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Fractional flow reserve is defined as the pressure after (distal to) a stenosis relative to the pressure before the stenosis. [2] The result is an absolute number; an FFR of 0.80 means that a given stenosis causes a 20% drop in blood pressure. In other words, FFR expresses the maximal flow down a vessel in the presence of a stenosis compared to ...
Coronary flow reserve is used in diagnostics and treatment of patients with conditions such as coronary artery disease and syndrome X. [7] 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.
The instantaneous wave-free ratio (iFR, sometimes referred to as the instant wave-free ratio or instant flow reserve) is a diagnostic tool used to assess whether a stenosis is causing a limitation of blood flow in coronary arteries with subsequent ischemia. iFR is performed during cardiac catheterisation (angiography) using invasive coronary pressure wires which are placed in the coronary ...
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Figure 1. The pressure and velocity measured in the ascending aorta in an elderly man. Wave intensity analysis [1] provides a method to calculate the properties of arterial waves that give rise to arterial blood pressure, based on measurements of pressure, P, and velocity, U, waveforms (Figure 1).
Fractional flow reserve (FFR): Testing the blood flow through a stenosis of a coronary artery to determine the perfusion of the heart. Intravascular ultrasound (IVUS): Ultrasonography of a coronary artery. Optical coherence tomography (OCT): Testing through the use of optical scattering for coronary artery disease.
Such loops can be generated by real-time measurement of pressure and volume within the left ventricle. Several physiologically relevant hemodynamic parameters such as stroke volume, cardiac output, ejection fraction, myocardial contractility, etc. can be determined from these loops.
Lung volumes. Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. [1] At FRC, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm or other respiratory muscles.