Predicting late sudden death from ventricular arrhythmia in adults following surgical repair of tetralogy of Fallot

Strengths, Limitations, and Geographical Discrepancies in the Eligibility Criteria for Sport Participation in Young Patients With Congenital Heart Disease

OBJECTIVE

Benefits of physical activity has been shown in children with congenital heart disease (CHD). In several forms of CHD, the risk of sudden death remains a major concern both for parents and clinicians, who in turn will have to consider the risk-benefit ratio of sport participation versus restriction.

DATA SOURCE

A literature search was performed within the National Library of Medicine using the keywords: Sport, CHD, and Eligibility. The search was further refined by adding the keywords: Children, Adult, and Criteria.

MAIN RESULTS

Fifteen published studies evaluating sport eligibility criteria in CHD were included. Seven documents from various scientific societies have been published in the past decade but which of them should be adopted remains unclear. Our research highlighted accuracy and consistency of the latest documents; however, differences have emerged between the US and European recommendations. Eligibility criteria were consistent between countries for simple congenital heart defects, whereas there are discrepancies for borderline conditions including moderate valvular lesions and mild or moderate residual defects after CHD repair. Furthermore, some of the more severe defects were not evaluated. Multiple recommendations have been made for the same CHD, and cut-off values used to define disease severity have varied. Published eligibility criteria have mainly focused on competitive sports. Little attention was paid to recreational activities, and the psychosocial consequences of activity restriction were seldom evaluated.

CONCLUSIONS

Comprehensive consensus recommendations for sport eligibility evaluating all CHD types and stages of repair are needed. These should include competitive and recreational activities, use standardized classifications to grade disease severity, and address the consequences of restriction.

Predictors of ventricular tachyarrhythmia occurring late after intracardiac repair of tetralogy of Fallot: combination of QRS duration change rate and tricuspid regurgitation pressure gradient

Background

To determine potential predictors of ventricular tachyarrhythmia and sudden cardiac death (SCD) occurring late after repair of tetralogy of Fallot (TOF).

Methods

Since 1964, 415 patients had undergone total repair for TOF at Niigata University Hospital. Of these, 89 patients who were followed for more than 10 years at our institute were retrospectively reviewed.

Results

The mean follow-up period was 24.3 years. During the study period, one patient died of cerebral bleeding, and two patients had SCD. The overall survival rates at 20, 30, and 40 years were 100%, 94.6%, and 94.6%, respectively. Eight (9.0%) patients required re-intervention during the late period associated with right ventricular outflow (n=4), tricuspid valve (n=3), aortic valve (n=2), and others (n=2). Ten (11.2%) patients had a history of ventricular tachycardia (VT) or ventricular fibrillation (VF), and six underwent implantation of an implantable cardiac defibrillator. Multivariate analysis selected the change rate of QRS duration [ms/year; odds ratio (OR), 2.44; 95% confidence interval (CI): 1.28-4.65; P=0.007] and the pressure gradient at tricuspid valve regurgitation on echocardiography (OR, 1.12; 95% CI: 1.02-1.22; P=0.017) as risk factors for VT/VF or SCD. Trans-annular patch (TAP) repair was not an independent risk factor for ventricular arrhythmia.

Conclusions

The combination of rapid change rate of QRS duration and higher-pressure gradient at tricuspid regurgitation were risk factors for ventricular tachyarrhythmia late after TOF repair. Adequate surgical or catheter intervention for pressure and volume load in the right ventricle might decrease the prevalence of VT/VF and SCD.

