Heart murmur: types, causes, tests and when to see a doctor

Hearing that you or your child has a heart murmur can be frightening, but it is often harmless. This article explains what a murmur is, why it happens and what tests may follow, using information from MedlinePlus and the NHS.

1. Introduction

A heart murmur is an extra sound heard during a heartbeat. It is caused by turbulent blood flow through the heart valves or near them ^[1]. Valves are the flaps that keep blood moving in one direction through the heart. A murmur is a sign found by a doctor, not a disease in itself. The NHS notes that heart valve disease is sometimes found by chance when a doctor hears a murmur ^[2].

2. Types of murmur

Doctors describe murmurs in several ways ^[1]:

• Loudness. Murmurs are graded from 1 to 6. A very loud murmur, grade 4 or higher, can sometimes be felt through the chest wall.
• Timing. A systolic murmur happens when the heart squeezes blood out. A diastolic murmur happens when the heart fills with blood.
• Innocent or abnormal. Innocent murmurs are harmless, cause no symptoms and need no heart treatment. Abnormal murmurs are linked to a heart problem.

3. Causes and risk factors

MedlinePlus explains that innocent murmurs can occur with exercise, pregnancy, emotional stress, fever, anaemia (a low red blood cell level) and an overactive thyroid ^[1]. In children, common harmless types include flow murmurs, Still's murmur and venous hum, and these need no treatment ^[1].

Abnormal murmurs may be caused by ^{[1, 2]}:

• A valve that leaks backward (regurgitation) or is narrowed or stiff (stenosis)
• A thickened heart muscle, called hypertrophic cardiomyopathy
• Heart valve changes with age, particularly when linked with smoking, high blood pressure or high cholesterol ^[2]
• Damage from conditions such as rheumatic fever, endocarditis (infection inside the heart) or a heart attack ^[2]

In children, a significant murmur is more often linked to a heart defect present from birth, such as a hole between heart chambers ^[1]. The NHS notes that a murmur is common in congenital heart disease ^[3].

4. Signs and symptoms

An innocent murmur causes no symptoms. When a murmur reflects a heart problem, a doctor will ask about symptoms such as chest pain, fainting, shortness of breath, swelling, weight gain, swollen neck veins or bluish skin ^[1]. The NHS lists symptoms of valve disease that include breathlessness, tiredness, dizziness, palpitations, swollen ankles and chest discomfort ^[2]. In babies and children with a heart defect, the NHS describes feeding trouble, slow growth and swelling ^[3].

5. Diagnosis and tests

The doctor listens with a stethoscope. You may be asked to change position or do breathing exercises during the exam, which helps the doctor hear the murmur better ^[1]. Common tests include ^{[1, 2]}:

• A chest X-ray
• An electrocardiogram (ECG), which records the heart's electrical activity
• An echocardiogram, an ultrasound scan that shows the heart and valves working

A doctor may refer you to a heart specialist, called a cardiologist ^[2].

6. Treatment and management

MedlinePlus says innocent murmurs need no heart treatment ^[1]. When a murmur comes from a heart problem, treatment depends on the cause. For valve disease the NHS says people with mild disease and no symptoms usually need only regular check-ups, while those with symptoms or severe disease may need medicines or surgery to repair or replace a valve ^[2]. The NHS says the aortic and mitral valves on the left side of the heart are the ones most often affected, and complications can include heart failure, an irregular heartbeat called atrial fibrillation, stroke and endocarditis ^[2]. For congenital heart disease, the care team decides whether monitoring, medicines or surgery is needed ^[3].

7. Special groups

Pregnancy is one of the situations in which a harmless murmur can appear ^[1]. The NHS advises anyone with valve disease to seek advice from a heart specialist before or during pregnancy, as symptoms can worsen ^[2]. Babies and children with a murmur should be assessed by a doctor, since children's murmurs are sometimes linked to birth heart defects ^[1].

The NHS says valve disease is sometimes found when a doctor hears a murmur during a routine chest exam ^[2]. If you are told you have a murmur, it is reasonable to ask whether it sounds innocent, whether any test is needed and when it should be checked again. Keep a note of any symptoms, such as breathlessness or tiring easily, and tell your doctor.

8. When to see a doctor

See a doctor if you or your child has a murmur together with chest pain, fainting, breathlessness, swelling, bluish skin, or poor feeding and growth in a baby ^{[1, 3]}. The NHS also advises seeing a doctor for regular breathlessness, tiredness or dizziness in daily activities, or palpitations that keep coming back or get worse ^[2]. Call for emergency help for severe breathing difficulty, sudden chest pain that spreads to the arms, back, neck or jaw, or chest pain lasting over 15 minutes. The NHS says not to drive yourself, but to ask someone to drive you or call an ambulance ^[2]. It also says to call for emergency help if a child's lips or skin suddenly turn blue or grey ^[3].

In an emergency, call your local emergency number (112 in India, 911 in the United States).

9. Conclusion

A heart murmur is an extra sound, and many are harmless. Others show a valve problem or a heart defect, so a doctor should assess it and may arrange an ECG or echocardiogram. Follow your doctor's advice on check-ups and treatment.