Ventricular arrhythmias and sudden death in tetralogy of Fallot

Electrophysiological study prior to planned pulmonary valve replacement in patients with repaired tetralogy of Fallot

AIM

Ventricular arrhythmias (VAs) are the most common cause of death in patients with repaired Tetralogy of Fallot (rTOF). However, risk stratifying remains challenging. We examined outcomes following programmed ventricular stimulation (PVS) with or without subsequent ablation in patients with rTOF planned for pulmonary valve replacement (PVR).

METHODS

We included all consecutive patients with rTOF referred to our institution from 2010 to 2018 aged ≥18 years for PVR. Right ventricular (RV) voltage maps were acquired and PVS was performed from two different sites at baseline, and if non-inducible under isoproterenol. Catheter and/or surgical ablation was performed when patients were inducible or when slow conduction was present in anatomical isthmuses (AIs). Postablation PVS was undertaken to guide implantable cardioverter-defibrillator (ICD) implantation.

RESULTS

Seventy-seven patients (36.2 ± 14.3 years old, 71% male) were included. Eighteen were inducible. In 28 patients (17 inducible, 11 non-inducible but with slow conduction) ablation was performed. Five had catheter ablation, surgical cryoablation in 9, both techniques in 14. ICDs were implanted in five patients. During a follow-up of 74 ± 40 months, no sudden cardiac death occurred. Three patients experienced sustained VAs, all were inducible during the initial EP study. Two of them had an ICD (low ejection fraction for one and important risk factor for arrhythmia for the second). No VAs were reported in the non-inducible group (p < .001).

CONCLUSION

Preoperative EPS can help identifying patients with rTOF at risk for VAs, providing an opportunity for targeted ablation and may improve decision-making regarding ICD implantation.

Trileaflet pulmonary valve reconstruction with the Ozaki technique in an adult patient of tetralogy of Fallot with absent pulmonary valve

Pulmonary valve interventions are one of the most common cardiac interventions that are being performed in patients with a wide variety of congenital heart diseases, more so in adults with congenital heart disease. Despite the introduction of various different reconstructive techniques and conduits, the ideal option still remains elusive. Lack of growth and re-operation for conduit replacement remains an Achilles heel in such conduits. So, surgeons have constantly tried to evolve surgical techniques that would obviate their use and allow age-related growth. The Ozaki procedure has proven to be technically reproducible and have excellent mid-term results in the aortic position in adults. Extending the same principle for reconstruction of the pulmonary valve can prove to be a reasonable alternative.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-022-01469-1.

Reversal of Right Ventricular Remodeling After Correction of Pulmonary Regurgitation in Tetralogy of Fallot

In the sheep model with pathophysiologic changes similar to patients with repaired TOF, severe PR leads to fibrotic changes in the RV. Pulmonary valve replacement reverses these fibrotic changes. Early valve replacement led to a quick RV recovery, and in time there was no difference in outcome between early and late valve replacement. These data support the benefit of valve replacement for RV function and suggest that there is a margin in the timing of the surgery. The fibrotic changes correlated well with the circulating biomarker PICP, which can have an added value in the clinical follow-up of patients with repaired TOF.

Anaesthetic management of a toddler with uncorrected tetralogy of Fallot undergoing surgery for epidural haematoma

The literature on the anaesthetic management of a toddler presenting to the emergency department with an acute epidural haematoma with an uncorrected tetralogy of Fallot is sparse and management can be challenging. The main anaesthetic goals are to increase or maintain systemic vascular resistance and decrease pulmonary vascular resistance for cardiovascular stability, while maintaining cerebral perfusion pressure and decreasing intracranial pressure for cerebral protection. Thus, a balanced approach is desirable while managing such cases from emergency to the intensive care unit.

