Heart murmurs for beginners Part 2: Atrial septal defect, ventricular septal defect & PDAš„š„š„š„
Summary
TLDRIn 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
- šØāāļø Dr. Coleman introduces the episode by reviewing three types of heart murmurs related to specific cardiac conditions.
- š 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.
- š The mnemonic 'lub-wooshh-dubba' is provided to help remember the sound of the atrial septal defect murmur.
- š§ Atrial septal defects allow left-to-right shunting of blood, increasing the volume in the right atrium and ventricle, leading to the murmur.
- š The ejection systolic murmur of atrial septal defect is best heard at the left upper sternal border and may radiate to the back.
- š The second murmur is the pansystolic murmur found in ventricular septal defect, which occurs throughout systole and is represented by a plateau wave.
- š§¬ Ventricular septal defects are common congenital heart diseases, sometimes associated with genetic factors and conditions like Down syndrome.
- š« The loudness of the pansystolic murmur often masks the S1 and S2 heart sounds, making them difficult to hear.
- š 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.
- ā³ 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.
- š 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
šØāāļø 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.
š 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.
š 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.
Mindmap
Keywords
š”Heart Murmurs
š”Atrial Septal Defect (ASD)
š”Ejection Systolic Murmur
š”Ventricular Septal Defect (VSD)
š”Pansystolic Murmur
š”Patent Ductus Arteriosus (PDA)
š”Machinery Murmur
š”S2 Heart Sound
š”Left-to-Right Shunt
š”Eisenmenger's Syndrome
š”Ischemic 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 LearnĀ Medicine show. My name is Dr. Coleman,Ā Ā
and in this episode, we will review threeĀ more heart murmurs. These murmurs include:Ā
* The ejection systolic murmur with aĀ split S2 found in atrial septal defectĀ
* The pan-systolic murmur foundĀ in ventricular septal defectĀ
* The machinery murmur foundĀ in the patent ductus arteriosus
By now, you should be familiar with our diagramĀ that depicts one movement through the cardiacĀ Ā
cycle. You should also be familiar with theĀ concept that turbulent blood flow produces audibleĀ Ā
vibrations, which can be visually represented withĀ these sound wave patterns. If none of this soundsĀ Ā
familiar, please go back and watch the previousĀ video. I'll put a link at the top of the screen.Ā
Okay, so let's start by reviewing the murmurĀ of atrial septal defect. This presents with anĀ Ā
ejection systolic murmur and splitting of the S2Ā heart sound. This murmur occurs during systole andĀ Ā
is a crescendo-decrescendo murmur. To help commitĀ this murmur to memory, you can use the phraseĀ Ā
"lub-wooshh-dubba." Okay, so let's add in theĀ murmur now so you can appreciate how it sounds.
