dias'ter. -faster, See star.]amphiaster. [Gr., dis, twice, diastole (di-as'to-le)

Dilatation, especially that of the cavities of the heart, which occurs alternately with their systole, auricular d. The dilatation of the auricle of the heart by the inflowing blood from the veins; it is almost or entirely a pa ive act, and comprises four-fifths of the time of an entire cardiac cycle or revolution, cardiac d. The expansion of the heart after a contraction by the filling of cavities with blood, ventricular d. The dilatation of the ventricles of the heart; this is brought about by the relaxation of the ventricular walls, the inflow of venous blood from the auricles, and, finally, by the auricular systole. While the ventricle is in d., it may be said to be at rest; it comprises three-fifths of the time of an entire cardiac cycle. [Gr., diastellein, to expand.]