© Steve Allen/Brand X Pictures/Alamy Images
© Steve Allen/Brand X Pictures/Alamy Images
One of the most important skills for any clinician to master is the ability to recognize and evaluate a rhythm strip. This information is as basic as knowing how to use a stethoscope. However, as our reliance on newer and more advanced technology has increased, our basic clinical and diagnostic skills have begun to deteriorate.
Arrhythmia recognition is, by its very nature, cloaked in objective criteria. We need these criteria to differentiate between the various rhythm abnormalities and to allow us some objectivity when assigning the various treatment strategies. However, if objective criteria were the only variables involved in evaluating a rhythm, computers would have taken over the job of interpreting ECGs and rhythm strips long ago. But, as we all know, computer assisted interpretation has pretty much been unreliable to date. Why? Because arrhythmia recognition is primarily an art. Computers don’t do well with art.
An appreciation of art requires deep, thoughtful study and mastery of a subject and that requires time. However, in our busy, hectic lives, most of us cannot dedicate that much time and effort to just this one aspect of clinical practice. We barely have enough time to keep up with all of the new information, let alone going over the basic information. In addition, our clinical instructors and educators have to spend more and more time on paperwork and securing reimbursement, and they, therefore, have less and less time to devote to teaching.
So, we rely on specialists to give us a final interpretation for our patient’s strips and ECGs. However, here is an interesting fact: Historically, many cardiologists failed the boards because of an inability to interpret ECGs. Training difficulties apply to them as well.
Furthermore, despite the new resurgence of the acceptance of the generalized terms supraventricular and wide-complex tachycardias by the American Heart Association, the bottom line is that you still are expected to understand the rhythms themselves and their appropriate treatment strategies. This can be a tough assignment, especially when the supraventricular tachycardia presents with wide QRS complexes. In addition, just as our ability to diagnose complicated arrhythmias has expanded, so too has our ability to provide focused treatment through the use of specialized equipment, more targeted pharmaceutical agents, and more specific treatment protocols. As you can imagine, focused treatments provide better outcomes.
Our old ideas about arrhythmias have also changed with the onset of electrophysiology as a medical subspecialty. Newer techniques bring newer insights and treatment. As educators, we need to come face-to-face with this new mindset and come up with new and creative approaches to medical education and training. Hopefully, this book is just one of those small steps.
We can no longer rely on books that present just a few isolated facts and give you a bunch of strips with no guidance as to how to interpret them. We need to understand the why’s and how’s and be able to distinguish between the various possibilities. We cannot afford to fall back on traditional systems of learning arrhythmia recognition for the patient’s sake and because of our ever-increasing problems—a continuously expanding knowledge base, a shrinking time pool to pursue medical education, and medical malpractice.
In order to understand and interpret rhythm strips and ECGs thoroughly, we need to approach the material with three main objectives in mind: 1) We need to understand the objective criteria for each arrhythmia; 2) We need to fully understand the mechanisms involved and the subtleties that can develop within that one rhythm category and in any one patient; 3) We need to be able to put our electrocardiographic findings together with the history, physical exam, and laboratory data to arrive at the correct diagnosis for our patient. ECGs and rhythm strips do not live in a vacuum. In this book, we will meet these objectives head on.
We will provide you with the objective criteria that are particular to that one rhythm and then we will discuss the mechanisms and subtleties of each rhythm abnormality. In addition, we will give you various examples of each of the arrhythmias so that you can see these subtleties in action. We will try to provide you with examples that cover the full spectrum of the clinical presentation, including real-life strips that are not “pristine.”
At the end of each chapter, we will provide you with a synopsis of the rhythm, which basically organizes everything in a nutshell for you. This will be very helpful when you just want a quick review or when you just need to look up some quick facts about the rhythm.
Being able to interpret the arrhythmia without knowing the potential clinical causes is not a very healthy way to approach arrhythmia recognition. As such, we are providing a differential diagnosis block at the end of each of the chapters to point you in the right clinical direction. Please note that these differential diagnosis boxes are not all-inclusive but contain the major culprits in which the rhythm abnormality is typically found.
The chapters conclude with a review containing fill-in-the-blank, multiple-choice, and true and false questions. The purpose of these questions is not to provide you with unanswerable challenges but to re-emphasize the important take-home messages of the chapter.
Each section ends with a review test in which we provide you with some unknowns. You should spend the time to solve each of the rhythm strips and to understand them. Once you have completed your evaluation, you can turn to the answers for confirmation and further discussion. This is a feature that we feel will strengthen your understanding by providing you with some “individualized” instruction about each of the strips. In other words, we will work through each strip with you instead of just giving an answer without explanation.
The book ends with two of my favorite features—a chapter on putting it all together and two final tests. I like to think of these two features as working together to put the finishing touches on your studies. The chapter on putting it all together is geared towards strengthening the art of interpretation to the maximum. In this chapter, we try to reinforce the need to evaluate all of the information at your disposal to interpret the rhythm. These sources of information include the history, physical exam, and laboratory data, as well as the ECG and the rhythm strip.
