Impact of pacing on systemic ventricular function in L-transposition of the great arteries

Arrhythmias in Adult Congenital Heart Disease Heart Failure

Heart failure and arrhythmias represent 2 major causes of mortality and morbidity in adults with congenital heart disease. Arrhythmias and heart failure are interdependent, and one may exacerbate the other. Treatment of one also has a positive impact on the other. Management approaches need to be multifaceted, including pharmacotherapy, optimization of hemodynamic status with catheter-based or surgical interventions, and specific management of arrhythmia with device or catheter ablation therapy.

Lead Management in Patients with Congenital Heart Disease

Pediatric patients with congenital heart disease present unique challenges when it comes to cardiac implantable electronic devices. Pacing strategy is often determined by patient size/weight and operator experience. Anatomic considerations, including residual shunts, anatomic obstructions and barriers, and abnormalities in the native conduction system, will affect the type of CIED implanted. Given the young age of patients, it is important to have an "eye on the future" when making pacemaker/defibrillator decisions, as one can expect several generator changes, lead revisions, and potential lead extractions during their lifetime.

Conduction System Pacing for Patients with Congenital Heart Disease

For patients with congenital heart disease (CHD), chronic ventricular pacing may lead to progressive cardiomyopathy owing to electromechanical dyssynchrony. Cardiac conduction system pacing (CSP) has been proposed as a physiologic pacing strategy-directly engaging the His-Purkinje system and preserving electromechanical synchrony. CSP may be indicated for a wide variety of children and adults with CHD and has emerged as an important tool in the armamentarium for cardiac implantable electronic device operators. This review provides the rationale, background, and supportive evidence for CSP in patients with CHD and discusses implant strategies and outcomes in the context of dominant ventricular morphologic categories.

Pacing in Pediatric Patients with Postoperative Atrioventricular Block

Surgery for congenital heart disease may compromise atrioventricular (AV) nodal conduction, potentially resulting in postoperative AV block. In the majority of cases, AV nodal function recovers during the early postoperative period and may only require short-term pacing support, typically provided via temporary epicardial wires. Permanent pacing is indicated when the postoperative AV block persists for more than 7 to 10 days due to the risk of mortality if a pacemaker is not implanted. Although there is a subset of patients who may have late recovery of AV nodal function, those with continued postoperative AV block will need lifelong pacing therapy.

Overview of Long-Term Outcome in Adults with Systemic Right Ventricle and Transposition of the Great Arteries: A Review

The population of patients with a systemic right ventricle (sRV) in biventricular circulation includes those who have undergone an atrial switch operation for destro-transposition of the great arteries (d-TGA) and those with congenitally corrected transposition of the great arteries (ccTGA). Despite the life expectancy of these patients is significantly increased, the long-term prognosis remains suboptimal due to late complications such as heart failure, arrhythmias, and premature death. These patients, therefore, need a close follow-up to early identify predictive factors of adverse outcomes and to implement all preventive therapeutic strategies. This review analyzes the late complications of adult patients with an sRV and TGA and clarifies which are risk factors for adverse prognosis and which are the therapeutic strategies that improve the long-term outcomes. For prognostic purposes, it is necessary to monitor sRV size and function, the tricuspid valve regurgitation, the functional class, the occurrence of syncope, the QRS duration, N-terminal pro B-type natriuretic peptide levels, and the development of arrhythmias. Furthermore, pregnancy should be discouraged in women with risk factors. Tricuspid valve replacement/repair, biventricular pacing, and implantable cardioverter defibrillator are the most important therapeutic strategies that have been shown, when used correctly, to improve long-term outcomes.

Heart failure in systemic right ventricle: Mechanisms and therapeutic options

d-loop transposition of the great arteries (d-TGA) and congenitally corrected transposition of the great arteries (cc-TGA) feature a right ventricle attempting to sustain the systemic circulation. A systemic right ventricle (sRV) cannot support cardiac output in the long run, eventually decompensating and causing heart failure. The burden of d-TGA patients with previous atrial switch repair and cc-TGA patients with heart failure will only increase in the coming years due to the aging adult congenital heart disease population and improvements in the management of advanced heart failure. Clinical data still lags behind in developing evidence-based guidelines for risk stratification and management of sRV patients, and clinical trials for heart failure in these patients are underrepresented. Recent studies have provided foundational data for the commencement of robust clinical trials in d-TGA and cc-TGA patients. Further insights into the multifactorial nature of sRV failure can only be provided by the results of such studies. This review discusses the mechanisms of heart failure in sRV patients with biventricular circulation and how these mediators may be targeted clinically to alleviate sRV failure.

Management Options for Congenitally Corrected Transposition: Which, When, and for Whom?

