A heart murmur is a whooshing or swishing sound heard by a doctor during a heartbeat, differing from the standard “lub-dub” sound of the heart valves closing. This unusual noise is created by turbulent blood flow within the heart or major blood vessels near it. A heart murmur is a physical finding, or a sound, rather than a disease itself. The sound can be temporary and harmless, or it can indicate an underlying structural issue. Whether a heart murmur disappears on its own depends entirely on what causes the turbulent flow.
The Two Categories of Heart Murmurs
Heart murmurs are classified into two main categories: innocent and abnormal. Innocent murmurs, also called functional or physiological murmurs, are harmless and occur when blood flows quickly through a structurally normal heart. These are common in children and are not a sign of heart disease. The turbulence is often a result of a temporary condition that increases the speed of blood flow.
Abnormal, or pathological, murmurs are caused by a structural problem within the heart itself. These murmurs indicate an underlying issue, such as a defect in a heart valve or a hole in the wall separating the heart chambers. In adults, these murmurs are often related to acquired valve disease, while in children they are due to congenital heart defects. The type of murmur detected is the primary factor in determining if it can resolve spontaneously.
When Murmurs Disappear on Their Own
Innocent heart murmurs frequently disappear without medical intervention, most often observed in children and adolescents. As a child grows, the anatomical structures of the heart and chest wall mature, changing the dynamics of blood flow. For example, a relatively narrow ventricular outflow tract in a young child may produce turbulence, but as the child grows and the tract widens, the murmur may vanish.
Temporary conditions that increase the heart’s output can also cause an innocent murmur that resolves once the underlying issue is treated. These conditions include fever, anemia, hyperthyroidism, or strenuous exercise, all of which temporarily increase blood flow velocity. Once the underlying issue is corrected (e.g., fever breaks, anemia is treated, or the person rests), the blood flow returns to normal, and the murmur typically disappears. Innocent murmurs may also be heard during pregnancy or phases of rapid growth, often resolving once the body stabilizes.
Causes of Persistent Heart Murmurs
Abnormal heart murmurs do not resolve spontaneously because they are linked to fixed structural defects. These underlying anatomical issues create a constant source of turbulent blood flow that cannot be corrected by the body alone. A common cause is a problem with the heart valves, which can be narrowed (stenosis) or leaky (regurgitation). In stenosis, the valve cannot open fully, forcing blood through a smaller opening and creating a persistent sound.
Regurgitation occurs when a valve does not close tightly, allowing blood to flow backward into the heart chamber it just left. This backflow, such as in mitral regurgitation, is highly turbulent and produces a continuous murmur. Another category of structural problems includes septal defects, which are holes in the wall separating the heart chambers. Defects like Ventricular Septal Defects (VSDs) and Atrial Septal Defects (ASDs) allow blood to shunt between chambers, causing persistent murmurs that require clinical management or surgical repair.
Medical Management and Monitoring
When a heart murmur is first detected, the initial step involves a thorough physical examination and auscultation to assess the sound’s characteristics. The timing, intensity, pitch, and location of the murmur provide important clues for a cardiologist to determine if it is innocent or abnormal. Diagnostic testing is necessary to definitively classify the murmur and identify any underlying structural issues.
The main diagnostic tool is the echocardiogram, which uses sound waves to create live images of the heart’s valves and chambers, revealing blood flow patterns and structural abnormalities. A chest X-ray may be used to check for an enlarged heart, and an electrocardiogram (ECG) measures the heart’s electrical activity. If tests confirm an innocent murmur, no further follow-up or treatment is typically needed beyond documentation.
If the murmur is classified as abnormal, the approach shifts to regular follow-up with a cardiologist to monitor the condition’s progression. Management for structural murmurs can involve medications, such as beta-blockers or diuretics, to manage symptoms and reduce strain on the heart. For significant valvular disease or large septal defects, intervention may be necessary. This intervention ranges from catheter-based procedures to open-heart surgery for valve repair or replacement.