U.S. patent application number 11/763372 was filed with the patent office on 2008-12-18 for cryogenic balloon ablation instruments and systems.
This patent application is currently assigned to Boston Scientific Scimed, Inc.. Invention is credited to Michael Fourkas, Kurt Geitz, Kristine Tatsutani, Steven Walak.
Application Number | 20080312644 11/763372 |
Document ID | / |
Family ID | 39712056 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080312644 |
Kind Code |
A1 |
Fourkas; Michael ; et
al. |
December 18, 2008 |
CRYOGENIC BALLOON ABLATION INSTRUMENTS AND SYSTEMS
Abstract
Cryogenic tissue ablation instruments for treating body tissue
include an elongate flexible body with a proximal supply port for
coupling with a pressurized coolant (e.g., liquid N.sub.2O), a
supply lumen in fluid communication with the proximal supply port,
and an expandable cryogenic balloon carried on a distal portion of
the elongate body, the balloon having a wall defining an interior
of the balloon. A dispersion member coupled to or otherwise formed
out of a distal end portion of the elongate body has an interior
lumen in fluid communication with or otherwise comprising a portion
of the supply lumen, the dispersion member having one or more
coolant dispersion apertures in fluid communication with the
balloon interior and sized and located with respect to the balloon
wall such that a pressurized flowable coolant in the supply lumen
will enter the balloon interior through the one or more apertures
in the form of a liquid spray that contacts and provides (through
rapid evaporation) substantially uniform cooling of an interior
wall surface of a treatment region of the balloon.
Inventors: |
Fourkas; Michael;
(Sunnyvale, CA) ; Walak; Steven; (Natick, MA)
; Geitz; Kurt; (Sudbury, MA) ; Tatsutani;
Kristine; (Redwood City, CA) |
Correspondence
Address: |
VISTA IP LAW GROUP LLP
12930 Saratoga Avenue, Suite D-2
Saratoga
CA
95070
US
|
Assignee: |
Boston Scientific Scimed,
Inc.
Maple Grove
MN
|
Family ID: |
39712056 |
Appl. No.: |
11/763372 |
Filed: |
June 14, 2007 |
Current U.S.
Class: |
606/22 |
Current CPC
Class: |
A61B 2017/00084
20130101; A61B 2018/0212 20130101; A61B 2018/0022 20130101; A61B
2090/3937 20160201; A61B 2017/22051 20130101; A61B 90/39 20160201;
A61B 18/02 20130101 |
Class at
Publication: |
606/22 |
International
Class: |
A61B 18/02 20060101
A61B018/02 |
Claims
1. A cryogenic tissue ablation instrument, comprising: an elongate
flexible body having a proximal supply port adapted for coupling
with a source of pressurized flowable coolant, and a supply lumen
in fluid communication with the proximal supply port and extending
through the elongate body to a distal portion thereof; a dispersion
member coupled to or formed out of the distal portion of the
elongate body, the dispersion member including an interior lumen in
fluid communication with or otherwise comprising a portion of the
supply lumen; and an expandable balloon carried on the distal
portion of the elongate body and having a wall, an interior surface
of the wall defining an interior of the balloon, the dispersion
member at least partially extending into the balloon interior and
having a plurality of coolant dispersion apertures in fluid
communication with the respective supply lumen and balloon
interior, wherein the coolant dispersion apertures are sized and
located on the dispersion member such that a pressurized flowable
coolant provided in the supply lumen will enter the balloon
interior through the dispersion apertures in the form of a liquid
spray that contacts and provides substantially uniform cooling of
the interior wall surface of a treatment region of the balloon.
2. The instrument of claim 1, the treatment region includes an
entire circumference of the balloon.
3. The instrument of claim 1, wherein the balloon is semi-compliant
or compliant.
4. The instrument of claim 1, wherein at least two of the coolant
dispersion apertures are offset axially on the dispersion member
within the balloon interior.
5. The instrument of claim 4, the axially offset apertures
including a first aperture having a first aperture size, and a
second aperture located distally on the elongate member from the
first aperture and having a second aperture size greater than the
first aperture size.
6. The instrument of claim 1, wherein at least two of the coolant
dispersion apertures are offset circumferentially on the dispersion
member within the balloon interior.
7. The instrument of claim 6, the dispersion member comprising a
first plurality of circumferentially spaced coolant dispersion
apertures, and a second plurality of circumferentially spaced
coolant dispersion apertures located distally on the dispersion
member from the first plurality.