Management strategies for congenitally corrected transposition of the great arteries (ccTGA) historically consisted of a physiologic repair, resulting in the morphologic right ventricle (mRV) supporting systemic circulation. This strategy persisted despite the development of heart failure by middle age because of the reasonable short-term outcomes, and the natural history of some patients with favorable anatomy (felt to demonstrate the mRV's ability to function in the long-term), and due to the less-than-optimal outcomes associated with anatomical repair. As outcomes with anatomical repair improved, and the long-term risk of systemic mRV dysfunction became apparent, more have begun to realize its advantages. In addition to the decision on whether or not to pursue anatomical repair, and the optimal timing, studies demonstrating the nuance to morphologic left ventricle retraining have demonstrated its feasibility. Further considerations in ccTGA have begun to be better understood, including: the management of a poorly functioning mRV, systemic tricuspid valve regurgitation, the utility of morphologic left ventricle outflow tract obstruction (native or surgically created) and pacing strategies. While some considerations are apparent: biventricular pacing is superior to univentricular, tricuspid regurgitation must be managed early with either progression towards anatomical repair (pulmonary artery banding if needed for retraining) or tricuspid replacement (not repair) based on the patient's age; others remain to be completely elucidated. Overall, the heterogeneity of ccTGA, as well as the unique presentation with each patient regarding ventricular and valvular function and center-to-center variability in management strategies has made the interpretation of published data difficult. That said, more recent long-term outcomes favor anatomical repair in most situations.

Atrioventricular Block Necessitating Chronic Ventricular Pacing After Tricuspid Valve Surgery in Patients With a Systemic Right Ventricle: Long-Term Follow-Up

Background

Patients with transposition of the great arteries (TGA) after an atrial switch or congenitally corrected TGA (ccTGA) are prone to systemic right ventricular (sRV) failure. Tricuspid valve (TV) regurgitation aggravates sRV dysfunction. Timely TV surgery stabilizes sRV function, yet the development of atrioventricular (AV)-conduction disturbances in the course of sRV failure can contribute to sRV dysfunction through pacing-induced dyssynchrony. This study aims to explore the incidence, timing, and functional consequences of AV-block requiring ventricular pacing after TV surgery in patients with sRV.

Methods

Consecutive adolescent and adult patients with an sRV who underwent TV surgery between 1989 and 2020 and followed-up at our center were included in this observational cohort study.

Results

The data of 28 patients (53% female, 57% ccTGA, and a mean age at surgery 38 ± 13 years) were analyzed. The mean follow-up was 9.7 ± 6.8 years. Of the remaining 22 patients at the risk of developing high degree AV-block after TV surgery, 9 (41%) developed an indication for chronic ventricular pacing during follow-up, of which 5 (56%) within 24 months postoperatively (3 prior to hospital discharge). The QRS duration, a surrogate marker for dyssynchrony, was significantly higher in patients with chronic left ventricular pacing than in patients with native AV-conduction (217 ± 24 vs. 116 ± 23 ms, p = 0.000), as was the heart failure biomarker NT-pro-BNP [2,746 (1,242-6,879) vs. 495 (355-690) ng/L, p = 0.004] and the percentage of patients with ≥1 echocardiographic class of deterioration of systolic sRV function (27 vs. 83%, p = 0.001). Of the patients receiving chronic subpulmonary ventricular pacing (n = 12), 9 (75%) reached the composite endpoint of progressive heart failure [death, ventricular assist device implantation, or upgrade to cardiac resynchronization therapy (CRT)]. Only 4 (31%) patients with native AV-conduction (n = 13) reached this composite endpoint (p = 0.027).

Conclusion

Patients with a failing sRV who undergo TV surgery are prone to develop AV-conduction abnormalities, with 41% developing an indication for chronic ventricular pacing during 10 years of follow-up. Patients with chronic subpulmonary ventricular pacing have a significantly longer QRS complex duration, have higher levels of the heart failure biomarker NT-pro-BNP, and are at a higher risk of deterioration of systolic sRV function and progressive heart failure.

Complete heart block in a young adult with non-isolated congenitally corrected transposition of the great arteries: Case report

Introduction and importance

Congenitally corrected transposition of the great arteries (ccTGA) or L-looped transposition of the great arteries (L-TGA) is a very rare and complex form of congenital heart disease. The majority of patients with ccTGA have at least one or more associated congenital heart disorders, essentially ventricular septal defects. Patients with ccTGA can remain asymptomatic for a long time and the diagnosis can sometimes be made late in life at the stage of complications.

Case presentation

Here, we report a rare case of a 19-year-old patient, with no medical or surgical history, presenting a complete heart block as initial presentation of a ‘’non-isolated’’ ccTGA. The diagnosis is made essentially by echocardiography.

This case aims to show diagnostic difficulties of this rare congenital heart disease and be aware of the risk of its relative complications.

1)

Congenitally corrected transposition of the great arteries (ccTGA) is a very rare and complex form of congenital heart disease.

2)

Cardiac conduction disorders are well-established complications of ccTGA.

3)

The presence or absence of associated cardiac disorders is an important parameter to determinate the risk of chronic heart failure.

Contemporary outcomes of the double switch operation for congenitally corrected transposition of the great arteries

OBJECTIVE

To determine the contemporary outcomes of the double switch operation (DSO) (ie, Mustard or Senning + arterial switch).

METHODS

A single-institution, retrospective review of all patients with congenitally corrected transposition of the great arteries undergoing a DSO.