Comparison of the Degree of Exercise Tolerance in Children After Surgical Treatment of Complex Cardiac Defects, Assessed Using Ergospirometry and the Level of Brain Natriuretic Peptide

Children who underwent surgery for complex congenital heart defects present worse exercise capacity than their healthy peers. In adults and adolescents, heart failure is assessed on the basis of clinical symptoms using the New York Heart Association (NYHA) score, while in an infant Ross scale; heart failure can also be evaluated by other parameters. The purpose of this study was to compare the degree of exercise tolerance in children after surgery for complex heart defects, assessed by the ratio of maximum oxygen uptake (VO2max) and the brain natriuretic peptide (N-terminal fragment of the prohormone brain-type natriuretic peptide [NT-proBNP]) concentration.The study group consisted of 42 children, ages 9 to 17 years (mean 14.00 ± 2.72). Among them there were 22 children with tetralogy of Fallot (ToF) after total correction, 18 children with transposition of the great arteries (d-TGA) after the arterial switch operation, and 2 children with single ventricle (SV) after the Fontan operation. All but 1 child were in NYHA class I. The control group consisted of 20 healthy children. Outcomes of interest were the ratio of VO2max, determined during ergospirometry, and the level of NT-proBNP. The statistical analysis was performed and the groups were considered significantly different for P < 0.05.There was no statistically significant correlation between NT-proBNP and maximum oxygen uptake (VO2) kg min in the study group compared with the control group.The VO2max in the test group had a mean value less (34.6 ± 8.0) than controls (38.4 ± 7.7), and the differences were statistically significant (P = 0.041). In contrast, the average concentration of NT-proBNP in the study group was higher than controls (117.9 ± 74.3 vs 18.0 ± 24.5), and these differences were statistically significant (P < 0.001).After operations for complex heart defects (ToF, TGA, and SV), children have worse heart function parameters and exercise capacity than the healthy population. To control this, we recommend postoperative ergospirometry and determination of NT-proBNP concentrations.

Heterogeneity of Ventricular Sympathetic Nervous Activity is Associated with Clinically Relevant Ventricular Arrhythmia in Postoperative Patients with Tetralogy of Fallot

This study aimed to clarify whether there is an association between ventricular sympathetic nervous activity (SNA) and clinically relevant ventricular arrhythmia (a run of ≥ 3 consecutive ventricular beats, RVA) in postoperative patients with tetralogy of Fallot (TOF). We performed a retrospective study in a national referral center of pediatric cardiology in Japan. Twenty-four postoperative TOF patients (13 males, median age 17 years) undergoing myocardial (123)I metaiodobenzylguanidine (MIBG) scintigraphy were included. We measured the heart-to-mediastinum ratio (HMR) and washout ratio (WR) from planar MIBG myocardial scintigraphy. Tomographic images and polar maps were generated with 20 segments. The standard deviation of percentage uptake of 20 segments (SD-uptake) as an index of heterogeneous MIBG uptake to the ventricular myocardium was calculated. We compared these MIBG-derived variables with the patients' clinical profiles, including ECG findings and hemodynamics. Eight of 24 patients had RVA (RVA group), and the other 16 did not have RVA (non-RVA group). There were no significant differences in the HMR (1.9 ± 0.5 vs. 2.2 ± 0.4) and WR (50 ± 5 vs. 42 ± 10) between the two groups. SD-uptake was significantly higher in the RVA group than in the non-RVA group (15 ± 3 vs. 12 ± 3, p = 0.03). QT dispersion (ms) was also higher in the RVA group than in the non-RVA group (53 ± 23 vs. 44 ± 18, p = 0.04). Multivariate logistic regression showed that SD-uptake and QT dispersion were independent predictors in the RVA group (p = 0.02, p = 0.03). In addition to greater QT dispersion, heterogeneous SNA is associated with RVA in TOF patients postoperatively.

Stem Cells and Progenitor Cells for Tissue-Engineered Solutions to Congenital Heart Defects

Synthetic patches and fixed grafts currently used in the repair of congenital heart defects are nonliving, noncontractile, and not electrically responsive, leading to increased risk of complication, reoperation, and sudden cardiac death. Studies suggest that tissue-engineered patches made from living, functional cells could grow with the patient, facilitate healing, and help recover cardiac function. In this paper, we review the research into possible sources of cardiomyocytes and other cardiac cells, including embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells, adipose-derived stem cells, umbilical cord blood cells, amniotic fluid-derived stem cells, and cardiac progenitor cells. Each cell source has advantages, but also has technical hurdles to overcome, including heterogeneity, functional maturity, immunogenicity, and pathogenicity. Additionally, biomaterials used as patch materials will need to attract and support desired cells and induce minimal immune responses.

