Role of ischemia and infarction in late right ventricular dysfunction after atrial repair of transposition of the great arteries

Ventricular Arrhythmias in Adults With Congenital Heart Disease, Part II: JACC State-of-the-Art Review

There are marked variations in the incidence of sudden cardiac death (SCD) and in the substrates for ventricular arrhythmias (VAs) across the gamut of congenital heart defects. In this 2-part review, patients with higher-risk forms of congenital heart disease (CHD) were conceptually categorized into those with discrete anatomic isthmuses for macro-reentrant ventricular tachycardia (VT) (Group A) and those with more diffuse or less well-defined substrates (Group B) that include patchy or extensive myocardial fibrosis. The latter category encompasses CHD lesions such as Ebstein anomaly, transposition of the great arteries with a systemic right ventricle (RV), and congenital aortic stenosis. For Group B patients, polymorphic VT and ventricular fibrillation account for a higher proportion of VA. The prognostic value of programmed ventricular stimulation is less well established, and catheter ablation plays a less prominent role. As cardiomyopathies evolve over time, pathophysiological mechanisms for VA among Groups A and B become increasingly blurred.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

The association between myocardial ischemia and myocardial dysfunction in adult patients with systemic right ventricle - A single centre multimodality study

BACKGROUND

The exact interaction of factors leading to myocardial dysfunction and fibrosis of the systemic right ventricle (SRV) is not completely understood. Myocardial ischemia and injury associated with a supply-demand mismatch of the pressure overloaded SRV are thought to play an important role, however studies confirming this are lacking.

METHODS

Adult SRV patients were included in this single centre cohort study. All patients underwent a comprehensive diagnostic and imaging workup. A two-day stress-rest SPECT was performed to assess myocardial perfusion. SRV ischemia was defined as decreased segmental tracer uptake during exercise with significant improvement at rest. Contrast enhanced cardiac magnetic resonance imaging (CMR) was also performed in a subgroup of patients without contraindication, to assess focal myocardial fibrosis. Differences between patients with and without SRV ischemia were assessed.

RESULTS

Twenty-three SRV patients (15 with transposition of the great arteries after atrial switch procedure and 8 with congenitally corrected transposition of the great arteries; 5 (22%) females; mean age 38 ± 11 years) were included. Seven (30%) patients had SRV ischemia on SPECT. Late gadolinium enhancement on CMR was more common in patients with SRV ischemia (p = 0.002). However, there was no association between SRV ischemia and different echocardiographic or CMR parameters of SRV systolic function, laboratory markers (high-sensitivity troponin I and NT-proBNP) and exercise capacity.

CONCLUSIONS

Our multimodality study showed that SRV ischemia in adult SRV patients was associated with more focal myocardial fibrosis, but not with functional or imaging markers of SRV function.

Tachyarrhythmias in Congenital Heart Diseases: From Ion Channels to Catheter Ablation

Major advances in pediatric cardiology in recent decades, especially surgical techniques, have resulted in an increasing number of patients with congenital heart disease (CHD) surviving to adulthood. This has generated new challenges, particularly with regards to the late onset of complex arrhythmias. Abnormal anatomy, surgical scarring, chronic hypoxemia, hemodynamic compromise, neuro-hormonal abnormalities, and genetic factors can all contribute to creating a unique substrate for arrhythmia development. This review attempts to synthesize the current state of knowledge spanning the spectrum from underlying mechanisms of arrhythmias in patients with congenital heart disease to current ablative strategies. We discuss existing knowledge gaps and highlight important areas for future research.

Systolic and diastolic functional reserve of the subpulmonary and systemic right ventricles as assessed by pharmacologic and exercise stress: A systematic review

We performed a systematic review of the literature on the assessment of subpulmonary and systemic right ventricular (RV) functional reserve during pharmacological and exercise stress in congenital heart patients and patients with pulmonary arterial hypertension (PAH). Literature search was conducted using PubMed, EMBASE, and MEDLINE from their inception up to August 2020. Of 913 records identified, 56 studies with a total of 1730 patients were included. Of the 56 studies, 23 assessed subpulmonary RV functional reserve in repaired tetralogy of Fallot patients, 19 assessed systemic RV reserve in patients with transposition of the great arteries (TGA) after atrial switch and those with congenitally corrected TGA, and 14 assessed subpulmonary RV research in patients with PAH. Pharmacological and exercise stress was used, respectively, in 22 and 34 studies. The main findings were (1) impairment of RV systolic and diastolic functional reserve, (2) associations between impaired functional reserve and worse baseline functional parameters, and (3) prognostic implications of RV systolic functional reserve on clinical outcomes in patients with volume and/or pressure-loaded subpulmonary and systemic right ventricles. Further studies are required to establish the incremental value of incorporating stress studies of RV systolic and diastolic function in the clinical management algorithm of congenital heart patients and patients with PAH.

Heart rate response during exercise predicts exercise tolerance in adults with transposition of the great arteries and atrial switch operation

BACKGROUND

To assess the relationship between heart rate response and exercise tolerance in adults with systemic right ventricle (sRV) after atrial switch repair for Transposition of the Great Artery (TGA) in addition to other physiological parameters.

