I realize that I have mentioned heart murmurs in many of my responses, but I’ve never actually described what one is.
Heart murmurs are noises that originate from the heart or nearby great vessels that an examiner can hear with a stethoscope. The murmur is produced by vibrations that are set up by turbulent blood flow through the valves of the heart or nearby vessels. An analogy would be the type of flow and noise generated by a river going through rapids, where the flow is turbulent, compared to a river flowing smoothly, which is not turbulent and produces almost no sound.
Many murmurs that doctors hear are termed functional or innocent, meaning they are not produced by any serious disease of the heart or its valves. These murmurs are usually fairly soft, occur in systole during the contraction period when the flow out of the heart is greatest and they often change or disappear with changes in position. They may be caused by changes in the position of the heart within the chest, and they produce no disease and should not be a cause for worry.
Murmurs that are caused by diseases or malformations of the heart or great vessels are, of course, a more serious problem. When rheumatic fever was common in this country, it frequently scarred the heart valves, especially if someone had multiple attacks of it.
Since rheumatic fever is now an infrequent disease (at least in this country) most murmurs that aren’t functional are caused by congenital heart diseases, degenerative diseases such as mitral valve prolapse (MVP), or calcification of the aortic valve in the elderly — rarely by infections. The diagnosis of heart murmurs has become much more sophisticated, with phonocardiograms that record and analyse the sounds from the heart, echocardiograms, which use cound waves to visualize the parts of the heart and its valves, and Doppler echocardiograms, which can analyze the flow of blood past the valves of the heart.
The echocardiogram is a painless, non-invasive test that is usually the first one ordered if your doctor has any question about whether the murmur is a functional one or comes from some pathology in the heart.