Amniotic fluid-derived stem cells demonstrated cardiogenic potential in indirect co-culture with human cardiac cells

Amniotic fluid-derived stem cells (AFSC) have been shown to be broadly multipotent and non-tumorogenic. Previous studies of direct mixing of AFSC and neonatal rat ventricle myocytes indicated evidence of AFSC cardiogenesis. In this study, we examined human AFSC cardiogenic potential in indirect co-culture with human cardiac cells in conditions that eliminated the possibility of cell fusion. Human AFSC in contact with human cardiac cells showed expression of cardiac troponin T (cTnT) in immunohistochemistry, and no evidence of cell fusion was found through fluorescent in situ hybridization. When indirectly co-cultured with cardiac cells, human AFSC in contact with cardiac cells across a thin porous membrane showed a statistically significant increase in cTnT expression compared to non-contact conditions but lacked upregulation of calcium modulating proteins and did not have functional or morphological characteristics of mature cardiomyocytes. This suggests that contact is a necessary but not sufficient condition for AFSC cardiac differentiation in co-culture with cardiac cells.

Identification of differently expressed genes and small molecule drugs for Tetralogy of Fallot by bioinformatics strategy

This study aimed to screen out differentially expressed genes (DEGs) and explore small molecule drugs for Tetralogy of Fallot (TOF). The gene expression profile of TOF GSE26125 was downloaded from the Gene Expression Omnibus database, including 16 idiopathic TOF samples and five healthy controls. The DEGs were identified by the Limma package in R language and underwent functional enrichment analysis via Database for Annotation, Visualization and Integrated Discovery tools. A protein-protein interaction (PPI) network of DEGs was then constructed and the significant clusters were selected for functional analysis. In addition, the DEGs were mapped to the connectivity map (CMap) database to identify potential small-molecule drugs. As a result, a total of 499 DEGs were selected between TOF and healthy controls. Meanwhile, the functional changes of DEGs related to TOF were mainly associated with cellular respiration and energy metabolism. Furthermore, in the PPI network, two clusters were identified via cluster 1 analysis. And only cluster 1 was significantly enriched into gene ontology terms, including respiratory chain, electron transport chain, and oxidation reduction. The hub gene of cluster 1 was NDUFAB1. Additionally, small molecules, such as harmine, solanine, and testosterone, may have the potential to repair the disordered metabolic pathways of TOF.

Low incidence of arrhythmias in the right ventricular infundibulum sparing approach to tetralogy of Fallot repair

To improve outcomes, including arrhythmia incidence, for patients with tetralogy of Fallot (TOF), the authors' institution adopted an approach that minimizes or avoids transmural incision of the right ventricular outflow tract. When pulmonary blood flow is insufficient during the neonatal period, placement of an aortopulmonary artery shunt is preferred, followed by complete repair later in infancy. This study reviewed the perioperative and mid-term arrhythmia outcomes at the authors' institution using this approach. Patients who underwent TOF repair from 1995 to 2008 were included in the study. Patient demographics and surgical history were collected. The primary end points of the study included documented perioperative arrhythmias and arrhythmias at the 10-year follow-up assessment. Of the 298 patients who underwent TOF repair, 50 (17 %) had undergone prior placement of a systemic-to-pulmonary artery shunt. The median age at repair was 9.7 months (interquartile range, 6.3-16.2 months). Clinically significant perioperative arrhythmias were found in 12 patients (4 %) including 6 junctional tachycardias, 4 atrial tachycardias, and 1 temporary complete heart block. No patients were receiving antiarrhythmic medications more than 24 months after surgery. Of the 298 patients, 86 (29 %) had a follow-up period of 10 years or longer (median, 12.2 years). No patients experienced new arrhythmias, received antiarrhythmic therapy, experienced post-discharge ventricular tachycardia, had atrioventricular block, or required a pacemaker or defibrillator. The right ventricular infundibulum sparing approach is associated with an extremely low incidence of perioperative and midterm arrhythmias. The perioperative and mid-term outcomes compare favorably with existing data from programs favoring neonatal repair. Long-term follow-up evaluation is essential to determine whether this strategy can effectively alter late pathophysiology and minimize late-term arrhythmias and associated mortality.

