U.S. patent application number 12/396350 was filed with the patent office on 2009-07-02 for electrical conduction block implant device.
Invention is credited to Richard Cornelius, Robert S. Schwartz, William Swanson.
Application Number | 20090171431 12/396350 |
Document ID | / |
Family ID | 32965570 |
Filed Date | 2009-07-02 |
United States Patent
Application |
20090171431 |
Kind Code |
A1 |
Swanson; William ; et
al. |
July 2, 2009 |
Electrical Conduction Block Implant Device
Abstract
The present invention provides an electrical block implant sized
and shaped for securement at the perimeter of the pulmonary ostium
of the left atrium. By utilizing various expandable ring designs
and optional anchoring mechanisms, the present invention causes
even, circular scarring around the perimeter of the pulmonary
ostium, achieving reliable blocking of aberrant electrical signals
responsible for atrial fibrillation.
Inventors: |
Swanson; William; (St. Paul,
MN) ; Cornelius; Richard; (Wayzata, MN) ;
Schwartz; Robert S.; (Rochester, MN) |
Correspondence
Address: |
INSKEEP INTELLECTUAL PROPERTY GROUP, INC
2281 W. 190TH STREET, SUITE 200
TORRANCE
CA
90504
US
|
Family ID: |
32965570 |
Appl. No.: |
12/396350 |
Filed: |
March 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10792110 |
Mar 2, 2004 |
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12396350 |
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60451865 |
Mar 3, 2003 |
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60451864 |
Mar 3, 2003 |
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Current U.S.
Class: |
623/1.11 |
Current CPC
Class: |
A61B 17/320725 20130101;
A61F 2002/91525 20130101; A61F 2002/9511 20130101; A61F 2230/0054
20130101; A61F 2220/0016 20130101; A61F 2002/9665 20130101; A61F
2/91 20130101; A61F 2/915 20130101; A61F 2/848 20130101; A61F
2002/8483 20130101; A61F 2002/91533 20130101; A61F 2002/91558
20130101; A61F 2/2487 20130101 |
Class at
Publication: |
623/1.11 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1. A delivery mechanism for an electrical conduction block device
comprising: a catheter having an inner shaft and a movable sheath;
said movable sheath surrounding said inner shaft; a plurality of
expandable arms disposed at a distal end of said inner shaft; a
distal end of each expandable arm having a retention mechanism
engageable with one end of said electrical conduction block device;
and, said plurality of expandable arms being selectively expanded
or contracted according to movement of said movable sheath.
2. A delivery mechanism according to claim 1, wherein said
retention mechanism comprises a wire that connects said distal end
of each expandable arm to a portion of said electrical conduction
bock device.
3. A delivery mechanism according to claim 2, wherein said
retention mechanism comprises a strip of material that fits within
a groove of a portion of said electrical conduction block
device.
4. A delivery mechanism according to claim 3, wherein said
retention mechanism further comprises a wire for securing said
strip of material in said groove.
5. A delivery mechanism according to claim 1, wherein said
retention mechanism comprises a cradle that receives a portion of
said electrical conduction block device wherein a wire secures said
portion of said electrical conduction block device in said
cradle.
6. A delivery mechanism according to claim 1, wherein said
retention mechanism includes a plurality of wires that are
insertable into a hole of a portion of said electrical conduction
block, wherein at least one of said wires has a portion with a
larger diameter than the other of said plurality of wires.
7. A delivery mechanism for an expandable electrical conduction
block device comprising: a catheter having an inner shaft and a
movable sheath; said movable sheath surrounding said inner shaft; a
ring of pins disposed at a distal end of said inner shaft; each of
said pins being engageable with a mating portion of one end of said
electrical conduction block device; said pins and said mating
portion of one end of said electrical conduction block being
prevented from disengagement so long as said movable sheath covers
said ring of pins; and, said movable sheath being movable over said
ring of pins in one of a forward and reverse direction depending on
a deployment decision by a user.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. patent application
Ser. No. 10/792,110 filed Mar. 2, 2004 entitled Electrical
Conduction Block Implant Device which in turn claims priority to
U.S. Provisional Application Ser. No. 60/451,865 filed Mar. 3, 2003
entitled Implantable Device to Create Ostial Electrical Block in
the Pulmonary Veins for Treatment of Atrial Fibrillation and to
U.S. Provisional Application Ser. No. 60/451,864 filed Mar. 3, 2003
entitled Implantable Ring to Create Electrical Block in Pulmonary
Vein Ostium for Treating Atrial Fibrillation, the entire contents
of all of which being hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] Pumping of the human heart is caused by precisely timed
cycles of compartmental contractions of the heart muscle which lead
to an efficient movement of blood into the heart and out to the
various bodily organs. These precisely timed cycles are controlled
and directed by electrical signals that are conducted through the
cardiac tissue and can be referred to as pacing signals.
[0003] The sinoatrial node (SA node) is the heart's natural
pacemaker, located in the upper wall of the right atrium. The SA
node spontaneously contracts and generates nerve impulses that
travel throughout the heart wall causing both the left and right
atriums to sequentially contract according to a normal rhythm for
pumping of the heart. These electrical impulses continue to the
atrioventricular node (AV node) and down a group of specialized
fibers called the His-Purkinje system to the ventricles. This
electrical pathway must be exactly followed for proper functioning
of the heart.
[0004] When the normal sequence of electrical impulses changes or
is disrupted, the heart rhythm often becomes abnormal. This
condition is generally referred to as an arrhythmia and can take
the form of such arrhythmias as tachycardias (abnormally fast heart
rate), bradycardias (abnormally slow heart rate) and fibrillations
(irregular heart beats).
[0005] Of these abnormal heart rhythms, fibrillations, and
particularly atrial fibrillations, are gaining more and more
attention by clinicians and health workers. Atrial fibrillation
develops when a disturbance in the electrical signals causes the
two upper atrial chambers of the heart to quiver instead of pump
properly. When this happens, the heart is unable to discharge all
of the blood from the heart's chambers thus creating a situation
where the blood may begin to pool and even clot inside the atrium.
Such clotting can be very serious insofar as the clot can break
away from the atrial chamber and block an artery in the brain, and
thereby cause a stroke in the individual.
[0006] A variety of treatments have been developed over the years
to treat atrial fibrillation, namely, treatments to either mitigate
or eliminate electrical conduction pathways that lead to the
arrhythmia. Those treatments include medication, electrical
stimulation, surgical procedures and ablation techniques. In this
regard, typical pharmacological treatments have been previously
disclosed in U.S. Pat. No. 4,673,563 to Berne et al.; U.S. Pat. No.
4,569,801 to Molloy et al.; and also by Hindricks, et al. in
"Current Management of Arrhythmias" (1991), the contents of which
are herein incorporated by reference.
[0007] Surgical procedures, such as the "maze procedure", have also
been proposed as alternative treatment methods. The "maze"
procedure attempts to relieve atrial arrhythmia by restoring
effective atrial systole and sinus node control through a series of
incisions.
[0008] The Maze procedure is an open heart surgical procedure in
which incisions are made in both the left and right atrial walls
which surround the pulmonary vein ostia and which leave a
"maze-like" pathway between the sinoatrial node and the
atrioventricular node. The incisions are sewn back together but
result in a scar line which acts as a barrier to electrical
conduction.
[0009] Although the "maze" procedure has its advantages, in
practice it can be a complicated and a particularly risky procedure
to perform since the surgeon is making numerous physical incisions
in the heart tissue. Due in part to the risky nature of the Maze
procedure, alternative, catheter-based treatments have been
advanced. Many of these catheter devices create the desired
electrical block by way of ablation devices designed to burn
lesions into the target tissue. Examples of these devices can be
seen in U.S. patents: U.S. Pat. No. 6,254,599 to Lesh; U.S. Pat.
