Indications and timing of pulmonary valve replacement after tetralogy of Fallot repair

Right ventricular failure and pathobiology in patients with congenital heart disease - implications for long-term follow-up

Right ventricular dysfunction represents a common problem in patients with congenital heart defects, such as Tetralogy of Fallot or pulmonary arterial hypertension. Patients with congenital heart defects may present with a pressure or volume overloaded right ventricle (RV) in a bi-ventricular heart or in a single ventricular circulation in which the RV serves as systemic ventricle. Both subsets of patients are at risk of developing right ventricular failure. Obtaining functional and morphological imaging data of the right heart is technically more difficult than imaging of the left ventricle. In contrast to findings on mechanisms of left ventricular dysfunction, very little is known about the pathophysiologic alterations of the right heart. The two main causes of right ventricular dysfunction are pressure and/or volume overload of the RV. Until now, there are no appropriate models available analyzing the effects of pressure and/or volume overload on the RV. This review intends to summarize clinical aspects mainly focusing on the current research in this field. In future, there will be increasing attention to individual care of patients with right heart diseases. Hence, further investigations are essential for understanding the right ventricular pathobiology.

Survey of reoperation indications in tetralogy of fallot in Japan

BACKGROUND

Although the survival rate for repaired Tetralogy of Fallot (TOF) is dramatically improving, anatomical and functional residua and sequelae followed by arrhythmias and sudden death are still challenging issues to be resolved. Reoperation can reduce the incidence of arrhythmias and sudden death, but there is no consensus on the indications of reoperation for patients with TOF, especially in Japan.

METHODS AND RESULTS

A cross-sectional questionnaire survey of reoperation indications in patients with TOF was performed through a Japanese multicenter study. The questionnaire, which focused on the number of repaired TOF patients aged >15 years old, reoperation indications and management, was sent to the institutions belonging to Japanese Society for Adult Congenital Heart Disease. In total, 41.5% (78/188) of the institutions replied. The total number of repaired TOF patients was 4,010, and sudden cardiac death was observed in 45.236/4,010 (5.9%) experienced reoperation. Pulmonary stenosis (32%) and pulmonary regurgitation (29%) were the most common reasons for reoperation. There were only 2 implantable cardioverter defibrillator or resynchronization therapy defibrillator implantations. The physiological/anatomical indications of reoperation differed among the hospitals.

CONCLUSIONS

Approximately 1.1% of patients suffered sudden death and 6% of repaired TOF patients had reoperation. The indications of reoperation, however, varied among the institutions. Therefore, detailed information for each case of sudden death or reoperation should be collected and analyzed in order to establish guidelines for reoperation.

PINOT NOIR: pulmonic insufficiency improvement with nitric oxide inhalational response

BACKGROUND

Tetralogy of Fallot (TOF) repair and pulmonary valvotomy for pulmonary stenosis (PS) lead to progressive pulmonary insufficiency (PI), right ventricular enlargement and dysfunction. This study assessed whether pulmonary regurgitant fraction measured by cardiovascular magnetic resonance (CMR) could be reduced with inhaled nitric oxide (iNO).

METHODS

Patients with at least moderate PI by echocardiography undergoing clinically indicated CMR were prospectively enrolled. Patients with residual hemodynamic lesions were excluded. Ventricular volume and blood flow sequences were obtained at baseline and during administration of 40 ppm iNO.

RESULTS

Sixteen patients (11 with repaired TOF and 5 with repaired PS) completed the protocol with adequate data for analysis. The median age [range] was 35 [19-46] years, BMI was 26 ± 5 kg/m(2) (mean ± SD), 50% were women and 75% were in NYHA class I. Right ventricular end diastolic volume index for the cohort was 157 ± 33 mL/m(2), end systolic volume index was 93 ± 20 mL/m(2) and right ventricular ejection fraction was 40 ± 6%. Baseline pulmonary regurgitant volume was 45 ± 25 mL/beat and regurgitant fraction was 35 ± 16%. During administration of iNO, regurgitant volume was reduced by an average of 6 ± 9% (p=0.01) and regurgitant fraction was reduced by an average of 5 ± 8% (p=0.02). No significant changes were observed in ventricular indices for either the left or right ventricle.

CONCLUSION

iNO was successfully administered during CMR acquisition and appears to reduce regurgitant fraction in patients with at least moderate PI suggesting a potential role for selective pulmonary vasodilator therapy in these patients.

TRIALS REGISTRATION

ClinicalTrials.gov, NCT00543933.

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.

