When a doctor listens to your chest, they may say they can hear a murmur. Essentially, a murmur is an abnormal heart sound. This would be anything other than the normal ‘lub-dub’.
A murmur may sound like a ‘lub-swosh-dub’ or a ‘lub-dub-swosh’ or in some cases the ‘lub’ or ‘dub’ may sound particularly harsher than normal.
A common cause for a murmur is a narrowed/stuck valve, this is referred to as ‘stenosis’. The aortic valve is commonly effected. Therefore, a common cause for a murmur is ‘aortic stenosis’ (a narrowing of the aortic valve opening). This narrowing keeps the valve from opening fully, reducing blood flow to the body and making the heart work harder.
A normal aortic valve has three ‘cusps’ that open fully. The red shows the opening – where the blood flows out.
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Sometimes, you may be born with only 2 cusps. This would be called a bicuspid aortic valve. With only two cups, there is less space for the blood to flow out, meaning in some cases, you may be born with mild stenosis.
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A normal three leaflet valve may also develop aortic stenosis. This may be caused by excessive volume or pressure build up in the heart. This can cause high pressures to push against the valve causing micro-damage and small calcium deposits to form on the valve making it stiff.
You can see below the valve doesn’t open as wide and has white spots of calcium on the cusp tips. Red shows the small area the blood has to travel through.
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Below is a still image of a Doppler trace obtained from measuring a gradient through a severely stenotic aortic valve.
The green dotted line is where a normal trace would finish.
The red line is the cut off for ‘severe stenosis’ – where anything past this point has poor outcomes over the next few years if left un-managed.
The number circled in red (57.82mmHg) is essentially the additional pressure the heart must push against to get blood out – normally this number would be about 3.
In conclusion, while this chapter talked about aortic stenosis as a cause for heart murmurs, it is important to know that heart murmurs can occur from several other conditions such as Anaemia, Hyperthyroidism, a heart disease or a heart infection. Some heart murmurs may even be classed as ‘innocent’ heart murmurs, meaning they don’t need treatment and can sometimes go away on their own, although this is most common in childhood, with the murmur often disappearing by adulthood.
You can access bulk-billed echocardiograms at Cornwall Street Medical Centre in Woolloongabba, with a GP referral.