No. 5,617,854 to Munsif; U.S. Pat. No. 4,898,591 to Jang et al.;
U.S. Pat. No. 5,487,385 to Avitall; and U.S. Pat. No. 5,582,609 to
Swanson, all incorporated herein by reference.
[0010] Although ablation catheter procedures remain less invasive
than previous surgical methods like the "maze" procedure, they
nevertheless retain a significant element of risk. For example,
ablation procedures often utilize high power RF energy or
ultrasonic energy, which may adequately create electrical block,
but their inherent destructive nature allows for the possibility of
unintended damage to the target tissue or nearby areas.
[0011] Further, it is often difficult to achieve certainty as to
whether the appropriate amount of ablation has been performed
uniformly around the perimeter of the target site or if the desired
site is even being ablated.
[0012] Ablation procedures have also seen an occurrence of stenosis
in the pulmonary veins as a response to the ablation. This is a
serious complication and as a result, many doctors try to limit
their treatment to the ostium of the pulmonary veins to minimize
the risk of creating a stenosis in the pulmonary veins.
[0013] Finally, various implant devices have also been proposed.
Examples of such proposed devices are disclosed in co-pending U.S.
application Ser. No. 10/192,402 filed Jul. 8, 2002 entitled
Anti-Arrhythmia Devices and Methods of Use, the entire contents of
which is hereby incorporated by reference.
[0014] The solutions in the prior art, however, are not believed to
be entirely effective in many cases, and indeed may result in
actually inducing long term arrhythmias and inefficacy.
[0015] As a result, what is needed are minimally invasive
techniques for creating electrical block in the pulmonary veins
which reduce the complication risk of previously known procedures,
while increasing effectiveness and speed of the procedure to create
electrical block.
OBJECTS AND SUMMARY OF THE INVENTION
[0016] It is an object of the present invention to provide a
minimally invasive device and technique for deploying such a device
that safely and effectively blocks aberrant electrical signals at
or near the ostium of the pulmonary veins.
[0017] It is a further object of the present invention to provide a
minimally invasive electrical block device that is easy to deploy
and has a low risk of complication.
[0018] It is yet a further object of the present invention to
provide an electrical block device that consistently creates a
circumferential scar line around the pulmonary ostium to completely
block aberrant electrical signals causing atrial fibrillation.
[0019] The present invention achieves these objects by providing an
electrical block implant sized and shaped for securement at the
perimeter of the pulmonary ostium of the left atrium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1A-1C illustrate three example variations of pulmonary
ostia;
[0021] FIG. 2 illustrates a flattened sectional view of an
expandable ring according to the present invention;
[0022] FIG. 3 illustrates a side view of an electrical block device
according to the present invention;
[0023] FIG. 4 illustrates the electrical block device of FIG. 3 at
a pulmonary vein bifurcation;
[0024] FIG. 5 illustrates the electrical block device of FIG. 3 in
an expanded position;
[0025] FIG. 6 illustrates the electrical block device of FIG. 3 in
a fully deployed position;
[0026] FIG. 7 illustrates the electrical block device of FIG. 3 in
a fully deployed position;
[0027] FIG. 8 illustrates a side view of an electrical block device
according to the present invention;
[0028] FIG. 9 illustrates a side view of an electrical block device
according to the present invention;
[0029] FIG. 10 illustrates a side view of an electrical block
device according to the present invention;
[0030] FIG. 11 illustrates a side view of an electrical block
device according to the present invention;
[0031] FIG. 11A illustrates a side view of an electrical block
device according to the present invention;
[0032] FIG. 12 illustrates a side view of an electrical block
device according to the present invention;
[0033] FIG. 13 illustrates a side view of an electrical block
device according to the present invention;
[0034] FIG. 14 illustrates a side view of an expandable ring
according to the present invention;
[0035] FIG. 15 illustrates a partial close up side view of an
expandable ring according to the present invention;
[0036] FIG. 16 illustrates a flattened sectional view of the
expandable ring of FIG. 14;
[0037] FIGS. 17A and 17B illustrate cross-sectional views of a
conduction block device of the present invention in its implanted
state;
[0038] FIG. 18 illustrates another embodiment of the expandable
ring design according to the present invention;
[0039] FIG. 19 illustrates another embodiment of the expandable
ring design according to the present invention;
[0040] FIG. 20 illustrates a side view of an electrical block
device according to the present invention;
[0041] FIG. 21 illustrates a flattened sectional view of a primary
expandable ring of FIG. 20;
[0042] FIG. 22 illustrates a top view of a secondary pressure ring
according to the present invention;
[0043] FIG. 23 illustrates a top view of a secondary pressure ring
according to the present invention
[0044] FIG. 24 illustrates a side view of an expandable ring
according to the present invention;
[0045] FIG. 24A illustrates a flattened sectional view of the
expandable ring of FIG. 24;
[0046] FIG. 25 illustrates a side sectional view of an expandable
ring according to the present invention;
[0047] FIG. 26 illustrates a side sectional view of an expandable
ring according to the present invention;
[0048] FIG. 27 illustrates a flattened sectional view of the
expandable ring of FIG. 26;
[0049] FIGS. 28A-28C illustrate a preferred embodiment of a
delivery system in accordance with the present invention;
[0050] FIGS. 29A-29C illustrate another preferred embodiment of a
delivery system in accordance with the present invention;
[0051] FIG. 30 illustrates another preferred embodiment of a
delivery system in accordance with the present invention;
[0052] FIG. 31 illustrates another preferred embodiment of a
delivery system in accordance with the present invention;
[0053] FIG. 32 illustrates another preferred embodiment of a
delivery system in accordance with the present invention;
[0054] FIG. 33 illustrates another preferred embodiment of a
delivery system in accordance with the present invention;
[0055] FIG. 34 illustrates a side view of an expandable ring
according to the present invention;
[0056] FIG. 35 illustrates a side view of an expandable ring
according to the present invention;
[0057] FIG. 36 illustrates a side view of a deployment apparatus
according to the present invention;
[0058] FIG. 37 illustrates a side perspective view of an electrical
block device according to the present invention;
[0059] FIG. 38 illustrates a side view of the electrical block
device of FIG. 35;
[0060] FIG. 39 illustrates a magnified perspective view of the
expandable ring of FIG. 35;
[0061] FIG. 40 illustrates a side view of the electrical block
device of FIG. 35 in a loaded state;
[0062] FIG. 41 illustrates a side perspective view of the
electrical block device of FIG. 35;
[0063] FIG. 42 illustrates a top view of the expandable ring of
FIG. 35 in an expanded state;
[0064] FIG. 43 illustrates a top view of the expandable ring of
FIG. 42 in a cinched state;
[0065] FIG. 44 illustrates a side perspective view of the
electrical block device of FIG. 35; and,
[0066] FIG. 45 illustrates a top view of the electrical block
device of FIG. 35.
DETAILED DESCRIPTION OF THE INVENTION
[0067] The ostium of the pulmonary veins has a highly variable
geometry from one patient to another and this presents difficulty
in reliably treating atrial arrhythmias using previous methods.
That is, the variable geometry has in the past made it difficult to
reliably create a continuous line of electrical block around the
perimeter of the ostium in each and every patient.
[0068] In illustration of this point, FIGS. 1A-1C present three
ostium geometries that can occur in the general human population.