Pulmonary stenosis and pulmonary regurgitation: both ends of the spectrum in residual hemodynamic impairment after tetralogy of Fallot repair

Repair of tetralogy of Fallot (TOF) has shown excellent outcomes. However it leaves varying degrees of residual hemodynamic impairment, with severe pulmonary stenosis (PS) and free pulmonary regurgitation (PR) at both ends of the spectrum. Since the 1980s, studies evaluating late outcomes after TOF repair revealed the adverse impacts of residual chronic PR on RV volume and function; thus, a turnaround of operational strategies has occurred from aggressive RV outflow tract (RVOT) reconstruction for complete relief of RVOT obstruction to conservative RVOT reconstruction for limiting PR. This transformation has raised the question of how much residual PS after conservative RVOT reconstruction is acceptable. Besides, as pulmonary valve replacement (PVR) increases in patients with RV deterioration from residual PR, there is concern regarding when it should be performed. Regarding residual PS, several studies revealed that PS in addition to PR was associated with less PR and a small RV volume. This suggests that PS combined with PR makes RV diastolic property to protect against dilatation through RV hypertrophy and supports conservative RVOT enlargement despite residual PS. Also, several studies have revealed the pre-PVR threshold of RV parameters for the normalization of RV volume and function after PVR, and based on these results, the indications for PVR have been revised. Although there is no established strategy, better understanding of RV mechanics, development of new surgical and interventional techniques, and evidence for the effect of PVR on RV reverse remodeling and its late outcome will aid us to optimize the management of TOF.

Repair and follow-up of Tetralogy of Fallot with pulmonary stenosis

Tetralogy of Fallot is the most common cyanotic congenital heart defect. Advances in surgical technique and postoperative care have improved survival which is now very good. Patients now face long-term morbidities such as reduced exercise tolerance and arrthymias. Cardiologists caring for these patients are confronted with decisions regarding best care practices. This article will review the evidence available on repair and postoperative follow-up for patients with Tetralogy of Fallot with pulmonary stenosis.

Pulmonary Regurgitation after Tetralogy of Fallot Repair: A Diagnostic and Therapeutic Challenge

BACKGROUND

Pulmonary regurgitation is the key hemodynamically significant lesion in repaired tetralogy of Fallot contributing to progressive right ventricular (RV) dilatation and biventricular dysfunction. The timing for pulmonary valve replacement remains a controversial topic, and the decision to intervene depends on assessment of RV size and RV function.

OBJECTIVES

This review aims to discuss the echocardiographic techniques that can be used to assess patients with pulmonary regurgitation after the repair of tetralogy of Fallot defect. While cardiac magnetic resonance (CMR) imaging is the clinical reference method, there is an important role of echocardiography in identifying patients with significant pulmonary regurgitation and assessing the RV size and function. The different echocardiographic techniques that can be used in this context are discussed. Newer techniques for assessing RV size and function include three-dimensional (3D) echocardiography, tissue Doppler and strain imaging. 3D RV volumetric reconstruction based on two-dimensional imaging is a promising new technique that could potentially replace CMR for RV volumetric assessment.

CONCLUSIONS

Developments in echocardiographic techniques provide new insights into the impact of pulmonary regurgitation on RV structure and function. Echocardiography and CMR are complementary modalities and further research is required to define the optimal use of both techniques for this indication.

Melody valve implant within failed bioprosthetic valves in the pulmonary position: a multicenter experience

BACKGROUND

Transcatheter pulmonary valve implantation using the Melody valve has emerged as an important therapy for the treatment of postoperative right ventricular outflow tract dysfunction. Melody-in-bioprosthetic valves (BPV) is currently considered an off-label indication. We review the combined experience with transcatheter pulmonary valve implantation within BPVs from 8 centers in the United States and discuss technical aspects of the Melody-in-BPV procedure.

METHODS AND RESULTS

A total of 104 patients underwent Melody-in-BPV in the pulmonary position at 8 US centers from April 2007 to January 2012. Ten different types of BPVs were intervened on, with Melody valve implantation at the intended site in all patients. Following Melody valve implant, the peak right ventricle-to-pulmonary artery gradient decreased from 38.7 ± 16.3 to 10.9 ± 6.7 mm Hg (P<0.001), and the right ventricular systolic pressure fell from 71.6 ± 21.7 to 46.7 ± 15.9 mm Hg (P<0.001). There was no serious procedural morbidity, and no deaths related to the catheterization or implant. At a median follow-up of 12 months (1-46 months), no patients had more than mild regurgitation, and 4 had a mean right ventricular outflow tract gradient ≥30 mm Hg. During follow-up, there were 2 stent fractures, 3 cases of endocarditis (2 managed with surgical explant), and 2 deaths that were unrelated to the Melody valve.

