Definition

A heart murmur is a blowing, whooshing, or rasping sound heard during a heartbeat. The sound is caused by turbulent (rough) blood flow through the heart valves or near the heart.

Alternative Names

Chest sounds - murmurs; Heart sounds - abnormal; Murmur - innocent; Innocent murmur; Systolic heart murmur; Diastolic heart murmur

Considerations

The heart has 4 chambers:

  • Two upper chambers (atria)
  • Two lower chambers (ventricles)

The heart has valves that close with each heartbeat, causing blood to flow in only one direction. The valves are located between the chambers.

Heartbeat

The heart is a four-chambered organ with four main vessels, which either bring blood to or carry blood away from the heart. The four chambers of the heart are the right atrium, the right ventricle, the left atrium, and the left ventricle. The great vessels of the heart include the superior and inferior vena cava, which bring blood from the body to the right atrium, the pulmonary artery, which transports blood from the right ventricle to the lungs. The last of the great vessels is the aorta, the body's largest artery, which transports oxygen-rich blood from the left ventricle to the rest of the body. If we remove some of the tough fibrous coating of the heart and great vessels, you can get a better look at the heart beating. If you look carefully, you can see a series of one-way valves that keep the blood flowing in one direction. If we inject dye into the superior vena cava, you can watch it pass through the heart as it goes through the cardiac cycle. The blood first enters the heart into the right atrium. Blood passes from the right atrium through the tricuspid valve and into the right ventricle. When the right ventricle contracts, the muscular force pushes blood through the pulmonary semilunar valve into the pulmonary artery. The blood then travels to the lungs, where it receives oxygen. Next, it drains out of the lungs via the pulmonary veins, and travels to the left atrium. From the left atrium, the blood is forced through the mitral valve into the critically important left ventricle. The left ventricle is the major muscular pump that sends the blood out to the body systems. When the left ventricle contracts, it forces the blood through the aortic semilunar valves and into the aorta. From here, the aorta and its branches carry blood to all the tissues of the body.

Murmurs can happen for many reasons, such as:

  • When a valve does not close tightly and blood leaks backward (regurgitation)
  • When blood flows through a narrowed or stiff heart valve (stenosis)
Heart valves

There are several ways in which your health care provider may describe a murmur:

  • Murmurs are classified ("graded") depending on how loud the murmur sounds with a stethoscope. The grading is on a scale. Grade I can barely be heard. An example of a murmur description is a "grade II/VI murmur." (This means the murmur is grade 2 on a scale of 1 to 6).
  • In addition, a murmur is described by the stage of the heartbeat when the murmur is heard. A heart murmur may be described as systolic or diastolic. (Systole is when the heart is squeezing out blood and diastole is when it is filling up with blood.)

When a murmur is more noticeable, the provider may be able to feel it with the palm of the hand over the heart. This is called a "thrill".

Things the provider will look for in the exam include:

  • Does the murmur occur when the heart is resting or contracting?
  • Does it last throughout the heartbeat?
  • Does it change when you move?
  • Can it be heard in other parts of the chest, on the back, or in the neck?
  • Where is the murmur heard the loudest?

Causes

Many heart murmurs are harmless. These types of murmurs are called innocent murmurs. They will not cause any symptoms or problems. Innocent murmurs DO NOT need treatment.

Other heart murmurs may indicate an abnormality in the heart. These abnormal murmurs can be caused by:

  • Problems of the aortic valve (aortic regurgitation, aortic stenosis)
  • Problems of the mitral valve (chronic or acute mitral regurgitation, mitral stenosis)
  • Hypertrophic cardiomyopathy (idiopathic hypertrophic subaortic stenosis)
  • Pulmonary regurgitation (backflow of blood into the right ventricle, caused by failure of the pulmonary valve to close completely)
  • Pulmonary valve stenosis
  • Problems of the tricuspid valve (tricuspid regurgitation, tricuspid stenosis)

Significant murmurs in children are more likely to be caused by:

  • Anomalous pulmonary venous return (an abnormal formation of the pulmonary veins)
  • Atrial septal defect (ASD)
  • Coarctation of the aorta
  • Patent ductus arteriosus (PDA)
  • Ventricular septal defect (VSD)

Multiple murmurs may result from a combination of heart problems.

Children often have murmurs as a normal part of development. These murmurs DO NOT need treatment. They may include:

  • Pulmonary flow murmurs
  • Still's murmur
  • Venous hum

What to Expect at Your Office Visit

A provider can listen to your heart sounds by placing a stethoscope on your chest. You will be asked questions about your medical history and symptoms, such as:

  • Have other family members had murmurs or other abnormal heart sounds?
  • Do you have a family history of heart problems?
  • Do you have chest pain, fainting, shortness of breath, or other breathing problems?
  • Have you had swelling, weight gain, or bulging veins in the neck?
  • Does your skin have a bluish color?

The provider may ask you to squat, stand, or hold your breath while bearing down or gripping something with your hands to listen to your heart.

The following tests may be done:

  • Chest x-ray
  • Electrocardiogram (ECG)
  • Echocardiography

References

Fang JC, O'Gara PT. History and physical examination: an evidence-based approach. In: Zipes DP, Libby P, Bonow RO, Mann DL, Tomaselli GF, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 11th ed. Philadelphia, PA: Elsevier; 2018:chap 10.

Goldman L. Approach to the patient with possible cardiovascular disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 51.

Nishimura RA, Otto CM, Bonow RO, et al. 2017 AHA/ACC Focused update of the 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2017;135(25):e1159-e1195. PMID: 28298458 www.ncbi.nlm.nih.gov/pubmed/28298458.

Version Info

  • Last reviewed on 5/16/2018
  • Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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