Hiroo Noguchi

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.

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.

A left atrial appendage thrombus that developed during prophylactic low-dose dabigatran treatment resolved after switching to apixaban

We describe a case of atrial fibrillation in which an intracardiac thrombus that could not be prevented with “low‐dose” dabigatran treatment was resolved by switching to apixaban treatment. Thrombolysis using direct oral anticoagulants (DOACs) could be a therapeutic option for patients with intracardiac thrombi, although the efficacies of different DOACs seem to differ and need further examination.

Black hole restenosis after drug-eluting stent implantation for in-stent restenosis: potential mechanism and optimal strategy

In-stent restenosis (ISR) has long remained as the major limitation of coronary stenting. The use of drug-eluting stent (DES) reduces the risk of repeat revascularization without an increase of death and myocardial infarction, compared to the standard bare metal stents. DES has also demonstrated markedly to reduce ISR for complex lesions. However, ISR after DES implantation still occurs and optimal treatment for ISR after DES has not been established. Herein, we report 3 cases with black hole restenosis confirmed by intravascular ultrasound at the site of overlapped DES and discuss potential mechanism and optimal strategy for this phenomenon.

Prolonged inflation technique using a scoring balloon for severe calcified lesion: Creep phenomenon

Percutaneous coronary intervention for the treatment of a severe calcified lesion is still one of the most technically challenging areas of interventional cardiology. Calcified lesions are a cause of stent underexpansion, which significantly increases the subsequent risks of in-stent restenosis and thrombosis, even when drug-eluting stents are used. In this report, we describe the usefulness of prolonged inflations using a scoring balloon catheter (Scoreflex) for severe calcified lesions. Prolonged inflation using a scoring balloon enables an adequate dilation for treatment of a severe calcified plaque that was unresponsive to conventional technique with or without rotational atherectomy.