Conduction disorders result in cardiac arrhythmias that may be fatal. 
Histiocytoid cardiomyopathy, Arrhythmogenic right ventricular dysplasia, 
Isolated noncompaction of the left ventricle, Long QT syndrome (LQTS) and 
Brugada syndrome, are all well described. Congenital short QT syndrome is a new 
familial primary electrical disease of the heart, which is characterized by 
abnormally short QT interval and paroxysmal atrial and ventricular 
tachyarrhythmias, including sudden cardiac death. An autosomal dominant mode of 
inheritance has been suggested. Catecholaminergic polymorphic ventricular 
tachycardia is an inherited disease and occurs in the absence of structural 
heart disease or known associated syndromes. Although the histological 
appearance of some of these disorders may be diagnostic, molecular analysis is 
necessary to define clearly the particular type of cardiomyopathy.