Arrhythmias and sudden death among older children and young adults following tetralogy of Fallot repair in the current era: are previously reported risk factors still applicable?

BACKGROUND: Young adult patients (pts) with repaired tetralogy of Fallot (TOF) remain at risk for arrhythmias (Ar) and sudden cardiac death (SCD). Based on past studies with earlier pt subsets, Ar/SCD events were associated with right ventricular (RV) systolic pressures >60 mm Hg, outflow tract gradients >20 mm Hg, and QRS duration >180 ms. However, there are limited recent studies to evaluate these risk factors in the current patient generation. METHODS: Patients with TOF followed over the past 50 years were grouped by presence of any arrhythmias (group 1), absence of arrhythmias (group 2), and presence of SCD or significant ventricular arrhythmias (group 3) and correlated with current pt age, gender, age at repair, repair types, echocardiogram, cardiac magnetic resonance imaging, electrocardiogram/Holter, hemodynamics, and electrophysiology findings. RESULTS: Of 109 pts, 52 were male aged 17-58 years. Of these, 59 (54%) had Ar, two of whom had SCD. These 59 pts were chronologically older at the time of analysis, with repair at an older age and wider QRS duration (78-240, mean 158 ms) when compared with those without Ar. However, there was no correlation with surgical era, surgical repair, gender, RV pressure >60 mm Hg, right ventricular outflow tract gradient >20 mm Hg, or RV end-diastolic volume on CMRI. CONCLUSIONS: Ar/SCD risk continues to correlate with repair age and advancing pt age. QRS duration is longer in these patients but at a shorter interval (mean 158 ms) and less RV pressure (mean 43 mm Hg) than previously reported. In the current TOF patient generation, neither surgical era, type of repair, RV outflow gradient nor RV volume correlate with Ar/SCD. Electrophysiologic testing to verify and identify arrhythmias remains clinically effective.

Infants and children with tachycardia: natural history and drug administration.

Tachyarrhythmias can occur at any age from the developing fetus through adulthood. However, in deference to adult-onset ischemic cardiac issues, abnormal heart rhythms occurring in the young are often due to developmental alterations of the cardiac conduction tissue, genetically-inherited changes of myocardial cellular ion membrane properties and both pre- and post-surgical repair of associated structural congenital heart anatomical defects. And different from adults, abnormal rhythms occurring in the young can spontaneously disappear with progressive patient growth. Both supra- and ventricular tachyarrhythmias occur in the young although atrial rhythm abnormalities far exceed those of the ventricle. In both, pharmacologic therapies to alter tissue conduction and refractoriness remain the mainstay for initial intervention in the infant and young child, reserving more invasive and potentially harmful ablation therapies for drug-refractory cases. The purpose of the review is to present common and uncommon tachyarrhythmias which can occur in the fetus and throughout infancy. Emphasis will be placed on their electrocardiographic identification, recognition of any associated structural congenital heart defects and recommended pharmacologic management. Drug therapies will be divided according to mechanism of action and discussions of which particular agent is potentially best-suited to treat which specific tachyarrhythmia. A listing of current pharmacologic agents used in the young with appropriate dosages is included.

Superior vena cava and innominate vein dimensions in growing children : an aid for interventional devices and transvenous leads.

Transvenous (TV) pacing and defibrillation leads are frequently implanted in children as part of treatment for various congenital and acquired rhythm abnormalities. However, the lead-vascular endothelial interaction is not a benign process and is associated with a risk of progressive venous obstruction. Often, this obstruction requires surgical or interventional relief. The risk of obstruction is related to venous diameters at implant and lead size. Since venous diameters are largely unknown at different ages, the purpose of this study was to correlate innominate vein (INN) and superior vena cava (SVC) diameters with body dimensions in growing children.