These Figures show a left atrium 10 of a human heart wherein two
adjacent pulmonary veins 11 may originate directly from two ostia
in the left atrium (FIG. 1B) or may originate from one ostia in the
left atrium followed by a bifurcation 13 downstream of the left
atrium. Moreover, the bifurcation 13 may be located near the left
atrium (FIG. 1A) or far from the left atrium (FIG. 1C). Finally,
various hybrids of these geometries are also possible as some
people can have more or less than the typical two pulmonary veins
originating on each of the right and left sides of the left atrium
10.
[0069] In addition to these geometric variations, the ostia may
differ in diameter and location of the side branches from patient
to patient. For example, typical target site diameters may range
anywhere from about 10 to 30 mm. This provides a considerable
challenge for any consistently performed electrical block procedure
for the treatment of an atrial arrhythmia.
[0070] To address this problem, the present invention provides an
electrical block device that is implantable and anchorable within
the pulmonary veins and/or left atrium of many different
geometries. That is, the present invention presents a device and
method that is adaptable for use in conducting substantially
uniform treatment of a wide segment of the human population.
[0071] And generally speaking, the present invention performs this
function in a way that consistently circumferentially blocks
aberrant electrical signals through its presence in the ostium of
the pulmonary veins. The electrical block device in accordance with
the present invention may act through the mere presence in the
ostium and/or through controlled scarring caused by the device.
[0072] The controlled scarring can be created by a number of
possible mechanisms. One possible mechanism is to have the device
press against the tissue with enough force to cause pressure
necrosis. As the tissue necroses, the device slowly migrates
through the wall and scar tissue forms behind the device as it
slowly migrates through the tissue wall. With this mechanism, it is
possible that the device can ultimately migrate through the entire
tissue wall leaving a line of scar through the entire wall
thickness.
[0073] In another possible mechanism, the device can press against
the tissue causing tension in the tissue wall. This tension in the
tissue can cause fibrosis in the wall without having the device
actually pass through the wall as was described for the pressure
necrosis mechanism above.
[0074] Another possible mechanism is to have the presence of the
device cause necrosis in the tissue as a result of a reaction to
the material of the device or a material attached to the device. It
is also possible to use combinations of these mechanisms.
[0075] The controlled scarring is believed to disrupt the cellular
structure of cardiac tissue that is present in or on the pulmonary
vein wall or the atrial wall outside the ostia and thereby prevent
such cardiac tissue from propagating aberrant electrical signals
that cause the atrial arrhythmias. While this invention describes
use for electrical isolation of pulmonary veins, these same devices
and methods can also be applied to other sites such as the superior
vena cava or the coronary sinus.
[0076] Electrical Block Device with Anchoring Clip
[0077] A first preferred embodiment of the present invention is
depicted in FIGS. 2-7 and comprises an electrical block device 100
that has three main functional components: an expandable ring 102,
and an anchoring clip 106 and a clip loop 104 that connects the
ring 102 with the clip 106.
[0078] With reference to FIGS. 6 and 7, it can be seen that in the
fully deployed condition of the device 100 in an ostium 118 of a
bifurcated pulmonary vein of the heart, the expandable ring 102
expands against the ostial tissue and the anchoring clip 106 abuts
against the bifurcation 116 of the pulmonary veins 114. It can also
be seen that the anchoring clip 106 is connected to the expandable
ring 102 by the clip loop 104 that arcs over the diameter of the
expandable ring 102.
[0079] The expandable ring 102 expands from its undeployed
configuration by as much as 10 times or more beyond its size in a
compressed state so as to press around the perimeter of the ostium.
This expansile force assists in securing the expandable ring 102 in
proper position.
[0080] In addition to its function of spatially positioning the
device 100 in the ostial space, the expandable ring 102 also serves
as the primary mechanism of creating the desired electrical
conduction block. The expandable ring 102 can cause this electrical
block either by inducing controlled scarring of the tissue
contacted by the ring 102 or by the mere presence of the ring
itself, or by a combination of the two. And as to the use of
controlled scarring, any controlled method of scarring may be used,
such as chemical coatings on the ring 102 that cause scarring,
physical scarring devices mounted on the ring 102, or even mere
physical expanding pressure from the ring 102 against the
tissue.
[0081] Referring to FIG. 2, the electrical block device 100 is
shown in a cut and flattened sheet configuration for illustrative
purposes. As is evident, the expandable ring 102 is structured from
a continuous and regularly angled wire that forms an overall
wave-like or sinusoidal shape. Two ends of the clip loop 104 extend
from the expandable ring 102 portion of the device 100 and
terminate in the wire structure that forms the anchoring clip
106.
[0082] Preferably, the wire that forms the electrical block device
100 is composed of nitinol or a similar elastic metal and is formed
by heat setting to a fully expanded shape. Typically, this heat
setting can be performed in an oven or salt bath, and yields a ring
that is larger in its formed diameter than the target ostium
diameter. As a result, the ring 102 exerts an outward force against
the ostial wall when deployed, holding the device 100 in contact
with the tissue.
[0083] The force exerted by the expandable ring 102 can be adjusted
to a desired level by varying the thickness or width of the ring
102. The diameter/expansion ratio of the expandable ring 102 can
also be varied to yield a different profile of force applied to the
tissue upon expansion of the ring. Generally, increased expansion
pressure better secures the expandable ring 102 in place and may
further create more prominent scarring at the target area.
[0084] In one preferred embodiment, the ring can be cut from a
Nitinol tube having a diameter of about 0.150 inches and a wall
thickness of about 0.015 inches. The struts of the ring can be cut
about 0.015 inches wide and with a length between turnarounds of
about 0.3 inches. For a target ostia having an internal diameter of
16 mm, this ring could be cut with six cells (i.e., it could have
six turnarounds on both the top and the bottom). For this 16 mm
target site, the ring could be formed to a diameter of about 20 mm.
It should be noted that these dimensions are merely exemplary and
that these dimensions can vary.
[0085] As discussed above, the clip loop 104 arcs over the diameter
of the expandable ring 102 when the device is deployed. As a
result, as shown in FIGS. 6 and 7, the clip loop 104 serves to
position the anchoring clip 106 at an appropriate distance from the
expandable ring 102, and urge the anchoring clip 106 against the
bifurcation 116 between the branches of the pulmonary vein. The
curved design of clip loop 104 provides for some flexibility and
"springiness" between the anchoring clip 106 and the expandable
ring 102.
[0086] Referring to FIGS. 2 and 5, the anchoring clip 106 of the
present preferred embodiment provides two closely spaced loops 103,
having a single barb 105 within each of the loops 103. When a small
portion of tissue of the bifurcation 116 moves between the two
loops 103, the barbs 105 penetrate into the tissue and thereby
retain the tissue between the two loops 103. Any type of clip or
anchoring design may be used in place of the present anchoring clip
106 design, so long as the anchoring device can provide securing
force from the expandable ring 102 to the tissue.
[0087] With regard to delivery of the electrical block device 100
to the target site, the electrical block device 100 is first
compressed into an undeployed state and is placed within a
deployment sheath 108, as seen in FIG. 3. Within the deployment
sheath 108 is a guiding catheter 112, used for positioning and
deploying the electrical block device 100. The electrical block
device 100 sits over the guiding catheter 112 such that the clip
loop 104 is positioned between two guide wires 110 that extend out
from the distal tip of the guiding catheter 112.
[0088] The guidewires 110 are conventional steerable guidewires
having diameters typically in the range of 0.014 inches to 0.038
inches and must be steered down the two lumens past the
bifurcation. Initially, the sheath 108 encapsulates the entire
electrical block device 100 against the guiding catheter 112.
However, as will be evident from the description below, this
positioning configuration allows the electric block device 100 to
easily slide off of the guiding catheter 112.