CONCLUSIONS

Transcatheter pulmonary valve implantation using the Melody valve within BPVs can be accomplished with a high rate of success, low procedure-related morbidity and mortality, and excellent short-term results. The findings of this preliminary multicenter experience suggest that the Melody valve is an effective transcatheter treatment option for failed BPVs.

Getting personal: understanding how genetic variation affects clinical outcomes in patients with tetralogy of Fallot

The work by Jeewa et al. is an important step toward “personalizing” or individualizing our approach to care of patients with tetralogy of Fallot. Although future studies will need to confirm the potential role of HIF1A-mediated signaling in right ventricular remodeling, it raises the possibility that modulation of the HIF1A signaling pathway or its downstream effectors such as TGF-β may allow better preservation of ventricular function in patients with TOF. Furthermore, directed genotyping for HIF1A and other genetic variants may help identify patients at risk for adverse outcomes. This study demonstrates the potential for genetics-of- outcomes studies to evaluate novel therapeutic targets and to identify at-risk populations that may require specific therapeutic considerations.

Double-barrel right ventricular outflow: tetralogy of Fallot annulus preservation technique

In patients with tetralogy of Fallot (TOF) repair and a borderline pulmonary valve annulus (PVA) size, surgical repair often necessitates a transannular incision and subsequent placement of a patch with or without a monocusp or, alternatively, a right ventricle-to-pulmonary artery conduit. We discuss here a technique in which the pulmonary valve annulus can be safely preserved, with infrequent postoperative issues as well as the potential for less incidence of right ventricular outflow intervention in the long term.

Assessment of the accuracy and reproducibility of RV volume measurements by CMR in congenital heart disease

OBJECTIVES

The purpose of this study was to determine whether right ventricular (RV) volumes are more accurately and reproducibly measured by cardiac magnetic resonance (CMR) in an axial orientation or in a short-axis orientation in patients with congenital heart disease (CHD).

BACKGROUND

There is little agreement on the most suitable imaging plane for RV volumetric analysis in the setting of abnormal RV physiology.

METHODS

Measurements of RV volumes from datasets acquired in axial and short-axis orientations were made in 50 patients with CHD. RV stroke volumes (SV) calculated using these 2 methods were compared with forward flow measured in the pulmonary trunk by phase contrast (PC) imaging. Repeated volume measurements were made to assess intraobserver and interobserver reliability. Bland-Altman plots and Lin's concordance correlation coefficient (CCC) were used for all analyses of agreement.

RESULTS

Analysis of all subjects revealed a statistically significant difference in interobserver reliability of RV end-systolic volume (ESV) measurements that favored the axial method (p = 0.047). The magnitude of measurement differences between observers in this case was small (-2.8 ml/m(2); 95% confidence interval: -5.6 to 0.0). There was no difference between the 2 contouring methods in terms of intraobserver reliability in measurements of RV end-diastolic volume (EDV), ESV, ejection fraction, or SV (p > 0.05 in all cases). In subjects with RV EDV ≥ 150 ml/m(2), RV SV measured using axial contours yielded better agreement with forward flow measured in the pulmonary trunk (CCC = 0.63) than did measurements made using short-axis contours (CCC = 0.56; p = 0.007).

CONCLUSIONS

Trends favoring the axial orientation in terms of reproducibility were not clinically significant. In subjects with RV EDV ≥ 150 ml/m(2), the axial orientation yields RV volume measurements that agree more closely with flow measured in the pulmonary trunk than does the short-axis orientation.

Imaging the right heart: the use of integrated multimodality imaging

During recent years, right ventricular (RV) structure and function have been found to be an important determinant of outcome in different cardiovascular and also pulmonary diseases. Currently, echocardiography and cardiac magnetic resonance (CMR) imaging are the two imaging modalities most commonly used to visualize the RV. Most structural abnormalities of the RV can be reliably described by echocardiography but due its complex geometrical shape, echocardiographic assessment of RV function is more challenging. Newer promising echocardiographic techniques are emerging but lack of validation and limited normal reference data influence their routine clinical application. Cardiac magnetic resonance is generally considered the clinical reference technique due to its unlimited imaging planes, superior image resolution, and three-dimensional volumetric rendering. The accuracy and reliability of CMR measurements make it the ideal tool for serial examinations of RV function. Multidetector computed tomography (MDCT) plays an important role in the diagnosis of pulmonary emboli but can also be used for assessing RV ischaemic disease or as an alternative for CMR if contra-indicated. Radionuclide techniques have become more obsolete in the current era. The different imaging modalities should be considered complimentary and each plays a role for different indications.

