Regional wall motion and abnormalities of electrical depolarization and repolarization in patients after surgical repair of tetralogy of Fallot

Right ventricular regional deformation analysis in patients operated for tetralogy of Fallot

PURPOSE

We aimed to compare the findings of a segmental speckle-tracking strain of right ventricle with those of cardiac magnetic resonance imaging in this setting.

METHODS

In 26 patients with operated tetralogy of Fallot (mean age, 15.35 ± 2.3 years; range 11-18 years), right ventricular segmental speckle-straining (the basal, mid, apical segments of right ventricular septum and lateral free wall, and right ventricular apex) were determined using two-dimensional echocardiography. The echocardiographic findings were compared to right ventricular ejection fraction, right ventricular indexed end-diastolic volume, indexed end-systolic volume and pulmonary regurgitation fraction at cardiac magnetic resonance.

RESULTS

Right ventricular global speckle strain was -18.6 ± 3.7and lateral free wall strain was -17.8 ± 4.9. Indexed right ventricular end diastolic volume was 171.7 ± 23.3 ml/m², indexed right ventricular end systolic volume was 95.1 ± 35.0 ml/m² and right ventricular ejection fraction was 44.76 ± 9.39%. Basal inferior septum is correlated with indexed right ventricular end-diastolic volume (RVEDV; r = -0.521, p = 0.015) and pulmonary regurgitation fraction (r = -0.584, p = 0.015). Cardiac magnetic resonance (CMR)-derived RVEDV is correlated with lateral free wall (r = -0.465, p = 0.034) and Global RV (r = 0.442, p = 0.045).

CONCLUSION

Right ventricular basal inferior septal and apical longitudinal strain correlates with the measures of right ventricular performance on CMR. These parameters would be useful to monitor right ventricular performance in patients after tetralogy of Fallot repair.

Relative Impact of Right Ventricular Electromechanical Dyssynchrony Versus Pulmonary Regurgitation on Right Ventricular Dysfunction and Exercise Intolerance in Patients After Repair of Tetralogy of Fallot

Background The relative impact of right ventricular ( RV ) electromechanical dyssynchrony versus pulmonary regurgitation ( PR ) on exercise capacity and RV function after tetralogy of Fallot repair is unknown. We aimed to delineate the relative effects of these factors on RV function and exercise capacity. Methods and Results We retrospectively analyzed 81 children with tetralogy of Fallot repair using multivariable regression. Predictor parameters were electrocardiographic QRS duration reflecting electromechanical dyssynchrony and PR severity by cardiac magnetic resonance. The outcome parameters were exercise capacity (percentage predicted peak oxygen consumption) and cardiac magnetic resonance ejection fraction (RV ejection fraction). To understand the relative effects of RV dyssynchrony versus PR on exercise capacity and RV function, virtual patient simulations were performed using a closed-loop cardiovascular system model (CircAdapt), covering a wide spectrum of disease severity. Eighty-one patients with tetralogy of Fallot repair (median [interquartile range { IQR} ] age, 14.48 [11.55-15.91] years) were analyzed. All had prolonged QRS duration (median [IQR], 144 [123-152] ms), at least moderate PR (median [IQR], 40% [29%-48%]), reduced exercise capacity (median [IQR], 79% [68%-92%] predicted peak oxygen consumption), and reduced RV ejection fraction (median [IQR], 48% [44%-52%]). Longer QRS duration, more than PR , was associated with lower oxygen consumption and lower RV ejection fraction. In a multivariable regression analysis, oxygen consumption decreased with both increasing QRS duration and PR severity. CircAdapt modeling showed that RV dyssynchrony exerts a stronger limiting effect on exercise capacity and on RV ejection fraction than does PR , regardless of contractile function. Conclusions In both patient data and computer simulations, RV dyssynchrony, more than PR , appears to be associated with reduced exercise capacity and RV systolic dysfunction in patients after TOF repair.

Current outcomes and treatment of tetralogy of Fallot

Tetralogy of Fallot (ToF) is the most common type of cyanotic congenital heart disease. Since the first surgical repair in 1954, treatment has continuously improved. The treatment strategies currently used in the treatment of ToF result in excellent long-term survival (30 year survival ranges from 68.5% to 90.5%). However, residual problems such as right ventricular outflow tract obstruction, pulmonary regurgitation, and (ventricular) arrhythmia are common and often require re-interventions. Right ventricular dysfunction can be seen following longstanding pulmonary regurgitation and/or stenosis. Performing pulmonary valve replacement or relief of pulmonary stenosis before irreversible right ventricular dysfunction occurs is important, but determining the optimal timing of pulmonary valve replacement is challenging for several reasons. The biological mechanisms underlying dysfunction of the right ventricle as seen in longstanding pulmonary regurgitation are poorly understood. Different methods of assessing the right ventricle are used to predict impending dysfunction. The atrioventricular, ventriculo-arterial and interventricular interactions of the right ventricle play an important role in right ventricle performance, but are not fully elucidated. In this review we present a brief overview of the history of ToF, describe the treatment strategies currently used, and outline the long-term survival, residual lesions, and re-interventions following repair. We discuss important remaining challenges and present the current state of the art regarding these challenges.

