Heart murmurs for beginners Part 2: Atrial septal defect, ventricular septal defect & PDA🔥🔥🔥🔥

Summary

In this episode of Learn Medicine, Dr. Coleman reviews three types of heart murmurs: ejection systolic murmur in atrial septal defect, pan-systolic murmur in ventricular septal defect, and machinery murmur in patent ductus arteriosus. He explains the cardiac cycle, how turbulent blood flow creates audible murmurs, and the specific characteristics of each murmur. The video also covers the causes, symptoms, and clinical implications of these defects, helping viewers to identify and understand heart murmurs effectively.

Takeaways

• 👨‍⚕️ Dr. Coleman introduces the episode by reviewing three types of heart murmurs related to specific cardiac conditions.
• 🔍 The first murmur discussed is the ejection systolic murmur with a split S2, associated with atrial septal defect, characterized by turbulent blood flow during systole.
• 📊 The mnemonic 'lub-wooshh-dubba' is provided to help remember the sound of the atrial septal defect murmur.
• 💧 Atrial septal defects allow left-to-right shunting of blood, increasing the volume in the right atrium and ventricle, leading to the murmur.
• 👂 The ejection systolic murmur of atrial septal defect is best heard at the left upper sternal border and may radiate to the back.
• 🔊 The second murmur is the pansystolic murmur found in ventricular septal defect, which occurs throughout systole and is represented by a plateau wave.
• 🧬 Ventricular septal defects are common congenital heart diseases, sometimes associated with genetic factors and conditions like Down syndrome.
• 🚫 The loudness of the pansystolic murmur often masks the S1 and S2 heart sounds, making them difficult to hear.
• 🌀 The final murmur is the machinery murmur in patent ductus arteriosus, a continuous murmur throughout systole and diastole due to abnormal blood flow between the aorta and pulmonary artery.
• ⏳ Patent ductus arteriosus is a fetal structure that may fail to close after birth, leading to a continuous murmur, and is associated with prematurity and maternal infections.
• 📝 The machinery murmur of patent ductus arteriosus is loudest in the left infraclavicular area and may present with a systolic thrill and bounding pulses.

Q & A

What are the three types of heart murmurs discussed in the video?

The three types of heart murmurs discussed are the ejection systolic murmur with a split S2 found in atrial septal defect, the pan-systolic murmur found in ventricular septal defect, and the machinery murmur found in patent ductus arteriosus.

What is the characteristic sound of an ejection systolic murmur in atrial septal defect?

The ejection systolic murmur in atrial septal defect is a crescendo-decrescendo murmur, which can be remembered by the phrase 'lub-wooshh-dubba'.

How does the interatrial septum relate to atrial septal defects?

The interatrial septum is a thin tissue that separates the left and right atria. Atrial septal defects occur in this tissue, allowing abnormal communication between the left and right atria.

What is the significance of the left-to-right shunt in atrial septal defects?

The left-to-right shunt in atrial septal defects allows an increased volume of blood to enter the right atrium and subsequently the right ventricle, leading to turbulent blood flow and the characteristic murmur.

What are the typical symptoms of atrial septal defects in clinical history?

Clinical history of atrial septal defects may include asymptomatic cases, dyspnea, faltering growth, and in later life, symptoms may occur by the age of 25 due to increased pulmonary pressures.

What is the visual representation of a pan-systolic murmur found in ventricular septal defects?

A pan-systolic murmur is visually represented with a plateau wave, indicating that it occurs throughout the entire duration of systole.

How does the interventricular septum relate to ventricular septal defects?

The interventricular septum is a thin membrane of tissue that separates the left and right ventricles. Ventricular septal defects occur in this septum, allowing abnormal communication between the ventricles.

What is the typical location to hear the murmur of ventricular septal defects?

The murmur of ventricular septal defects is a pan-systolic murmur that is loudest at the left sternal edge.

What is the fetal structure that, if not closed after birth, can cause a patent ductus arteriosus?

