Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, but pathophysiological processes underlying AF remain incompletely understood, despite extensive basic and clinical researches. They involve alterations of ion channels, gap junctions and intracellular Ca2+ handling by the sarcoplasmic reticulum at the cellular level, and various changes at the organ level affecting atrial tissue architecture. In addition, there is evidence supporting that inflammation, oxidative stress, metabolic disorders and changes in autonomic nervous function contribute to abnormal electrical activities leading to AF. It is well stablished that the paroxysmal type of AF is related to focal sources mainly in the extra-atrial tissue (e.g., pulmonary vein myocardium), as confirmed by the clinical efficacy of electrical isolation of these foci from the atrial tissue. In contrast, the mechanisms maintaining long-lasting AF are still controversial and may involve both ectopic focal impulse generation and various forms of reentry. Two conflicting hypotheses have been proposed as a reentrant mechanism: stable rotors at fixed locations produce sustained electrical activity of AF (mother rotor hypothesis), and breakup of random excitation waves generating multiple wavelets maintains AF (multiple wavelet hypothesis). The progression of paroxysmal AF to persistent AF is mediated by electrical and structural remodeling, the former highlights an abbreviation of atrial refractory period and cell-to-cell electrical uncoupling, and the latter includes proliferation of myofibroblasts and interstitial fibrosis. In this symposium, four distinguished speakers will give talks on these issues and discuss the initiation and perpetuation mechanisms of AF.

Recently, the therapeutic and diagnostic tools and devices in atrial fibrillation make remarkable progress as follows.

• Contact-force sensing technology in RF catheter ablation has the potentials to increase the durability of pulmonary vein isolation (PVI) and to improve the learning curve of young physicians. And recent new parameters such as Ablation Index (CARTO) and LSI (Navx) were correlated to the ablation lesion depth and were promising to improve the ablation procedure.
• Balloon ablation technology (Cryoballoon, Hot balloon and Laser balloon) was remarkably advanced. Especially, Cryoballoon ablation was able to create the durable PVI and to reduce the procedure time. Several reports indicated that the efficacy of each balloon ablation for paroxysmal atrial fibrillation was as same as RF catheter ablation. However, balloon ablation has the potential risk of pulmonary vein stenosis and phrenic nerve palsy. So, the further examinations to avoid these complications are required.
• 3D mapping system was very useful and essential to catheter ablation for atrial fibrillation. Recently, auto mapping system was developed on each 3D mapping system (Confidense(CARTO),Auto-mapping(Navx), and Rhythmia). Each system was able to represent the reentrant circuit and the focal source of atrial tachycardia and fibrillation. Especially, the ORION catheter of Rhythmia system has the 64 small electrodes and can clearly record the fractionated potential on slow conduction area without far field potential.

This session will present recent advances in these novel therapeutic and diagnostic tools and devices in atrial fibrillation. These advances aim to improve the procedure time and optimize procedural outcomes.

In contrast to the well-established treatment for paroxysmal atrial fibrillation, catheter ablation for persistent or long-standing persistent AF (PerAF/LSPAF) is still a big challenge with various controversies remained.
Firstly, indication of ablation is still debatable, because most of PerAF/LSPAF patients are asymptomatic. Although regardless of the absence of serious symptoms in these patients, their poorer QOL than paroxysmal AF patients has been shown, which can be improved by restoring sinus rhythm by ablation treatment through the increase of LV systolic function and the exercise tolerance capability.
Optimal ablation strategies for PerAF/LSPAF also remain to be debatable. Less advanced persistent cases have been shown to be cured by a simple pulmonary vein isolation technique, however additional techniques to reduce the substrates perpetuating AF are necessary to conquer PerAF/LSPAF. Although various methods have been developed so far (linear ablation, CFAE, GP, Rotor/Driver, LVZ, etc), there has been no established method demonstrating obvious advantages to others. An order-made therapy with the selection of appropriate treatment in each case will be necessary to improve the outcome of ablation for PerAF/LSPAF patients.
In this symposium, we want to discuss the indications, meanings, and the strategy issues of catheter ablation to conquer PerAF/LSPAF.

