Pressure and coronary Doppler tracings

FFR: fractional flow reserve is computed from ratio of aortic and coronary pressures; CFR: coronary flow reserve is computed from ratio of hyperemic to rest average peak velocity. Using both pressure and flow; HSR: hyperemic stenosis resistance; HMR: hyperemic myocardial resistance can also be calculated; Pa: pressure, aortic; Pd: pressure distal (guidewire).