METHODS

All patients with a sRV after atrial switch repair for TGA followed in our institution between June 2015 and April 2018 who underwent cardiopulmonary exercise testing (CPET) were analyzed. Cardiac imaging performed within a six-month time period of the CPET were also collected. Chronotropic incompetence was defined as the inability to achieve 80% of age-predicted maximal heart rate reserve (HRR) and <62% on a beta-blocker regimen. Patient characteristics were assessed according to tertiles of the percentage of predicted pVO2 (%ppVO2).

RESULTS

We studied 70 patients (mean of age 32.4 ± 7.6 years old, 51 males). Mean peak oxygen uptake was 21.5 ± 5.8 mL/kg/min, corresponding to a %ppVO2 of 57 ± 14.1% while mean VE/VCO2 slope was 37.1 ± 8.2. There was a trend toward more exaggerated hyperventilation in patient with lower pVO2. Mean age-adjusted HRR was 68.5 ± 19%. Chronotropic incompetence was observed in 65.7% and was correlated with %ppVO2 (r = 0.482; p < 0.001) as physical training evaluated with Ventilatory Anaerobic threshold (r = 0.571; p < 0.001), while no difference was found based on respiratory parameters. No echocardiographic or Magnetic Resonance Imaging parameters assessing sRV systolic function at rest were correlated with %ppVO2.

CONCLUSIONS

Exercise limitation is related to the inability to increase cardiac output during exercise and is notably due to the degree of chronotropic incompetence.

Arrhythmias in Adults With Congenital Heart Disease: What the Practicing Cardiologist Needs to Know

The expanding population of adults with congenital heart disease (CHD) combined with the pervasiveness of arrhythmias has resulted in the rapid growth of a dedicated sector of cardiology at the intersection between 2 subspecialties: electrophysiology and adult CHD. Herein, practical considerations are offered regarding urgent referral for catheter ablation of atrial arrhythmias, anticoagulation, and primary prevention implantable cardioverter-defibrillators (ICDs). Patients with Ebstein anomaly and ventricular pre-excitation should be referred promptly due to the high prevalence of multiple accessory pathways and increased incidence of atrial tachyarrhythmias, which may be poorly tolerated. In patients with transposition of the great arteries and atrial switch surgery, atrial arrhythmias should be managed without delay because they could provoke ventricular arrhythmias and sudden death. Other settings in which atrial arrhythmias can be poorly tolerated include single ventricle physiology and Eisenmenger syndrome. Long-term anticoagulation is generally indicated in patients with sustained intra-atrial reentrant tachycardia or atrial fibrillation and a mechanical valve, moderate or severe systemic atrioventricular valve stenosis, traditional risk factors for stroke, and/or moderate or complex CHD. The only class I indication for a primary prevention ICD is a systemic left ventricular ejection fraction ≤ 35%, with biventricular physiology, and New York Heart Association class II or III symptoms. ICD therapy is reasonable in selected adults with tetralogy of Fallot and multiple risk factors for sudden death identified by observational studies. Indications for ICDs in patients with systemic right ventricles and univentricular hearts are less well established, underscoring the need for future research to inform risk stratification.

Sudden death in transposition of the great arteries with atrial switch surgery: Autopsy evidence of acute myocardial ischemia despite normal coronary arteries

BACKGROUND

Sudden death is the leading cause of mortality in patients with transposition of the great arteries (TGA) and atrial switch surgery. Understanding underlying mechanisms could contribute to identifying high-risk patients and preventing such catastrophic deaths.

METHODS

A total of 144 adults (≥18 years) with TGA and atrial switch surgery were followed at our adult congenital center since 1989. Four patients were excluded: two with double-outlet right ventricles and two with subsequent arterial switch surgery in childhood.

RESULTS

Of the remaining 140 patients, age 37.6 ± 7.8 years, 37.1% female, 8 (6%) had a cardiac arrest of presumed arrhythmic etiology of whom 3 were resuscitated. The arrests occurred in 3 women and 5 men at age 30.5 ± 8.6 (range 22 to 50) years. None had established coronary artery disease, sustained ventricular arrhythmias, or syncope. Four (50%) had atrial arrhythmias and 6 (75%) had at least moderate systemic right ventricular dysfunction. For 5 patients in whom circumstances surrounding the arrests were documented, 3 occurred on exertion, 1 after consuming recreational methamphetamine, and 1 in the context of an atrial tachyarrhythmia. Autopsies were performed in 2 of 5 patients. Both revealed acute massive myocardial infarction of the hypertrophied systemic right ventricle with normal coronary arteries and chronic subendocardial ischemic lesions.

CONCLUSION

This is the first report to provide histopathological evidence in support of a myocardial ischemia hypothesis as a cause of sudden death in this patient population, despite the absence of coronary atherosclerosis.