最近まで上室性頻拍の電気生理的診断法・治療法は、多くの成書に示されているように確立した感があった。しかし、房室結節リエントリー性頻拍の新たな一亜型の報告を契機に、房室結節及びその周囲から発生する頻拍の概念の再考が求められている。とりわけ、従来から認知されているいわゆるATP感受性心房頻拍との関連・異同、電気生理学的な鑑別診断がまず直面する問題点である。なぜなら、頻拍の機序を的確に診断することが、リエントリー回路の局在の推定、さらにアブレーション・ストラテジーの選択につながるものと考えられるからである。実際に一部に難治例が存在することは未解明の課題の存在を暗示しているとも思われる。さらに重要なのは近年房室結節及びその周囲に新たな基質の存在が解剖学的・生化学的に明らかにされつつあることであり、頻拍概念の基盤となる可能性がある。新知見と従来から蓄積された知見との整合性をどのようにとりながら理解し展開するか、その作業は容易ではないものの、学術的にも発展性のある魅力的な領域である。本シンポジウムでは、最新の知見に基づいてこれらの問題点について議論を行い、日本不整脈界が誇る上室性頻拍の診療・研究の最前線に迫りたい。

この30年で心室性不整脈に対するカテーテルアブレーション治療は格段の進歩を遂げた。特に3-Dマッピング法の導入によって複雑な頻拍機序の解析や、より詳細なアブレーション標的の同定が可能となった。器質的心疾患を有する患者においては、心室頻拍（VT）の主な基質は心筋瘢痕の複雑な不整脈原性構造である。3-Dマッピングシステムを用いた基質マッピングの出現により器質的心疾患におけるVTアブレーションの成功率は劇的に改善されたが、まだ限界も多い。また、たとえ標的部位が詳細に同定されたとしても、頻拍起源によってその治療効果に未だ大きな差が存在していることも事実である。 このシンポジウムでは、新たなマッピング方法とアブレーション技術、例えば多点高密度マッピング、周波数解析マッピング、心外膜アプローチ、バイポーラ・アブレーション、ニードル・アブレーション、化学アブレーションなどの最新の技術を紹介し討論したい。これらの新たな技術は、不整脈基質を正確に理解した上で、アブレーション成績を向上させる新たな戦略になるものと期待される。

The history of implantable pacemaker is over a half century, and approximately 60,000 patients receive pacemakers annually in Japan. However, conventional pacemakers are known to be associated with several adverse events. Majority of the adverse events are related with the lead or subcutaneous pocket. The leadless pacemaker was invented to overcome these known complications. The approval of the leadless pacemaker in Japan was in September, 2017. Japanese patients are small and often have known risk factors for cardiac perforation. As more patients receive the leadless pacemaker, possibly DDD in future, we would like to discuss the current status, future direction and possible procedure tips for the safe implant.

Cardiovascular implantable electronic device (CIED)-associated infection is a serious and sometimes fatal problem after device implantation. It has been reported to occur around 1-7% of cases, but it is gradually increasing recently because of expanded function and device indication. For prevention, appropriate management before/during the implantation (patient selection, preventative maneuver and choice of device) is important. But once infection occurred, the mainstream of the management is a total removal of these devices, however it sometimes causes fatal complication including death. From the early 1990s, lead extraction system for CIED has progressed. Excimer laser system has approved in 2010 and now a standard therapy for CIED-associated infection in yearly 500 cases in Japan. J-LEX (Japanese registry of Lead Extraction) will provide a current situation in this filed.
In this session, we will make a discussion with experts about the prevention and the appropriate management for CIED-associated infection, especially focus on the patient selection and the recent advancement of lead extraction system.

In Japan, implantable cardioverter-defibrillators (ICDs) were approved by the Japanese Ministry of Health, Labor and Welfare in 1996. Then, the first guidelines for ICDs were published by the Japanese Circulation Society in 2001. CRT-P and CRT with an ICD (CRT-D) were also approved in 2004 and 2006, respectively. The ICDs were a first grade therapy to prevent sudden cardiac death worldwide, even in Japan. The indication for ICDs seemed to have been confirmed. The indication for ICDs for secondary prevention, in particular, for sudden cardiac death, had already been established nearly 20 years after the approval of ICDs in Japan. However, Japan is now aging and is about to enter an unprepared for super-aging society. Therefore, new problems are arising as to how to consider ICD indications not only for primary prevention, but also for secondary prevention in patients with comorbidities and that are super-aged and frail. In this symposium, we would like to reconsider how to consider these problems and the indications for ICDs.