The cause of B-type natriuretic peptide elevation and the dose-dependent effect of angiotensin-converting enzyme inhibitor on patients late after tetralogy of Fallot repair

Patients after surgical repair of tetralogy of Fallot (TOF) may experience various complications that result in neurohormonal activation, including plasma B-type natriuretic peptide (BNP) elevation. Right ventricular (RV) dilation is a frequent complication, and few treatments are available. This study aimed to identify the factor or factors leading to BNP elevation and to clarify the effects of angiotensin-converting enzyme inhibitor (ACE-I) on changes in BNP levels in patients with repaired TOF. Plasma BNP levels and hemodynamic data derived from cardiac catheterization were analyzed. In addition, longitudinal BNP levels and ACE-I dosages were analyzed for patients administered ACE-I. For 31 patients with repaired TOF, who mainly had RV dilation, log BNP levels were significantly correlated with the RV end-diastolic volume index (P = 0.02) as well as ventricular volume and pressure (P < 0.01). For 11 patients medicated with ACE-I, BNP levels were significantly lower at the time of maximal ACE-I dosage than at the time of minimal dosage (P < 0.01). Furthermore, BNP levels decreased as the ACE-I dosage per body weight increased (P < 0.01). In conclusion, elevation of BNP in patients after TOF repair could reflect volume and pressure load in the RV end-diastolic phase, and ACE-I may reduce BNP levels in a dose-dependent manner.

Tetralogy of Fallot: perioperative anesthetic management of children and adults

Tetralogy of Fallot (TOF) is a common congenital heart defect in children. Perioperative considerations include preoperative preparation for surgery, intraoperative anesthetic management, and common postoperative issues in the intensive care unit. Surgical debates have shifted away from 2-stage versus single-stage repairs to debates of how surgery to limit pulmonary insufficiency (PI) may have significant long-term impact as the child grows. There are many adult survivors of TOF repair in infancy who now present with a unique set of problems related to PI and right ventricular dysfunction. These adults provide new insights into congenital heart disease (CHD) and how management strategies early in life may have significant implications much later in life. Patients with complex CHD should have lifelong follow-up, so our knowledge will continue to improve, and the best possible care can be provided for these patients.

Heart valve disease: investigation by cardiovascular magnetic resonance

Cardiovascular magnetic resonance (CMR) has become a valuable investigative tool in many areas of cardiac medicine. Its value in heart valve disease is less well appreciated however, particularly as echocardiography is a powerful and widely available technique in valve disease. This review highlights the added value that CMR can bring in valve disease, complementing echocardiography in many areas, but it has also become the first-line investigation in some, such as pulmonary valve disease and assessing the right ventricle. CMR has many advantages, including the ability to image in any plane, which allows full visualisation of valves and their inflow/outflow tracts, direct measurement of valve area (particularly for stenotic valves), and characterisation of the associated great vessel anatomy (e.g. the aortic root and arch in aortic valve disease). A particular strength is the ability to quantify flow, which allows accurate measurement of regurgitation, cardiac shunt volumes/ratios and differential flow volumes (e.g. left and right pulmonary arteries). Quantification of ventricular volumes and mass is vital for determining the impact of valve disease on the heart, and CMR is the 'Gold standard' for this. Limitations of the technique include partial volume effects due to image slice thickness, and a low ability to identify small, highly mobile objects (such as vegetations) due to the need to acquire images over several cardiac cycles. The review examines the advantages and disadvantages of each imaging aspect in detail, and considers how CMR can be used optimally for each valve lesion.

Surgical management of congenital (non-Ebstein) tricuspid valve regurgitation

Congenital tricuspid valve regurgitation (TR) is a relatively uncommon condition that includes a heterogeneous group of lesions with a unique management strategy. There are wide anatomic variations that lead to congenital TR in patients without Ebstein malformation. Possible etiologies may include primary valve abnormalities (eg, congenital absence of chordae) or other forms of tricuspid valve dysplasia as in congenitally unguarded tricuspid valve, and patients with pulmonary atresia and intact ventricular septum, which can be similar to Ebstein's valves or secondary regurgitation in association with other anomalies as in atrioventricular septal defects, right ventricular outflow tract obstructive lesions (pulmonary stenosis or atresia with ventricular septal defect [VSD]), tricuspid valve annular dilatation in association with right ventricular volume overload lesions as in congenital coronary arterial fistula with secondary right ventricular enlargement, and Uhl's anomaly. Iatrogenic etiologies in the congenital population include TR secondary to previous VSD closure (chordal or leaflet injury), pacemaker or internal cardiac defibrillator lead-induced TR, and traumatic TR (ruptured chordae). Presentation depends on the severity of the disease and may be apparent in infancy, childhood, or adulthood.