RESULTS

Between 1999 and 2019, 103 patients underwent DSO with a Mustard (n = 93) or Senning (n = 10) procedure. Segmental anatomy was (S, L, L) in 93 patients and (I, D, D) in 6 patients. Eight patients had heterotaxy and 71 patients had a ventricular septal defect. Median age was 2.1 years (range, 1.8 months-40 years), including 34 patients younger than age 1 year (33%). Median weight was 10.9 kg (range, 3.4-64 kg). Sixty-one patients had prior pulmonary artery bands for a median of 1.1 years (range, 14 days-12.9 years; interquartile range, 0.7-3.1 years). Median intensive care unit and hospital lengths of stay were 5 and 10 days, respectively. Median follow-up was 3.4 years (interquartile range, 1-9.8 years) and 5.2 years (interquartile range, 2.3-10.7 years) in 79 patients with >1 year follow-up. At latest follow-up, aortic, mitral, tricuspid valve regurgitation, and left ventricle dysfunction was less than moderate in 96%, 98%, 96%, and 93%, respectively. Seventeen patients underwent reoperation: neoaortic valve intervention (n = 10), baffle revision (n = 5), and ventricular septal defect closure (n = 4). At latest follow-up, 17 patients (17%) had a pacemaker and 27 (26%) had cardiac resynchronization therapy devices. There were 2 deaths and 2 transplants. Transplant-free survival was 94.6% at 5 years. Risk factors for death or transplant included longer cardiopulmonary bypass time and older age at DSO.

CONCLUSIONS

The outcomes of the DSO are promising. Earlier age at operation might favor better outcomes. Progressive neoaortic regurgitation and reinterventions on the neo-aortic valve are anticipated problems.

Cardiac resynchronization therapy in patients with congenital heart disease and systemic right ventricle

BACKGROUND

Although patients with systemic right ventricle (SRV) represent a significant proportion of patients with congenital heart disease (CHD) implanted with cardiac resynchronization therapy (CRT), there are limited and conflicting data in this specific patient group.

OBJECTIVE

We aimed to analyze outcomes of patients with SRV implanted with a CRT device.

METHODS

Data were analyzed from an observational, retrospective, multicenter cohort study including all patients with CHD implanted with a CRT device from 6 French centers from 2004 to 2020. Response to CRT was defined as an increase in systemic ventricular ejection fraction of ≥10% and/or an improvement in New York Heart Association functional class by at least 1 grade.

RESULTS

A total of 85 patients with CHD were enrolled (mean age 39.8 ± 20.0 years; 55 [64.7%] males; 25 defibrillators [29.4%]), including 31 patients with SRV (36.5%) (mean age 43.9 ± 19.8 years; 16 [51.6%] males). The mean change in QRS duration after implantation was similar as compared with patients with systemic left ventricle (-46 ± 26 ms vs -35 ± 32 ms; P = .16). During a mean follow-up of 5.1 ± 3.5 years, late complications included 2 lead dysfunctions (6.5%), 3 CRT-related infections (9.7%), and 1 inappropriate implantable cardioverter-defibrillator shock (3.2%). The proportion of CRT responders at 6, 12, and 24 months were 82.6%, 80.0%, and 77.8% in patients with SRV vs 66.7%, 64.3%, and 69.6% in patients with systemic left ventricle (P = NS).

CONCLUSION

In this multicenter cohort, one-third of patients with CHD implanted with a CRT device had SRV. CRT in patients with SRV was associated with a high rate of responders, comparable to that of patients with systemic left ventricle.

Arrhythmias in adults with congenital heart disease and heart failure

Arrhythmias and heart failure are among the most common complications encountered by adults with congenital heart disease (CHD). In this contemporary review, we explore the interactions between arrhythmias and heart failure and discuss management strategies. Major knowledge gaps are highlighted throughout. Interactions between arrhythmias and heart failure are complex and bidirectional, with one begetting the other. Arrhythmias can provoke heart failure through various mechanisms: conduction disturbances may contribute to inefficient ventricular filling and contraction patterns; bradyarrhythmias and tachyarrhythmias can result in a reduction in cardiac output; hypoxemia may be exacerbated by right-to-left shunting; and tachycardia-induced cardiomyopathy has potentially devastating consequences if the diagnosis is delayed. In turn, heart failure promotes arrhythmogenesis through various structural (eg, fibrosis, chamber dilation, hypertrophy) and electrical remodeling effects that include changes to ion currents and channels and connexin expression, along with shortening of atrial and ventricular refractory periods with increased heterogeneity. Several shared comorbidities can contribute to, and modulate the impact of, arrhythmias and heart failure. Preemptive arrhythmia management can potentially mitigate effects on heart failure exacerbations. Similarly, optimal heart failure control could curtail its impact on arrhythmogenesis. Treatment strategies to prevent or treat heart failure in adults with CHD encompass pharmacological agents, catheter ablation, and device therapies including defibrillators, cardiac resynchronization therapy, and His bundle pacing. High-priority research avenues with major knowledge gaps include tachycardia-induced cardiomyopathy, catheter ablation of atrial fibrillation, defibrillator indications in high-risk subsets, and the role of cardiac resynchronization therapy and His bundle pacing in diverse forms of CHD.