The ductus arteriosus is a fetal vascular structure that allows blood to bypass the lungs during fetal development. If it remains open after birth, it can cause a patent ductus arteriosus.

What is the characteristic sound of a patent ductus arteriosus?

A patent ductus arteriosus produces a machinery murmur, which is a low-pitched, continuous burrrring sound throughout systole and diastole.

What are some risk factors for developing a patent ductus arteriosus?

Risk factors for developing a patent ductus arteriosus include prematurity, maternal rubella infection during pregnancy, and female gender.

Outlines

00:00

👨‍⚕️ Atrial Septal Defect Murmur Overview

In this section, Dr. Coleman introduces the topic of heart murmurs, specifically focusing on three types: the ejection systolic murmur with a split S2 in atrial septal defect, the pan-systolic murmur in ventricular septal defect, and the machinery murmur in patent ductus arteriosus. He explains the concept of turbulent blood flow causing audible vibrations and the importance of understanding cardiac cycle diagrams. The murmur of atrial septal defect is characterized by an ejection systolic murmur and a split S2 heart sound, occurring during systole with a crescendo-decrescendo pattern. The animation provided illustrates the abnormal blood flow between the left and right atria due to the atrial septal defect, which is typically congenital and can lead to various symptoms, including dyspnea, faltering growth, and a potential reversal of the left-to-right shunt known as Eisenmenger's syndrome.

05:06

🔍 Ventricular Septal Defect and Its Murmur

This paragraph delves into the anatomy and murmur associated with ventricular septal defects. The interventricular septum separates the left and right ventricles, and a defect in this tissue allows for abnormal communication between them. The murmur is pansystolic, occurring throughout systole, and is represented by a plateau wave. The animation demonstrates how the increased pressure in the left ventricle leads to a left-to-right shunt across the defect, causing turbulent blood flow and the characteristic murmur. Ventricular septal defects are common congenital heart diseases, potentially linked to genetic factors and conditions like Down syndrome. Clinical presentations may vary, with some individuals being asymptomatic, while others may experience dyspnea and failure to thrive.

10:09

🚑 Patent Ductus Arteriosus and Its Continuous Murmur

The final paragraph discusses patent ductus arteriosus, a condition where a fetal blood vessel remains open after birth, allowing abnormal communication between the aorta and pulmonary artery. This results in a machinery murmur heard throughout both systole and diastole due to the continuous turbulent blood flow from the aorta to the pulmonary artery. The murmur is best heard in the left infraclavicular area and may be accompanied by a systolic thrill and bounding peripheral pulse. Risk factors for patent ductus arteriosus include prematurity, maternal rubella infection, and female gender. Clinical signs may include shortness of breath, recurrent respiratory infections, and failure to thrive. The video concludes with an invitation for viewers to participate in a self-test and engage with the Learn Medicine community to influence future video topics.

Keywords

💡Heart Murmurs

Heart murmurs are abnormal sounds heard during the heartbeat cycle, caused by turbulent blood flow through the heart. In the video, three specific heart murmurs are discussed, each associated with different cardiac conditions. The murmurs are central to the video's theme of understanding cardiac abnormalities through auscultation.

💡Atrial Septal Defect (ASD)

An atrial septal defect is a congenital heart condition where there is an abnormal opening in the interatrial septum, allowing blood to flow between the left and right atria. The video explains that ASD presents with an ejection systolic murmur and splitting of the S2 heart sound, illustrating the concept through a detailed animation and clinical implications.

💡Ejection Systolic Murmur

An ejection systolic murmur is a heart sound that occurs during systole and increases then decreases in intensity, described as a crescendo-decrescendo pattern. The video uses the phrase 'lub-wooshh-dubba' to help viewers remember this type of murmur, specifically in the context of an atrial septal defect.

💡Ventricular Septal Defect (VSD)

A ventricular septal defect is another congenital heart condition where there is an abnormal communication between the left and right ventricles. The video describes the murmur associated with VSD as a pansystolic murmur, occurring throughout systole, and uses a bearing noise analogy to help viewers understand the sound.