Cardiac Arrhythmias in Adults with Congenital Heart Disease: Pacemakers, Implantable Cardiac Defibrillators, and Cardiac Resynchronization Therapy Devices

Implanting cardiac rhythm medical devices in adults with congenital heart disease requires training in congenital heart disease. The techniques and indications for device implantation are specific to the anatomic diagnosis and state of disease progression. It often requires a team of physicians and is best performed at a specialized adult congenital heart center.

Right Ventricular Dysfunction Due to Right Ventricular Outflow Tract Patch

Doppler tissue imaging analysis was used to examine the relationship between right ventricular function and right ventricular outflow tract damage in 54 patients with repaired tetralogy of Fallot. The patients were divided into three groups: 16 in whom the right ventricular outflow tract was directly sutured (group DS), 23 who had transventricular patch repair (group TVP), and 15 who had transannular patch repair (group TAP). The control group consisted of 16 age-matched patients who underwent patch closure of a ventricular septal defect (group C). The Tei index was obtained from tricuspid and pulmonary Doppler flow velocities. The right ventricular Tei index was significantly greater in groups TVP and TAP than in group DS. Doppler tissue imaging analysis in groups TVP and TAP showed shorter myocardial systolic velocity, diastolic peak velocity, and atrial diastolic peak velocity, lower peak myocardial velocity and acceleration during isovolumic contraction, and prolonged isovolumic relaxation and contraction times compared to groups DS and C. Right ventricular dysfunction is due to the right ventricular outflow tract patch. Thus, the right ventricular outflow tract may be essential for right ventricular ejection and maintenance of right ventricular function.

Evaluation of tricuspid annular plane systolic excursion measured with cardiac MRI in children with tetralogy of Fallot

BACKGROUND

Aneurysmal dilation of the right ventricular outflow tract complicates assessment of right ventricular function in patients with repaired tetralogy of Fallot. Tricuspid annular plane systolic excursion is commonly used to estimate ejection fraction. We hypothesised that tricuspid annular plane systolic excursion measured by cardiac MRI approximates global and segmental right ventricular function, specifically right ventricular sinus ejection fraction, in children with repaired tetralogy of Fallot.

METHODS

Tricuspid annular plane systolic excursion was measured retrospectively on cardiac MRIs in 54 patients with repaired tetralogy of Fallot. Values were compared with right ventricular global, sinus, and infundibular ejection fractions. Tricuspid annular plane systolic excursion was indexed to body surface area, converted into a fractional value, and converted into published paediatric Z-scores.

RESULTS

Tricuspid annular plane systolic excursion measurements had good agreement between observers. Right ventricular ejection fraction did not correlate with the absolute or indexed tricuspid annular plane systolic excursion and correlated weakly with fractional tricuspid annular plane systolic excursion (r=0.41 and p=0.002). Segmental right ventricular function did not appreciably improve correlation with any of the tricuspid annular plane systolic excursion measures. Paediatric Z-scores were unable to differentiate patients with normal and abnormal right ventricular function.

CONCLUSIONS

Tricuspid annular plane systolic excursion measured by cardiac MRI correlates poorly with global and segmental right ventricular ejection fraction in children with repaired tetralogy of Fallot. Tricuspid annular plane systolic excursion is an unreliable approximation of right ventricular function in this patient population.

Myocardial Tissue Doppler Velocity in Child Growth

Background

In adults, tissue Doppler imaging (TDI) is a recommended component of routine echocardiography. However, TDI velocities are less accepted in pediatrics, due to their strong variability and age dependence in children. This study examines the distribution of myocardial tissue Doppler velocities in healthy children to assess the effect of age with cardiac growth on the various echocardiographic measurements.

Methods

Total 144 healthy children were enrolled in this study. They were recruited from the pediatric outpatient clinic for routine well-child visits. The statistical relationships between age and TDI values were analyzed. Also, the statistical relationships between body surface area (BSA) and TDI values, left ventricle end-diastolic dimension (LVEDD) and TDI values were analyzed. Also, we conducted multivariate analysis of cardiac growth parameters such as, age, BSA, LVEDD and TDI velocity data.

