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Marey (1863) introduced a graphic method of recording the apex beat and showed that the main systolic impulse was immediately preceded by a small wave due to atrial systole.Potain (1875) found that the atrial systolic wave was greatly in- creased in hypertensive heart disease, that it could be palpated, and was usually associated with a presystolic (fourth) heart sound.Barlow and Kincaid-Smith (1960), Grayzel (1960), and Parry and Mounsey (1961) have recently drawn attention to the presence of a palpable atrial impulse at the apex in hypertensive heart disease.Large palpable atrial waves giving rise to a double apical impulse have also been described in hypertrophic obstructive cardiomyopathy and they have been demonstrated graphically by means of the apex cardiogram (Boi-
Epstein et al. (Sun,) studied this question.