Saturday, February, 11, 2012

Heart murmurs and other sounds

Table of Contents

  • 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 - 6).
  • Murmurs may be described as blowing, whooshing, or rasping.
  • 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.

When a murmur is more prominent, the doctor may be able to feel it with the palm of the hand over the heart.

The following are important clues to the cause of the murmur:

  • Does the murmur occur in the resting stage (diastole) or contracting stage (systole)?
  • Does it occur early or late in the stage?
  • Does it last throughout the heartbeat?
  • Does it change when the doctor uses physical maneuvers?
  • Can the murmur be heard in other parts of the chest, on the back, or in the neck?
  • Where is the murmur heard the loudest?

For example, a presystolic murmur is heard just before systole. It is usually caused by narrowing of the mitral or tricuspid valve (the valves between the atria and the ventricles).


Common Causes

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

Significant murmurs can be caused by:

  • Aortic regurgitation
  • Aortic stenosis
  • Hypertrophic cardiomyopathy (idiopathic hypertrophic subaortic stenosis)
  • Mitral regurgitation - acute
  • Mitral regurgitation - chronic
  • Mitral stenosis
  • Pulmonary regurgitation (backflow of blood into the right ventricle, caused by failure of the pulmonary valve to close completely)
  • Pulmonary stenosis
  • 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)

Children often have murmurs as a normal part of development. These murmurs do not require treatment, and may include:

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

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Review Date: 06/05/2010
Reviewed By: Issam Mikati, MD, Associate Professor of Medicine, Feinberg School of Medicine, Director, Northwestern Clinic Echocardiography Lab, Northwestern University, Chicago, IL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)