Jonathan N Johnson

Learn More
CONTEXT The efficacy of treatments for pediatric obesity remains unclear. OBJECTIVE We performed a systematic review of randomized trials to estimate the efficacy of nonsurgical interventions for pediatric obesity. DATA SOURCES Librarian-designed search strategies of nine electronic databases from inception until February 2006, review of reference lists(More)
BACKGROUND Long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT) are two of the most common, potentially lethal, cardiac channelopathies. Treatment strategies for the primary and secondary prevention of life-threatening polymorphic ventricular tachycardia/fibrillation include pharmacotherapy with beta-blockers, implantable(More)
Postural orthostatic tachycardia syndrome was defined in adult patients as an increase >30 beats per minute in heart rate of a symptomatic patient when moving from supine to upright position. Clinical signs may include postural tachycardia, headache, abdominal discomfort, dizziness/presyncope, nausea, and fatigue. The most common adolescent presentation(More)
CONTEXT The efficacy of lifestyle interventions to encourage healthy lifestyle behaviors to prevent pediatric obesity remains unclear. OBJECTIVE Our objective was to summarize evidence on the efficacy of interventions aimed at changing lifestyle behaviors (increased physical activity, decreased sedentary activity, increased healthy dietary habits, and(More)
Pulmonary function in older children and adolescents following surgical repair of congenital heart disease is often abnormal for various reasons. Many of these patients report symptoms of exercise intolerance although the reason(s) for this symptom can be complicated and sometimes interrelated. Is it simply deconditioning due to inactive lifestyle,(More)
BACKGROUND Long QT syndrome (LQTS) typically presents with syncope, seizures, or sudden death. Patients with LQTS have been misdiagnosed with a seizure disorder or epilepsy and treated with antiepileptic drug (AED) medication. The gene, KCNH2, responsible for type 2 LQTS (LQT2), was cloned originally from the hippocampus and encodes a potassium channel(More)
BACKGROUND The prevalence of atrial fibrillation (AF) in the young (age <50 years) is 0.1%, or 1:1,000 persons. Mutations in KCNQ1-, KCNH2-, and KCNA5-encoded potassium channels and SCN5A-encoded sodium channels have been reported in familial AF. A mechanism of atrial torsade has been suggested to occur in patients with congenital long QT syndrome (LQTS).(More)
BACKGROUND Long QT syndrome (LQTS) is a potentially lethal but highly treatable cardiac channelopathy. Treatment options include pharmacotherapy, device therapy, and left cardiac sympathetic denervation (LCSD). Here, we sought to determine the characteristics of LQTS patients who have had ≥1 LQTS-related breakthrough cardiac event (BCE) after LCSD. (More)
OBJECTIVES The purpose of this study was to compare the efficacy of beta-blockers in congenital long QT syndrome (LQTS). BACKGROUND Beta-blockers are the mainstay in managing LQTS. Studies comparing the efficacy of commonly used beta-blockers are lacking, and clinicians generally assume they are equally effective. METHODS Electrocardiographic and(More)
Congenital long QT syndrome (LQTS) affects an estimated 1 in 2500 people and typically presents with syncope, seizures or sudden death. Whereas someone exhibiting marked prolongation of the QT interval with QTc exceeding 500 ms who was just externally defibrillated from torsades de pointes while swimming poses negligible diagnostic challenge as to the(More)