Stenting of Native Right Ventricular Outflow Tract Obstructions in Symptomatic Infants.

OBJECTIVE: To assess feasibility, safety and effectiveness of right ventricular outflow tract (RVOT) stenting in symptomatic young infants. METHODS: Multicentre evaluation of 35 patients intended to undergo RVOT stenting in 11 pediatric cardiac centres from 2009 to August 2011. RESULTS: Median age and weight at the time of first stent implantation were 8 weeks and 3.3 kg, with 40% of patients <3 kg. A total of 19 patients had suffered from hypoxemic spells, 8 patients were ventilated, 6 on inotropic support and 5 on prostaglandin infusion. Severe concomitant malformations were present in 11 patients, and acute infections in 2. Stenting of the RVOT was successfully performed in 33 patients, improving oxygen saturation from a median of 77 to 90% 2 days after intervention. Besides the 2 patients in whom RVOT stenting was not successful for technical reasons, there were no procedural complications. In 17 of 33 patients, 1-3 reinterventions were performed during follow-up, less than half of those were reinterventions in the RVOT. A total of 27 patients have undergone successful surgical repair 4-162 (median 19.5) weeks after initial RVOT stent implantation, 2 patients are still waiting. There were no perioperative deaths. CONCLUSIONS: Stenting of the RVOT provides a safe and effective management strategy for initial palliation in symptomatic young infants, including those patients not suitable or at higher risk for surgical therapy.

Echocardiographic evaluation of congenital left ventricular outflow obstruction.

Left ventricular outflow obstructions (LVOTO) encompass a series of stenotic lesions beginning within the anatomic left ventricular outflow tract and ending in the descending thoracic aorta, occurring alone or in series. The degree of stenosis and hemodynamic consequences may vary from mild and well tolerated to severe and functionally limiting. The majority of LVOTO (with the exception of calcific and rheumatic aortic stenosis) are congenital in etiology. Echocardiography has become an integral tool in the assessment of patients with congenital heart disease. This article is a contemporary review of the clinical features of LVOTO and the role of echocardiography in this patient population.

[Discrete Subaortic Stenosis in an Adult; Report of a Case].

Discrete subaortic stenosis (DSS) is a well-described cause of isolated left ventricular outflow tract obstruction( LVOTO) in children. But prevalence, rate of progression and postoperative data in adults are limited. We report a case of a 30-year-old woman, who was referred to our institution because of chest pain and loss of consciousness. Echocardiography revealed DSS with LVOTO (peak gradient 81 mmHg) and mild aortic regurgitation. Increased age at the time of diagnosis, female sex and preoperative left ventricular outflow tract(LVOT) gradient ≥80 mmHg were thought to be predictors for reoperation, therefore the obstructing membrane was circumferentially excised and concomitant localized myectomy of the ventricular septum was performed to achieve complete relief of the LVOT obstruction. Her postoperative course was uneventful, and she was discharged on the 5th postoperative day.

Outcomes of the modified norwood procedure: hypoplastic left heart syndrome versus other single-ventricle malformations.

Recent studies have suggested that survival after the modified Norwood procedure is influenced by anatomy and is worse for patients with hypoplastic left heart syndrome (HLHS) than for patients with other forms of functional single ventricle. This study aimed to compare the outcomes of the modified Norwood procedure for these two groups at a single center. A retrospective chart review compared modified Norwood procedure outcomes between children with HLHS (n = 40) and children with other single-ventricle malformations (n = 19) from January 2002 to August 2012. The HLHS patients had a lower mean age (10.0 ± 13.2 days) at the time of operation than the non-HLHS patients (16.5 ± 18.5 days). The difference was not significant. The number of patients with a Sano modification was significantly higher in the HLHS group (HLHS 85 % vs non-HLHS 32 %; p < 0.001). The follow-up data did not differ between the groups (HLHS 3.6 ± 3.2 years vs non-HLHS 4.8 ± 3.3 years, nonsignificant difference). The overall operative survival was 85 %: 83 % for the patients with HLHS and 89 % for the patients with non-HLHS (nonsignificant difference). The Kaplan-Meier transplant-free survival estimate at 10 years was 73 % and did not differ between the HLHS patients (67 %) and the non-HLHS patients (84 %, nonsignificant difference). The timing of stages 2 and 3 palliation (bidirectional Glenn and external conduit Fontan) did not differ significantly (HLHS, 7.0 ± 2.8 months and 3.0 ± 0.5 years vs non-HLHS 6.1 ± 1.7 months and 2.8 ± 0.8 years). The two groups were similar with respect to the need for post-Norwood extracorporeal membrane oxygenation support, aortic arch reinterventions, atrioventricular valve repair, pulmonary artery reconstruction, pacemaker implantation, and progression to bidirectional Glenn and Fontan completion. The modified Norwood reconstruction provides good palliation for HLHS as well as other forms of functional single-ventricle anatomy. Survival, postoperative morbidity, and progression to Glenn and Fontan are not significantly different.

