A patient suffered from recurrent seizures during sleep and torsades de pointes with a QTc of 530 ms. Mutational analysis identified a N406K mutation in SCN5A.
Fetal rhythm phenotype and postnatal QTc can predict postnatal rhythm and suggest genotype: bradycardic fetuses usually have KCNQ1 mutation, while those with TdP and/or a postnatal QTc more than 500 ms have SCN5A, KCNH2 or uncharacterized mutations.
Four fetuses (2 KCNH2 and 2 SCN5A), all with corrected QT ≥ 620 ms, had frequent episodes of Torsade de Pointes, which were present 22-79% of the time.
We studied all LQT1 (n=10), LQT2 (n=34), and LQT3 (n=6) patients from 4 centers for whom ECGs of TdP onset were available and analyzed whether pauses preceded TdP onset (first available ECG per patient).
The cardiac sodium channel (SCN5A) mutation L1825P has been identified in a patient with drug-induced torsade de pointes precipitated by the IKr blocker cisapride.
High concentrations of intravenous nicorandil, a potassium channel opener, have been shown to be capable of decreasing QT and TDR, and preventing TdP in LQT1 and LQT2 but not in LQT3.
The cardiac sodium channel (SCN5A) mutation L1825P has been identified in a patient with drug-induced torsade de pointes precipitated by the IKr blocker cisapride.
The in vivo electrophysiologic mechanism of torsade de pointes in the long QT syndrome is described, using as a paradigm the anthopleurin-A canine model, a surrogate for LQT3.