Tomoo Yasuda

Role of rapid focal activation in the maintenance of atrial fibrillation originating from the pulmonary veins.

Most episodes of focal atrial fibrillation (AF) can be initiated by premature beats originating from the pulmonary veins (PV). However, the role of rapid focal activation in the maintenance of AF is unclear. Thirty‐two patients with focal AF who underwent focal ablation of triggering ectopic beats were studied. Bipolar electrograms from all four PVs were recorded simultaneously. The cycle length (CL) of RFA at sites that triggered AF was measured at AF onset, after 5 minutes of sustained AF, and just before the spontaneous termination of 32 episodes of nonsustained AF. Fifteen episodes of sustained AF (> 10 minutes) and 17 episodes of nonsustained AF (5–120 seconds, mean 56 ± 59 seconds) were analyzed. In sustained AF, the mean CL of RFA in the PV from which it originated was not significantly different than in the other PVs, and RFA was continuously observed. In nonsustained AF, the mean CL of RFA in a PV from which it originated was significantly shorter than in other PVs and, when RFA disappeared, AF terminated. RFA in 1 PV induced RFA in another PV. In conclusion, widespread conduction of RFA from a PV at its source to the other sites may be necessary for the sustenance of AF. A PV interaction, a RFA triggering another, may be involved in the maintenance of AF. RFA arising from PVs is important not only as a trigger of onset, but also in the maintenance of AF.

Treatment of mixed atrial fibrillation and typical atrial flutter by hybrid catheter ablation.

Successful isthmus ablation of typical atrial flutter mixed with atrial fibrillation (AF) may favorably modify the subsequent course of paroxysmal AF. However, the source of ectopic beats triggering AF may be located in the pulmonary veins (PV). This study compared the results of combined isthmus and focal ablation with ablation limited to the isthmus in patients with mixed AF and typical atrial flutter. Thirty patients with typical atrial flutter and AF were treated. Ablation limited to the isthmus was performed in 14 patients (group A), and 16 patients underwent focal ablation of triggering ectopic beats combined with isthmus ablation (group B). Successful linear ablation of the isthmus was accomplished in all patients. In group A, AF was eliminated in 4 patients (29%) after isthmus ablation. In group B, the origin of 26 foci triggering AF (1 focus in 38% of patients, 2 foci in 31 %, 3–4 foci in 31 %) was found in the PV in 93% (left superior: 46% left inferior: 21%, right superior: 25%) and the right atrium in 7% of instances. AF was eliminated in 11 patients (69%) after ablation of these foci. The success rate in group B was significantly higher than in group A (P < 0.05). In conclusion, in cases of mixed AF and typical atrial flutter, episodes of AF originated from PV foci in >90% of instances. These findings suggest that isthmus ablation combined with PV focal ablation may be effective in mixed AF and typical atrial flutter.

Effects of the Na+ channel blocker pilsicainide on the electrophysiologic properties of pulmonary veins in patients with atrial fibrillation

Introduction: Na+ channel blockers are used to treat atrial fibrillation (AF). However, the effects of Na+ channel blockers on the electrophysiologic properties of pulmonary veins (PVs) are not well characterized. The aim of the present study was to evaluate the effect of the pure Na+ channel blocker pilsicainide on the PVs.

Isolated pulmonary arterial stenosis caused by Takayasu's arteritis in an elderly male

Takayasus arteritis has often been difficult to diagnose because of a lack of typical symptoms and other specific makers. We report here a case of Takayasus arteritis in a 73-year-old man who was considered to exhibit isolated pulmonary artery involvement. Pulmonary hypertension and right heart failure and severe stenosis in the main trunk and left pulmonary artery were observed. There was nothing remarkable in his routine blood-sample tests other than increased CRP and ESR. There were neither infectious nor collagen diseases. Anti-cardiolipin antibody, Antiphospholipid Syndrome, PR3-ANCA and MPO-ANCA were negative. We diagnosed the patient as having Takayasus arteritis based on chronic inflammation and the morphologic features of pulmonary artery lesion. However, other large vessels and the aorta were not involved. Treatment was started with glucocorticoids. The symptoms gradually improved, and pulmonary artery pressure estimated by echocardiography decreased along with inflammatiory markers. There were no remarkable changes in the stenotic lesions in the pulmonary artery but the flow limit in the left pulmonary artery was improved.

Pilsicainide for Atrial Fibrillation

Pilsicainide is a class IC antiarrhythmic drug, which has a pure sodium channel blocking action with slow recovery pharmacokinetics. In experimental studies, pilsicainide has a depressant effect on intra-atrial conduction and a prolonging effect on the atrial effective refractory period (ERP). In patients with paroxysmal atrial fibrillation (AF), pilsicainide significantly prolonged the ERP of the distal pulmonary vein (PV), PV-left atrium (LA) junction and LA, and the conduction time from the distal PV to the PV-LA junction. In some patients, PV-LA conduction block has been observed just before pilsicainide-induced termination of AF; this isolation of the PV may provide a new insight into the mechanism of pharmacological conversion of AF. Hybrid therapy with pilsicainide and PV isolation (by radiofrequency catheter ablation) appears to be an effective therapeutic approach for AF. The pharmacological PV isolation by pilsicainide and its suppression of focal discharges from atrial tissue may prevent the development of AF after unsuccessful ablation.

