Afzal Sohaib - Decoding Cardiac Electrophysiology: Understanding the Techniques and Defining the Jargon

To the uninitiated, there is a perceived mystique about cardiac electrophysiology (EP) that often acts as a barrier to an even rudimentary understanding of EP procedures. Unhelpfully, this view of EP is not infrequently perpetuated by electrophysiologists themselves, with most apparently communicating in a language indecipherable, even to the seasoned general cardiologist. The purpose of this book is to simplify this jargon, and decode it into terms to allow newcomers to the field to find their way among the world of EP.

Unlike other realms of cardiology such as imaging, angiography and structural intervention, which have an obvious visual element (a regurgitant valve, a narrowed artery, etc.), electrophysiology instead relies upon the interpretation of electrical signals and the manner in which they propagate throughout the cardiac tissue. Since electricity itself cannot be physically visualised in real time, its presence and course through various cardiac structures instead needs to be inferred by the detection of electrical signals at various intra-cardiac sites. The direction and pattern of electrical wavefronts through tissue is determined by the timing of electrical signals in relation to each other, the surface ECG and/or a stable reference signal. For this reason, the language of electrograms needs to be comprehended before electrophysiological procedures can make sense. Fortunately, like any language, there are key fundamental principles and concepts which will aid the interested student in understanding and eventually becoming proficient in this language. This chapter focuses on describing these key concepts. Subsequent chapters will then apply these principles to the treatment of various commonly treated conditions.

Decoding the Jargon and Beyond the Basics

Electrophysiologists have a tendency to very quickly slip into using jargon. For this reason throughout the book, we have highlighted commonly used terms and described them in decoding the jargon boxes. Each chapter is structured so that the core concepts are the main focus and some of the more complex concepts are discussed in sections entitled beyond the basics towards the end of each chapter.

Before exploring some of these fundamental concepts it is useful to have an overview of the range of procedures which happen in the electrophysiology laboratory and the rest of the book will deal with each of these areas in detail. Procedures can be divided into standard EP and complex EP. This is an oversimplification and often what is classified as standard can be very complex and vice versa, but it is a useful way to orientate oneself, and these categories are frequently used by various bodies involved in overseeing electrophysiology [].

Standard EP usually refers to procedures which can deal with arrhythmias frequently from the right sided circulation and includes AV node ablation , AV nodal re-entry tachycardia (AVNRT), typical atrial flutter , and ablation of accessory pathways . These often can be done with a relatively simple arrangement of catheters and fluoroscopy. The risks are usually at the lower end, and procedure duration is usually at the lower end of the spectrum for electrophysiology procedures.