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Heart Murmurs

What causes a heart murmur?

Heart murmurs may be caused by a number of factors or diseases, including:

  • Defective heart valves

  • Holes in the walls of your heart (atrial septal defect or ventricular septal defect)

  • Pregnancy (increased blood volume)

  • Fever

  • Anemia (a decrease in the red cells in the blood)

What are the different types of murmurs?

All murmurs are analyzed for location, pitch, frequency, and duration. They are also graded according to how loud they are (on a scale of 1 to 6 with 1 being very faint and 6 being very loud).

Types of murmurs include:

  • Systolic murmur. This happens during a heart muscle contraction. Systolic murmurs are divided into ejection murmurs (due to blood flow through a narrowed vessel or irregular valve) and regurgitant murmurs (backward blood flow into one of the chambers of the heart).  

  • Diastolic murmur. This happens during heart muscle relaxation between beats. Diastolic murmurs are due to a narrowing (stenosis) of the mitral or tricuspid valves, or regurgitation of the aortic or pulmonary valves.

  • Continuous murmur. This happens throughout the cardiac cycle.

Online Medical Reviewer: Fetterman, Anne, RN, BSN
Online Medical Reviewer: Gandelman, Glenn, MD, MPH
Date Last Reviewed: 11/1/2016
© 2000-2017 The StayWell Company, LLC. 800 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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