Prognostic Implications of Progressive Systemic Ventricular Dysfunction in Congenitally Corrected Transposition of Great Arteries

OBJECTIVES

The purpose of this study was to determine the risk factors for and prognostic implications of progressive right ventricular systolic dysfunction (RVD) in adults with congenitally corrected transposition of great arteries.

BACKGROUND

There are no effective therapies for RVD; hence the need to identify and modify risk factors for progressive RVD.

METHODS

RV systolic function was assessed by using RV longitudinal strain (RV-LS). The first echocardiogram (baseline echocardiogram) and all subsequent annual echocardiograms performed within 5 years from the baseline echocardiogram were analyzed. Progressive RVD (temporal decline in RV-LS) was assessed as the average annual change in RV-LS within 5 years of imaging follow-up.

RESULTS

Of 186 patients (mean age 40 ± 12 years), the RV-LS at baseline was -17% ± 4%, and the annual decline in RV-LS was -4% (95% CI: -6 to -2). The risk factors for progressive RVD were left ventricular (LV) systolic dysfunction, LV pacing, and systemic hypertension. Cardiovascular events (heart failure hospitalization, heart transplant, and death) occurred in 57 (27%) patients. Progressive RVD was associated with cardiovascular events, independent of RV systolic function at baseline. In subgroup analyses assessing impact of therapies (medical therapy, cardiac resynchronization therapy, and tricuspid valve replacement), only tricuspid valve replacement was associated with improvement in RV systolic function when performed before onset of RVD.

CONCLUSIONS

Patients with congenitally corrected transposition of great arteries were at risk for progressive RVD, and the risk factors for progressive RVD were LV pacing, systemic hypertension, and concomitant LV dysfunction. Further studies are required to determine whether strict blood pressure control and early tricuspid valve replacement will prevent progressive RVD.

Congenitally Corrected Transposition of the Great Arteries in Adults-A Contemporary Single Center Experience

BACKGROUND

Congenitally corrected transposition of the great arteries (ccTGA) is a rare congenital heart defect (CHD). Contemporary data regarding its outcome in adults are scarce.

METHODS

Retrospective, single-center study of all ccTGA patients over the age of 16 years treated at our center during the time period 2006-2018. Only patients with a biventricular circulation were included. The primary endpoint was all-cause mortality.

RESULTS

Altogether, 96 patients (mean age 32.8 ± 16.0 years, female 50%) with ccTGA and a systemic right ventricle (SRV) were included in the study. An additional CHD was present in 81 patients (84.4%); most common were a ventricular septal defect (VSD) and a left ventricular outflow tract obstruction. Out of the whole cohort, 45 (46.9%) had already undergone cardiac surgery at baseline. During a median follow-up of 6.5 (IQR 2.8-12.7) years, the primary endpoint occurred in 10 patients (10.8%). Cause of death was cardiac in nine patients and suicide in one. Hospitalizations due to heart failure occurred in 48 patients (51.6%). Upon univariate Cox analysis, an NYHA class ≥III, severe tricuspid regurgitation, severe SRV systolic impairment, as well as a reduced left ventricular systolic function were predictors of the primary endpoint. Upon multivariable analysis, only NYHA class ≥ III (HR: 18.66, CI 95%: 3.01-115.80, p = 0.0017) and a reduced left ventricular systolic function (HR: 7.36, CI 95%: 1.18-45.99, p = 0.038) remained as independent predictors.

CONCLUSIONS

Adults with ccTGA and an SRV are burdened with significant morbidity and mortality. Predictors for mortality are NYHA class and subpulmonary left ventricular function.

Isorhythmic atrioventricular dissociation in an adult with levo-transposition of the great arteries

A 36-year-old woman with levo-transposition of the great arteries presented for a programmed visit. She was asymptomatic and the clinical examination showed no signs of decompensated heart failure. Standard 12-lead ECG showed isorhythmic atrioventricular dissociation. A 24-hour ambulatory recording demonstrated sinus rhythm with intermittent periods of isorhythmic dissociation. This case highlights the association between two rare conditions.

Impact of electrophysiological features acquired after anatomical repair of congenital corrected transposition of the great arteries on late mortality and ventricular dysfunction

OBJECTIVES

In patients with anatomically repaired congenitally corrected transposition of the great arteries, the impact of electrophysiological features on postoperative ventricular dysfunction remains less well known. Our goal was to investigate the role of fragmented QRS and QRS duration in mortality and systemic ventricular dysfunction after anatomical repair of corrected transposed great arteries.

METHODS

Consecutive patients who underwent anatomical repair in our institution from January 2005 to December 2017 were enrolled in this retrospective analysis. Fragmented QRS was defined as ≥1 discontinuous deflections in narrow QRS complexes, and ≥2 in wide QRS complexes, in 2 contiguous electrocardiogram leads. The primary end point was a composite of all-cause mortality and systemic ventricular dysfunction.

