Outcomes After Late Reoperation in Patients With Repaired Tetralogy of Fallot: The Impact of Arrhythmia and Arrhythmia Surgery

Pulmonic regurgitation and management challenges in the adult with tetralogy of fallot

OPINION STATEMENT

Patients with tetralogy of Fallot (TOF) are living longer than ever because of advances in surgery in childhood since the 1950s. However, surgery in childhood is not a cure and remains only a palliative procedure because almost all patients will require further intervention throughout life. The most common intervention required in adulthood is pulmonary valve replacement (PVR) because of residual pulmonary regurgitation leading to right ventricular dilation and eventual dysfunction. The most appropriate timing for PVR remains difficult to determine and is based on many factors. Our practice is to weigh not only objective factors such as right ventricular size and function but also careful objective assessment of the patient's current quality of life and functional status.

Timing and technique of pulmonary valve replacement in the patient with tetralogy of Fallot

Residual right ventricular (RV) outflow tract pathology is universal among patients with repaired tetralogy of Fallot, and pulmonary regurgitation (PR) is also commonly present. Although tolerated in early life, by the second decade of life PR is associated with an increased risk of death because of ventricular arrhythmias. Pulmonary valve replacement (PVR) is a safe procedure that will eliminate PR, but timing and indications are evolving. Patients with arrhythmias or prolonged QRS duration are candidates for PVR. Patients with symptomatic exercise intolerance are likely to have improvement in symptoms and quality of life and should be offered PVR. Cardiac magnetic resonance has become an essential component of the management of the patient with tetralogy of Fallot with PR, and has identified the potential for and limitations of RV remodeling following PVR. Among patients with severe RV enlargement, particularly those with diminished RV or left ventricular function, there is an increased risk of adverse events and even asymptomatic patients with severe PR should be considered for PVR. Valve replacement is accomplished with homografts or heterografts, either stented bioprosthetic valves or valved conduits. In a retrospective analysis of the Children's Hospital of Wisconsin experience with PVR, there was no difference in survival or freedom from reintervention between heterografts and homografts.

Ablation of atrial tachyarrhythmias late after surgical repair of tetralogy of Fallot

BACKGROUND

Patients with repaired tetralogy of Fallot may develop symptomatic and haemodynamic deterioration for many reasons such as arrhythmia, pulmonary regurgitation, and impairment in ventricular function. We describe a consecutive group of patients whose main clinical problem was atrial tachyarrhythmias.

AIMS

To describe the clinical outcome of atrial tachyarrhythmias occurring late after surgical repair of tetralogy of Fallot; to define the circuits/foci responsible for these atrial tachyarrhythmias; to evaluate the outcome of computer-assisted mapping and catheter ablation in this patient group.

METHODS AND RESULTS

Consecutive patients with surgically repaired tetralogy of Fallot and atrial tachyarrhythmias, who underwent catheter ablation between January, 2001 and June, 2007, were identified retrospectively from case records. Computer-assisted mapping was performed in all using either EnSite® (St Jude Medical Inc.) arrhythmia mapping and intra-cardiac catheter guidance system or CARTO™ (Biosense Webster Inc.) electroanatomical mapping systems. Ten patients (four males) with a median age of 39 plus or minus 8 years were studied. The total number of atrial tachyarrhythmias identified was 22 (six macro-reentrant, 16 micro-reentrant/focal). In nine patients, catheter ablation led to improvement in arrhythmia episodes and/or symptoms during follow-up of 41 plus or minus 20 months. Following ablation(s), five patients required pacing for pre-existing conduction disease and five needed further surgery for haemodynamic indications. All patients remained on anti-arrhythmic drugs.

CONCLUSIONS

Patients with surgically repaired tetralogy of Fallot and atrial tachyarrhythmias typically have multiple arrhythmic circuits/foci arising from a scarred right atrium. Catheter ablation reduces arrhythmia frequency and improves symptoms. However, hybrid management is often required, comprising drugs, pacing, and further surgery tailored to the individual.