Results

All of the age, BSA, and LVEDD had positive correlations with deceleration time (DT), pressure half-time (PHT), peak early diastolic myocardial velocity, peak systolic myocardial velocity, and had negative correlations with peak late diastolic velocity (A) and the ratio of trans-mitral inflow velocity to early diastolic velocity of mitral annulus (E/E'). In the multivariate analysis, all of the age, BSA, and LVEDD had positive correlations with DT, PHT, and negative correlations with A and E/E'.

Conclusion

The cardiac growth parameters related alterations of E/E' may suggest that diastolic myocardial velocities are cardiac growth dependent, and diastolic function has positive correlation with cardiac growth in pediatric group. This cardiac growth related myocardial functional variation would be important for assessment of cardiac involvement either in healthy and sick child.

Prolonged repolarization in atrial septal defect: An example of mechanoelectrical feedback due to right ventricular volume overload

BACKGROUND

Prolonged corrected QT (QTc) intervals are frequently observed in children before atrial septal defect (ASD) closure in our department.

OBJECTIVE

The aim of the study was to assess the effect of long-term right ventricular volume overload on repolarization.

METHODS

QRS, QT, and JT intervals were measured manually in leads II and V5 of a standard 12-lead electrocardiogram in 45 children with an isolated ASD a day before and at least 6 months after ASD closure. QT intervals were corrected for heart rate using the Bazett, Fridericia, Framingham, and Hodges formulas. Each QTc interval calculated using the Bazett formula was compared to sex- and age-matched normal values.

RESULTS

Individual QTc intervals shortened significantly (P < .001) using all correction formulas, whereas the QRS duration did not change. The prevalence of prolonged QTc interval decreased from 22.2% to 2.2% after shunt closure (P = .007).

CONCLUSION

The QTc interval shortens significantly after the closure of a hemodynamically relevant ASD in childhood. This phenomenon is independent of the used QT correction formula and may reflect a mechanoelectrical feedback associated with right ventricular volume overload.

Heart Failure Summit Review: cardiac re-synchronisation therapy in the failing heart

Extrapolating cardiac resynchronization therapy (CRT) to pediatric patients with heart failure has at times been difficult given the heterogeneity of pediatric cardiomyopathies, varying congenital heart disease (CHD) substrates, and the fact that most pediatric heart failure patients have right bundle branch block (RBBB) as opposed to LBBB. Yet, despite these limitations a number of multi-center retrospective studies in North America and Europe have identified some data to suggest that certain sub-populations tend to respond positively to CRT. In order to address some of the heterogeneity it is helpful to subdivide pediatric and young adult patients with CHD into four potential groups: (1) CRT for chronic RV pacing, (2) dilated cardiomyopathies, (3) pulmonary right ventricles, and (4) systemic right ventricles. The chronic RV paced group, especially long-standing RV apical pacing, with ventricular dyssynchrony has consistently shown to be the group that best responds to a proactive resynchronization course. CRT therapy in pulmonary right ventricles such as post-op tetralogy of Fallot have shown some promise and may be considered especially if there is evidence of concomitant left ventricular dysfunction with an electrical dyssynchrony. Patients with systemic right ventricles such as post-atrial baffle surgery or congenitally corrected transposition reportedly do well with CRT in the presence of both inter-ventricular and intra-ventricular dyssynchrony. There is little doubt that moving forward to best way to identify which pediatric patients with heart failure will respond to CRT, will require a collaborative effort between the electrophysiologist and the echocardiographer to identify appropriate candidates with electrical and mechanical dyssynchrony.

Regional analysis of longitudinal systolic function of the right ventricle after corrective surgery of tetralogy of Fallot using myocardial isovolumetric acceleration index

To assess regional longitudinal systolic function of the right ventricle in patients with repaired tetralogy of Fallot (TOF) by tissue Doppler imaging-derived isovolumetric acceleration (IVA) index and determine the effect of right-ventricular (RV) enlargement on regional systolic function. In 30 consecutive TOF patients and 30 age-matched controls, myocardial velocity of the RV ventricular free wall in the basal and middle regions were examined in the apical four-chamber view. Peak myocardial velocity during IVA was recorded on the free RV wall. IVA index was calculated as the difference between baseline and peak velocity divided by their time interval. In 23 of the studied TOF patients, magnetic resonance imaging was performed on the same day to determine global RV volume and ejection fraction. IVA index of the RV lateral free wall was significantly lower in the basal (8.31 ± 6.00 vs. 19.00 ± 10.85 m/s(2), p = 0.0001) and middle segments (6.56 ± 5.22 vs. 16.17 ± 7.44 m/s(2), p = 0.0001) in patients than in controls. Among TOF patients, a negative correlation was found between IVA index in the middle segment and RV end-diastolic volume/body surface area (r = -0.549, p < 0.01). Similar to other longitudinal RV wall parameters, the IVA index showed a decreased value in the RV free wall, which is related to the impaired regional and global longitudinal RV systolic dysfunction. RV enlargement adversely affects regional longitudinal systolic function.

