Humans ; Torsades de Pointes

Although amiodarone is generally regarded as safe with a low incidence of associated arrhythmias, torsade de pointes (TdP) has been observed usually in the presence of predisposing factors. We report a case of amiodarone-induced TdP after long-term administration of a low dose of oral amiodarone in the absence of predisposing factors.
Amiodarone ; Arrhythmias, Cardiac ; Incidence ; Torsades de Pointes

No abstract available.
Magnesium Sulfate* ; Magnesium* ; Torsades de Pointes*

Torsades de pointes (TdP) is a rare complication of a complete atrioventricular block with QT prolongation. Additional risk factors, such as hypokalemia, may increase the risk of TdP during atrioventricular (AV) block. We experienced a case of TdP, caused by a complete heart block and hypokalemia, which was successfully treated by implanting a permanent pacemaker and correction of the electrolyte imbalance.
Atrioventricular Block* ; Heart Block ; Hypokalemia* ; Risk Factors ; Torsades de Pointes*

No abstract available.
Humans ; Long QT Syndrome ; Postoperative Period ; Torsades de Pointes

Electrocardiography ; Female ; Humans ; Syncope/etiology* ; Torsades de Pointes/etiology*

Diagnosis, Differential ; Electrocardiography ; Humans ; Tachycardia, Ventricular ; Torsades de Pointes

OBJECTIVETo investigate the mechanism of drug-induced torsade de pointes (Tdp) in dogs.

METHODSIn arterially perfused canine left ventricular wedge preparations, the action potential duration (APD) of the endocardial (Endo), midmyocardial (M) and epicardial (Epi) myocytes, and transmural electrocardiogram (ECG) were recorded simultaneously. The effects of different concentrations of D-Sotalol on APD, transmural dispersion of repolarization (TDR), early after depolarization (EAD) and Tdp were observed.

RESULTSD-Sotalol prolonged APD of the Endo, M and Epi cells in a concentration-dependent manner from 0-100 µmol/L, and increased TDR due to a preferential APD prolongation of the M cells relative to Epi and Endo cells. The application of D-Sotalol elicited EAD, R on T ventricular premature beats, transmural reentry and Tdp in the M cells.

CONCLUSIONEAD and R on T ventricular premature beats induced by D-Sotalol in M cells triggers Tdp, which is maintained by TDR increment and transmural reentry.

Animals ; Dogs ; Electrocardiography ; Heart Conduction System ; Torsades de Pointes ; chemically induced ; physiopathology

BACKGROUNDTorsade de pointes (TdP) is a form of polymorphic ventricular tachycardia featuring prolonged QT intervals. Female gender is associated with an increased risk of TdP. However, the causes of the sex difference in risk are poorly understood. Recently, transmural dispersion of repolarization (TDR) has been implicated in the genesis of TdP. Consequently, we compared TdP incidence and TDR between male and female rabbit hearts in order to investigate the mechanism of sex difference in TdP risk in rabbits in vitro.

METHODSBy means of monophasic action potential recording techniques, the monophasic action potential of the epicardium, midmyocardium, and endocardium were simultaneously recorded using specially designed plunge-needle electrodes placed across the left ventricular free wall of both female (n = 8) and male (n = 8) rabbit hearts purfused by the Langendorff method. TdP was induced by bradycardia, d-sotalol, and low-K+, Mg2+ Tyrode solution.

RESULTSTDR measurements in all three myocardial layers of male and female rabbit hearts were (18 +/- 2) ms and (21 +/- 2) ms, respectively (n = 8, P > 0.05). After perfusion with d-sotalol, the 90% monophasic action potential duration was prolonged in both male and female rabbits. TDR in male and female rabbit hearts increased to (29 +/- 2) ms and (61 +/- 2) ms, respectively, a difference that is significant. Eight female rabbit hearts had early afterdepolarization and 7 of them developed TdP. Seven male rabbit hearts had early after depolarization, but only one of these hearts developed TdP.

CONCLUSIONGreater TDR may play an important role in the higher incidence of TdP in female rabbit hearts.

Action Potentials ; Animals ; Electrocardiography ; Female ; Male ; Rabbits ; Risk ; Sex Characteristics ; Sotalol ; Torsades de Pointes ; etiology ; physiopathology

BACKGROUND: Methadone is a synthetic opioid that is widely used for the treatment of chronic pain. The association between methadone treatment and QT interval prolongation or which can lead to torsades de pointes has been confirmed with larger studies on high dose methadone. The aim of this study was to determine the effect of methadone on the QTc interval in patients, whether the daily dose of methadone should be lower than what has been previously investigated. METHODS: A total of 130 patients were included, with 90 patients in the methadone group and 40 patients in the control group. For each ECG, heart rate, QT interval and corrected QT (QTc) interval were recorded. The patient demographics, methadone dose and serum level, duration of methadone use and past medical history were collected. RESULTS: The QTc interval was significantly longer in the treatment group than in the control group (443 +/- 30.0 ms versus 408 +/- 28.0 ms, respectively, P < 0.0001) and more patients in the treatment group had a QTc interval greater than 450 ms (36.7% versus 7.5%, respectively, P = 0.0005). The QTc interval was not associated with methadone dose P = 0.9278), serum level (P = 0.2256) or duration of treatment (P = 0.1822). CONCLUSIONS: This study has shown that methadone use is associated with longer QTc intervals, even among patients with daily doses of less than 80 mg. In this study, no correlation was found between QTc duration and methadone dose, serum levels or duration of use. However, the magnitude of the QTc interval was associated with female gender and the use of antidepressants.
Antidepressive Agents ; Chronic Pain ; Demography ; Electrocardiography ; Female ; Heart Rate ; Humans ; Methadone ; Retrospective Studies ; Torsades de Pointes