Understanding Atrial Fibrillation

A new guide to the mechanisms and principles behind the world’s most common abnormal heart rhythm  Affecting 30 million or more people across the globe, atrial fibrillation is one of the most prevalent – and yet misapprehended – issues facing modern cardiology. Its potential causes and optimal treatment strategies are matters of some conjecture in the medical community, where ongoing research has yielded findings that can prove challenging to those not familiar with the complex physiology at the root of the condition. Recognizing these concerns, distinguished electrophysiologist Peter Spector has designed Understanding Atrial Fibrillation as a means by which to equip clinicians with the data and analytic tools needed to develop a better grasp of this arrhythmia’s full nature.     The book begins by providing a detailed explanation of atrial fibrillation’s causal mechanisms and builds its exploration from there. Working toward an up-to-date knowledge of the mapping and ablation of atrial fibrillation, its chapters assess the experimental data that has shaped current thoughts on the condition and then outline the best methods with which to interpret that rich but potentially difficult information. This revelatory new guide:     Explores hypotheses of multiple drivers and mechanisms co-existing in individual patients Addresses common misperceptions and inaccurate views about atrial fibrillation Describes the basic physiology of atrial fibrillation’s propagation and reentry Explores the various mechanisms and higher-order dynamics of fibrillation Discusses how to intervene and alter atrial physiology to prevent fibrillation Understanding Atrial Fibrillation is truly an invaluable resource for physicians, fellows, residents, electrophysiology lab staff, and all other practitioners involved in the diagnosis and treatment of atrial fibrillation.

Preface ix Acknowledgments xiii Part I: Building blocks of fibrillation 1 Excitation and propagation 1 Source-sink relationships 2 What determines source-sink balance? 3 Propagation and reentry 4 Requirements for reentry 4 What makes a circuit? 6 Source-sink balance and rotors 6 Wave length 8 Wave length, path length, and reentry 9 Restitution 10 Initiating reentry 11 Part II: Atrial fibrillation mechanisms 21 The evolution of current concepts 21 The mass hypothesis of atrial fibrillation 30 Principles of propagation: Implications for fibrillation 32 Focal rotors 52 Micro‐reentry 55 Fibrillatory conduction or multi‐wavelet reentry? 66 Location of atrial fibrillation drivers 76 Principles of propagation: Driver interactions in fibrillation 87 Part III: Working with incomplete information 93 Cardiac mapping 93 Sample density and atrial fibrillation 115 What should we do with the patient who comes to the lab tomorrow? Putting it all together (without “it all”) 128 Putting it all together: Atrial fibrillation in three questions 132 Appendix A: Calculating probability in a random walk 135 Appendix B: Dominant frequency analysis 137 Appendix C: A stupid idea, but a learning opportunity 143 References 149 Index 161