Heart murmur

In medicine, heart murmurs are the "heart sounds caused by vibrations resulting from the flow of blood through the heart. Heart murmurs can be examined by heart auscultation, and analyzed by their intensity (6 grades), duration, timing (systolic, diastolic, or continuous), location, transmission, and quality (musical, vibratory, blowing, etc)."

Prevalence of common valve abnormalities

Valve	Severity	Prevalence
		Males	Females
Mitral	> mild	13%	9%
Tricuspid	> mild	19	19
Aortic	> mild	15	18
Aortic stenosis	Valve velocity > 2.0 m/s	2	1
Aortic sclerosis		33	25

The location of the heart below the thoracic wall.

A diagram of the cardiac cycle is available and helps understand where to listen for different heart murmurs.

Classification

Systolic murmurs

A systematic review by the Rational Clinical Examination addresses the diagnosis of systolic murmurs.

Aortic stenosis

A clinical prediction rule may help detecting moderate to severe aortic valve stenosis (defined as a valve area of 1.2 cm²or less, or a peak instantaneous gradient of 25 mm Hg or greater):

• If the murmur does not radiate to the right neck, moderate aortic stenosis was very unlikely
• If the murmur has at least three of the following signs, moderate stenosis was likely:
  • slow carotid artery upstroke (other studies suggest more than 200 msec is abnormal)
  • reduced carotid artery volume
  • murmur loudest at the second right intercostal space
  • reduced intensity of the second heart sound

Indications for echocardiography

Indications for echocardiography have been formulated by clinical practice guidelines of the American College of Cardiology and the American Heart Association: Class I recommendations

1. "Echocardiography is recommended for asymptomatic patients with diastolic murmurs, continuous murmurs, holosystolic murmurs, late systolic murmurs, murmurs associated with ejection clicks or murmurs that radiate to the neck or back."
2. "Echocardiography is recommended for patients with heart murmurs and symptoms or signs of heart failure, myocardial ischemia/infarction, syncope, thromboembolism, infective endocarditis, or other clinical evidence of structural heart disease."
3. "Echocardiography is recommended for asymptomatic patients who have grade 3 or louder midpeaking systolic murmurs."

Class IIa recommendations

1. "Echocardiography can be useful for the evaluation of asymptomatic patients with murmurs associated with other abnormal cardiac physical findings or murmurs associated with an abnormal ECG or chest X-ray."
2. "Echocardiography can be useful for patients whose symptoms and/or signs are likely noncardiac in origin but in whom a cardiac basis cannot be excluded by standard evaluation."

Class III recommendations

1. "Echocardiography is not recommended for patients who have a grade 2 or softer midsystolic murmur identified as innocent or functional."

Auscultation

Murmurs may be graded by their loudness:

• Grade I - not heard immediately
• Grade II - heard immediately
• Grade III - hear immediately, but louder
• Grade IV - associated with palpable thrill
• Grade V - may be heard with stethoscope partially off the chest
• Grade VI - may be heard with stethoscope off the chest

Bibliography

• Drummond Rennie; David Simel (2008). THE RATIONAL CLINICAL EXAMINATION: EVIDENCE-BASED CLINICAL DIAGNOSIS (Jama & Archives Journals). McGraw-Hill Professional. ISBN 0-07-159030-7. 
• McGee, Steven R. (2007). Evidence-Based Physical Diagnosis. Philadelphia: Saunders. ISBN 1-4160-2898-6. 
• (1990) Walker HK, Hall WD, Hurst JW: Clinical methods: the history, physical, and laboratory examinations (in English), 3rd. London: Butterworths. LCC RC71 .C63. ISBN 0-409-90077-X.  Library of Congress

See also

• Heart sound