Congenital Heart Defects in Adults : A Field Guide for Cardiologists

Advances in cardiology and cardiac surgery allow a large proportion of patients with congenital heart defects to survive into adulthood. These patients frequently develop complications characteristic of the defect or its treatment. Consequently, adult cardiologists participating in the care of these patients need a working knowledge of the more common defects. Occasionally, patients with congenital heart defects such as atrial septal defect, Ebstein anomaly or physiologically corrected transposition of the great arteries present for the first time in adulthood. More often patients previously treated in pediatric cardiology centers have transitioned to adult congenital heart disease centers for ongoing care. Some of the more important defects in this category are tetralogy of Fallot, transposition of the great arteries, functionally single ventricle defects, and coarctation. Through this field guide, we provide an overview of the anatomy of selected defects commonly seen in an adult congenital practice using pathology specimens and clinical imaging studies. In addition, we describe the physiology, clinical presentation to the adult cardiologist, possible complications, treatment options, and outcomes.

Right ventricular regional wall curvedness and area strain in patients with repaired tetralogy of Fallot

A quantitative understanding of right ventricular (RV) remodeling in repaired tetralogy of Fallot (rTOF) is crucial for patient management. The objective of this study is to quantify the regional curvatures and area strain based on three-dimensional (3-D) reconstructions of the RV using cardiac magnetic resonance imaging (MRI). Fourteen (14) rTOF patients and nine (9) normal subjects underwent cardiac MRI scan. 3-D RV endocardial surface models were reconstructed from manually delineated contours and correspondence between end-diastole (ED) and end systole (ES) was determined. Regional curvedness (C) and surface area at ED and ES were calculated as well as the area strain. The RV shape and deformation in rTOF patients differed from normal subjects in several respects. Firstly, the curvedness at ED (mean for 13 segments, 0.030 ± 0.0076 vs. 0.029 ± 0.0065 mm(-1); P < 0.05) and ES (mean for 13 segments, 0.040 ± 0.012 vs. 0.034 ± 0.0072 mm(-1); P < 0.001) was decreased by chronic pulmonary regurgitation. Secondly, the surface area increased significantly at ED (mean for 13 segments, 982 ± 192 vs. 1,397 ± 387 mm(2); P < 0.001) and ES (mean for 13 segments, 576 ± 130 vs. 1,012 ± 302 mm(2); P < 0.001). In particular, rTOF patients had significantly larger surface area than that in normal subjects in the free wall but not for the septal wall. Thirdly, area strain was significantly decreased (mean for 13 segments, 56 ± 6 vs. 34 ± 7%; P < 0.0001) in rTOF patients. Fourthly, there were increases in surface area at ED (5,726 ± 969 vs. 6,605 ± 1,122 mm(2); P < 0.05) and ES (4,280 ± 758 vs. 5,569 ± 1,112 mm(2); P < 0.01) and decrease in area strain (29 ± 8 vs. 18 ± 8%; P < 0.001) for RV outflow tract. These findings suggest significant geometric and strain differences between rTOF and normal subjects that may help guide therapeutic treatment.

Imaging congenital heart disease in adults

Transthoracic echocardiography is the first-line modality for cardiovascular imaging in adults with congenital heart disease (ACHD). The windows of access that are possible with transthoracic echocardiography are, however, rarely adequate for all regions of interest. The choice of further imaging depends on the clinical questions that remain to be addressed. The strengths of MRI include comprehensive access and coverage, providing imaging of all parts of the right ventricle, the pulmonary arteries, pulmonary veins and aorta. Cine images and velocity maps are acquired in specifically aligned planes, with stacks of cines or dynamic contrast angiography providing more comprehensive coverage. Tissues can be characterised if necessary, and MRI provides relatively accurate measurements of biventricular function and volume flow. These parameters are important in the assessment and follow-up of adults after repairs for tetralogy of Fallot or transposition of the great arteries and after Fontan operations. The superior spatial resolution and rapid acquisition of CT are invaluable in selected situations, including the visualisation of anomalous coronary or aortopulmonary collateral arteries, the assessment of luminal patency after stenting and imaging in patients with pacemakers. Ionising radiation is, however, a concern in younger patients who may need repeated investigation. Adults with relatively complex conditions should ideally be imaged in a specialist ACHD centre, where dedicated echocardiographic and cardiovascular MRI services are a necessary facility. General radiologists should be aware of the nature and pathophysiology of congenital heart disease, and should be alert for previously undiagnosed cases presenting in adulthood, including cases of atrial septal defect, aortic coarctation, patent ductus arteriosus, double-chambered right ventricle and congenitally corrected transposition.

