It has new content on atrial fibrillation, implantable defibrillators, indications for pacemaker implantation, anticoagulant therapy, long QT syndromes
and other channelopathies, and recently-approved anti-arrhythmia drugs.
The congenital long QT syndromes from genotype to phenotype: clinical implications.
Long QT syndrome (LQTS) is an uncommon cardiac disorder of repolarisation leading to prolonged QT interval and T wave abnormalities in the ECG, thus predisposing to Torsades de Pointes (TdP).
An important cause of sudden death due to ventricular arrhythmias in apparently healthy people are the Long QT Syndromes
(LQTS), which are caused by genetic mutations either in the ion channels themselves or, in some cases, other cellular processes that directly or indirectly affect the membrane potential so as to prolong repolarization (9,10).
Long QT syndromes
are rare autosomal dominant inherited syndromes affecting approximately 1 in about 2500 individuals, and are produced by more than 400 different mutations (5,6).
In cases in which no structural heart disease can be identified, arrhythmias resulting from such disorders as the long QT syndromes
(LQTSs) are now commonly considered to be likely causes.
INTRODUCTION: The long QT syndrome
has aroused considerable interest in the medical community since its first description by Jervell-Lange in congenitally deaf children and later independently by Romano and Ward in persons with normal hearing.
It is a sub-variant of long QT syndrome
, which is a heart condition that causes cardiac muscle to take longer than usual to recharge between beats characterized by prolonged QT interval on an electrocardiograph (ECG) and associated with a high risk for syncope, fits and sudden death.
9) Acquired long QT syndrome
is most commonly caused by drug administration, typically that of antiarrhythmic drugs such as quinidine.
Mutations in the hminKgene cause long QT syndrome
and suppress IKs function.
Torsade de pointes is a form of polymorphic ventricular tachycardia that occurs in the setting of both congenital and acquired long QT syndrome
T wave morphology was defined as in the congenital Long QT syndrome
(LQTS): 1) "LQT1-like morphology" denoted a long QT interval (QTc interval [greater than or equal to] 450 ms) with broad T waves; 2) "LQT2-like morphology" denoted a long QT interval with double (notched) T waves; and 3) "LQT3-like morphology" denoted a long QT interval with small T waves separated from the (IRS interval by a long isoelectric ST-segment (12, 13).