[0089] Referring to FIGS. 3 and 4, the loaded sheath 108 is
advanced into the atrium, where the sheath is then partially
retracted (or the guide catheter 112 is advanced out of the sheath
108) SO that the clip loop 104 protrudes beyond the deployment
sheath 108, thereby allowing the guide wires 110 to be more easily
manipulated and positioned.
[0090] As the deployment sheath 108, guiding catheter 112, and
electrical block device 100 are urged towards the pulmonary vein
ostia, each guide wire 110 travels down a different pulmonary vein,
centering the anchoring clip 106 on the bifurcation 116 of the
pulmonary veins. The closer the guiding catheter 112 comes to the
bifurcation 116, the more precisely aligned the anchoring clip 106
becomes with the bifurcation 116 until the anchoring clip 106
touches and finally "clips" onto the tissue of the bifurcation 116
via the barbs 105 located on the loops 103 of the clip 106.
[0091] The deployment process continues by simply sliding the
deployment sheath 108 back past the expandable ring 102 as is best
seen in FIG. 5. Without the containment of the deployment sheath
108, the expandable ring 102 increases in diameter to its formed
size, pressing on the target tissue.
[0092] With the electrical block device 100 secured, the guiding
catheter 112 and deployment sheath 108 are backed out of the atrium
and removed from the body, leaving the device 100 in its target
location as seen in FIGS. 6 and 7.
[0093] Due to the variation in geometry of pulmonary ostia, a
pre-operation procedure such as MRI may be helpful to determine the
geometry and approximate diameter of the target ostium. With this
information, the electrical block device 100 may be better adjusted
to suit the patient's target ostium by adjusting aspects such as
the expanded diameter of the expandable ring 102, the length of the
clip loop 104, or the size of anchoring clip 106.
[0094] Electrical Block Device with Anchoring Barbs
[0095] The previously described preferred embodiment positioned and
secured the anchoring clip 106 before securing the expandable ring
102. However, the reverse order is also possible according to a
preferred embodiment shown in FIG. 8.
[0096] The preferred embodiment as shown FIG. 8 is generally
similar to the previous embodiment, with perhaps two main
exceptions. In the embodiment as shown in FIG. 8, the first primary
difference is the use of positioning barbs 220 with the expandable
ring 220 and the second primary difference is the use of a clip
loop 204 that is elastic.
[0097] The barbs 220 are located around the perimeter of expandable
ring 202, providing additional anchoring support when the
expandable ring 202 is in the fully expanded position. The elastic
clip loop 204 secures on either side of the expandable ring 202, in
the same manner as the previous embodiments. However, a portion of
each side of the elastic clip loop 204 has a multi-angled,
wave-like elastic section 205. This elastic section 205 allows for
a degree of variation in the distance between the position of the
deployed expandable ring 202 and the bifurcation 216.
[0098] In operation, the electrical block device 200 with anchoring
barbs 200 is loaded and deployed in a manner similar to the
previously described embodiment. The expandable ring 202 is loaded
within a deployment sheath 208 and around a guiding catheter, with
the elastic clip loop 204 to sit between guide wires 210.
[0099] The electrical block device 200 is positioned near the
desired target tissue of the ostia and the guide wires 210 are
inserted into each pulmonary vein 214. When a desired target
location has been achieved, the deployment sheath 208 is withdrawn
so as to expose the expandable ring 202. The expandable ring 202
now being unconstrained, it expands and presses against the target
tissue, pushing barbs 220 into the perimeter of the ostium 218.
[0100] Finally, the anchoring clip 206 is secured to the
bifurcation 216 using guiding catheter 212 to apply pressure on the
elastic clip loop 204 towards the bifurcation 216. This elastic
section 205 enables the elastic clip loop 204 to stretch in
response to the pressure and thus allows the anchoring clip 206 to
secure to the bifurcation 216. At that point, the guiding catheter
212 and deployment sheath 208 may be removed from the patient.
[0101] In this manner, the electrical block device with anchoring
barbs 200 provides the additional anchoring of barbs 220 while
allowing for an alternative method of deployment. It should be
understood that although this preferred embodiment allows the
anchoring clip 206 to be clipped to the bifurcation 216 after
expansion of the expandable ring 202, this order is not the only
method of deployment. The electrical block device with anchoring
barbs 200 may also be deployed in a similar fashion as electrical
block device 100 of the first embodiment, as described above, where
the anchoring clip 206 is clipped to the bifurcation 216 first,
followed by deployment of the expandable ring 202.
[0102] Electrical Block Device without Sheath
[0103] FIG. 9 illustrates yet another preferred embodiment of the
present invention. In this embodiment, the overall design of the
electrical block device 300 is similar to the previously described
embodiments; however, instead of utilizing a deployment sheath, a
deployment wire 322 is used.
[0104] More specifically, as in previous embodiments, the
electrical block device 300 is loaded on a guiding catheter 312 for
desired positioning near the perimeter of the ostium. A clip loop
304 is positioned between two guide wires 310 at the tip of guiding
catheter 312.
[0105] The main distinction of this design lies in the expandable
ring 302, which, unlike previous embodiments, has a series of holes
320 integrated into the expandable ring 302 structure. As seen in
FIG. 9, a thin wire 322 passes through these holes 320 in a
circular path and further passes through a catheter wire passage
324 within the guiding catheter 312, forming a large loop. The free
ends of the thin wire 322 are found on the end opposite of the
electrical block device 300 of the guiding catheter 312. Such a
design allows the tension of wire 322 to control the expansion
state of the expandable ring 302.
[0106] The overall operation of this electrical block device 300 is
similar to the previously mentioned embodiments above. The user
positions the guiding catheter 312 near the bifurcation 316 of the
pulmonary veins, then attaches the anchoring clip 306 using the
guide wires 310 to assist in proper positioning. Next, the user
manipulates the thin wire 322 to relieve the compression of
expandable ring 302, allowing the ring 302 to expand to its full
diameter, pressing against the target tissue.
[0107] To remove the wire 322 from the electrical block device 300,
a user simply pulls one end of the wire 322 until the opposite end
is free of both the electrical block device 300 and the guiding
catheter 312. At this point, the electrical block device 300 and
the guiding catheter 312 are no longer connected, so the user may
remove the guiding catheter from the patient, allowing the
electrical block device 300 to function as intended.
[0108] This technique of controlling the deployment of the blocking
device with a tether wire is shown here for a bifurcated ostium. It
is anticipated that this same technique can be applied for other
ostial geometries as will be described below.
[0109] Alternative Electrical Block Device Designs
[0110] It should be understood that variations on the above
described electrical block devices are possible and even desired,
depending on a number of factors such as the geometric layout of
the ostium of the pulmonary veins. Five variations may be seen in
the preferred embodiments of FIGS. 10-13. Consistent with the
previous embodiments, these alternative embodiments similarly
employ an anchoring structure and an expandable ring structure.
[0111] Referring to FIG. 10, an electrical block device 400 is
comprised of an expandable ring 402. Unlike previously described
expandable rings, this expandable ring 402 has an overall warped
structure, lending itself to placement analogous to a saddle over a
bifurcation in a pulmonary ostium. In one variation, the expandable
ring 402 includes anchoring barbs 403 to assist in securing the
expandable ring 402 in place. In another embodiment (not shown),
the anchoring barbs 403 may be absent and the expandable ring 402
is secured in place according to the expansion force of the ring
402 (based at least in part on the size and thickness of the ring
402) against the surrounding tissue.
[0112] In this embodiment, the expandable ring 402 has a wave-like
structure similar to previously described embodiments, yet its
overall conformation curves upward at the outer sides of the
pulmonary veins while the inner portion warps downward toward the
left atrium. This overall bent configuration allows the electrical
block device 400 to wedge into place at the ostium of the pulmonary
veins.
