Based on the History Alone

Based on history alone, one cannot assume that a heart murmur in an asymptomatic patient represents either a normal or a pathologic finding. A careful cardiovascular examination is mandatory, as many young patients with either congenital or acquired heart abnormalities remain asymptomatic.

The presence of an innocent systolic murmur is common in children and young adults. Most of these murmurs reflect high velocity, turbulent blood flow caused by energetic contraction of a young structurally normal heart.

Heart murmurs may also occur in asymptomatic patients who have underlying pathology. A bicuspid aortic valve, for example, occurs in up to two percent of men and a lesser number of women. In most cases, the valve initially functions well, but can be stenotic or regurgitant and cause turbulence and, therefore, a murmur. Hypertrophic obstructive cardiomyopathy may nor manifest itself in childhood and, therefore, can remain asymptomatic. Similarly, rheumatic heart disease can produce mild valve abnormalities and, therefore, no symptoms.

Many other congenital heart defects cause no symptoms, but produce murmurs that can be quite loud. A few examples include a small to moderate size ventricular septal defect, patent ductus arteriosus and pulmonic valve stenosis.