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