Cardiac Conduction System in Congenitally Corrected Transposition of the Great Arteries and Its Clinical Relevance

A leadless pacemaker implantation for a patient with systemic right ventricle under ventricular assist device support

Patients with congenitally corrected transposition of the great arteries (ccTGA) often develop complete atrioventricular block and heart failure due to the abnormal disposition of atrioventricular node and disadvantage of systemic right ventricle. These issues are managed with a pacing system and a ventricular assist device (VAD), respectively. While technological advances offer new treatment strategies, the simultaneous deployment of a leadless pacemaker and a VAD in cases of ccTGA remains unexplored. Here, we present a case of leadless pacemaker implantation for a VAD-supported ccTGA patient. The safety of a leadless pacemaker for a subpulmonary left ventricle and electromagnetic interference between devices are major concerns when implanting a leadless pacemaker; however, the current case overcomes these obstacles. There were no perioperative complications, and both devices were functioning without problems during a one-year follow up. We expect that, even in patients with cardiac complexity such as systemic right ventricle under VAD support, a leadless pacemaker could become the treatment of choice if the indication is appropriate, although careful and close follow up is needed.

Learning objective

Technological advances expand treatment strategies and provide significant benefits to patients with adult congenital heart disease (ACHD). However, discussion of the combination of a leadless pacemaker and a ventricular assist device (VAD) is rare. We demonstrated the efficacy of a leadless pacemaker for a subpulmonary left ventricle in a patient with systemic right ventricle on VAD. This approach could be an option even for ACHD patients.

Clinical Factors Affecting Survival in Patients with Congenitally Corrected Transposition of the Great Arteries: A Systematic Review and Meta-Analysis

Background: Congenitally corrected transposition of the great arteries (cc-TGA) is a defect characterized by arterio-ventricular and atrioventricular disconcordance. Most patients have co-existing cardiac abnormalities that warrant further treatment. Some patients do not require surgical intervention, but most undergo physiological repair or anatomical surgery, which enables them to reach adulthood. Aims: We aimed to evaluate mortality risk factors in patients with cc-TGA. Results: We searched the PubMed database and included 10 retrospective cohort studies with at least a 5-year follow-up time with an end-point of cardiovascular death a minimum of 30 days after surgery. We enrolled 532 patients, and 83 met the end-point of cardiovascular death or equivalent event. As a risk factor for long-term mortality, we identified New York Heart Association (NYHA) class ≥III/heart failure hospitalization (OR = 10.53; 95% CI, 3.17-34.98) and systemic ventricle dysfunction (SVD; OR = 4.95; 95% CI, 2.55-9.64). We did not show history of supraventricular arrhythmia (OR = 2.78; 95% CI, 0.94-8.24), systemic valve regurgitation ≥moderate (SVR; OR = 4.02; 95% Cl, 0.84-19.18), and pacemaker implantation (OR = 1.48; 95% Cl, 0.12-18.82) to affect the long-term survival. In operated patients only, SVD (OR = 4.69; 95% CI, 2.06-10.71) and SVR (OR = 3.85; 95% CI, 1.5-9.85) showed a statistically significant impact on survival. Conclusions: The risk factors for long-term mortality for the entire cc-TGA population are NYHA class ≥III/heart failure hospitalization and systemic ventricle dysfunction. In operated patients, systemic ventricle dysfunction and at least moderate systemic valve regurgitation were found to affect survival.

Atrial tachycardia ablation through the sub-pulmonary ventricle in a patient with multiple malformations associated with congenitally corrected transposition of the great arteries and double-sided slow-pathway

A 46-year-old woman with congenitally corrected transposition of the great arteries (ccTGA) associated with dextrocardia, situs viscerus inversus, and left superior vena cava persistence presented with an incessant supraventricular tachycardia. Electrophysiological study was not conclusive in differential diagnosis of atrial tachycardia versus atypical atrioventricular (AV) nodal reentrant tachycardia, also due to the unconventional anatomy of the coronary sinus. By a comprehensive mapping of cardiac chambers, a double side slow-pathway was localized in both atrial chambers and subsequently ablated by radiofrequency delivery without tachycardia changes. Aortic root and cusps were devoid of electrical activity. The muscular part of the sub-pulmonary ventricle at the level of interatrial septum showed an earliest activation signal of -90 ms and ablation of this site was effective in abolish the tachycardia. This is the first case to report technical concerns of septal atrial tachycardia ablation in ccTGA associated with multiple anatomical malformations. Moreover, some peculiarities have been reported for the first time including the presence of double-side AV nodal slow-pathway and atypical localization of the tachycardia origin into the muscular part of the sub-pulmonary ventricle instead of posterior pulmonary cusp.

Severe Symptomatic Aortic Stenosis in an Octogenarian with Congenitally Corrected Transposition of the Great Arteries

•ccTGA accounts for 0.5%-1.4% of patients with congenital heart disease. •Patients with isolated ccTGA can remain undiagnosed for decades. •Very rarely, patients with ccTGA develop symptomatic AS. •Management of severe AS in patients with ccTGA presents unique challenges. •Transcatheter options are limited due to the unique anatomy.

