Note: Descriptions are shown in the official language in which they were submitted.
155
INSTRUMENT FOR PERFORMING ENDARTERECTO~Y
l~his invention relates generally to endarterec-
tomy procedures, and has to clo partlcularly with the
provision of a reaming instrument adapted to perform
endarterectomy (reaming out) of blood vessels.
While the instrument disclosed and claimed
herein finds particular use during the operation known
as coronary artery bypass graft, it will be appreciated
from what follows that the instrument can find use in a
number of operational situations, not necessarily involv-
ing heart surgery.
It is an aspect of this invention to provide a
simple, easily used manual instrument by which endarterec-
tomy can be safely and effectively performed by the
surgeon.
Accordingly, this invention provides an instru-
ment for performing endarterectomy on blood vessels,
comprising:
a reaming head which includes a straight rod-like
~o shaft rounded at one end, and a rounded helical thread
encircling the shaft,
a handle portion, and
a resilient wire secured at its one end to the
other end of the shaft in coaxial fashion, and secured at
~5 its other end to the handle portion.
Two embodiments of this invention are illustrated
in the accompanying drawings, in which like numerals
denote like parts throughout the several views, and in
which:
Figure 1 is an exploded, perspective view of a
first embodiment of this invention;
Figure 2 is a view, to a smaller scale than
Figure 1, of the instrument in its closed condition; and
Figure 3 is a view, to a la~r scale, of the
reaming head of the second embodiment of this invention.
In Figure 1, an instrument 10 for performing
endarterectomy on blood vessels in seen to include a
reaming head 12, a handle portion 14, and a resilient
wire 16.
The reaming head 12 includes a straight rod-like
shaft 18 which is rounded at its forward (rightward) end,
and which has an integral helical thread 20 encircling
the shaft 18. More particularly, the helical thread 20
has an angle of about 45 with respect to the axis of the
shaft 1~, which in the embodiment shown in-Figure 1
causes the helical thread to have a pitch greater than
its own outside diameter. It will be appreciated that it
is not considered essential that the helical thread have
a pitch greater than its own outside diameter, nor is it
essential that the thread angle be at least 45 with
respect to the axis o the shaft 18. However, a certain
"pulled out" configuration of the thread is preferred
in the conscruction of the instrument described
herein.
In the embodiment shown in Figure 1, the helical
thread 20 extends only as far as the location identified
by the numeral 22, leaving the forward or rightward portion
of the shaft 18 unthreaded. This is considered to be of
advantage in a preferred form of the invention,`in that it
allows the surgeon to easily insert the reaming'head 12
into the opened blood vessel, prior to reaming. More
specifically, it is considered of advantage, in a pre~erred
~5 form of the invention, that the shaft 18 have an unthreaded
forward section at least as long as the pitch of the
helical thread 20.
Completing the overall assembly, although not
part of the instrument during an operation procedure, is
an elongated tube 24 which is internally threaded at the
leftward end 25, and is thus adapted for threaded engage-
ment with external threads 27 which are provided on the
handle portion 18 adjacent the connection between the
handle portion 14 and the wire 16. More specifically,
the handle portion 14 has a reduced diameter throat
identified by the numeral 29, the throat 29 being
situated between the threads 27 and a main barrel 30 of
the handle portion 14. Forwardly or rightwardly of the
2~5
external threads 27 is a forwardly converging conical
portion 32 endlng in a projection 33 to which the wire 16
is silver soldered or otherwise securely affixed.
The other end of the wire 16 is connected, again
by silver soldering or some equivalent secure means, in a
coaxial fashion to one end of the shaft 18 (the end
opposite the unthreaded end as seen in Figure 1).
It is considered important that the reaming head
12 be rounded at its leading end (the end of the unthreaded
portion), so as not to catch or cut the internal walls of
a blood vessel being reamed out. Likewise, it is con-
sidered important that the helical thread 20 also be
rounded, again to avoid cutting or scratching the internal
walls of the blood vessel.
Figure 2 shows the two separate parts of the
instrument of Figure 1 in "closed" engaged position. The
open-ended tube 24 is long enough to receive the entire
length of the wire 16 plus the reaming head 12, without
the latter projecting out the rightward end 35 of the
tube 24.
Figure 3 shows a reamin~ head 36 of slightly
different configuration, constituting the second reaming
head embodiment of this invention. In Figure 3, the
reaming head 36 again has an unthreaded forward portion
38, but has a greater number of convolutions in the
helical thread 40. Again, the forward end 42 of the
reaminy head 36 is rounded, as is the profile of the
thread 40 itself.
The following specific dimensions ofparticular
instruments-built and satisfactorily tested
over a large number of operations are given only by wav
of illustration, and it is not considered that the inven-
tion is limited to these or any other specific dimenions.
Firstly, in the prototypesconstructed and tested,
all of the materials were of stainless steel, including
the handle, the wire and the reaming head.
The wire size was 15 thousandths of an inch,
and the length of the reaming head was in the region of
~4-
1 centimeter. In actual fact, three different sizes of
reaming head were built and tested, all of them having
the same length of ahout 1 centlmeter, but having
different diameters. The diameter can be expressed in
terms of the pitch diameter of the helical thread,
together with the thread height (i.e. the radial dimension of
the thread from its inner diametex to its outer diameter).
The three reaming heads constructed had thread pitch
diameters of 1 millimeter, 1.5 millimeter and 2 milli-
meters respectively. The thread height in each case wasbetween 10 and 12 thousandths of an inch. It is expected
that pitch diameters of 0.5 mm, and also sizes larger than
2 mm will also find use in operational situations. For
example, pitch diameters up to 3~ millimeters, along with
a thread height between 10 and 12 thousandths of an inch,
could well be useful in operations involving particularly
larye vessels of the body.
The threads utilized in the embodiments built
and tested all had a pitch corresponding to about 10
threads per inch. The threads were all radiused or
rounded, and of course the "nose" of the shaft of the
reaming head was also rounded.
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