Patients with repaired tetralogy of Fallot suffer from intra- and inter-ventricular cardiac dyssynchrony: a cardiac magnetic resonance study

AIMS

Patients with repaired tetralogy of Fallot (rTOF) frequently have right bundle branch block. To better understand the contribution of cardiac dyssynchrony to dysfunction, we developed a method to quantify left (LV), right (RV), and inter-ventricular dyssynchrony using standard cine cardiac magnetic resonance (CMR).

METHODS AND RESULTS

Thirty patients with rTOF and 17 healthy controls underwent cine CMR. Patients were imaged twice to assess inter-test reproducibility. Circumferential strain curves were generated with a custom feature-tracking algorithm for 12 LV and 12 RV segments in each of 4-7 short-axis slices encompassing the ventricles. Temporal offsets (TOs, in ms) of the strain curves relative to a patient-specific reference curve were calculated. The intra-ventricular dyssynchrony index (DI) for each ventricle was computed as the standard deviation of the TOs. The inter-ventricular DI was calculated as the difference in median RV and median LV TOs. Compared with controls, patients had a greater LV DI (21 ± 8 vs. 11 ± 5 ms, P < 0.001) and RV DI (60 ± 19 vs. 47 ± 17 ms, P = 0.02). RV contraction was globally delayed in patients, resulting in a greater inter-ventricular DI with the RV contracting 45 ± 25 ms later than the LV vs. 12 ± 29 ms earlier in controls (P < 0.001). Inter-test reproducibility was moderate with all coefficients of variation ≤22%. Both LV and RV DIs were correlated with measures of LV, but not RV, function.

CONCLUSION

Patients with rTOF have intra- and inter-ventricular dyssynchrony, which can be quantified from standard cine CMR. This new approach can potentially help determine the contribution of dyssynchrony to ventricular dysfunction in future studies.

Percutaneous implantation of pulmonary valves

Percutaneous implantation of valves is evolving as the most exciting innovation in transcatheter therapeutics. Valve repairs and replacements form an important indication of re-operations after congenital heart operations. Right ventricular outflow tract surgery is common after repair of conditions such as pulmonary atresia with Tetralogy of Fallot, common arterial trunk and Rastelli operation for transposition of great arteries, ventricular septal defect with pulmonary stenosis. Conduit survival is improving, nevertheless, re-operations are common. Although the re-operations can be performed at low risk, they still involve morbidity and mortality. Percutaneous implantation of valves is emerging as an alternative option for these group of patients. Our experience in percutaneous implantation of pulmonary valves has yielded encouraging results. For incompetence, the results are excellent. Evolving technology is making it applicable in wider clinical situations. Similar technology could also be applied to implantation of valves in the aortic position.

Arrhythmias in adult congenital heart disease

Recent advances in pediatric cardiology and cardiac surgery have allowed a rapidly expanding population of patients with congenital heart disease to thrive well into their adult years. Often after prolonged uneventful clinical courses as children and adolescents, arrhythmias may surface later in life. These arrhythmias are a major source of morbidity. In addition, sudden death is the leading cause of mortality in adult patients with congenital heart disease. This review highlights the various types of brady- and tachyarrhythmias encountered in the more common forms of adult congenital heart disease and explores prognostic implications and therapeutic options.

Clinical research priorities in adult congenital heart disease

BACKGROUND

Adult congenital heart disease (ACHD) clinicians are hampered by the paucity of data to inform clinical decision-making. The objective of this study was to identify priorities for clinical research in ACHD.

METHODS

A list of 45 research questions was developed by the Alliance for Adult Research in Congenital Cardiology (AARCC), compiled into a survey, and administered to ACHD providers. Patient input was sought via the Adult Congenital Heart Association at community meetings and online forums. The 25 top questions were sent to ACHD providers worldwide via an online survey. Each question was ranked based on perceived priority and weighted based on time spent in ACHD care. The top 10 topics identified are presented and discussed.

RESULTS

The final online survey yielded 139 responses. Top priority questions related to tetralogy of Fallot (timing of pulmonary valve replacement and criteria for primary prevention ICDs), patients with systemic right ventricles (determining the optimal echocardiographic techniques for measuring right ventricular function, and indications for tricuspid valve replacement and primary prevention ICDs), and single ventricle/Fontan patients (role of pulmonary vasodilators, optimal anticoagulation, medical therapy for preservation of ventricular function, treatment for protein losing enteropathy). In addition, establishing criteria to refer ACHD patients for cardiac transplantation was deemed a priority.

