A Simplified Approach to Cardiac Murmurs For Medical Students

When I was a medical student, I devised a simplistic approach to cardiac murmurs. Later on when I was sitting for the MRCP exam, I took the same system and improved on it.

After teaching medical students internal medicine for a number of years, I realised that many can probably benefit from a more organised approach when dealing with the subject of cardiac murmurs. The same can probably be said for:

• The neurological exam (some students like to refer to this as the CNS exam, which is in reality, inaccurate, because the nervous system exam can generally be divided into the cranial nerves exam and the peripheral nervous system exam).
• ECG interpretation
• Chest X-ray interpretation

Are cardiac murmurs common in the exams? 

Yes, they are. 

They can come up as a short case, or can be part of the medical long case exams. Most patients are well and stable, making them very suitable examination candidates.

I can still remember the mature lady who was one of my short cases for the final year medical exams. I was the last candidate on that day and the lady was probably hungry or tired, every time I asked her to take a deep breath in, or lean to one side, she would comply, but she also frowned and sighed very loudly with each step. I was mildly put off but just carried on regardless.

And for the MRCP short cases? Since I had to take the exam more than once, there was almost a murmur for every attempt.

I can distinctly remember the young man with aortic regurgitation, the continuous machinery murmur that was practically heard everywhere...and others I can no longer recall without effort.

In the long case, the presence of a cardiac murmur should not come as a surprise. What I mean by that is, the history and other part of the examination would have hinted that there would be some abnormality before you place the stethoscope on the heart.

Here are some simple tips to handling heart murmurs in the internal medicine short cases.

• Always, always, always, palpate the pulse as you auscultate the four cardiac areas. Make it a habit even when there is no murmur, so that you know which is the first and which is the second heart sound.

Its interesting that students can listen to all four areas, then stand back and say "I heard a murmur but I'm not sure what murmur it is". 

I remember doing that when I was a student.

So my first question is always "Did you hear the first and second heart sound?"

"Yes, I did....

The first and second heart sound was heard", the student presents in a quivering voice.

"And how did the murmur relate to the first and second heart sound?" I try to make the student realise what they had not done.

Sometimes they realise and ask permission to auscultate again, this time while palpating the carotid/brachial/radial pulse. 

Other times, they don't realise, so the lecturer has to spell it out. 

"Why am I asking?

Did the murmur coincide with the first heart sound?"

Some students find it hard to think under pressure. Sometimes I turn to their colleagues who then tell them right answer, not that they don't know, I'm sure they know, but they are just a bit nervous.

"You didn't palpate the carotid pulse" the other says.

Well, it doesn't have to be the carotid, any pulse is fine. The carotids might be easier to palpate for some due to its location.

The basic principles are:

• if the murmur coincides with the first heart sound, it is a systolic murmur.

• If it doesn't coincide with the first heart sound, it is a diastolic murmur.

Other possibilities are continuous murmurs, which occur through out the cardiac cycle, and these can be due certain lesions or a combination of lesions. We'll come back to this later.

Sometimes, even if you have done your best and listened while palpating the pulse, and you are still not sure whether it is a systolic or diastolic murmur, well, in the exams, you can guess and you have a fifty-fifty chance of getting it right (or wrong).

If you had to guess, then go for systolic murmurs as they tend to be:

• more common
• easier to hear compared to diastolic murmurs which tend to be low-pitched

Of course when guessing, there is a chance one might be wrong. Rather have no answer, sometimes it is better to guess.

• For the sake of simplification, I memorised, as a medical student, four of the more common murmurs:

• Mitral regurgitation
• Aortic stenosis
• Mitral stenosis
• Aortic regurgitation

This is what I memorised, not only memorised, I also made sure I could say it fluently without referring to my notes, and understood what I was describing (I incorporated the findings into my clinical examination).

Mitral regurgitation is a pansystolic murmur that is heard loudest at the apex, heard through out the praecordium, radiates to the axilla, and is accentuated by expiration.

Aortic stenosis is an ejection systolic murmur heard loudest at the aortic area, radiates to the carotids, and in accentuated by the patient leaning forward in expiration.

Mitral stenosis is a mid-diastolic rumbling murmur heard at the apex and accentuated with the patient leaning on the left side in expiration.

Aortic regurgitation is an early-diastolic murmur heard best at the left sternal edge/tricuspid area, accentuated by the patient leaning forward in expiration.

While in reality, there are many other murmurs not included in the above simplified list, and it does not take into account combined lesions, but it serves as a good reference that should you be completely lost and not know what is going on during the examination of the praecordium, before you lift your stethoscope and turn to present your findings, its a good idea to just choose one or more of the above to present as your findings.

In reality of course, no matter how weird or complex or straightforward the murmur is, we would usually proceed to have an echo-cardiogram to assist in the management and interpretation.

Hope this helps.