Okay, so let's take a moment to look at theĀ atrial septal defect and how the murmur occurs.Ā Ā
Here is our diagram of the heart. Let's removeĀ Ā
the pulmonary artery and the aorta toĀ get a closer look at what's going on.Ā
So looking at this diagram, you'll see that theĀ left atrium and the right atrium are separated byĀ Ā
a thin tissue called the interatrial septum.Ā It's here where atrial septal defects occur.Ā Ā
Atrial septal defects effectively allowĀ for an abnormal communication betweenĀ Ā
the left and the right atria. With this information in mind,Ā Ā
let's add in some blood flow and produce anĀ animation to see what happens with this defect.Ā
It's during diastole where we see most ofĀ the action with the atrial septal defect.Ā Ā
You can see here blood flowingĀ from the atria into the ventricles.Ā
But if we remove the aortaĀ and the pulmonary artery,Ā Ā
we can get a closer look at what is happening. Blood pressure in the left side of the heartĀ Ā
is naturally higher than that in the right sideĀ of the heart. This produces a pressure gradientĀ Ā
that allows blood to flow from theĀ left atrium into the right atrium.Ā Ā
This is known as a left-to-right shunt. The key point to take away here is thatĀ Ā
the left-to-right shunt allows increasedĀ volume of blood to enter the right atriumĀ Ā
and subsequently the right ventricle. So let's continue now by adding backĀ Ā
in the aorta and the pulmonary artery. As usual, the S1 heart sound is producedĀ Ā
by closure of the mitral and tricuspidĀ valves. This produces the sound "lub."Ā
Systole then occurs and during this time, theĀ ventricles contract and force blood throughĀ Ā
the pulmonary and the aortic valves. It is theĀ increased volume of blood in the right ventricleĀ Ā
being forced through the pulmonary valve thatĀ produces turbulent blood flow, resulting in ourĀ Ā
crescendo-decrescendo systolic murmur. As systole comes to an end,Ā Ā
the aortic valve closes as normal, producingĀ the first half of the S2 heart sound.Ā
The second half of the S2 heart sound is producedĀ by delayed closure of the pulmonary valve.Ā Ā
This delay occurs again becauseĀ of the increased volume of bloodĀ Ā
flowing out of the right ventricle. So let's watch this process now in an animation.Ā
Atrial septal defects effectively allow forĀ abnormal blood flow between the left and theĀ Ā
right atrium. They are usually congenital andĀ caused by failed closure of the foramen ovale.Ā
Atrial septal defects are more common in femalesĀ Ā
and also have increased frequency withĀ maternal alcohol use during pregnancy.Ā
In the clinical history, the presentationĀ may be asymptomatic. However, those thatĀ Ā
are symptomatic may have dyspnea and falteringĀ growth. In later life, other symptoms may occurĀ Ā
by the age of 25. The left-to-right shunt canĀ reverse due to increased pulmonary pressuresĀ Ā
and this produces a syndrome called Eisenmenger's. Atrial septal defect may also present as ischemicĀ Ā
stroke in later life. Here, small bloodĀ clots form in the venous system and theseĀ Ā
are able to pass from the right to theĀ left side of the heart through the defect.Ā Ā
Once in the arterial circulation, they can goĀ on to the brain to cause strokes. So any youngĀ Ā
person that has an unexplained stroke shouldĀ go on to have a check for atrial septal defect.Ā
The murmur produced in atrial septalĀ defect is an ejection systolic murmurĀ Ā
with splitting of the S2. It is heardĀ loudest in the left upper sternal borderĀ Ā
and radiates through to the back of the thorax.
And now let's turn our attention to ventricularĀ septal defects. This presents as a pansystolicĀ Ā
murmur, which essentially means that it occursĀ throughout the entire duration of systole.Ā Ā
This murmur can be visually represented with aĀ plateau wave. To commit this murmur to memory,Ā Ā
think about a bearing noise that occurs throughoutĀ the duration of systole. Let's listen to this now.
Let's take a moment to look at the anatomy ofĀ the ventricular septal defect. The left andĀ Ā
right ventricles are separated by a thin membraneĀ of tissue known as the interventricular septum.Ā Ā
It is here where ventricular septalĀ defects occur. This defect allows forĀ Ā
an abnormal communication betweenĀ the left and the right ventricle.
Let's use an animation now to understand how theĀ murmur occurs. Blood flows from the atria intoĀ Ā
the ventricles, and as usual, the tricuspid andĀ mitral valves close. However, due to increasedĀ Ā
pressure in the left ventricle compared toĀ the right ventricle, a left-to-right shuntĀ Ā
occurs across the ventricular septal defect. ThisĀ produces turbulent blood flow, which generatesĀ Ā
our pan-systolic murmur. The aortic and pulmonaryĀ valves close, and the cycle begins all over again.
It's worth noting that the S1 and S2Ā heart sounds are difficult to hearĀ Ā
in the context of a pan-systolic murmur,Ā often because the murmur itself is so loudĀ Ā
that it drowns them out. Let's watch theĀ animation now and listen to the murmur.