Dysfunction of the systemic right ventricle after atrial switch: physiological implications of altered septal geometry and load

Atrial switch operation in patients with transposition of the great arteries (TGA) leads to leftward shift and changes the geometry of the interventricular septum. By including the implications of regional work and septal curvature, this study investigates if changes in septal function and geometry contribute to reduced function of the systemic right ventricle (RV) in adult TGA patients. Regional myocardial work estimation has been possible by applying a recently developed method for noninvasive work calculation based on echocardiography. In 14 TGA patients (32 ± 6 yr, means ± SD) and 14 healthy controls, systemic ventricular systolic strains were measured by speckle tracking echocardiography and regional work was calculated by pressure-strain analysis. In TGA patients, septal longitudinal strain was reduced to −14 ± 2 vs. −20 ± 2% in controls ( P < 0.01) and septal work was reduced from 2,046 ± 318 to 1,146 ± 260 mmHg·% ( P < 0.01). Septal circumferential strain measured in a subgroup of patients was reduced to −11 ± 3 vs. −27 ± 3% in controls ( P < 0.01), and a reduction of septal work (540 ± 273 vs. 2,663 ± 459 mmHg·%) was seen ( P < 0.01). These reductions were in part attributed to elevated afterload due to increased radius of curvature of the leftward shifted septum. To conclude, in this mechanistic study we demonstrate that septal dysfunction contributes to failure of the systemic RV after atrial switch in TGA patients. This is potentially a long-term response to increased afterload due to a flatter septum and suggests that medical therapy that counteracts septal flattening may improve function of the systemic RV.

NEW & NOTEWORTHY We have demonstrated that transposition of the great arteries patients with systemic right ventricles (RVs) have reduced function of the interventricular septum (IVS). Since the IVS is constructed to eject into the systemic circulation, it may seem unexpected that it does not maintain function when being part of the systemic RV. By applying the principles of regional work, wall tension, and geometry, we have identified unfavorable working conditions for the IVS when the RV adapts to systemic pressures.

Limited Ventricular Preload is the Main Reason for Reduced Stress Reserve After Atrial Baffle Repair

The atrial baffle repair (ABR) significantly improved the fate of patients with transposition of the great arteries (TGA). However, these patients show impaired exercise tolerance and some present severe decline of systemic ventricular function. Intrinsic myocardial weakness, low heart rate response to exercise and diastolic filling impairment are discussed to be causative. Forty-nine long-term survivors with TGA (median age 23.7 year) after ABR were catheterized with measured oxygen consumption in four conditions (baseline, volume, atrial pacing, dobutamine) and the results were compared to 10 normal controls. Median cardiac output was significantly lower in the ABR group (2.2 vs. 2.6 l/min/m²; p = 0.015), and systemic resistance was significantly elevated (28.9 vs. 22.2 U m²; p = 0.04) in comparison with normals. While stroke volume rose by 27% in the control group, it dropped by 7% in patients after ABR at atrial pacing (80/min). Stroke volume increase after dobutamine was significantly lower after ABR in comparison with normal controls (34 vs. 106%; p = 0.001). Higher NYHA class (p = 0.043), degree of tricuspid regurgitation (p = 0.009) and ventricular function (p = 0.028) were associated with lower stroke volume increase. Limited exercise capability of patients after ABR for TGA is primarily due to limited diastolic filling of the ventricles due to stiff non-compliant atrial pathways. Elevated systemic resistance may lead to severe myocardial hypertrophy with possible ischemia and contribute to the multifactorial decline of ventricular function in some patients.

Cardiovascular response to exercise training in the systemic right ventricle of adults with transposition of the great arteries

KEY POINTS

Patients with transposition of the great arteries (TGA) and systemic right ventricles have premature congestive heart failure; there is also a growing concern that athletes who perform extraordinary endurance exercise may injure the right ventricle. Therefore we felt it essential to determine whether exercise training might injure a systemic right ventricle which is loaded with every heartbeat. Previous studies have shown that short term exercise training is feasible in TGA patients, but its effect on ventricular function is unclear. We demonstrate that systemic right ventricular function is preserved (and may be improved) in TGA patients with exercise training programmes that are typical of recreational and sports participation, with no evidence of injury on biomarker assessment. Stroke volume reserve during exercise correlates with exercise training response in our TGA patients, identifying this as a marker of a systemic right ventricle (SRV) that may most tolerate (and possibly even be improved by) exercise training.

ABSTRACT

We aimed to assess the haemodynamic effects of exercise training in transposition of the great arteries (TGA) patients with systemic right ventricles (SRVs). TGA patients have limited exercise tolerance and early mortality due to systemic (right) ventricular failure. Whether exercise training enhances or injures the SRV is unclear. Fourteen asymptomatic patients (34 ± 10 years) with TGA and SRV were enrolled in a 12 week exercise training programme (moderate and high-intensity workouts). Controls were matched on age, gender, BMI and physical activity. Exercise testing pre- and post- training included: (a) submaximal and peak; (b) prolonged (60 min) submaximal endurance and (c) high-intensity intervals. Oxygen uptake (V̇O2; Douglas bag technique), cardiac output (Q̇c, foreign-gas rebreathing), ventricular function (echocardiography and cardiac MRI) and serum biomarkers were assessed. TGA patients had lower peak V̇O2, Q̇c, and stroke volume (SV), a blunted Q̇c/V̇O2 slope, and diminished SV response to exercise (SV increase from rest: TGA = 15.2%, controls = 68.9%, P < 0.001) compared with controls. After training, TGA patients increased peak V̇O2 by 6 ± 8.5%, similar to controls (interaction P = 0.24). The magnitude of SV reserve on initial testing correlated with Q̇c training response (r = 0.58, P = 0.047), though overall, no change in peak Q̇c was observed. High-sensitivity troponin T (hs-TnT) and N-terminal prohormone of brain naturetic peptide (NT pro-BNP) were low and did not change with acute exercise or after training. Our data show that TGA patients with SRVs in this study safely participated in exercise training and improved peak V̇O2. Neither prolonged submaximal exercise, nor high-intensity intervals, nor short-term exercise training seem to injure the systemic right ventricle.

