[The 6th heart sound]

The author describes a new sound in systole which he calls the V1th heart sound. This sound can be recorded in patients with pure aortic incompetence, but also in healthy subjects. It is not sufficiently loud to be heard on auscultation. It is visible only on the low frequency bands at 35 Hz, and rarely at 70 Hz. It is maximal at the apex and the endapex. It is characterised by 1 or 2 oscillations at the end of mesosystole and at the beginning or middle of end-systole. This sound may be physiological: it will then be of low amplitude, and further from the 2nd sound than in cases of pure aortic incompetence, in which it is pathological, and closer to the 2nd sound. The author puts forward two hypotheses for the origin of the VIth sound.