Risk factors in the origin of congenital left-ventricular outflow-tract obstruction defects of the heart: a population-based case-control study.

The aim of our project was to study possible etiological factors in the origin of congenital heart defects (CHDs) because in the majority of patients the underlying causes are unclear. Cases with different CHD entities as homogeneously as possible were planned for evaluation in the population-based large data set of the Hungarian Case Control Surveillance of Congenital Abnormalities. Dead or surgically corrected 302 live-born cases with different types of left-ventricular outflow tract obstructive defects (LVOT, i.e., valvular aortic stenosis 76, hypoplastic left heart syndrome 76, coarctation of the aorta 113, and other congenital anomalies of aorta 32) were compared with 469 matched controls, 38,151 controls without any defects, and 20,750 malformed controls with other isolated defects. Medically recorded pregnancy complications and chronic diseases were evaluated based on prenatal maternity logbooks, whereas acute diseases, drug treatments, and folic acid/multivitamin supplementation were analyzed both on the basis of retrospective maternal information and medical records. The results of the study showed the role of maternal diabetes in the origin of LVOT in general, while panic disorder was associated with a higher risk of hypoplastic left heart syndrome and ampicillin treatment with a higher risk of coarctation of the aorta (COA). High doses of folic acid had a protective effect regarding the manifestation of LVOT, particularly COA. In conclusion, only a minor portion of causes was shown in our study; thus, further studies are needed to understand better the underlying causal factors in the origin of LVOT.

The Ross, Konno, and Ross-Konno operations for congenital left ventricular outflow tract abnormalities.

Operations for left ventricular outflow tract abnormalities are centred on hemodynamic conditions that relate to subvalvar stenosis, valvar stenosis/regurgitation, aortic annular hypoplasia, and supravalvar aortic stenosis. Operative interventions over the years have evolved because the intervening outcomes proved to be unsatisfactory. The resection for subvalvar aortic stenosis has progressed from a fibrous "membrane" resection to a more extensive fibromuscular resection. Operative solutions for valvar aortic stenosis and regurgitation have resulted in operative interventions that depend on simple commissurotomy, leaflet extensions, prosthetic mechanical valve replacement, biologic valve replacement, including the pulmonary autograft, and operations to treat aortic annular stenosis. Although there are enthusiastic proponents for all of these strategies, the fact remains that none have proven to be curative; patients can expect to undergo further procedures during their lifetimes. The short- and mid-term solutions to these left ventricular outflow tract abnormalities have improved based on operations that have been attended by increasing operative complexity. The purpose of this review is to chronicle the operative steps of the Ross operation, the Konno-Rastan operation, the modified Konno operation, the Ross-Konno operation, and the modified Ross-Konno operation.

Porcine bioprosthetic valve in the pulmonary position: mid-term results in the right ventricular outflow tract reconstruction.

Pulmonary valve replacement (PVR) for pulmonary valve insufficiency (PVI) currently represents the most frequent reoperation performed for adults with congenital heart disease. A variety of pulmonary valve substitutes have been used, but none has proved to be ideal. This report reviews the authors' experience using a porcine prosthetic valve in the pulmonary position. Between January 2001 and December 2011, 76 patients (mean age, 36 years; range, 18-64 years) underwent PVR for chronic PVI using a porcine bioprosthesis. All the patients had previously undergone surgery: 65 for repair of tetralogy of Fallot and 11 for pulmonary surgical valvotomy. Magnetic resonance imaging (MRI) evaluations before surgery and at the 1-year postoperative follow-up evaluation were compared. Aside from the PVR, 59 patients (59/65, 78 %) received 94 associated cardiac surgical procedures. Two hospital deaths occurred. The mean hospital stay was 13 days (range, 7-48 days). At the 1-year control MRI, pulmonary regurgitation fraction, right ventricular end diastolic volume (RVEDV), and RV/LV EDV had improved significantly. During a mean follow-up period of 52 months (range, 6-132 months), one patient died. All the patients were categorized as New York heart association (NYHA) functional class 1. No episodes of structural valve deterioration, endocarditis, or thromboembolic event were noted. Echocardiography showed trivial or no PVI in all the patients. The porcine bioprosthetic valves demonstrated excellent midterm results in the RV outflow tract reconstruction. The hemodynamic characteristics of this valve are comparable with those of homografts or valved conduits. It is easy to implant and allows for avoiding extensive dissection, especially of the pulmonary arteries.