Pulmonary valve replacement in adults with repaired tetralogy of Fallot

There is a growing population of young adults with tetralogy of Fallot. Although surgical approaches have evolved, many adults with repaired tetralogy of Fallot have been left with residual pulmonary regurgitation. Pulmonary regurgitation is an important contributor to a number of late complications including exercise limitations, right heart failure, arrhythmia, and sudden death. Because bioprosthetic valves are used in this population, clinicians must weigh the beneficial effects of pulmonary valve replacement against the associated risks, including subsequent re-operation. In this review, we will appraise the evidence supporting pulmonary valve replacement in the adult with repaired tetralogy of Fallot, as well as the optimal timing and mode of intervention.

Practical stepwise approach to rhythm disturbances in congenital heart diseases

Patients with congenital heart diseases (CHD) are confronted with early- and late-onset complications, such as conduction disorders, arrhythmias, myocardial dysfunction, altered coronary flow, and ischemia, throughout their lifetime despite successful hemodynamic and/or anatomical correction. Rhythm disturbance is a well-known and increasingly frequent cause of morbidity and mortality in patients with CHD. Predisposing factors to rhythm disturbances include underlying cardiac defects, hemodynamic changes as part of the natural history, surgical repair and related scarring, and residual hemodynamic abnormalities. Acquired factors such as aging, hypertension, diabetes, obesity, and others may also contribute to arrhythmogenesis in CHD. The first step in evaluating arrhythmias in CHD is to understand the complex anatomy and to find predisposing factors and hemodynamic abnormalities. A practical stepwise approach can lead to diagnosis and prompt appropriate interventions. Electrophysiological assessment and management should be done with integrated care of the underlying heart defects and hemodynamic abnormalities. Catheter ablation and arrhythmia surgery have been increasingly applied, showing increasing success rates with technological advancement despite complicated arrhythmia circuits in complex anatomy and the difficulty of access. Correction of residual hemodynamic abnormalities may be critical in the treatment of arrhythmia in patients with CHD.

Tetralogy of Fallot

Tetralogy of Fallot is the most common form of cyanotic congenital heart disease, and one of the first to be successfully repaired by congenital heart surgeons. Since the first procedures in the 1950s, advances in the diagnosis, perioperative and surgical treatment, and postoperative care have been such that almost all those born with tetralogy of Fallot can now expect to survive to adulthood. The startling improvement in outcomes for babies born with congenital heart disease in general-and for those with tetralogy of Fallot in particular-is one of the success stories of modern medicine. Indeed, in many countries adults with tetralogy of Fallot outnumber children. Consequently, new issues have emerged, ranging from hitherto unpredicted medical complications to issues with training for caregivers and resource allocation for this population of survivors. Therefore, evolution of treatment, recognition of late complications, research on disease mechanisms and therapies-with feedback to changes in care of affected children born nowadays-are templates on which the timely discussion of organisation of care of those affected by congenital heart diseases from the fetus to the elderly can be based. Here, we focus on new developments in the understanding of the causes, diagnosis, early treatment, and late outcomes of tetralogy of Fallot, emphasising the continuum of multidisciplinary care that is necessary for best possible lifelong treatment of the 1% of the population born with congenital heart diseases.

Effects of regional dysfunction and late gadolinium enhancement on global right ventricular function and exercise capacity in patients with repaired tetralogy of Fallot

BACKGROUND

The underlying mechanisms that contribute to global right ventricular (RV) dysfunction in patients with repaired tetralogy of Fallot are incompletely understood. We therefore sought to quantify regional RV abnormalities and to determine the relationship of these to global RV function and exercise capacity.

METHODS AND RESULTS

Clinical and cardiac magnetic resonance data from 62 consecutive patients with repaired tetralogy of Fallot were analyzed (median age at follow-up 23 years [limits 9 to 67 years]). Using cardiac magnetic resonance data, 3D RV endocardial surface models were reconstructed from segmented contours, and a correspondence between end diastole and end systole was computed with a novel algorithm. Regional RV abnormalities were quantified and expressed as segmental ejection fraction, spatial extent of dyskinetic area, displacement of dyskinetic area, and score of extent of late gadolinium enhancement. Regional abnormalities of function and hyperenhancement were greatest in the RV outflow tract (RVOT). These regional RVOT abnormalities correlated with global RV ejection fraction: RVOT ejection fraction r=0.64, P<0.0001; RVOT dyskinetic area r=-0.51, P<0.0001; RVOT displacement of dyskinetic area r=-0.49, P<0.0001; and RVOT late gadolinium enhancement score r=-0.33, P=0.01. Peak oxygen consumption during exercise correlated best with RVOT ejection fraction (r=0.56, P=0.0002) compared with the remainder of the RV (r=0.35, P=0.03). The only cardiac magnetic resonance variable independently predictive of aerobic capacity was RVOT ejection fraction (P=0.02).

