Weigh gain as a cause of ineffective drug therapy and failed subcutaneous defibrillator shocks in a pediatric patient with Jervell-Lange-Nielsen syndrome – A case report

Abstract Background Jervell and Lange-Nielsen syndrome (JLNS) is a rare inherited disorder characterized by congenital bilateral sensorineural deafness and a prolonged QT interval, predisposing to life-threatening arrhythmias. This case illustrates the challenges in the management of a pediatric patient with JLNS, highlighting the impact of weight gain on beta-blocker dosing and subcutaneous implantable cardioverter-defibrillator (S-ICD) efficacy. Case summary A 13-year-old male with a history of severe sensorineural hearing loss, recurrent emotion-triggered seizures, and JLNS diagnosed at age 4, presented with syncope and received three ICD shocks for ventricular fibrillation (VF). His weight gain (from 60 kg to 79 kg, with a BMI increase from 26.5 to 31.5) resulted in a dose reduction of nadolol to ∼1 mg/kg/day before subsequent dose increase according to body weight gain and failure of the device to deliver effective shocks. Shock impedance was significantly elevated due to increased subcutaneous fat and suboptimal lead positioning. After repositioning the S-ICD lead to a juxta-sternal position, shock impedance improved (85 Ohms), and the patient remained arrhythmia-free after one year of follow-up. Conclusion Effective management of LQTS requires diligent monitoring of weight, device function, and pharmacological dosing, which is particulary crucial in patients with JLNS. In pediatric patients, rapid weight gain can lead to both underdosing of beta-blockers and mechanical failures of ICD systems. Lifestyle modifications, including regular exercise and a heart-healthy diet, are crucial to prevent obesity and optimize long-term outcomes.