Heart Murmurs

Overview

A heart murmur is an abnormal sound heard through a stethoscope when listening to the heart. In a healthy heart, blood flows quietly through the chambers and valves. A murmur is the sound produced when this flow becomes turbulent for any reason. It may be described as a whooshing, swishing, or blowing noise heard between or instead of the normal heartbeat sounds.

A heart murmur is not a disease. It is a finding. Some murmurs are entirely harmless and do not point to any underlying heart problem. These are called innocent or functional murmurs. Others can be a sign of a heart valve condition, a congenital heart abnormality, or another cardiac problem that requires evaluation and sometimes treatment.

Heart murmurs can be found at any age. Innocent murmurs are very common in children and almost always require no treatment. A murmur newly identified in an adult may warrant closer assessment. Determining whether a murmur is innocent or significant usually involves additional testing.

Types

• Innocent murmurs. These are murmurs heard in hearts with completely normal structure and function. The sound arises from blood moving more quickly or forcefully than usual, not from any abnormality. They are particularly common in children and young people. Situations that increase the heart rate and blood flow, such as fever, anemia, or pregnancy, can make an innocent murmur more audible. No treatment is needed and innocent murmurs often resolve on their own over time.
• Abnormal murmurs. These result from a heart valve condition, a congenital cardiac abnormality, or another underlying heart problem. Identifying the cause and treating it when appropriate is necessary.

Doctors also classify murmurs by when they occur in the heart's cycle. A murmur heard during contraction, when the heart pumps, is called a systolic murmur. One heard during relaxation, when the heart fills, is called a diastolic murmur. Diastolic murmurs are almost always considered abnormal and warrant further investigation.

Symptoms

An innocent heart murmur produces no symptoms at all. The sound is heard only through a stethoscope during examination and the person is entirely unaware of it.

When a murmur reflects an underlying heart condition, symptoms may develop depending on the nature and severity of that condition.

• Shortness of breath. This may occur during physical exertion at first. As an underlying valve condition or congenital heart problem progresses, breathlessness can also develop at rest.
• Fatigue and weakness. When the heart cannot work efficiently, a persistent sense of exhaustion may develop.
• Bluish discoloration of the lips or fingertips. In children particularly, a blue tinge to the lips, fingernail beds, or skin can indicate a serious underlying congenital heart condition in which blood is not being adequately oxygenated.
• Swelling in the legs and ankles. When heart failure develops, fluid can accumulate in the body.
• Palpitations. The heart may feel as though it is racing, fluttering, or beating irregularly.
• Poor growth and development in infants. Babies with significant congenital heart disease may fail to gain weight adequately and show signs of delayed development.
• Chest pain or pressure. Some valve conditions, particularly aortic stenosis, can cause chest discomfort, especially during physical exertion.

When to Seek Medical Care

If a heart murmur is identified during a medical examination, your doctor will advise whether further evaluation is needed. The following situations warrant a medical assessment.

• A heart murmur has been identified for the first time and cardiology evaluation has not yet been arranged
• Shortness of breath during activity or at rest
• Unexplained fatigue or a decline in exercise capacity
• Palpitations or a sensation of irregular heartbeat

Call emergency services immediately if any of the following occur.

• A bluish discoloration of the lips, fingertips, or skin
• Sudden, severe shortness of breath
• Fainting or nearly fainting
• Sudden, severe chest pain

Causes

The causes of a heart murmur differ depending on whether it is innocent or abnormal.

Causes of Innocent Murmurs

In innocent murmurs, the heart is entirely healthy. The sound arises from temporarily faster or more vigorous blood flow rather than from any structural problem.

• Childhood and adolescence. The heart walls are thin and blood flows quickly in young people, making innocent murmurs very common. Most resolve on their own as the child grows.
• Pregnancy. The increase in blood volume and heart rate during pregnancy can produce a temporary murmur that typically disappears after delivery.
• Fever and infections. A high temperature speeds up the heart rate and blood flow, which can temporarily produce a murmur. It often resolves once the fever passes.
• Anemia. A reduction in red blood cells causes blood to flow more rapidly and with greater turbulence. Treating the anemia typically resolves the murmur.
• Hyperthyroidism. An overactive thyroid gland speeds up the heart rate and can contribute to a murmur.

Causes of Abnormal Murmurs

• Heart valve disease. Valve narrowing and leaking are among the most common causes of abnormal murmurs. Each valve condition has a characteristic murmur pattern, and an experienced doctor can often identify which valve is affected and estimate the severity from the sound alone.
• Congenital heart abnormalities. Abnormal connections between chambers or great vessels create turbulent blood flow. A ventricular septal defect (a hole between the heart's two lower chambers) is one of the most common congenital heart abnormalities and produces a characteristic murmur.
• Infective endocarditis. Bacterial infection of the heart valves or inner lining can damage valve structure and produce an abnormal murmur, which may appear or change character during the course of infection.
• Rheumatic heart disease. Untreated streptococcal throat infections can lead to rheumatic fever, which damages heart valves and causes characteristic murmurs.

Diagnosis

A heart murmur is identified during a physical examination. Determining whether it is innocent or abnormal requires further assessment in most cases.

• Physical examination and auscultation. The doctor listens carefully to the heart, assessing the timing of the murmur (whether it occurs during contraction or relaxation) its intensity, its quality, where it is loudest, and whether it spreads to other areas. These characteristics provide highly valuable information about the underlying cause. An experienced clinician can often form a reliable impression of which valve is affected and how significant the problem may be from the murmur's features alone.
• Echocardiogram (heart ultrasound). The most important and most reliable tool for evaluating a heart murmur. It provides real-time images of the heart's structure and function, clearly identifying valve disease, congenital abnormalities, or other cardiac conditions. It is the definitive test for distinguishing an innocent murmur from an abnormal one.
• Electrocardiogram (ECG). Records the heart's electrical activity and can identify changes associated with heart enlargement or rhythm disturbances. It provides supportive information in the overall assessment.
• Chest X-ray. Can show the size of the heart and the appearance of the lung fields.
• Blood tests. Used to investigate whether anemia, thyroid dysfunction, or infection is contributing to the murmur.

Treatment

Innocent heart murmurs require no treatment whatsoever. People with an innocent murmur can live completely normal lives without any restriction.

When a murmur is abnormal, treatment is determined entirely by the underlying cause.

• Valve disease. Treatment depends on the specific valve affected and the severity of the problem. Mild disease may only require monitoring, while more significant disease may need medication, valve repair, or valve replacement.
• Congenital heart abnormalities. Depending on the type and severity of the anomaly, options range from monitoring to catheter-based procedures or surgery.
• Infective endocarditis. The infection is treated first with antibiotics. If significant valve damage results, surgery may be considered.
• Anemia or thyroid disease. Treating the underlying condition typically resolves the murmur without any specific cardiac treatment.

Lifestyle

People with an innocent heart murmur have no restrictions on daily activities. Sport, exercise, and all physical activities can be pursued freely. No special precautions are needed.

For people whose murmur reflects an underlying heart condition, lifestyle recommendations depend on the specific condition. Ongoing cardiology follow-up and adherence to the monitoring plan recommended by the doctor are important.

In both groups, informing dentists and other treating doctors about the murmur or underlying heart condition is worthwhile. In people with certain cardiac conditions, antibiotic coverage before dental procedures may be recommended to reduce the risk of valve infection.