fractional flow reserve (FFR) Established measures of coronary physiology. The fractional flow reserve (FFR) is an index of epicardial coronary physiology and is measured during maximal hyperemia. The coronary flow reserve (CR) is a measure of both the epicardial and microvascular physiology and is expressed as the ratio of hyperemic to basal flow, simplified to the ratio of basal to hyperemic mean transit time. The index of microcirculatory resistance (IMR) is a spe- cific index of the microcirculation and is expressed as the product of Pd and mean transit time. Pw here indicates the coronary wedge pressure. #FFR #FractionalFlowReserve #Calculation #Cardiology #Pathophysiology #CFR