💡Pansystolic Murmur

A pansystolic murmur is a continuous murmur heard throughout the entire systolic phase of the cardiac cycle. The video explains that this type of murmur is indicative of a ventricular septal defect and is so loud that it often drowns out the S1 and S2 heart sounds.

💡Patent Ductus Arteriosus (PDA)

Patent ductus arteriosus refers to a condition where the fetal blood vessel that bypasses the lungs, the ductus arteriosus, fails to close after birth. The video describes the murmur associated with PDA as a machinery murmur, heard throughout both systole and diastole, due to the continuous turbulent blood flow between the aorta and pulmonary artery.

💡Machinery Murmur

A machinery murmur is a continuous, low-pitched sound heard in cases of patent ductus arteriosus. The video uses the term 'burrrring sound' to describe this murmur, which is indicative of the unobstructed blood flow between the aorta and pulmonary artery throughout the cardiac cycle.

💡S2 Heart Sound

The S2 heart sound, also known as the second heart sound, is produced by the closure of the aortic and pulmonary valves. In the context of the video, the splitting of the S2 sound is a key feature of the murmur in atrial septal defects, and its delayed closure is mentioned in relation to the increased blood volume in the right ventricle.

💡Left-to-Right Shunt

A left-to-right shunt describes the abnormal flow of blood from the left side of the heart to the right side, typically due to a defect such as an atrial or ventricular septal defect. The video explains how this shunt leads to increased blood volume in the right atrium and ventricle, resulting in characteristic murmurs.

💡Eisenmenger's Syndrome

Eisenmenger's syndrome is a condition that can occur in individuals with a left-to-right shunt due to a septal defect, where the shunt reverses due to increased pulmonary pressure. The video mentions this syndrome as a potential long-term complication of atrial septal defects, leading to symptoms such as dyspnea and reduced exercise capacity.

💡Ischemic Stroke

An ischemic stroke occurs when blood supply to a part of the brain is interrupted or reduced, typically by a blood clot. The video explains the connection between atrial septal defects and ischemic strokes, where small blood clots can pass from the right side of the heart to the left and then to the brain, causing a stroke.

Highlights

Introduction to the Learn Medicine show with Dr. Coleman reviewing three types of heart murmurs.

Explanation of the ejection systolic murmur with a split S2 found in atrial septal defect.

Description of the pan-systolic murmur found in ventricular septal defect.

Introduction of the machinery murmur found in patent ductus arteriosus.

Use of a diagram to depict the cardiac cycle and the concept of turbulent blood flow.

Memory aid 'lub-wooshh-dubba' for the murmur of atrial septal defect.

Animation of blood flow in atrial septal defect and the resulting left-to-right shunt.

Discussion on the increased volume of blood in the right ventricle causing a murmur.

Clinical history and symptoms associated with atrial septal defect.

Risk factors for atrial septal defects, including maternal alcohol use and gender.

Importance of checking for atrial septal defect in young people with unexplained strokes.

Characteristics of the pansystolic murmur in ventricular septal defects.

Anatomy of the ventricular septal defect and its impact on blood flow.

Clinical presentation of ventricular septal defects and associated conditions.

Explanation of patent ductus arteriosus as a persistent fetal vascular structure.

Description of the machinery murmur in patent ductus arteriosus and its causes.

Risk factors for patent ductus arteriosus, including prematurity and maternal infections.

Clinical signs of patent ductus arteriosus, such as systolic thrill and bounding pulses.

Invitation to participate in a self-test and vote on topics for future Learn Medicine shows.

Transcripts

[Music]

Hello and welcome back to the Learn  Medicine show. My name is Dr. Coleman,  

and in this episode, we will review three  more heart murmurs. These murmurs include: 

* The ejection systolic murmur with a  split S2 found in atrial septal defect 

* The pan-systolic murmur found  in ventricular septal defect 

* The machinery murmur found  in the patent ductus arteriosus

By now, you should be familiar with our diagram  that depicts one movement through the cardiac  

cycle. You should also be familiar with the  concept that turbulent blood flow produces audible  

vibrations, which can be visually represented with  these sound wave patterns. If none of this sounds  

familiar, please go back and watch the previous  video. I'll put a link at the top of the screen. 

