EKG Interpretation in 3 Easy Steps: An Overview – Part 3

In our part 3 of EKG rhythm interpretation, you will get a quick rundown on the anatomy of the heart and how a typical rhythm malfunctions, progressing to the different types of heart rhythm abnormalities.

The Heart Set-Up

First, we go to the basics – the anatomical parts of the heart mainly involved in transmitting impulses.

  1. Left and right atriums and the left and right ventricles – functioning as the pumping stations of the heart
  2. Tricuspid and bicuspid valves – separates the upper and lower chambers of the heart
  3. Septum – found in between the left and right heart chambers of the heart
  4. SA node and AV node – electrical conductors
  5. Intranodular/Internodal tracts – also known as Bachmann’s bundle
  6. Bundle of His – responsible for transmitting impulses coming from the atrioventricular node to the heart ventricles
  7. Bundle of branches – transmits cardiac activity from the Bundle of His to the Purkinje fibers
  8. Purkinje fibers – responsible for ventricular contraction or the squeezing of the ventricles

The abovementioned parts of the heart are how you expect the heart to function and react. By the way, the SA node has 60 to 100bpm while the AV node has 40 to 60bpm. So, that’s how the heart routinely works.

Heart Rhythm Abnormalities

We have broken down the heart into three parts to give you a clearer view of the irregularities that happens in each section.

  1. Atrium

Here, you have your atrial fibrillation and your atrial flutter. Here’s how you can easily distinguish the two:

  • Atrial Fibrillation. Here, the faulty SA nodes fire rapidly all over the place, kind of like a Fourth of July in your heart or like a machine gun that shoots electrical charges all over the right atrium. Thankfully, the AV node is there to keep the pulses from getting into the ventricles. The AV node serves as your border control that blocks all the erratic and unnecessary impulses to enter the ventricles.

Impulses created by atrial fibrillation: 350 – 650bpm

How it looks at an EKG strip: “Fibbing out” with no P waves

  • Atrial Flutter. This irregularity can be compared to someone lighting up a box of fireworks and have left it inside the left and right atriums; affecting the pacemaker cells. Compared to atrial fibrillation, atrial flutter acts succinctly showing up as saw-tooth figures on an EKG strip. You can think of this as someone sawing wood, then woodchips and wood shavings flutter off in different directions.

Impulses created by atrial fibrillation: 250 – 350bpm

How it looks at an EKG strip: Saw-tooth with intervals of normal QRS waves

  1. AV Node

In your AV node, you have the bundle branch blocks (BBB) which basically refers to the bundle branches extending from the Bundle of His (looks like viper fangs); one of two branches can be blocked for whatever reason. In the BBB, you can have:

  • Right bundle branch block
  • Left bundle branch block
  • 1st-degree block
  • 2nd-degree block
  • 3rd-degree block (deadliest among the three degrees)

That’s just an overview. Detailed discussions of these bundle branch blocks are available in other lectures.

  1. Ventricles

It is in the ventricles where the two deadliest rhythms are occurring – ventricular fibrillation (V-Fib) and ventricular tachycardia (V-Tach). In hindsight, the ventricles squeeze or contract to provide oxygen to the body; the left ventricle pushes the afterload (blood) into to the body through the aorta.

Therefore, if the ventricle is not squeezing, you’re basically suffocating yourself; also known as ventricular flutter. Clients who present with ventricular fibrillation and ventricular tachycardia will have an altered level of consciousness. What do clients manifest?

  1. The alert and oriented is zero, so clients are usually unresponsive.
  2. If they are awake, they will feel extremely lightheaded due to decreased oxygen perfusion.
  3. They will be very anxious and disoriented.

To address the urgency of V-Fib and V-Tach, healthcare practitioners usually result to:

  1. Shock administrations with chest compressions
  2. Pharmacological drugs (i.e., epinephrine) that realigns your ventricular rhythms to normal rhythms

So that’s just an overview of what happens in the heart if in case it goes out of hand. Now, for our next lesson, we’ll be having a comprehensive discussion about atrial fibrillation and atrial flutter.

