BACKGROUND: The Htr3a antagonist, ondansetron, has been reported to prolong the QT interval and induce Torsades de pointes in the treatment of postoperative nausea and vomiting. To explore the mechanisms underlying these findings, we examined the effects of ondansetron on the mouse cardiac voltage-gated K⁺ (Kv) channel. METHODS AND RESULTS: Ondansetron increased QT intervals in late pregnant (LP) mice. We measured the Kv channels in freshly isolated left ventricular (LV) myocytes from non-pregnant (NP) and late pregnant (LP) mice, using patch-clamp electrophysiology. Ondansetron blocked Kv current at a dose of 50 µM, and reduced the amplitude of peak current densities in a dose-dependent manner (0, 1, 5, 50 µM), in LP but not in NP mice. In contrast, serotonin and the Htr3 agonist, m-CPBG, increased Kv current densities in NP, but not in LP mice. Interestingly, during pregnancy, serum serotonin levels were markedly increased, suggesting the saturation of the effect of serotonin. Immunostaning data showed that Kv4.3 protein and Htr3a co-localize at the membrane and t-tubule of cardiomyocytes. Moreover, Kv4.3 membrane trafficking was enhanced in response to Htr3a-mediated serotonin stimulation in NP, but not in LP mice. Membrane analysis showed that serotonin enhances Kv4.3 membrane trafficking in NP, but not LP mice. CONCLUSION: Ondansetron reduced Kv current densities, and reduced the Kv4.3 membrane trafficking in LP mouse ventricular cardiomyocytes. This data suggests that QT prolongation by ondansetron is mediated by the reduction of Kv current densities and Kv4.3 membrane trafficking.
Animals ; Electrophysiology ; Membranes ; Mice* ; Muscle Cells* ; Myocytes, Cardiac ; Ondansetron* ; Postoperative Nausea and Vomiting ; Pregnancy ; Serotonin ; Torsades de Pointes

53-year-old female was admitted to our institution with alternating atrial flutter and junctional bradycardia. The patient had undergone the Warden procedure to correct sinus venosus type atrial septal defect combined with partial anomalous pulmonary venous return, and ring tricuspid annuloplasty for severe tricuspid regurgitation. She also had persistent left superior vena cava (PLSVC). With the assistance of a 3D electroanatomic mapping system, catheter ablation therapy was used successfully to treat atrial flutter associated with a channel in the right atrial scar, and a pacemaker was implanted through the PLSVC because of resulting symptomatic bradycardia.
Atrial Flutter ; Bradycardia* ; Cardiac Surgical Procedures ; Catheter Ablation ; Cicatrix ; Female ; Heart Defects, Congenital ; Heart Septal Defects, Atrial ; Humans ; Middle Aged ; Pacemaker, Artificial ; Scimitar Syndrome ; Tachycardia* ; Tricuspid Valve Insufficiency ; Vena Cava, Superior*

The delivery of single His-refractory ventricular extra-stimulus during supraventricular tachycardia is useful to identify the mechanism of the tachycardia. We present the different responses based on the ventricular extra-stimulus site. Our findings demonstrate that the atrial activation via an accessory pathway was not advanced based on the ventricular pacing site. Therefore, atrioventricular tachycardia could masquerade as atrioventricular nodal reentrant tachycardia.
Tachycardia ; Tachycardia, Atrioventricular Nodal Reentry ; Tachycardia, Supraventricular*

We report the case of a 19-year-old male who successfully recovered from sudden cardiac arrest. Careful evaluation did not reveal any electrical or structural abnormalities. He underwent implantable cardioverter defibrillator (ICD) implantation, with a diagnosis of idiopathic ventricular fibrillation (VF). Three months later, VF recurred and was successfully terminated by ICD shock. Electrocardiogram (ECG) revealed a slurred type J point elevation at the inferolateral leads with a horizontal/descending ST segment change, which was not present during the initial hospitalization. Cilostazol was prescribed to prevent further lethal ventricular arrhythmias. Subsequently, no arrhythmic events were reported, and the J wave disappeared at the follow-up ECG. However, recurrent VF episodes with an interval of 1–2 weeks occurred 1 year later, and were terminated by ICD shock. Simultaneous ECG revealed a J point elevation at the inferolateral leads. Cilostazol was replaced by quinidine. Subsequently, no arrhythmic event recurred for over 12 months. Serial follow-up ECG is needed to identify masked inherited primary arrhythmic syndromes in sudden cardiac arrest survivors diagnosed with idiopathic VF. Cilostazol and quinidine might be good therapeutic options to prevent further lethal events in cases where the J wave syndrome is present with recurrent ventricular arrhythmias.
Anti-Arrhythmia Agents ; Arrhythmias, Cardiac ; Death, Sudden, Cardiac* ; Defibrillators ; Diagnosis ; Electrocardiography ; Follow-Up Studies ; Heart Arrest ; Hospitalization ; Humans ; Male ; Masks ; Quinidine ; Shock ; Survivors ; Ventricular Fibrillation ; Young Adult

