This mid systolic murmur, commonly referred to as Still's murmur, is best heard between the lower left sternal edge and the apex. It is short in duration, mid frequency and crescendo-decrescendo. It has a characteristic musical quality, does not radiate and it is not affected by respiration. It usually decreases in intensity with increased heart rate and with sitting or standing. This distinctive murmur is also called a vibratory or violin string murmur, names designed to emphasize its musical quality.
Still's vibratory murmur
This is a graphic example of a Still's, or vibratory innocent, murmur. Note the harmonic quality of the murmur in the oscilloscopic image. The dominant frequency of the murmur may be lower or higher than in this example, but the other acoustic characteristics do not vary.
Etiology
The Still's vibratory murmur is generated by mild turbulence in the left ventricular outflow tract just proximal to the aortic valve. Recognizing this murmur as innocent obviates additional laboratory procedures. The patient requires no further evaluation or therapy.