Aortico-left ventricular tunnel: the elusive diagnosis.

We present a case of an infant prenatally diagnosed with bilateral outflow-tract obstruction and severe aortic regurgitation who underwent cardiac transplantation at 45 days of life. Aortico-left ventricular tunnel was subsequently diagnosed on pathologic examination of the explant heart. Aortico-left ventricular tunnel is a rare congenital cardiac malformation and can remain undiagnosed if the clinician has a low level of suspicion. Aortico-left ventricular tunnel should be considered in any fetus or newborn with aortic regurgitation.

Computed Tomographic Evaluation of Congenital Left Ventricular Outflow Obstruction.

Congenital left ventricular outflow obstruction represents a multilevel obstruction with several morphological forms. It can involve the subvalvular, valvar, or supravalvular portion of the aortic valve complex, and may coexist. Computed tomography (CT) plays an important supplementary role in the evaluation of patients with congenital LVOT obstruction. Unlike transthoracic echocardiography and cardiovascular magnetic resonance (CMR) imaging, it is not bounded by a small acoustic window, needs for anaesthesia or sedation, and metallic devices. Current generations of CT scanners with excellent spatial and temporal resolution, high pitch scanning, wide detector system, dose reduction algorithms, and advanced 3-dimensional postprocessing techniques provide a high-quality alternative to CMR or diagnostic cardiac catheterization. Radiologists performing CT in young children should be familiar with the advantages and disadvantages of CT and with the typical morphological imaging features of congenital left ventricular outflow obstruction.

The Ross-Konno procedure as reoperative treatment in a young adult with congenital aortic stenosis.

Mechanical and biological prostheses are valid options when aortic valve replacement is necessary. The Ross procedure is also an alternative solution, especially for young patients. We describe the case of a young patient with congenital aortic stenosis and bicuspid aortic valve who presented with dyspnea on exertion. An open commissurotomy was performed, and within 8 months the patient developed recurrent symptoms of severe aortic stenosis. He underwent redo sternotomy and a Ross-Konno procedure with an uneventful recovery.

Association of common variants in ERBB4 with congenital left ventricular outflow tract obstruction defects.

BACKGROUND: The left ventricular outflow tract (LVOT) defects aortic valve stenosis (AVS), coarctation of the aorta (COA), and hypoplastic left heart syndrome (HLHS) represent an embryologically related group of congenital cardiovascular malformations. They are common and cause substantial morbidity and mortality. Prior evidence suggests a strong genetic component in their causation. METHODS: We selected NRG1, ERBB3, and ERBB4 of the epidermal growth factor receptor (EGFR) signaling pathway as candidate genes for investigation of association with LVOT defects based on the importance of this pathway in cardiac development and the phenotypes in knockout mouse models. Single nucleotide polymorphism (SNP) genotyping was performed on 343 affected case-parent trios of European ancestry. RESULTS: We identified a specific haplotype in intron 3 of ERBB4 that was positively associated with the combined LVOT defects phenotype (p=0.0005) and in each anatomic defect AVS, COA, and HLHS separately. Mutation screening of individuals with an LVOT defect failed to identify a coding sequence or splice site change in ERBB4. RT-PCR on lymphoblastoid cells from LVOT subjects did not show altered splice variant ratios among those homozygous for the associated haplotype. CONCLUSION: These results suggest ERBB4 is associated with LVOT defects. Further replication will be required in separate cohorts to confirm the consistency of the observed association.

Double chambered right ventricle with ventricular septal defect presenting in adulthood.

Double-chambered right ventricle (DCRV) is a form of right ventricular outflow tract obstruction. It typically presents in childhood or adolescence. Only a handful of previous cases have been described in which DCRV occurred in adulthood. We report here a case of DCRV with ventricular septal defect (VSD) presenting in adulthood.

NOTCH1 mutations in individuals with left ventricular outflow tract malformations reduce ligand-induced signaling.