A statistical model for quantification and prediction of cardiac remodelling: application to tetralogy of Fallot

Cardiac remodelling plays a crucial role in heart diseases. Analyzing how the heart grows and remodels over time can provide precious insights into pathological mechanisms, eventually resulting in quantitative metrics for disease evaluation and therapy planning. This study aims to quantify the regional impacts of valve regurgitation and heart growth upon the end-diastolic right ventricle (RV) in patients with tetralogy of Fallot, a severe congenital heart defect. The ultimate goal is to determine, among clinical variables, predictors for the RV shape from which a statistical model that predicts RV remodelling is built. Our approach relies on a forward model based on currents and a diffeomorphic surface registration algorithm to estimate an unbiased template. Local effects of RV regurgitation upon the RV shape were assessed with Principal Component Analysis (PCA) and cross-sectional multivariate design. A generative 3-D model of RV growth was then estimated using partial least squares (PLS) and canonical correlation analysis (CCA). Applied on a retrospective population of 49 patients, cross-effects between growth and pathology could be identified. Qualitatively, the statistical findings were found realistic by cardiologists. 10-fold cross-validation demonstrated a promising generalization and stability of the growth model. Compared to PCA regression, PLS was more compact, more precise and provided better predictions.

Impaired mitochondrial biogenesis precedes heart failure in right ventricular hypertrophy in congenital heart disease

BACKGROUND

The outcome of the surgical repair in congenital heart disease correlates with the degree of myocardial damage. In this study, we determined whether mitochondrial DNA depletion is a sensitive marker of right ventricular (RV) damage and whether impaired mitochondrial DNA (mtDNA) replication contributes to the transition from compensated hypertrophy to failure.

METHODS AND RESULTS

RV samples obtained from 31 patients undergoing cardiac surgery were compared with 5 RV samples from nonfailing hearts (control). Patients were divided into compensated hypertrophy and failure groups, based on preoperative echocardiography, catheterization, and/or MRI data. Mitochondrial enzyme activities (citrate synthase and succinate dehydrogenase) were maintained during hypertrophy and decreased by ≈40% (P<0.05 versus control) at the stage of failure. In contrast, mtDNA content was progressively decreased in the hypertrophied RV through failure (by 28±8% and 67±11%, respectively, P<0.05 for both), whereas mtDNA-encoded gene expression was sustained by increased transcriptional activity during compensated hypertrophy but not in failure. Mitochondrial DNA depletion was attributed to reduced mtDNA replication in both hypertrophied and failing RV, and it was independent of PGC-1 downregulation but was accompanied by reduced expression of proteins constituting the mtDNA replication fork. Decreased mtDNA content in compensated hypertrophy was also associated with pathological changes of mitochondria ultrastructure.

CONCLUSIONS

Impaired mtDNA replication causes early and progressive depletion of mtDNA in the RV of the patients with congenital heart disease during the transition from hypertrophy to failure. Decreased mtDNA content probably is a sensitive marker of mitochondrial injury in this patient population.

Repeatability of cardiac-MRI-measured right ventricular size and function in congenital heart disease

BACKGROUND

The measurement error for right ventricular (RV) size and function assessed by cardiac MRI (CMRI) in congenital heart disease has not been fully characterized. As CMRI parameters are being increasingly utilized to make clinical decisions, defining error in the clinical setting is critical.

OBJECTIVE

This investigation examines the repeatability of CMRI for RV size and function.

MATERIALS AND METHODS

Forty consecutive people with congenital heart disease involving the RV were retrospectively identified. Contouring of RV volumes was performed by two expert CMRI clinicians. The coefficient of variability and repeatability coefficients were calculated. Repeatability coefficients were multiplied by the mean value for each group studied to define a threshold beyond which measurement error was unlikely to be responsible.

RESULTS

The variability for indexed RV end-diastolic volume = 3.2% and 3.3% for intra- and interobserver comparisons, respectively. The repeatability coefficients were 13.2% and 14.9% for intra- and interobserver comparisons, which yielded threshold values of 15.1 ml/m^2 and 20.2 ml/m^2, respectively. For RV ejection fraction (EF), the repeatability coefficients for intra- and interobserver comparisons were 5.0% and 6.0%, which resulted in threshold values of 2.6 EF% and 3.0 EF%.