8. The instrument of claim 1, wherein the coolant dispersion
apertures have shapes selected from the group comprising circular,
rectangular, and elliptical.
9. The instrument of claim 1, the balloon having a collapsed
delivery profile sized for passage through a working channel of an
endoscopic instrument into a human esophagus, and an expanded
treatment profile sized such that, when the balloon is transitioned
from its collapsed delivery profile to its expanded treatment
profile, an exterior wall surface of the balloon contacts and
smoothes the esophageal wall tissue.
10. The instrument of claim 9, wherein the balloon is
semi-compliant or compliant.
11. The instrument of claim 1, the balloon wall having an exterior
surface comprising or coated with a lubricious material.
12. The instrument of claim 1, the balloon wall comprising a
polymer material and a non-polymer material, the non-polymer
material having a greater thermal conductivity than the polymer
material.
13. The instrument of claim 12, the non-polymer material
distributed in the balloon in such quantity and configuration so as
to substantially increase the thermal conductivity of the balloon
above the conductivity it would have in the absence of the
non-polymer material.
14. The instrument of claim 12, the non-polymer material comprising
metallic strips, fibers, or particles.
15. The instrument of claim 12, wherein the non-polymer material is
attached to or embedded in the balloon wall.
16. The instrument of claim 12, the non-polymer material comprising
a plurality of circumferentially spaced metallic strips.
17. The instrument of claim 12, the non-polymer material comprising
a plurality of longitudinally spaced metallic strips.
18. The instrument of claim 1, the balloon wall comprising a
material allowing for direct visualization through the balloon
wall.
19. The instrument of claim 1, further comprising thermochromic
material carried on or in the balloon wall, the thermochromic
material selected so as to undergo a visual change in appearance
when the balloon wall reaches a selected tissue ablation
temperature.
20. A system including the instrument of claim 1, wherein the
source of pressurized flowable coolant is fluidly coupled to the
proximal supply port, and further comprising a controller
operatively coupled with the source of pressurized flowable coolant
so as to controllably release the coolant into the supply
lumen.
21. The system of claim 20, further comprising one or more
temperature sensors carried on or in the balloon wall and
cooperatively coupled to the controller, wherein the controller
regulates release of coolant into the supply lumen based at least
in part on input from the one or more temperature sensors.
22. A cryogenic tissue ablation instrument, comprising: an elongate
flexible body having a proximal supply port adapted for coupling
with a source of pressurized flowable coolant, and a supply lumen
in fluid communication with the proximal supply port and extending
through the elongate body to a distal portion thereof; a dispersion
member coupled to or formed out of the distal portion of the
elongate body, the dispersion member including an interior lumen in
fluid communication with or otherwise comprising a portion of the
supply lumen; and an expandable balloon carried on the distal
portion of the elongate body, the balloon having a wall with an
interior surface of the wall defining an interior of the balloon,
the dispersion member at least partially extending into the balloon
interior and having one or more diffusers provided therein, the one
or more diffusers each configured to direct a the coolant from the
supply lumen in the form of a liquid spray onto the interior
balloon wall surface, wherein the one or more diffusers are sized
and located on the dispersion member such that the liquid spray
contacts and provides substantially uniform cooling of the interior
wall surface of a treatment region of the balloon.
23. The instrument of claim 22, the treatment region includes an
entire circumference of the balloon.
24. The instrument of claim 22, further comprising one or more
deflectors carried on the dispersion member within the balloon
interior, each of the one or more deflectors configured to deflect
at least a portion of the liquid spray onto a respective area of
the balloon wall.
25. A cryogenic tissue ablation instrument, comprising: an elongate
flexible body having a proximal supply port adapted for coupling
with a source of pressurized flowable coolant, and a plurality of
circumferentially spaced coolant supply lumens, each coolant supply
lumen in fluid communication with the proximal supply port and
extending through the elongate body to a distal portion thereof; a
dispersion member coupled to or formed out of the distal portion of
the elongate body, the dispersion member including a plurality of
interior lumens, each in fluid communication with or otherwise
comprising a portion of a respective one of the supply lumens; and
an expandable balloon carried on the distal portion of the elongate
body, the balloon having a wall with an interior surface of the
wall defining an interior of the balloon, the dispersion member
having a portion extending at least partially into the balloon
interior and having respective pluralities of coolant dispersion
apertures formed therein, each plurality of coolant dispersion
apertures in fluid communication with a respective one of the
coolant supply lumens, the collective dispersion apertures sized
and located on the elongate body such that a pressurized flowable
coolant in the respective supply lumens will enter the balloon
interior in the form of a liquid spray that contacts and provides
substantially uniform cooling of the interior wall surface of a
treatment region of the balloon.
