A heart murmur is a whooshing or swishing sound a doctor hears through a stethoscope, occurring between the regular “lub-dub” sounds of the heartbeat. Murmurs are often discovered incidentally during a routine physical examination. While the term can sound alarming, many murmurs are entirely harmless and are simply normal variations of blood flow. However, some do signal an underlying structural problem within the heart that requires further investigation.
What Causes the Murmur Sound
The typical “lub-dub” of a healthy heart is the sound of the four heart valves closing. A heart murmur arises when blood flow becomes turbulent as it moves through the heart or vessels. This unusual flow pattern causes the adjacent soft heart tissues to vibrate, creating the extra whooshing sound.
Murmurs fall into two main categories: innocent and abnormal. Innocent, or functional, murmurs are not caused by heart disease but by temporary conditions that increase the speed of blood flow. These conditions include rapid growth, intense exercise, fever, severe anemia, or the increased blood volume associated with pregnancy. Innocent murmurs are common, especially in children, and typically do not require treatment or lifestyle changes.
Abnormal, or pathological, murmurs are caused by a structural issue within the heart that forces blood to flow incorrectly. The most frequent causes are problems with the heart valves. For example, stenosis occurs when a valve becomes stiff and narrowed, restricting forward blood flow. Alternatively, regurgitation means a valve does not close completely, allowing blood to leak backward. Other structural causes include septal defects, which are holes in the walls separating the heart chambers.
When a Murmur Signals a Serious Heart Condition
An innocent murmur typically causes no symptoms and is only detectable by a stethoscope. When a murmur is pathological, the faulty structure forces the heart to work harder to maintain circulation. This strain eventually leads to noticeable physical symptoms, signaling that the underlying condition is impacting the heart’s ability to pump blood efficiently.
Patients with a serious murmur may experience shortness of breath, particularly during physical activity or when lying flat. A persistent cough that does not resolve with typical remedies is another common sign of reduced heart function, as blood can back up into the lungs, leading to congestion.
Other symptoms that warrant immediate medical attention include lightheadedness, dizziness, or fainting, which may indicate poor blood flow to the brain. Visible swelling (edema) may also occur in the legs, ankles, or abdomen due to fluid retention from inefficient circulation. Unexplained fatigue, heavy sweating with minimal exertion, and chest pain can also accompany a structural heart problem causing an abnormal murmur.
How Doctors Determine the Severity
Determining the significance of a murmur involves a thorough physical exam with a stethoscope. The physician listens carefully to the sound’s timing (systolic or diastolic), pitch, and location. They also grade the murmur’s intensity on a scale of 1 to 6.
A Grade 1 murmur is extremely faint, while a Grade 6 murmur is so loud it can be heard even when the stethoscope is held slightly off the chest wall. The doctor may also check for a “thrill,” a palpable vibration felt on the chest, usually associated with murmurs graded 4 or higher. While a loud murmur does not automatically mean a severe problem, a diastolic murmur of any grade almost always suggests an underlying pathological condition and requires further testing.
To confirm the cause and severity, doctors rely on specialized diagnostic imaging. The echocardiogram, or “echo,” is the primary tool, using sound waves to create moving images of the heart. This test allows the doctor to visualize the structure of the heart chambers and assess how the valves are opening and closing. The echo determines the degree of valve narrowing (stenosis) or leakage (regurgitation) and measures the overall function of the heart muscle.
An electrocardiogram (EKG) may also be used to check the heart’s electrical activity and rhythm. An EKG can reveal signs of strain or enlargement in the heart chambers, suggesting the heart has been working under increased pressure due to the structural defect. These assessments collectively allow the physician to determine the condition causing the murmur and plan appropriate management.
Living with a Heart Murmur Long-Term
The long-term outlook for a person with a heart murmur depends highly on its cause. For the majority of people with an innocent murmur, the prognosis is excellent; the condition does not impact life expectancy, physical activity, or daily life. These murmurs often disappear as a child grows, and even if they persist into adulthood, they require no medical intervention.
For pathological murmurs caused by structural issues, management focuses on addressing the underlying problem. Individuals with mild to moderate valve abnormalities may only need regular monitoring with follow-up echocardiograms to track the condition’s progression. Lifestyle modifications, such as maintaining a heart-healthy diet and engaging in physical activity, are recommended to reduce strain on the cardiovascular system.
When the condition is advanced or symptoms worsen, active treatment becomes necessary. Medications may be prescribed to manage symptoms by controlling blood pressure, regulating heart rhythm, or reducing fluid retention. If valve damage is severe, surgical intervention is often required to prevent long-term complications like heart failure.
Modern surgical options include valve repair, which is generally preferred, or valve replacement, which can be done via open-heart surgery or less invasive procedures. With timely diagnosis and appropriate treatment, individuals with a serious structural defect can often lead a full and active life.