Early changes in myocardial repolarization and coronary perfusion after cardiopulmonary bypass surgery for ASD repair in children

Background

In adults, impaired myocardial repolarization and increased risk of arrhythmia are known consequences of open heart surgery. Little is known, however, about post-operative consequences of cardiopulmonary bypass surgery in children. The aim of this study was to assess ventricular repolarization and coronary perfusion after bypass surgery for atrial septal defect (ASD) repair in children.

Methods

Twelve patients with ASD were assessed one day before and 5–6 days after ASD repair. Myocardial repolarization (corrected QT interval, QTc, QT dispersion, QTd, and PQ interval) was determined on 12-lead electrocardiograms. Coronary flow in proximal left anterior descending artery (peak flow velocity in diastole, PFVd) was assessed by transthoracic Doppler echocardiography.

Results

Ten of the 12 (83%) children had normal myocardial repolarization before and after surgery. After surgery, QTc increased 1-9% in 5 (42%) patients, decreased 2-11% in 5 (42%) patients and did not change in 2 (16%) patients. Post-op QTc positively correlated with bypass time (R=0.686, p=0.014) and changes in PFVd (R=0.741, p=0.006). After surgery, QTd increased 33-67% in 4 (33%) patients, decreased 25-50% in 6 patients (50%) and did not change in 2 (16%) patients. After surgery, PQ interval increased 5-30% in 4 (33%) patients, decreased 4-29% in 6 (50%) patients and did not change in 1 (8%) patient. Post-op PQ positively correlated with bypass time (R=0.636, p=0.027). As previously reported, PFVd significantly increased after surgery (p<0.001).

Conclusions

Changes in QTc, PQ and PFVd are common in young children undergoing surgery for ASD repair. Post-op QTc significantly correlates with bypass time, suggesting prolonged cardiopulmonary bypass may impair ventricular repolarization. Post-op QTc significantly correlates with PFVd changes, suggesting increased coronary flow may also impair ventricular repolarization. The clinical significance and reversibility of these alternations require further investigations.

Managing the right ventricular outflow tract for pulmonary regurgitation after tetralogy of Fallot repair

The long-term outcome of patients with tetralogy of Fallot (TOF) with reconstruction of the right ventricular (RV) outflow tract is often complicated by the sequelae of severe pulmonary regurgitation. Progressive enlargement of the right ventricle, biventricular dysfunction and arrhythmia are apparent in more than 50% of the patients in the fourth decade of life. Pathophysiologic implications, clinical assessment and diagnostic modalities are discussed, whereas CMR imaging seems to be the procedure of choice. Therapeutical options for rereconstruction of the RV outflow tract are mentioned, surgical and interventional procedures are explained in detail. The optimal timing of reoperation for significant pulmonary regurgitation after TOF repair is still a matter of controversy given the limited runtime of the lately implanted prostheses and the risk of further reoperation. Early surgery is recommended in these patients before symptoms develop, or RV function has declined. Today we believe that waiting for the patient to become symptomatic is too late. All in all, pulmonary valve replacement is at least indicated in patients developing symptoms due to severe pulmonary regurgitation, particularly if associated with substantial or progressive RV dilatation, tricuspid regurgitation and/or supraventricular or ventricular arrhythmias.

