The possible etiology of the vibratory systolic murmur.
Between January and September 1985, 476 patients underwent two-dimensional and M-mode echocardiography. Left ventricular bands were noted in 104 of these individuals. Of these patients, 89 (85.6%) were referred for evaluation of a systolic murmur. In view of this high incidence of association between left ventricular bands and systolic murmurs, we decided to perform a prospective analysis on patients with the classical vibratory systolic murmur (Still's murmur) which is commonly found in children and young adults. The incidence of left ventricular bands would be compared with a group of individuals in whom no cardiac murmurs could be detected. It was hoped in this way to possibly determine whether there was a definite relationship between the vibratory systolic murmur and left ventricular bands. Echocardiographs were performed using an Advanced Technical Laboratories machine and gain settings were adjusted such that all artefacts and normal structures could easily be distinguished from the ventricular bands. The ventricular bands were divided into two types. Of significance, we felt, were those which crossed the left ventricular outflow tract and which could therefore have been responsible for the production of turbulence and thus a murmur reminiscent of the Still's murmur. This type of left ventricular band was noted in 76% of our patients with Still's murmurs as opposed to only 14% of the individuals without any murmur (p less than 0.001). This statistically significant difference led us to conclude that left ventricular bands might be the cause of the Still's murmur. Further investigation, particularly with Doppler studies would be required to confirm this interesting association.