Utility of a Simplified Lidocaine and Potassium Infusion in Diagnosing Long QT Syndrome among Patients with Borderline QTc Interval Prolongation

摘要

Congenital long QT syndrome (LQTS) is caused by mutations in the cardiac Na or K channels that result in a prolonged QTc interval and increased QT dispersion. Na channel blockers and K can reverse the repolarization abnormalities in the Na channel variant (LQT3) and K channel variant (LQT1, LQT2), respectively. The phenotype of LQTS can be difficult to recognize, especially when the QTc interval is mildly prolonged. Additional noninvasive testing methods are needed to enhance the diagnosis of LQTS. This study compared the response of the QTc interval and QT dispersion to a sequential lidocaine/K infusion in LQTS patients with borderline QTc interval prolongation and control patients as a means of diagnosing LQTS.