[0113] Referring to FIG. 11, an electrical block device 404 is
shown to have an expandable wire ring 408 and an expandable vein
anchor 406. The wire ring 408 is an incomplete, non-continuous
circle, formed to a diameter larger than the target pulmonary
ostium which allows the wire ring 408 to self-expand against the
target tissue.
[0114] The expandable vein anchor 406 has a circular wave-like
(sinusoidal) structure which seats in a branch of the pulmonary
vein just past the bifurcation and is connected to the expandable
wire ring 408 with at least one wire. The vein anchor 406 has a
similar structure to wave-like expandable rings described in
previous embodiments. Functionally speaking, the vein anchor 406
expands in diameter against the pulmonary vein tissue providing
additional anchoring force to secure the electrical block device
404 to the target position.
[0115] A variation of the embodiment in FIG. 11 is shown in FIG.
11A. This embodiment of an electrical conduction block device 700
uses a similar expandable wire ring 702 and an expandable vein
anchor 704 connected by a connecting wire 706. However, the
expandable vein anchor 704 in this embodiment is helical as shown
in FIG. 11A.
[0116] FIG. 12 illustrates yet another preferred embodiment of an
electrical block device 410, this embodiment having an expandable
ring 412 and dual ring anchors 414. As with previous embodiments,
the expandable ring 412 is formed to have a diameter larger than
the target ostium diameter, and is designed for seating close to
the pulmonary ostium.
[0117] Each of the dual vein anchors 414 seats within a branch of
the pulmonary vein, just past the bifurcation, and self expands to
a diameter larger than the target diameter of the pulmonary vein
and thereby is secured against the pulmonary vein tissue. Wire
supports 411 connect the dual vein anchors 414 to the expandable
ring 412 and thereby secure the electrical block device 410 in
place.
[0118] Turning now to FIG. 13, yet another preferred embodiment of
an electrical block device 416 is illustrated. Although this
embodiment also is usable with many ostial geometries, it is
especially useful with pulmonary ostium having no bifurcation, as
seen in FIG. 13. Further, multiple electrical block devices 416 can
be used for each patient, typically using one electrical block
device for each pulmonary vein to provide complete electrical
isolation between the left atrium and the pulmonary veins.
[0119] In this embodiment, the electrical block device 416 has an
outer expandable ring 420 and an inner expandable ring 418. Both
rings 420, 418 are secured together by wire support 422. The inner
expandable ring 418 seats within a pulmonary vein, pressing
outwardly against the vein tissue while the outer expandable ring
420 seats around the opening of the pulmonary vein. This embodiment
allows the two rings to have either common or different functions.
They can both be used to generate scarring as described above. They
can also be configured such that the inner expandable ring 418 acts
primarily as an anchoring/positioning ring and thereby allows outer
expandable ring 420 to be held against the tissue around the ostium
and to thereby serve as the scar generating ring.
[0120] Both rings 418, 420 have an angular wave-like design,
allowing for compression in diameter during the pre-deployment
phase and self-expansion during the deployment phase. In this
fashion, electric block device 416 provides an alternative design
for varying pulmonary geometries.
[0121] Electrical Block Device Coatings
[0122] The electrical block devices of the present invention as
disclosed herein may be coated with a variety of chemicals or drugs
to further enhance functionality. Such coatings may include drugs,
chemicals, proteins, or other materials.
[0123] In one preferred embodiment of the present invention,
portions of the electrical block device are coated with stenosis
inhibiting drugs such as rapamycin or pacitaxel, as described in
U.S. Pat. Nos. 6,273,913 and 6,231,600, the contents of which are
hereby incorporated by reference.
[0124] The portions of the electrical block device which extend
into the pulmonary vein may be of the most interest to coat, so as
to limit the risk of pulmonary vein stenosis caused by the
anchoring component of the implant yet not impacting the scarring
response to the expandable ring desired in the ostium.
[0125] In another preferred embodiment, portions of the electrical
block device are coated with a polymer material such as urethane or
polyester, in order to promote the desired scarring around the ring
while the anchoring components could remain uncoated or have a
stenosis inhibiting coating as described above. Such a polymer
coating could also be bio-absorbable, allowing for partial
integration into the target tissue area.
[0126] In a further preferred embodiment, the expandable ring has a
scar-inducing coating for enhancing the electrical blocking scar
formation created by the expandable ring. Such coatings may include
polymers, bioabsorbable polymers, platings (e.g., copper), polymers
loaded with drugs (e.g., tetracycline), or drugs alone.
[0127] Expandable Ring Variations
[0128] Although the expandable electrical conduction block device
of the present invention has been described in previous embodiments
as primarily relying on a single zigzagging ring, it should be
understood that a number of more complex variations are possible.
Each variation may have different advantages beneficial to
different pulmonary ostia geometries.
[0129] In a preferred embodiment seen in FIGS. 14-16, an expandable
electrical conduction block device 500 is illustrated having a
primary ring 504 (or primary "cell") and a secondary ring 502 (or
secondary "cell"), formed from a single piece of material. As with
previously described conduction block devices, this design may be
compressed to a smaller size for loading into a deployment sheath
or other deployment device so that it expands to a large diameter
when free of such deployment devices. FIGS. 14 and 15 shows the
conduction block device 500 in an expanded state while FIG. 16
shows a sliced and flattened section of the device 500 in an
unexpanded state.
[0130] The electrical conduction block device 500 has a primary
ring 504 connected to a secondary ring 502 at the angled bend
points or strut connection points of each ring. The primary ring
504 has a wider strut than the secondary ring 502, increasing the
stiffness of the primary ring 504, while the secondary ring 502 is
shorter in circumference than the primary ring 504. The differing
circumferences of each ring allows for an expanded shape seen in
FIG. 14, with the secondary ring 502 fully extended to an
essentially unbent circle and primary ring 504 extended to an
overall wavy/sinusoidal shape. In a preferred embodiment, anchoring
barbs 506 are present at the angled bend points of primary ring
504, providing additional anchoring force to maintain the target
position of the electrical block device.
[0131] This two-ringed or two-cell design has a number of
advantages, one of which is increased force per area on the target
tissue by the secondary ring 502 relative to the primary ring 504.
In this regard, the radial force exerted by the device against the
wall of the target vessel is driven in large part by the width of
the ring material. In other words, a wider ring can expand with
more force than a thinner ring. A tissue necrosis mechanism for
creating scars is a function of the pressure (force per unit area)
exerted by the electrical block device against the target tissue.
Since the primary ring 504 is wider than the secondary ring 502 and
the two rings are connected together (allowing some of the radial
expansion force generated by the primary ring 504 to be applied to
the tissue contacted by the secondary ring 502), the secondary ring
502 thus causes a greater amount of force per area as between the
two. As a result, the secondary ring 502 can be designed to create
a desired scar line while the primary ring 504 can be designed to
provide the primary anchoring function.
[0132] In this regard, FIGS. 17A and 17B provide a cross-sectional
view of how the secondary ring 502 causes the scarring response.
FIG. 17A shows the placement of the conduction block device 500
immediately after placement of the device 500 at the target site.
As is evident, the barbs 506 have initially engaged the tissue wall
but there is not yet any migration of the device into the tissue
wall nor any scar line.
