Hot Topics in Tetralogy of Fallot

Abstract

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. We explore "hot topics" to highlight areas of emerging science for clinicians and scientists in moving toward a better understanding of the long-term management of patients with repaired TOF. From a genetic perspective, the etiology of TOF is multifactorial, with a familial recurrence risk of 3%. Cardiac magnetic resonance is the gold standard assessment tool based on its superior imaging of the right ventricular (RV) outflow tract, pulmonary arteries, aorta, and aortopulmonary collaterals, and on its ability to quantify biventricular size and function, pulmonary regurgitation (PR), and myocardial viability. Atrial re-entrant tachycardia will develop in more than 30% of patients, and high-grade ventricular arrhythmias will be seen in about 10% of patients. The overall incidence of sudden cardiac death is estimated at 0.2%/yr. Risk stratification, even with electrophysiologic testing and cardiac magnetic resonance, remains imperfect. Drug therapy has largely been abandoned, and defibrillator placement, despite its high risks for complications and inappropriate discharges, is often recommended for patients at higher risk. Definitive information about optimal surgical strategies for primary repair to preserve RV function, reduce arrhythmia, and optimize functional status is lacking. Post-operative lesions are often amenable to transcatheter intervention. In selected cases, PR may be treated with transcatheter valve insertion. Ongoing surveillance of RV function is a crucial component of clinical assessment. Except for resynchronization with biventricular pacing, no medical therapies have been shown to be effective after RV dysfunction occurs. In patients with significant PR with RV dilation, optimal timing of pulmonary valve replacement remains uncertain, although accepted criteria are emerging.

The burden of Fallot’s tetralogy among Nigerian children

“…Chromosomal abnormalities occur in up to 25% of patients with TOF (4). Some of those includes trisomies 13, 18 and 21 and 22q11.2 deletion syndrome (1,3,4). Trisomy 21 and 22q11.2 are the most common abnormalities (3).…”

Management of right ventricular outfl ow tract obstruction: Evolution to revolution

“…(14)(15)(16)(17)(18) Dysrhythmias are common in patients with PR and consist of atrial tachyarrhythmias in up to 30% and high grade ventricular tachycardias in 5 -10% of patients. (16,19) Gatzoulis identified a prolonged QRS ≥180ms as a risk factor for ventricular tachycardia and sudden death. (20) Additional problems include cardiac failure and right heart dilation in up to 29% of patients with isolated PR.…”

Heterogeneity of Ventricular Sympathetic Nervous Activity is Associated with Clinically Relevant Ventricular Arrhythmia in Postoperative Patients with Tetralogy of Fallot

“…Many studies have been conducted to identify RVA-related factors in postoperative TOF patients [2,6,7,23,26,28]. In addition to these traditional variables, such as resting ECG findings, the CTR, and RV function, we evaluated the association between ventricular SNA and RVA.…”

“…In postoperative TOF patients, greater QTD combined with a prolonged QRS is also associated with VT [7]. In fact, a prolonged QRS duration, especially C180 ms, and a large RV volume with reduced ventricular function are important predictors for RVA [28]. However, we found only one patient with a Values are mean ± SD or number BNP brain natriuretic peptide, Cath catheterization, CTR cardiothoracic ratio, ECG electrocardiogram, HMR heart-to-mediastinum ratio, LVEDP end-diastolic pressure of the left ventricle, LVEDVI end-diastolic volume index of the left ventricle, LVEF ejection fraction of the left ventricle, PR pulmonary regurgitation, QTc QT interval corrected for heart rate, QTD QT dispersion, RVA relevant ventricular arrhythmia, RVEDP enddiastolic pressure of the right ventricle, RVEDVI end-diastolic volume index of the right ventricle, RVEF ejection fraction of the right ventricle, RVP/LVP ratio of right ventricular systolic pressure to left ventricular systolic pressure, SNA sympathetic nervous activity, TR tricuspid regurgitation, WR washout ratio QRS duration C180 ms in the RVA group, and there was no significant association between abnormal RV function and RVA in our cohort (Table 3).…”