No abstract available.

The most important and widely-prescribed drug for anticoagulation is a vitamin K antagonist such as warfarin although it has several limitations in clinical use. New oral anticoagulants (NOACs) have been developed to overcome these problems. The clinical efficacy and safety of dabigatran, rivaroxaban, and apixaban have been shown to be superior to warfarin through large-scale clinical trials. These NOACs can replace warfarin in significant proportions of patients with non-valvular atrial fibrillation to prevent stroke. Recent management guidelines for atrial fibrillation have already recommended NOACs for stroke prevention instead of warfarin. Future clinical studies should resolve the limitations of NOACs and try to extend their clinical indications.
Anticoagulants ; Atrial Fibrillation ; Benzimidazoles ; beta-Alanine ; Dabigatran ; Humans ; Morpholines ; Pyrazoles ; Pyridones ; Rivaroxaban ; Stroke ; Thiophenes ; Vitamin K ; Warfarin

Catheter ablation is one of the major treatment options for patients with arrhythmia. It has been widely used since radiofrequency energy was adopted as a power source. Technical progress has resulted in better outcomes, better efficiency, and safer procedures. However, mechanisms of some forms of arrhythmia such as atrial fibrillation have not been fully elucidated in order to obtain a more favorable success rate. Therefore, progress in the basic research field to understand the mechanisms and substrates of arrhythmia as well as technical progress is essential for overcoming current obstacles in this therapeutic method.
Arrhythmias, Cardiac ; Atrial Fibrillation ; Catheter Ablation* ; Catheters* ; Electric Power Supplies ; Humans ; Tachycardia* ; Tachycardia, Supraventricular ; Tachycardia, Ventricular

Atrial fibrillation is the most common and most complex sustained arrhythmia. However, its pathophysiology has not been completely elucidated, therefore various approaches have been applied to its therapeutics. The management including pharmacological treatment is still evolving, and guidelines of atrial fibrillation have been updated frequently. This review article will introduce the principles and practical information on the pharmacological management in patients with atrial fibrillation based on the recently updated guidelines.
Arrhythmias, Cardiac ; Atrial Fibrillation ; Humans

Reynolds D, Duray GZ, Omar R, Soejima K, Neuzil P, Zhang S, Narasimhan C, Steinwender C, Brugada J, Lloyd M, Roberts PR, Sagi V, Hummel J, Bongiorni MG, Knops RE, Ellis CR, Gornick CC, Bernabei MA, Laager V, Stromberg K, Williams ER, Hudnall JH, Ritter P; Micra Transcatheter Pacing Study Group.

BACKGROUND AND OBJECTIVES: Major epicardial fat pads contain cardiac ganglionated plexi (GP) of the autonomic nervous system. Autonomic denervation may improve the success rate of atrial fibrillation (AF) ablation. This study was designed to elucidate the acute effects of blocking the right atrium-pulmonary vein (RA-PV) and left atrium-inferior vena cava (LA-IVC) fat pads on the electrophysiologic characteristics of the atrium and AF inducibility with a botulinum toxin injection. Materials and Methods: Eight mongrel dogs were studied. The RA-PV and LA-IVC fat pads were exposed through a median thoracotomy. Botulinum toxin (BT, 50 U to each fat pad, n=6) or normal saline (NS, n=2) was injected in the entire area of two fat pads. The study protocol was applied before injection and repeated at 1, 2, 3, 4, and 5 hours thereafter. The sinus rate, ventricular rate during rapid atrial pacing with a cycle length of 50 ms, and AF inducibility were measured with and without vagal stimulation (VS). Bilateral cervical VS was applied (20 Hz, 0.2 ms, 5.6+/-2.0 V). AF inducibility was evaluated with burst pacing with 200 impulses at a 50-ms cycle length. RESULTS: VS effects on the sinus node and AF inducibility were eliminated a few hours after injection of BT; these changes were not observed after injection of NS. CONCLUSION: Short-term autonomic denervation of the atria was achieved by blocking the major epicardial GP with BT.
Adipose Tissue ; Animals ; Atrial Fibrillation ; Autonomic Denervation ; Autonomic Nervous System ; Autonomic Pathways ; Botulinum Toxins ; Dogs ; Ganglion Cysts ; Sinoatrial Node ; Thoracotomy ; Veins

BACKGROUND AND OBJECTIVES: It is difficult to estimate the depth of the focal source by activation mapping. The present study was performed to demonstrate the usefulness of a simple maneuver in estimating the depth of the focal activation source (S). METHODS: A total of 44 sites (15 shallow, depth<3.5 mm; 29 deep, depth>5.5 mm) were analyzed in 3 canine left ventricles under general anesthesia. A custom-made bipolar needle electrode was used to simulate a focal activation source. A mapping catheter with an electrode tip size of 2 mm, band electrode size of 1 mm, and inter-electrode spacing of 2-10-2 mm was placed at the mapping area. The position of the center of the distal 2 electrodes was kept at the insertion site of the needle electrode. The time interval between distal and proximal electrodes of the mapping catheter (T(tachy)) was measured during needle electrode pacing. The time interval between distal and proximal electrodes (T(pace)) was measured during pacing with distal electrodes of a mapping catheter. Depth index (δ) was defined as T(tachy)/T(pace). Using in vivo data, simulation was performed to evaluate the depth and δ. RESULTS: Ttachy was 24±7.7 ms and 15±5.6 ms for shallow source and deep source simulation, respectively (p<0.001). δ values were 0.86±0.21 and 0.55±0.21 for shallow source and deep source simulation, respectively (p<0.001). According to simulation data, if δ<0.52, the depth of the focal source will be >5.5 mm. CONCLUSIONS T(tachy) was shorter and δ was smaller for a deep S than for a shallow S.