CONCLUSIONS

The ACHD field is in need of prospective research to address fundamental clinical questions. It is hoped that this methodical consultation process will inform researchers and funding organizations about clinical research topics deemed to be of high priority.

Management of arrhythmias in patients with a tetralogy of Fallot

Although arrhythmias are commonly found in patients with all different types of congenital heart disease, perhaps no patient is at higher risk of late development of arrhythmias that may result in sudden death than in the patient following tetralogy of Fallot repair. Despite major improvement in the surgical repair of this disease, a significant percentage of these patients continue to remain at risk for the late development of arrhythmias, and a small percentage will develop life-threatening arrhythmias and sudden death. Which patients remain at highest risk is still not clearly delineated. Diligent arrhythmia surveillance and aggressive treatment strategies are necessary to minimise this risk. This article highlights important strategies to manage arrhythmia development and prevention in this patient population.

Relation of right ventricular mechanics to exercise tolerance in children after tetralogy of Fallot repair

BACKGROUND

Progressive right ventricular (RV) dysfunction and exercise intolerance are common problems after tetralogy of Fallot (TOF) repair. We investigated RV myocardial deformation and dyssynchrony in children after TOF repair and their association with exercise capacity.

METHODS

Asymptomatic children after TOF repair were investigated by 2-dimensional speckle tracking echocardiography, magnetic resonance, and metabolic exercise study. Patients with RV outflow obstruction were excluded. Peak RV longitudinal strain and strain rate (SR) and dyssynchrony (RV intraventricular delay) were compared with healthy controls. Associations between RV strain, dyssynchrony, and exercise capacity were analyzed.

RESULTS

Thirty-nine (81%) of 48 TOF patients and 40 healthy controls had adequate RV strain imaging. The TOF patients had moderately dilated RVs and normal RV ejection fraction. Right ventricular peak systolic strain (-23.2% ± 5.1% vs -28.5% ± 8.5%, P < .001) and SR (-1.46 ± 0.68 vs -2.1 ± 0.8, P < .001) were reduced in TOF patients compared with controls. Right ventricular intraventricular delay was higher in TOF patients (146.0 ± 159 vs 71.0 ± 92 milliseconds, P = .008). Decreased RV strain and SR were associated with increased RV dyssynchrony (strain parameter estimate [PE] 6.31 [2.30], P = .007; SR [PE] 11.32 [3.84], P = .004). Increased RV-left ventricular delay was associated with prolonged QRS duration (PE 0.13 [0.058], P = .03) and reduced RV ejection fraction (PE -2.95 [1.275], P = .02). Reduced RV peak SR was associated with decreased exercise peak oxygen uptake (PE 0.14 [0.07], P = .04).

CONCLUSIONS

After repair of TOF, asymptomatic children have reduced RV deformation in association with RV dyssynchrony and reduced exercise tolerance.

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.

Quantifying pulmonary regurgitation and right ventricular function in surgically repaired tetralogy of Fallot: a comparative analysis of echocardiography and magnetic resonance imaging

BACKGROUND

Patients with repaired tetralogy of Fallot are monitored for pulmonary regurgitation (PR) and right ventricular (RV) function. We sought to compare measures of PR and RV function on echocardiogram to those on cardiac magnetic resonance (CMR) and to develop a new tool for assessing PR by echocardiogram.

METHODS AND RESULTS

Patients with repaired tetralogy of Fallot (n=143; 12.5±3.2 years) had an echocardiogram and CMR within 3 months of each other. On echocardiogram, RV function was assessed by (1) Doppler tissue imaging of the RV free wall and (2) myocardial performance index. The ratio of diastolic and systolic time-velocity integrals measured by Doppler of the main pulmonary artery was calculated. CMR variables included RV ejection fraction, RV volumes, and pulmonary regurgitant fraction (RF). Pulmonary regurgitation was graded as mild (RF<20%), moderate (RF=20-40%), and severe (RF>40%). On CMR, RF was 34+17% and RV ejection fraction was 61+8%. Echocardiography had good sensitivity identifying cases with RF>20% (sensitivity 97%; 95% CI: 92-99%) but overestimated the amount of PR when RF<20% (false-positive rate 36%; 95% CI: 18-57%). The diastolic and systolic time-velocity integrals on echocardiogram showed moderate correlation with RF on CMR (R=0.60; P<0.0001). On CMR, RF of 20% and 40% corresponded with a diastolic and systolic time-velocity integral of 0.49 (95% CI: 0.44-0.56) and 0.72 (95% CI: 0.68-0.76), respectively. RV myocardial performance index correlated modestly with RV ejection fraction (r=-0.33; P<0.001).