Okay, so let's start by reviewing the murmur  of atrial septal defect. This presents with an  

ejection systolic murmur and splitting of the S2  heart sound. This murmur occurs during systole and  

is a crescendo-decrescendo murmur. To help commit  this murmur to memory, you can use the phrase  

"lub-wooshh-dubba." Okay, so let's add in the  murmur now so you can appreciate how it sounds.

Okay, so let's take a moment to look at the  atrial septal defect and how the murmur occurs.  

Here is our diagram of the heart. Let's remove  

the pulmonary artery and the aorta to  get a closer look at what's going on. 

So looking at this diagram, you'll see that the  left atrium and the right atrium are separated by  

a thin tissue called the interatrial septum.  It's here where atrial septal defects occur.  

Atrial septal defects effectively allow  for an abnormal communication between  

the left and the right atria. With this information in mind,  

let's add in some blood flow and produce an  animation to see what happens with this defect. 

It's during diastole where we see most of  the action with the atrial septal defect.  

You can see here blood flowing  from the atria into the ventricles. 

But if we remove the aorta  and the pulmonary artery,  

we can get a closer look at what is happening. Blood pressure in the left side of the heart  

is naturally higher than that in the right side  of the heart. This produces a pressure gradient  

that allows blood to flow from the  left atrium into the right atrium.  

This is known as a left-to-right shunt. The key point to take away here is that  

the left-to-right shunt allows increased  volume of blood to enter the right atrium  

and subsequently the right ventricle. So let's continue now by adding back  

in the aorta and the pulmonary artery. As usual, the S1 heart sound is produced  

by closure of the mitral and tricuspid  valves. This produces the sound "lub." 

Systole then occurs and during this time, the  ventricles contract and force blood through  

the pulmonary and the aortic valves. It is the  increased volume of blood in the right ventricle  

being forced through the pulmonary valve that  produces turbulent blood flow, resulting in our  

crescendo-decrescendo systolic murmur. As systole comes to an end,  

the aortic valve closes as normal, producing  the first half of the S2 heart sound. 

The second half of the S2 heart sound is produced  by delayed closure of the pulmonary valve.  

This delay occurs again because  of the increased volume of blood  

flowing out of the right ventricle. So let's watch this process now in an animation. 

Atrial septal defects effectively allow for  abnormal blood flow between the left and the  

right atrium. They are usually congenital and  caused by failed closure of the foramen ovale. 

Atrial septal defects are more common in females  

and also have increased frequency with  maternal alcohol use during pregnancy. 

In the clinical history, the presentation  may be asymptomatic. However, those that  

are symptomatic may have dyspnea and faltering  growth. In later life, other symptoms may occur  

by the age of 25. The left-to-right shunt can  reverse due to increased pulmonary pressures  

and this produces a syndrome called Eisenmenger's. Atrial septal defect may also present as ischemic  

stroke in later life. Here, small blood  clots form in the venous system and these  

are able to pass from the right to the  left side of the heart through the defect.  

Once in the arterial circulation, they can go  on to the brain to cause strokes. So any young  

person that has an unexplained stroke should  go on to have a check for atrial septal defect. 

The murmur produced in atrial septal  defect is an ejection systolic murmur  

with splitting of the S2. It is heard  loudest in the left upper sternal border  

and radiates through to the back of the thorax.

And now let's turn our attention to ventricular  septal defects. This presents as a pansystolic  

murmur, which essentially means that it occurs  throughout the entire duration of systole.  

This murmur can be visually represented with a  plateau wave. To commit this murmur to memory,  

think about a bearing noise that occurs throughout  the duration of systole. Let's listen to this now.

Let's take a moment to look at the anatomy of  the ventricular septal defect. The left and  

right ventricles are separated by a thin membrane  of tissue known as the interventricular septum.  

