A heart murmur is an extra sound heard during a heartbeat, distinct from the typical “lub-dub” sounds of the heart valves closing. It is a sound, rather than a disease itself, and can be detected by a healthcare provider using a stethoscope. Many people have heart murmurs, which are often harmless.
Understanding Heart Murmurs
Heart murmurs are described as whooshing or swishing sounds. These sounds arise from turbulent blood flow within or near the heart, which differs from the smooth, laminar flow that produces normal heart sounds. The precise characteristics of a murmur, such as its pitch, duration, and timing, help medical professionals understand its origin.
Murmurs can be categorized based on when they occur during the cardiac cycle. Systolic murmurs happen when the heart muscle contracts and pumps blood out. Diastolic murmurs, conversely, are heard when the heart relaxes between beats and fills with blood. Continuous murmurs, a third category, are present throughout both phases of the heartbeat.
Prevalence Across Populations
Heart murmurs are a common finding, with their prevalence varying significantly between different age groups. In children, heart murmurs are frequent, with estimates indicating that up to 72% may experience an innocent murmur during childhood and adolescence. These childhood murmurs are often described as “innocent” or “functional,” meaning they are harmless and typically resolve as the child grows, though some may persist into adulthood.
In adults, heart murmurs are less prevalent than in children, but still a notable occurrence. Approximately 10% of adults are estimated to have a heart murmur. While innocent murmurs can occur in adults, particularly during conditions like pregnancy, fever, or strenuous exercise, new murmurs detected in adults are more likely to indicate an underlying heart condition.
Underlying Causes
Heart murmurs are broadly categorized into two types: innocent (or functional) and abnormal (or pathological). Innocent murmurs do not signify a heart problem, often resulting from normal blood flow variations or high cardiac output states. They can be heard during periods of rapid growth in children, or in individuals experiencing fever, anemia, hyperthyroidism, or pregnancy, all of which can temporarily increase blood flow.
Abnormal heart murmurs, conversely, point to an underlying heart condition that warrants further investigation. In adults, these are frequently linked to issues with heart valves, such as narrowing (stenosis) or leakage (regurgitation). Specific examples include aortic valve stenosis, where the aortic valve becomes stiff and narrowed, or mitral valve regurgitation, where blood flows backward through the mitral valve. Abnormal murmurs in children are more often due to congenital heart defects, which are structural problems present at birth. These can include holes in the heart walls, such as atrial septal defects or ventricular septal defects, or abnormal connections between major blood vessels.
Diagnosis and Management
If a heart murmur is detected during a physical examination, a healthcare provider will listen to the heart with a stethoscope, noting the murmur’s volume, location, pitch, and timing to help determine its nature. Based on these characteristics, further diagnostic tests may be recommended to ascertain if the murmur is innocent or if it signals an underlying heart condition.
The primary diagnostic tool used to evaluate heart murmurs is an echocardiogram, which uses sound waves to create detailed images of the heart’s structure and blood flow. Other tests, such as an electrocardiogram (ECG) to measure electrical activity or a chest X-ray to assess heart size, may also be used. Innocent heart murmurs require no specific treatment. If an abnormal murmur is diagnosed, management depends on the underlying cause and severity; this may involve monitoring, medications to manage symptoms like high blood pressure or fluid retention, or in some cases, surgical interventions to repair or replace a heart valve or correct a congenital defect.