[0133] FIG. 17B, on the other hand, shows the configuration of the
conduction block device 500 after migration has occurred. As is
evident in this embodiment, the greater force per area of the
secondary ring 502 has caused the barbs 506 on the top end of the
secondary ring 502 to extend into and even break through the tissue
wall whereas the barbs 506 at the lower end of the primary ring 504
remain embedded in the tissue wall thickness. As is also evident,
this migration has caused the creation of a scar line (indicated by
the shaded area 503), including a scar line 503 that traverses the
entire thickness of the tissue wall and encases or encapsulates the
barb 506 of the secondary ring 502 that has extended through the
tissue wall.
[0134] Another advantage to the dual ring design of the expandable
ring 500 is that the secondary ring 502 is stretched into a nearly
straight circle thereby allowing the secondary ring 502 to inscribe
a substantially straight scar line around the internal
circumference of the pulmonary vein. That is, the substantially
straight scar line created by the secondary ring 502 avoids forming
a scar line that extends axially upstream in the vein (away from
the atrium) as would be the case if the secondary ring 502 was
configured to have a wave-like shape in the deployed state.
[0135] This is important insofar as the electrical sources that
must be isolated from the atrium in treating atrial arrhythmias are
suspected to reside in close proximity to the ostium. These sources
may be missed or inadequately isolated if the scar line, or a
portion of the scar line, is created too far upstream in the vein
(away from the atrium). Additionally, as discussed previously, the
anatomy around the ostium often includes side branches or curves
which make it more difficult to create a full circumferential scar
line with a wave-like ring.
[0136] Finally, the electrical block device 500 that uses two rings
(or "cells") in this manner allows the formation of a discrete,
narrow scar line yet has the positional stability of an axially
extensive implant. In other words, the use of two rings 502, 504 in
this manner leads to a narrow scar line around the ostium and also
provides sufficient axial length so as to better ensure proper
deployment and retention at the site. This is important as it is
known that implants that have an increased ratio of diameter to
axial length are more prone to misdeploy or "tumble" during
deployment.
[0137] In a preferred embodiment of the expandable ring 500, the
primary ring 504 and the secondary ring 502 are cut from a single
tube of memory elastic metal, such as nitinol as shown in FIG. 16.
Each ring 502, 504 of the tubular structure is then stretched over
a larger diameter ring and heat set in a furnace at about 540
degrees Celsius. The final formed diameter of each should allow the
secondary ring 502 to stretch out to almost a straight circle as
shown in FIGS. 14 and 15. The formed diameter of the expandable
ring 500 is preferably larger in diameter than the target vessel by
5-100%, and more preferably by about 15% to 40%.
[0138] Electro-polishing components of the expandable ring 500 may
be necessary to prevent micro surface cracks from propagating when
the device is strained in forming. These cracks can cause the
device to fracture and must be eliminated by polishing before
applying high strain to the components. Nitinol components of the
expandable ring 500 can be electro-polished using percloric acid,
nitric acid, or other compounds known to one skilled in the art. It
may be desirable to form the device to a higher diameter in which
case electro-polishing in stages may be necessary. This results
from the fact that some expansion may be needed before being able
to polish uniformly and from the fact that polishing may need to
precede final expansion.
[0139] FIGS. 18 and 19 show two possible other formed geometries
for the conduction block device 500 described with reference to
FIG. 16. FIGS. 18 and 19 show the end of the device 500 with the
secondary ring 502 being formed to a larger diameter than the end
of the primary ring 504 without the secondary ring 502. As
described earlier, the ratio of the diameter of the formed device
to the diameter of the target site for the implant is an important
driver of the magnitude of the radial force exerted by the device
against the tissue of the target site. By forming the device
tapered as in FIG. 18 or flared as in FIG. 19, it is possible to
produce higher pressures against the tissue under the secondary
ring 502 than under most if not all of the primary ring 504. This
is independent of the pressure differences resulting from the width
differences between the two rings as described previously. The
result of this configuration is to have the secondary ring 502
apply enough pressure against the tissue wall to migrate through
the wall due to pressure necrosis while most, if not all, of the
primary ring 504 applies less pressure against the tissue so that
it secures the position of the device 500 while creating reduced
necrosis or fibrosis or, in some cases, perhaps no necrosis or
fibrosis.
[0140] Referring to FIGS. 20-22, another embodiment of an
electrical block device 511 is shown. As with the embodiment of
FIGS. 14-16, this electrical block device 511 includes a primary
ring 508 and a secondary ring 514. However, each ring 508, 514 is
formed separately and later assembled to create the electrical
block device 511 as discussed below.
[0141] The primary ring 508 has a wave shape in its expanded form
as shown in FIG. 20. It is formed from a tube with the cut path
around the circumference of the tube shown in FIG. 21. It includes
barbed securing spikes 510 and anchoring spikes 512, as also is
seen in FIG. 18. These securing spikes 510 are sized to fit within
spike apertures 515 that are disposed on the secondary ring 514
which is depicted in FIG. 22. Thus, by inserting the barbed
securing spikes 510 of the primary ring 508 into the spike
apertures 515 of the secondary ring 514, the unitary electrical
block device 511 is formed. The assembled device 511 may then be
compressed and expanded as needed for loading and deployment as
discussed with previous embodiments. This embodiment allows the
secondary ring 514 to project radially out further than the primary
ring 508 as shown in FIG. 20. This can aid in focusing the pressure
against the tissue to the areas contacted by secondary ring
514.
[0142] Referring to FIG. 23, an alternate preferred embodiment may
comprise a secondary ring 516 that functions as described with
previous embodiments but that further includes a plurality of
points 519 arranged around its outer edge. These points provide
additional anchoring force, as well as additional scarring
capability for the secondary ring 516.
[0143] Referring to 24 and FIG. 24A, another preferred embodiment
of an electrical block device 535 is contemplated wherein the
primary ring 536 has struts 537 that are longer than the struts of
the primary ring of previous embodiments. Furthermore, the
secondary ring 538 is attached to the primary ring 536 with
connection strands 533 that extend from the bottom of the secondary
ring 538 to the bottom of the struts 537 of the primary ring. This
differs from previously described embodiments wherein the secondary
ring 538 is connected to the top of the struts of the primary ring
536. As a result, a higher percentage of the main expansion force
generated by the primary ring 536 is delivered through the
secondary ring 538. It also leads to the primary ring 536 extending
axially beyond the secondary ring 538 whereas in previous
embodiments, the primary ring is essentially below the secondary
ring.
[0144] An advantage to this configuration is as follows. The larger
surface area provided by the primary ring 536 leads to a greater
dispersion of the expansion pressure (force per unit area) against
the tissue by the primary ring 536 and thus mitigates (or even
eliminates) the tendency of the struts of the primary ring 536 to
penetrate or migrate through the wall of the vessel tissue. At a
minimum, this greater surface will slow down the migration rate of
the struts as compared to other embodiments and as to the struts of
the secondary ring 538. It does not, however, negatively affect the
desired expansion pressure (force per unit area) of the secondary
ring 538. Hence, a first advantage is that the primary ring 536 may
better facilitate the anchoring properties of the device 535
without degrading the scar inducing properties of the secondary
ring 538.
[0145] Another advantage of this configuration relates to how the
scar inducing properties of the device are executed by the device
535. If the struts 537 of the primary ring 536 are prevented from
migrating into the wall of the tissue, this will better ensure the
proper migration of the struts of the secondary ring 538. For
example, if the struts of one side of the secondary ring 538
migrate fully through the wall on one side of the vessel before
similar migration by the struts on the other side of the secondary
ring 538, the circumferential tension (caused by the vessel tissue)
necessary for urging the oppositely sided struts to continue their
migration will be released unless an independent force is exerted
against these oppositely sided struts. This independent force is
provided by the struts 537 of the primary ring 536 as follows.