Pulmonary valve replacement: a new paradigm with tissue engineering

Prevalence of congenital heart diseases worldwide is around 9 per 1000 newborns, 20% of which affect the pulmonary valve or right ventricular outflow tract. As survival after surgical repair of these defects has improved over time, there is the need to address the long-term issues of older children and young adults with "repaired" congenital heart diseases. In recent decades, the most used types of valves are the mechanical and bioprosthetic valves. Despite improving patients' quality of life, these effects are suboptimal due to their limitations, such as the inability to grow and adapt to hemodynamic changes. These issues have led to the search for living valve solutions through tissue engineering to respond to these challenges. This review aims to review the performance of traditional pulmonary valves and understand how tissue engineering-based valves can improve the management of these patients.

Clinical Characteristics of Patients with Tetralogy of Fallot who Underwent an Invasive Procedure for Arrhythmias

Introduction: Tetralogy of Fallot (TOF) is a cyanotic congenital heart disease that has an incidence of sudden cardiac death of 0.2% per year, being arrhythmias the main cause of its occurrence. Objective: To compare characteristics of TOF patients referred for electrophysiological study (EPS) against those that were not (No-EPS). Method: Retrospective cohort with 215 patients (57.2% men; age = 29 ± 4) with corrected TOF (median of three years, ranging from 0.33 to 51) that underwent EPS between 2009-2020. The primary outcome was composed of death, implantable cardiac defibrillator (ICD) requirement and hospitalization. Results: Pre-syncope (EPS = 4.7%, No-EPS = 0%; p = 0.004), syncope (EPS = 7.1%, No-EPS = 1.7%; p = 0.056) and palpitations (EPS = 31%, No-EPS = 5.8%; p < 0.001) were symptoms that justified electrophysiological investigation. ICD was implanted in 24% of EPS and 0.6% of No-EPS (p=0.001). Twenty-six percent of the EPS group presented non-sustained ventricular tachycardia, while 0% in No-EPS (p = 0.012). The EPS group had more atrial fibrillation or atrial Flutter (35.7% vs. 6.9%; p < 0.001). The EPS patients had a wider QRS duration than the no-EPS group (171.12 ± 29.52 ms vs. 147 ± 29.77 ms; p < 0.001). Also, 26.2% of EPS performed ablation to correct macroreentrant atrial tachycardias. The incidence of primary outcome (death + ICD requirement + hospitalization) was higher in patients in the EPS group compared to the No-EPS group (p = 0.001). However, the total of seven deaths occurred during the clinical follow-up, but without differences between the groups (EPS = 4.7% vs. No-EPS = 2.8%; p = 0.480). Conclusion: EPS group had a profile of greater risk, more complex heart disease, and a greater occurrence of the primary outcome when compared to the No-EPS group.

Avalanches in cardiology

Sudden cardiac death (SCD) accounts for 15%–60% of mortality in patients with heart disease. Generally, this has been attributed to ventricular tachyarrhythmia. However, ventricular tachyarrhythmia has been documented or strongly suspected on clinical grounds in a relatively small proportion of SCD patients (8%–50%). Attempted prophylaxis of SCD by implantation of cardioverter-defibrillator is associated with variable success in different subsets of high-risk cardiac patients (30%–70%). A significant number of SCD, therefore, appear to be due to catastrophic circulatory failure. Multiple interdependent compensatory mechanisms help to maintain circulation in advanced cardiac disease. Rapid, unexpected, and massive breakdown of the compensated state can be precipitated by small and often imperceptible triggers. The initial critical but stable state followed by rapid circulatory failure and death has been considered to be analogous to snow avalanches. It is typically described in patients with left ventricular (LV) dysfunction (ischemic or nonischemic). It is now recognized that SCD can also happen in conditions where the right ventricle (RV) takes the brunt of the hemodynamic load. Advanced pulmonary arterial hypertension and operated patients of tetralogy of Fallot with pulmonary regurgitation are of particular interest to pediatric cardiologists. A large amount of data is available on LV changes and mechanics, while relatively little information is available on the mechanisms of RV adaptation to increased load and RV failure. Whether the triggers and the decompensatory processes are similar for the two ventricles is a moot point. This article highlights the currently available knowledge on the pathophysiology of SCD in RV overload states, with special reference to RV adaptive and decompensatory mechanisms, and therapeutic measures that can potentially interrupt the vicious downward course (cardiac avalanches).

