Fractional Flow Reserve (FFR)

Fractional Flow Reserve, (often referred to as FFR) is an invasive (percutaneous) method used to measure intra coronary pressure to determine the severity of ischemia in the vessels of the heart. Coronary pressure-derived fractional flow reserve (FFR) is an invasive index of stenosis severity that is a substitute for noninvasive stress testing.

Explanation
The clinical significance of coronary-artery stenoses of moderate severity can be difficult to determine using angiography alone. Myocardial fractional flow reserve (FFR) is an index of the functional severity of coronary stenoses that is calculated from pressure measurements made during coronary arteriography.

Application
The measurement is performed on patients commonly suffering from multi vessel disease. Access to the vessels is attained via either the femoral (groin) or radial arteries (wrist) using a sheath and guidewire. A small, multi-function sensor on the tip of the wire (commonly a transducer measures pressure, temperature and flow to determine the exact severity of the lesion and aids diagnosis and treatment by measuring pressure on either side of the ischemic region, before and after treatment.



PTCA of a coronary stenosis without documented ischemia at noninvasive stress testing is often performed, but its benefit is unproven. A value of 0.75 identifies stenoses with hemodynamic significance. In patients with a coronary stenosis without evidence of ischemia, coronary pressure-derived FFR identifies those who will benefit from PTCA.





Definition


In other words, the maximum flow down a vessel in the presence of a stenosis compared to the maximum flow in the hypothetical absence of the stenosis.







Pressure measurement
To measure pressure, a pressure pull back recording is taken during a hyperemic session.