Hello, and welcome back to the Learn Medicine Show. My name is Dr Coleman, and in this episode, we are covering four heart murmurs that typically come up in exams. We're going to start by covering the basic heart sounds, and then we'll add in the murmurs so that you can get to know them.
Let's get into this. Heart sounds can be graphically represented in medical notes as S1, S2, and S1 again, and this represents one movement through the cardiac cycle. The gap between S1 and S2 is known as systole, and the gap between S2 and S1 is known as diastole.
Before we start adding in murmurs, I want you to be familiar with the normal heart sound. So let's briefly cover these. The S1 heart sound usually sounds like the word "LUB," and the S2 "DUB.
" Let's add in the heart sounds briefly so you can familiarise yourself with this. Now let's turn our attention towards heart murmurs. Murmurs occur when there is a disruption of normal laminar blood flow.
The disruption can be caused by physiological or pathophysiological conditions, and this leads to turbulent flow, which produces audible vibrations. These audible vibrations vary in their volume based on the turbulent flow produced. These pictorial representations of sound waves are what we use to document murmurs in our heart sounds diagram.
So let's get down to business now and start by looking at systolic murmurs. Our first systolic murmur is aortic stenosis. Aortic stenosis typically produces what's known as an ejection systolic murmur.
This is a murmur that occurs during systole and is represented by a crescendo-decrescendo sound wave. One strategy for recognising and remembering this murmur is using the schema LUB-WOOSH-DUB. We'll now add in the murmur and heart sounds so you can fully appreciate this.
This murmur is produced by the abnormal narrowing of the aortic valve. Let's take a closer look now at how this occurs. Blood flows from the atria into the ventricles, and the first heart sound is produced by the closure of the tricuspid and mitral valves.
Systole then occurs. The ventricles contract, forcing blood through the pulmonary and aortic valves. Narrowing of the aortic valve creates turbulent blood flow through the aortic valve.
It is this turbulent blood flow that produces our crescendo-decrescendo murmur. Finally, the S2 heart sound is produced by the closure of the pulmonary and aortic valves. Let's now add in the murmur so that you can appreciate this in real-time.
"Now that we've heard the murmur, let's take a closer look at aortic stenosis. Aortic stenosis is caused by abnormal narrowing of the aortic valve, and the aetiology includes age-related calcification, congenital bicuspid valve, and rheumatic fever. The clinical history will typically include angina, syncope, and dyspnea.
The murmur of aortic stenosis is characterised as an ejection systolic murmur. The murmur is louder in expiration and heard best in the aortic region and in the apex of the heart. The murmur radiates in the direction of blood flow towards the carotid arteries.
On clinical examination, you may also find a slow-rising pulse and low blood pressure. Let's turn our attention to mitral regurgitation. Here we have another systolic murmur, but this time it's described as a pan-systolic murmur.
As you may have already gathered from its name, this occurs throughout the entire duration of systole. This murmur is represented visually with a plateau waveform, meaning that the volume of the murmur remains consistent throughout its duration. The murmur is so loud that it drowns out S1 and S2, and instead, a burbling sound is heard.
Let's pause and take a quick listen to this now. This pan-systolic murmur is caused by abnormal closure of the mitral valve. Let's take a closer look to get a better understanding of this.
So, blood flows from the atria through the mitral and tricuspid valves into the ventricles, and at this point, the mitral and tricuspid valves would normally close to produce our S1 heart sound. But instead of this, the mitral valve prolapses into the left atrium, and this causes turbulent blood flow, which generates a murmur that drowns out the S1 and the S2 heart sound. Let's add in the murmur so that you can appreciate this in real-time.
Mitral regurgitation is caused by abnormal closure of the mitral valve, and this can be due to a number of reasons, including mitral prolapse, ischemic heart disease, rheumatic fever, and infective endocarditis. The clinical history will usually include dyspnea and fatigue. " Mitral regurgitation produces a pan-systolic murmur that is loudest at the apex of the heart and radiates into the left axilla.
Other signs you may see on examination include a displaced apex beat and a parasternal heave. In severe cases, you may see peripheral oedema. Let's now turn our attention towards diastolic murmurs, and we're going to cover two.
The first one is aortic regurgitation. This murmur is heard during diastole and is considered an early diastolic murmur. It is represented pictorially with a decrescendo sound wave.
The words "lub-tar" can be used to describe how this murmur sounds. Let's listen to this in real time so you can appreciate this better. Aortic regurgitation is caused by abnormal closure of the aortic valve.
Let's take a closer look at this using animation. The first heart sound is produced by the closure of the tricuspid and mitral valves. Systole occurs when the ventricles contract, forcing blood through the pulmonary and aortic valves.
Incomplete closure of the aortic valve allows blood to regurgitate back into the ventricle. This turbulent blood flow causes our diastolic murmur. Let's now add in the heart sounds and watch this occur in real time.
Aortic regurgitation is caused by abnormal closure of the aortic valve. This may occur due to rheumatic fever but is also seen in connective tissue diseases such as Marfan's syndrome and rheumatological conditions like rheumatoid arthritis and lupus. Another possible cause is infective endocarditis.
The clinical history will usually present with the smear, and the patient may present with symptoms of angina. Aortic regurgitation produces an early diastolic murmur that is her loudest at the left sternal edge and radiates towards the apex of the heart. Other signs you might see on clinical examination include a collapsing pulse, a wide pulse pressure, and a displaced apex beat.
Now let's turn our attention to our final murmur, the murmur of mitral stenosis. Mitral stenosis produces a diastolic murmur that is described as a mid-diastolic murmur. It has an opening snap and a decrescendo sound wave, meaning it starts loud and then becomes quieter.
To help recognise this mid-diastolic murmur, the terms "lub-di-der" are often used. Let's pause for a moment to listen to this in real-time so that you can appreciate this better. [Music] Mitral stenosis, as its name suggests, is caused by abnormal narrowing of the mitral valve.
Let's now take a look at an animation to see how this narrowing causes the murmur. The S1 heart sound is produced by the closure of the tricuspid and mitral valves. Systole then occurs, where ventricular contraction pushes blood through the pulmonary and aortic valves.
Closure of the pulmonary and aortic valves produces the S2 heart sound. But milliseconds after this, accumulated blood in the left atrium increases the left atrial pressure to a point where the stiffened mitral valve is forced open, and this produces an opening snap. Almost immediately after S2, blood rushes through the narrowed mitral valve, producing turbulent flow, and this is audible vibrations from these that produce our mid-diastolic decrescendo murmur.
Let's take a moment now to add in the murmur so you can appreciate it in real-time. [Music] Mitral stenosis is an abnormal narrowing of the mitral valve. The most common cause of this is rheumatic fever, and less common causes include congenital heart disease and systemic diseases such as lupus.
The clinical history typically presents with dyspnea and palpitations if atrial fibrillation is present. Mitral stenosis produces a mid-diastolic murmur with an opening snap that is heard loudest at the apex and radiates to the axilla. Other signs that you may see on clinical examination include malar flush and a tapping apex beat.
And that brings us to the end of the tutorial. So, if you enjoyed this, please like and subscribe, share with your friends, and let me know what you think in the comments below. Thanks for dropping by.
I'll see you again soon.