CONCLUSIONS

A greater extent of regional abnormalities in the RVOT adversely affects global RV function and exercise capacity after tetralogy of Fallot repair. These regional measures may have important implications for patient management, including RVOT reconstruction, at the time of pulmonary valve replacement.

Catheter Ablation of Ventricular Tachycardia After Repair of Congenital Heart Disease

Background— Catheter ablation of ventricular tachycardia (VT) after repair of congenital heart disease can be difficult because of nonmappable VTs and complex anatomy. Insights into the relation between anatomic isthmuses identified by delineating unexcitable tissue using substrate mapping techniques and critical reentry circuit isthmuses might facilitate ablation.

Methods and Results— Sinus rhythm voltage mapping of the right ventricle was performed in 11 patients with sustained VT after repair of congenital heart disease. Unexcitable tissue from patch material, valve annulus, or dense fibrosis, identified from bipolar voltage (<0.5 mV) and pacing threshold (>10 mA), was defined as an anatomic isthmus boundary bordering 4 isthmuses between (1) the tricuspid annulus and scar/patch in the anterior right ventricular outflow, (2) the pulmonary annulus and right ventricular free wall scar/patch, (3) the pulmonary annulus and septal scar/patch, and (4) the septal scar/patch and tricuspid annulus. The reentry circuit isthmuses of all induced 15 VTs (mean cycle length, 276±78 ms; 73% poorly tolerated), identified by activation, entrainment, and/or pace mapping, were located in an anatomic isthmus (11 of 15 VTs in anatomic isthmus 1). Transecting the anatomic isthmuses by ablation lesions abolished all VTs. During 30.4±29.3 months of follow-up, 91% of patients remained free of VT.

Conclusions— Reentry circuit isthmuses in VT late after repair of congenital heart disease are located within anatomically defined isthmuses bordered by unexcitable tissue. The boundaries can be identified with 3-dimensional substrate mapping and connected by ablation lines during sinus rhythm. These findings should facilitate catheter and surgical ablation of stable and unstable VTs.

The impact of pulmonary valve replacement after tetralogy of Fallot repair: a matched comparison

OBJECTIVE

While there are no controlled studies, pulmonary valve replacement (PVR) after late tetralogy of Fallot repair is performed for patients with symptoms, arrhythmia or ventricular dysfunction. We sought to determine the impact of PVR on clinical outcomes.

METHODS

In a matched cohort study, 82 patients with PVR after tetralogy of Fallot repair without a history of ventricular arrhythmia were matched and compared with similarly followed non-PVR control subjects. A propensity-score adjusted analysis using repeated measures regression techniques was performed.

RESULTS

For the PVR subjects, the mean age was 28 years with a mean duration follow-up of 9 years. Before PVR, these subjects were significantly more likely than matched non-PVR subjects to have had non-ventricular arrhythmias, symptoms, lower functional class, longer QRS duration, lower right ventricular ejection fraction and higher right ventricular pressure, and reduced exercise duration but not aerobic capacity. During follow-up, sudden death occurred in four non-PVR subjects compared with no PVR subjects, with three episodes of ventricular tachycardia in the PVR subjects versus none in the non-PVR subjects (p=0.49). Symptoms and functional class improved in the PVR subjects with no change in the non-PVR subjects (p<0.001). The change in QRS duration was not significantly different between PVR and non-PVR subjects (p=0.48). Oxygen consumption at peak exercise did not significantly change in either group. For PVR subjects, there was a significant qualitative reduction in pulmonary (p<0.001) and tricuspid valve regurgitation (p=0.009) and right ventricular size (p<0.001) and dysfunction (p<0.001) noted on echocardiography.

CONCLUSIONS

Symptoms and functional status are improved after late PVR, with a reduction in pulmonary and tricuspid valve regurgitation and right ventricular size and dysfunction. While a significant impact on arrhythmia was not detected, there were no sudden deaths in the PVR subjects.

