Innocent Murmur
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4 years old girl is referred for cardiac evaluation of a mumur. On examination there is no parasternal lift. She has a 2/6 early systolic murmur best heard between apex and left lower sternal border. It is of low pitch and has a musical quality. It is best heard with bell of the stethoscope. It decreases with Valsalva and becomes prominent on supine position. Her pulses are normal and otherwise she is growing well. Her chest X-Ray and ECG is with in normal range.
What is most appropriate clinical diagnosis?
- Ventricular septal defect
- Atrial septal defect
- Still’s murmur
- Aortic stenosis
The murmur described in this question is consistent with Still’s murmur. It was first described by Still in 1909.
- It is common innocent murmur of childhood and thought to be periodically found in 50-60% of school –aged children.
- They are detected between 3 and 6 years of age, but the same murmur may be present in neonates, infants and adolescents.
- Characteristic of murmur:
- Best heard over mid precordium.
- It is of low frequency and best heard with bell of the stethoscope and patient in supine position.
- Murmur is midsystolic in nature and grade 2-3 by 6 in intensity.
- It is musical in nature.
- It has a distinctive quality described as twanging string or vibratory sound.
- It is not accompanied with thrill or ejection click.
- Intensity may increase during febrile period and in anemic state.
- Origin of murmur remains obscure, following are various theories:
- Physiological narrowing of LVOT
- hypermobility of mitral valve chordae
- LV false tendons
- Low frequency vibrations of pulmonary leaflets
- Important to differentiate it from VSD and HOCM.
- VSD murmur is not affected by physiological maneuvers.
- HOCM murmur gets louder with Valsalva and standing, while reverse happens in cases with Still’s murmur.
Still’s murmur being one of the commonest clinical scenario in pediatric outpatient practice, it is important to understand this phenomenon and clinical implications.