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Figure 2 Simultaneous determination of i.c. distal occlusive velocity (Vioccl = 2.5 cm; upper panel, left side) and wedge pressure (Poccl = 10 mm Hg) together with mean aortic pressure (Pao = 94 mm Hg; right side). The i.c. flow velocity tracing during vessel patency (Viø-occl = 48 cm), i.e., after dilation of the stenosis and following cessation of hyperemia, is shown on the lower left hand side. The flow velocity tracings depict the instantaneous velocity over time (horizontal axis) in the upper, and the flow velocity trend over 90 s in the lower part of the panels. The trend of the lower panel gives also the coronary flow velocity reserve (CFVR, "ratio" = 2.1) measurement. Velocity-derived collateral flow index (CFIv) in this example is equal to 2.5/48 = 0.05. During coronary occlusion, the i.c. ECG shows ST-elevations (right side panel) which disappear after PTCA balloon deflation. APV = average peak flow velocity (cm/s, i.e. maximum flow velocity during a cardiac cycle averaged over three cardiac cycles); B = baseline flow velocity (cm/s) at rest; CFVR = coronary flow velocity reserve; Pra = right atrial or central venous pressure (CVP); P = peak flow velocity during hyperemia; PTCA = percutaneous transluminal coronary angioplasty; S = search mode for peak flow velocity.
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