[The plateau of the apex cardiogram]

The apex cardiogram should normally include a flat part, but when one looks carefully, one may note that this flat part normally includes a flat wave between the descending part from the first summit and the part rising towards the second summit. This is therefore something which occurs in the middle of systole. Now, quite different curves, such as those of ventricular volume collected by rheography or cineangiography, also show a mesodiastolic occurence. As far as clinical medicine is concerned, it is expressed more frequently during proto or telesystole, rather than during mesosystole, which may be totally free of abnormal waves. What thus occurs in mesosystole? This is the question which is raised by these findings]