Quantification of systemic right ventricle by echocardiography

Improvements in cardiac imaging have recently focused a great interest on the right ventricle (RV). In patients with congenital heart disease, the right ventricle (RV) may support the systemic circulation (systemic RV). There are 2 different anatomic conditions providing such physiology: the congenitally corrected transposition of the great arteries (ccTGA) and the TGA surgically corrected by atrial switch. During the last decades, evidence is accumulating that progressive systemic RV failure develops leading to considerable morbidity and mortality. Various imaging modalities have been used to evaluate the systemic RV, but echocardiography is still predominantly used in clinical practice, allowing an anatomic and functional approach of the systemic RV function and the potential associated anomalies. The goal of this review is to offer a clinical perspective of the non-invasive evaluation of the systemic RV by echocardiography.

Clinical applications of radionuclide imaging in the evaluation and management of patients with congenital heart disease

Non-invasive testing of children with congenital heart disease (CHD) began in the 1950s with the introduction of radionuclide studies to assess shunt fractions, pulmonary blood flow, and ventricular contractile function. Echocardiography and cardiac magnetic resonance imaging have since replaced radionuclide imaging in many of these roles. Concurrently, percutaneous and surgical repairs of complex CHD evolved, creating new roles for radionuclide imaging. In this paper on applications of radionuclide imaging in CHD, we review the multiple mechanisms for myocardial ischemia in CHD. We critically compare optimal radionuclide imaging techniques to other imaging modalities for assessing ischemia in CHD. We present the current role of nuclear imaging for assessing viability and pulmonary blood flow. We highlight the value added by advances in dedicated cardiac SPECT scanners, novel reconstruction software, and cardiac PET in performing low-dose radionuclide imaging in CHD. Finally, we discuss the emerging clinical indications for radionuclide imaging in CHD including coronary flow reserve assessment and evaluation of cardiovascular prosthesis and device infections.

Implantable cardiac defibrillator among adults with transposition of the great arteries and atrial switch operation: case series and review of literature

BACKGROUND

The experience with the implantable cardiac defibrillator (ICD) in patients with transposition of the great arteries (TGA) and history of atrial switch surgery remains limited.

METHODS

Retrospective evaluation aiming to assess characteristics and outcomes of consecutive TGA patients with history of atrial switch surgery implanted with an ICD between January 2005 and June 2012 in four French centers.

RESULTS

Of the 12 patients (median 34 years [28, 40]; 67% male), 4 patients (33%) were implanted for secondary prevention after symptomatic documented sustained ventricular tachycardia or sudden cardiac arrest. ICDs were implanted for primary prevention in 8 patients (67%), including cardiac resynchronization in 3 patients; severe systemic ventricle dysfunction was present in all cases (median ejection fraction 27% [20, 40]). Overall, one patient died during the ICD implantation secondary to refractory cardiac arrest after defibrillation testing. Over a median follow-up of 19 months [10, 106], 6 patients out of 11 (54%) experienced worsening of congestive heart failure, including 5 who were eventually transplanted. Overall, 3 patients (27%) experienced significant ICD-related complications, whereas only one patient (primary prevention indication) developed appropriate ICD therapy (successful anti-tachycardia pacing without shock). Half of the patients presented with at least one episode of sustained (≥ 5 min) atrial arrhythmia during follow-up.

CONCLUSIONS

Our findings underline the key role of progressive heart failure in dictating outcomes among TGA patients with prior atrial switch repair. Our results also underline the need of better risk-stratification for sudden cardiac death in those patients.

The right ventricle in pulmonary arterial hypertension: disorders of metabolism, angiogenesis and adrenergic signaling in right ventricular failure