QRS Duration During Follow-Up of Tetralogy of Fallot: How Valuable is it? Analysis of ECG Changes in Relation to Pulmonary Valve Implantation

Long-term results after tetralogy of Fallot (TOF) repair are determined by the extent of right ventricular remodeling to chronic pulmonary regurgitation entailing progressive RV dysfunction and a risk of developing ventricular arrhythmia. Pulmonary valve replacement (PVR) can alleviate this burden. As a predictor of ventricular arrhythmia, QRS duration remains a strong parameter in this decision. We performed a retrospective analysis of all PVR patients between 2005 and 2018, studying the time evolution of electrocardiographic parameters before and after PVR through linear mixed model analysis. 42 TOF patients underwent PVR. The median timespan between primary repair and PVR was 18 years (IQR 13-30). The indication for PVR was primarily based on the association of exercise intolerance (67%) and significant RV dilation on cMRI (median RVEDVi 161 ml/m² IQR 133-181). Median QRS length was 155 ms (IQR 138-164), 4 (10%) patients had a QRS > 180 ms. QRS duration increased significantly before PVR, but barely showed regression after PVR. Changes of QRS duration after PVR were independent of RV dilation. In conclusion, when the decision for PVR in TOF patients is primarily based on RV volume and/or function threshold, QRS duration > 180 ms is rarely observed. In contrast with the significant increase of QRS duration before PVR, QRS length regression appears to be independent of the extent of RV dilation or QRS > 160 ms. Considering that the decision for PVR is based on mechanical RV characteristics, the utility of serial follow-up of QRS duration in contemporary operated TOF patients becomes questionable in absence of clinical arguments for ventricular arrhythmia.

Electrical storm after correction of an uncomplicated congenital atrial septal defect in an adult: a case report

BACKGROUND

There is a paucity of published literature describing electrical storm after the correction of uncomplicated atrial septal defect (ASD) in an adult.

CASE PRESENTATION

We present a 49-year-old woman with a congenital ASD combined with mild tricuspid regurgitation who denied any history of arrhythmia or other medical history. She suffered from electrical storm (≥ 3 episodes of ventricular tachycardias or ventricular fibrillations) in the early stage after ASD repair with combined tricuspid valvuloplasty. During electrical storm, her electrolytes were within normal ranges and no ischemic electrocardiographic changes were detected, which suggested that retained air embolism or acute coronary thrombosis were unlikely. Additionally, echocardiographic findings and her central venous pressure (5-8 mmHg during the interval between attacks) failed to support the diagnosis of pericardial tamponade. After a thorough discussion, the surgeons conducted an emergent re-exploration and repeated closure of the ASD with combined DeVega's annuloplasty. Eventually, the patient recovered uneventfully, without reoccurring arrhythmias during follow-up. Although we fail to determine the definite cause, we speculate that the causes probably are iatrogenic injury of the conduction system due to a rare anatomic variation, poor intraoperative protection, latent coronary distortion during tricuspid valvuloplasty, or idiopathic or secondary abnormalities of the conduction system.

CONCLUSIONS

For most surgeons, performing re-exploration without a known etiology is a difficult decision to make. This case illustrates that re-exploration could be an option when electrical storm occurs in the early stage postoperatively. Nevertheless, surgeons should assess the benefit-risk ratio when taking this unconventional measure.