A short RP tachycardia in congenitally corrected transposition. What is the mechanism?

A 51-year-old female with congenitally corrected transposition of great arteries (CCTGA), situs solitus, dextrocardia, atrial septal defect and persistent left superior vena cava underwent electrophysiology study for recurrent palpitations with documented narrow complex, short RP tachycardia. With a catheter in the region of the anterior mitral annulus, a His signal was recorded and HV interval was 35 msec. Tachycardia was induced with a ventricular extrastimulus. During the tachycardia there was 1:1 ventriculo-atrial conduction and central atrial activation with a VA interval of 20 msec. The recorded His signal could be seen after the QRS. What is the mechanism of the tachycardia?

A case report of upgrading to cardiac resynchronization therapy in a patient with congenitally corrected transposition of great arteries and dextrocardia

Background

Congenitally corrected transposition of the great arteries (CCTGA) is a rare congenital heart anomaly. Physiological correction may be associated with a long pre-symptomatic period in many patients and delayed accidental diagnosis. Additional related congenital malformations may increase the complexity of cardiac interventions.

Case summary

A 59-year-old man with known dextrocardia, situs viscerum inversus, and CCTGA was scheduled for upgrading of a dual-chamber pacemaker to cardiac resynchronization therapy to treat heart failure related to a progressive systolic dysfunction of the systemic right ventricle (RV). Because of the specific anatomy of this patient, the therapeutic procedure was complicated by the cannulation of the Marshall vein. Nevertheless, the left ventricular lead was successfully implanted into the coronary sinus lateral branch. At the 3-month follow-up, the patient remarkably reported a significant functional improvement, despite no favourable reverse remodelling of the systemic RV.

Discussion

Upgrade of a pacemaker to biventricular pacing was feasible in this patient, who had CCTGA and dextrocardia, which resulted in symptomatic improvement at follow-up. Pre-implant contrast cardiac computed tomography angiography was essential for visualizing the venous-specific anatomy in this patient, who suffered from congenital heart disease. Conduction system pacing represents a potential alternative for the patient to prevent or treat pacing-related heart failure.

Cardiac resynchronization therapy using conduction system pacing after double-switch surgery for congenitally corrected transposition of the great arteries: a case report

Background

Patients with congenitally corrected transposition of the great arteries (ccTGA) are at risk of developing conduction disease and complete atrio-ventricular block and this risk increases after corrective cardiac surgery. However, the optimum pacing modality remains controversial.

Case summary

Twelve years after a double-switch surgery with ventricular septal defect correction, a 16-year-old ccTGA female was referred with an indication for cardiac resynchronization therapy. In the absence of coronary sinus (CS) or direct access to the conduction system, several therapeutic options were considered. Finally, using a three-dimensional navigation system and customized sheaths, a left bundle branch area pacing (LBBAP) lead was successfully implanted. The implantation resulted in stable pacing parameters and positive haemodynamic changes. At 9-month follow-up, pacing parameters were stable and the patient reported a significant improvement in quality of life.

Discussion

Cardiac resynchronization therapy in adults with repaired congenital heart disease remains challenging, especially in the absence of CS or direct access to the conduction system. In such a situation, LBBAP appears as an attractive alternative pacing modality. However, pre-operative management is critical to the success of the implantation.

Congenitally corrected transposition: not correct at all

PURPOSE OF REVIEW

Congenitally corrected transposition of the great arteries is a rare congenital defect with several management options. Disagreement continues on strategies, such as anatomic repair, physiologic repair or observation-only. This review discusses recent data that provide further guidance for clinical decision-making.

RECENT FINDINGS

New data provide greater insights into practice patterns and outcomes. Recent data from high-volume centers show progressively high rates of systemic right ventricle dysfunction over time with lower rates of systemic left ventricle dysfunction following anatomic repair; there is a statistical trend towards better survival of anatomic repair patients. Data comparing anatomic repair to observation showed that anatomic repair patients had a lower hazard of reaching a composite adverse outcome. These complex operations are predominantly performed at a small subset of congenital heart surgery centers.

SUMMARY

Anatomic repair compared with physiologic repair may have better outcomes, although there are relatively high rates of morbidity for both approaches. In the patient without associated lesions, nonsurgical management can have excellent outcomes but is complicated by right ventricular failure over time. Multicenter research will help determine risk factors for bad outcomes; management at high volume, experienced centers will probably be beneficial for this complex patient population.

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.

Congenitally corrected transposition of the great arteries and implantation of a leadless pacemaker: a case report

BACKGROUND

Congenitally corrected transposition of the great arteries (ccTGA) is a rare cardiac anomaly and can lead to abnormal electrical activity of the heart. The implant of a pacemaker in such patients is more complicated than conventional operations. This case report of an adult with ccTGA who had a leadless pacemaker implant will provide a reference for diagnosing and treating such patients.

