Appeal No. 2000-2029
Application 09/012,530
[t]he cannula assembly 10, with the needle 42
extended through the opening 34 of the dilator tip 32,
is advanced to the center of the purse string suture
54. As shown in FIG. 8, the distal end 48 of the
needle 42 punctures the aorta, in the center of the
purse string suture 54, and the cannula assembly 10 is
inserted into the puncture site until the transition
stop 36 of the dilator tip 32 contacts the outer wall
of the aorta. In the preferred embodiment of the
invention, at this stage, only the distal end 48 of the
needle 42 and the generally cylindrical portion 40 of
the dilator tip 32 are situated in the aorta. By
temporarily halting further advancement of the cannula
assembly 10 in the aorta, the transition stop 36 is
able to control the insertion depth of the needle 42 in
the aorta, thereby minimizing the risk of damage to the
back wall of the aorta.
Once the cannula assembly 10 has been inserted in
the aorta, up to the transition stop 36, the needle 42
is retracted into the passage 30 of the elongate tube
24, and the guide wire 44 is extended through the
opening 34 of the dilator tip 32 and into the aorta
(FIG. 9). The guide wire 44 facilitates insertion of
the cannula 12 in the aorta. The cannula 12 and
dilator 14 are then advanced over the guide wire 44 and
into the aorta (FIG. 10).
In light of this disclosure, it appears to us that it is the
individual who is inserting the dilator tip into the blood vessel
who temporarily halts insertion of the cannula assembly when the
“transition stop” contacts the outer wall of the blood vessel,
rather than the transition stop itself that prevents further
insertion of the cannula assembly into the blood vessel. This is
particularly true, since after retraction of the needle and
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