CONCLUSIONS

This study suggests that the diastolic and systolic time-velocity integrals ratio may make a modest contribution to the overall assessment of PR in patients with repaired tetralogy of Fallot and warrants further investigation. However, echocardiography continues to have a limited ability to quantify PR and RV function as compared with CMR.

Transthoracic echocardiography in children and young adults with congenital heart disease

Transthoracic echocardiography (TTE) is the first-line tool for diagnosis and followup of pediatric and young adult patients with congenital heart disease (CHD). Appropriate use of TTE can reduce the need for more invasive modalities, such as cardiac catheterization and cardiac magnetic resonance imaging. New echocardiographic techniques have emerged more recently: tissue Doppler imaging, tissue tracking (strain and strain rate), vector velocity imaging (VVI), myocardial performance index, myocardial acceleration during isovolumic acceleration (IVA), the ratio of systolic to diastolic duration (S/D ratio), and two dimensional measurements of systolic right ventricular (RV) function (e.g., tricuspid annular plane systolic excursion, TAPSE). These may become valuable indicators of ventricular performance, compliance, and disease progression. In addition, three-dimensional (3D) echocardiography when performed for the assessment of valvular function, device position, and ventricular volumes is being integrated into routine clinical care. In this paper, the potential use and limitations of these new echocardiographic techniques in patients with CHD are discussed. A particular focus is on the echocardiographic assessment of right ventricular (RV) function in conditions associated with increased right ventricular volume (e.g., pulmonary regurgitation after tetralogy of Fallot repair) or pressure (e.g., pulmonary hypertension) in children and young adults.

The Right Heart in Congenital Heart Disease, Mechanisms and Recent Advances

In patients with congenital heart disease, the right heart may support the pulmonary or the systemic circulation. Several congenital heart diseases primarily affect the right heart including Tetralogy of Fallot, transposition of great arteries, septal defects leading to pulmonary vascular disease, Ebstein anomaly and arrhythmogenic right ventricular cardiomyopathy. In these patients, right ventricular dysfunction leads to considerable morbidity and mortality. In this paper, our objective is to review the mechanisms and management of right heart failure associated with congenital heart disease. We will outline pearls and pitfalls in the management of congenital heart disease affecting the right heart and highlight recent advances in the field.

Non-Invasive Imaging for Congenital Heart Disease: Recent Innovations in Transthoracic Echocardiography

Transthoracic echocardiography (TTE) is an important tool for diagnosis and follow-up of patients with congenital heart disease (CHD). Appropriate use of TTE can reduce the need for more invasive and complex modalities, such as cardiac catheterization and cardiac magnetic resonance imaging. New echocardiographic techniques have emerged for the assessment of ventricular systolic and diastolic function: Tissue Doppler imaging, tissue tracking, strain and strain rate imaging, vector velocity imaging (VVI), myocardial performance index, myocardial acceleration during isovolumic contraction (IVA), the ratio of systolic to diastolic duration (S/D ratio), and other measurements of systolic right ventricular (RV) function like tricuspid annular plane systolic excursion (TAPSE). These modalities may become valuable indicators of ventricular performance, compliance and disease progression, with the caveat of preload-dependency of the variables measured. In addition, three-dimensional (3D) echocardiography for the assessment of cardiac anatomy, valvular function, device position, ventricular volumes and ejection fraction is integrated into routine clinical care. In this review, we discuss the potential use and limitations of these new echocardiographic techniques in patients with CHD. A particular focus is on the echocardiographic assessment of right ventricular (RV) function by means of tissue Doppler imaging, tissue tracking, and three-dimensional imaging, in conditions associated with increased right ventricular volume or pressure load.

The impact of pulmonary regurgitation on right ventricular regional myocardial function: an echocardiographic study in adults after total repair of tetralogy of Fallot

BACKGROUND

Early results of tetralogy of Fallot (TOF) surgical repair are excellent, but patients are at risk for long-term complications. The purpose of the study was to determine to what extent ultrasonic tissue indices can be helpful in assessing the degree of pulmonary regurgitation (PR).

METHODS

Fifty adults (26 men, 24 women; mean age, 34.4 years) who had undergone TOF correction were studied.

RESULTS

Compared with normal controls, patients had decreased tricuspid annular plane systolic excursion (20.66 vs 26.79 mm, P < .05). In patients with TOF, maximal strain was reduced in all right ventricular free wall and interventricular septal segments. In patients with previous palliative shunts, lower maximal strain for RV basal segment was observed compared with subjects with no palliative surgery (-18.22% vs -22.27%, P < .05). Maximal systolic and early diastolic strain and strain rate values were significantly higher in patients with PR widths ≥ 3 mm compared with patients with PR widths < 3 mm.

CONCLUSIONS

Adults after TOF repair have decreased regional deformation of the right ventricle and intraventricular septum. Prior palliative treatment reduces the indices of right ventricular regional deformation. PR severity can be described by the extent of right ventricular regional deformation.