Usefulness of cardiopulmonary exercise to predict long-term prognosis in adults with repaired tetralogy of Fallot

Adults with tetralogy of Fallot (TOF) have increased long-term mortality. The identification of patients at greater risk for death or cardiac-related morbidity is challenging. This study was conducted to assess the prognostic value of cardiopulmonary exercise testing in adults with repaired TOF. One hundred eighteen consecutive adults with repaired TOF (mean age at repair 4.8 +/- 4.2 years) underwent cardiopulmonary exercise testing at a mean age of 24 +/- 8 years (range 16 to 59). The degree of pulmonary regurgitation, right ventricular function, and right ventricular systolic pressure were determined by transthoracic echocardiography. After the exercise tests, patients were regularly followed up for cardiac-related events. During a mean follow-up of 5.8 +/- 2.3 years (range 0.6 to 9.7), 9 patients died and 18 underwent hospitalization. Peak oxygen uptake (hazard ratio 0.974, 95% confidence interval 0.950 to 0.994), the slope of ventilation (VE) per unit of carbon dioxide production (VCO(2)) (hazard ratio 1.076, 95% confidence interval 1.038 to 1.115), and New York Heart Association functional class (hazard ratio 2.118, 95% confidence interval 1.344 to 3.542) were independent predictors of death or hospitalization. Patients with peak oxygen uptake < or =36% of predicted value and those with VE/VCO(2) slopes >39 were at greater risk for cardiac-related death (5-year mortality 48% vs 0%, p <0.0001, and 31% vs 0%, p <0.0001, respectively). In conclusion, the measurement of peak oxygen uptake and VE/VCO(2) slope in adults with repaired TOF can be prognostically important and could become a powerful tool to rationalize decisions regarding the prevention of premature sudden death and the need for reintervention.

Management after childhood repair of tetralogy of fallot

The four characteristic findings in tetralogy of Fallot (TOF) include the following: 1) a malaligned ventricular septal defect; 2) right ventricular outflow and/or pulmonary valve/artery stenosis or atresia; 3) a dextraposed overriding aorta; and 4) right ventricular hypertrophy. This article focuses solely on the outcomes and treatment of surgically corrected patients born with TOF. In the modern era, early surgical repair consisting of ventricular septal defect closure and alleviation of right ventricular outflow obstruction have gained favor over early palliation with an aortopulmonary shunt followed by intracardiac repair. Surgical outcomes are excellent and dramatically improve prognosis. However, these patients are not "cured" and are at significant risk of developing subsequent electrical and hemodynamic problems. An operated patient with TOF should be evaluated at regular intervals by a cardiologist trained in congenital heart disease; any symptoms suggestive of hemodynamic or electrical compromise should spur further investigation. Advances in imaging, medical therapy, electrophysiology, device/resynchronization therapy, and percutaneous intervention provide the clinician with a number of therapeutic options. Surgical techniques have changed significantly since the early intracardiac repairs of the 1960s and 1970s. The deleterious hemodynamic and electrical effects of pulmonary regurgitation and ventriculotomy scars have spurred efforts to ensure pulmonary valvular competence and minimize the extent of ventricular incisions. Since Blalock and Taussig's first palliative shunt in 1945, the survival and quality of life for patients with TOF has improved dramatically; this is one of the great accomplishments for cardiovascular medicine in the 20th century. The 21st century promises further success with the advent of a myriad of technologic advancements.

Surgery Insight: late complications following repair of tetralogy of Fallot and related surgical strategies for management

Biventricular correction of tetralogy of Fallot was devised more than 50 years ago. Current short-term outcomes are excellent. The potential for late complications is, however, an important concern for the growing number of postrepair survivors. Progressive pulmonary valve regurgitation leading to right heart failure and arrhythmia are centrally important problems faced by these patients. New techniques are, however, likely to change the future outcomes for postrepair survivors. These techniques include percutaneous valve replacement, arrhythmia ablation surgery, and strategies that emphasize preservation of the pulmonary valve even at the cost of leaving some residual valvular stenosis. The objectives of this Review are to outline the major complications that arise late after repair of tetralogy of Fallot, to describe the surgical approaches that have been developed to avoid and manage arising complications, and to briefly explore how novel treatment paradigms could change the future long-term outlook for patients following tetralogy repair.