Heart murmur

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Nuha Al-Howthi, MD[2]

A cardiac murmur is an abnormal heart sound produced as a result of turbulent blood flow, which is sufficient to produce audible noise, defined as a relatively prolonged series of auditory vibrations of varying intensity (loudness), frequency (pitch), quality, configuration, and duration. Murmurs are not characteristic of normal cardiac physiology and may warrant further evaluation, particularly if they occur during diastole. However, murmurs are sometimes “innocent” or benign if they are only due to increased flow across a normal heart structure.

A heart murmur is an unusual sound heard between heartbeats, physicians performed auscultation of the heart by placing their ear directly on the patient’s chest, a technique called “immediate auscultation”. The heart murmurs clearly described in detail by Allan Burns (1781–1813).

Heart murmurs can be classified by seven different characteristics such as their “quality” (blowing, harsh, rumbling, musical), their “pitch” (high, low, or medium), their “intensity” or loudness, their “timing” in the heart cycle (diastolic or systolic), their “shape” or the variation in their intensity over time, their “location” or spot where they are heard best, their “radiation” or where the sound is transmitted to. An example would be the classification of a murmur as “a harsh, rough, low pitched 3/6 systolic ejection murmur at the right upper sternal border that radiates to the carotids” which is consistent with aortic stenosis.

Turbulent flow is responsible for most murmurs. Turbulent flow occurs when the velocity of blood flow becomes critically high because of a high volume of flow, the flow goes through an irregular or narrow area, the flow empties into a dilated vessel or chamber, or if the flow goes backward through an incompetent valve, septal defect, or patent ductus arteriosus. Frequently, a combination of these factors is operative.

The prevalence of heart murmur among neonates varies among different studies, ranging from as low as 0.9 % to 77.4%. According to one study involving 7204 neonates, a murmur was detected in less than 1 % of the neonates. Half of the neonates with heart murmur had cardiovascular malformation. The prevalence of heart murmur among neonates varies among different studies, ranging from as low as 0.9 % to 77.4%. there is a (42.5%) chance that the murmur is due to underlying structural defects.

heart murmur may present as innocent murmurs in one particular area of the precardium or as a pathological murmur, the majority of murmurs in children are innocent and found incidentally. Complication of heart murmur depend on the cause of the murmur for example MR may lead to development of pulmonary edema, pulmonary hypertension, and right heart failure,and in case of aortic valve stenosis can lead to angina, syncope, congestive heart failure, atrial fibrillation, endocarditis, and sudden cardiac death.

Many times, the person experiencing heart murmur may not be aware of anything. But heart murmur can be associated with other things such as tightness in the chest, shortness of breath, dizziness or lightheadedness. Depending on the cause of the murmur, these symptoms may be different.

The physical examination is the initial step to identify the cause and the severity of the valvular pathology causing a heart murmur. Provocative maneuvers such as handgrip (which increases systemic vascular resistance), the Valsalva maneuver (which reduces the return of blood to the right side of the heart), and inspiration (which increase blood return to the right side of the heart) may help to identify the underlying valvular pathology.

In a patient with a heart murmur, a complete blood count (CBC) may be useful in evaluating anemia as a contributing condition, thyroid function tests may be checked to rule out hyperthyroidism, blood cultures may be helpful in excluding endocarditis, and a pregnancy test to exclude pregnancy.

An echocardiogram is the diagnostic study of choice in a patient with a murmur, and should be obtained in asymptomatic patients with diastolic murmurs, continuous murmurs, holo-systolic murmurs, late systolic murmurs, murmurs associated with ejection clicks or murmurs that radiate to the neck or back as well as a grade 3 or louder midpeaking systolic murmur. An echocardiogram should also be obtained in patients with evidence of myocardial infarction or ischemia, heart failure, congenital heart disease, syncope, endocarditis. Echocardiographic evaluation is not recommended in some murmurs, such as a grade 2 or softer mid-systolic murmur, which can be an “innocent”, “benign” or “functional”.

Treatment of a murmur depends upon its underlying cause, the pace of its progression and the associated hemodynamic abnormalities, if any, associated with it.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Nuha Al-Howthi, MD[2]

A heart murmur is an unusual sound heard between heartbeats, physicians performed auscultation of the heart by placing their ear directly on the patient’s chest, a technique called “immediate auscultation”. The heart murmurs clearly described in detail by Allan Burns (1781–1813).