Although cardiac resynchronization therapy (CRT) has been proven to improve the prognosis of patients with a reduced cardiac function and wide QRS complex, a substantial number of candidates do not have a favorable clinical response. The exact rate of non-responders is still unclear because various definitions of non-responders have been used among the studies. The recent trials are prone to using a clinical composite score, which includes the clinical response (NYHA class and exercise duration), reverse remodeling (increase in the LVEF and a reduction in the systolic or diastolic dimension of the LV), and outcome measurements (hospitalization, morbidity, and mortality).
Since the causes of non-responders are multifactorial (patient selection, inadequate AV and/or V-V timing, a sub-optimal left ventricular lead position, and a conduction delay within the LV), various efforts to resolve these problems have been challenged. Owing to the advanced CRT features for heart failure, the rate of non-responders has seemed to improve. In this symposium, the most advanced technologies to obtain cardiac synchronization and the near future of CRT will be discussed.

Most cardiovascular implantable electronic devices (CIEDs) currently use leads that connect the generator to cardiac tissue. Lead management is an important issue, given the lead failures, generator changes, and clinical conditions that can directly affect CIEDs. The previous expert consensus ‘Transvenous Lead Extraction: Heart Rhythm Society Expert Consensus on Facilities, Training, Indications, and Patient Management’ was published in 2009. In that consensus document the complete removal of the entire CIED system was recommended in cases with confirmed or suspected pocket infections of the implanted devices. Regarding non-infectious indications, chronic pain induced by the device system and undergoing specific imaging such as MRI were class IIa indications for a lead extraction. Further, this statement also provided several conditions involving thrombosis or venous stenosis, and functional or non-functional leads, as class I or IIa indications. Moreover, that document delivered detailed recommendations for facilities and training on lead extractions that remain appropriate.
In September 2017, the new statement ‘2017 HRS Expert Consensus Statement on Cardiovascular Implantable Electronic Device Lead Management and Extraction’ was announced. The main focus of this new statement is to provide practical clinical guidance in the broad field of lead management, including lead extractions. Therefore, we can learn a lot about the latest management of CIED systems. However, regarding non-infectious indications, the optimal decision-making process regarding lead extractions for noninfectious indications is less clarified, because it is unclear whether the risk of an extraction outweighs the benefit of having the lead removed in many situations, for example with ‘recalled leads’, ‘abandoned or non-functional leads’, ‘taking MRI imaging in patients with non-MRI conditioned devices’, and even ‘functional leads’. In this session, we would like to discuss the non-infectious indications of lead extractions

原因不明の失神患者に対する長期間の心電図記録装置には、体外式ループ式心電計あるいは植込み型ループ式心電計が広く利用されている。これらの長時間心電計は、失神発作時の心電図異常が直接捕らえられることから原因診断に非常に有用であることは多くの科学的エビデンスで明らかである。失神時に、10秒以上もの長い心停止が捕まることも稀ではない。しかし心停止の原因には、器質的異常を伴う刺激伝導系の異常、即ち洞不全症候群や房室ブロック（一次性あるいは原発性）がある一方で、刺激伝導系に何ら異常を認めない機能的な心停止（二次性の洞不全や房室ブロック）が失神の原因となっていることがある。後者は、てんかん発作や反射性失神でみられ、自律神経系の一過性機能異常で発生している。一次性の刺激伝導系異常が原因の場合には、いわゆる心原性失神とみなされ、徐脈の治療としてペースメーカ治療は有効である。しかし、二次性の場合は非心原性（てんかん、心抑制型の血管迷走神経性失神）が原因であることが多く、ペースメーカ治療の有効性は確立しておらず、植込み後に失神再発を認めることが多い。
本シンポジウムでは、失神患者の原因が長い心停止であることが判明した場合、どのような観点から一次性と二次性の鑑別を行なうべきかに焦点を当て、非心原性失神で心停止を来す症例には、どの様な症例にペースメーカ治療が期待され、どの様な症例にペースメーカ治療を行なうべきではない、等々について広く議論したいと考えている。心停止が捕らえられた患者に安易にペースメーカ治療を行ない、その後も失神再発を認める患者とトラブルになったケースも散見される。臨床上、極めて重要な問題であり、多くの参加者を期待している。

