ECHONOMY Tools for Echocardiographic Calculations Muhamed Saric, MD, PhD
New York University
FFR stands for fractional flow
reserve and is a measure of resistance in the epicardial
(conductance) coronary arteries.
Pressure wire is advanced into a coronary artery past the stenosis and
MPP is measured.
Pressure wire is then pulled back and MAP measured.
Pressure measured after induction of maximal hyperemia (with
e.g. adenosine, 140 µg/kg/min)
Pressure gauge is located 3 cm proximal from wire tip.
Pressure wire is a fiberoptic device that emits light from a
control unit and transmits it through along the fiber to the sensor.
Pressure-induced elastic movement of the sensor modulates the intensity of
reflection. The light signal is then transmitted back through the same
optic fiber and detected by a photo diode in the control unit.
Mean arterial pressure (MAP)
Mean post-stenosis pressure (MPP)
The more severe the coronary stenosis, the larger the
pressure drop between MAP and MPP. In severe stenosis, MAP : MAP > 5 : 1.
Percutaneous coronary intervention is performed if FFR < 0.75.
Lamm C, Dohnal M, Serruys
PW, Emanuelsson H. High fidelity translesional pressure gradients during
percutaneous transluminal coronary angioplasty: correlation with
quantitative coronary angiography.Am Heart J. 1993;126:66-75.[This article has a nice drawing of
the pressure wire.]
Pijls NH, De Bruyne B, Peels K, Van Der Voort PH, Bonnier HJ, Bartunek J
Koolen JJ, Koolen JJ. Measurement of fractional flow reserve to assess the
functional severity of coronary-artery stenoses.
N. Engl. J. Med.