Summary of Common Conditions Seen in OSCEs
Hints and Tips for the Exam
Identifying Valvular Lesions
Trying to learn all the murmurs and all the conditions associated with them is futile and only really necessary if you are a cardiologist. Trying to correctly differentiate whether murmurs are ejection systolic or pansystolic, end-diastolic rather than mid-diastolic, is also difficult and is not necessary for finals and perhaps even PACES.
The easiest and most logical way of diagnosing the correct valvular lesion from the murmur is by answering the following two questions:
Murmurs can frequently be heard throughout the chest, but the area where a murmur is loudest is usually where the murmur is – so a murmur heard loudest in the aortic area will probably be aortic regurgitation (AR) or aortic stenosis (AS), and a murmur heard loudest in the mitral area will probably be mitral regurgitation (MR) or mitral stenosis (MS). Exceptions to this include Gallavardin’s phenomenon, in which an AR murmur is heard loudest in the tricuspid area; however, from the perspective of passing an exam, you would not be penalised for missing that, and in any case it is extremely rare.
In other words, does the murmur correspond with the pulse (systolic) or not (diastolic)?
Murmurs will only be produced if the natural flow of the blood is opposed. In the case of valves through which the blood leaves the heart (such as the aortic valve), systolic murmurs will only be produced when the outflow of blood is hindered, which can only happen in AS (as opposed to AR, which would not hinder the outflow of blood).
In the case of valves where the blood flows into the heart in diastole, the natural flow of blood in diastole is against the aortic valve, as the purpose of the aortic valve is to stop blood flowing into the aorta during diastole. Hence blood hits the aortic valves and stops there when the cardiac muscles relax in diastole. This natural flow would be impaired by AR as the blood flows into the aorta when it should not, which is why a diastolic murmur in the aortic area can only be AR.
If this seems too complex, remember that diastolic murmurs are usually ‘ARMS’ (AR or MS), and the area where it is loudest is probably where the murmur is.
Right Versus Left
- LEFT-sided murmurs are louder in EXPIRATION.
- RIGHT-sided murmurs are louder in INSPIRATION.
This is because more blood flows into the intrathoracic cavity and lungs on inspiration, and hence more blood flows through the right-sided heart valves as these supply the lungs. The converse is true for left-sided murmurs.
It is vital to ask patients to hold their breath when using this test, but you must not ask them to do this for too long as this can cause the patient pain and you will fail the exam. Its often a good idea to hold your own breath at the same time so that you will know when it is getting too long to allow your patient to breath normally.
Timing the Murmur
Timing murmurs is something that both students and experienced doctors have difficulty with. Just remember to palpate the pulse when listening to the heart sound, and see if you hear the murmur at the same time as you feel the pulse.
- If the murmur is WITH the pulse, it is a SYSTOLIC murmur.
- If the murmur if NOT WITH the pulse, it is a DIASTOLIC murmur.
Use a central pulse such as the carotid or brachial to do this, otherwise it will not be accurate.
Diastolic Murmurs
A number of conditions can cause diastolic murmurs, but the most common ones are AR and MS – this can be easily memorised using the mnemonic ‘ARMS’.
Diastolic murmurs are very difficult to elicit for even the most experienced doctors, and if you can hear a murmur easily, it is most likely to be systolic. However, if you do manage to identify a diastolic murmur, it is handy to remember that MS murmurs are much quieter than AR murmurs, and if you can auscultate a diastolic murmur throughout the chest, it is much more likely to be AR than MS.
Valve Replacements
If you see a midline sternotomy scar, you should immediately bring your ear close to the patient’s chest and listen carefully for the clicking noise that is indicative of the closing of a metallic valve replacement – this can easily be heard without a stethoscope.
Also remember that you should not hear a murmur with a replaced valve unless it is leaking.
Identifying Which Valve Has Been Replaced
Remember that the pulse correlates with the first heart sound, which is the mitral valve closing. (The second heart sound is the aortic valve closing.)
- If the loudest sound of the valve closing correlates with the pulse, it is the first heart sound, indicating that the mitral valve has been replaced.
- If the loudest sound of the valve does not correspond with the pulse, it is the second heart sound, indicating that the aortic valve has been replaced.
- The location of the loudest sounds may also be helpful. Bioprosthetic valves sound the same as normal heart valves, so it would be unfair for examiners to expect you to identify them.
Apex Beat
The apex beat is palpable in the 5th intercostal space, and is displaced to the apex in MR. Various characters of the apex beat have been described, such as ‘heaving’ and ‘thrusting’; differentiating between them is extremely difficult and probably beyond the scope of a 10-minute OSCE. Other than this, it is more likely to cause confusion than add anything substantive.
The best course of action is to describe where the apex beat it, and whether it is palpable or not. An impalpable apex beat is often caused by obesity, hyperinflation of the lungs, dextrocardia or poor technique.
Scars
Figures 1.1–1.5 show scars and other signs that you will need to note on your examination of the patient.
Figure 1.1 Graft scar from leg vein removal in coronary artery bypass grafting
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