The autonomic nervous system is involved in regulation of electrophysiological properties in cardiac tissues. Abnormal autonomic states have been shown as a strong prognostic marker of increased mortality and propensity to lethal arrhythmias. Activation of the sympathetic nervous system enhances automaticity or triggered activity, accelerates conduction and shortens refractory period, thereby leading to induction of atrial as well as ventricular tachyarrhythmias. Activation of the parasympathetic nervous system exerts protective effects against ventricular tachyarrhythmias. However, activation of the parasympathetic nervous system is associated with induction of atrial fibrillation in apparently healthy subjects and ventricular fibrillation in patients with Brugada syndrome. Modulation of the autonomic nervous activity with invasive techniques is now becoming promising treatment strategies for some specific tachyarrhythmias. For instance, ablation of the atrial epicardial ganglionated plexus is effective in suppressing paroxysms of atrial fibrillation. Additionally, cervical vagal nerve stimulation, left stellate ganglionectomy and renal sympathetic denervation could be now promising, adjunctive treatment techniques for refractory arrhythmias. Indeed, left stellate ganglionectomy is effective in suppressing ventricular tachyarrhythmias in patients with catecholaminergic polymorphic ventricular tachycardia as well as long QT syndrome. In this symposium, arrhythmogenic mechanisms of neurocardiac interactions and recent progress in modulation of the autonomic nervous activity for treatment of refractory arrhythmias will be discussed.

本邦は未曽有の高齢化を迎え、社会の様々な分野でこれまでの仕組みや考え方では対応できない時代を迎えている。このような「高齢化」は、成熟した分野ほど大きな影響を与えるが、不整脈はその最たるものの一つと言えるかもしれない。これまでの無作為化比較試験（RCT）では除外されてきた患者が徐々に主役となる分野で、RCTの結果をどのようにとらえなおすべきだろうか。また、このようなRCTによって策定されたガイドラインは実用に耐えうるのだろうか。そもそもこのような超高齢化社会でのガイドラインはどうあるべきなのだろうか。本シンポジウムでは、このような難しい課題に対して、自由闊達な議論を行いたい。答えはまだ全くない。これから皆で築くのである。これまでのガイドラインの策定、内容などを、これからも延長しよう、新しく少し修正すればよいなどと考えるのは愚の骨頂である。その討論対象は、抗不整脈薬、心拍数調節薬、抗凝固薬、カテーテルアブレーション、植え込み型デバイスなど多岐にわたり、それぞれを一から考え直すことが必要であろう。

不整脈に限らず、すべての疾患の病態発現に遺伝因子と環境因子の両者が関与する。それぞれが関与する割合は疾患によりさまざまである。不整脈では、遺伝因子の関与が強い先天性QT延長症候群、遺伝因子の関与が強いがそれだけでは完全に説明できないBrugada症候群、両者の貢献がほぼ50:50である心房細動などがある。これは、それぞれの不整脈の臨床像の違いに反映される。環境因子の関与の強い心房細動は、高血圧・糖尿病などの生活習慣病がリスク因子となる。一方、先天性QT延長症候群やBrugada症候群では生活習慣病の関与は少ない。ただし、環境因子が全く病態に関与しないわけではなく、電解質異常や自律神経などが不整薬発作の誘因となる。本シンポジウムでは、遺伝性の強い不整脈から比較的弱い不整脈まで、また臨床に近い研究から純粋な基礎研究まで、幅広く最近興味深い展開をもたらした演題を募る。これによって、不整脈の遺伝学の全体像を理解していただき、臨床家の方にはこの知見を日常臨床にどのように生かしたらよいのか、一方これから当該領域に参入を考えている研究者には、何が残された疑問点でどのようなアプローチを取ったら良いのか、のヒントをつかんでいただくシンポジウムにしたい。