Acute Cardiac Resynchronization Therapy for the Failing Left, Right, or Single Ventricle After Repaired Congenital Heart Disease

Use of cardiac resynchronization in children and young adults with congenital heart disease has been described in a variety of anecdotal cases and pooled institutional summaries which report mid-term results. This manuscript addresses use of cardiac resynchronization and/or multisite pacing in children in the acute postoperative period with a failing right, left, or single ventricle.

Echocardiography as a hemodynamic monitor in critically ill children

Echocardiography is a widely used modality to assess myocardial structure and function in pediatric intensive care settings. While the use of echocardiography for diagnostic purposes remains important, its use as a hemodynamic monitoring tool has not been well established. The benefits of echocardiography are in its widespread availability, relative ease of use, and importance in diagnosing structural disease and simple changes in myocardial function. However, echocardiography in pediatric critical care is limited in its use because it requires the acquisition of quality images and the accurate interpretation of the study. To date, the literature on echocardiography in pediatric critical care is limited. The purpose of this review is to examine the scientific evidence for the usefulness of echocardiography as a hemodynamic monitoring tool in pediatric critical care.

Relation of left ventricular dyssynchrony measured by cardiac magnetic resonance tissue tracking in repaired tetralogy of fallot to ventricular tachycardia and death

The impact of left ventricular (LV) dyssynchrony on clinical outcomes in patients with tetralogy of Fallot (TOF) is unknown. The aim of this study was to test the hypothesis that LV dyssynchrony assessed by cardiac magnetic resonance (CMR)-derived tissue tracking in patients with repaired TOF is associated with ventricular tachycardia (VT) and death. Included patients had repaired TOF and CMR data from 2000 and 2008. Patients (n = 13) had histories of death or sustained VT. Control subjects (n = 26), with no death or VT, were matched by age at CMR and type of last surgical procedure. Demographic, clinical, and electrocardiographic data were recorded. CMR short-axis cine data were analyzed by tracking the motion of the endocardial border using commercial software. LV dyssynchrony was quantified as the maximum difference in time to peak radial displacement, circumferential strain, and radial strain among the 6 ventricular segments and the standard deviation of the times to peak value. There were no differences between groups in clinical, electrocardiographic, or demographic characteristics. Among CMR parameters, right ventricular volumes were higher and ejection fractions lower in the patient group. Indexes of LV dyssynchrony were higher in the patient group (e.g., maximum time difference of circumferential strain 94 vs 46 ms, p <0.001; standard deviation of circumferential strain 37.8 vs 20.3 ms, p <0.01). In a multivariate model including LV synchrony variables, the best outcome discriminator was maximum time difference to peak circumferential strain (p <0.01). In conclusion, tissue tracking applied to CMR images identifies indexes of LV synchrony associated with death and VT in patients with repaired TOF.

Increased microvolt T-wave alternans in patients with repaired tetralogy of Fallot

BACKGROUND

Microvolt T wave alternans (MTWA) is an indicator of repolarization heterogeneity and a predictor of ventricular arrhythmia in adults with ischemic or dilated cardiomyopathy. Its implication in patients with repaired tetralogy of Fallot (TOF) is still unclear. This study sought to define the changes and the clinical implication of MTWA in these patients.

METHODS

Treadmill examination with modified moving average beat analysis (MMA) for MTWA was performed in 101 repaired TOF patients (60.4% male). Data from 103 age- and sex-matched subjects with normal hearts served as controls.

RESULTS

The age at latest follow-up was 20.0 ± 10.6 years. Total repair (60.4% received a transannular right ventricular outflow patch) was performed at a mean age of 4.8(± 5.8) years. After excluding 11 patients with indeterminate data, the MTWA data in 90 TOF patients revealed higher values than those in the control (25.1 ± 14.0 vs. 17.6 ± 9.2 μV, p<0.001). The values were best correlated to the presence of severe pulmonary regurgitation (p=0.006). Ten (9.9%) patients experienced late ventricular arrhythmic events. They tended to have higher MTWA values than those without (34.0 ± 16.5 vs. 24.2 ± 13.5 and p=0.053). Although the MTWA per se would not predict the late arrhythmia events better than QRS duration alone, the positive and negative predictive values increased slightly after adding the MTWA to QRS duration.

CONCLUSIONS

MTWA, as measured by MMA, increased in repaired TOF patients particularly in those with severe pulmonary regurgitation and late arrhythmia events. To predict late ventricular arrhythmia, MTWA however was not superior to QRS duration alone.

