The diastolic flow-pressure gradient relation in coronary stenoses in humans
Koen M. J. Marques, MD*,*,
Hugo J. Spruijt, MSEE*,
Christa Boer, PhD ,
Nico Westerhof, PhD ,
Cees A. Visser, MD, PhD, FACC* and
Frans C. Visser, MD, PhD*
* Cardiology, VU University Medical Center, Amsterdam, The Netherlands
Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands

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Figure 1 From top to bottom: electrocardiogram, proximal coronary pressure (prox p), distal coronary pressure (dist p) and coronary flow velocity at maximal hyperemia (left), intermediate hyperemia (middle) and baseline condition (right) in a patient with an intermediate coronary stenosis. During hyperemia, higher flow velocities and higher pressure gradients are observed compared with baseline condition and intermediate hyperemia. The arrows delineate the middiastolic data, used to construct the flow velocity-pressure gradient relation.
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Figure 2 Example of the instantaneous diastolic flow velocity-pressure gradient relation in a patient with an intermediate coronary stenosis. Measurements at baseline (open circles), maximal hyperemia (open squares) and intermediate hyperemia (solid triangles) are displayed. The solid line shows the regression line, according to the formula: .
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Figure 3 Two consecutive instantaneous diastolic flow velocity-pressure gradient measurements in an intermediate coronary stenosis. The upper and lower 2 SD curve is shown for both measurements. After determining the common part of flow velocities, the common area between the 95% confidence intervals of both measurements is determined.
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Figure 4 (A) Mean regression lines (thick lines) with 1 SD (thin lines) for all instantaneous diastolic flow velocity-pressure gradient measurements in normal coronary arteries, arteries with an intermediate stenosis (dashed lines) and with a severe stenosis. (B) Mean regression lines (thick lines) with 1 SD (thin lines) for all severe stenoses before percutaneous transluminal coronary angioplasty (PTCA) and after PTCA and stenting.
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