Innocent Murmur


Article Author:
Ernesto Mejia


Article Editor:
Sarita Dhuper


Editors In Chief:
Laurie Graham
Andrew Wilt
Mary Cataletto


Managing Editors:
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Frank Smeeks
Kristina Soman-Faulkner
Benjamin Eovaldi
Radia Jamil
Sobhan Daneshfar
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Hajira Basit
Phillip Hynes


Updated:
5/12/2019 3:13:30 PM

Introduction

Historically, James Hope was one of the first physicians to recommend methods to recognize benign and innocent murmurs. In his 1942 textbook, Hope says “murmurs from these causes may easily be distinguished from that of valvular disease…” As the 20th century approached, it became more common knowledge among the medical community that healthy children and adolescents may have murmurs and gallops on physical exam that have no pathologic significance, especially in the asymptomatic patient. [1]

Etiology

The same physical and physiological principles responsible for pathologic heart murmurs are responsible for innocent heart murmurs. This principle is Turbulent Flow.

Innocent murmurs are heard in settings of:

  • Physiologically increased turbulent flow, as in relatively narrow ventricular outflow tracts, high cardiac output states like anemia, and false tendons in the left ventricle
  • Relative vessel narrowing, as seen with vessels stretching during periods of rapid linear growth
  • With lung expansion after birth as seen in peripheral pulmonic stenosis [2]

Epidemiology

Murmurs are the most common reason for pediatric cardiologist referral and evaluation. There are reports that up to 72% of children will have a murmur at some point during childhood and adolescence, and of these, some may stay present until adulthood, while others will resolve with time. [2] The concern of many practitioners stems from the anxiety of misdiagnosing a benign murmur in the setting of congenital heart disease (CHD). [2]

The incidence of congenital heart disease in the general population is less than 1%, and of all the new murmurs referred to a pediatric cardiologist, less than 1% are a result of CHD. [1]

History and Physical

Evaluation and identification of benign heart murmurs can be done primarily by thorough medical history and focused physical exam. 

History

Neonates and Infants

Conduct a perinatal, prenatal, as well as maternal history if paramount in the evaluation of newborns with heart murmurs. [1] Include: 

  • Maternal age, because advanced maternal age is associated with an increased risk of all heart defects. 
  • History of maternal infections, such as TORCH, with a special focus on rubella infection in the first trimester given its high association with patent ductus arteriosus (PDA), pulmonary valve abnormalities, peripheral pulmonary stenosis, and ventricular septal defects (VSD). 
  • Maternal diabetes mellitus is also of importance due to its association with asymmetric hypertrophic cardiomyopathy.

Postnatal history is just as important, and should focus on feeding difficulties (sweating while feeding), failure to thrive, cyanosis during feeding or activity, respiratory symptoms (tachypnea and increased work of breathing). [1]

Note that grade 2/6 and louder murmurs in the first 24 hours of life are more likely to have an underlying cardiac disease, while lower pitch murmurs in the first, second, or third day of life could be related to changes in pulmonary vascular resistance, a closing PDA, and/or physiological tricuspid regurgitation. [2]

The importance of pre-ductal and post-ductal oxygen saturation in newborns are also an important part of this initial evaluation as differences of less than 3% with overall normal saturations exclude many congenital cardiac pathologies. [3][4][5][6]

Children

In older children and adolescents the above still holds true, however special attention to activity level should be paid. Any patient with a new murmur and decreased activity level, or worsening exercise tolerance (especially compared to peers), or complaints of shortness of breath, chest pain or syncope on exertion should raise major concerns for underlying cardiac pathology. [1]

When assessing exercise tolerance, it is important to do so with an age-appropriate approach. [3]

Physical Exam

General

As with any other patient, it is always important to start the examination of a child who has a murmur by general inspection and not directly with auscultation. The examiner should pay close attention for any dysmorphic features, color changes, respiratory effort, or other congenital anomalies. [1]

Vital Signs

Every patient should have a complete set of vital signs, including blood pressure (BP). [1] If there is already a concern for underlying cardiac disease, then 4-limb blood pressure would be highly recommended. Look for any discrepancies in upper and lower limb blood pressures as this could rule-out in aortic coarctation. Remember that lower limb BP is generally 10 to 20 mm Hg higher than upper limb, and if the upper limb BP is higher, then coarctation needs to be ruled out. [1]

Oxygen saturation is also important. Cyanotic heart lesions may not present at birth, especially ductal-dependent lesions or Tetralogy of Fallot. If intra/extra-cardiac shunting is suspected then upper and lower extremity pulse oximetry should be measured. [3]

Palpation

Palpation of the distal pulses should always be done in cardiac patients. [1] The quality and timing of the pulses can be very important in physical finding associated with certain cardiac lesions. In benign murmurs, the clinicians should be able to feel equal and normal pulses throughout, keeping in mind that physiologically, the femoral pulses should be felt earlier than the brachial pulses in an otherwise normal patient.

Palpation of the chest is also important as it can give you information of cardiomegaly due to a displaced point of maximal impulse (PMI) or a hyperdynamic precordium. [1] Thrills are also important as they will help grade any murmurs (discussed later).