No abstract available.
Atrial Fibrillation* ; Humans

Anticoagulation therapy is widely used to prevent thromboembolism in patients with atrial fibrillation, venous thromboembolism, and mechanical heart valves. The temporary interruption of anticoagulants is common to reduce the bleeding risk during peri-procedures. Traditionally, warfarin was held for several days before procedures with heparin bridging therapy. However, recent data showed that stopping warfarin was not necessary before procedures with a low bleeding risk, such as a gastrointestinal endoscopy, cataract eye surgery, and dental procedures when the thromboembolic risk of the patient is moderate-to-high. This review article outlines the estimation of the thromboembolic and bleeding risk before procedures, and determines the timing of anticoagulant interruption.
Anticoagulants ; Atrial Fibrillation ; Cataract ; Endoscopy ; Endoscopy, Gastrointestinal ; Heart Valves ; Hemorrhage ; Heparin ; Humans ; Thromboembolism ; Tooth Extraction ; Venous Thromboembolism ; Warfarin

Cardioversion increases the risk for stroke or systemic embolic events, and patients scheduled for cardioversions need several weeks of anticoagulant treatment to prevent these adverse events. Anticoagulant therapy should be considered as a balancing act between the risk of stroke and the risk of life-threatening bleeding. The efficacy of non-vitamin K antagonist oral anticoagulants (NOACs) was found to be equal to, or even superior, to warfarin for the prevention of stroke, systemic embolism, and other outcomes in patients with atrial fibrillation, when all risk factors were considered. There have been few studies independently looking at the efficacy and safety profile of NOACs in cardioversion. The efficacy of both rivaroxaban and dabigatran in preventing stroke or major systemic embolic events post-cardioversion was found to be similar to that of warfarin. The efficacy of apixaban could not be compared based on the available data because of the limited number of procedures performed. However, all three NOACs were found to be safe for use in cardioversion when compared to warfarin.
Anticoagulants ; Atrial Fibrillation ; Dabigatran ; Electric Countershock* ; Embolism ; Hemorrhage ; Humans ; Risk Factors ; Rivaroxaban ; Stroke ; Warfarin

Atrial fibrillation (AF) can occur in acute coronary syndrome (ACS), which is a serious medical condition and may require the use of antiplatelet agents in addition to anticoagulants for stroke prevention. Recently, novel or non-vitamin K antagonist oral anticoagulants (NOACs) have been increasingly used for stroke prevention in patients with AF instead of traditional OACs. The duration of treatment or treatment with a stepwise approach (e.g. triple, double, or monotherapy) is determined depending on the clinical setting and the balance between the risks of ischemic stroke and bleeding. However, some concerns and controversies in the use of NOACs in patients with AF and ACS need to be addressed. Here, the current management for NOAC therapy in patients with ACS and AF will be reviewed based on recently published guidelines.
Acute Coronary Syndrome ; Anticoagulants ; Atrial Fibrillation ; Hemorrhage ; Humans ; Platelet Aggregation Inhibitors ; Stroke

The results of trials using novel or non-vitamin K-dependent new oral anticoagulants (NOACs) in the treatment of venous thromboembolism (VTE) reveal that these agents are non-inferior (in terms of efficacy) and possibly safer (particularly in terms of major bleeding) than the standard heparin/vitamin K antagonist (VKA) regimen. High TTR values were achieved under VKA treatment in all trials; however, it should be noted that the study populations comprised relatively young patients, very few of whom had cancer. At present, NOACs can be viewed as an alternative to standard treatment. Currently, experience with NOACs is limited, but continues to be accumulated. Practical recommendations for the use of NOACs in different clinical scenarios and the management of their bleeding complications are needed. The results of the trials using NOACs in the extended treatment of VTE are in line with those of the studies that tested these agents for acute-phase treatment and standard duration of anticoagulation after pulmonary embolism (PE) or VTE. They indicate that NOACs are both, effective (in terms of prevention of symptomatic or fatal recurrence of VTE) and safe (particularly in terms of major bleeding), probably safer than standard VKA regimens.
Anticoagulants ; Hemorrhage ; Humans ; Pulmonary Embolism ; Recurrence ; Venous Thromboembolism*

Anticoagulation treatment, including novel or non-vitamin K-dependent antagonist oral anticoagulants (NOACs), is essential to prevent thromboembolic events in high-risk atrial fibrillation patients. There are not enough studies on the effect and safety of NOACs in Asians. Due to the low body surface area, genetic polymorphism, and herbal diet of Asians, it is difficult to attain optimal anticoagulation with traditional anticoagulation treatment using vitamin K antagonists, and more bleeding complications are reported with this treatment. In several recent studies, the use of NOACs in Asians resulted in lower thrombo- embolic events and fewer bleeding complications than those with a vitamin K antagonist. Given the race-related differences of Asians, NOACs have sufficient efficacy and safety for the prevention of thromboembolic events in patients with atrial fibrillation.
Anticoagulants ; Asian Continental Ancestry Group* ; Atrial Fibrillation ; Body Surface Area ; Diet ; Embolism ; Hemorrhage ; Humans ; Polymorphism, Genetic ; Stroke ; Vitamin K