ECG Interpretation For Beginners. Different Leads and Axis Deviation

Summary

In this educational transcript, Dr. Camka discusses the intricacies of interpreting EKGs, emphasizing the importance of the 12-lead system for capturing the heart's electrical rhythm from multiple angles. The conversation delves into the concept of axis deviation, explaining how it reflects the average flow of electricity through the heart and how it can indicate conditions like left or right ventricular hypertrophy. The quadrant method is introduced as a simplified approach to determine axis deviation by focusing on the QRS complex in leads I and AVF, offering practical insights for medical professionals.

Takeaways

• 📊 EKGs provide a snapshot of the heart's electrical rhythm from 12 different angles, aiding in comprehensive understanding of heart function.
• 🧠 The 12 leads are categorized into two sets: precordial (chest) leads and limb (green) leads, each offering insights into different portions of the heart's electrical activity.
• 🔍 Axis on an EKG represents the average flow of electricity through the heart, with a normal heart's flow directed downwards and to the left.
• 📈 The Quadrant Method simplifies axis determination by focusing on the QRS complex in leads I and AVF, allowing for quick identification of axis deviation.
• 🠖 Right axis deviation is indicated by a negative QRS complex in lead I and a positive QRS complex in lead AVF, commonly associated with right ventricular hypertrophy.
• 🠗 Left axis deviation is indicated by a positive QRS complex in lead I and a negative QRS complex in lead AVF, often seen in left ventricular hypertrophy due to long-term hypertension.
• 💔 Ischemia can affect the axis by causing the mean vector to deviate away from the infarct, alongside other conditions like hypertrophy.
• 🔎 EKG analysis should always include the determination of rate, rhythm, and axis to ensure a comprehensive assessment of the heart's electrical activity.
• 👨‍⚕️ Medical professionals like Dr. Camka use EKGs to diagnose and monitor various heart conditions, including hypertrophy and ischemia.
• 📚 Understanding the different leads and their corresponding views of the heart (anterior, posterior, lateral) is crucial for accurate EKG interpretation.
• 🛠 Practicing with actual 12-lead EKGs helps in applying the concepts of axis determination and identifying potential heart conditions in real-world scenarios.

Q & A

What is the primary purpose of an EKG?

The primary purpose of an EKG is to capture a single snapshot of the heart's electrical rhythm from 12 different angles, which helps in understanding the heart's function and detecting any abnormalities.

Why is it important to have 12 leads in an EKG?

Having 12 leads in an EKG is important because it allows for a comprehensive view of the heart's electrical activity from multiple angles, ensuring that no potential issues are missed. Each lead provides information about different portions of the heart, such as the anterior, posterior, and lateral regions.

What does the term 'axis' refer to in the context of an EKG?

In the context of an EKG, 'axis' refers to the average flow of electricity through the heart. It is a measure that indicates the overall direction of the heart's electrical activity and can be used to identify certain cardiac conditions.

What is the normal range for the heart's axis?

The normal range for the heart's axis is between 0 degrees and minus 90 degrees. This reflects the typical leftward and downward direction of the heart's electrical activity in a healthy individual.

What conditions can lead to right axis deviation on an EKG?

Right axis deviation on an EKG can be indicative of conditions such as right ventricular hypertrophy, where the right ventricle becomes enlarged, often due to increased pressure in the pulmonary artery. This is commonly seen in patients with pulmonary hypertension.

What does left axis deviation on an EKG suggest?

Left axis deviation on an EKG suggests that the average electrical activity of the heart is deviated to the left. This can be commonly seen in conditions like left ventricular hypertrophy, which is often associated with long-standing hypertension.

How can you determine the axis using the quadrant method?

The quadrant method for determining axis involves examining the QRS complex in two specific leads: lead I and AVF. If the QRS complex is positive in lead I and negative in AVF, the axis is somewhere between these two leads, indicating left axis deviation. Conversely, if the QRS complex is negative in lead I and positive in AVF, the axis lies in the opposite quadrant, indicating right axis deviation.

