Appeal No. 2000-0908
Application No. 08/763,728
velocity “jet” flow of blood can cause atheromatous material
and/or adherent thrombi from the walls of the aorta to
dislodge, causing embolisms. Cosgrove’s solution to this
problem involves the provision of a cap 30 at the distal end
of the cannula to substantially block the axial flow of blood
and redirect it in a more radial direction (column 3, lines
41-48). Particularly preferred by Cosgrove is the provision
of a land 42 at the distal end 40 of the cannula. The
following quote from column 4, line 66 through column 5, line
16, of Cosgrove’s specification illustrates the perceived
advantages of diverting the flow of blood to a more radial and
less axial direction:
The blood flow encounters the rounded, blunt
distal end 40 of the lumen which redirects the flow
axially in the proximal direction. When the axial
distal flow encounters the rebounding proximal flow,
the bulk of the distal flow is diverted radially
outwardly through the outlet openings in a sheet-
like cone. Thus, rather than a jetting, axial flow
experienced with conventional aortic cannula, the
cannula 20 and 20’ provide a diffused flow that more
quickly establishes a stable, more uniform velocity
blood flow in the aorta. The flow properties of the
blood are such that the cannula creates an
“umbrella” flow pattern, as shown in FIGS. 8 and 9,
that more quickly establishes a uniform flow in the
aorta.
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