The challenges of an aging tetralogy of Fallot population

Introduction: Advancements in surgery and management have resulted in a growing population of aging adults with tetralogy of Fallot (TOF). As a result, there has been a parallel growth in late complications associated with the sequelae from the underlying cardiac anomalies as well as the surgical and other interventional treatments.Areas covered: Here, we review challenges related to an aging population of patients with TOF, particularly late complications, and highlight advances in management and key areas for future research. Pulmonary regurgitation, heart failure, arrhythmias, and aortic complications are some of these late complications. There is also a growing incidence of acquired cardiovascular disease, obesity, and diabetes associated with aging. Management of these late complications and acquired comorbidities continues to evolve as research provides insights into long-term outcomes from medical therapies and surgical interventions.Expert opinion: The management of an aging TOF population will continue to transform with advances in imaging technologies to identify subclinical disease and valve replacement technologies that will prevent and mitigate disease progression. In the coming years, we speculate that there will be more data to support the use of novel heart failure therapies in TOF and consensus guidelines on the management of refractory arrhythmias and aortic complications.

[The adult with tetralogy of fallot: what the clinical cardiologist needs to know]

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. After more than seven decades of the first palliative surgery, TOF prognosis has changed dramatically. The prevalence of TOF is approximately 3 per 10 000 births, representing 7 to 10% of congenital heart disease. With a higher survival into adulthood, the clinical cardiologist faces challenges in the management of this population, from severe pulmonary regurgitation to heart failure and ventricular arrhythmias. Its prevalence is approximately 3 per 10 000 live births, representing 7 to 10% of congenital heart disease. This review will describe the most relevant aspects of the care of adult patients with this disease.

Spectrum of changes on cardiac magnetic resonance in repaired tetralogy of Fallot: Imaging according to surgical considerations

Imaging of repaired tetralogy of Fallot (TOF) is one of the common indications for cardiac magnetic resonance (CMR) examinations. With advances in CMR imaging techniques like phase contrast imaging and functional imaging, it has superseded investigations like echocardiography for anatomical and functional assessment of the pathophysiological changes in repaired TOF. Common repair procedures for TOF include infundibulectomy, transannular patch repair and right ventricle to pulmonary artery (RV-PA) conduit. While each of these procedures cause dynamic changes in heart and pulmonary arteries resulting in some expected imaging findings, CMR also helps in diagnosing the complications associated with these repair procedures like pulmonary stenosis, right ventricular outflow tract aneurysm, pulmonary regurgitation, RV-PA conduit stenosis, tricuspid regurgitation, right ventricular failure, and residual ventricular septal defects. Hence, it is imperative for a radiologist to be familiar with the expected changes on CMR in repaired TOF along with some of the common complications that may be encountered on imaging in such patients.

Inappropriate implantable cardioverter-defibrillator shocks in repaired tetralogy of fallot patients: Prevalence and electrophysiological mechanisms

Background

Patients with Tetralogy of Fallot (TOF) are at increased risk for sudden cardiac death, often undergo implantable cardioverter defibrillator (ICD) implantation at younger ages, and are at greater risk of experiencing inappropriate shocks. We investigated occurrences of ICD shocks in TOF patients to identify prevalence, characteristics associated with inappropriate shocks, and therapeutic interventions after inappropriate shocks.

Methods

Records of patients with repaired TOF and ICD implantation who were followed at Columbia University Irving Medical Center between 1/1/2000 and 5/1/2019 were analyzed.

Results

44 patients with repaired TOF and ICD implantation were reviewed. Mean age at implantation was 39 ± 13 years. Eight (18%) patients received both appropriate and inappropriate shocks, 6 (14%) received only appropriate shocks, and 3 (7%) received only inappropriate shocks. Three patients received inappropriate shocks for sinus tachycardia, 7 for atrial arrhythmias, and 1 for noise artifact. Inappropriately shocked patients had lower beat per minute (bpm) cutoff values for ICD therapy (mean = 162 ± 24 bpm vs. 182 ± 16 bpm, p = 0.007). After inappropriate shocks, 1 patient underwent lead replacement, 1 had the VT cutoff increased, and 6 were treated with medications.