What are some other factors besides hypertrophy that can affect the heart's axis?

Besides hypertrophy, several other factors can affect the heart's axis, including ischemia, which can cause the mean vector to deviate away from the infarct, as well as other cardiac and non-cardiac conditions that influence the heart's electrical activity.

What are the two sets of leads in an EKG and how do they view the heart?

The two sets of leads in an EKG are the precordial (chest) leads and the limb leads. The precordial leads, represented by purple, view the heart from the horizontal axis, while the green limb leads view the heart from the frontal axis. This allows for a 3D understanding of the heart's electrical activity.

Which leads should be focused on when determining the axis in an EKG?

When determining the axis in an EKG, the focus should be on the limb leads, specifically lead I and AVF, as these leads provide information on the frontal plane of the heart's electrical activity, which is essential for axis determination.

How does the axis deviation relate to the heart's electrical activity?

Axis deviation, whether right or left, reflects a change in the average direction of the heart's electrical activity. This deviation can indicate underlying cardiac conditions or abnormalities that are affecting the heart's normal electrical conduction pathways.

Outlines

00:00

📊 Understanding 12-Lead EKG and Cardiac Axis

This paragraph delves into the intricacies of interpreting 12-lead electrocardiograms (EKGs) with a focus on comprehending the heart's electrical rhythm through various leads. It explains how the EKG represents a snapshot of the heart's rhythm from 12 different angles, akin to a chest x-ray from the lateral and frontal planes. The discussion introduces the concept of cardiac axis, which is the average flow of electricity through the heart, typically leaning down and to the left. The Quadrant Method is introduced as a simplified approach to determine the axis by examining the QRS complex in leads I and AVF. The implications of right and left axis deviation are also discussed, relating them to conditions such as left ventricular hypertrophy and long-standing hypertension.

05:03

🩺 Axis Deviation Causes and Clinical Implications

This paragraph continues the exploration of axis deviation in EKG readings, highlighting that while hypertrophy is a common cause, several other factors can influence the cardiac axis. It emphasizes the importance of considering ischemia, which can cause the mean vector to deviate away from the infarct. The segment also stresses the necessity of determining the rate, rhythm, and axis on every EKG to ensure accurate clinical assessment. The discussion provides practical insights into how different EKG findings, such as right axis deviation linked to right ventricular hypertrophy and pulmonary hypertension, can guide clinical diagnosis and patient management.

Keywords

💡EKG

EKG, or Electrocardiogram, is a non-invasive test that records the electrical activity of the heart. It provides a snapshot of the heart's electrical rhythm from 12 different angles, which helps in diagnosing various heart conditions. In the video, the EKG is central to understanding the heart's electrical activity and is used to determine the heart's axis and identify any potential abnormalities.

💡Leads

In the context of EKG, leads are the electrical pathways that connect the patient to the EKG machine. There are 12 leads that are used to capture the heart's electrical activity from different angles. Each lead provides a specific view of the heart's electrical activity, allowing for a comprehensive analysis of the heart's function. The script discusses how these leads are used to understand the heart's electrical flow and determine the heart's axis.

💡Three-Dimensional Structure

The term 'three-dimensional structure' refers to the complex, 3D shape of the heart, which is represented in a 2D format on an EKG. The challenge lies in interpreting the 2D EKG to understand the 3D electrical activity of the heart. The script emphasizes the importance of considering the 3D nature of the heart when analyzing EKGs to ensure a comprehensive understanding of the heart's condition.

💡Axis

Axis in the context of an EKG refers to the average direction of the heart's electrical activity. The normal heart axis leans down and to the left, which is reflected in the average flow of electricity. Deviations from this normal axis can indicate various heart conditions. The script explains how to determine the axis using the EKG and the significance of axis deviation in diagnosing heart problems.

💡Quadrant Method

The Quadrant Method is a simplified approach to determine the heart's electrical axis using the EKG. It focuses on the QRS complex in two specific leads, Lead I and Lead AVF, to identify in which quadrant the electrical vector lies. This method helps in quickly identifying whether there is a right or left axis deviation, which can be indicative of certain heart conditions.

