Definition

A heart murmur is a sound made by turbulent blood flow in the heart. It sounds like whooshing or swishing with each heartbeat. Some adults and many children have incidental heart murmurs that are benign (harmless) and are not caused by abnormalities in the heart. However, some heart murmurs can signal an underlying heart problem.

Causes

Benign murmurs are caused by the normal flow of blood through the heart and large vessels near the heart. The murmur may come and go over time. Some things that can increase blood flow and cause a benign heart murmur to be heard include:

• Exercise
• Pregnancy
• Extreme anxiety
• Anemia
• Fever
• Hyperthyroidism

Abnormal heart murmurs can be due to:

• Structural abnormalities of the heart valves (most common)—these may be congenital (present from birth) or acquired later in life. Examples include:
  • Mitral stenosis
  • Mitral regurgitation
  • Aortic stenosis
  • Aortic regurgitation
  • Tricuspid stenosis
  • Tricuspid regurgitation
  • Pulmonary stenosis
• Abnormal holes or connections in the structure of the heart or vessels persisting after birth:
  • Septal defects —connection between the heart’s chambers
  • Patent ductus-arteriosus —connection between the major artery and vein near the heart
• Structural abnormality of the heart muscle:
  • Congenital defects such as hypertrophic cardiomyopathy
  • Acquired such as myocardial infarction, heart failure, and long-standing high blood pressure
• Other congenital heart conditions, such as:
  • Coarctation of the aorta
  • Hypoplastic left heart syndrome
  • Ebstein’s anomaly
  • Tetralogy of Fallot
• Endocarditis —infection of the inner lining of heart valves and chambers (endocardium)
• Rheumatic fever—inflammation and damage of the heart valves from poorly treated strep throat
• Cardiac myxoma—a benign soft tumor within the heart (rare)

Risk Factors

Normal heart murmurs are more common in children 3-7 years old. Pregnant women are also at increased risk.

Risk factors for abnormal heart murmurs include:

• Rheumatic fever
• Atherosclerosis
• High blood pressure
• Autoimmune disease
• Congenital heart defects or disease

Symptoms

Benign heart murmurs usually cause no symptoms. Patients with mitral valve prolapse sometimes complain of vague chest discomfort and other symptoms. It remains unclear whether or not the valvular abnormality is causing the symptoms.

Signs and symptoms of abnormal heart murmurs can include:

• Rapid breathing or trouble breathing
• Blue lips (cyanosis)
• Lightheadedness
• Chest pain
• Rapid or irregular heartbeat
• Exercise intolerance
• Inability to gain weight in children

Diagnosis

Most benign heart murmurs are diagnosed during the course of a routine physical exam with a stethoscope. Some abnormal heart murmurs are also discovered this way. Other abnormal heart murmurs are discovered initially by their symptoms.

Your bodily fluids may be tested. This can be done with blood tests.

Images may be taken of your heart. This can be done with:

• Chest x-ray
• Cardiac catheterization
• Echocardiogram —to examine the size, shape, and motion of the heart.

Your heart’s electrical activity may be tested. This can be done with electrocardiogram (ECG).

Treatment

Benign heart murmurs do not require treatment. Treatment of other heart murmurs depends on the underlying cause and extent of the problem.

Treatments include:

Prevention

Preventing benign heart murmurs is unnecessary. To help reduce your risk of developing an abnormal heart murmur:

• Get prompt testing and treatment for strep throat to prevent rheumatic fever.
• Reduce your risk of atherosclerosis to help prevent valvular heart disease in the distant future. To do this:
  • Eat a healthy diet with plenty of fruits and vegetables.
  • Get regular exercise.
  • If you smoke, talk to your doctor about ways to quit.
  • If you have high blood pressure or diabetes, follow your treatment plan.

Although not routinely recommended for every type of heart murmur, you may need to take antibiotics before and after some medical or dental procedures that could allow bacteria to enter your bloodstream. Ask your doctor if you need to take preventive antibiotics.

CardioSource—American College of Cardiology http://www.cardiosource.org

The College of Family Physicians of Canada http://www.cfpc.ca

Heart murmurs. American Heart Association website. Available at:
http://www.heart.org/HEARTORG/Conditions/More/CardiovascularConditionsofChildhood/Heart-Murmurs_UCM_314208_Article.jsp.Updated
September 3, 2014. Accessed September 30, 2014.

Heart murmurs and your child. Kids Health—Nemours Foundation website. Available at:
http://kidshealth.org/parent/medical/heart/murmurs.html
Updated May 2013. Accessed September 30,2014.

Heart murmur in children. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated December 14, 2012. Accessed September 30, 2014.