Conclusions

One quarter of TOF patients with ICDs experienced inappropriate shock therapy, the timing of which was most often clustered within the first two years after implant or years later. Lower shock therapy zones were associated with increased risk for inappropriate shocks, and the majority of inappropriate shocks resulted from atrial arrhythmias with rapid ventricular response. Treatments for inappropriate shocks included increasing VT therapy bpm and rhythm and/or rate control medications.

Advanced mapping strategies for ablation therapy in adults with congenital heart disease

Background

Ultra-high density mapping (HDM) is a promising tool in the treatment of patients with complex arrhythmias. In adults with congenital heart disease (CHD), rhythm disorders are among the most common complications but catheter ablation can be challenging due to heterogenous anatomy and complex arrhythmogenic substrates. Here, we describe our initial experience using HDM in conjunction with novel automated annotation algorithms in patients with moderate to great CHD complexity.

Methods

We studied a series of consecutive adult patients with moderate to great CHD complexity and an indication for catheter ablation due to symptomatic arrhythmia. HDM was conducted using the Rhythmia™ mapping system and a 64-electrode mini-basket catheter for identification of anatomy, voltage, activation pattern and critical areas of arrhythmia for ablation guidance. To investigate novel advanced mapping strategies, postprocedural signal processing using the Lumipoint™ software was applied.

Results

In 19 patients (53±3 years; 53% male), 21 consecutive ablation procedures were conducted. Procedures included ablation of atrial fibrillation (n=7; 33%), atrial tachycardia (n=11; 52%), atrioventricular accessory pathway (n=1; 5%), the atrioventricular node (n=1; 5%) and ventricular arrhythmias (n=4; 19%). A total of 23 supraventricular and 8 ventricular arrhythmias were studied with the generation of 56 complete high density maps (atrial n=43; ventricular n=11, coronary sinus n=2) and an average of 12,043±1,679 mapping points. Multiple arrhythmias were observed in n=7 procedures (33% of procedures; range of arrhythmias detected 2-4). A total range of 1-4 critical areas were defined per procedure and treated within a radiofrequency application time of 16 (interquartile range 12-45) minutes. Postprocedural signal processing using Lumipoint™ allowed rapid annotation of fractionated signals within specific windows of interest. This supported identification of a practical critical isthmus in 20 out of 27 completed atrial and ventricular tachycardia activation maps.

Conclusions

Our findings suggest that HDM in conjunction with novel automated annotation algorithms provides detailed insights into arrhythmia mechanisms and might facilitate tailored catheter ablation in patients with moderate to great CHD complexity.

Sudden Cardiac Deaths in Adults with Congenital Heart Disease with Structural Abnormalities: A Retrospective Review of Cases in the Cook County Medical Examiner's Office

Sudden cardiac death is a significant cause of mortality in adults with congenital heart disease (CHD). The Cook County Medical Examiner's Office database was queried for cases of CHD as a cause of death in the period between July 2008 and April 2019. Twenty-two cases were identified, including 11 decedents with simple defects and 10 decedents with complex defects. All of the subjects were in apparent good health at the time of death. In the absence of other obvious causes of death, simple defects were considered cases of sudden cardiac death. Significant cardiac morphological changes were common in complex defects. While 16 cases had known, diagnosed/treated CHD, 5 cases had no diagnosis prior to autopsy. In these cases, the ability to recognize CHD (sometimes subtle) helped in determining the causes of death. Therefore, forensic pathologists must be able to properly recognize various forms of CHD and request consultations, when needed.

Ventricular Arrhythmias and Sudden Cardiac Death

Ventricular arrhythmias remain a significant cause of sudden cardiac death (SCD), and knowledge of their cause and high-risk features is important. SCD occurs when the interaction between vulnerable substrates and acute triggers results in sustained ventricular tachycardia progressing to ventricular fibrillation. Here, the authors aim to review the role of ventricular arrhythmias in SCD, first by approaching the substrates that support ventricular arrhythmias, and then by exploring features of these substrates and the acute triggers that may lead to SCD.