The ratio of the diastolic period to heart period (diastolic
period plus systolic period), the diastolic time fraction (DTF) is
measure of cardiac oxygen supply. The ratio of diastolic and systolic
areas (mmHg s) under the reconstructed aortic pressure curve (Adia/
Asys) is a measure of supply–demand ratio. Heart rate (60/heart
period) times maximal systolic pressure Psys gives rate pressure
product (RPP) which is a measure of cardiac oxygen demand