Heart murmurs (innocent) | Great Ormond Street Hospital
https://www.gosh.nhs.uk/conditions-and-treatments/general-medical-conditions/heart-murmurs-innocent/
Innocent murmurs can sometimes come and go, becoming noisier if the heart is beating fast - after exercise or with a fever - and quieter as a child sleeps. As the years go by, the heart rate slows and the heart grows and lies deeper within the body. The normal bends within the heart become less tight, and an innocent murmur therefore disappears.
DA: 76 PA: 89 MOZ Rank: 12