💡Hypertrophy

Hypertrophy refers to the abnormal increase in the size of an organ or tissue, often due to the thickening of its walls. In the context of the heart, it usually refers to the thickening of the heart muscle walls, which can affect the heart's function. The script mentions hypertrophy as a cause of axis deviation, indicating that conditions like left ventricular hypertrophy or right ventricular hypertrophy can alter the heart's electrical activity and axis.

💡Ischemia

Ischemia is a medical condition where there is a lack of blood supply to a part of the body, usually due to a blocked artery. In the context of the heart, it refers to insufficient blood flow to the heart muscle, which can lead to angina or heart attack. The script mentions ischemia as one of the factors that can affect the heart's axis, indicating that the mean vector will deviate away from the infarct, which is the area affected by ischemia.

💡Pulmonary Hypertension

Pulmonary hypertension is a condition characterized by high blood pressure in the arteries of the lungs. This increased pressure can lead to right ventricular hypertrophy, as the right ventricle has to work harder to pump blood against the elevated pressure. The script mentions pulmonary hypertension as a condition that can cause right axis deviation on an EKG, which is indicative of enlarged right ventricle due to the increased workload.

💡QRS Complex

The QRS complex is a specific part of the EKG waveform that represents the electrical activity of the ventricles as they contract to pump blood out of the heart. The shape, duration, and amplitude of the QRS complex can provide valuable information about the heart's function and potential abnormalities. The script uses the QRS complex to determine the heart's electrical axis and identify any deviations from the normal pattern.

💡Left Ventricular Hypertrophy

Left ventricular hypertrophy (LVH) is a condition where the heart's main pumping chamber, the left ventricle, becomes thickened and enlarged. This can result from conditions such as high blood pressure, which causes the heart to work harder over time. In the context of the video, LVH is mentioned as a common cause of left axis deviation on an EKG, which can be a sign of long-standing hypertension.

💡Right Ventricular Hypertrophy

Right ventricular hypertrophy (RVH) is a condition where the right ventricle of the heart becomes thickened and enlarged, often due to increased workload such as pushing against elevated pulmonary artery pressure. This condition can lead to right axis deviation on an EKG, which is indicative of the changes in the heart's electrical activity due to the enlarged right ventricle.

Highlights

Exploring the 3D structure of the heart in 2D through EKG.

Understanding the importance of 12-lead EKG in capturing the heart's electrical rhythm from different angles.

The analogy of EKG to a chest x-ray, emphasizing the need to view from multiple perspectives to avoid missing crucial information.

Differentiating the portions of the heart that the 12 leads represent: anterior, posterior, and lateral.

Introducing the concept of 'axis' in relation to the heart's electrical flow and its representation on an EKG.

Describing the normal heart's electrical axis as leaning down and to the left, and how this is reflected in the EKG.

Explaining the quadrant method for determining the electrical axis of the heart using the QRS complex in lead I and AVF.

The significance of a positive QRS complex in lead I and a negative one in AVF indicating left axis deviation.

The association of left axis deviation with conditions like left ventricular hypertrophy and long-standing hypertension.

Discussing right axis deviation, its appearance on the EKG, and its link to right ventricular hypertrophy and pulmonary hypertension.

Beyond hypertrophy, other factors like ischemia can also influence the heart's electrical axis.

The necessity of determining the axis on every EKG to understand the heart's function and potential conditions.

Practical application of the quadrant method on actual 12-lead EKGs for axis determination.

The impact of various conditions on axis deviation and how it aids in diagnosing heart-related issues.

The comprehensive approach to analyzing EKGs, including rate, rhythm, and axis, for a holistic understanding of heart function.