Congenital aortic valve stenosis (AVS), coarctation of the aorta (COA) and hypoplastic left heart syndrome (HLHS) are congenital cardiovascular malformations that all involve the left ventricular outflow tract (LVOT). They are presumably caused by a similar developmental mechanism involving the developing endothelium. The exact etiology for most LVOT malformations is unknown, but a strong genetic component has been established. We demonstrate here that mutations in the gene NOTCH1, coding for a receptor in a developmentally important signaling pathway, are found across the spectrum of LVOT defects. We identify two specific mutations that reduce ligand (JAGGED1) induced NOTCH1 signaling. One of these mutations perturbs the S1 cleavage of the receptor in the Golgi. These findings suggest that the levels of NOTCH1 signaling are tightly regulated during cardiovascular development, and that relatively minor alterations may promote LVOT defects. These results also establish for the first time that AVS, COA and HLHS can share a common pathogenetic mechanism at the molecular level, explaining observations of these defects co-occurring within families.

Mutations in VEGFA are associated with congenital left ventricular outflow tract obstruction.

Left ventricular outflow tract obstruction (LVOTO) comprises a spectrum of stenotic lesions. Previous studies have shown that the vascular endothelial growth factor (VEGF) signaling system plays a critical role in cardiac cushion formation, vasculogenesis, and angiogenesis. We hypothesize that VEGFA may be a potential candidate gene associated with the spectrum of LVOTO lesions. However, it remains unclear whether the VEGFA gene is responsible for the development of LVOTO malformations. In this study, we identified three exon mutations in the VEGFA gene in three of 192 nonsyndromic LVOTO patients, and the overall mutation frequency was 1.6% (3/192). The c.454C>T (p.Arg152X) nonsense mutation and c.19_22dupGACA (p.Thr8ArgfsX78) internal tandem duplication mutation each introduced a premature stop codon and are predicted to produce a truncated VEGFA protein. The c.998G>A missense mutation changes a highly conserved arginine to a glutamine at residue 333 (p.Arg333Gln). These mutations were carried by some family members, and average penetrance was 33.3%. The present study suggests, for the first time to our knowledge, that VEGFA mutations may be associated with congenital LVOTO malformations. We provide evidence that LVOTO is likely oligogenic.

Left outflow tract anomalies in children.

PURPOSE OF REVIEW: To provide a discussion of the current knowledge of the genetics of left outflow tract of the heart, including the aortic stenosis, in children. It addresses the available means of diagnosis for syndromic and nonsyndromic left outflow tract abnormalities and implications for at-risk family members. Options for prenatal testing and recommendations for cardiac follow-up are presented. RECENT FINDINGS: Left outflow tract cardiac anomalies in children present as a varied spectrum among and within families. Even nonsyndromic forms can be inherited in an autosomal dominant pattern. These can lead to significant complications in asymptomatic individuals, making diagnosis a challenge and underscoring the importance of evaluation of at-risk family members. SUMMARY: Improved understanding of the genetics of both syndromic and nonsyndromic left outflow tract disorders is hoped to lead to improved identification of affected children and greater ongoing cardiac follow-up for those potentially at risk.

Delayed improvement of right ventricular diastolic function and regression of right ventricular mass after percutaneous pulmonary valve implantation in patients with congenital heart disease.

BACKGROUND: Percutaneous pulmonary valve implantation (PPVI) has been introduced as therapy for right ventricular (RV) to pulmonary artery conduit dysfunction in patients with congenital heart disease. It has been shown that RV systolic function improved early after PPVI. The effects of PPVI on RV diastolic function and RV hypertrophy have not yet been studied. PURPOSE: The objective of this study is to assess early and late changes in systolic and diastolic RV function and RV mass after PPVI. MATERIALS AND METHODS: Fourteen patients underwent PPVI (7 male, median age 15 years). Cardiac magnetic resonance imaging was performed before and at 2 time points after PPVI (at 1 and 16 months). Right ventricular volume and systolic and diastolic function as well as RV mass were assessed. RESULTS: At 1 and 16 months after PPVI, the RV mass decreased from 28.6 +/- 2.1 to 25.6 +/- 2.2 g/m(2) (P = .03) and to 22.3 +/- 2.1 g/m(2) (P = .002). E/A volume ratio increased from 1.91 +/- 0.4 to 2.6 +/- 0.4 (not significant [NS]) and to 3.3 +/- 0.4 (P = .01). E/A peak flow ratio increased from 1.34 +/- 0.14 to 1.48 +/- 0.16 (NS) and to 1.73 +/- 0.14 (P = .04). E-wave deceleration time increased from 142 +/- 25 to 160 +/- 27 milliseconds (NS) and to 211 +/- 26 milliseconds (P = .007). At 1 month, RV end-diastolic volume decreased from 124 +/- 8 to 113 +/- 8 mL (P = .01) and RV ejection fraction increased from 36% +/- 2% to 46% +/- 2% (P = .001) without further improvement at 16 months. CONCLUSION: After PPVI, in contrast to rapid improvement of RV systolic function, the improvement of RV diastolic function is delayed. The reduction of RV mass appears to be the underlying mechanism for improvement of RV diastolic function. Long follow-up for patients with PPVI is recommended.