CASE PRESENTATION

A 50-year-old male patient was admitted to hospital having experienced intermittent vision loss for a month. An electrocardiogram and Holter monitoring showed intermittent third-degree atrioventricular block, and echocardiography, cardiac computed tomography and cardiac magnetic resonance imaging confirmed a diagnosis of ccTGA. A leadless pacemaker was successfully implanted into the patient's anatomical left ventricle, and the postoperative parameters were stable.

CONCLUSION

Implanting a leadless pacemaker into a patient with a rare anatomical and electrophysiological abnormality, such as ccTGA, is feasible and efficacious, but preoperative imaging evaluation is of considerable importance.

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.

Three-dimensional electroanatomical mapping guided right bundle branch pacing in congenitally corrected transposition of great arteries

Aims

The ideal pacing strategy has been the Achilles’ heel for patients with congenitally corrected transposition of great arteries (ccTGA) with bradycardia. Various pacing modalities were documented in the literature. This article describes a novel pacing strategy and its feasibility in ccTGA with an intact ventricular septum.

Methods and results

We prospectively recruited three patients with ccTGA who presented with symptomatic complete heart block to our institute and were evaluated. All patients were planned for conduction system pacing. Those who had more than moderate or severe systemic atrioventricular regurgitation and systemic ventricular dysfunction were planned for conduction system pacing with an additional lead in the coronary sinus (CS) tributary, i.e. bundle branch pacing optimized cardiac resynchronization therapy with the intention to achieve incremental benefit. Since right bundle pacing is not described previously and in view of anatomical complexity in location, three-dimensional (3D) anatomical mapping was done with the EnSite system and later right bundle capture is identified conventionally as that of a left bundle in a normal heart. All three patients have stable lead positions and adequate thresholds at short-term follow-up.

Conclusion

In this report, we demonstrated the feasibility of permanent physiological pacing of the systemic ventricle by capturing the right bundle with 3D anatomical mapping guidance, which results in physiological activation of the systemic ventricle.

In vivo visualization and molecular targeting of the cardiac conduction system

Accidental injury to the cardiac conduction system (CCS), a network of specialized cells embedded within the heart and indistinguishable from the surrounding heart muscle tissue, is a major complication in cardiac surgeries. Here, we addressed this unmet need by engineering targeted antibody-dye conjugates directed against the CCS, allowing for the visualization of the CCS in vivo following a single intravenous injection in mice. These optical imaging tools showed high sensitivity, specificity, and resolution, with no adverse effects on CCS function. Further, with the goal of creating a viable prototype for human use, we generated a fully human monoclonal Fab that similarly targets the CCS with high specificity. We demonstrate that, when conjugated to an alternative cargo, this Fab can also be used to modulate CCS biology in vivo, providing a proof of principle for targeted cardiac therapeutics. Finally, in performing differential gene expression analyses of the entire murine CCS at single-cell resolution, we uncovered and validated a suite of additional cell surface markers that can be used to molecularly target the distinct subcomponents of the CCS, each prone to distinct life-threatening arrhythmias. These findings lay the foundation for translational approaches targeting the CCS for visualization and therapy in cardiothoracic surgery, cardiac imaging, and arrhythmia management.

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.

Familial Recurrence Patterns in Congenitally Corrected Transposition of the Great Arteries: An International Study

BACKGROUND

Congenitally corrected transposition of the great arteries (ccTGA) is a rare disease of unknown cause. We aimed to better understand familial recurrence patterns.

METHODS

An international, multicentre, retrospective cohort study was conducted in 29 tertiary hospitals in 6 countries between 1990 and 2018, entailing investigation of 1043 unrelated ccTGA probands.

RESULTS

Laterality defects and atrioventricular block at diagnosis were observed in 29.9% and 9.3%, respectively. ccTGA was associated with primary ciliary dyskinesia in 11 patients. Parental consanguinity was noted in 3.4% cases. A congenital heart defect was diagnosed in 81 relatives from 69 families, 58% of them being first-degree relatives, including 28 siblings. The most prevalent defects in relatives were dextro-transposition of the great arteries (28.4%), laterality defects (13.6%), and ccTGA (11.1%); 36 new familial clusters were described, including 8 pedigrees with concordant familial aggregation of ccTGA, 19 pedigrees with familial co-segregation of ccTGA and dextro-transposition of the great arteries, and 9 familial co-segregation of ccTGA and laterality defects. In one family co-segregation of ccTGA, dextro-transposition of the great arteries and heterotaxy syndrome in 3 distinct relatives was found. In another family, twins both displayed ccTGA and primary ciliary dyskinesia.

CONCLUSIONS

ccTGA is not always a sporadic congenital heart defect. Familial clusters as well as evidence of an association between ccTGA, dextro-transposition of the great arteries, laterality defects and in some cases primary ciliary dyskinesia, strongly suggest a common pathogenetic pathway involving laterality genes in the pathophysiology of ccTGA.

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.