近年、臨床心臓電気生理学的技法の進歩により、不整脈の発生起源や興奮伝導様式が正確に把握できるようになり、カテーテルアブレーションによる不整脈治療は目覚ましく発展を遂げた。しかしながら、アブレーションでは根治できない難治性の致死性不整脈も多く存在する。こうした不整脈では、その病因となる心筋機能分子の異常や組織形態の異常などの発生基質と発生機序を把握しておくことが治療上不可欠になる。実験的研究では、遺伝子改変技術や蛍光プローブを用いた光学技術の進歩により、細胞から組織・臓器に至る幅広いレベルでのカルシウムや膜電位の蛍光強度変化から「不整脈を可視化」できるようになり、その原因遺伝子・分子や組織形態の異常がどのようにして不整脈を惹起するかが理解できるようになってきた。またヒトの疾患特異的iPS細胞から分化誘導した心筋細胞を用いて「不整脈を再現」することも可能になり、個別化医療に繋がる結果も得られつつある。本シンポジウムではこのような多様なモダリティーを用いた不整脈の基礎的研究の成果からその発生機序を論じるとともに、新たな治療戦略についても展望したい。

小児・先天性心疾患には、原疾患による不整脈と心内修復術に伴う不整脈が発生する。原疾患に伴う洞機能不全、房室伝導障害、また術後不整脈としての徐脈性不整脈に対する治療はペースメーカーが主流であるが、心臓アクセスルート制限、心内シャント存在などで心内リードを利用する通常のペースメーカー植込手術ができない場合がある。頻脈は特殊な副伝導路やtwin AV nodeによる房室回帰性頻拍、術後頻拍や心房負荷が強い病態でみられる多発性心房頻拍、心房細動などがあり、治療はカテーテルアブレーションの役割が大きいが、全般的に難治性である。植込型除細動器（経静脈、皮下）とのハイブリッド治療、原疾患に対する外科的介入も有力であるが、十分なエビデンスは構築されていない。この多彩でチャレンジングな分野における最先端治療を広く検討し、今後の展開を俯瞰してみたい。

As more complex rhythm disturbance has become the target of EP study and catheter ablation, the technology of electro-anatomical mapping (EAM) system has been rapidly developed. At present, we have several different EAM systems with some specific features, such as capability to make a prompt mapping for non-sustained unstable arrhythmias, ability to display all catheters’ positions and rapid depiction of cardiac geometry. For the procedural success, it is essential to use each EAM system with a deep understanding of the characteristics of the system as well as to make a careful interpretation for the acquired data. In this session, with regard to the clinically available EAM systems, how to master the new technology to make a profit for the patients will be discussed. Further the new system currently under the development will be introduced, particularly focusing on the principal benefits and future perspective in this field.

Cardiomyopathy is cardiac disorder that causes heart failure and rhythm disorders such as supraventricular and ventricular arrhythmias. Sudden cardiac death (SCD) is primarily caused by ventricular tachycardia (VT)/fibrillation (VF). Therefore, the prevention of VT/VF is a key issue in the treatment of patients at risk for SCD. Atrial fibrillation (AF) frequently occurs in patients with cardiomyopathy. It is recognized that AF leads to clinical deterioration and worsened hemodynamics. However, the mechanisms of arrhythmias associated with various cardiomyopathies are complex and heterogeneous. The etiology of arrhythmias associated with dilated cardiomyopathies is known to be the result of a variety of electrical abnormalities, but the primary cause is not well understood. Arrhythmogenic right ventricular cardiomyopathy is slowly progresses to more diffuse ventricular dysfunction. In the early phase of this cardiomyopathy, structural change is absent or minor, but patients may be at risk of SCD. For hypertrophic cardiomyopathy, the predictive value of each of established clinical risk factors is poor and risk stratification for SCD remains a challenge. Drug therapy including beta-blockers and amiodarone, implantable cardioverter-defibrillator and radiofrequency ablation are important tools in the management of arrhythmia and SCD in patients with cardiomyopathy, but further investigation is necessary. Thus, each cardiomyopathy also results in different risk assessment and treatment approaches for arrhythmia. There are still many unresolved problems about cardiomyopathy and arrhythmias. In this symposium, we would like to discuss topics related to these issues, ranging from the basic sciences to clinical managements.