An ECG waveform is composed of the following:
- Isometric line – starting point of a rhythm, the heart is not contracting
- P wave – happens during atrial contraction
- QRS wave – occurs ventricular contraction
- T wave – repolarization
When interpreting a rhythm, you have to keep in mind that there are a couple of criteria that you have to take into consideration. There are five important tips before jumping to conclusions. You don’t easily say, “That’s atrial fibrillation, or an atrial flutter, or a ventricular tachycardia, or a bundle of branch blocked.”
Remember that correct interpretation is crucial to appropriately address the medical situation of a client. Jumping to conclusions without properly assessing a client can lead to further injury.
How is this done?
First, you have to go through the five-system step. Then, eliminate the wrong answers using the method of exclusion.
By utilizing Mike’s five-system step, you will be able to accurately interpret EKG rhythms in 15 seconds or less. Yes, it is possible. You just have to know what to do and how to do it.
The Five-System Step
Step 1: Determine any P waves. Once you have, you can move on to the next step.
Step 2: Point out if QRS waves are present. Atrial depolarization causes blood to go down into the ventricles which leads to swelling. Ventricle swelling causes contraction which results in the presence of a QRS wave.
Step 3: Measure the PR intervals. PR interval is basically the line that separates the beginning of a P wave to the beginning of a QRS wave. By measuring the PR interval, you would know how much time it took for contraction to be transferred from the atrium to the QRS wave. The main goal of measuring the PR interval is to recognize a block or a breakdown between conduction systems.
Remember, normal PR interval is below five EKG boxes and every box represents 0.04 seconds. Anything longer than five boxes would mean that the atriums are not contracting in the succinct amount of time for the QRS to receive.
Step 4: Figuring out the rate. The rate is counting the beats per minute that affect the contraction of the QRS wave. You can do this by counting how many times the peak of the QRS interval, which is the R wave, appeared in a six-second strip. Although this is not the most accurate way to count a rhythm or a rate, it is the easiest. It can help you recognize bradycardia (rate is less than 60), tachycardia (rate is greater than 100), or a normal rate. You’ll be able to say that the rate is not rhythmic by identifying long pauses in between beats.
Step 5: Classifying a rhythm. Here, you have to consider the following:
- Is it regular or irregular?
- Is it contracting at certain amounts of beats? Are they concise?
- Does it happen altogether then slow down?
- Is it erratic?
You’ll see this in atrial fibrillation which is an episode of erratic heartbeats.
To gain further insight into getting an accurate interpretation of EKG rhythms, you can go to part 2 of the discussion.