Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates generally to a surgical electrical
applicator, and more particularly, pertains to an endocardial pacing lead.
The transvenous endocardial approach is generally accepted as the
preferred technique for long term cardiac pacing. This approach is not without
complications in that the most significant fa.t is electrode displacement re-
sulting in intermittent or complete loss of pacing and/or sensing. Electrode
displacement or dislodgement is extremely prevalent ranging from 4.1% to 30%.
The present invention overcomes the difficulties of the prior art by
providing a positive fixation endocardial pacing lead.
The general purpose of this invention is to provide a new positive
fixation endocardial pacing lead using an extendable retractable helix com-
bined with a highly flexible pacing lead including a strain relief member at
the junction of the electrode and the conductor of the endocardial pacing lead.
According to one broad aspect of the invention there is provided an
endocardial pacing lead comprising a lead, a connector terminal at one end oE
; said lead, and electrode means at the other end of said lead including helical
coil fixation means rotatably mounted within said electrode means whereby said
helical fixation means rotates thereby securing said electrode means to endo-
cardial tissue, said fixation means comprising a closed end helical coil in-
cluding a sharp point and a sliding member affixed to said closed end oE said
- helical coil and including a rectangular hole in which a stylet wire may be
- inserted for rotating said helical coil, said electrode including a guide seal
having a helical lumen extending partially therethrough whereby said helical
coil rotates through said hole and through the remainder of said guide seal.
According to another broad aspect of the invention there is provided
an endocardial pacing lead comprising a lead, a connector at one end of said
lead, an electrode assembly at the other end of said lead including an electrode
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tip, a sleeve located within a rear end of said electrode tip. said lead
crimped between said sleeve and said electrode tip, strain relief coil insert-
ed over said lead, extending into, between and over said lead and said sleeve,
~; a molded tapered sliding member including a rectangular ftmnelled hole in a
rear end and supporting a closed end of a llelical coil at the other end, an
open end of said helical coil including a sharp tip, the closed end helical
coil and molded tapered sliding member axially mounted within the other end of
the electrode tip, a guide seal including a helical coil lumen extending part-
ially therethrough and supporting said sharp tipped portion of said helical
coil, and a silicone covering extending between said tip electrode to beyond
said strain relief coil and over said lead whereby a stylet having a rectangu-
lar end is inserted into the molded plastic sliding member and rotated to
actually rotate the helical coil out through the closed membrane of the guide
;` seal thereby afEixing said helical coil to myocardial tissue.According to one embodiment of the present invention, there is pro-
vided an endocardial pacing lead including an electrode assembly, a conductor
affixed to the electrode assembly and ha~ing a connector on the other end, the
electrode assembly including an extendable retractable heli~ rotatably mounted
within the electrode whereby a stylet wire is inserted down through the connect-or and pacing lead which engages within the helical assembly thereby rotating
the helix assembly and anchoring the electrode to heart tissue.
A significant aspect and feature of the present invention is an endo-
cardial pacing lead having positive fixation for permanent unipolar ventricular
pacing. An active tissue penetrating fixation member in the form of a platinum-
iridium helix coil is extended into the myocardium and retracted inside the body- - of the electrode assembly by rotating a wedge tipped stylet wire. A platinum-
iridium endocardial ring-shaped electrode surrounds the fixation helix. In a
retracted state, the helix is completely contained within the clistal end portion
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of the electrode assembly of the pacing lead. In a fully extended state, the
open end helix coil extends two turns outward beyond the electrode. The helix
is used exclusively for lead fixation and is electrically iso]ated from the
ring-shaped electrode.
Another significant aspect and feature of the present invention is
that the open end helix coil threads into a helical lumen within a silicone
rubber guide seal plug located within the distal tip of the electrode assembly
of the lead and is covered by a thin silicone rubber membrane which helps
prevent blood and tissue from entering the body of the lead while the helix
is either retracted or extended.
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A urther signiicant aspect and feature of the present invention
is that a standard stainless skeel blunt tip stylet wire is utilized or
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initial positioning of the lead in the right ventricle and a special stain-
less steel stylet wire with a plastic knob at its proximal end and a wedge
- tip at its distal end serve~ as a long 1exible screwdriver which engages
a rectangular slot o a plastiG sliding member permanently attached to the
helix for rotation of the stylet wire which extends or retracts the helix.
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Other objects and many of the attendant advantages of this in-
vention will be readily appreciated as the same becomes better understood
by reference to the following detailed description when considered in con-
nection with the acco~panying d~awings, ln which like reference numerals
designate like parts throughout the FIGURES thereof and wherein:
Figure 1 is a plan view of an endocardial pacing lead;
Figure 2 is a cross-sectional view taken along lines 2-2 of
Pigure 1 with a hellcal coil fully retracted, and;
Figure 3 is a cross-sectional exploded view of tlhe electrode
assembly with the helical coil extending out through a guide seal.
Figure l, which illustrates a plan view of an en,locardial pacing
lead 10, the present invention, shows an electrode assembly 12 on a distal
end portion of a lead 1~, a connector 16 on a proximal end portion of the
lead 14 and having a connector terminal 18 affixed therein, and a s~ylet
20 inserted through the endocardial pacing lead 10.
