Resorbable PA reinforcement may represent an interesting option in this context.

Aortic valve replacement in children: Options and outcomes

Several disease pathologies such as congenital heart disease and rheumatic fever can affect the aortic valve (AV) in children frequently necessitating intervention. While percutaneous or surgical AV repair is recommended as initial management strategy in children with AV disease, AV replacement (AVR) might become necessary in children with significant valve destruction and after repair or intervention failure. AVR in children is associated with distinct clinical and technical problems owing to several anatomic, social and prosthesis-related issues. In the current review, we list different AV substitutes, discuss their advantages and shortcomings, outline AVR results in children, and explore the divergence of outcomes in various age, anatomy and pathology subgroups; all in the aim to identify optimal AVR choice for each patient taking into consideration his unique anatomic and demographic characteristics.

Patient Age at the Ross Operation in Children Influences Aortic Root Dimensions and Aortic Regurgitation

Background:

The Ross operation provides the advantage of growth potential of the pulmonary autograft in the aortic position. However, development of autograft dilatation and regurgitation may occur. We sought to assess the progression of autograft diameters and aortic regurgitation (AR) with regard to patient age at the time of the Ross operation.

Methods:

Autograft echo dimensions from 48 children <16 years of age at the time of the Ross operation, who had follow-up echocardiograms at <20 years of age, were analyzed using hierarchical multilevel modeling. The z values of autograft dimensions were calculated according to the normal aortic dimensions. Mean follow-up was 5.1 ± 3.3 years. The mean age at the time of the Ross operation was 10.0 ± 4.3 years.

Results:

The mean z values of all patients showed a significant increase with follow-up time at the sinus (0.5 ± 0.1/year, P < .001) and the sinotubular junction (0.7 ± 0.2/year, P < .001) but not at the annulus (0.1 ± 0.1/year, P = .59). There was no significant difference in the z values of sinus and the sinotubular junction between younger and older children at implantation and with time. The initial annulus z value was significantly larger in younger children ( P < .0001), whereas the annual increase was significantly higher in older children ( P = .021). Age at operation has no impact on the initial AR grade ( P = .60). The AR tends to increase more quickly in older patients ( P = .040). Sinus and sinotubular junction dilate with time, regardless of patient age.

Conclusions:

Young children show larger initial annulus sizes than older children. However, annulus diameters tend to normalize in young children, whereas they increase in older children. Autograft regurgitation develops slowly, but significantly, and predominantly in older children. Stabilizing measures to prevent autograft root dilatation are warranted in adolescents, but they are not required in young children.

Similarities and differences of the aortic root after arterial switch and ross operation in children

Pulmonary root dilation and valve regurgitation if translocated into the aortic position is frequently seen in children with transposition of the great arteries (TGA) after an arterial switch operation, as well as in patients after the Ross procedure. Many mechanisms are thought to be responsible for the progressive dilation. Despite the differences between the 2 groups, the similarity of having the pulmonary valve and its adjacent tissue working in the systemic circulation might have a comparable effect on the neoaortic root dimensions and elasticity. We prospectively recruited 52 patients with TGA, 23 Ross patients, and 48 healthy subjects for echocardiographic assessment of their aortic valve, root, sinutubular junction, and ascending aortic dimensions and elasticity. The data were compared, stratified by patient age at investigation and the duration of follow-up postoperatively. In relation to the healthy subjects, the neoaortic root dimensions were significantly larger and the tissue stiffer and less distensible in those with TGA and those who had undergone the Ross procedure. Although the pulmonary valve of the Ross patients had been under systemic pressure load for a significantly shorter period (4.4 ± 3.6 vs 10.1 ± 5.5 years), the dimensions and elasticity values had deteriorated more. These differences could neither be clearly attributed to the age differences at surgery or to an auxiliary congenital ventricular septal defect in those with TGA or the aortic valve phenotype before the Ross operation. In conclusion, the worse outcome of the neoaortic root dimensions and elasticity in the Ross patients should at least be partly related to the different predefined pulmonary artery structures and the different development of the normal and transposed pulmonary arteries.