Complementary Pharmacotherapy for STEMI Undergoing Primary PCI: An Evidence-Based Clinical Approach

Antithrombotic therapy is the cornerstone of pharmacological treatment in patients undergoing primary percutaneous coronary intervention (PCI). However, the acute management of ST elevation myocardial infarction (STEMI) patients includes therapy for pain relief and potential additional strategies for cardioprotection. The safety and efficacy of some commonly used treatments have been questioned by recent evidence. Indeed a concern about morphine use is the interaction between opioids and oral P2Y₁₂ inhibitors; early beta-blocker treatment has shown conflicting results for the improvement of clinical outcomes; and supplemental oxygen therapy lacks benefit in patients without hypoxia and may be of potential harm. Other additional strategies remain disappointing; however, some treatments may be selectively used. Therefore, we intend to present a critical updated review of complementary pharmacotherapy for a modern treatment approach for STEMI patients undergoing primary PCI.

Catheter ablation of atrial arrhythmias in patients post-Fontan

Atrial arrhythmias are highly prevalent in the aging Fontan population and contribute importantly to morbidity and mortality. Although the most common arrhythmia is scar-based intra-atrial re-entrant tachycardia, various other arrhythmias may occur including focal atrial tachycardia, atrioventricular node-dependent tachycardias, and atrial fibrillation. The type and prevalence of atrial arrhythmia is determined, in part, by the underlying congenital defect and variant of Fontan surgery. While the cumulative incidence of atrial tachyarrhythmias has decreased substantially from the atriopulmonary anastomosis to the more recent total cavopulmonary connection Fontan, the burden of atrial arrhythmias remains substantial. Management is often multi-faceted and can include anticoagulation, anti-arrhythmic drug therapy, pacing, and cardioversion. Catheter ablation plays a key role in arrhythmia control. Risks and benefits must be carefully weighed. Among the important considerations are the clinical burden of arrhythmia, ventricular function, hemodynamic stability in tachycardia, suspected arrhythmia mechanisms, risks associated with anaesthesia, venous access, approaches to reaching the pulmonary venous atrium, and accompanying co-morbidities. Careful review of surgical notes, electrocardiographic tracings, and advanced imaging is paramount, with particular attention to anatomic abnormalities such as venous obstructions and displaced conduction systems. Despite numerous challenges, ablation of atrial arrhythmias is effective in improving clinical status. Nevertheless, onset of new arrhythmias is common during long-term follow-up. Advanced technologies such as high-density mapping catheters and remote magnetic guided ablation carry the potential to further improve outcomes. Fontan patients with atrial arrhythmias should be referred to centers with dedicated expertise in congenital heart disease including catheter ablation, anaesthesia support, and advanced imaging.

Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in Patients With Congenital Heart Disease

Atrioventricular (AV) nodal reentrant tachycardia represents the most common regular supraventricular arrhythmia in humans, and catheter ablation of the so called slow AV nodal pathway has been effectively performed for decades. In patients with congenital heart disease, a combination of different factors makes catheter ablation of AV nodal reentrant tachycardia substrate particularly challenging, including abnormal venous access to intracardiac structures, abnormal intracardiac anatomy, potentially deviant and often unpredictable sites of the specific conduction system, loss of traditional anatomic landmarks, and congenital cardiac surgery that may complicate the access to the AV nodal area. Published experiences have confirmed the efficacy and the relative safety of such procedures when performed by experts, but the risk of complications, in particular AV block, remains non-negligible. A thorough knowledge and understanding of anatomic and electrical specificities according to underlying phenotype are essential in addressing these complex cases. Considering the major consequences associated with AV block in patients with complex congenital heart disease, particularly those without low risk access for transvenous ventricular pacing (eg, single ventricle physiology or Eisenmenger syndrome), the individual risk-benefit ratio should be carefully evaluated. The decision to defer ablation may be the wisest approach in selected patients with either infrequent or hemodynamically tolerated arrhythmias, or when the location of the AV conduction pathways remains uncertain. This narrative review aims to synthetize existing literature on catheter ablation of AV nodal reentrant tachycardia in congenital heart disease, to present main features of common associated pathologies, and to discuss approaches to mapping and safely ablating the slow AV nodal pathway in challenging cases.

Contraction patterns of the systemic right ventricle: a three-dimensional echocardiography study

AIMS

To investigate contraction patterns of the systemic right ventricle (SRV) in patients with transposition of great arteries (TGA) post-atrial switch operation and with congenitally corrected transposition of great arteries (ccTGA).