• In February 1818, the application of stethoscope was discovered by Laënnec at the Paris Academy of Sciences,later he published the work De l’auscultation médiate or Traité du Diagnostic des Maladies des Poumon et du Coeur.^[1]
• “Immediate auscultation” is a technique was performed at Hippocrates days, by placing the ear directly on the chest for examining the respiratory system. Instead, it was not appropriate for cardiac examination, as heart sounds were difficult to locate them from small and circumscribed precordial area.^[1]
• In 1816, Laennec was the first to created a paper acoustic device as a stethoscope to examine the chest. This technique “mediate auscultation” ^[1]
• In 1628, William Harvey first treated heart sounds in De Motu Cordis.^[1]
• Harvey, in his “visceral lectures” of 1616, compared heart sounds to “two clacks of a water bellows to rayse water.^{[2] [1]}
• In 1715, James Douglas, fellow of the Royal Society of London, heard severe aortic regurgitation murmur from the patient’s bedside.^[1]
• In 1757, The thrill (“particular vibratory movement”) and a murmur of arteriovenous fistula were described by William Hunter, professor of Anatomy to the Royal Academy, London^[1]
• Heart murmur clearly and in detail were described by Allan Burns, cardiologist and lecturer on anatomy and surgery at Glasgow.^[1]
• Laënnec was the one who teach cardiac auscultation, and in the subsequent years became a crucial component of cardiac physical examination, especially with rheumatic valvular disease.^[1]

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

A heart murmur can be classified based on the various characteristics of the murmur. Quality, pitch, intensity, timing, shape, and location can be used to classify the heart murmur into different categories. From a clinical perspective, a heart murmur can be classified into two important categories: pathologic murmurs, which require further evaluation, and innocent murmurs, which occur due to physiologic changes.

The quality of a murmur can be characterized as:

• Blowing: Mitral regurgitation often has this quality
• Harsh: Aortic stenosis may have this quality
• Rumbling: Mitral stenosis may have this quality
• Musical

The pitch of a murmur is either low, medium, or high. Low pitched murmurs are best heard with the bell of the stethoscope while high pitched sounds are best heard with the diaphragm of the stethoscope.

Intensity refers to the loudness of the murmur, and it is graded on a scale from 0-6/6, with 6 being the loudest. ^[1]

Systolic thrills (palpable murmurs best felt by the tips of the fingers which feel similar to a cat purring) are associated with murmurs of grade 4 or louder. Systolic murmurs of grade 3 or more in intensity are usually hemodynamically significant. ^[2]

The timing of heart murmurs can be broadly classified as either diastolic or systolic ^[3]. Systole is considerably shorter than diastole at normal heart rates. At rapid heart rates, the examiner can usually time the murmur by simultaneous palpation of the lower right carotid artery or can rely on the fact that the S₂ is usually the louder sound at the base. Once S₂ is identified, murmurs can be located properly in the cardiac cycle as systolic or diastolic. The inching technique, popularized by Harvey and Levine, consists of slowly moving the stethoscope down from the base to the apex while repeatedly fixing the cardiac cycle in mind, using S₂ as a reference point. In sinus tachycardia, carotid sinus pressure can temporarily slow the rate and make it possible to differentiate systole from diastole.

• Diastolic heart murmurs are not normal, while systolic heart murmurs may be normal or abnormal
• Diastolic murmurs always require further evaluation
• Systolic murmurs are most often benign and are due to rapid flow rates
• Systolic murmurs are not normal when accompanied by a heave

Shape refers to the intensity over time; murmurs can be crescendo (increasing), decrescendo (diminishing), crescendo-decrescendo (increasing-decreasing or diamond-shaped), and plateau (unchanged in intensity).

Location refers to where the heart murmur is best heard. There are 6 places on the anterior chest to listen for heart murmurs. Each of these locations roughly correspond to a specific part of the heart. The first five out of six are adjacent to the sternum. These locations are:

• 2^nd right intercostal space
• 2^nd left intercostal space
• 3^rd left intercostal space
• 4^th left intercostal space
• 5^th left intercostal space
• 5^th mid-clavicular intercostal space

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Associate Editor(s)-in-Chief: Nuha Al-Howthi, MD[2]

Turbulent flow is responsible for most murmurs. Turbulent flow occurs when the velocity of blood flow becomes critically high because of a high volume of flow, the flow goes through an irregular or narrow area, the flow empties into a dilated vessel or chamber, or if the flow goes backward through an incompetent valve, septal defect, or patent ductus arteriosus. Frequently, a combination of these factors is operative. The sounds most commonly originate from the abnormal movement of blood across valves and between cardiac chambers. When this occurs, turbulence results, which produces vibrations in the chambers of the heart or outflow vessels that are detected as Murmurs.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Nuha Al-Howthi, MD[2]

Causes of heart murmur can be grouped into functional, also known as innocent murmur, physiologic and pathological murmurs. Still murmur is one of the causes of functional murmur. Causes of physiologic murmur include arteriovenous fistula and pregnancy. Pathological murmur can result from a broad variety of conditions such as valvular stenosis, valvular insufficiency, mitral valve prolapse, right-to-left shunt and left-to-right shunt.