Lastly, palpation of the abdomen is crucial. The abdominal exam may give the examiner insight into the organs of the patient, for example,  situs inversus as well as findings of congestive heart failure such as hepatomegaly. [2]

Auscultation

The auscultatory examination should always be done systematically. The 4 general areas of the cardiac exam (aortic, pulmonary, tricuspid, and mitral) should be examined first, followed by areas of radiation such as the neck, axilla, and back. [1]

Each heart sound should be assessed independently for any abnormalities, clicks, extra sounds, and finally the presence of murmurs.

Special note should be made to the following characteristics of any murmur:

Timing: Systolic versus diastolic. Note than holosystolic/pansystolic murmurs are most often associated with cardiac lesions such as VSD. Purely diastolic murmurs are by definition always pathologic until proven otherwise by echocardiogram or cardiac cath. [1]

Intensity: Grading scale of 1 to 6. Note that a specialist should evaluate any murmur with a grade higher than 3 and consider it pathologic until proven otherwise. [1]

  • Grade 1 is a sound softer than the heart sounds
  • Grade 2 is a sound as loud as the heart sounds
  • Grade 3 is louder the heart sounds
  • Grade 4 is a grade 3 sound plus presence of a palpable thrill
  • Grade 5 is a very loud sound heard with stethoscope barely on the chest
  • Grade 6 is a very loud sound heard with the stethoscope just off the surface of the chest [1]

Location: Location of the murmur on the chest by auscultatory regions mentioned above. The region where the murmur is heard the loudest should be specified here. [1]

Quality: Harsh, blowing, musical, and squeaky. Benign murmurs are most often blowing or musical in quality. [1]

Pitch: Low, Medium, or High. High pitched murmurs are most often pathologic. Most benign murmurs have a low-soft pitch vibratory quality. [1]

Radiation: Murmurs are often heard loudest at one region and softer in others. Areas to which murmurs radiate to should be of note. Specifically radiation to unilateral axillae like in mitral regurgitation, or radiation to neck as in aortic stenosis. [1] Some benign murmurs may also radiate like pulmonary flow murmurs which radiate to the back or peripheral pulmonary artery stenosis which radiate to bilateral axillary lines. [3]

Response to Maneuvers: Pathologic murmurs, especially those of valvular origin will not change in intensity with maneuvers. [1] Other pathologic murmurs such as that from hypertrophic cardiomyopathy may change, but that will not be discussed in this article.

Benign murmurs often do change significantly with position. Specifically of note is the stills/flow murmur which is loudest while the patient is supine given the decrease in afterload seen in this position. [3] Venous hum murmurs also change but in the opposite manner. Venous hums are best heard with the patient sitting up and will most often completely disappear with the patient in the supine position. [3]

One auscultatory finding to keep in mind is that of a flow murmur in the presence of a widely-fixed split S2. The wide-fixed split second heart sound is the most consistent finding of an ASD even without the presence of a systolic ejection murmur.

Types of Benign Murmurs

Systolic Ejection Murmurs

Stills Murmur [3]

  • Most common; usually disappears by adolescence but can persist into adulthood
  • Musical, soft, vibratory low-pitched systolic ejection murmur heard best over left lower sternal border and apex. Grade 1 to 3/6. Loudest when supine. No radiation.

Innocent Pulmonary Flow Murmur [3]

  • Second most common, 
  • Soft, blowing, low-pitched systolic ejection murmur, grade 1 to 3/6, usually heard best over the left upper sternal border and may radiate to the back and axilla.

Peripheral Pulmonary Artery Stenosis [3]

  • Most commonly in the first year of life, especially in premature babies
  • Short, soft, mid-systolic ejection murmur, grade 1 to 2/6, heard best over right/left upper sternal border with radiation to the axilla.

Arterial Supraclavicular Murmur [3]

  • Most commonly seen in late childhood and early adolescence
  • Brief, low-pitched murmur, grade 1 to 3/6, best hear in supraclavicular fossa and may radiate to the neck.

Benign Continuous Murmurs

Venous Hum [3]

  • Most common continuous benign murmur, most often seen between 2 to 8 years of life
  • Soft, whirling, low-pitched murmur, grade 1 to 3/6, heard best in high right sternal border and the right infraclavicular area in the upright position. Murmur does not radiate, disappears completely when supine or when patient extends the neck and turns to the right.

Mammary Souffle [3]

  • Least common, usually heard primarily in young adult women, especially when pregnant or lactating. 
  • Soft, blowing, high-pitched systolic murmur, grade 1 to 2/6, heard best over anterior chest, specifically over the breasts, softer when upright or with high stethoscope pressure.

Evaluation

If a pathologic murmur is suspected, referral to a cardiologist is warranted. [2] Studies have shown that chest x-rays and electrocardiograms have little diagnostic value compared to a specialist’s exam. [3] If a cardiologist remains concerned after his/her exam, the most likely next step would be an echocardiogram for anatomic visualization.[7][8]

Treatment / Management

Benign murmurs tend to resolve with time, though some may still progress onto adulthood never showing any symptoms. When a murmur is deemed benign, there is no need for further clinical monitoring and the patient should live a healthy normal life. It is only important to document such findings as to prevent further stress and unnecessary work-up in the future. It should be noted that no activity restrictions or endocardial prophylaxis are needed as to not deprive the child/patient of any sports or work participation.

