Induction of TU abnormalities in patients with torsades de pointes

1. TU abnormalities could be induced by the specific interventions in the majority of the patients with TDP in chronic stage: isoproterenol in congenital long QT patients, disopyramide in Ia-related TDP patients, and slow heart rate in bradycardia-related TDP patients. 2. Humps in MAP could be recorded in all patients with congenital long QT syndrome by isoproterenol, in half of the patients with Ia-related TDP by disopyramide, but in none of the control patients by these agents. 3. The results suggested that TU abnormalities and the occurrence of hump in MAP were hypersensitive reactions. 4. The results also suggested that specific intervention was not enough for the appearance of marked TU abnormalities in some TDP patients, especially in Ia-related TDP patients. Additional aggravating factors were probably required for marked TU abnormalities and the occurrence of TDP in these patients.