• Systolic murmur^[1]
  • Ejection murmurs
    • Functional
      • Still’s murmur and its adult variant
      • Flow murmur emanating from the root of the pulmonary artery
      • Murmur associated with high cardiac output states
      • Flow murmurs associated with aortic or pulmonary valvular insufficiency
    • Organic
      • Valvular aortic stenosis
      • Aortic sclerosis
      • Discrete subvalvular aortic stenosis (web or tunnel)
      • Supravalvular aortic stenosis
      • Hypertrophic obstructive cardiomyopathy
      • Pulmonary valvular stenosis
      • Pulmonary infundibular stenosis
      • Atrial septal defect
      • Tetralogy of Fallot
  • Regurgitant murmurs
    • Functional: none
    • Organic:
      • Mitral regurgitation:
        • Rheumatic
        • Papillary muscle dysfunction
        • Mitral valve prolapse
        • Acute
      • Tricuspid regurgitation:
        • Chronic
        • Acute
      • Ventricular septal defect
        • Roger’s type (small and large)
          • Without pulmonary hypertension
          • With pulmonary hypertension
        • Slitlike
    • Extracardiac sounds simulating systolic heart murmurs
      • Subclavian (supraclavicular/brachiocephalic) Murmur
      • Internal mammary soufflé
      • Carotid artery bruits
      • Coarctation of the aorta
      • Murmurs emanating from a dilated aortic or pulmonary artery root
      • Patent ductus arteriosus with pulmonary hypertension
        
• Diastolic murmur^[2]
  • Aortic regurgitation
  • Pulmonary valve regurgitation
  • Mitral rumble
    • Obstruction to flow
      • Mitral stenosis (rheumatic, congenital)
      • Left atrial myxoma
      • Cor triatriatum
      • Localized pericardial constriction
    • Increased flow
      • Mitral regurgitation
      • Ventricular septal defect
      • Patent ductus arteriousus
      • Complete heart block
  • Tricuspid rumble
    • Obstruction to flow
      • Tricuspid stenosis (rheumatic, Ebstein’s anomoly, carinoid)
      • Right atrial myxoma
      • Localized pericardial constriction
    • Increased flow
      • Atrial septal defect
      • Tricuspid regurgitation
• Continuous murmur ^[3]
  • THORACIC:
    • Precordial
      • Patent ductus arteriosus
      • Coronary arteriovenous fistulas
      • Sinus of Valsalva aneurysm ruptured into right cavities
      • Atrial septal defect associated with abnormalities that cause increased pressure in the left atrium
      • Left coronary artery origin from pulmonary artery anomaly
      • Continuous murmur at intern mammary artery
    • Extra Precordial
      • Coarctation of the aorta
      • Pulmonary atresia
      • Pulmonary arteriovenous fistula
      • Truncus arteriosus
      • Anomalies of origin of the pulmonary artery
  • EXTRATHORACIC:
    • Venous hum
    • Cruveilhier-Baumgarten sindrom
    • Severe arterial stenosis
    • Extrathoracic arteriovenos fistulas

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2] Nuha Al-Howthi, MD[3]

The prevalence of heart murmur among neonates varies among different studies, ranging from as low as 0.9 % to 77.4%. there is a (42.5%) chance that the murmur is due to underlying structural defects.

• The prevalence of heart murmur among neonates varies among different studies, ranging from as low as 0.9 % to 77.4%. According to one study involving 7204 neonates, a murmur was detected in less than 1 % of the neonates. Half of the neonates with heart murmur had cardiovascular malformation.^[1]
• The prevalence of heart murmur is 13.7 per 1000 neonate. there is a (42.5%) chance that the murmur is due to underlying structural defects.^[2]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Associate Editor(s)-in-Chief: Nuha Al-Howthi, MD[2]

The most potent risk factor in the development of heart murmur is depend on the cause of heart murmur. For instance, history of rheumatic fever and untreated streptococcus infection, congenital disorder, radiation (chest radiation), autoimmune diseases (Lupus),pregnanacy.