RESULTS

A total of 74 patients were included. Among them, 30, 15 and 29 underwent the Senning arterial switch, the Senning Rastelli and the hemi-Mustard/bidirectional Glenn/Rastelli procedures, respectively. The primary end point occurred in 9 (12.2%) patients and included 7 late deaths and 2 cases of late-onset systemic ventricular dysfunction. Fragmented QRS and QRS prolongation were noted in 19 (25.7%) and 21 (28.4%) patients, respectively. In patients with the primary end point, QRS fragmentation (6/9 vs 10/65; P < 0.001) and QRS prolongation (6/9 vs 15/65; P = 0.013) were noted more frequently than in patients without the primary end point. No statistical differences in these electrocardiogram findings were found among patients treated with 3 surgical strategies.

CONCLUSIONS

Appearance of QRS fragmentation or QRS prolongation is associated with death or ventricular dysfunction in anatomically repaired corrected transposition of the great arteries. Although there is a trend that QRS fragmentation and QRS prolongation appear more frequently in patients who had the Senning-arterial switch operation, there is no statistically significant difference associated with these electrocardiogram features among varied procedures.

Failing systemic right ventricle in a patient with dextrocardia and complex congenitally corrected transposition of the great arteries: a case report of successful transvenous cardiac resynchronization therapy

Background 

Patients with congenitally corrected transposition of the great arteries (ccTGA) are prone to the development of advanced atrio-ventricular block requiring chronic ventricular pacing. The morphological right ventricle (RV) often develops systolic dysfunction as it is unable to withstand the chronic pressure overload it is exposed to when supporting the systemic circulation.

Case summary 

A 56-year-old woman with dextrocardia and complex ccTGA with a history of dual-chamber implantable cardioverter-defibrillator (DDD-ICD, high degree atrio-ventricular-block and syncopal ventricular tachycardia), presented with progressive heart failure and symptomatic atrial arrhythmias. She underwent a successful ablation and concomitant invasive haemodynamic evaluation of potential alternative/biventricular pacing modalities. During biventricular pacing, the QRS narrowed and the systemic RV intraventricular pressure (Dp/Dt) increased with 30%. She underwent a successful transvenous upgrade to cardiac resynchronization therapy (CRT). The electrocardiogram post-implantation showed biventricular capture and patient showed subjective and objective clinical improvement.

Discussion 

Systemic RV dysfunction in ccTGA can be aggravated by chronic pacing-induced dyssynchrony, contributing to progression of heart failure in this patient group. Transvenous CRT is feasible in ccTGA anatomy and may be pursued in order to improve or preserve the functional status of pacing-dependent ccTGA patients. Invasive haemodynamic contractility evaluation can help assess the potential benefit of CRT in patients with complex anatomy.

Transcatheter Aortic Valve Replacement in a Patient With Levo-Transposition of the Great Arteries

Levo-transposition of the great arteries is a congenital heart disease characterized by atrioventricular and ventricular-arterial discordance. Aortic valve disease in levo-transposition of the great arteries patients is uncommon. We present a patient with levo-transposition of the great arteries and severe aortic stenosis who successfully underwent transcatheter aortic valve replacement and the diagnostic and procedural challenges involved. (Level of Difficulty: Intermediate.)

Resynchronizing Right and Left Ventricles With Right Bundle Branch Block in the Congenital Heart Disease Population

OBJECTIVES

This study describes a single center experience with the use of cardiac resynchronization therapy (CRT) in a difficult patient population, including single systemic right ventricles (RVs), subpulmonary RVs, and left ventricles (LVs) with right bundle branch block (RBBB).

BACKGROUND

CRT remains challenging in the congenital heart disease population.

METHODS

Consecutive patients undergoing resynchronization of single RVs, subpulmonary RVs, or LVs in the setting of RBBB were identified between 2016 and 2019. Patients who had CRT performed for complete heart block or had <3 months of follow-up were excluded. Patients underwent pre-procedural advanced imaging by echocardiogram, computed tomography, or cardiac magnetic resonance to assess ventricular function and synchrony; intraoperative mapping was performed to identify optimal lead placement.

RESULTS

All patients undergoing resynchronization presented with at least moderate systolic ventricular dysfunction in the setting of intrinsic atrioventricular nodal conduction and RBBB. Seven patients were identified. Two patients underwent CRT of a single RV, 3 with subpulmonary RVs and 2 with systemic LVs. The median age at CRT was 5 years (range 0.6 to 48 years). The median follow-up was 9 months (range 3 to 18 months). The median baseline QRS duration was 180 ms (range 115 to 260ms). Post-CRT, the QRS duration decreased by a median of 34% (range 19% to 38%). All patients had improvement in their systolic ventricular function.

CONCLUSIONS

Targeted resynchronization in systemic and subpulmonary RVs can be used to improve ventricular function and heart failure in the congenital heart disease population. Similar techniques can be applied to successfully treat patients with LV dysfunction and RBBB and improve their long-term outcomes.

Adverse impact of univentricular pacing for the patient with functional single ventricle: successful conversion to cardiac resynchronization therapy

Background

In a Fontan candidate, univentricular pacing may cause delay in interventricular conduction, which induces asynchronous contraction. Cardiac resynchronization therapy is expected to be an effective mode of therapy in such a case.

