A heart murmur is an extra sound that can be heard during chest examination with a stethoscope. The opening and closing of the heart valves produce expected and predictable sounds in individuals with normal heartbeats. Murmurs represent extra sounds caused by turbulent or abnormal flow of blood past a heart valve, in the heart itself or in great vessels (i.e., aorta, pulmonary arteries).
Some murmurs occur strictly from increased flow. For example, pregnant women often have a functional murmur due to a greater blood volume and hyperdynamic metabolism; these are benign. Other murmurs are due to damaged heart valves and represent significant pathology. Damaged valves may either restrict blood flow (stenotic lesions) or allow blood to flow back into the chamber of the heart from which it had just exited (regurgitant lesions). Heart valves can be damaged due to infection, trauma, heart muscle damage (myocardial infarction), or an individual may be born with a structurally abnormal heart valve.
Fitness and Diving Issue
Stenotic lesions, such as aortic and mitral stenosis, restrict efficient blood flow and may have serious consequences during exercise. Significant aortic stenosis places an individual at greater risk for sudden cardiac death while exercising; it is a contraindication for diving. Mitral stenosis also limits the response to exercise and, over a period of time, can result in congestive heart failure.
Regurgitant lesions pose somewhat less of a risk during diving. Over a period of years, the heart will be taxed by the extra work necessary to pump blood, and heart failure may be the long-term result. Divers with these types of heart valve problems may safely participate in diving if they have no symptoms and have normal left ventricular structure and function, as evidenced by an echocardiogram.
For more information on cardiovascular conditions, see the complete article by Dr. James L. Caruso on Cardiovascular Fitness and Diving from the July/August 1999 issue of Alert Diver.