Coronary flow reserve
Coronary flow reserve (CFR) is the maximum increase in blood flow through the coronary arteries above the normal resting volume. Its measurement is often used in medicine to assist in the treatment of conditions affecting the coronary arteries and to determine the efficacy of treatments used.
When demand for oxygen in the myocardium is increased, the vascular resistance of the coronary arteries has the ability to reduce, and this can increase the volume of blood passing through the blood vessels. This reduction occurs because the arteries dilate, which causes an increase in the diameter of the lumen. The greatest potential for this change is normally in the branches (arterioles) of the coronary artery that penetrate the myocardium, rather than those on the surface of the heart. 
Coronary flow reserve can be measured through a variety of methods, including digital subtraction cineangiography with coronary catheterization, doppler echocardiography, and positron emission tomography (PET).
Coronary flow reserve is used in diagnostics and treatment of patients suffering from conditions such as coronary artery disease and syndrome X. In the treatment of these conditions, vasodilators are used to allow sufficient blood to flow past a stenosis, for example, and the measurement of CFR enables the efficacy of such interventions to be measured.  In patients suffering from Anderson-Fabry disease, there is evidence to suggest that CFR can be reduced. When coronary flow reserve is used in medicine, it is often expressed with a numerical value, which is formed by dividing the maximal coronary blood flow by resting blood flow. This allows for an objective view, which can aid diagnosis and treatment.
- Radó, Julia; Forster, Tamás (2001). "The significance of coronary flow reserve in chest pain syndromes" (PDF). Echo in Context. Archived from the original (PDF) on 2012-06-11.
- Klabunde, Richard E. (28 March 2014). "Critical Stenosis". Cardiovascular Physiology Concepts. Archived from the original on 2014-06-30.
- Holdright, DR; Lindsay, DC; Clarke, D; Fox, K; et al. (1993). "Coronary flow reserve in patients with chest pain and normal coronary arteries". British Heart Journal. 70: 513–9. PMC . PMID 8280515. doi:10.1136/hrt.70.6.513.
- Serruys, PW; Zijlstra, F; Laarman, GJ; Reiber, HH; et al. (August 1989). "A comparison of two methods to measure coronary flow reserve in the setting of coronary angioplasty: Intracoronary blood flow velocity measurements with a Doppler catheter, and digital subtraction cineangiography". European Heart Journal. 10 (8): 725–36. PMID 2529120.
- Dimitrow, PP; Krzanowski, M; Undas, A (2005). "Reduced coronary flow reserve in Anderson-Fabry disease measured by transthoracic Doppler echocardiography". Cardiovascular Ultrasound. 3: 11. PMC . PMID 15857518. doi:10.1186/1476-7120-3-11.
- Galderisi, M; D'Errico, A (2008). "Beta-blockers and coronary flow reserve: The importance of a vasodilatory action". Drugs. 68 (5): 579–90. PMID 18370439. doi:10.2165/00003495-200868050-00002.
- Zehetgruber, M; Mundigler, G; Christ, G; Mörtl, D; Probst, P; Baumgartner, H; Maurer, G; Siostrzonek, P (1995). "Estimation of coronary flow reserve by transesophageal coronary sinus Doppler measurements in patients with syndrome X and patients with significant left coronary artery disease". Journal of the American College of Cardiology. 25 (5): 1039–45. PMID 7897114. doi:10.1016/0735-1097(94)00544-Z.
- Hess, OM; McGillem, MJ; DeBoe, SF; Pinto, IM; et al. (1990). "Determination of coronary flow reserve by parametric imaging" (PDF). Circulation. 82 (4): 1438–48. PMID 2144799. doi:10.1161/01.CIR.82.4.1438.