**1. Introduction**

Heart failure in children is a growing global public health concern. In the United States, approximately 14,000 children are hospitalized for heart failure annually [1]. Symptoms of heart failure may include poor feeding, poor growth, and exercise intolerance. Heart failure in pediatric patients has various etiologies including failing physiology in congenital heart disease, inflammatory disease such as myocarditis, arrhythmia, post chemotherapy exposure, primary cardiomyopathy, and cardiac transplant rejection. Patients with congenital heart disease are at increased risk for developing heart failure secondary to chronic volume overload, elevated atrial and ventricular pressure, inadequate myocardial perfusion, and persistent ventricular dysfunction following surgical intervention. It has been reported that approximately 70% of hospital admissions for pediatric heart failure involve patients with congenital heart disease [1]. The risk for heart failure in congenital heart disease increases with age, with nearly 25% of adult congenital heart disease patients experiencing heart failure by the age of 30 years [2]. The Fontan palliation has been associated with high risk of developing heart failure with independent predictors of single morphological right ventricle, higher right atrial pressure, and evidence of protein-losing enteropathy [3].

Heart failure in children is associated with high morbidity and mortality with 20-fold increased risk of death during hospitalization [4, 5]. Noncardiac complications may include sepsis, renal failure, and respiratory failure. Studies have demonstrated that factors associated with increased risk of hospital mortality include acute renal failure and hepatic injury [1]. Early intervention with appropriate medical therapy is important in the management of acute heart failure. In cases where conventional therapies are not sufficient, mechanical circulatory support may be necessary.

Ventricular assist device (VAD) therapy has emerged as an important tool in the management of severe and refractory heart failure. An increasing number of patients are supported by a VAD, improving survival of patients whether used as destination therapy, bridge to transplantation, or bridge to cardiac function recovery. Over 25,000 VADs have been implanted in the United States [6] and the number of devices implanted in pediatric patients has increased over the years [7–9]. Cardiomyopathy, congenital heart disease, and myocarditis are the most frequently encountered underlying conditions in pediatric heart failure patients requiring VAD therapy [10, 11]. As there is increased risk for atrial and ventricular tachyarrhythmias in patients with heart failure, it is not uncommon to encounter these arrhythmias following VAD implantation.
