Murmurs are extra heart sounds

Heart sounds

Heart sounds, or heartbeats, are the noises generated by the beating heart and the resultant flow of blood through it...

 that are produced as a result of turbulent blood flow that is sufficient to produce audible noise. Most murmurs can only be heard with the assistance of a stethoscope

Stethoscope

The stethoscope is an acoustic medical device for auscultation, or listening to the internal sounds of an animal body. It is often used to listen to lung and heart sounds. It is also used to listen to intestines and blood flow in arteries and veins...

 ("on auscultation

Auscultation

Auscultation is the term for listening to the internal sounds of the body, usually using a stethoscope...

").

A functional murmur or "physiologic

Physiology

Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...

 murmur" is a heart murmur that is primarily due to physiologic conditions outside the heart, as opposed to structural defects in the heart itself. Functional murmurs are benign (an "innocent murmur").

Murmurs may also be the result of various problems, such as narrowing or leaking of valves

Heart valve

A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...

, or the presence of abnormal passages through which blood flows in or near the heart. Such murmurs, known as pathologic murmurs, should be evaluated by an expert.

Heart murmurs are most frequently categorized by timing, into systolic heart murmur

Systolic heart murmur

Systolic heart murmurs are heart murmurs heard during systole.They can be classified by when the murmur begins and ends, between S1 and S2.Many involve stenosis of the semilunar valves or regurgitation of the atrioventricular valves.-Types:...

s and diastolic heart murmur

Diastolic heart murmur

Diastolic heart murmurs are heart murmurs heard during diastole.Diastolic murmurs start at or after S2 and end before or at S1.Many involve stenosis of the atrioventricular valves or regurgitation of the semilunar valves.-Types:...

s. However, continuous murmurs

Continuous murmurs

Heart murmurs are most frequently organized by timing, into systolic heart murmurs and diastolic heart murmurs. However, continuous murmurs can not be directly placed into either category....

 cannot be directly placed into either category.

Classification

Murmurs can be classified by seven different characteristics: timing, shape, location, radiation, intensity, pitch and quality.

• Timing refers to whether the murmur is a systolic
  Systole (medicine)
  Systole is the contraction of the heart. Used alone, it usually means the contraction of the left ventricle.In all mammals, the heart has 4 chambers. The left and right ventricles pump together. The atria and ventricles pump in sequence...
  
   or diastolic
  Diastole
  Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
  
   murmur.
• Shape refers to the intensity over time; murmurs can be crescendo, decrescendo or crescendo-decrescendo.
• Location refers to where the heart murmur is usually auscultated
  Auscultation
  Auscultation is the term for listening to the internal sounds of the body, usually using a stethoscope...
  
   best. There are six places on the anterior chest to listen for heart murmurs; each of the locations roughly corresponds to a specific part of the heart. The first five of the six locations are adjacent to the sternum. The six locations are:
  • the 2nd right intercostal space
    Intercostal space
    The intercostal space is the space between two ribs . Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it.-Structures in intercostal space:* several kinds of intercostal muscle...
    
    
  • the 2nd to 5th left intercostal spaces
  • the 5th left mid-clavicular intercostal space.
• Radiation refers to where the sound of the murmur radiates. The general rule of thumb is that the sound radiates in the direction of the blood flow.
• Intensity refers to the loudness of the murmur, and is graded on a scale from 0-6/6.
• Pitch can be low, medium or high and is determined by whether it can be auscultated best with the bell or diaphragm of a stethoscope
  Stethoscope
  The stethoscope is an acoustic medical device for auscultation, or listening to the internal sounds of an animal body. It is often used to listen to lung and heart sounds. It is also used to listen to intestines and blood flow in arteries and veins...
  
  .
• Quality refers to unusual characteristics of a murmur, such as blowing, harsh, rumbling or musical.

The use of two simple mnemonics may help differentiate systolic and diastolic murmurs; PASS and PAID. Pulmonary and aortic stenoses are systolic while pulmonary and aortic insufficiencies (regurgitation) are diastolic. Mitral and tricuspid defects are opposite.

Grading of murmurs

Grading of Murmurs
Grade	Description
Grade 1	Very faint
Grade 2	Soft
Grade 3	Heard all over the precordium
Grade 4	Loud, with palpable thrill (i.e. a tremor or vibration felt on palpation)
Grade 5	Very loud, with thrill. May be heard when stethoscope is partly off the chest.
Grade 6	Very loud, with thrill. May be heard with stethoscope entirely off the chest.

Interventions that change murmur sounds

• Inhalation
  Inhalation
  Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....
  
   leads to drop in intrathoracic pressure, which increases capacity of pulmonary circulation
  Pulmonary circulation
  Pulmonary circulation is the half portion of the cardiovascular system which carries Oxygen-depleted Blood away from the heart, to the Lungs, and returns oxygenated blood back to the heart. Encyclopedic description and discovery of the pulmonary circulation is widely attributed to Doctor Ibn...
  