New Technique for Simultaneous Catheter Mapping of Pulmonary Veins for Catheter Ablation in Focal Atrial Fibrillation

Introduction: Most focal atrial fibrillation (AF) can be triggered by premature beats from pulmonary veins (PVs), and ablation of these foci could cure AF. However, it is difficult to locate the trigger points of PVs using only one mapping catheter. The purpose of the present study was to investigate the efficacy of using four mapping catheters in four PVs simultaneously in the ablation of focal AF. Methods and Results: Thirty-two patients with frequent attacks of paroxysmal AF triggered by PV foci were included. After a transseptal procedure, three 2-french microcatheters and one 7-french catheter for ablation were placed into each of the PVs, and mapping of the four PVs was performed simultaneously. Fifty-eight foci were identified; 51 triggers (88%) originated from the PV and 7 (12%) from atrial tissue. The trigger points of AF were found in a single focus in 14 patients, in 2 foci in 12 patients, and in 3–4 foci in 6 patients. During a mean follow-up period of 10 ± 4 months, ablation eliminated AF without drugs in 86, 50 and 33% of the patients with 1, 2 and 3–4 targeted PVs, respectively; 20 patients (63%) were successfully ablated. Age, history of AF, the dimension of the left atrium and the number of focal origins were significant predictors of success. Conclusion: The technique of simultaneous mapping of PVs using quadruple catheters is a feasible and effective method for mapping the trigger points and ablation of focal AF originating from PVs.

Characteristics of the conduction of the left atrium in atrial fibrillation using non-contact mapping

BACKGROUND We evaluated the conduction properties of the posterior left atrium (LA) using a non-contact mapping (NCM) system as well as the significance of linear ablation at the roof of the posterior LA (LA roof) and inferior region of the posterior LA (LA bottom). METHODS AND RESULTS In 133 patients with atrial fibrillation (AF) (83 paroxysmal type, 50 persistent/long-lasting persistent type), we performed complete isolation of the posterior LA including pulmonary veins (Box isolation) using NCM. Isochronal activation maps were analyzed during sinus rhythm (SR), during pacing from the proximal coronary sinus (CS), and during pacing within the posterior LA before and after ablation. In sinus rhythm, horizontal conduction along the LA roof line, but not into the posterior LA wall, was observed in 59% of the patients. During paroxysmal CS pacing, horizontal conduction along the LA bottom line was observed in 69% of the patients. Posterior wall pacing conducted vertically over the LA roof and bottom lines in 98% and 83% of the patients, respectively. During AF, rotor wave conduction into the posterior LA through the LA roof and bottom lines was observed in 85% of the patients. Heterogeneous conduction directions in the posterior LA at the LA roof and bottom lines were observed in 60% of the patients. CONCLUSIONS Heterogeneous conduction was observed at the roof and inferior region of the posterior LA in most of these AF patients. The conduction properties of the posterior LA are affected by the direction of the wavefronts, and this may play an important role in the initiation and maintenance of AF. The complete isolation of the posterior LA may prevent AF.

Comparison of the Effects of Na+ and K+ Channel Blockers on the Electrophysiological Properties of the Pulmonary Veins in Patients with Atrial Fibrillation

Introduction: We assessed the effects of pilsicainide, a pure Na+ channel blocker, and nifekalant, a pure rapid delayed rectifier potassium current (IKr) blocker, on the electrophysiological characteristics within the pulmonary vein (PV) and at the PV‐left atrial (LA) junction.

Circadian variations in laboratory measurements of coagulation assays after administration of rivaroxaban or warfarin in patients with nonvalvular atrial fibrillation

BACKGROUND Although rivaroxaban has a relatively shorter half-life and peak and trough plasma concentrations throughout the day than warfarin, rivaroxaban has been found to be non-inferior to warfarin in preventing thromboembolic events in patients with nonvalvular atrial fibrillation (NVAF). We measured circadian variations in laboratory measurements of coagulation assays for chronic treatment with rivaroxaban or warfarin in patients with NVAF. METHODS We included 28 consecutive patients with NVAF who were treated with rivaroxaban (n=13) or warfarin (n=15). Blood samples were collected at 6 AM, 11 AM, and 3 PM on the same day and on the next morning at 6 AM. Prothrombin time (PT), international normalized ratio of the PT (PT-INR), activated partial thromboplastin time (APTT), prothrombin fragment 1+2 (F1+2), and protein C level/activity were measured in each patient. RESULTS PT and PT-INR were significantly and consistently lower, and the F1+2 and protein C level/activity were significantly and consistently higher throughout the day in rivaroxaban-treated patients than in warfarin-treated patients. Significant increases in PT and PT-INR were observed 3h after oral administration in the patients taking rivaroxaban in the morning, whereas, significant increases in the protein C level/activity were observed 3h after oral administration in the patients taking warfarin in the morning. CONCLUSIONS The protein C level/activity was significantly and consistently higher in the rivaroxaban-treated patients than in the warfarin-treated patients throughout the day, which was in contrast to the findings for other coagulation assays. These findings may partly explain the specific persistent anticoagulant effects of rivaroxaban even during the trough phase of the plasma concentration.

Frequent Premature Ventricular Complexes Originating from the Left Ventricular Summit Successfully Ablated from the Proximal Great Cardiac Vein Using an Impedance-based Electroanatomical Mapping System.

We herein report a 58-year-old woman with frequent premature ventricular complexes (PVCs) originating from the left ventricular summit. The earliest ventricular activation of spontaneous PVCs was recorded in the proximal site of the great cardiac vein, which was simultaneously mapped and conducted using an impedance-based electroanatomical mapping system. Irrigated radiofrequency with a starting power output of 20 W and maximal temperature set at 40°C was applied with 10 Ω impedance fall, resulting in total disappearance of the frequent PVCs. The patient has remained free from PVCs for 18 months without requiring antiarrhythmic drug therapy.