QRS Complex Enlargement as a Predictor of Ventricular Arrhythmias in Patients Affected by Surgically Treated Tetralogy of Fallot: A Comprehensive Literature Review and Historical Overview

Tetralogy of Fallot (TOF) is a congenital heart disease frequently treated by surgical repair to relieve symptoms and improve survival. However, despite the performing of an optimal surgical repair, TOF patients are at times characterized by a poor long-term survival rate, likely due to cardiac causes such as ventricular arrhythmias, with subsequent sudden death. In the 80s it was irrefutably demonstrated that QRS prolongation ≥180 msec at basal electrocardiogram is a strong predictor for refining risk stratification for ventricular tachycardia in these patients. The aim of this research was to undertake a review of all studies conducted to assess the impact of QRS duration on the development of life-threatening ventricular arrhythmias in repaired TOF subjects.

Surgical correction of tetralogy of Fallot in a seventy-five year old patient

Tetralogy of Fallot is a congenital heart disease which is mostly diagnosed and treated in infancy. In the literature there are some cases where the diagnosis was made in adults. This report describes the case of a seventy-five year old man who presents with a dilated and severely hypertrophic right ventricle, a ventricular septum defect, an overriding aorta and a severe infundibular stenosis in the right ventricular outflow tract. The diagnosis of an unrepaired Tetralogy of Fallot was made. A full surgical correction of the Tetralogy was performed and the patient received an implantable defibrillator, making him the oldest patient repaired for Tetralogy of Fallot.

Transitional medicine: will emergency medicine physicians be ready for the growing population of adults with congenital heart disease?

BACKGROUND

Currently, approximately 85% of children with significant congenital heart problems survive to adolescence and adulthood. This survival rate represents a dramatic improvement in the medical and surgical care of congenital heart disease (CHD) during the last 35 years. Nevertheless, these patients remain at increased risk for significant cardiac problems long after primary interventions are completed. They are more likely than the general population to seek urgent medical care, often in an emergency department setting. They represent a new and growing population of emergency department patients with a specialized set of problems not traditionally part of the training for emergency medicine (EM) physicians.

OBJECTIVE

We investigated the current scope and status of training for EM physicians in the immediate management of CHD patients as they grow to adolescence and adulthood.

METHODS

We conducted 2 cross-sectional surveys to assess the current training environment for 2 specific groups: (1) US general EM (GEM) residency programs, and (2) US and Canadian pediatric EM (PEM) fellowship programs. Surveys were mailed to program directors during the summer of 2005. A total of 198 surveys were sent out: 134 to GEM residency directors and 64 to PEM fellowship directors.

RESULTS

The response rate overall was 68%, with a 64% response rate from the GEM residency directors and 77% from the PEM fellowship directors. Across all programs, 43% (56/130 respondents) were "unsure" about the existence or location of an adult CHD (ACHD) clinic in their area. When asked to rate the importance of ACHD as a training topic, 40 (85%) of 47 PEM fellowship directors and 62 (74%) of 84 GEM residency directors ranked it as "low priority" or "unnecessary." However, 70 (55%) of 127 respondents were "unsure," "uncomfortable," or "worried" about the ACHD training their trainees receive (PEM, 59%; GEM, 53%). In addition, most program directors (75%) estimated that their trainees care for 5 or fewer ACHD patients annually.

CONCLUSIONS

There seems to be a mismatch between the growing need for ACHD emergency care and the current state of this topic in both GEM residency and PEM fellowship training programs.