METHODS AND RESULTS

Right ventricular (RV) volumes and ejection fraction (EF) were measured by three-dimensional echocardiography in 38 patients with the SRV (24 TGA and 14 ccTGA; mean age 45 ± 12 years, 63% male), and in 38 healthy volunteers. The RV contraction was decomposed along the longitudinal, radial, and anteroposterior directions providing longitudinal, radial, and anteroposterior EF (LEF, REF, and AEF, respectively) and their contributions to total right ventricular ejection fraction (LEFi, REFi, and AEFi, respectvely). SRV was significantly larger with lower systolic function compared with healthy controls. SRV EF and four-chamber longitudinal strain strongly correlated with B-type natriuretic peptide (BNP) level (Rho -0.73, P < 0.0001 and 0.70, P < 0.0001, respectively). In patients with TGA, anteroposterior component was significantly higher than longitudinal and radial components (AEF 17 ± 4.5% vs. REF 13 ± 4.9% vs. LEF 10 ± 3.3%, P < 0.0001; AEFi 0.48 ± 0.09 vs. REFi 0.38 ± 0.1 vs. LEFi 0.29 ± 0.08, P < 0.0001). In patients with ccTGA, there was no significant difference between three SRV components. AEFi was significantly higher in TGA subgroup compared with ccTGA (0.48 ± 0.09 vs. 0.36 ± 0.08, P = 0.0002).

CONCLUSION

Contraction patterns of the SRV are different in TGA and ccTGA. Anteroposterior component is dominant in TGA providing compensation for impaired longitudinal and radial components, while in ccTGA all components contribute equally to the total EF. SRV EF and longitudinal strain demonstrate strong correlation with BNP level and should be a part of routine echocardiographic assessment of the SRV.

Angiography-guided mid/high septal implantation of ventricular leads in patients with congenital heart disease

BACKGROUND

Conduction system pacing prevents pacing-induced cardiomyopathy, but it can be challenging to perform in patients with congenital heart disease (CHD), and mid/high septal lead implantation is an alternative. This study aimed to assess intraprocedural angiography's utility as a guide for mid/high-septal lead implantation in CHD patients.

METHODS

The study subjects were CHD patients with Class I/IIa indications for permanent pacemaker implantation. To guide septal lead implantation, we performed an intraprocedural right ventricular angiogram in anteroposterior, 40° left anterior oblique, and 30° right anterior oblique. The primary endpoint was the lead tip in the mid/high septum on computed tomography (CT). The secondary endpoints were complications and systemic ventricular function on follow-up.

RESULTS

From January 2008 to December 2018, we enrolled 27 patients (mean age: 30 ± 20 years; M:F 17:10) with CHD (unoperated: 20, operated: 7). The mean paced QRS duration was 131.7 ± 5.8 ms, and CT done in 22/27 patients confirmed the lead tip in the mid-septum in 16, high septum in 5, and apical septum in 1 patient. There were no procedural complications, and during a mean follow-up of 58 ± 35.2 months, there was no significant change in the systemic ventricular ejection fraction (56.4 ± 8.3% vs 53.9 + 5.9%, P = .08). Two patients with Eisenmenger syndrome died because of refractory heart failure.

CONCLUSIONS

Intraprocedural angiography is safe and useful to guide mid/high-septal lead implantation in CHD patients. Mid/high septal lead position preserves systemic ventricular function in patients with CHD during medium-term follow-up.

Pharmacologic Inhibition of Pain Response to Incomplete Vascular Occlusion Blunts Cardiovascular Preconditioning Response

Complete vascular occlusion to distant tissue prior to an ischemic cardiac event can provide significant cardioprotection via remote ischemic preconditioning (RIPC). Despite understanding its mechanistic basis, its translation to clinical practice has been unsuccessful, likely secondary to the inherent impossibility of predicting (and therefore preconditioning) an ischemic event, as well as the discomfort that is associated with traditional, fully occlusive RIPC stimuli. Our laboratory has previously shown that non-occlusive banding (NOB) via wrapping of a leather band (similar to a traditional Jewish ritual) can elicit an RIPC response in healthy human subjects. This study sought to further the pain-mediated aspect of this observation in a mouse model of NOB with healthy mice that were exposed to treatment with and without lidocaine to inhibit pain sensation prior to ischemia/reperfusion injury. We demonstrated that NOB downregulates key inflammatory markers resulting in a preconditioning response that is partially mediated via pain sensation.

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.

Atypical twin atrioventricular nodal re-entrant tachycardia in a congenitally corrected transposition of the great arteries patient with a surgical repair of a ventricular septal defect: a case report

Background

Twin atrioventricular (AV) nodal tachycardia is a rare mechanism of supraventricular arrhythmia, only seen in some specific congenital heart defects (CHD). It consists of a re-entrant circuit between two distinct AV nodes (anterior and inferior). Since both nodes have antegrade and retrograde conduction, there is usually two QRS morphologies in sinus rhythm.

Case summary

This case is about an atypical twin AV nodal tachycardia in a 15 years old patient with congenitally corrected transposition of the great arteries and previous history of a ventricular septal defect repair. The surgical closure was probably responsible of a poor antegrade conduction over the inferior AV node, which was responsible for a unique QRS morphology. He finally received a catheter ablation of the inferior AV node. He remained asymptomatic without anti-arrhythmic drugs at 8-months post-ablation.

Discussion

Twin AV nodal re-entrant tachycardia is a rare phenomenon. The presentation and electrophysiological study can be both atypical due to previous surgical repair. The operator should be aware of specific CHD where twin AV nodal re-entrant tachycardias are expected.

