What is the definition or description of: long qt syndrome?

Sudden death...: Romano-ward, without congenital deafness and jervell-lange-nielsen, with deafness. Both refer to a delay in the repolarization time of the cardiac cycle, when there is a "vulnerable" period. The time between the q wave and the t wave. A premature beat, which are common, in this period can cause deadly arrhythmias, like torsades de pointes. Tdp occurs when heart rate increases, consult cardiolog.