The right ventricle (RV) is the major determinant of functional state and prognosis in pulmonary arterial hypertension. RV hypertrophy (RVH) triggered by pressure overload is initially compensatory but often leads to RV failure. Despite similar RV afterload and mass some patients develop adaptive RVH (concentric with retained RV function), while others develop maladaptive RVH, characterized by dilatation, fibrosis, and RV failure. The differentiation of adaptive versus maladaptive RVH is imprecise, but adaptive RVH is associated with better functional capacity and survival. At the molecular level, maladaptive RVH displays greater impairment of angiogenesis, adrenergic signaling, and metabolism than adaptive RVH, and these derangements often involve the left ventricle. Clinically, maladaptive RVH is characterized by increased N-terminal pro-brain natriuretic peptide levels, troponin release, elevated catecholamine levels, RV dilatation, and late gadolinium enhancement on MRI, increased (18)fluorodeoxyglucose uptake on positron emission tomography, and QTc prolongation on the ECG. In maladaptive RVH there is reduced inotrope responsiveness because of G-protein receptor kinase-mediated downregulation, desensitization, and uncoupling of β-adrenoreceptors. RV ischemia may result from capillary rarefaction or decreased right coronary artery perfusion pressure. Maladaptive RVH shares metabolic abnormalities with cancer including aerobic glycolysis (resulting from a forkhead box protein O1-mediated transcriptional upregulation of pyruvate dehydrogenase kinase), and glutaminolysis (reflecting ischemia-induced cMyc activation). Augmentation of glucose oxidation is beneficial in experimental RVH and can be achieved by inhibition of pyruvate dehydrogenase kinase, fatty acid oxidation, or glutaminolysis. Therapeutic targets in RV failure include chamber-specific abnormalities of metabolism, angiogenesis, adrenergic signaling, and phosphodiesterase-5 expression. The ability to restore RV function in experimental models challenges the dogma that RV failure is irreversible without regression of pulmonary vascular disease.

Circulating microRNA expression profile and systemic right ventricular function in adults after atrial switch operation for complete transposition of the great arteries

Background

Data on the use of circulating microRNAs (miRNAs) as biomarkers of cardiovascular diseases are emerging. Little, however, is known on the expression profile of circulating of microRNAs in congenital heart malformations with a systemic right ventricle that is prone to functional impairment. We aimed to test the hypothesis that circulating miRNA profile is altered in patients late after atrial switch operation for complete transposition of the great arteries (TGA) and further explored possible relationships between alteration of circulating miRNAs and systemic ventricular contractility.

Methods

Circulating miRNA expression profiling of serum samples from 5 patients and 5 healthy controls was performed. The results were validated in 26 patients and 20 controls using real-time quantitative reverse-transcription polymerase chain reaction for candidate miRNAs with fold changes >3 by expression profiling. Systemic ventricular myocardial acceleration during isovolumic contraction (IVA) was determined by colour tissue Doppler echocardiography.

Results

Compared with controls, patients had significantly lower systemic ventricular IVA (p = 0.002). Of the 23 upregulated miRNAs identified by profiling, 11 were validated to be increased in patients compared with controls: miR-16, miR-106a, miR-144*, miR-18a, miR-25, miR-451, miR-486-3p, miR-486-5p, miR-505*, let-7e and miR-93. Among the validated 11 miRNAs, miR-18a (r = −0.45, p = 0.002) and miR-486-5p (r = −0.35, p = 0.018) correlated negatively with systemic ventricular IVA for the whole cohort.

Conclusions

A distinct serum miRNA expression signature exists in adults with complete TGA after atrial switch operation, with serum miR-18a and miR-486-5p being associated with systemic ventricular contractility.

Late primary arterial switch for transposition of the great arteries with intact ventricular septum in an african population

The arterial switch operation (ASO) is the optimal management of transposition of the great arteries with intact ventricular septum (TGA-IVS) within the first 3 weeks of life; beyond this age optimal treatment is debatable. The authors adopted a strategy of primary ASO for TGA-IVS in the first 10 weeks of life regardless of left ventricular (LV) status. This report reviews the early outcomes with this management approach. Between August 2006 and December 2009, 22 patients with TGA-IVS underwent the primary ASO. Sixteen of them were less than 21 days old (early switch group) and 6 were between 31 and 66 days old (late switch group). A review of their hospital records was performed to determine outcomes in the 2 groups. Operative variables and postoperative outcomes were recorded. There was 1 hospital death in the early switch group (6.3%) but none in the late group (0%). Temporary mechanical circulatory support was required in 1 patient (6.3%) in the early switch group and in 2 of the 6 (33.3%) in the late switch group. One late death of undetermined cause occurred in the late switch group 8 weeks after discharge. No significant difference could be demonstrated between the 2 groups in terms of operative variables and the measured postoperative outcomes. It is concluded that the age limit for the primary ASO can be extended to at least 10 weeks; temporary mechanical circulatory support may be required as a rescue.

Late arrhythmias after surgery for transposition of the great arteries

The evolution of surgical techniques for transposition of the great arteries (TGA) provides a moving target for the assessment of late arrhythmias. Imposed on varying anatomical substrates are progressive surgical interventions, each with its own set of sequelae. Analysis of the risk of arrhythmia development requires division into which arrhythmia is present, for which form of transposition, undergoing what type of surgery, and in which surgical era. For purposes of this review, available data on d-TGA undergoing Senning repairs, Mustard repairs, and arterial switch repairs and congenitally corrected TGA undergoing double switch repairs are reviewed.