Management of Congenitally Corrected Transposition of the Great Arteries With Intact Ventricular Septum: Anatomic Repair or Palliative Treatment?

[Figure: see text].

Congenitally corrected transposition of the great arteries (CCTGA)

A 33-year-old man presented with a 3-week history of breathlessness and cough. He disclosed that he was informed regarding a heart defect as a child in his home country but was unaware of its nature and was never followed up. Examination revealed a pansystolic murmur (loudest at the apex), a hyperdynamic, displaced apex, and pulmonary oedema. An ECG showed atrial fibrillation with a regular broad-complex ventricular rhythm. Following electrical cardioversion, the ECG revealed complete heart block, therefore explaining the regular atrial fibrillation. An urgent transthoracic echocardiography (TTE) confirmed the anatomy of congenitally corrected transposition of the great arteries (CCTGA) with torrential tricuspid regurgitation and impaired systemic right ventricle. Cardiac MRI identified a ventricular septal defect which was not visible on TTE. The patient showed a transient improvement following fluid offloading and ACE inhibition, with a more definitive improvement after cardiac resynchronisation therapy (CRT).

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.

Long-term outcomes of arrhythmia and distinct electrophysiological features in congenitally corrected transposition of the great arteries in an Asian cohort

Congenitally corrected transposition of the great arteries (ccTGA) is associated with various types of arrhythmia, including supraventricular tachycardia (SVT) and complete atrioventricular block (cAVB). Our study aims to characterize the arrhythmia burden, associated risk factors, arrhythmia mechanisms, and the long-term follow-up results in patients with ccTGA in a large Asian cohort.

METHODS

We enrolled 104 patients (43 women and 61 men) diagnosed with ccTGA at our institution. The mean age at last follow-up was 20.8 years.

RESULTS

For 40 patients (38%) with tachyarrhythmia, paroxysmal SVT (PSVT) and atrial arrhythmia were observed in 17 (16%) and 27 (26%) patients, respectively, with 4 patients (4%) having both types of SVT. The 20-year and 30-year SVT-free survival rates were 68% and 54%, respectively. Seven patients (7%) developed cAVB: 2 (2%) developed spontaneously, and the other 5 (5%) was surgically complicated (surgical risk of cAVB: 7%, all associated with ventricular septal defect repair surgery). PSVT was mostly associated with accessory pathways (5/9) but also related to twin atrioventricular nodal reentry tachycardia (3/9) and atrioventricular nodal reentry tachycardia (1/9). Most of the accessory pathways were located at tricuspid valve (9/10). Catheter ablation successfully eliminated all PSVT substrates (10/10) and most of the atrial arrhythmia substrates (3/5), with low recurrence rate.

CONCLUSIONS

The arrhythmia burden in patients with ccTGA is high and increases over time. However, cAVB incidence was relatively low and kept stationary in this Asian cohort. The mechanisms of SVT are complicated and can be controlled through catheter ablation.

Congenitally corrected transposition of great arteries: a case series of five unoperated African children

Background

Congenitally corrected transposition of great arteries (ccTGA) is rare. It is commonly associated with ventricular septal defect (VSD), pulmonary stenosis and heart block. Early anatomic repair is recommended between 3 and 6 months of age to prevent development of tricuspid valve regurgitation and systemic right ventricular failure.

Case presentation

We retrospectively identified five cases of ccTGA. Cases were between one and 13 years of age. All the cases were unoperated. Four of the five cases had associated intracardiac defects/complications. These included: VSD, pulmonary stenosis, tricuspid valve regurgitation, right ventricular systolic dysfunction and heart block.

Conclusion

These cases demonstrate the challenges of access to early diagnosis and surgery in a low resource setting. This delay in anatomic repair leads to complications of tricuspid valve regurgitation and systemic right ventricular failure.

Successful Catheter Ablation of Two Macro-reentrant Atrial Tachycardias in a Patient with Congenitally Corrected Transposition of the Great Arteries: A Case Report

Adults with congenital heart disease represent a complex and growing patient population. By virtue of their variant anatomy and the complex surgical repair often required in infancy, these patients are at risk of developing unique atrial and ventricular arrhythmias throughout their lifetimes. Electrophysiologists involved in the care of these patients should have a detailed understanding of their underlying anatomy and any prior surgical procedures to guide procedural planning and should have knowledge of the range of possible arrhythmia mechanisms that may differ from patients without structural heart disease. Despite this complexity, standard mapping techniques and electrophysiologic maneuvers may still be used to elucidate arrhythmia mechanisms, map tachycardia circuits, and guide catheter ablation. We report a case of two different macroreentrant right atrial tachycardias that were successfully ablated in a patient with congenitally-corrected transposition of the great arteries.

Systematic review and meta-analysis of outcomes of anatomic repair in congenitally corrected transposition of great arteries

BACKGROUND

Treatment of congenitally corrected transposition of great arteries (cc-TGA) with anatomic repair strategy has been considered superior due to restoration of the morphologic left ventricle in the systemic circulation. However, data on long term outcomes are limited to single center reports and include small sample sizes.

