10 Steps to Learn ECG Interpretation
Learning the art of ECG interpretation requires intellect, commitment, effort and — perhaps most importantly — an organized approach.
I have spent thousands of hours (yes, thousands) looking at 12-lead ECG tracings, studying ECGs for the cardiology boards, interpreting ECGs for direct patient care, and developing ECG tutorials and quizzes for Learn the Heart.
Assuming that most of you reading this blog do not have that much time, allow me to share what I have discovered in my years teaching ECGs to make the process simpler — and maybe even enjoyable.
ECGs Made Easy?
Learning all of ECG interpretation is going to take time and it is not quite so easy. To be proficient, it will take effort. Some memorization and pattern recognition will be required. The more you see, the more you will remember. Having a pair of calipers is helpful.
Step 1. Learn the Basics of a 12-lead ECG Tracing
Knowing the basic parts of an ECG tracing will lay a good foundation for everything else that is to come. The different waves, complexes and intervals need to be ingrained in your brain. How many seconds is a full ECG tracing? How much time does each big box and each little box represent?
This is not the time to learn about the different P-wave morphologies that occur with atrial enlargements and ectopic atrial rhythms — but rather, it is the time to learn what the normal P wave looks like and what it represents. It’s a similar concept for the other parts of the ECG.
The Learn the Heart ECG Basics module contains detailed articles on various waves, segments, intervals and more.
Step 2. Determine Heart Rate on the ECG
To determine whether bradycardia, a normal heart rate or tachycardia is present requires the knowledge to calculate the heart rate on the ECG. Remember to apply these techniques to both the atrial rate, which is measured by the rate of the P wave, and the ventricular rate, which is measured by the rate of the QRS complex.
Read Determining Rate.
Step 3. Determine Axis on the ECG
The axis on the ECG can give a clue to many different pathologic states. Unless you are going into electrophysiology as a career, the only axis that you need to measure is that of the QRS complex.
Know the causes of left axis deviation, right axis deviation and when the axis is indeterminate (northwestern). Also, know the quick shortcuts to determine the axis.
Read Determining Axis.
Step 4. Learn Abnormal Heart Rhythms
Learning a normal sinus rhythm was taken care of in Step 1. Now, it is time to learn the below rhythms. Review multiple examples of each in the individual ECG Reviews sections below.
- Atrial Fibrillation ECG Review
- Atrial Flutter ECG Review
- Atrioventricular Nodal Reentrant Tachycardia (AVNRT) ECG Review
- Atrioventricular Reentrant Tachycardia (AVRT) ECG Review
- Ectopic Atrial Rhythms ECG Review
- First-Degree Atrioventricular (AV) Block ECG Review
- Idioventricular Rhythms ECG Review
- Junctional Rhythms ECG Review
- Multifocal Atrial Tachycardia (MAT) ECG Review
- Second-Degree Atrioventricular (AV) Block Type I (Wenkebach) ECG Review
- Second-Degree Atrioventricular (AV) Block Type II ECG Review
- Sinus Arrhythmia ECG Review
- Sinus Bradycardia ECG Review
- Sinus Tachycardia ECG Review
- Third-Degree Atrioventricular (AV) Block ECG Review
- Ventricular Tachycardia (VT) ECG Review
- Wandering Atrial Pacemaker (WAP) ECG Review
Step 5. Learn Chamber Hypertrophies and Bundle Blocks
Learning chamber hypertrophies and bundle blocks can be difficult. Atrial enlargements are not too difficult, but the criteria for left ventricular hypertrophy can be overwhelming. In my opinion, there is no need to memorize them all, but rather just the main two or three.
With left and right bundle branchs, the “bunny ears” are easy to spot in right bundle branch blocks, although not always present. Don’t forget to learn what a non-specific interventricular conduction delay looks like, as well.
- Bifascicular Block ECG Review
- Left Anterior Fascicular Block (LAFB) ECG Review
- Left Atrial Enlargement (LAE) ECG Review
- Left Bundle Branch Block (LBBB) ECG Review
- Left Posterior Fascicular Block (LPFB) ECG Review
- Left Ventricular Hypertrophy (LVH) ECG Review
- Poor R Wave Progression ECG Review
- Right Atrial Enlargement (RAE) ECG Review
- Right Bundle Branch Block (RBBB) ECG Review
- Right Ventricular Hypertrophy (RVH) ECG Review
- Trifascicular Block ECG Review
Step 6. Learn Acute MI and Ischemic ECG Findings
This is the fun part of ECG interpretation. Some of the acute MI ECG findings, such as anterior ST segment elevations and inferior ST segment elevation MIs, are obvious. The tough part is identifying the more subtle ECG changes.
Know when ST segment elevation is due to ischemia and when it is due to other causes, including left ventricular aneurysm or left ventricular hypertrophy. Likewise, know when ST segment depression is due to digoxin ECG changes.
- Anterior Wall ST Segment Elevation Myocardial Infarction (MI) ECG Review
- Inferior Wall ST Segment Elevation Myocardial Infarction (MI) ECG Review
- Posterior Wall Myocardial Infarction (MI) ECG Review
Step 7. Learn the Everything Else Including Atypical ECG Findings
Some repetition and memorization is required. The list of things that go into this category is long. Review the list below.
- Arrhythmogenic Right Ventricular Dysplasia (ARVD) ECG Review
- Atrial Septal Defect (ASD) ECG Review
- Brugada Syndrome ECG Review
- Dextrocardia ECG Review
- Digoxin Effect ECG Review
- Early Repolarization ECG Review
- Hypercalcemia ECG Review
- Hyperkalemia ECG Review
- Hypertrophic Obstructive Cardiomyopathy (HOCM) ECG Review
- Hypocalcemia ECG Review
- Hypokalemia ECG Review
- Hypothermia ECG Review
- Left Ventricular (LV) Aneurysm ECG Review
- Limb Lead Reversal ECG Review
- Lown-Ganong-Levine Syndrome ECG Review
- Low Voltage ECG Review
- Neurologic Insult ECG Review
- Pericarditis ECG Review
- Prolonged QT Interval ECG Review
- Pulmonary Embolism ECG Review
- Wellens’ Syndrome ECG Review
- Wolff-Parkinson-White (WPW) ECG Review
Step 8. Quiz, Quiz, Quiz and Review, Review, Review
Take the Learn the Heart ECG Quizzes and Cases, then review once again, or as many times as you’d like, when you identify a gap in your knowledge. You can never look at too many 12-lead ECG tracings. In real life, you see full 12-lead ECG tracings — so that is how you need to test yourself.
Step 9. Review ECGs in Real Patient Case Scenarios
Whether you are a medical student in clinical rotations, an EMT or an internist in practice, or another health care professional, looking at the ECGs that you will encounter in everyday practice is important. See how the ECG fits the clinical scenario. Sometimes the best way to remember an ECG finding is to associate it with an interesting case that you experienced personally.
Alternatively, you can practice with ECG Cases, like the examples in the Learn the Heart ECG Library — online or in a textbook — in which a patient scenario is presented and the ECG that goes along with it is revealed.
Step 10. Teach Others How to Read an ECG
I have learned the most about ECG interpretation by developing content for Learn the Heart and teaching ECG courses in person. If you can put yourself in a position to teach students or your colleagues about ECGs, you will solidify your skills tremendously.
The Practice of Medicine – Never Stop Learning
Keep reviewing. One day, you will stop and think, “Wow, I think I get it.” Follow Learn the Heart and read the articles regularly. This will keep things fresh in your mind and will even introduce you to rare ECG tracings. – by Steven Lome, DO, RVT