Myocardial perfusion abnormalities in patients occurring more than 1 year after successful univentricular (Fontan surgery) and biventricular repair (complete repair of tetralogy of Fallot)

The outcome of children born with cyanotic congenital heart disease has markedly improved over the years. Follow up is recommended for most post-operated cases as complications may occur over long term. One of the complications is the development of ventricular dysfunction, often seen after a successful Fontan surgery (or one of its modifications) for single ventricle. The aim of this study was to determine the prevalence of myocardial perfusion abnormalities in the ventricular myocardium of asymptomatic patients, older than 8 years of age, who had earlier undergone either a univentricular palliation (modified Fontan procedure) or a biventricular repair for tetralogy of Fallot, more than a year ago. All eligible patients underwent screening electrocardiogram (to rule out rhythm disturbance) and echocardiography. Patients with ventricular ejection fraction of more than 50 % by echocardiography were included. Enrolled patients were subjected to gated stress-rest myocardial perfusion imaging using Technitium-99m tetrofosmin single photon emission-computerized tomography (SPECT). Ventricular ejection fraction was also calculated from gated rest study. For the Fontan group, we also analyzed data to see if the morphology of the systemic ventricle would make a difference as far as myocardial perfusion was concerned. Twenty-six patients were enrolled (11 had undergone Fontan surgery and 15 had complete repair of tetralogy of Fallot). Seven of 11 patients in the Fontan group had myocardial perfusion defects (63.6 %) as against none in the repaired tetralogy of Fallot group (p < 0.001). The ejection fraction was within normal range in both the groups; it was statistically higher in the post tetralogy of Fallot repair group (p < 0.04). There were two subgroups in the post Fontan group depending on the morphology of systemic ventricle-left (4 patients) and non-left (7 patients). Higher number and larger size of perfusion defects were present in the non-left ventricular systemic ventricle morphology as compared with left ventricular morphology, but this difference did not reach statistical significance. Myocardial perfusion defects are common in patients who have undergone univentricular repair more than one year ago in contrast to patients who had a biventricular repair for tetralogy of Fallot. In the Fontan group, the morphology of the systemic ventricle was not predictive of prevalence of perfusion defect.

Right ventricular failure in congenital heart disease

Despite developments in surgical techniques and other interventions, right ventricular (RV) failure remains an important clinical problem in several congenital heart diseases (CHD). RV function is one of the most important predictors of mortality and morbidity in patients with CHD. RV failure is a progressive disorder that begins with myocardial injury or stress, neurohormonal activation, cytokine activation, altered gene expression, and ventricular remodeling. Pressure-overload RV failure caused by RV outflow tract obstruction after total correction of tetralogy of Fallot, pulmonary stenosis, atrial switch operation for transposition of the great arteries, congenitally corrected transposition of the great arteries, and systemic RV failure after the Fontan operation. Volume-overload RV failure may be caused by atrial septal defect, pulmonary regurgitation, or tricuspid regurgitation. Although the measurement of RV function is difficult because of many reasons, the right ventricle can be evaluated using both imaging and functional modalities. In clinical practice, echocardiography is the primary mode for the evaluation of RV structure and function. Cardiac magnetic resonance imaging is increasingly used for evaluating RV structure and function. A comprehensive evaluation of RV function may lead to early and optimal management of RV failure in patients with CHD.

Usefulness of myocardial perfusion imaging with exercise testing in children

Myocardial perfusion imaging (MPI) provides additional clinical information on children with cardiac disease but will not benefit children with chest pain and normal cardiac studies. This study reviewed all technetium-99 m ((99m)Tc) sestamibi stress MPI studies between 2004 and 2010 performed in association with graded exercise testing (86% with bicycle ergometer, 14% with treadmill). A positive test was defined as a perfusion defect or abnormal ventricular function response. Clinical records were reviewed, including follow-up assessment to determine accuracy of MPI interpretation. False-positive and false-negative rates were recorded. A total of 197 patients (mean age, 13.4 ± 3.6 years, 70% male) underwent 218 MPI studies. Group A had 42 patients (43 studies) with isolated chest pain and normal studies. Of the 43 studies, 39 had negative results, and 4 had false-positive results. Group B had 155 patients (175 studies) with known or suspected cardiac disease, and 39 tests (33 patients) had positive results. Whereas 32 studies were considered true-positive, 7 were false-positive. There was one false-negative test. According to the findings, (99m)Tc sestamibi MPI studies are clinically useful but not perfect tests in the setting of known or suspected cardiac disease based on clinical evaluation, electrocardiography (ECG), or echocardiography. Children who had isolated chest pain with a normal ECG and echocardiogram often have false-positive studies.

Echocardiographic knowledge-based reconstruction for quantification of the systemic right ventricle in young adults with repaired D-transposition of great arteries