Many of you will be very upset that we did not include treatment strategies in this book. The reason that we did not present this information is that it typically takes about 2 to 3 years to bring a book from conception to print. Most of the information that you find in medical textbooks, including the references, is obsolete by the time the book hits the shelves. If not, it will be obsolete very shortly afterwards. The only thing more dangerous than a lack of information is wrong information. We encourage you to go on the Internet and review the latest treatment strategies for the various rhythms as you finish each chapter. This way, you will have the most current and up-to-date information available.
When I teach medical students physical diagnosis, they spend the first couple of weeks merely observing patients from afar. They are not to talk to or examine the patient. I only demand that they answer one simple question: Is the patient sick or not sick? They only have about 10 to 15 seconds to make up their minds, so that they cannot rationalize too much. Their decision has to be made from the gut, based on information that they gain through observation either consciously or unconsciously. It sounds complicated and yet students amaze me with how quickly they learn this task and how effectively they put these lessons to use. This internal decision maker is an innate part of us all and will never steer you wrong. All you have to do is develop it.
So what does this have to do with rhythm strips? Simple—we are going to use the same approach to learn arrhythmia recognition. The only way to learn arrhythmias is to look at thousands of them and answer the question, “sick or not sick.” Most findings are not as unique from person to person, but instead they vary from person to person and even within the same person at various times (kind of like fingerprints). If you only see one sample strip for each pathology but never see that picture-perfect example again in your life, you will never be able to diagnose it in your patient.
The complex language that is used in electrocardiography can be confusing and overwhelming. Most people buy an advanced textbook on arrhythmias, begin to read it, and then quickly give up. Sound familiar? You have to be very competent at electrocardiography and arrhythmia recognition to be able to understand the written word describing the possible variations. Most of us are visual learners. The simple way to learn about the rhythms, and the one that has been largely under- utilized, is to use extensive graphics and to show various examples of each abnormality in order to develop a feel for what you are looking at. After a while, you will begin to feel your gut telling you whether the patient is “sick or not sick.”
The process of learning to interpret rhythm strips is not unlike learning to throw a ball. You can read about the throw, the trajectories, the spin, and the accuracy, but unless you see a few balls thrown and throw hundreds or thousands yourself, you will never really learn know how to throw a ball. In the same way, you need to see hundreds of strips before you become comfortable. By the time you finish this book, you will be comfortable with the terminology and the concepts.
I have been asked by a few hundred students to teach them what they really need to know. I can sum up the answer in one short, concise statement: you need to know the changes that your specific patient presented you on their strip! You never know what will be important at any one point in your career; any one fact can cost the patient his or her life and will cost you countless hours of guilt, and possibly millions of dollars! Arrhythmia interpretation is the same whether you are an EMT, paramedic, nurse, resident, attending physician, or a cardiologist. You cannot learn just enough to get by. Does a resident need to know the changes of hyperkalemia that can lead to a lethal arrhythmia? Does a paramedic or nurse need to know that focal atrial tachycardia with block is associated with digoxin toxicity? To whom is it more important to know that a patient with a prolonged QT interval can develop torsade de pointes? It is important to you if you are the only one around at the time. Passing the buck to a higher level doesn’t work with arrhythmias because you may not have enough time to pass it!
In closing, I would like to state that you need to look at everything at your disposal and trust yourself when you are interpreting a rhythm strip. Don’t let anyone talk you out of something that you know is true. Just smile at them and do what is best for the patient. You will not go wrong. Remember that an expert is someone who knows one more fact than you do. However, that one fact may not be relevant to your case so you may be the true expert!
—Tomas B. Garcia, MD
Learning how to make sense of rhythm strips and electrocardiograms is extremely daunting. It requires a lot of time, effort, and a very open mind. Since I am my father’s son, I grew up with a pair of unsharpened ECG calipers instead of a baby rattle. And when I started school, I used an ECG ruler to make straight lines. I remember listening to adults discussing ECGs from an early age and listened to many a lecture in our house as my father taught medical housestaff and ancillary personnel.
As I matured, I struggled like all beginners, and I have suffered through the various lessons from the school of hard knocks in order to learn what works and what doesn’t. This background has provided me with a strong foundation and given me a distinct point of view because I was recently in your shoes walking the same road that you are now walking. In the Beginner’s Perspective sections, I’ve put together some of the things that helped me along the way and will hopefully provide you with a roadmap to make your journey easier.
Occam’s razor is a scientific principle which states that if you are dealing with competing hypotheses, the simplest one (the one with the fewest assumptions) is usually the correct one. In other words, nature is extremely efficient and takes the simplest route to solve a problem. The same is true of the principles of arrhythmia recognition. Despite the fact that every heart gives rise to its own intrinsic and individualized morphological appearance, the heart is ruled by certain underlying principles. Understand the mechanisms, and you understand the pathology.
We are wholeheartedly committed to making the process of understanding arrhythmia recognition as easy as possible. Rote memorization of the criteria is not as important as understanding why things occur. In order to do this, you should strive for understanding the mechanisms involved. Once you figure it out, you will never forget it.
The more I learned, the more I realized the wisdom of those simple concepts, and the more I focused on the lessons I was entrusted to safeguard by some very distinguished educators. Those ECG “secrets,” which are actually some very fundamental principles of medicine, are what I humbly hope to pass on to you.
—Daniel J. Garcia