Since the struts 537 of the primary ring 536 have not migrated into
the tissue (by virtue of the larger surface area of these struts),
they retain their expansion force. And because these struts 537 are
independently connected to the struts of the secondary ring 538,
then the oppositely sided struts of the secondary ring 538 will
continue to encounter the outward expansion forces of the primary
ring 536. As a result, uniform migration of the struts of the
secondary ring 538 into the surrounding tissue is substantially
assured even if the migration of the entire circumference of the
secondary ring 538 does not occur simultaneously. In other words,
by having the primary ring 536 serve essentially only as an
anchoring ring (by virtue of its increased area), uniform outward
expansion force is exerted against the struts of the secondary ring
538, regardless of when a portion of the secondary ring may migrate
through the vessel tissue.
[0146] Referring to FIG. 25, a variation of the embodiment of FIGS.
24 and 24A may include an electrical block device 520 wherein the
struts 525 of the primary ring 522 not only extend beyond the
struts of the secondary ring 524 but the struts 525 are configured
to flare outwardly beyond the normal diameter of the device 520.
Configuring the struts 525 in this matter allow the electrical
block device 520 to better conform to the structure of the ostium
and pulmonary vein since typically the ostium expands outwardly as
it merges with the atrial wall. This configuration may cause the
primary ring 522 to have even better anchoring properties than the
embodiment of FIGS. 24 and 24A.
[0147] Referring to FIGS. 26 and 27, another preferred embodiment
for causing tissue scarring with an expandable ring is an
electrical conduction block device 530 that includes a series of
small barbs 532 along the length of each strut 531 of the device
530. These barbs 532 serve to pierce the tissue wall of the vessel
at the same time that the device 530 is being expanded against the
vessel wall. The barbs 532 create small cuts along the pressure
path and thereby reduce the pressure (force per unit area) needed
for each strut 531 to migrate through the vessel wall.
[0148] The barbs can be cut in the pattern shown in the flat sheet
depiction of the device 530 in FIG. 27, wherein the barbs 532 lay
flat, i.e., they lay circumferentially on the device instead of
radially outwardly. The barbs 532 can then be bent into a radially
outward position when the device is formed up to its final
diameter. Typically this occurs automatically if the ratio of strut
thickness to strut width is decreased below about 1.0.
[0149] Furthermore, the embodiment depicted in FIGS. 26 and 27 can
be used alone, i.e., as the sole component of the electrical
conduction block device or it can be used in a two-ring or
"two-cell" design as discussed previously. Referring to FIG. 27,
the device 530 can serve as a primary ring as in previously
described embodiments wherein a secondary ring can be connected via
the apertures that are located at one end of the struts 531 of the
device 530.
[0150] It is desirable to deploy the device in a very controlled
and accurate way for all embodiments of the electrical block
devices discussed in accordance with the present invention. This
includes the capability of deploying the device with a smooth
release from the delivery device with no "jumping" of the position
of the device in the target vessel. It also includes the capability
of repositioning the device or to remove the device if the
physician is not pleased with the deployed position of the
device.
[0151] One embodiment of such a delivery system useful particularly
for the electrical block devices described previously with respect
to FIGS. 13-27 is shown in FIGS. 28A-28C. FIG. 28A shows an
electrical block device 500 having a primary 504 and secondary ring
502 being deployed out of the end of the delivery catheter 700 into
the ostium of a pulmonary vein. This deployment is initiated by
drawing back the external sheath 702 to allow the block device 500
to expand up towards its formed diameter.
[0152] FIG. 28B shows the electrical block device 500 now fully
expanded at the site in the ostium of the pulmonary vein ostium. In
this drawing it can be seen that the electrical block device 500 is
attached to the delivery catheter 700 by an array of arms 539
projecting out from a hub 704 on the inner shaft 705 of the
delivery catheter 700. These arms 539 are connected to the
secondary ring 502 of the electrical block device 500. This array
of arms 539 connected to the electrical block device 500 allows the
deployment of the device 500 to be controlled according to the rate
the outer sheath 702 is pulled back. In the partially deployed
state shown in FIG. 28A, the sheath 702 constrains the expansion of
the arms 539 which then act to hold down the electrical block
device 500.
[0153] This type of an assembly allows the device 500 to be
deployed gradually by controlling the rate that the sheath 702 is
pulled back along the catheter. This assembly also allows recovery
or repositioning of the electrical block device 500 if the
physician so wishes by advancing the sheath 702 back over the arms
539 and the electrical block device 500. FIG. 28C shows the
delivery catheter 700 being withdrawn away from the deployed
electrical block device 500 after releasing the connection of the
arms 539 from the device 500.
[0154] FIGS. 29A-29C show a variation on delivery catheter design
described above. In this embodiment the loops formed by the
secondary ring 502 of the fully constrained electrical block device
500 shown in FIG. 16 are used to connect the electrical block
device 500 to the delivery catheter 700. These loops are hooked
over a ring of pins 540 and are thereby trapped inside the sheath
702 of the delivery catheter 700 until the sheath 702 is withdrawn
back beyond the ring of pins 540. FIG. 29B shows how this allows
the primary ring 504 to be deployed while retaining connection to
the secondary ring 502 inside the end of the sheath 702. If
satisfied with the location of the primary ring 504, the sheath 702
is then withdrawn fully releasing the secondary ring 502 as shown
in FIG. 29C.
[0155] FIG. 30 shows one embodiment in which the arms 539 are
hollow tubes having a wire 708 running from the handle of the
catheter 700, down the shaft of the catheter to the array of arms
539, then inside the arm and out the end. This wire 708 is then
wrapped around the strut of ring 502 and back into the arm 539.
This wire 708 runs back down the arm to a releasable anchor point
(not shown) in the catheter 700 shaft or back in the handle (not
shown). This connects the arm 539 to the strut 502. After the
electrical block device 500 has been deployed, the device 500 can
be released by releasing the anchor point on the wire 708 and
pulling the wire 708 out from the catheter handle as is shown in in
the far right view of FIG. 30.
[0156] FIG. 31 shows another embodiment of a connecting mechanism
in accordance with the invention. In this embodiment, the strut of
the secondary ring 502 has a notch 710 which provides a nest for a
mating notched end of the arm 539. Arm 539 has a wire 708 running
along it from the catheter handle like that described with respect
to FIG. 30. This wire 708 runs through holes 712 in the arm 539 on
either side of the strut 502 forming a loop around the strut. The
mating notches between the strut 502 and the arm 539 act to absorb
any axial load that may occur between these two elements during
delivery. The connection may be released after deployment of the
electrical block device 500 by pulling the wire 708 back through
the holes 712 from the catheter handle as shown in right views of
FIG. 31.
[0157] FIG. 32 shows another embodiment of a connecting mechanism
in accordance with the present invention. In this embodiment, the
strut of the secondary ring 502 has a small hole 714 cut in it. The
end of the arm 539 has a "U" shaped cradle 716 with holes 718 cut
in each side of the cradle 716. The strut is placed in this "U"
shaped cradle 716 during assembly and a small pull wire 708 as
described previously relative to FIGS. 30 and 32 is threaded
through the holes 718 in the "U" shaped cradle 716 and the strut
502. After
[0158] deployment of the electrical block device 500, this
connection can be released by pulling this wire 708 back through
these holes 714, 718 as shown in the right views of FIG. 32.
[0159] FIG. 33 shows another embodiment of a connecting mechanism
in accordance with the present invention. In this embodiment, the
strut of the secondary ring 502 has a small hole 720. This hole 720
has a pair of wires 722, 724 strung through it. One of these wires
722 has an increased diameter 726 on its end that will fit through
the hole 720 when it is the only wire passing through the hole 720
but will not fit back through the hole 720 if the second wire 724
has been passed through the hole 720 after the increased diameter
end 726 of the first wire 722 has passed through the hole 720. In
this way, the second wire 722 acts as a pin to "lock" the first
wire 724 through the hole 720. This process can be reversed as
shown in FIG. 33 by withdrawing the second wire 724 and then
withdrawing the first wire 722 through the hole 720.
