Myocardial Ischemia as a Genuine Cause Responsible for the Organization and “Fertilization” of Conflictogenic Atrial Fibrillation:New Conceptual Insights into Arrhythmogenicity

Citation: Petras Stirbys MD, PhD

Atrial fibrillation continues to be a challenging arrhythmia. There are some conventional, time-tested explanations of atrial fibrillation genesis, however some uncertainty of its complete understanding still exists. We focused on atrial ischemia which, hypothetically, could be responsible for manifestation of the arrhythmia, irrespective of the underlying heart disease. Evidences abounds that atrial fibrillation has an extremely strong association with nutritional/oxidative status of myocardium. This arrhythmia seemingly may stem from the electrophysiological differences taking place in the boundary areas. To validate such assumptions we have surveyed widely accepted theories based on clinical and experimental evidence. There was an attempt to integrate some well-known theoretical explanations (focal, multifocal, ectopic, reentrant activity, atrial remodeling, etc.) into a new conceptually systematized arrhythmogenesis. Confronting ischemic and non-ischemic atrial zones electrophysiologically on their borderlines presumably creates a substrate vulnerable to the development of atrial fibrillation. The behavior of these interrelated areas is likely ischemia-dependent; the separating borderline(s) may be treated as conflictogenic, releasing triggers/drivers to commence and to perpetuate the arrhythmia. Ischemically damaged and non-damaged myocardial areas likely participate in the relay-race carousel of arrhythmogenicity due to their mutual interactions, accompanied by the “fireworks” at the separating borderlines. It could be concluded that myocardial ischemia as a nonspecific proarrhythmic factor presumably plays a key role in the genesis and sustenance of atrial fibrillation. Theoretically the most important step in eradication of arrhythmogenic substrate might be an overall abolition of ischemia regardless of the characteristics of underlying heart disease. Innovative intellectual and explorative research is needed to render innocuous the ischemia that might help us win the century’s cardioarrhythmological battle.

Left Atrial Fibrosis: Role in Atrial Fibrillation Pathophysiology and Treatment Outcomes

Citation : David Spragg, MD

The mechanisms of atrial fibrillation are complex, and have been the subject of intensive study for over fifty years. There is likely a complex interplay between triggers and substrate that mediates the initiation and maintenance of AF. Increasingly, atrial fibrosis has been recognized as a key component of that substrate, playing a critical role in conduction abnormalities in the left atrium that appear necessary to maintaining AF. In the last several years, our abilities to quantify left atrial fibrosis – both through catheter- and MRI-based techniques – has shed important light on the underlying mechanisms of AF, and on therapeutic strategies to treat AF. Whether our increased appreciation of the role of atrial fibrosis in AF translates into improved efficacy of catheter ablation or anti-arrhythmic therapy, though, remains to be seen. The aim of this review is to summarize clinical investigations of atrial fibrosis as a factor in the development and treatment of atrial fibrillation.

Collateral Damage from Catheter Ablation of Atrial Fibrillation: Lessons Learnt in the Past Decade

Citation : Wanwarang Wongcharoen, MD, Li-Wei Lo, MD, and Shih-Ann Chen, MD

Catheter ablation for atrial fibrillation (AF) has been increasingly performed over the past decade. Regardless of technological advances and technique improvement, catheter ablation for AF remains a highly complex procedure and the risk of procedural complications is not negligible. This article discusses the management and the approach to avoid the serious complications of catheter AF ablation including pulmonary vein stenosis, atrioesophageal fistula, cardiac tamponade, stroke and collateral nervous damage. The management of periprocedural anticoagulation and the complications associated with epicardial AF ablation are also described.

Role of Stress in Cardiac Arrhythmias

Citation : Vladimir Shusterman, MD, PhD and Rachel Lampert, MD

Stress is a major trigger of cardiac arrhythmias; it exerts profound effects on electrophysiology of the cardiomyocytes and the cardiac rhythm. Psychological and physiological stressors impact the cardiovascular system through the autonomic nervous system (ANS). While stressors vary, properties of the stress response at the level of cardiovascular system (collectively referred to as the autonomic cardiovascular responses) are similar and can be studied independently from the properties of specific stressors. Here, we will review the clinical and experimental evidence linking common stressors and atrial arrhythmias. Specifically, we will describe the impact of psychological and circadian stressors on ANS activity and arrhythmogenesis. We will also review studies examining relationships between autonomic cardiovascular responses and cardiac arrhythmias in ambulatory and laboratory settings.

Cerebral Embolization During AF Ablation – Pathophysiology, Prevention and Management

Citation : Nasir Shariff, MD, Nagesh Antha, MD, Manish Roy, MD, Hari Joshi, MD, Vadim Levin, MD

Catheter based ablation therapy has evolved as an invaluable tool in the management of symptomatic patients with atrial fibrillation (AF). The procedure of AF ablation requires instrumentation in the systemic circulation predisposing to various concerns that can result in systemic embolization. We will describe the reported incidence of these events and refer to the various pathophysiologic explanations for their occurrence. Details on the risk factors and the relevant studies will also be reviewed. Preventive and treatment strategies in patients undergoing the ablation procedure will be discussed.

Cryo-Balloon Ablation of the Right Superior Pulmonary Vein Involving the Anterior Right Ganglionated Plexus for Speech and Breathing Induced Atrial Tachycardia

Citation : Aharon Medina, MD, Mickey Ilan, MD, Dan Tzivoni, MD

Targeting ganglionated plexi (GP) during catheter ablation of atrial fibrillation (AF) is associated with improved outcome. We present a patient with speech and breathing induced atrial tachycardia (AT) originating in the superior vena cava (SVC) and the right superior pulmonary vein (RSPV), near the anatomical location of the anterior right GP (ARGP). The trigger for the arrhythmia appeared to be vagal discharge from the GP, possibly induced by local stretch. Ablation with a 28 mm cryo-balloon advanced to the RSPV orifice through a patent foramen ovale (PFO) abolished the arrhythmia, probably involving the underlying parasympathetic influx to the SVC and RSPV myocardial sleeves.

Three-Dimensional Transoesophageal Echocar - diography in Electrophysiology Laboratory

Citation : Mustafa Yildiz, Cuneyt Toprak

Percutaneous electrophysiological interventions such as atrial fibrillation and ventricular tachycardia ablation are usually monitored by fluoroscopy and electroanatomical mapping systems. Electroanatomical mapping systems lacks soft tissue contrast and adequate visualization of the target area such as right ventricular out-flow tract and left atrium. Recently, real-time 3D transoesophageal echocardiography (RT-3D TEE) has emerged as an important method for visualizing cardiac structures such as left atrium, left atrial appendix, interatrial septum, pulmonary veins, Marshall ligament and mitral valve annulus during invasive procedures. This review aims to describe the RT-3D TEE for the guidance of percutaneous interventional electrophysiological study especially at atrial fibrillation in the cardiac electrophysiology laboratory.