The systemic right ventricle (RV) in congenital heart disease is susceptible to progressive dilation and dysfunction. A 2-dimensional echocardiographic means for serial monitoring of the RV would be of great value in this clinical setting. We used 2-dimensional echocardiography with knowledge-based reconstruction (2DE-KBR) for evaluation of systemic RV. Patients with d-transposition of great arteries repaired with an atrial switch and without implanted pacemakers were prospectively recruited for same-day 2DE-KBR and cardiac magnetic resonance (CMR) imaging. RV images were acquired in various 2-dimensional imaging planes using a 3-dimensional space-localizing device attached to the imaging transducer and 3-dimensional reconstruction was performed. RV end-diastolic volume, end-systolic volume, and ejection fraction (EF) were calculated and compared to volumetric CMR analysis. Fifteen patients (7 women, 8 men, 24 ± 7 years old, weight 67 ± 12 kg) were studied. There was good agreement of 2DE-KBR and CMR measurements. Mean RV end-diastolic volume was 221 ± 39 ml with 2DE-KBR and 231 ± 35 ml with CMR (r = 0.80); mean end-systolic volume was 129 ± 35 ml with KBR and 132 ± 30 ml with CMR (r = 0.82), and EF was 42 ± 10% with KBR and 43 ± 7% with CMR (r = 0.86). For 2DE-KBR mean interobserver variabilities were 4.6%, 2.6%, and 4.3%; intraobserver variabilities were 3.2%, 3.1%, and 2.3%, respectively, for end-diastolic volume, end-systolic volume, and EF. In conclusion, this study demonstrates the clinical feasibility of quantifying systemic RV volumes and function using 2DE-KBR in adolescents and young adults with repaired d-transposition of great arteries and good agreement of measurements with CMR.

Right ventricle myocardial perfusion scintigraphy: feasibility and expected values in children

Stress myocardial perfusion scintigraphy imaging (SMPSI) has important applications for evaluating coronary disease and ventricular function. Studies consistently focus on the left ventricle (LV), with no normal right ventricle (RV) data available. This study sought to evaluate the feasibility of RV perfusion with technetium (Tc-99m) sestamibi using a low radiotracer dose for children free of coronary artery (CA) anomalies and to determine its normal pattern. Patients with a history of Kawasaki disease who showed no coronary complications on selective angiography or no LV perfusion defects on SMPSI were studied at rest and during an exercise challenge. The RV uptake counts were compared with those for different segments of the LV, and multiple ratios of the uptakes between RV and LV segments were calculated. The study subjects were 23 children (age, 11.1 ± 3.3 years) imaged with 0.12 ± 0.03 mCi/kg at rest and 0.31 ± 0.06 mCi/kg during stress. The RV to LV uptake proportion was approximately 6%. Exercise-related uptake increased threefold in both the RV and the LV. The findings showed RV myocardial scintigraphy to be feasible with reproducible ratios. Potential clinical applications include acquired and congenital CA anomalies such as Kawasaki disease, right CA ostium stenosis after a switch operation, and anomalous origin of the right CA.

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.

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.

The role of cardiovascular magnetic resonance in pediatric congenital heart disease

Cardiovascular magnetic resonance (CMR) has expanded its role in the diagnosis and management of congenital heart disease (CHD) and acquired heart disease in pediatric patients. Ongoing technological advancements in both data acquisition and data presentation have enabled CMR to be integrated into clinical practice with increasing understanding of the advantages and limitations of the technique by pediatric cardiologists and congenital heart surgeons. Importantly, the combination of exquisite 3D anatomy with physiological data enables CMR to provide a unique perspective for the management of many patients with CHD. Imaging small children with CHD is challenging, and in this article we will review the technical adjustments, imaging protocols and application of CMR in the pediatric population.

Pregnancy in women with congenital heart disease: the impact of a systemic right ventricle

OBJECTIVE

Individuals with a systemic right ventricle develop cardiac complications earlier in life. Limited data exists regarding the effect of a maternal systemic right ventricle on cardiac events during pregnancy. We sought to assess the effect of a systemic right ventricle on cardiac events and pregnancy outcomes.

DESIGN

The study was designed as a retrospective cohort study of pregnant women with maternal congenital heart disease.

SETTING

The study was set in a university, academic tertiary care referral center.

PATIENTS

Study subjects were identified by International Statistical Classification of Diseases and Related Health Problems-9 codes. Women with mitral valve prolapse only or noncongenital cardiac disease were excluded. The exposure was defined by systemic ventricle.

OUTCOME MEASURES

The primary outcome was a composite of congestive heart failure, arrhythmia, stroke, cardiac arrest/death during pregnancy or postpartum (CARDCOMP). The secondary outcome (PREGCOMP) was a composite of preterm delivery, preeclampsia, growth restriction, and stillbirth/pregnancy loss (PREGCOMP). Student's t-test or chi-square/Fisher's exact tests were used for comparison of continuous/categorical variables. Multivariable logistic regression was performed to control for possible confounders.

RESULTS

One hundred forty-six pregnancies in 114 women were included; 15 (10.3%) pregnancies involved a systemic right ventricle. CARDCOMP complicated 12.3% of these pregnancies. Women with a systemic right ventricle were more likely to develop CARDCOMP even after adjustment for confounders (odds ratio [OR] 6.32 [1.7-23.5], P= .006). PREGCOMP complicated 40.4% of all pregnancies. Women with a systemic right ventricle were also more likely to develop PREGCOMP (OR 5.37 [1.4-20.7], P= .015) compared with women with a systemic left ventricle after controlling for confounders.

CONCLUSION

  In women with congenital heart disease, a systemic right ventricle is associated with adverse cardiac and pregnancy outcomes. This information is critical for counseling and caring for these women. Further investigation is warranted regarding the effect of pregnancy on long-term health for this unique cohort of women.

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.