It is here where ventricular septal  defects occur. This defect allows for  

an abnormal communication between  the left and the right ventricle.

Let's use an animation now to understand how the  murmur occurs. Blood flows from the atria into  

the ventricles, and as usual, the tricuspid and  mitral valves close. However, due to increased  

pressure in the left ventricle compared to  the right ventricle, a left-to-right shunt  

occurs across the ventricular septal defect. This  produces turbulent blood flow, which generates  

our pan-systolic murmur. The aortic and pulmonary  valves close, and the cycle begins all over again.

It's worth noting that the S1 and S2  heart sounds are difficult to hear  

in the context of a pan-systolic murmur,  often because the murmur itself is so loud  

that it drowns them out. Let's watch the  animation now and listen to the murmur.

Let's pause for a moment to learn  more about ventricular septal defects.  

They effectively form an abnormal communication  between the left and right ventricles. Ventricular  

septal defects are a common type of congenital  heart disease. It occurs due to abnormal  

development of the ventricular septum early in  fetal development. Genetics also contribute to  

the development of ventricular septal defects.  The risk is increased in those with a strong  

family history and also in conditions such as  trisomy 21, otherwise known as Down syndrome.  

With ischemic heart disease, particularly with  myocardial infarction, reduced blood supply to the  

ventricular septum can cause it to break down and  rupture, producing a ventricular septal defect.

The clinical history may be asymptomatic, but may  include dyspnea and failure to thrive. The murmur  

of ventricular septal defect is a pan-systolic  murmur that is loudest at the left sternal edge.

Our final murmur in the series is that  of patent ductus arteriosus. This is  

described as a machinery murmur, and it  occurs throughout systole and diastole.  

The murmur is represented visually with a plateau  wave that runs throughout systole and diastole.  

To help commit this one to memory, think about  a continuous burrrring sound that runs the whole  

length of the cardiac cycle. We'll add in  the murmur now so you can appreciate this:

The ductus arteriosus is a fetal vascular  structure that allows blood to bypass the  

lungs during fetal development. It usually closes  48 hours after birth, but if it remains patent,  

then it allows an abnormal communication  between the aorta and the pulmonary artery.  

The murmur is produced due to the high aortic  blood pressure and lower pulmonary pressures,  

creating a gradient that allows  for a left-to-right shunt,  

where blood continuously flows from the aorta  into the pulmonary artery. A continuous stream of  

turbulent blood flow produces the machinery  murmur both through systole and diastole.

While the murmur is being produced, the mitral  and tricuspid valves close. The S1 heart sound  

is not heard because the murmur is too loud and  drowns it out. This is then followed by blood  

being pumped into the pulmonary artery  and the aorta. At the end of systole,  

the pulmonary and the aortic valves close.  The S2 heart sound is not heard again because  

the murmur is too loud and drowns it out. The  murmur continues to rumble throughout diastole.

So, the patent ductus arteriosus is the  persistence of a fetal vascular structure  

after birth. There is an increased risk of  developing this condition with premature  

birth, with maternal rubella infection during  pregnancy, and with female gender. The history  

may present with shortness of breath, recurrent  respiratory infections, or failure to thrive.

Patent ductus arteriosus produces a  machinery murmur, which is a low-pitched  

rumbling burrowing sound that is continuous  throughout systole and diastole. It is loudest  

in the left infraclavicular area. Other  signs you may see on clinical examination  

are a systolic thrill, bounding peripheral  pulse, and a widened pulse pressure.

And that brings us to the end of our heart murmurs  module. Please take a look at the self-test that  

I'm posting, where you can test your ability  to identify murmurs by answering some simple  

questions. Also, don't forget to head over to the  YouTube community channel where you'll be able to  

vote on the topic for the next Learn Medicine  show. I really value your input because I want  

to be making videos that are useful for you. And with that said, don't forget to like and  

subscribe and share with your friends. Thanks for  stopping by, and I'll see you in the next show!