When a valve does not close tightly and blood leaks backward (regurgitation)
When blood flows through a narrowed or stiff heart valve (stenosis)
There are several ways in which your doctor 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 - 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.
When a murmur is more noticeable, the doctor may be able to feel it with the palm of the hand over the heart.
Things the doctor 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?
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:
Goldman L. Approach to the patient with possible cardiovascular disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 50.
Sabatine MS, Cannon CP. The history and physical examination: An evidence-based approach. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 12.
Nishimura RA, Otto CM, Bonow RO, et al. 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease. Circulation. 2014;129(23):2440-92.
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, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.