AIM

To perform a systematic review and meta-analysis for observational studies reporting outcomes on anatomic repair for cc-TGA.

METHODS

MEDLINE and Scopus databases were queried using predefined criteria for reports published till December 31, 2017. Studies reporting anatomic repair of minimum 5 cc-TGA patients with at least a 2 year follow up were included. Meta-analysis was performed using Comprehensive meta-analysis v3.0 software.

RESULTS

Eight hundred and ninety-five patients underwent anatomic repair with a pooled follow-up of 5457.2 patient-years (PY). Pooled estimate for operative mortality was 8.3% [95% confidence interval (CI): 6.0%-11.4%]. 0.2% (CI: 0.1%-0.4%) patients required mechanical circulatory support postoperatively and 1.7% (CI: 1.1%-2.4%) developed post-operative atrioventricular block requiring a pacemaker. Patients surviving initial surgery had a transplant free survival of 92.5% (CI: 89.5%-95.4%) per 100 PY and a low rate of need for pacemaker (0.3/100 PY; CI: 0.1-0.4). 84.7% patients (CI: 79.6%-89.9%) were found to be in New York Heart Association (NYHA) functional class I or II after 100 PY follow up. Total re-intervention rate was 5.3 per 100 PY (CI: 3.8-6.8).

CONCLUSION

Operative mortality with anatomic repair strategy for cc-TGA is high. Despite that, transplant free survival after anatomic repair for cc-TGA patients is highly favorable. Majority of patients maintain NYHA I/II functional class. However, monitoring for burden of re-interventions specific for operation type is very essential.

Systemic right ventricle in elderly patients with congenitally corrected transposition of the great arteries: Clinical profile, cardiac biomarkers, and echocardiographic parameters

OBJECTIVE

The number of patients with congenitally corrected transposition of the great arteries (ccTGA) surviving to old age is increasing. This study therefore sought to characterize 'geriatric' systemic right ventricle (sRV) in terms of clinical profile, cardiac biomarkers, and echocardiography-derived function when compared with findings in younger patients.

METHODS

A single-center cross-sectional study of adults with ccTGA was performed. Patients underwent clinical assessment; transthoracic echocardiography; and venous blood sampling including N-terminal pro-B-type natriuretic peptide (NTproBNP), galectin-3, and soluble suppression of tumorgenicity 2 (sST2) measurements. In the echocardiographic study, the sRV function was assessed using fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), systolic pulsed-wave Doppler velocity (s'), and longitudinal strain (LS).

RESULTS

Ten patients with ccTGA aged 60 years or older and 53 patients younger than 60 years of age were included. There were significantly more individuals with hypertension (40% vs. 5.7%), dyslipidaemia (50% vs. 5.7%), and atrial fibrillation (70% vs. 20.7%) in the older group; similarly, we found higher NTproBNP (2706 pg/mL vs. 784.7 pg/mL; p<0.001), and galectin-3 (10.15 ng/mL vs. 7.24 ng/mL; p=0.007) concentrations in elderly ccTGA individuals, while sST2 content did not vary significantly according to age. Upon echocardiographic assessment, lower sRV FAC (28.6% vs. 36.1%; p=0.028) and LS (-12% vs. -15.5%; p=0.017) values were observed in patients aged 60 years or older. TAPSE and s' did not differ between the age groups.

CONCLUSION

Careful screening for acquired comorbidities, particularly atrial fibrillation, in elderly ccTGA patients is warranted. Examining selected cardiac biomarkers and echocardiography-derived parameters are useful in the assessment of the aging sRV.

Intraoperative localization of cardiac conduction tissue regions using real-time fibre-optic confocal microscopy: first in human trial

OBJECTIVES

The aim of this study was to evaluate the feasibility and safety of fibre-optic confocal microscopy (FCM) using fluorescein sodium dye for the intraoperative location of conduction tissue regions during paediatric heart surgery.

METHODS

The pilot study included 6 patients undergoing elective surgery for the closure of isolated secundum atrial septal defect aged 30 days to 21 years. FCM imaging was integrated within the normal intraoperative protocol for atrial septal defect repair. Fluorescein sodium dye was applied on the arrested heart. FCM images were acquired at the atrioventricular node region, sinus node region and right ventricle (RV). Total imaging time was limited to 3 min. Any adverse events related to the study were recorded and analysed. Subjects received standard postoperative care. Trained reviewers (n = 9) classified, de-identified and randomized FCM images (n = 60) recorded from the patients as presenting striated, reticulated or indistinguishable microstructures. The reliability of reviewer agreement was assessed using Fleiss' kappa.

RESULTS

The FCM imaging instruments were integrated effectively into the cardiac surgery operating room. All adverse events found in the study were deemed expected and not related to FCM imaging. Reticulated myocardial microstructures were found during FCM imaging at atrioventricular node and sinus node regions, while striated microstructures were observed in RV. Reliability of agreement of reviewers classifying the FCM images was high (Fleiss' kappa: 0.822).

