A heart murmur is a sound heard during a heartbeat that differs from the standard “lubb-dupp” rhythm. This extra sound is often described as a whooshing, blowing, or swishing noise heard using a stethoscope. The sound is created by turbulent, or rough, blood flow moving through the heart’s valves or chambers. While concerning, a murmur does not automatically indicate a serious heart condition.
Innocent Versus Pathologic Murmurs
The distinction between a harmless sound and one signaling an underlying problem is the primary way doctors assess a heart murmur. An innocent murmur, also known as a functional or physiological murmur, occurs in a heart with a normal structure. These murmurs are common, especially in children, and may arise temporarily during periods of increased blood flow, such as with a fever, anemia, or pregnancy.
Innocent murmurs are typically soft, change in intensity when a person shifts position, and do not radiate widely across the chest. They usually occur during the heart’s contraction phase, known as systole, and disappear as the underlying temporary condition resolves or as a child grows. Innocent murmurs do not require any treatment or follow-up beyond routine physical examinations.
A pathologic murmur indicates an underlying structural issue within the heart that requires further investigation. These murmurs are often louder, have a harsher quality, and may persist throughout the entire cardiac cycle. A murmur occurring during the heart’s relaxation phase (diastolic murmur) is generally considered an indication of a structural problem. Pathologic murmurs are caused by a permanent flow disturbance, signaling a need for medical attention.
Warning Signs Requiring Immediate Attention
The most direct answer to when a heart murmur is cause for concern lies in the presence of physical symptoms. If a person with a murmur experiences certain signs, it suggests the turbulent blood flow is impacting the heart’s ability to function effectively. Chronic fatigue or a significant decrease in exercise tolerance should prompt a medical evaluation.
Shortness of breath, particularly when performing mild physical activity or when lying flat, is a significant indication that the heart is struggling. Other serious symptoms include episodes of fainting or dizziness (syncope), and chest pain or discomfort. These symptoms should be immediately reported to a healthcare provider.
In infants and young children, signs of a serious problem include failure to gain weight or grow, along with heavy sweating during feeding. Visible signs of poor circulation, such as a bluish or grayish tint to the lips or fingertips (cyanosis), are red flags for both adults and children. Swelling in the ankles, feet, legs, or abdomen (peripheral edema) suggests fluid retention caused by impaired heart function.
Underlying Structural Issues Causing Concern
Pathologic murmurs arise because the heart’s structure is compromised, leading to abnormal blood movement that creates the turbulent sound. The most frequent causes involve the heart’s four valves, which function as one-way doors to direct blood flow. When these valves are too narrow, the condition is called stenosis, which restricts blood flow as it tries to exit the chamber.
The restricted opening forces blood through a smaller space, generating a high-velocity, turbulent sound. Conversely, if a valve does not close completely, blood leaks backward into the previous chamber, a problem called regurgitation. This backflow creates turbulence and prevents efficient forwarding of blood through the circulatory system.
In children, a pathologic murmur is often related to a congenital heart defect, a structural problem present at birth. Examples include holes in the heart walls, such as a ventricular septal defect (VSD) or atrial septal defect (ASD). These holes allow blood to flow between chambers that should be separated, creating a shunting effect and a resulting murmur.
Medical Evaluation and Confirmation
When a concerning murmur is detected, the next step is a detailed medical evaluation to confirm the cause and severity. The physician will consider the murmur’s timing, location, pitch, and loudness, which is graded on a scale of one to six. A louder murmur, generally a Grade 3 or higher, raises suspicion for a structural problem.
The primary tool used to visualize the heart’s structure and function is the echocardiogram, often called an echo. This non-invasive test uses sound waves to create moving pictures of the heart, allowing the doctor to see the valves in action and measure the direction and speed of blood flow. The echo is the most effective way to identify stenosis, regurgitation, or congenital defects.
Additional tests include an electrocardiogram (EKG or ECG), which measures the heart’s electrical activity and can reveal an enlarged heart chamber or an irregular rhythm. A chest X-ray may also be performed to assess the overall size of the heart and check for fluid buildup in the lungs, a sign of heart failure.