Transcripts

two three yeah hey Katie what's going on

oh hey dr. camka just taking a look at

my patients EKGs trying to understand

what's going on in each of these leads I

don't even have 12 leads you know that's

a great question so we're looking at a

three-dimensional structure in 2d and so

the EKG represents a single snapshot of

the heart's electrical rhythm from 12

different angles oh so it's like a chest

x-ray when we look at the lateral and

the frontal plane if we look at one view

we might miss something you got it

exactly right and those 12 leads tell us

different portions of the heart the

anterior the posterior and so forth and

this actually leads us to our next

discussion so let's take a look at this

diagram here so we're taking a look at

the heart from 12 different angles right

and so we have two sets of leads we have

the precordial leads right here which

are the chest leads the purple ones that

are looking at the heart from the

horizontal axis and then we have the

green leads which are looking at the

heart from the frontal axis and we can

take this to take a look at certain

portions of the heart so we have two

three and Avia that are looking at the

inferior portion we have v1 through v4

that's looking at the anterior portion

of the heart and then on this side of me

we have v5 v6 and one an AVL they're

looking at the lateral portion of the

heart now let's take a look at how we

can use the leads to tell us about the

axis or the flow of electricity for the

heart so we hear a lot about axis what

is axis it simply represents the average

flow of electricity through the heart

your normal heart leans down and to the

left so it makes sense that the average

flow of electricity is also going to be

down into the left and we can take a

look at the EKG to kind of tell us which

direction the flow of electricity is

through the heart normal hearts are

going to be somewhere between 0 degrees

and minus 90 right axis deviation is

going to have the flow of the heart

between 105 to positive 180 degrees left

axis deviation is going to be minus 105

degrees to minus

180 degrees but it can get a little bit

complicated so my friend mark here is a

very simple method that can help explain

things yeah so I really like to use the

quadrant method I've heard about that I

like it yeah so the quadrant method we

mainly look at the QRS complex in two

leads please one in a Viet but what

about all the other leaves mark well

they're important too but we like to

keep it simple simple is always positive

so remember that lead one runs

horizontally and to the patient's left

and lead AVF runs vertically and towards

the patient's feet so if we have a

positive QRS complex and leads one and a

BF then we know our vector is somewhere

in between those two leads or normal

access that's pretty good mark let me

make it a little bit more challenging

for you so what if the lead is negative

in lead one and positive in AVF that

would mean that our axis is somewhere in

this quadrant we would call that right

axis deviation that's pretty good what

about if it's positive and lead one and

negative in AVF well though it means

that our axis is somewhere in this

quadrant and we would call that left

that axis deviation exactly right so now

that we have a better understanding of

how to determine axis let's practice on

a couple 12 lead EKG z' all right now

let's practice determining axis here we

have a complete 12 lead EKG which leads

do we want to look at when we determine

axis remember that when we talk about

axis we're talking about the frontal

plane so we want to look at the limb

leads so let's take a closer look at

those are which two leads were we

looking at when we were using the

quadrant method to determine access we

were looking at lead one and AVF we can

see in this EKG that lead one is

positive meaning we have at all our wave

predominance and AVF is negative meaning

there's a predominant s-wave positive

and one negative and AVF means left axis

deviation left axis deviation is

commonly seen in conditions like left

ventricular hypertrophy which we can see

in patients that have long

standing hypertension let's take a look

at another EKG now that you've got the

skills let's take a look at another EKG

this one has a different axis deviation

so just like Mark taught us we're going

to focus in on those limb leads so let's

zoom in on one and AVF so in one we have

mostly a downward deflection that

predominant s-wave and then in AVF

we see that it's mostly upright with a

tall R wave this is a right axis

deviation we see this most commonly and

someone with right ventricular

hypertrophy where the right ventricles

become bigger because it's pushing

against elevated pulmonary artery

pressure this is often an EKG that

you'll see in our pulmonary hypertension

patients you may have noticed that we've

mentioned hypertrophy twice now as a

cause of axis deviation but in fact

there are multiple things that can

affect our axis another important one is

ischemia the mean vector will deviate

away from the infarct right hypertrophy

ischemia and many other things can

affect our axis it's important to

determine the axis on every EKG that you

see so remember determine rate rhythm

axis on every EKG every time

you