Figure 2~ which illustrates a cross-sectional view taken along
line 2-2 of Figure 1, shows the electrode assembly 12 as now described in
detail. The electrode assembly 12 includes a round cylindrical electrode
tip member 22 including a taper 22a to a diameter 22b, and a configured
front end 22c including a clrcumferential groove 22d and a rounded swaged
tip 22e. The internal diameter 22 accepts a ring 36a of a silicone guide
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seal 36 as later described in detail, a second internal diameter 22g
accommodates a molded tapered sllding member 32 as later described in
detail, a third internal diameter 22h accepts a stylet wire 20a of the
stylet 20, a fourth internal diameter 22i accepts the space wound trifilar
conductor coil 26 and a fifth internal diameter 22j accepts a single filar
strain relief coil 30 as later described in detail. A sleeve 24 having an
outwardly extendlng flange 24a engages within the internal diameter 22i
of the electrode 22. The 1ange 24a abuts the forward end of the intern-
al diameter 22i. The inner diameter 24b of the sleeve accepts the stylet
wire 20a and the outer diameter 24c is o sufficient diameter providing
for clearance for one end of the trifilar space wound coil 26 bet~een an
outer diameter 24c and the inner diameter 22i. The coil 26 is retained
within the electrode tip 22 along with the sleeve 24 by mechanical crimping
at locations 28a and 28b as illustrated in the figure and opposing per-
pendicular crimps as not illustrated in the figur0 for purposes of clarity
in the illustration. A single filar coil 30 acting as a strain relief coil
30 slides and engages o~er the coil 26 along the inner diameter 22j as
illustrated in the Figure. The strain relief coil 30 extends from within
the rearward portion of the electrode at 22j beyond and outwardly past
the rear of the rearward end of the electrode 22. A molded tapered sliding
member 32 including a helical coil 34 axially rotates and mounts within
the electrode tip 22. The molded tapered sliding member 32 includes a
rearward tapered portion 32a, a rounded cone-shaped funnel portion 32b,
and an interior rectangular hole 32c accepting a wedge shaped tip 20b of
the stylet wire 20. The closed end helical coil 34 includes a closed end
34a engaged in a base 32d at the closed end of the molded tapered helix
- and a sharp pointed edge 34b at the open end o the helical coil 34. The
open end of the helical coil 34 fits into a helical lumen 36b of ~he guide
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seal 36 made of silicone rubber or other like material by way o example
and for purposes of Lllu~tration only. An initial portion of the open end
of the helical coil extends throughout the substantial majority o the
longitudinal length of the guide seal 36 to a point where a closed me~brane
36c of like material extends across the ront o the guide seal 36. Outward
extending rectangular circumferential ring 36a o the guide seal 36 engages
into the inner diameter 22 o the electrode tip 22 firmly engaging the guide
seal 36 within the interior of the electrode tip 22. The orward end of
the electrode 22k is swaged -over the electrode guide seal 36 after the
electrode guide seal 36 Ccontaining closed end helical coil 34) and molded
tapered sliding member 32 are inserted within the electrode tip 22 orming
the rounded swaged tip 22e. ~ outer urethane covering 38 covers ~he elec-
trode tip 22J and extends from the coil 26 at the rearward end 221 of the
electrode tip 22 to the circumferential groove 22d of the electrode tip 22.
Preferred Mode of Ope~ation
; Figure 3, which illustrates one preerred mode of operation of
the endocardial pacing lead 10, shows the wedge tip stylet wire 20b extending
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into and engaged within the wodgc ~hape~hole 32c of the molded tapsred
sliding member 32. As the stylet knob 20c ~Pigure 1) is tu~ned, subsequent
; 20 clockwise rotatlon results in the rotation o the molded tapered sliding mem-
; ber 32~ the closed end helical coil 34 within the guide seal 36 resulting in
the sharp tip 34b penetrating through the ormerly closed top membrane 36c
of Figure 2 of silicone rubber guide seal 36 and subsequently afixing to
heart tissue in a corkscrew-like operation. The edges 36d o the membrane
36c curl up and over the edge o the helical coil 32 providing a seal between
the electrode assembly 12 and the heart tissue. Once two turns of the stylet
20a have been reached affixing the sharp pointed edge 34b of the open end of
the helical coil 34 into the heart tissue which can be confirmed through
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fluoroscopy or other like operat~on, the stylet 2Q is withdrawni
~ With the fixation closed end hellcal coil 34 ully ret~acted
using a standard blunt tip stylet wire ths electrode tip 22 can be positioned
. in the right ventricular apex with the aid of fluoroscopy. The blunt tip
Stylet wire is then removed and a plastic stylet manipulatiorl tool connects
~; to the proximal end of the lead 10 following which the wedge-shaped
. stylet 20 is introduced. Once satisfactory electrode position has been
.~ confirmed by electrical instrUmentatiOn~ slight forward pressure is main-
tained by either holding the lead 10 in this position or by irmly securing
the lead 10 at the venotomy site using a llgature tourniquet.
To achieve positive fixation by extending the helical coil 34
beyond the electrode tip 22, the wedge tipped stylet knob 20 is rotated
clockwise within the stylet manipulatio~ tool under fluoroscopic monitoring
until two turns of the helical coil ~4 àrè clearly visible beyond the distal
tip of the electrode tip 22. The knob is rotated in complete 360 in-
crements with no more than six revolutions of the stylet knob being required.
Electrode 22 fixatlon is then verlfied by turning the stylet wire 20 another
- one to one and one-half revolutlons fèeling for increased resistance to
rotation, then gently pulling back on the leaLd under f.luoroscopic monitoring
and feeling or a slight resistance to the pulling, and repeating the
electrical measurements after removing the stylet wire for adequate perform-
. ance.
The strain relie coil 30 provides for bendi.ng of the pacing lead
14 at the junction of the electrode assembly 12. The coil 30 distributes
the strain between the electrode and pacing lead over t:he entirP length of
the strain relie coil 30 providing for the integrity of the electrode
. assembly 12 in the pacing lead.
; Various modiications can be made to the endocardial pacing
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:, lead without d~parting rom the appar0nt scope of the present in-
VentioD.
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