Pulmonary valve replacement in adults with repaired tetralogy of Fallot

There is a growing population of young adults with tetralogy of Fallot. Although surgical approaches have evolved, many adults with repaired tetralogy of Fallot have been left with residual pulmonary regurgitation. Pulmonary regurgitation is an important contributor to a number of late complications including exercise limitations, right heart failure, arrhythmia, and sudden death. Because bioprosthetic valves are used in this population, clinicians must weigh the beneficial effects of pulmonary valve replacement against the associated risks, including subsequent re-operation. In this review, we will appraise the evidence supporting pulmonary valve replacement in the adult with repaired tetralogy of Fallot, as well as the optimal timing and mode of intervention.

Unnatural history of the right ventricle in patients with congenitally malformed hearts

The long-term outcome of patients with congenitally malformed hearts involving abnormal right ventricular morphology and haemodynamics is variable. In most instances, the patients are at risk for right ventricular failure, in part due to morphological differences between the right and left ventricles and their response to chronic volume and pressure overload. In patients after repair of tetralogy of Fallot, and after balloon valvotomy for valvar pulmonary stenosis, pulmonary regurgitation is the most significant risk factor for right ventricular dysfunction. In patients with a dominant right ventricle after Fontan palliation, and in those with systemic right ventricles in association with surgically or congenitally corrected transposition, the right ventricle is not morphologically capable of dealing with chronic exposure to the high afterload of the systemic circulation. In patients with Ebstein's malformation of the tricuspid valve, the degree of atrialisation of the right ventricle determines how well the right ventricle will function as the pump for the pulmonary vascular bed.

Developments in echocardiographic techniques for the evaluation of ventricular function in children

Echocardiography is a very important tool for the diagnosis and follow-up of children with congenital and acquired heart disease. One of the challenges that remains in paediatric heart disease is the assessment of systolic and diastolic function in children, as this is influenced by growth, morphology and loading conditions. New echocardiographic techniques, such as tissue Doppler, deformation imaging and three-dimensional echocardiography, have great potential application in this field. They may provide new insights into the influence of growth, morphology and loading on cardiac mechanics, and could become useful clinical tools. In this review, we discuss the potential use and limitations of these new echocardiographic techniques in paediatric and congenital heart disease.

Validation of an animal model of right ventricular dysfunction and right bundle branch block to create close physiology to postoperative tetralogy of Fallot

BACKGROUND

In the past 5 years a few number of studies and case reports have come out focusing on biventricular (BiV) stimulation for treatment of congenital heart disease related ventricular dysfunction. The few available studies include a diverse group of pathophysiological entities ranging from a previously repaired tetralogy of Fallot (TOF) to a functional single ventricle anatomy. Patient's status is too heterogeneous to build important prospective study. To well understand the implication of prolonged electromechanical dyssynchrony we performed a chronic animal model that mimics essential parameters of postoperative TOF.

METHODS

Significant pulmonary regurgitation, mild stenosis, as well as right ventricular outflow tract (RVOT) scars were induced in 15 piglets to mimic repaired TOF. 4 months after hemodynamics and dyssynchrony parameters were compared with a control group and with a population of symptomatic adult with repaired TOF.

RESULTS

Comparing the animal model with the animal control group on echocardiography, RV dilatation, RV and LV dysfunction, broad QRS complex and dyssynchrony were observed on the animal model piglets. Moreover, epicardial electrical mapping showed activation consistent with a right bundle branch block. The animal models displayed the same pathophysiological parameters as the post TOF repair patients in terms of QRS duration, pulmonary regurgitation biventricular dysfunction and dyssynchrony.

CONCLUSION

This chronic swine model mimics electromechanical ventricular activation delay, RV and LV dysfunction, as in adult population of repair TOF. It does appear to be a very useful and interesting model to study the implication of dyssynchrony and the interest of resynchronization therapy in TOF failing ventricle.

Diastolic dysfunction in pediatric cardiac patients: evaluation and management

OPINION STATEMENT

The heart is a complex and sophisticated pump that cycles between two phases: diastole, during which a compliant chamber (ventricle) allows the blood to fill from a reservoir chamber (atrium) of low pressure, and systole, during which a stiff chamber with rapidly rising pressure ejects the blood into an arterial circuit of high pressure. However, the systolic and diastolic cycles are not dichotomous. They have complex interactions with interrelated segments of the cardiac cycle. Although the entity of "diastolic heart failure with preserved systolic function" has been applied in adult patients, a discrete diagnosis of systolic and diastolic heart failure may be difficult to apply in pediatric patients. Advances in echocardiography have helped decipher the morphologic and physiologic expression of congenital and acquired heart disease and have increased our understanding the diastolic function and dysfunction. The evolving concept of systolic and diastolic heart failure is helping us develop a strategy for its management in pediatric patients with complex heart diseases.