[0160] As mentioned earlier, the concepts disclosed relative to the
previously discussed connecting mechanisms could also be used to
attach a delivery device to the electrical block device 500 at
locations other than the strut of the secondary ring 502 as shown
above. For example, a connecting mechanism such as is shown in FIG.
33 could also be well suited to a hole geometry such as that shown
in FIG. 9. In this case the pairs of wires 722, 724 would extend
radially out from the shaft of the catheter 700 to pass through the
holes in the blocking device. These wires could be radially
extended or drawn back with a handle connected to these wire pairs.
In this way the wires could be used to control the radial expansion
of the electrical block device 500 as was described earlier, and be
released from the electrical block device 500 when desired by
withdrawing the second wire and then the first wire as shown in
FIG. 33.
[0161] Variably Expandable Electrical Block Device
[0162] Yet another preferred embodiment of the present invention
illustrates a variably expandable electrical block device 600 and
deployment apparatus 616, illustrated in FIGS. 34-45. Generally,
this device 600 functions in a manner similar to previously
described embodiments by causing scarring at the ostium of the
pulmonary veins. However, the structure of the variably expandable
electrical block device varies from previous designs in that it
utilizes a non-continuous expandable ring 602 that allows for
compact loading and deployment.
[0163] FIG. 34 shows the non-continuous expandable ring 602 in its
flattened, loaded position, while FIG. 35 shows the ring 602 in its
natural coiled position. The expandable ring 602 has two notable
elements: anchoring barbs 604 and ring wire holes 606. As the name
implies, anchoring barbs 604 provide anchoring support by
penetrating the target tissue when the expandable ring 602 is in
its natural coiled position. This anchoring support prevents the
expandable ring 602 from migration away from the target area while
securing portions of the expandable ring 602 to the ostium. Ring
wire holes 606 are simply holes within expandable ring 602 that
allow a control wire 618 to pass through.
[0164] Referring to FIG. 36, the deployment device 616 is shown to
have a deployment sheath 614 and a deployment catheter 612. The
deployment catheter 612 is an elongated instrument that slides
within deployment sheath 614. Located on the end of deployment
catheter 612 are control arms 608, preferably made from nitinol,
which serve to deploy the expandable ring 602 at a target location
as discussed in greater detail below. Control arm wire holes 610
can be seen at the ends of each control arm 608, allowing for
control wires 618 to pass through each of the holes 610 and into a
center channel (not shown) of the deployment catheter 612.
[0165] Referring to FIGS. 37 and 38, the present preferred
embodiment uses two control wires 618 for manipulating the
expandable ring 602. Each control wire 618 takes an overall looped
path, extending out of and through the center channel in deployment
catheter 612, through a control arm wire hole 610, into ring wire
hole 606, across the diameter of the deployed expandable ring 602,
then through the opposite side's ring wire hole 606, into an
opposite control arm wire hole 610, and finally into the center
channel in deployment catheter 612. Each control wire 618
consequently crosses the diameter of expandable ring 602 such that
that when both control wires 618 are present, an "X" pattern spans
the diameter of the expandable ring 602.
[0166] A user may tighten or loosen these two control wires 618 to
manipulate the size of the expandable ring 602. FIGS. 42 and 43
best illustrate this function, as the expandable ring 602 is shown
in an expanded and contracted position, respectively.
[0167] The control wires 618 also serve the secondary function of
deflecting the anchoring barbs 604 inward to prevent the sharp tips
from being exposed until the control wire 618 is withdrawn. This
deflection can be best seen in FIG. 39.
[0168] Referring to FIG. 40, the variably expanding electrical
block device 600 can be seen in a loaded state within the
deployment sheath. As with previous embodiments of the present
invention, the expandable ring 602 remains within the deployment
sheath 614 until the end of the deployment sheath reaches the
target location of the pulmonary ostium. Note that control wires
618 are not shown for simplicity of illustration.
[0169] One of the inherent benefits of this design lies in its
ability to pass through significantly smaller diameter deployment
sheaths for delivery to the desired target site, while expanding to
an appropriate diameter, similar to the previously disclosed
embodiments of this application.
[0170] Preferably, the expandable ring 602 could be cut from a flat
sheet or tubing made from nitinol, having a thickness of about
0.015 inches and a height of about 0.070 inches. However, a variety
of thicknesses and heights may be used so long as loading into a
deployment sheath is possible and proper expansion of the
expandable ring 602 may be achieved.
[0171] This embodiment of the present invention may be operated by
first finding the pulmonary ostium target area with the loaded
deployment apparatus 616 as depicted in FIG. 40. Referring to FIGS.
40 and 37, the user pushes deployment catheter 612 within the
deployment sheath 614, which, in turn, pushes expandable ring 602
out from the deployment sheath 614. The user continues pushing the
deployment catheter until control arms 608 are fully extended from
the deployment sheath. During this movement, the expandable ring
602 curls back on itself from its straight shape, forming its
relaxed, circular ring shape. This results in the system having the
configuration depicted in FIG. 37 in the left atrium.
[0172] Referring to FIGS. 41, 42 and 43, the user is able to
control the diameter of expandable ring 602 for purposes of
matching the ring with the target site by simply pulling on the
control wires 618 to decrease the diameter and/or releasing the
wires to increase the diameter. Typically, a user will pull the
control wires 618 to decrease the expandable ring 602 diameter so
as to allow the user to then easily position the ring 602 at the
target position of the ostium.
[0173] In this regard, the control arms 608 are devised so as to
have sufficient axial strength so that the user may use them to
push the expandable ring 602 forward. The user can track along a
guide wire until either the expandable ring 602 wedges into the
ostium or until the ring 602 is aligned with a predetermined axial
marker of the desired deployment position.
[0174] Referring to FIGS. 44 and 45, once the proper target
position is achieved, the user releases the control wires 618 which
then allow the expandable ring 602 to increase in diameter, pushing
against the target tissue. When the user is satisfied that the
expandable ring 602 is in the proper position, the final step of
deployment is performed, namely separating the deployment apparatus
616 from the expandable ring 602. To do this, a user must first
remove control wires 618 from the expandable ring 602 by pulling on
one end of each control wire 618. Since only one end of the control
wire 618 is being pulled, the opposite end will be pulled through
its path in the expandable ring 602 and out of the control end of
the deployment catheter 612. Each control wire 618 is pulled out of
the electrical block device 600 in a similar manner.
[0175] When all of control wires 618 are pulled out, the anchoring
barbs 604 are free to bend outwardly from the expandable ring 602
and penetrate the target tissue. Additionally, the deployment
apparatus 616 is free to be retracted and removed from the patient,
and the procedure may be finished, as best seen in FIG. 44 and
45.
[0176] Optionally, additional anchoring devices may be used to help
secure the electrical block device. Typically, such devices include
staples or sutures which are not integral parts of the ring but
which are delivered with a separate device that can be tracked into
position and fasten the expandable ring to the tissue wall.
[0177] Although the invention has been described in terms of
particular embodiments and applications, one of ordinary skill in
the art, in light of this teaching, can generate additional
embodiments and modifications without departing from the spirit of
or exceeding the scope of the claimed invention. Accordingly, it is
to be understood that the drawings and descriptions herein are
proffered by way of example to facilitate comprehension of the
invention and should not be construed to limit the scope
thereof.
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