Let's pause for a moment to learnĀ more about ventricular septal defects.Ā Ā
They effectively form an abnormal communicationĀ between the left and right ventricles. VentricularĀ Ā
septal defects are a common type of congenitalĀ heart disease. It occurs due to abnormalĀ Ā
development of the ventricular septum early inĀ fetal development. Genetics also contribute toĀ Ā
the development of ventricular septal defects.Ā The risk is increased in those with a strongĀ Ā
family history and also in conditions such asĀ trisomy 21, otherwise known as Down syndrome.Ā Ā
With ischemic heart disease, particularly withĀ myocardial infarction, reduced blood supply to theĀ Ā
ventricular septum can cause it to break down andĀ rupture, producing a ventricular septal defect.
The clinical history may be asymptomatic, but mayĀ include dyspnea and failure to thrive. The murmurĀ Ā
of ventricular septal defect is a pan-systolicĀ murmur that is loudest at the left sternal edge.
Our final murmur in the series is thatĀ of patent ductus arteriosus. This isĀ Ā
described as a machinery murmur, and itĀ occurs throughout systole and diastole.Ā Ā
The murmur is represented visually with a plateauĀ wave that runs throughout systole and diastole.Ā Ā
To help commit this one to memory, think aboutĀ a continuous burrrring sound that runs the wholeĀ Ā
length of the cardiac cycle. We'll add inĀ the murmur now so you can appreciate this:
The ductus arteriosus is a fetal vascularĀ structure that allows blood to bypass theĀ Ā
lungs during fetal development. It usually closesĀ 48 hours after birth, but if it remains patent,Ā Ā
then it allows an abnormal communicationĀ between the aorta and the pulmonary artery.Ā Ā
The murmur is produced due to the high aorticĀ blood pressure and lower pulmonary pressures,Ā Ā
creating a gradient that allowsĀ for a left-to-right shunt,Ā Ā
where blood continuously flows from the aortaĀ into the pulmonary artery. A continuous stream ofĀ Ā
turbulent blood flow produces the machineryĀ murmur both through systole and diastole.
While the murmur is being produced, the mitralĀ and tricuspid valves close. The S1 heart soundĀ Ā
is not heard because the murmur is too loud andĀ drowns it out. This is then followed by bloodĀ Ā
being pumped into the pulmonary arteryĀ and the aorta. At the end of systole,Ā Ā
the pulmonary and the aortic valves close.Ā The S2 heart sound is not heard again becauseĀ Ā
the murmur is too loud and drowns it out. TheĀ murmur continues to rumble throughout diastole.
So, the patent ductus arteriosus is theĀ persistence of a fetal vascular structureĀ Ā
after birth. There is an increased risk ofĀ developing this condition with prematureĀ Ā
birth, with maternal rubella infection duringĀ pregnancy, and with female gender. The historyĀ Ā
may present with shortness of breath, recurrentĀ respiratory infections, or failure to thrive.
Patent ductus arteriosus produces aĀ machinery murmur, which is a low-pitchedĀ Ā
rumbling burrowing sound that is continuousĀ throughout systole and diastole. It is loudestĀ Ā
in the left infraclavicular area. OtherĀ signs you may see on clinical examinationĀ Ā
are a systolic thrill, bounding peripheralĀ pulse, and a widened pulse pressure.
And that brings us to the end of our heart murmursĀ module. Please take a look at the self-test thatĀ Ā
I'm posting, where you can test your abilityĀ to identify murmurs by answering some simpleĀ Ā
questions. Also, don't forget to head over to theĀ YouTube community channel where you'll be able toĀ Ā
vote on the topic for the next Learn MedicineĀ show. I really value your input because I wantĀ Ā
to be making videos that are useful for you. And with that said, don't forget to like andĀ Ā
subscribe and share with your friends. Thanks forĀ stopping by, and I'll see you in the next show!
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