  , thereby prolonging ejection
  Ejection fraction
  In cardiovascular physiology, ejection fraction is the fraction of Blood pumped out of the Right Ventricle of the heart to the Pulmonary Circulation and Left Ventricle of the heart to the Systemic Circulation with each Heart beat or Cardiac cycle...
  
   time. This will affect the closure of the pulmonary valve
  Pulmonary valve
  The pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the...
  
  . This finding, also called Carvallo's maneuver, has been found by studies to have a sensitivity of 100% and a specificity of 80% to 88% in detecting murmurs originating in the right heart. specifically positive Carvallo's sign describes the increase in intensity of a tricuspid regurgitation murmur with inspiration.
• abrupt standing
  Standing (position)
  Standing is a human position in which the body is held upright and supported only by the feet, referred to as an orthostatic state.Although quiet standing appears to be static, modern instrumentation shows it to be a process of rocking from the ankle in the sagittal plane...
  
  
• squatting
• valsalva maneuver
  Valsalva maneuver
  The Valsalva maneuver or Valsalva manoeuvre is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut...
  
  . One study found the valsalva maneuver
  Valsalva maneuver
  The Valsalva maneuver or Valsalva manoeuvre is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut...
  
   to have a sensitivity of 65%, specificity of 96% in detecting hypertrophic obstructive cardiomyopathy (HOCM). Both standing and Valsalva maneuver will decrease venous return and subsequently decrease left ventricular filling, resulting in an increase in the loudness of the murmur of hypertrophic cardiomyopathy, since outflow obstruction is increased by decreasing preload. Alternatively, squatting increases venous return and thus decreases the murmur. Maximum handgrip exercise also results in a decreased loudness of the murmur.
• hand grip
• post ectopic potentiation
• amyl nitrite
  Amyl nitrite
  Amyl nitrite is the chemical compound with the formula C5H11ONO. A variety of isomers are known, but they all feature an amyl group attached to the nitrito functional group. The alkyl group is unreactive and the chemical and biological properties are mainly due to the nitrite group...
  
  
• methoxamine
  Methoxamine
  Methoxamine is an α1-adrenergic receptor agonist, similar in structure to phenylephrine and 2,5-DMA. It was Developed by Burroughs-Wellcome in the 1940s. The drug induces vasoconstriction of skin and splanchnic blood vessels, thereby increasing peripheral vascular resistance and raising mean...
  
  
• positioning of the patient. That is, putting patients in the left lateral position will allow a murmur in the mitral valve
  Mitral valve
  The mitral valve is a dual-flap valve in the heart that lies between the left atrium and the left ventricle...
  
   area to be more pronounced.

Examples of anatomic source of murmur

Stenosis

Aortic valve stenosis

Aortic valve stenosis is a disease of the heart valves in which the opening of the aortic valve is narrowed. The aortic valve is the valve between the left ventricle of the heart and the aorta, which is the largest artery in the body and carries the entire output of blood.-Pathophysiology:The...

 of Bicuspid aortic valve

Bicuspid aortic valve

A bicuspid aortic valve is most commonly a congenital condition of the aortic valve where two of the aortic valvular leaflets fuse during development resulting in a valve that is bicuspid instead of the normal tricuspid configuration. Normally the only cardiac valve that is bicuspid is the mitral...

Symptoms tend to present between 40 and 70 years of age.

Stenosis of Tricuspid Aortic Valve

Symptoms more likely to present after 80 years of age.

Hypertrophic subaortic stenosis:

Symptoms are a harsh murmur in mid-systole, often accompanied by S4, Brisk Bifid Carotid upstroke. Murmur increases with standing and valsalva maneuver.

Ventricular septal defect

Symptoms are holosystolic, heard best at left lower sternal border.

Cooing dove murmur

The cooing dove murmur is a cardiac murmur with a musical quality (high pitched - hence the name) and is associated with acute mitral valve regurgitation, preceded by a rupture of the chordae tendinea (the fibrous "strings" that connect the papillary muscle to the cusps of the valves). It is a systolic murmur which is best heard over the left second, third and fourth intercostal spaces.

External links

• Information on heart murmurs in children from Seattle Children's Heart Center
• Heart Murmurs in Pediatric Patients
• Lehrer, Steven. Understanding Pediatric Heart Sounds
  Understanding Pediatric Heart Sounds
  Understanding Pediatric Heart Sounds 2nd edition by Steven Lehrer is a book and audio CD that guides the student through the skills of pediatric heart auscultation. It provides a complete overview of pediatric heart examination, anatomy, physiology, and pathology. The audio CD presents and...
  
  . Elsevier 2002.
• Hanifin, Christopher. Heart Sounds: A Cardiac Auscultation Primer. CreateSpace, 2010
• Texas Heart Institute Scroll down to listen to heart murmurs.
• The Auscultation Assistant Provides recordings of heart murmurs.