Anemia ; complications ; Hematologic Diseases ; complications ; Humans ; Long QT Syndrome ; etiology

Long QT interval is an important finding that is often missed by electrocardiogram interpreters. Long QT syndrome (inherited and acquired) is a potentially lethal cardiac channelopathy that is frequently mistaken for epilepsy. We present a case of long QT syndrome with multiple cardiac arrests presenting as syncope and seizures. The long QTc interval was aggravated by hypomagnesaemia and drugs, including clarithromycin and levofloxacin. Multiple drugs can cause prolongation of the QT interval, and all physicians should bear this in mind when prescribing these drugs.
Adult ; Defibrillators, Implantable ; Electrocardiography ; Heart Rate ; Humans ; Long QT Syndrome ; complications ; congenital ; diagnosis ; therapy ; Male ; Risk Factors ; Seizures ; complications

Abnormal enhanced transmural dispersion of repolarization (TDR) plays an important role in the maintaining of the severe ventricular arrhythmias such as torsades de pointes (TDP) which can be induced in long-QT (LQT) syndrome. Taking advantage of an in vitro rabbit model of LQT2, we detected the effects of KN-93, a CaM-dependent kinase (CaMK) II inhibitor on repolarization heterogeneity of ventricular myocardium. Using the monophasic action potential recording technique, the action potentials of epicardium and endocardium were recorded in rabbit cardiac wedge infused with hypokalemic, hypomagnesaemic Tyrode's solution. At a basic length (BCL) of 2000 ms, LQT2 model was successfully mimicked with the perfusion of 0.5 μmol/L E-4031, QT intervals and the interval from the peak of T wave to the end of T wave (Tp-e) were prolonged, and Tp-e/QT increased. Besides, TDR was increased and the occurrence rate of arrhythmias like EAD, R-on-T extrasystole, and TDP increased under the above condition. Pretreatment with KN-93 (0.5 μmol/L) could inhibit EAD, R-on-T extrasystole, and TDP induced by E-4031 without affecting QT interval, Tp-e, and Tp-e/QT. This study demonstrated KN-93, a CaMKII inhibitor, can inhibit EADs which are the triggers of TDP, resulting in the suppression of TDP induced by LQT2 without affecting TDR.
Action Potentials ; drug effects ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Arrhythmias, Cardiac ; etiology ; physiopathology ; prevention & control ; Benzylamines ; pharmacology ; Calcium-Calmodulin-Dependent Protein Kinase Type 2 ; antagonists & inhibitors ; metabolism ; Electrocardiography ; Electrophysiologic Techniques, Cardiac ; Endocardium ; drug effects ; physiopathology ; Heart ; drug effects ; physiopathology ; In Vitro Techniques ; Long QT Syndrome ; complications ; Pericardium ; drug effects ; physiopathology ; Piperidines ; pharmacology ; Protein Kinase Inhibitors ; pharmacology ; Pyridines ; pharmacology ; Rabbits ; Sulfonamides ; pharmacology ; Torsades de Pointes ; etiology ; physiopathology ; prevention & control

Long QT syndrome is associated with lethal tachyarrhythmia that can lead to syncope, seizure, and sudden death. Congenital long QT syndrome is a genetic disorder, characterized by delayed cardiac repolarization and prolongation of the QT interval on the electrocardiogram (ECG). Type 2 congenital long QT is linked to mutations in the human ether a go-go-related gene (HERG). There are environmental triggers of adverse cardiac events such as emotional and acoustic stimuli, but fever can also be a potential trigger of life-threatening arrhythmias in long QT syndrome type 2 patients. Herein, we report a healthy young man who experienced fever-induced polymorphic ventricular tachycardia and QT interval prolongation.
Adult ; Electrocardiography ; Fever/*complications ; Humans ; Long QT Syndrome/*diagnosis/*etiology ; Male ; Ventricular Fibrillation/*diagnosis/*etiology

Prolongation of QTc interval associated with Takotsubo cardiomyopathy (TC) has previously been reported in published case series. We report an unusual case of a patient who presented with TC associated with long-QT syndrome and developed cardiac arrest secondary to torsade de pointes. Since QT prolongation and bradycardia persisted after the resolution of TC, the patient received permanent pacemaker. Since then additional event did not occur. QT prolongation and bradycardia could be persistent even after recovery of TC, and permanent pacemaker insertion may be a treatment option of long QT syndrome related with TC.
Aged ; Bradycardia/diagnosis/therapy ; Cardiac Pacing, Artificial ; Coronary Angiography ; Diagnosis, Differential ; Electrocardiography ; Female ; Heart Arrest/diagnosis/etiology ; Humans ; Long QT Syndrome/*diagnosis/etiology ; Takotsubo Cardiomyopathy/complications/*diagnosis/ultrasonography ; Torsades de Pointes/*diagnosis/etiology

OBJECTIVETo summarize the clinical characteristics and outcome of patients with long-QT syndrome (LQTs) accompanied with torsade de pointes.

METHODSThirty-two eligible patients were included in this study. Clinical and electrocardiographic data were analyzed and telephone or out-patient follow-up were made in all patients.