Case presentation

A 7-month-old girl, diagnosed with dextrocardia, congenitally corrected transposition of the great artery [situs solitus, L-loop, and L-transposition], ventricular septal defect, infundibular and pulmonary valvular stenosis, and straddling of the tricuspid valve, was considered as a candidate for the Fontan procedure. She had undergone Blalock-Taussig shunt, and epicardial univentricular pacemaker implantation for persistent complete atrioventricular block. She underwent a bidirectional cavopulmonary shunt concomitant with ventricular lead translocation from the morphological left ventricle to the morphological right ventricle. After discharge, ventricular dyssynchrony was noted and cardiac failure persisted. She was converted to cardiac resynchronization therapy (CRT) at 13 months of age. Two-dimensional speckle tracking imaging was used by cardiologists to determine the most suitable pacing site. CRT rapidly corrected the heart failure; thus, she underwent the Fontan procedure after 1.5 years. Five years have passed since the cardiac resynchronization therapy; her interventricular synchrony is maintained well and the level of brain natriuretic peptide remains within normal range.

Conclusion

We describe the successful conversion from single ventricular pacing to CRT, in a case of congenitally corrected transposition of the great artery indicated for the Fontan procedure. The long-term prognosis of cardiac resynchronization therapy is undetermined in the pediatric population; therefore, further follow-up is required.

Permanent conduction system pacing for congenitally corrected transposition of the great arteries: A Pediatric and Congenital Electrophysiology Society (PACES)/International Society for Adult Congenital Heart Disease (ISACHD) Collaborative Study

BACKGROUND

Congenitally corrected transposition of the great arteries (CCTGA) is associated with spontaneous atrioventricular block and pacing-induced cardiomyopathy. Conduction system pacing is a potential alternative to conventional cardiac resynchronization therapy (CRT).

OBJECTIVE

The purpose of this study was to determine the outcomes of conduction system pacing for CCTGA.

METHODS

Retrospective data were collected from 10 international centers.

RESULTS

His bundle (HBP) or left bundle branch pacing (LBBP) was attempted in 15 CCTGA patients (median age 23 years; 87% male). Previous surgery had been performed in 8 and chronic ventricular pacing in 7. Conduction system pacing (11 HBP, 2 LBBP 2; nonselective in 10, selective in 3) was acutely successful in 13 (86%) without complication. In 9 cases, electroanatomic mapping was available and identified the distal His bundle and proximal left bundle branches within the morphologic left ventricle below the pulmonary valve separate from the mitral annulus. Median implant HV interval was 42 ms (interquartile range [IQR] 35-48), R wave 6 mV (IQR 5-18), and threshold 0.5 V (IQR 0.5-1.2) at median 0.5 ms. QRSd was unchanged compared to junctional escape rhythm (124 vs 110 ms; P = .17) and decreased significantly compared to baseline ventricular pacing (112 vs 164 ms; P <.01). At a median of 8 months, all patients were alive without significant change in pacing threshold or lead dysfunction. New York Heart Association functional class improved in 5 patients.

CONCLUSION

Permanent conduction system pacing is feasible in CCTGA by either HBP or proximal LBBP. Narrow paced QRS and stable lead thresholds were observed at intermediate follow-up. Unique anatomic characteristics may favor this approach over conventional CRT.

Trans-apical systemic tricuspid valve-in-ring replacement

Transcatheter valve replacement offers a safe and effective alternative to traditional surgical techniques in patients with congenital heart disease, especially those at high surgical risk. The most common causes of morbidity and mortality in patients with D-transposition of the great arteries status post Senning or Mustard repair is severe tricuspid valve (TV) regurgitation. Replacement of the systemic TV may be useful in those without severe systemic ventricular dysfunction. We present a case of a patient with D-loop transposition of the great arteries status post Mustard repair and TV ring placement with subsequent severe systemic TV regurgitation, at high surgical risk, who underwent a transcatheter valve replacement via a trans-apical approach using an Edwards Sapien XT valve.

Anatomic Repair of Corrected Transposition of the Great Arteries: The Double Switch

The long-term outcome of patients with corrected transposition of the great arteries and associated lesions after physiologic repair is uncertain. Anatomic correction, utilizing the morphologic left ventricle as a systemic pumping chamber and the mitral valve as the systemic atrioventricular valve, is considered the preferred method, especially for patients with either tricuspid valve regurgitation, with Ebstein's malformation of the tricuspid valve, or with right ventricular dysfunction. The double switch employs both an atrial switch and arterial switch to "correct" the atrioventricular and ventriculoarterial discordance. Associated lesions are also repaired. The best outcomes with double switch are achieved with patients in the first few years of life even if reconditioning of morphologic left ventricle is required. However, the long-term function of the conduction system, the aortic valve, and the ventricles is variable and requires close surveillance.

Surgical Outcomes of Anatomical Repair for Congenitally Corrected Transposed Great Arteries

BACKGROUND

The outcomes of anatomical repair for patients with congenitally corrected transposed great arteries remain unclear and the indications for different procedures are poorly understood.

