Third heart sound, AKA gallop rhythm, can be perfectly normal in children and young adults.
It is due to passive filling of the ventricles when the atrioventricular valves open.
In the over 40s it is pathological and may indicate:
- mitral regurgitation
- constrictive pericarditis
S1 S2 S3
The sound of the 3rd heart sound may be remembered as 'Kentucky' or 'SLOSH-ing in'
Fourth heart sound
A 4th heart sound is caused by atrial contraction against stiff ventricles.
It occurs in:
- aortic stenosis
S4 S1 S2
It can be remembered as 'Tennessee' or 'a STIFF wall'
I thoroughly recommend this website to listen to them http://www.wilkes.med.ucla.edu/Rubintro.htm
Now away from cardiology and to a bit of pharmacology - sodium valproate....