Role of echocardiography in the assessment and management of adult congenital heart disease in pregnancy

Congenital heart disease represent a large proportion of heart disease in pregnancy. With the exception of patients with Eisenmenger's syndrome, pulmonary vascular obstructive disease, and Marfan's syndrome with aortopathy, maternal death during pregnancy is rare in women with CHD but morbidity occurs such as heart failure, arrhythmias, and stroke. Echocardiography represents a milestone in diagnosis, understanding of pathophysiology, assessment of disease severity and patient monitoring in pregnant women with unoperated and post-operative congenital heart disease.

Role of β-blocker therapy in pediatric heart failure

Heart failure is becoming an increasingly common and significant problem in the field of pediatric cardiology. The numerous types of cardiomyopathies, and more recently, long-term survival of patients with congenital heart disease, have added to a growing patient population. Over the last several decades, our knowledge base regarding mechanisms of disease and therapeutic intervention in adult patients with heart failure has drastically changed. The most recent and important breakthrough in the pharmacologic treatment of heart failure has been the particular role of β-blocker therapy. This medication has led to significant improvements in survival and symptoms in adults, with less convincing findings in limited studies in pediatrics. The ability to study the benefits of this therapy in patients has been challenging owing to the heterogeneity of the patient population and lack of large sample sizes. However, as we investigate the mechanisms behind the disease process, the differences that exist between disease conditions and ages, and the significant alterations that may exist at the molecular and genetic level, our understanding of β-blocker therapy in pediatric heart failure will improve, and ultimately may lead to patient-specific therapy.

Burden of coronary artery disease in adults with congenital heart disease and its relation to congenital and traditional heart risk factors

As adult patients with congenital heart disease (CHD) grow older, the risk of developing coronary artery disease (CAD) increases. We sought to estimate the prevalence of CAD in adult patients with CHD, the safety of coronary angiography in this setting, and the potential relation of CAD to clinical and hemodynamic parameters. Two hundred fifty adult patients with CHD (mean age 51 +/- 15 years; 53% men) underwent selective coronary angiography in our center for reasons other than suspected CAD. Clinical and hemodynamic data were retrieved retrospectively from medical records and echocardiographic and angiographic databases, respectively. Significant CAD using quantitative coronary angiography was found in 9.2% of adult patients with CHD. No patient with cyanosis or age <40 years had significant CAD. Systolic and diastolic systemic ventricular dimensions were significantly higher in patients with CAD, even after adjustment for age (odds ratio [OR] for 10-mm increase 2.59, 95% confidence interval [CI] 1.29 to 5.21, p = 0.007; OR 2.31, 95% CI 1.24 to 4.31, p = 0.008, respectively). Systemic arterial hypertension and hyperlipidemia were strong predictors of CAD (OR 4.54, 95% CI 1.82 to 12.0, p = 0.001; OR 9.08, 95% CI 3.56 to 24.54, p <0.0001, respectively), whereas no relation to chest pain was found. Only 1 major adverse event was recorded during coronary angiography. In conclusion, the prevalence of significant CAD in a hospital adult CHD cohort was similar to that in the general population. This study supported the performance of selective coronary angiography in patients >40 years referred for cardiac surgery, with low risk of major complications. Traditional cardiovascular risk factors for CAD also applied to adult patients with CHD, in whom primary prevention of CAD was as important as in the general population.

Cardiac resynchronisation therapy in paediatric and congenital heart disease: differential effects in various anatomical and functional substrates

Background:

Cardiac resynchronisation therapy (CRT) is increasingly used in children in a variety of anatomical and pathophysiological conditions, but published data are scarce.

Objective:

To record current practice and results of CRT in paediatric and congenital heart disease.

Design:

Retrospective multicentre European survey.

Setting:

Paediatric cardiology and cardiac surgery centres.

Patients:

One hundred and nine patients aged 0.24–73.8 (median 16.9) years with structural congenital heart disease (n = 87), congenital atrioventricular block (n = 12) and dilated cardiomyopathy (n = 10) with systemic left (n = 69), right (n = 36) or single (n = 4) ventricular dysfunction and ventricular dyssynchrony during sinus rhythm (n = 25) or associated with pacing (n = 84).

Interventions:

CRT for a median period of 7.5 months (concurrent cardiac surgery in 16/109).

Main outcome measures:

Functional improvement and echocardiographic change in systemic ventricular function.

Results:

The z score of the systemic ventricular end-diastolic dimension decreased by median 1.1 (p<0.001). Ejection fraction (EF) or fractional area of change increased by a mean (SD) of 11.5 (14.3)% (p<0.001) and New York Heart Association (NYHA) class improved by median 1.0 grade (p<0.001). Non-response to CRT (18.5%) was multivariably predicted by the presence of primary dilated cardiomyopathy (p = 0.002) and poor NYHA class (p = 0.003). Presence of a systemic left ventricle was the strongest multivariable predictor of improvement in EF/fractional area of change (p<0.001). Results were independent of the number of patients treated in each contributing centre.

Conclusion:

Heart failure associated with ventricular pacing is the largest indication for CRT in paediatric and congenital heart disease. CRT efficacy varies widely with the underlying anatomical and pathophysiological substrate.