METHODS

From January 2005 to February 2016, consecutive corrected transposition patients who underwent anatomical repair at the current institution were enrolled in this retrospective study. Varied types of anatomical repair were individually customised.

RESULTS

A total of 85 patients were included. Fifty-one (51) and 35 patients presented with left ventricular outflow tract obstruction and cardiac malposition, respectively. Thirty-nine (39) patients presented with moderate-to-severe tricuspid regurgitation. Thirty-four (34), 19, and 32 patients underwent Senning arterial switch operations, Senning-Rastelli, and hemi-Mustard-Rastelli-bidirectional Glenn, respectively. Early after repair, there were five in-hospital deaths and nine re-operations. During 4.6 years (range, 0.5-10.3) of follow-up, seven late deaths were documented. Estimated overall survival rate after anatomical repair was 89.3%, 85.0%, and 85.0% at 1 year, 3 years, and 5 years, respectively. Instead of Senning-Rastelli, most (75.0%) early left ventricular dysfunctions were noted in patients who underwent Senning arterial switch procedures. However, all the late left ventricular dysfunctions were found in patients who underwent previous left ventricular retraining. In patients with left ventricular outflow tract obstruction, the hemi-Mustard-Rastelli-bidirectional Glenn shunt provided a lower early mortality (0% vs 15.8%, p = 0.047).

CONCLUSIONS

Favourable outcomes can be achieved for anatomical repair of corrected transposition. Left ventricular dysfunction was a significant postoperative issue. Hemi-Mustard-bidirectional Glenn-Rastelli procedure may provide benefits for patients with associated left ventricular outflow tract obstruction and cardiac malposition. Each procedure has its own advantages in varied anatomy.

Myocardial fibrosis and its relation to adverse outcome in transposition of the great arteries with a systemic right ventricle

BACKGROUND

Myocardial dysfunction has been implicated in gradual heart failure in transposition of the great arteries (TGA) with a systemic right ventricle (RV). Fibrosis can be assessed using the extracellular volume fraction (ECV). Our aim was to measure ECV and determine its associations with clinical findings and outcomes.

METHODS

We prospectively measured ECV in systemic RV subjects (either D-loop after atrial switch or L-loop) and healthy controls. T₁ measurements for a single mid-ventricular short-axis plane before and 3, 7, and 15 min after gadolinium contrast were used to quantify systemic ventricular ECV. Individuals with elevated ECV were compared to those without.

RESULTS

In 53 TGA subjects (age 34.6 ± 10.3 years, 41% female) the mean ECV for the systemic RV (28.7 ± 4.4%) was significantly higher than the left ventricle in 22 controls (26.1 ± 2.8%, P = 0.0104). Those with an elevated ECV (n = 15, 28.3%) had a higher b-type natriuretic peptide (BNP) (P < 0.011) and a longer 6-min walk distance (P = 0.021), but did not differ by age, arrhythmia history, ventricular volume, function, or circulating collagen byproducts. At follow-up (median 4.4 years), those experiencing major cardiovascular endpoints (new arrhythmia, arrhythmia device, heart failure hospitalization, listing for transplantation, mechanical support, or cardiovascular death, n = 14) had a higher ECV. ECV, age, and BNP were independent predictors of cardiac events in Cox-proportional hazard models.

CONCLUSIONS

Myocardial fibrosis is common in the systemic RV and associated with a higher BNP. Elevated CMR-derived ECV was associated with adverse clinical outcome. The findings suggest a role of diffuse myocardial fibrosis in clinical deterioration of the systemic RV.

Modern Technology for Prevention of Sudden Cardiac Death – a Clinical Update on Device Therapy in Children with Congenital Heart Diseases

Sudden cardiac death in children is one of the most devastating conditions that can be encountered in acute cardiac care. Intracardiac device therapy, providing prompt and effective treatment in malignant ventricular arrhythmia or in severe conduction abnormalities, is a promising tool to reduce the incidence of this fatal condition. However, the implementation of device-based therapy in the pediatric population is currently limited by the lack of clinical studies on large number of subjects. As a result, indications for device therapy in pediatric patients are still unclear in many circumstances. There are also several particularities related to device implantation in pediatric age, such as the somatic growth leading to a mismatch between chamber size and lead length, or the difficulties of implantation technique in children with small body weight. This study aims to present an update on the current advantages and limitations of device-based therapy for treating severe malignant arrhythmia or conduction disorders in children at risk for sudden cardiac death.

Origins and consequences of congenital heart defects affecting the right ventricle

Congenital heart disease is a major health issue, accounting for a third of all congenital defects. Improved early surgical management has led to a growing population of adults with congenital heart disease, including patients with defects affecting the right ventricle, which are often classified as severe. Defects affecting the right ventricle often cause right ventricular volume or pressure overload and affected patients are at high risk for complications such as heart failure and sudden death. Recent insights into the developmental mechanisms and distinct developmental origins of the left ventricle, right ventricle, and the outflow tract have shed light on the common features and distinct problems arising in specific defects. Here, we provide a comprehensive overview of the current knowledge on the development into the normal and congenitally malformed right heart and the clinical consequences of several congenital heart defects affecting the right ventricle.