Sleep disordered breathing in pediatric patients with tetralogy of Fallot

Adverse effects on the pulmonary circulation in obstructive sleep disordered breathing (SDB) may place children with heart lesions affecting the right ventricle at increased risk for morbidity and mortality. We examined the distribution and effects of SDB in pediatric patients with tetralogy of Fallot (TOF). Families of 37 pediatric patients with TOF completed a survey of cardiac symptoms and school performance as well as a Pediatric Sleep Questionnaire (PSQ), a validated questionnaire for the screening of SDB in children 2-18 years of age. Medical records were reviewed for growth parameters, medical history, and most recent electrocardiogram (ECG) findings. Data from patients with SDB (PSQ score > or = 8, n = 14) were compared to data from patients without SDB (PSQ score < 8; n = 23). The prevalence of SDB in this population (38%) was significantly higher than the published prevalence of 5% in a healthy general pediatric population (p < 0.001). No significant difference was found in age, gender, or age and sex standardized body mass index between patients with or without SDB. No difference was seen in medication use or timing of surgical repair, whether primary or palliative. Patients with SDB had a significantly higher cardiac symptom score (p = 0.01) and increasing PSQ scores correlated with worsening cardiac symptom scores (p = 0.006). Increasing PSQ scores also correlated with worsening school performance (p = 0.001). No differences were seen in ECG data. The screened prevalence of SDB in the pediatric population with TOF is higher than in the general population; patients with TOF and SDB are more likely to have worse cardiac symptoms and poor school performance.

Sudden cardiac death

Sudden cardiac death is often due to a ventricular arrhythmia. When a patient presents with a malignant arrhythmia unrelated to a transient reversible cause, there is a high probability of recurrent arrhythmia and sudden death. Clinical trials have shown a uniform survival benefit from implantable cardioverter-defibrillator (ICD) therapy in survivors of a malignant arrhythmia when compared with drug therapy. However, only 1% to 5% of patients survive an out-of-hospital cardiac arrest, emphasizing the need for primary prevention of sudden death. Clinical trial data available in this regard are largely limited to patients with coronary artery disease (CAD). Mortality can be reduced by the ICD in patients with CAD and depressed left ventricular ejection fraction (LVEF) less than 30%. If left ventricular function is only moderately depressed (LVEF between 30% and 40%), the presence of nonsustained ventricular tachycardia with inducible ventricular arrhythmia at electrophysiologic testing identifies patients who benefit from an ICD. The role of the ICD in primary prevention of sudden death in patients with nonischemic dilated cardiomyopathy is less clear at this time. Preliminary data indicate that the presence of heart failure symptoms in this population increases risk of sudden death that can be prevented by an ICD. Antiarrhythmic drugs have little role in prevention of sudden death; however, drugs that block the effects of beta-adrenergic stimulation, angiotensin, and aldosterone reduce mortality partly through their salutary effects on sudden death. Finally, a number of inherited defects of genes coding for ion channels, contractile sarcomeric proteins, and cell-to-cell junction proteins can result in primary electrical abnormalities and sudden death. The ICD is effective for secondary prevention, but its role in primary prevention is controversial and should be based on individual risk factors.

Congenital heart disease never goes away, even when it has been 'treated': the adult with congenital heart disease

PURPOSE OF REVIEW

As the specialties of pediatrics and pediatric cardiology continue to forge ahead with better diagnoses, medical care, and surgical results, an expanding population of patients with congenital heart disease (CHD) outgrows the pediatric age group, yet does not quite graduate to routine adult cardiology or general medicine. The adult with congenital heart disease (ACHD) faces medical, surgical, and psychosocial issues that are unique to this population and must be addressed as such. This review attempts to discuss and highlight some of the important advances and controversies brought up in the past year, in the care and management of these patients.

RECENT FINDINGS

The past five to 10 years have seen dynamic interest in understanding sequelae of corrected, uncorrected, or palliated congenital heart disease. The search for the ideal surgery, optimal prosthesis, and a smooth transition to adult care continues and is reflected in the vast amount of academic work and publications in this field. Of particular interest, conduit reoperations and single ventricle pathway modifications are still an art and a science in evolution.

SUMMARY

While all are agreed that there is a pressing need to focus on the delivery of care to the adult with congenital heart disease, this essentially requires a clearer understanding of late sequelae of CHD. The sheer heterogeneity of anatomy, age, surgery, and institutional management protocols can make it difficult to develop clear guidelines. This review attempts to give an up-to-date perspective on some of the new findings related to the more common lesions and problems faced in this group.