title: [Long QT syndrome: a brief review of the electrocardiographical diagnosis including Viskin's test].
abstract: The QT interval measures both repolarization and depolarization. Learning to measure the QT interval and know how to correct (QTc) for heart rate (HR) is essential for the diagnosis of long QT syndrome (LQTS). The QTc interval changes in duration and even morphology depending on the time of the day and on a day-to-day basis. A diminished adaptive response of the QTc interval to changes in HR is known as QT hysteresis. Viskin has introduced a very simple clinical test to confirm the diagnosis of LQTS based on the "hypoadaptation" of the QT when standing. This phenomenon gives the appearance of a "stretching of the QT" on the surface ECG. Likewise, he has coined the term "QT stunning" to refer to the phenomenon that the QTc interval does not return to baseline despite recovery of baseline HR after standing. This article shows some examples of the Viskin's test.
authors.affiliation: Departamento de Electrocardiología, Instituto Nacional de Cardiología Ignacio Chávez, México D.F., México. manlio.marquez@gmail.com
authors.forename: Manlio F
authors.initials: MF
authors.lastname: Márquez
mesh_terms: D003935:Diagnostic Techniques, Cardiovascular; D004562:Electrocardiography / Q000379:methods; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis*