PARTE 1 LO BÁSICO

La primera parte cubre lo básico del ECG. La mayoría de los cuadros se presentan como material de nivel 1. Cualquiera que trate con ECGs debería conocer extremadamente la información de esta parte. Si usted es un profesional clínico con amplia experiencia, usted puede filtrar la información, pero no debería saltársela completamente. Asegúrese que usted entiende el material en profundidad andtes de pasar a la parte 2.

NOTA

Electrocardiografía pediátrica no se cubre en este libro debido a la extensa cantidad de material requerido para cubrir este tema. Se ruega al lector que se remita a libros específicos sobre electrocardiografía pediátrica.

Como leer un ECG

La mayor parte de este libro está orientado hacia el desglose de varias secciones del ECG y sus complejos. Los capítulos le enseñan lo que representa cada parte del ECG y sus anomalías correspondientes.

PART 1 The Basics Part 1 covers ECG basics. Most of the boxes are presented as Level 1 material. Anyone dealing with ECGs should be extremely familiar with the information in this part. If you are an experienced clinician, you can skim over the information but should not skip over it completely. Make sure that you understand the material thoroughly before going on to Part 2. NOTE Pediatric electrocardiography is not covered in this textbook due to the extensive amount of material required to cover this topic. The reader is referred to a textbook on the specific subject of pediatric electrocardiography. How to Read an ECG The majority of this book is geared toward breaking down the various sections of the ECG and its complexes. The chapters teach you what each part of the ECG represents and the respective abnormalities. Each section covers the pathology associated with a wave or interval of the ECG by using a problems-oriented approach that consists of examining the list of possible causes for a pathological wave or interval and determining how these relate to the other complexes. This list of possible causes is called the differential diagnosis. As you review the ECG, look at each wave and interval and create lists of abnormalities that you find in them. You will then have several lists. Find out what diseases or syndromes are common to all of those lists; that disease or syndrome will be, with almost complete certainty, the diagnosis. Before you start the book, we would like to offer the following steps to guide you in ECG interpretation. These steps will become second nature after review and use. Don’t worry if you are unfamiliar with some of the terminology—you will become familiar with it when you read the chapters. The most important task now is to develop a logical approach to examining and interpreting the ECG. You can adjust this system, as you need to, to match your particular style.

1. Get a general impression of what is going on and keep it foremost in your mind.

Look at the ECG for a few seconds and see what strikes you as the most important detail. Is it ischemia, arrhythmia, electrolyte problems, pacer problems, or something else? Don’t let the details overwhelm you—instead, form the big picture first and keep it in your mind as you move on to interpret the ECG. Eventually, you will learn how to break down the ECG and methodically derive an

interpretation.

2.   Look at the ECG sequentially and in minute detail. This is the second concept that involves all of the steps below. When starting out, try to use an ECG that contains a rhythm strip at the bottom that correlates with the leads above—it will make your life much easier. Look at the beats. If they look different, break them down and figure out which are the normal beats and which are the abnormal beats. Look at the normal beats first to determine your intervals, axis, blocks, etc. Then look at the abnormal beats and figure out what is causing them. Are they PACs, PVCs, aberrant conduction, paced beats, or something else?

3.   What is the rate? •   Is it fast or slow? •   If it is irregular, what is the range? •   What are the intervals: PR, QRS, QTc, PP, RR? •   Are there irregularities in any of the intervals, for example, PR depression? 4.   What is the rhythm? •   Is it fast or slow? •   Regular or irregular? •   Grouped or ungrouped? •   Can you see P waves? Are they all the same? •   Is there one-to-one conduction of the P waves to the QRS complexes? •   Wide or narrow? 5.   What is the axis? •   What quadrant does it fall into? •   What is the isoelectric limb lead? •   Where is the transition zone in the precordials? •   Calculate the exact axis. (Advanced clinicians should also calculate the P, T, and ST axes.) •   Does the exact axis tell you anything? 6.   Is there any evidence of hypertrophy? •   Left atrial? •   Right atrial? •   Biatrial? •   Left ventricular? •   Right ventricular? •   Biventricular? •   Left or right strain pattern? 7.   Is there any evidence of ischemia or infarction? •   Are there regional T wave abnormalities? •   Are there regional ST segment abnormalities? • Are there regional Q waves? 8.   How can I put it all together? Think of all the findings and try to come up with a common theme to the differential diagnosis that you have developed. Think of everything and overlook nothing. Be sure to consider the rate, rhythm, axis, hypertrophy, interval abnormalities, blocks, and ST and T wave abnormalities. 9.   Can I put it all together with my patient’s signs and symptoms? Do the diagnosis and findings on the ECG make sense with the patient’s presenting signs and symptoms? Can the ECG be a presentation of a problem or the cause of some pre-existing condition? Ask yourself, “How can I use the information to adequately treat the patient?” 10.   What is my final diagnosis? List your final single diagnosis or your abbreviated list of differential diagnoses. In closing, don’t forget that it takes time to learn to interpret ECGs. Some of the concepts we mention in the list above may be above your level now, but not for long! The more you use the book, the better you will become. Lastly, have fun! Life is short.