CONCLUSION

The threshold values generated can be used during serial assessment of RV size and function.

Late pulmonary valve replacement in patients with pulmonary atresia and intact ventricular septum: a case-matched study

BACKGROUND

Pulmonary valve replacement (PVR) is a common therapy for chronic pulmonary regurgitation. However, the use of this strategy is mostly based on the studies performed on patients with tetralogy of Fallot (TOF) and not in patients with pulmonary atresia/intact ventricular septum (PA/IVS). The aim of this study is to evaluate our experience with PVR in patients with PA/IVS and compare them with a matched cohort of TOF patients.

METHODS

Between 1995 and 2009, 13 patients with PA/IVS underwent a late PVR. Matched TOF control subjects were identified for 12 of these patients. Before and after PVR echocardiographic, magnetic resonance imaging, exercise test, Holter, and electrocardiographic data were compared between groups.

RESULTS

There was no mortality in either group. The PVR improved pulmonary regurgitant fraction and right ventricular volumes in all patients. Patients with PA/IVS had more significant tricuspid regurgitation (TR [at least moderate]) by echocardiography and magnetic resonance imaging before PVR (n = 11 [85%] versus n = 1 [8%]; p = 0.003) and had more tricuspid valve repairs than TOF patients (n = 9 [69%] versus n = 1 [8%]; p = 0.004). Repair was undertaken by a combination of techniques. Although TR was improved early postoperatively, only 2 of 9 patients (22%) were free from significant TR at most recent follow-up (median 2.5 years; range, 0.1 to 10.9). No patient underwent reoperation at latest follow-up.

CONCLUSIONS

Patients with PA/IVS can undergo a late PVR with excellent results. Significant TR and repair are more commonly observed among patients with PA/IVS compared with TOF patients. Although tricuspid valve repair improves regurgitation early, TR tends to recur, suggesting the need for further refinement of current surgical techniques.

Repaired tetralogy of Fallot: the roles of cardiovascular magnetic resonance in evaluating pathophysiology and for pulmonary valve replacement decision support

Surgical management of tetralogy of Fallot (TOF) results in anatomic and functional abnormalities in the majority of patients. Although right ventricular volume load due to severe pulmonary regurgitation can be tolerated for many years, there is now evidence that the compensatory mechanisms of the right ventricular myocardium ultimately fail and that if the volume load is not eliminated or reduced by pulmonary valve replacement the dysfunction might be irreversible. Cardiovascular magnetic resonance (CMR) has evolved during the last 2 decades as the reference standard imaging modality to assess the anatomic and functional sequelae in patients with repaired TOF. This article reviews the pathophysiology of chronic right ventricular volume load after TOF repair and the risks and benefits of pulmonary valve replacement. The CMR techniques used to comprehensively evaluate the patient with repaired TOF are reviewed and the role of CMR in supporting clinical decisions regarding pulmonary valve replacement is discussed.

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.

Management of moderate functional tricuspid valve regurgitation at the time of pulmonary valve replacement: is concomitant tricuspid valve repair necessary?

Congenital heart defects with a component of pulmonary stenosis are often palliated in childhood by disrupting the pulmonary valve. Patients often undergo subsequent pulmonary valve replacement (PVR) to protect the heart from the consequences of pulmonary regurgitation. In the presence of associated moderate functional tricuspid valve (TV) regurgitation, it is unclear what factors contribute to persistent TV regurgitation following PVR. In particular, it is unknown whether PVR alone will reduce the right ventricular (RV) size and restore TV function or whether concomitant TV annuloplasty is required as well. Thirty-five patients were analyzed. Each patient underwent initial palliation of congenital pulmonary stenosis or tetralogy of Fallot, underwent subsequent PVR between 2002 and 2008, and had at least moderate TV regurgitation at the time of valve replacement. Serial echocardiograms were analyzed. Pulmonary and TV regurgitation, along with RV dilation and dysfunction, were scored (0, none; 1, mild; 2, moderate; 3, severe). RV volume and area were also calculated. Potential risk factors for persistent postoperative TV regurgitation were evaluated. One month following PVR, there was a significant reduction in pulmonary valve regurgitation (mean, 3 vs. 0.39; P < 0.0001) and TV regurgitation (mean, 2.33 vs. 1.3; P < 0.0001). There were also significant reductions in RV dilation, volume, and area. There were no significant further improvements in any of the parameters at 1 and 3 years. There was no difference in the degree of TV regurgitation postoperatively between those patients who underwent PVR alone and those who underwent concomitant tricuspid annuloplasty (mean, 1.29 vs. 1.31; P = 0.81). We conclude that following PVR, improvement in TV regurgitation and RV size occurs primarily in the first postoperative month. TV function improved to a similar degree with or without annuloplasty.