EKG Rhythms: Accurate Interpretation in 3 Easy Steps Pt 2

Whether you’ve been out of school for 30 years or more, or finishing your nursing school but still have no idea how to do proper EKG interpretation and how the concepts work, this is for you.

For anyone of you who has trouble understanding the basics, Mike has made it uncomplicated to comprehend and remember the fundamentals of EKG rhythms. Guaranteed, you’ll be able to interpret EKG rhythms in three minutes or less!

Before getting into the core of this topic, let’s focus first on what an EKG is.

EKG is short for electrocardiogram; which simply means a picture of your heart or basically the activities of your heart.

The four-bedroom suite

In SimpleNursing.com, we make sure that you are able to relate every concept to what you are already familiar with. With EKG, it’s the heart. Consider your heart as a four-bedroom suite because it has four chambers and every chamber is divided by valves. These valves are like the French doors to your heart. 

The atriums

So, in the heart, there are upper rooms called atriums. The atriums are small upper chambers of the heart. These chambers, you can call refer to them as the attic or the guest rooms, they are the first ones to squeeze blood to the other chambers because the atriums are the rooms that first takes in the blood from the veins.

Remember: In all the chambers of the heart, the atriums are responsible for receiving unoxygenated blood which is blood that already circulated the body and have depleted oxygen supply.

The ventricles

Now, from the atriums, blood gets pushed down to the other chambers like the master’s bedroom or the living room. These chambers that are located below the atriums are referred to as the ventricles. 

EKG application

By keeping in mind the concept above, you can easily determine how the heart works in an EKG strip. What does each wave represent?

  • P wave – appears first, signifies your atriums pumping blood
  • QRS wave – next to appear, signifies your ventricles squeezing blood
  • T wave – relaxation or repolarization of the ventricles

So this set-up is like the principle in physics: what goes up must come down. That’s basically what you’ll see on your EKG paper.

Zooming in 

Medically speaking, the “atrial squeeze” seen on your P wave is called atrial depolarization. Depolarization is simply sending a charge away by pushing the blood out of the heart. Once the blood goes into ventricles, it takes all the blood in, making those chambers swell. The ventricles need to squeeze the blood out of their chambers which is basically your ventricle depolarization. 

After the ventricles have depolarized blood out of it chambers, it needs to re-polarize or relax. So basically your T wave is medically referred to as ventricular repolarization. 

Oxygen distribution

Here’s a quick question. Before the left ventricle has squeezes blood out of its chamber and into the aorta, where should blood go first to be oxygenated before it gets distributed to the different parts of the body?

So, here’s how the blood flows in the heart:

The right atrium receives unoxygenated blood then in pumps the blood to the right ventricle. The right ventricle is expected to be big enough to get the necessary pressure to pump the blood into the lungs. From the lungs, as we inhale oxygen and exhale carbon dioxide, blood becomes oxygenated. Oxygenated blood from the lungs goes into the left atrium and finally, it gets pumped into the left ventricle. The left ventricle, being a big chamber, is basically responsible for squeezing oxygenated blood from its area into the aorta to the different parts of the body.


Quick recap

P wave – atrial depolarization

QRS wave – ventricular depolarization

T wave – ventricular repolarization

To apply what you now know, here’s a critical thinking question:

Why isn’t there a P wave repolarization on your EKG strip (“earthquake paper” as Mike likes to call it)?

There is actually P wave relaxation; however, it doesn’t appear on your EKG strip because the QRS wave is covering it.

That’s a little trivia for you.

So this is how the heart normally works. In the next segment, you will be able to learn what goes amiss in your heart conduction. There is still tons of nursing information in our SimpleNursing.com database. Aside from more EKG content, you can also drop by to check out on our wide variety of topics on anatomy and physiology, nursing fundamentals, and more.


EKG Rhythms: Accurate Interpretation in 15 Secs or Less Pt 1

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.