RESULTSThere were 15 patients with inherited LQTs (h-LQTs) and 17 patients with acquired LQTs (a-LQTs). There are more women (n = 24) than men (n = 8). β blockers, potassium and magnesium supplement were the basic therapy for h-LQTs patients, bivent pacemaker was implanted in 2 patients and implantable cardioverter defibrillator was implanted in 5 patients. Ventricular tachyarrhythmias and syncope occurred in 4 patients during (39.4 ± 25.1) months follow-up. In 17 a-LQTs patients, one patient with dilated cardiomyopathy died suddenly and another patient with implanted cardioverter defibrillator experienced one ventricular tachycardia during (30.9 ± 13.3) months follow-up.

CONCLUSIONSThe prognosis in h-LQTs and a-LQTs patients with structure heart disease is poor. ICD or CRT-D therapy is suggestive for a-LQTs patients with structure heart disease.

Adolescent ; Adult ; Aged ; Female ; Follow-Up Studies ; Humans ; Long QT Syndrome ; complications ; therapy ; Male ; Middle Aged ; Pacemaker, Artificial ; Torsades de Pointes ; complications ; therapy ; Treatment Outcome ; Young Adult

OBJECTIVERisk factors, ECG characteristics and treatment options of patients with Torsade de Points associated with acquired QT prolongation are summarized in this study.

METHODUsing "torsade de points" and "QT prolongation" as the keywords to search the inpatients database from 1990 - 2010 of Fuwai hospital, 52 eligible patients were included in this analysis.

RESULTSStructural heart diseases were found in 67.3% and electrolyte disorders in 59.6% patients, 36.5% patients received diuretic therapy and 28.8% received antiarrhythmic drugs which might induce prolonged QT interval. The mean QTc was (571 ± 93) ms and (456 ± 50) ms before and after treatment. All patients received potassium and magnesium supplement. Isoproterenol was used in 32.7% patients. 13.5% patients received temporary pacing therapy.

CONCLUSIONSTorsade de points and acquired QT interval prolongation was often associated with electrolyte disorders and drugs causing QT prolongation. ECG and QTc should be intensively monitored for high risk patients. Early awareness of the warning signs might contribute to early recognition and proper treatment of patients with Torsade de Points associated with acquired QT prolongation.

Adult ; Female ; Humans ; Long QT Syndrome ; complications ; diagnosis ; therapy ; Male ; Middle Aged ; Risk Factors ; Torsades de Pointes ; complications ; diagnosis ; therapy

Heart ; physiopathology ; Humans ; Infant, Newborn ; Long QT Syndrome ; complications ; Male ; Tachycardia, Ventricular ; complications ; Torsades de Pointes ; complications

Adolescent ; Anesthesia ; methods ; Electrocardiography ; Humans ; Hypokalemia ; complications ; physiopathology ; Long QT Syndrome ; etiology ; Male ; Propofol ; adverse effects ; Ventricular Fibrillation ; chemically induced ; physiopathology

To explore the cellular mechanism responsible for the gender-related differences of ventricular tachyarrhythmias in long QT syndromes (LQTS), we observed the characteristics of pre-existing electrophysiological heterogeneity and dynamics of ventricular repolarization in different gender of LQT2 rabbit models. The intracellular floating microelectrodes technique was used to record transmembrane action potentials simultaneously from epicardial and endocardial sites of the arterially perfused rabbit left ventricular wedge preparation; in the mean time, the electrocardiogram (ECG) was also recorded. The wedge preparations were placed in a small tissue bath and arterially perfused with normal Tyrode's solution (control group), 100 mumol/L dl-sotalol Tyrode's solution (LQT2 model group), and 100 mumol/L dl-sotalol plus 3.0 mmol/L KCl Tyrode's solution (LQT2 model plus hypokalemia group), buffered with 95% O2 and 5% CO2 [(36.0+/-1) degrees C]. Double diastolic threshold currents were delivered with basic cycle length (BCL) 2 000, 1 000 and 500 ms (S1), respectively, to record transmembrane action potentials and transmural ECG. Each driving train of S1 is with 20 beats. To determine action potential duration restitution (APDR) curves, the S1-S2 programmed stimuli were used. The tissue was paced at 1 000 ms and 500 ms cycle length (S1) for eight beats, followed by a single premature stimulus (S2). The S1-S2 coupling interval was progressively shortened with 10 ms decrements until the S2 failed to capture. The results showed that female rabbits exhibited significantly longer transmural dispersion of repolarization (TDR) and steeper maximal slopes of APDR curves than that in male rabbits at same pacing rates (P<0.05), and which were pacing rate-dependent. In the condition of dl-sotalol plus hypokalemia, the TDR and the maximal slopes of APDR curves were significantly increased in comparison with that in the control group (P<0.01). At a BCL of 1 000 ms of seven experiments, one female showed torsade de pointes (TdP) in the LQT2 model group; five females and two males showed TdP in LQT2 model plus hypokalemia group, showing significant gender-related differences (P<0.05). The present findings suggest that the pre-existing electrophysiological and dynamic heterogeneity in the LQT2 model shows an obvious gender-related difference and pacing rate-dependence. Both increased TDR and steepness of APDR in female rabbits are possibly the major factors which prompt the TdP generation in female LQT2 rabbits more easily than in male rabbits.
Action Potentials ; physiology ; Animals ; Electrocardiography ; Female ; Long QT Syndrome ; complications ; physiopathology ; Male ; Rabbits ; Sex Factors ; Torsades de Pointes ; etiology ; physiopathology ; Ventricular Function ; physiology