Stenotic Coronaries

Model Studies of Flow in Stenotic Coronary Arteries

Dr. Ralph S. Budwig, Dr. Carla Egelhoff, Mr. Jonathan Foster,

Mr. Jeff Daniels, Mr. Byron Hansen

Pulsatile flow in models of stenotic coronary arteries has been examined for a physiologically realistic flow waveform and for low and high flow conditions (i.e., below and above the basal state). Flow visualization, LDV measurements, and numerical simulations have been conducted in several models to span stenosis size, symmetry, and wall roughness of medical interest. These stenotic flows are all characterized by a high speed jet of fluid encompassed by a low speed region of recirculating fluid. The jet is central for the symmetric stenoses and attached to the wall for the eccentric stenoses. The recirculating fluid zone persists over most of the cardiac cycle but changes in length as the cycle progresses. The investigation has revealed that a distinguishing feature of the flow distal to a severe stenosis is the onset of flow instability and turbulence. For high flow conditions both the symmetric and eccentric severe stenoses have a region of unstable flow over most of the cycle. The location and length of the unstable flow region changes as the cycle progresses. Thus, the onset of flow instability and turbulence may be one factor that makes a severe stenosis in the coronary arteries susceptible to thrombogenesis.

The plot shows three coronary artery waveforms. The solid line curve is the target waveform estimated from the Berne and Levy waveform (Re_mean= 82, Re_peak= 150, Cycle time = 7 seconds). The plus symbol curve is a plot of a typical low range for the experimental data (Re_mean= 63, Re_peak= 113, Cycle time = 7 seconds), and the diamond is the high range for the experimental data, (Re_mean= 154, Re_peak= 256, Cycle time = 4.2 seconds).

FLOW VISUALIZATION

CORONARY STENOSIS MODELS

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