• Common risk factors in the development of heart murmur include:^[1][2][3]
  • Alcoholism
  • Diabetes
  • Pregnancy
  • Congenital heart defects
  • Endocarditis
  • History of rheumatic fever
  • Uncontrolled hypertension
  • hyperthyroidism
  • pulmonary hypertension

• Less common risk factors in the development of heart murmur include:
  • Poor nutrition.
  • carcinoid syndrome
  • hypereosinophilic syndrome
  • systemic lupus erythematosus,
  • rheumatoid arthritis.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Yazan Daaboul, Serge Korjian ,Nuha Al-Howthi, MD[2]

Cardiac auscultation is a cost-efficient and relatively sensitive test that should always be performed among all neonatal live births. Additionally, screening for heart murmurs is also recommended among school-children and athletes. While murmurs among neonates are always an indication for further investigation, triage of older children and adolescents according to murmur characteristics is required before referral to a pediatric cardiologist.

• Screening of the heart murmurs by physical examination, including cardiovascular examination and cardiac auscultation is recommended in all neonates, because congenital heart disease occurs at a rate of 50-75 per 1000 live births.^[1][2][3]
• Referral should be made in all cases of murmur auscultation among neonates due to high prevalence of congenital heart disease in this age group.
• Sensitivity and specificity of pathological murmur detection among neonates is considered higher than in older age groups.^[4][5]
• Innocent heart murmurs are the most common cause of referral to pediatric cardiologists.
• The risk of pathological murmurs increases with positive family history of cardiac disease, maternal comorbidities during pregnancy, in-utero exposure to medications and alcohol, history of Kawasaki disease or rheumatic fever, and genetic disorders.^[6]
• During screening, the most common pathological heart murmurs auscultated in childhood is the murmur of mitral insufficiency, and corresponding to half of pathological murmurs in this age group.^[7]
• Screening techniques has been well-validated as an adequate technique to assess for heart diseases in children.
• No further work-up is indicated if the diagnosis of innocent murmurs in children and adolescents made by these 4 criteria:
  • No other abnormal physical exam finding
  • Negative review of systems
  • History negative for risks of structural heart disease.
  • Characteristic features of innocent murmurs are met.
• The 7S of Innocent Heart Murmurs. ^[8]
  • Sensitive to change in position and respiration
  • Short duration, not holosystolic.
  • Single, with no association to gallop or clicks
  • Small, limited to one region and does not radiate
  • Soft, low amplitude
  • Sweet, not harsh
  • Systolic.
• Features of Pathological Murmurs^[9][10][11]
  • Holosystolic or diastolic murmur
  • Grade 3 of higher murmur
  • Harsh quality murmur
  • Abnormal S2
  • Peak intensity at upper left sternal border
  • Presence of systolic click
  • Increased intensity in standing position

• According to the 36th Bethesda Conference in 2005^[12], all athletes must undergo pre-participation screening, including a cardiovascular history and physical examination to quality for competitions, in both supine and standing positions to investigate for signs of left ventricular outflow tract obstruction.^[13]
• The 2007 American Heart Association (AHA) currently recommends that a standardized history and physical examination, including assessment for heart murmurs, is performed every 2 years for all high school and college students engaged in sports.^[13]
• Other athletic groups of different ages do not currently have defined guidelines, but according to AHA, the recommendations of high-school and college athletes may also apply to other age groups.^[13]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Nuha Al-Howthi, MD[2]

heart murmur may present as innocent murmrur in one particular area of the precardium or as pathological murmur, the majority of murmurs in children are innocent and found incidentally. Complication of heart murmur depend on the cause of the murmur for example MR may lead to development of pulmonary edema, pulmonary hypertension, and right heart failure,and in case of aortic valve stenosis can lead to angina, syncope, congestive heart failure, atrial fibrillation, endocarditis, and sudden cardiac death.

• heart murmur may present as innocent murmrur or as pathological murmur.
• It may present with symptoms for instance chest pain, breathlessness, or present with signs of cardiac or extra cardiac disease.
• Heart murmurs represent the second most common reason for referral to pediatric cardiologist after asthma.^[1]
• The majority of murmurs in children are innocent and found incidentally.^[1]

• Complication and prognosis of heart murmur depend on the cause, the type and severity of the murmur.^[2] for example mitral regurgitation may lead to development of pulmonary edema, pulmonary hypertension, and right heart failure,and in case of aortic valve stenosis can lead to angina, syncope.
• innocent heart murmur found incidentally and have a good prognosis.

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