CONCLUSIONS

FCM using fluorescein sodium dye was found to be safe for use during paediatric heart surgery. The study demonstrates the potential for FCM to be effective in identifying conduction tissue regions during congenital heart surgery.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03189134.

Toward detection of conduction tissue during cardiac surgery: Light at the end of the tunnel?

Postoperative conduction block requiring lifetime pacemaker placement continues to be a considerable source of morbidity for patients undergoing repair of congenital heart defects. Damage to the cardiac conduction system (CCS) during surgical procedures is thought to be a major cause of conduction block. Intraoperative identification and avoidance of the CCS is thus a key strategy to improve surgical outcomes. A number of approaches have been developed to avoid conduction tissue damage and mitigate morbidity. Here we review the historical and contemporary approaches for identification of conduction tissue during cardiac surgery. The established approach for intraoperative identification is based on anatomic landmarks established in extensive histologic studies of normal and diseased heart. We focus on landmarks to identify the sinus and atrioventricular nodes during cardiac surgery. We also review technologies explored for intraoperative tissue identification, including electrical impedance measurements and electrocardiography. We describe new optical approaches, in particular, and optical spectroscopy and fiberoptic confocal microscopy (FCM) for identification of CCS regions and working myocardium during surgery. As a template for translation of future technology developments, we describe research and regulatory pathways to translate FCM for cardiac surgery. We suggest that along with more robust approaches to surgeon training, including awareness of fundamental anatomic studies, optical approaches such as FCM show promise in aiding surgeons with repairs of heart defects. In particular, for complex defects, these approaches can complement landmark-based identification of conduction tissue and thus help to avoid injury to the CCS due to surgical procedures.

Autopsy in adults with congenital heart disease (ACHD)

The adult congenital heart diseases (ACHD) population is exceeding the pediatric congenital heart diseases (CHD) population and is progressively expanding each year, representing more than 90% of patients with CHD. Of these, about 75% have undergone surgical and/or percutaneous intervention for palliation or correction. Autopsy can be a very challenging procedure in ACHD patients. The approach and protocol to be used may vary depending on whether the pathologists are facing native disease without surgical or percutaneous interventions, but with various degrees of cardiac remodeling, or previously palliated or corrected CHD. Moreover, interventions for the same condition have evolved over the last decades, as has perioperative myocardial preservations and postoperative care, with different long-term sequelae depending on the era in which patients were operated on. Careful clinicopathological correlation is, thus, required to assist the pathologist in performing the autopsy and reaching a diagnosis regarding the cause of death. Due to the heterogeneity of the structural abnormalities, and the wide variety of surgical and interventional procedures, there are no standard methods for dissecting the heart at autopsy. In this paper, we describe the most common types of CHDs that a pathologist could encounter at autopsy, including the various types of surgical and percutaneous procedures and major pathological manifestations. We also propose a practical systematic approach to the autopsy of ACHD patients.

Incidental congenitally corrected transposition of the great arteries (ccTGA) in an adult with suspected coronary artery disease: review on radiological features and pathophysiology

We report a case of a 46-year-old woman who has presented to a peripheral hospital with progressive exertional dyspnoea and chest discomfort. The resting ECG showed features of left-sided ventricular hypertrophy. The initial chest radiograph was reported as cardiomegaly. Initial echocardiography revealed left atrial dilatation and ‘left ventricular’ hypertrophy with normal ejection fraction. She was treated as possible coronary artery disease and was subsequently referred to our centre for CT coronary angiography. Findings from the CT scan were consistent with congenitally corrected transposition of the great arteries (ccTGA). This report describes the radiological features of ccTGA, its associated cardiovascular anomalies, pathophysiology and potential complications.

Pacing in Patients with Congenital Heart Disease: When Is It Helpful and When Is It Harmful?

PURPOSE OF REVIEW

Pacing in pediatric and adult patients with congenital heart disease requires careful evaluation and thoughtful planning. Review of current guidelines with assessment of risk/benefit must be performed along with planning on a case-by-case basis in order to achieve maximal success and reduce risk in this specialized population of patients that is rapidly increasing in size.

RECENT FINDINGS

Guidelines for pacing in pediatric and congenital heart disease patients span many years. Most recent consensus and summary guidelines address pacing in adult patients with or without congenital heart disease. Pediatric recommendations from prior documents must be included in current decision-making. Pacing in pediatric and congenital heart disease patients is important therapy. Creation of an individualized plan of care with attention to risk/benefit decision-making regarding when and how to pace is critical in this population to maximize beneficial outcome.

Multi-Scale Assessments of Cardiac Electrophysiology Reveal Regional Heterogeneity in Health and Disease

The left and right ventricles of the four-chambered heart have distinct developmental origins and functions. Chamber-specific developmental programming underlies the differential gene expression of ion channel subunits regulating cardiac electrophysiology that persists into adulthood. Here, we discuss regional specific electrical responses to genetic mutations and cardiac stressors, their clinical correlations, and describe many of the multi-scale techniques commonly used to analyze electrophysiological regional heterogeneity.