Approach to Ventricular Arrhythmias in the Pediatric Intensive Care Unit

Ventricular arrhythmia was once regarded uncommon in infants and children, since most cardiac arrests were thought to be hypoxia-induced bradycardia followed by asystole. Furthermore, ischemic heart disease, the basis for many of the ventricular arrhythmias in adults, is rare in pediatric patients. However, with the advent of pediatric critical care, improved techniques of extracorporeal life support, increasing awareness of genetic abnormalities, and a growing population of patients with congenital heart diseases, ventricular arrhythmia is being recognized more frequently in pediatric patients, and is becoming a larger management issue. Pediatric critical care is a special field that rapid diagnosis and intervention are often essential. These interventions may be life-saving or sometimes debilitating, depending on their appropriateness and timeliness. The spectrum of cardiac arrhythmias in the pediatric intensive care unit (PICU) ranges from those that are immediately life threatening to those with little or no hemodynamic consequences. However, patients in the PICU often have hemodynamic instability, poor cardiac reserve or structural cardiac defects so that they are especially vulnerable to arrhythmia-induced cardiac dysfunction. Therefore, early recognition and prompt management of life-threatening ventricular arrhythmias are essential aspects of the care that must be provided to these patients. Indeed, given with the heterogeneity of diseases and complexity of structural heart defects in the pediatric critical care setting, treatment must frequently be provided in the PICU even before the specific cardiac diagnosis is made. To meet this challenge, the management of life-threatening ventricular arrhythmias in children will be the most effective if these arrhythmias are anticipated by the pediatric intensivist. The aims of this chapter are to provide an update, from the standpoint of pediatric critical care, regarding comprehensive concepts of (1) non-cardiac clinical entities associated with ventricular arrhythmias, such as electrolyte imbalance, hypothermia, infection and drugs; (2) cardiac entities associated with ventricular arrhythmias, such as dilated cardiomyopathy, hypertrophic obstructive cardiomyopathy, and congenital heart diseases post cardiac surgery;