Heart murmurs

A 57-year-old woman is listed for elective abdominal surgery. She has a history of

rheumatoid arthritis. On auscultation of her praecordium, a murmur is detected.

Regarding this patient, the following statements are true EXCEPT for which one?

a) If this murmur is related to a left-sided valve abnormality it will be heard louder

in expiration than inspiration

b) The most likely murmurs would be an apical pansystolic murmur radiating to

the axilla or a diastolic murmur heard best at the left sternal edge

c) If this murmur was secondary to aortic stenosis then a grade one sounding

murmur is of less significance than a grade five sounding murmur

d) If this murmur was secondary to mitral regurgitation, a quiet first heart sound

would be not altogether unsurprising

e) Atrial fibrillation would prompt suspicion of a mitral source of the murmur

Answer: C

Explanation

The usual heart sounds S1 and S2 are due to closure of the mitral and tricuspid valves

and the aortic and pulmonary valves respectively. Extra heart sounds S3 and S4 may be

normal (e.g. heard in athletes and young children) or abnormal, as in congestive

cardiac failure. Mitral regurgitation will therefore give a quiet S1. The audibility of

murmurs is graded from one to six – the higher the number, the louder the murmur. A

patient with aortic stenosis and a failing left ventricle will have a quieter murmur than

a similar degree of stenosis with a vigorous ventricle, so beware the quiet but significant

aortic stenosis! Rheumatoid arthritis is associated with both mitral and aortic

regurgitation, as is ankylosing spondylitis. Atrial fibrillation (AF) is most commonly

associated with mitral valve lesions, and the breathlessness associated with mitral

stenosis often worsens considerably with the onset of AF. In general, diastolic murmurs

are always pathological, mixed valve disease is common, and the valve lesion

you don’t want to miss as an anaesthetist is tight aortic stenosis. In general, murmurs

related to left-sided valve abnormalities will be heard louder in expiration than

inspiration, and vice versa for murmurs related to right-sided valve lesions. This is

because inspiration leads to increased venous return causing an increased blood

volume in the right side of the heart. This increased volume restricts the amount of

blood entering the left side of the heart, hence why left-sided murmurs are then quieter.

The opposite is true for expiration due to the reduced venous return that is seen.