Coronary Flow Reserve (CFR)
Coronary flow reserve (CFR) measures the capacity of the coronary arteries to respond to a physiological increase in oxygen demands with an equivalent surge in blood flow. For example, during exercise, the heart often needs more oxygen so, to meet this demand, blood rushes to the organ—CFR measures how effective the coronary arteries are at completing this action. In individuals without heart conditions, CFR can be measured at a 3, which means coronary circulation can be tripled when needed. An abnormal rating of CFR is typically around 2.
How CFR Is Used in DiagnosisCFR is often used to diagnose and treat patients with coronary artery disease, especially those dealing with noticeable chest pain. It allows physicians to evaluate the function of the arteries as well as determine how well certain treatments are working.
How CFR Is PerformedDuring the procedure, the baseline coronary circulation will be recorded and then a vasodilator (medication that dilates blood vessels) will be administered intravenously for several minutes. Once the blood vessel reaches a hyperemic condition (excess blood in the blood vessel), the rate of coronary circulation will be measured. These measurements are most often recorded using a catheter-guided wire that is positioned in the blood vessel (using Doppler or thermodilution technology). It can also be recorded using positron emission tomography (PET).
What to ExpectDue to the use of a vasodilator, patients can experience some side effects after the procedure, such as a slow heartbeat, chest soreness, low blood pressure and/or shortness of breath. However, these side effects are generally rare and resolve pretty quickly after the procedure. The use of CFR in asthmatic patients may be discouraged, as persistent bronchospasms can occur.
EffectivenessThere are certain limitations to CFR, which is why other measurements should be taken into account when evaluating heart disease, such as fractional flow reserve (FFR). For example, CFR is the ratio of hyperemic and baseline blood flow. However, for a patient with tachycardia (rapid heart rate), hypertrophic cardiomyopathy or any other reason for a higher-than-average baseline, results may be skewed.
Tampa General Hospital’s Heart & Vascular Institute is home to renowned experts who provide state-of-the-art diagnostics and treatment for cardiovascular conditions. You’ll consult with some of the most experienced and skilled physicians in the field whose experience allows TGH to handle some of the most complex cases in the region.