Hydro- and hemodynamic effects of catheterization of vessels. II. Model experiments comparing circular and annular lumen area reduction.

Experiments and a simple theoretical analysis have been performed concerning the flow through circular (stenosis) and annular (catheter piece) lumen area reduction of rigid- and elastic-walled vessels. Both steady and pulsatile flow at various volumetric flow rates were investigated. A good agreement between the experimental and the analytical results has been found. A critical annular lumen area reduction exists on a par with the well-known critical stenosis. The strongest reduction in pressure and in volumetric flow rate was caused by the catheter pieces, compared with the stenoses. The per cent reduction in pulse mean pressure and in volumetric mean velocity at pulsatile flow was equal to the per cent reduction in pressure and volumetric mean velocity at steady flow. The influence of the geometrical shape of the stenoses and the catheter pieces is further discussed.