BACKGROUND AND OBJECTIVES: It is difficult to estimate the depth of the focal source by activation mapping. The present study was performed to demonstrate the usefulness of a simple maneuver in estimating the depth of the focal activation source (S).METHODS: A total of 44 sites (15 shallow, depth<3.5 mm; 29 deep, depth>5.5 mm) were analyzed in 3 canine left ventricles under general anesthesia. A custom-made bipolar needle electrode was used to simulate a focal activation source. A mapping catheter with an electrode tip size of 2 mm, band electrode size of 1 mm, and inter-electrode spacing of 2-10-2 mm was placed at the mapping area. The position of the center of the distal 2 electrodes was kept at the insertion site of the needle electrode. The time interval between distal and proximal electrodes of the mapping catheter (T(tachy)) was measured during needle electrode pacing. The time interval between distal and proximal electrodes (T(pace)) was measured during pacing with distal electrodes of a mapping catheter. Depth index (δ) was defined as T(tachy)/T(pace). Using in vivo data, simulation was performed to evaluate the depth and δ.RESULTS: Ttachy was 24±7.7 ms and 15±5.6 ms for shallow source and deep source simulation, respectively (p<0.001). δ values were 0.86±0.21 and 0.55±0.21 for shallow source and deep source simulation, respectively (p<0.001). According to simulation data, if δ<0.52, the depth of the focal source will be >5.5 mm.CONCLUSIONS: T(tachy) was shorter and δ was smaller for a deep S than for a shallow S.
Anesthesia, General ; Catheters ; Electrodes ; Heart Ventricles ; Myocardium ; Needles ; Tachycardia, Ventricular

BACKGROUND AND OBJECTIVES: The cardiac autonomic nervous system is an emerging target for therapeutic control of atrial fibrillation (AF). We evaluated the effects of low-intensity autonomic nerve stimulation (LI-ANS) on atrial electrophysiology, AF vulnerability, and neural remodeling. SUBJECTS AND METHODS: Fourteen dogs were subjected to 3 hours rapid atrial pacing (RAP, 5 Hz) and concomitant high frequency LI-ANS (20 Hz, at voltages 40% below the threshold) as follows: no autonomic stimulation (control, n=3); or right cervical vagus nerve (RVN, n=6), anterior right ganglionated plexi (ARGP, n=3), and superior left ganglionated plexi (SLGP, n=2) stimulation. Programmed and burst atrial pacing were performed at baseline and at the end of each hour to determine atrial effective refractory period (ERP), window of vulnerability (WOV), and inducibility of sustained AF. RESULTS: Atrial ERP was significantly shortened by 3 hours RAP (in control group, DeltaERP=-47.9+/-8.9%, p=0.032), and RAP-induced ERP shortening was attenuated by LI-ANS (in LI-ANS group, DeltaERP=-15.4+/-5.9%, p=0.019; vs. control, p=0.035). Neither WOV for AF nor AF inducibility changed significantly during 3 hours RAP with simultaneous LI-ANS. There was no significant difference between the control and LI-ANS group in nerve density and sprouting evaluated by anti-tyrosine hydroxylase and anti-growth associated protein-43 staining. Among the various sites for LI-ANS, the ARGP-stimulation group showed marginally lower DeltaWOV (p=0.077) and lower nerve sprouting (p=0.065) compared to the RVN-stimulation group. CONCLUSION: Low-intensity autonomic nerve stimulation significantly attenuated the shortening of atrial ERP caused by RAP. ARGP may be a better target for LI-ANS than RVN for the purpose of suppressing atrial remodeling in AF.
Animals ; Atrial Fibrillation ; Atrial Remodeling ; Autonomic Nervous System ; Autonomic Pathways* ; Dogs ; Electrophysiology* ; Ganglion Cysts ; Vagus Nerve

BACKGROUND AND OBJECTIVES: Left bundle branch block (LBBB) with left axis deviation (LAD) has a worse prognosis than LBBB with a normal axis, and myocardial dysfunction has been suggested as a cause of left axis deviation. This study investigated the prognostic significance of the QRS axis in patients with LBBB and analyzed its relationship with the amount of myocardial scarring. SUBJECTS AND METHODS: A total of 829 patients were diagnosed with LBBB at Seoul National University Hospital from October 2004 to June 2014. Of these, 314 who were asymptomatic and had no previous history of cardiac disease were included in the present study. Myocardial scarring was calculated using the Selvester QRS scoring system, and LAD was defined as a QRS axis between -180° and -30°. RESULTS: Of the total patients, 91 (29%) had LAD, and patients were followed for a median of 30 months. During follow-up, two patients were hospitalized for de novo heart failure, four had pacemaker implants, and 10 died. There was a significant inverse correlation between myocardial scar score and the QRS axis (r=-0.356, p<0.001). Patients with concomitant LAD had a higher rate of major cardiac adverse events compared with patients with a normal axis (5.5% vs. 1.3%, log-rank p=0.010); the prognostic value was attenuated in multivariable analysis (hazard ratio 4.117; 95% confidence interval 0.955-17.743; p=0.058). CONCLUSION: Concomitant LAD is an indicator of poor prognosis for patients with LBBB and may be associated with greater myocardial scarring.
Bundle-Branch Block* ; Cicatrix* ; Electrocardiography ; Electrophysiology ; Follow-Up Studies ; Heart Diseases ; Heart Failure ; Humans ; Prognosis ; Seoul