Cardiac malformation in neonatal mice lacking connexin43.

Gap junctions are made up of connexin proteins, which comprise a multigene family in mammals. Targeted mutagenesis of connexin43 (Cx43), one of the most prevalent connexin proteins, showed that its absence was compatible with survival of mouse embryos to term, even though mutant cell lines showed reduced dye coupling in vitro. However, mutant embryos died at birth, as a result of a failure in pulmonary gas exchange caused by a swelling and blockage of the right ventricular outflow tract from the heart. This finding suggests that Cx43 plays an essential role in heart development but that there is functional compensation among connexins in other parts of the developing fetus.

Ross and Ross-Konno procedures in infants, children and adolescents: a 13-year experience.

BACKGROUND AND AIM OF THE STUDY: Due to hemodynamic performance and potential for growth of the pulmonary autograft, the Ross operation is considered to be the surgery of choice for irreparable aortic valve disease in pediatric patients. The study aim was to analyze the long-term clinical and echocardiographic results of the Ross operation. METHODS: Between February 1993 and July 2006, 55 consecutive patients (mean age 10.0 +/- 6.2 years; range: 3 months to 18 years) underwent eithera Ross operation (n=46) or a Ross-Konno procedure (n=9). The underlying left ventricular outflow tract pathology was mainly congenital (n=47). Among patients, 23 (42%) had undergone a previous aortic valve procedure. Concomitant procedures were performed in 16 patients (29%). The Ross operation was performed as a root replacement in all cases; the mean cross-clamp time was 132 min (range: 100-188 min). The autograft diameter was indexed to the body surface area and compared to normal values. The mean follow up was 5.5 +/- 3.8 years, and was 100% complete. RESULTS: There was one early death (2%) and two late deaths (4%). The actuarial patient survival was 93% at 10 years. None of the patients developed moderate or severe autograft regurgitation. All measured maximal root diameters were above the 90th percentile of normal aortic diameter, without correlation to autograft regurgitation. Five patients (9%) had a mean homograft gradient > or = 40 mmHg, and two (4%) were reoperated on. The freedom from reoperation for homograft degeneration was 91% at 10 years. CONCLUSION: Autograft regurgitation after the Ross and Ross-Konno procedures is uncommon, and the risk of homograft degeneration appears low. Autograft dilatation is common but does not correlate with autograft regurgitation. When considering long-term freedom from autograft and homograft degeneration, the results of the present study confirm the Ross operation as the surgery of choice for irreparable aortic valve disease in infants, children and young adults.

Implantation of drug-eluting stents for relief of obstructed infra-cardiac totally anomalous pulmonary venous connection in isomerism of the right atrial appendages.

We describe an infant with severe obstruction of infra-cardiac totally anomalous pulmonary venous connection associated with right isomerism, atrioventricular septal defect, pulmonary atresia, and multiple aortopulmonary collateral arteries. Implantation of a stent into the obstructed descending vertical vein provided effective palliation, with a dramatic increase in saturations of oxygen obviating the need for urgent high-risk surgery.

Right ventricular outflow tract obstruction: a quest for ideal management.

Management of right ventricular outflow tract obstruction has undergone much change over the last century. Techniques described in the literature include anatomical repairs and the use of various patches, conduits, and innovative grafts. However, many of these approaches require reoperations or catheter-based interventions, leading to increased morbidity, mortality, and cost. The search for the ideal long-lasting conduit continues and there are new techniques on the horizon, using genetic engineering and nanotechnology. This review discusses the evolution of various techniques for repair of right ventricular outflow tract obstruction, past and current conduits, as well as ongoing research.