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Pressure pulses were obtained under direct vision, in the left atrium of subjects without clinical evidence of cardiac disease and in patients with mitral valvular disease, after exposure of their hearts during the course of surgical intervention. It was found that the c wave is produced by valvular closure and the subsequent fall of pressure during early ventricular systole (x wave) is related to atrial relaxation. Evidence is presented that mitral incompetence cannot be determined from direct atrial recordings, unless the Degrees of insufficiency is of great magnitude.
Ankeney et al. (Sun,) studied this question.