Pearls and Other Issues

The medical community should understand the personal and familial anxiety that a murmur classification brings. In the setting of such benign findings, clinicians should strive for better nomenclature of such benign findings as to not increase anxiety and to decrease unnecessary investigation by perhaps renaming “benign murmurs” as innocent flow sounds or benign heart sounds. This might ease the minds of our patients’ and their families and would allow them to participate in everyday activities without impending concerns of possible underlying heart disease in addition to reducing health care costs.

Enhancing Healthcare Team Outcomes

Auscultation is not a very sensitive technique to make a diagnosis of an innocent murmur. When a murmur is detected on a routine physical exam, a thorough patient exam is necessary. The decision to obtain an echo depends on physical findings and patient symptoms. In general, when a patient is designated to have an innocent murmur, close follow up is required to ensure that the murmur either disappears or that no cardiac symptoms develop.[8][9]


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Innocent Murmur - Questions

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Which of the following is not an innocent murmur?



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A 6-year-old female is noted to have a grade II/VI vibratory, midsystolic murmur at the left midsternal border without radiation. The murmur increases in intensity when the patient is supine. What is the most probable diagnosis?



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Innocent systolic murmurs usually are considered to arise in the pulmonic valve. They may also arise in which of the following?



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A male teenager is found to have a supraclavicular systolic murmur that almost disappears when the shoulders are hyperextended. What is the most likely cause?



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A 17-year-old male is seen in the clinic for a suspected murmur. On auscultation, there is a rushing noise between the first and second heart sounds. The noise is quieter than S1 and S2 and best heard near the right upper sternum and is louder with the patient is supine. What should be included in the workup of this murmur?



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A 4-year-old otherwise healthy boy is found to have a new, soft, blowing, grade 2/6, continuous murmur which is heard best at the right infraclavicular area, and with no radiation. The murmur completely disappears when the patient is supine. What is the diagnosis?



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An 18-year-old female recently gave birth to a healthy 40-week baby boy. She is currently breastfeeding only and is here for her regular follow-up. On exam, there is a new, soft, blowing, high-pitched, grade 2/6 continuous murmur heard over the second intercostal space bilaterally that does not radiate. The murmur is best heard with the patient supine and disappears by pressing the stethoscope firmly on the chest. What is the most likely diagnosis?



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A 3 day-old infant is brought for his initial visit. He is a full-term baby boy with an uneventful birth and nursery stay. His mother had full prenatal care with an uncomplicated pregnancy. Today there is a new, 2/6, systolic murmur, located over the left upper sternal border. The murmur radiates to the back and axilla bilaterally. The infant is otherwise healthy. What is the best next step?



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An 8-year-old girl is found to have a new murmur during her yearly well-child visit. The murmur is medium-pitched and best heard over the left upper sternal border, grade 2/6, with a blowing, non-musical quality, and some radiation to the back. The child is otherwise healthy with no acute complaints. What is the most likely diagnosis?



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A 10-year-old girl is evaluated for the first time because she was referred by her provider for a new murmur found on routine health examination. What is the best first step in diagnosing this child?



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Innocent Murmur - References

References

Evaluation and management of heart murmurs in children., Frank JE,Jacobe KM,, American family physician, 2011 Oct 1     [PubMed]
Evaluation of children with heart murmurs., Etoom Y,Ratnapalan S,, Clinical pediatrics, 2014 Feb     [PubMed]
Pediatric cardiology update: Office-based practice of pediatric cardiology for the primary care provider., Abdurrahman L,Bockoven JR,Pickoff AS,Ralston MA,Ross JE,, Current problems in pediatric and adolescent health care, 2003 Nov-Dec     [PubMed]
Reef VB, Assessment of the Cardiovascular System in Horses During Prepurchase and Insurance Examinations. The Veterinary clinics of North America. Equine practice. 2019 Mar 11;     [PubMed]
Ferrara P,Di Ruscio F,Zona M,Ruggiero A, Innocent heart murmurs and enuresis: Examining a possible link. Turkish journal of urology. 2019 Feb 4;     [PubMed]
Ben-Chetrit E,Shavit L,Tvito A,Korem M,Bnaya A, The Devil Is in the Details. The New England journal of medicine. 2019 Feb 7;     [PubMed]
Legget ME,Toh M,Meintjes A,Fitzsimons S,Gamble G,Doughty RN, Digital devices for teaching cardiac auscultation - a randomized pilot study. Medical education online. 2018 Dec;     [PubMed]
Heinemann MK, Heart Murmurs. The Thoracic and cardiovascular surgeon. 2018 Aug;     [PubMed]
Van Oort A,Hopman J,De Boo T,Van Der Werf T,Rohmer J,Daniëls O, The vibratory innocent heart murmur in schoolchildren: a case-control Doppler echocardiographic study. Pediatric cardiology. 1994 Nov-Dec;     [PubMed]

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