An innocent murmur is commonly found in children and usually disappears as the child grows older. Here, the heart with its valves is absolutely normal. Possible mechanisms are :
- Hyperkinetic circulatory states in children due to increased heart rate, and
- Increased resistance of the pulmonary vascular bed in children.
Table of Contents
Key feature of Innocent Murmur
- Soft
- Systolic
- Short
- Sounds (S1 and S2) normal
- Symptomless
- Special tests normal (X-ray, EKCG)
- Standing/Sitting (vary with position)
What is not an Innocent Murmur?
Learn more about innocent murmur vs pathological murmur
- Diastolic murmurs
- Loud murmurs, grade IV or above
- Regurgitant (pansystolic) murmurs
- Murmurs associated with a click
- Murmurs associated with other signs or symptoms (e.g. cyanosis)
- Abnormal second heart sound (fixed split or single)
Types of Innocent Murmurs
Pulmonary ejection murmur
- It is high pitched and is best heard with diaphragm of the stethoscope in the second left intercostal space (pulmonary area) with radiation to lower left sternal border and apex.
- The murmur is usually ejection systolic and is heard at the beginning of systole or mid-systole.
- It is heard more clearly in situations of increased cardiac output such as fever, anxiety, acute disease and post-exercise.
- Most common in children and adolescents aged between 8 and 14, particularly those with pectus excavatum or kyphoscoliosis.
Vibratory murmur or Still’s murmur
- Found in many school age children.
- Best heard at the lower left sternal border or apex with wide radiation.
- Murmur is usually ejection systolic or early systolic with a musical or twanging quality. It increases with the patient lying down and decreases in the erect posture.
- The murmur might disappear on extension of the neck.
Supraclavicular arterial bruit
- Best heard on the right side of the neck and louder above the clavicle than below it.
- The murmur is usually ejection systolic or early systolic.
- Murmur is mostly found in adolescents and young adults, and is low-pitched and low intensity
Venous hum (jugular venous hum; cervical venous hum).
- Best heard at the root of the neck over the medial part of the supraclavicular fossa (just lateral to SCM) with the head turned in the opposite direction.
- A continuous murmur that increases on sitting up.
Mammary souffle
- Best heard at the right or left sternal border, extending from 2nd to 4th intercostal spaces.
- Continuous murmur with systolic accentuation.
- Occurs during late pregnancy and lactation.
Read more about How to describe a murmur
References
- https://www.ncbi.nlm.nih.gov/pubmed/22010618
- Medicine: Prep Manual for Undergraduates, 3/e