Pulmonary valve replacement with mechanical prosthesis: long-term results in 4 patients

Pulmonary valve replacement is rarely performed and is usually done with biological prostheses or grafts. The use of mechanical prostheses is still a debated issue. We analyzed the outcome of 4 patients at 11 years after pulmonary valve replacement with a mechanical prosthesis. During follow-up, all patients remained asymptomatic, with no arrhythmias and good anticoagulation. An echocardiogram showed preserved ventricular contraction and normal function of the prostheses, with low pressure gradients. No infective endocarditis occurred. Mechanical prostheses appear to be a good choice for pulmonary valve replacement. Surgical and clinical results were satisfactory with no complications, acceptable pressure gradients, and good ventricular function after more than 10 years. Lifelong anticoagulation is mandatory, but this is usually well tolerated.

Right ventricular failure secondary to chronic overload in congenital heart disease: an experimental model for therapeutic innovation

OBJECTIVE

Mortality and morbidity related to right ventricular failure remain a problem for the long-term outcome of congenital heart diseases. Therapeutic innovation requires establishing an animal model reproducing right ventricular dysfunction secondary to chronic pressure-volume overload.

METHODS

Right ventricular tract enlargement by transvalvular patch and pulmonary artery banding were created in 2-month-old piglets (n = 6) to mimic repaired tetralogy of Fallot. Age-matched piglets were used as controls (n = 5). Right ventricular function was evaluated at baseline and 3 and 4 months of follow-up by hemodynamic parameters and electrocardiography. Right ventricular tissue remodeling was characterized using cellular electrophysiologic and histologic analyses.

RESULTS

Four months after surgery, right ventricular peak pressure increased to 75% of systemic pressure and pulmonary regurgitation significantly progressed, end-systolic and end-diastolic volumes significantly increased, and efficient ejection fraction significantly decreased compared with controls. At 3 months, the slope of the end-systolic pressure-volume relationship was significantly elevated compared with baseline and controls; a significant rightward shift of the slope, returning to the baseline value, was observed at 4 months, whereas stroke work progressed at each step and was significantly higher than in controls. Four months after surgery, QRS duration was significantly prolonged as action potential duration. Significant fibrosis and myocyte hypertrophy without myolysis and inflammation were observed in the operated group at 4 months.

CONCLUSION

Various aspects of early right ventricular remodeling were analyzed in this model. This model reproduced evolving right ventricular alterations secondary to chronic volumetric and barometric overload, as observed in repaired tetralogy of Fallot with usual sequelae, and can be used for therapeutic innovation.

Recommendations for cardiovascular magnetic resonance in adults with congenital heart disease from the respective working groups of the European Society of Cardiology

This paper aims to provide information and explanations regarding the clinically relevant options, strengths, and limitations of cardiovascular magnetic resonance (CMR) in relation to adults with congenital heart disease (CHD). Cardiovascular magnetic resonance can provide assessments of anatomical connections, biventricular function, myocardial viability, measurements of flow, angiography, and more, without ionizing radiation. It should be regarded as a necessary facility in a centre specializing in the care of adults with CHD. Also, those using CMR to investigate acquired heart disease should be able to recognize and evaluate previously unsuspected CHD such as septal defects, anomalously connected pulmonary veins, or double-chambered right ventricle. To realize its full potential and to avoid pitfalls, however, CMR of CHD requires training and experience. Appropriate pathophysiological understanding is needed to evaluate cardiovascular function after surgery for tetralogy of Fallot, transposition of the great arteries, and after Fontan operations. For these and other complex CHD, CMR should be undertaken by specialists committed to long-term collaboration with the clinicians and surgeons managing the patients. We provide a table of CMR acquisition protocols in relation to CHD categories as a guide towards appropriate use of this uniquely versatile imaging modality.

Conotruncal cardiac defects: a clinical imaging perspective

Conotruncal cardiac defects make up a significant portion of congenital heart disease. For proper diagnosis and subsequent care of patients with these defects, different and sometimes multiple imaging modalities are needed at various stages of care. This article reviews the characteristics of some of the most common conotruncal defects and the imaging options available along with the advantages and disadvantages of each. Intricate knowledge of the capabilities of each modality will aid the practitioner in making optimal clinical decisions.