Late diagnosis of a congenitally corrected transposition of the great arteries discovered at pacemaker implantation in a patient previously diagnosed with dextrocardia and situs solitus

Congenitally corrected transposition of the great arteries (CCTGA) should not be missed in patients with dextrocardia and situs solitus. We report a case of a 56-year-old man with late diagnosis of CCTGA after ventricular lead replacement. Free LV wall pacing may be favorable in these patients so to prevent deterioration of the systemic RV function.

Systemic Right Ventricle in Adults With Congenital Heart Disease

The systemic right ventricle (SRV) is commonly encountered in congenital heart disease representing a distinctly different model in terms of its anatomic spectrum, adaptation, clinical phenotype, and variable, but overall guarded prognosis. The most common clinical scenarios where an SRV is encountered are complete transposition of the great arteries with previous atrial switch repair, congenitally corrected transposition of the great arteries, double inlet right ventricle mostly with previous Fontan palliation, and hypoplastic left heart syndrome palliated with the Norwood-Fontan protocol. The reasons for the guarded prognosis of the SRV in comparison with the systemic left ventricle are multifactorial, including distinct fibromuscular architecture, shape and function, coronary artery supply mismatch, intrinsic abnormalities of the tricuspid valve, intrinsic or acquired conduction abnormalities, and varied SRV adaptation to pressure or volume overload. Management of the SRV remains an ongoing challenge because SRV dysfunction has implications on short- and long-term outcomes for all patients irrespective of underlying cardiac morphology. SRV dysfunction can be subclinical, underscoring the need for tertiary follow-up and timely management of target hemodynamic lesions. Catheter interventions and surgery have an established role in selected patients. Cardiac resynchronization therapy is increasingly used, whereas pharmacological therapy is largely empirical. Mechanical assist device and heart transplantation remain options in end-stage heart failure when other management strategies have been exhausted. The present report focuses on the SRV with its pathological subtypes, pathophysiology, clinical features, current management strategies, and long-term sequelae. Although our article touches on issues applicable to neonates and children, its main focus is on adults with SRV.

Anatomic Repair of Congenitally Corrected Transposition of the Great Arteries: Single-Center Intermediate-Term Experience

We present our experience for patients who have undergone an anatomic repair (AR) for congenitally corrected transposition of the great arteries (CCTGA) at the Children's Hospital of Wisconsin. A retrospective chart review of patients who underwent AR for CCTGA from 2001 to 2015 was performed. The cohort consisted of 15 patients (74% male). Median age of anatomic repair was 15 months (range 4.5-45.6 months). Four patients had a bidirectional Glenn (BDG) prior to AR. At the time of AR,-9 (60%) underwent Senning/Rastelli procedure, 4 (26.6%) had double switch operation, and 2 (13.3%) underwent only Senning with VSD closure. Median duration of follow-up was 5.5 years (0.05-14 years). Reoperations prior to discharge included BDG, revision of pulmonary venous baffle, closure of residual VSD, and pacemaker placement. Late reoperations included left ventricular outflow tract obstruction repair, conduit replacement, melody valve placement, and pacemaker implantation. At their most recent follow-up, no patient had heart failure symptoms and only 1 had severely diminished function that improved with cardiac resynchronization therapy. Moderate mitral regurgitation was noted in 15% (2/13), and severe in 7% (1/13). Moderate tricuspid regurgitation was noted in 15% (2/13). One patient, 7% (1/13), developed moderate aortic insufficiency. There was a 100% survival at the time of the most recent follow-up. Patients with CCTGA who have undergone AR have excellent functional status and mid-term survival but reinterventions are common. Longer term studies are needed to determine both the extent and spectrum of reinterventions as well as long term survival.

Management of Systemic Right Ventricular Failure in Patients With Congenitally Corrected Transposition of the Great Arteries

In recent decades, significant progress has been made in the diagnosis and management of congenitally corrected transposition of the great arteries (ccTGA). Nevertheless, gradual dysfunction and failure of the right ventricle (RV) in the systemic circulation remain the main contributors to mortality and disability for patients with ccTGA, especially after adolescence. Anatomic repair of ccTGA effectively resolves the problem of failure of the systemic RV and has good early and midterm results. However, this strategy is applicable primarily in infants and children up to their teens and has associated risks and limitations, and new challenges can arise in the late postoperative period. Patients with ccTGA manifesting progressive systemic RV dysfunction beyond adolescence represent the major challenge. Several palliative options such as cardiac resynchronization therapy, tricuspid valve repair or replacement, pulmonary artery banding, and implantation of an assist device into the systemic RV can be used to improve functional status and to delay the progression of ventricular dysfunction in patients who are not suitable for anatomic correction of ccTGA. For adult patients with severe systemic RV failure, heart transplantation currently remains the only long-term lifesaving procedure, although donor organ availability remains one of the most limiting factors in this type of therapy. This review focuses on current surgical and medical strategies and interventional options for the prevention and management of systemic RV failure in adults and children with ccTGA.