Aortic valve disease and treatment: the need for naturally engineered solutions

The aortic valve regulates unidirectional flow of oxygenated blood to the myocardium and arterial system. The natural anatomical geometry and microstructural complexity ensures biomechanically and hemodynamically efficient function. The compliant cusps are populated with unique cell phenotypes that continually remodel tissue for long-term durability within an extremely demanding mechanical environment. Alteration from normal valve homeostasis arises from genetic and microenvironmental (mechanical) sources, which lead to congenital and/or premature structural degeneration. Aortic valve stenosis pathobiology shares some features of atherosclerosis, but its final calcification endpoint is distinct. Despite its broad and significant clinical significance, very little is known about the mechanisms of normal valve mechanobiology and mechanisms of disease. This is reflected in the paucity of predictive diagnostic tools, early stage interventional strategies, and stagnation in regenerative medicine innovation. Tissue engineering has unique potential for aortic valve disease therapy, but overcoming current design pitfalls will require even more multidisciplinary effort. This review summarizes the latest advancements in aortic valve research and highlights important future directions.

Major adverse cardiac and cerebrovascular events after the Ross procedure: a report from the German-Dutch Ross Registry

BACKGROUND

The purpose of the study is to report major cardiac and cerebrovascular events after the Ross procedure in the large adult and pediatric population of the German-Dutch Ross registry. These data could provide an additional basis for discussions among physicians and a source of information for patients.

METHODS AND RESULTS

One thousand six hundred twenty patients (1420 adults; 1211 male; mean age, 39.2±16.2 years) underwent a Ross procedure between 1988 and 2008. Follow-up was performed on an annual basis (median, 6.2 years; 10 747 patient-years). Early and late mortality were 1.2% (n=19) and 3.6% (n=58; 0.54%/patient-year), respectively. Ninety-three patients underwent 99 reinterventions on the autograft (0.92%/patient-year); 78 reinterventions in 63 patients on the pulmonary conduit were performed (0.73%/patient-year). Freedom from autograft or pulmonary conduit reoperation was 98.2%, 95.1%, and 89% at 1, 5, and 10 years, respectively. Preoperative aortic regurgitation and the root replacement technique without surgical autograft reinforcement were associated with a greater hazard for autograft reoperation. Major internal or external bleeding occurred in 17 (0.15%/patient-year), and a total of 38 patients had composite end point of thrombosis, embolism, or bleeding (0.35%/patient-year). Late endocarditis with medical (n=16) or surgical treatment (n=29) was observed in 38 patients (0.38%/patient-year). Freedom from any valve-related event was 94.9% at 1 year, 90.7% at 5 years, and 82.5% at 10 years.

CONCLUSIONS

Although longer follow-up of patients who undergo Ross operation is needed, the present series confirms that the autograft procedure is a valid option to treat aortic valve disease in selected patients. The nonreinforced full root technique and preoperative aortic regurgitation are predictors for autograft failure and warrant further consideration. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00708409.

Neoaortic Valve Function 10 to 18 Years After Arterial Switch Operation

Anatomical correction is a procedure of choice for transposition of the great arteries (TGA) in neonates. During surgery, the aorta and pulmonary artery are switched—the native pulmonary valve becomes the neoaortic valve. The fate of this valve remains uncertain. Many reports suggest that its ability to function worsens with time after surgery. Of 519 patients with TGA operated on between 1991 and 2008, 161 met inclusion criteria for this retrospective study and were followed 10 years or more to assess neoaortic valve regurgitation (NeoAR) occurrence and development and to estimate potential risk factors. The subjects were divided into 2 groups: group 1 (simple TGA) and group 2 (TGA + ventricle septal defect). Within the analyzed group, the frequency of significant regurgitation increased from 9% 1 year after the operation to 47% at the most recent follow-up. No severe regurgitation necessitating reoperation was observed. Analysis of potential risk factors revealed that pulmonary/aortic valve diameter discrepancy and nonfacing commissures were associated with increased risk of development of neoaortic insufficiency. NeoAR arises and develops over time after correction of the defect. No hemodynamic repercussions necessitating cardiac surgical interventions were observed. The majority of insufficiencies are detected between 2 and 6 years after surgery. The degree of incompetence is usually mild and increases during follow-up by about 0.5 or 1 degree. The risk factors for NeoAR appearance are pulmonary artery/aortic annulus discrepancy and nonfacing commissures.