26. The instrument of claim 25, the treatment region includes an
entire circumference of the balloon.
27. The instrument of claim 25, the respective pluralities of
coolant dispersion apertures in the dispersion member each
including a first aperture having a first aperture size, and a
second aperture located distally on the dispersion member from the
first aperture and having a second aperture size greater than the
first aperture size.
28. The instrument of claim 25, the coolant dispersion apertures
comprising respective sets of circumferentially spaced apertures
spaced axially on the dispersion member.
29. The instrument of claim 25, the portion of the dispersion
member extending into the balloon interior comprising an expandable
body, the respective coolant dispersion apertures being located on
an exterior facing surface of the expandable body.
30. A cryogenic tissue ablation instrument, comprising: an elongate
flexible body having a proximal supply port adapted for coupling
with a source of a pressurized flowable coolant, a distal portion
sized for introduction into a human esophagus, and a supply lumen
in fluid communication with the proximal supply port and extending
through the elongate body to the distal portion; a dispersion
member coupled to or formed out of the distal portion of the
elongate body, the dispersion member including an interior lumen in
fluid communication with or otherwise comprising a portion of the
supply lumen; and an expandable balloon carried on the distal
portion of the elongate body, the balloon having a wall, an
interior surface of the wall defining an interior of the balloon,
the dispersion member having one or more coolant dispersion
apertures in fluid communication with the respective fluid supply
lumen and balloon interior, the balloon having a collapsed delivery
profile sized for passage through a working channel of an
endoscopic instrument into a human esophagus, and an expanded
profile sized such that, as the balloon is transitioned from its
delivery profile to its expanded profile, the balloon wall contacts
and smoothes the esophageal wall tissue.
31. The instrument of claim 30, wherein in its collapsed delivery
configuration the balloon wall is gathered in longitudinally
oriented folds.
32. The instrument of claim 30, wherein an exterior surface of the
balloon wall comprises or is coated with a lubricious material.
33. A cryogenic tissue ablation instrument, comprising: an elongate
flexible body having a proximal supply port adapted for coupling
with a source of a pressurized flowable coolant and a supply lumen
in fluid communication with the proximal supply port and extending
through the elongate body to a distal portion thereof; a dispersion
member coupled to or formed out of the distal portion of the
elongate body, the dispersion member including an interior lumen in
fluid communication with or otherwise comprising a portion of the
supply lumen; and an expandable balloon carried on the distal
portion of the elongate body, the balloon having a wall, an
interior surface of the wall defining an interior of the balloon,
the dispersion member having one or more coolant dispersion
apertures in fluid communication with the respective supply lumen
and balloon interior, the one or more dispersion apertures being
sized and located in the dispersion member with respect to the
balloon wall such that a pressurized flowable coolant in the supply
lumen will enter the balloon interior through the one or more
apertures in the form of a liquid spray that contacts and provides
substantially uniform cooling of an energy delivery portion of the
balloon wall.
34. The instrument of claim 33, the balloon wall comprising an
insulated portion.
35. The instrument of claim 33, the energy delivery portion of the
balloon wall comprising a distal facing portion of the balloon
wall, the one or more coolant dispersion apertures positioned
relative to the balloon such that a pressurized flowable coolant in
the supply lumen is directed axially in the form of a liquid spray
applied against the interior surface of the respective distal
facing wall portion of the balloon.
36. The instrument of claim 33, the energy delivery portion of the
balloon wall comprising a side facing portion of the balloon wall,
the one or more coolant dispersion apertures positioned relative to
the balloon such that a pressurized flowable coolant in the supply
lumen is directed radially in the form of a liquid spray applied
against the interior surface of the respective side facing wall
portion of the balloon.
37. A cryogenic tissue ablation instrument, comprising: an elongate
flexible body having a distal portion sized for introduction into a
human esophagus, and a plurality of supply lumens in fluid
communication with one or more respective proximal coolant supply
ports and extending through the elongate body to the distal
portion; a dispersion member coupled to or formed out of the distal
portion of the elongate body, the dispersion member including a
plurality of interior lumens, each in fluid communication with or
otherwise comprising a portion of a respective one of the supply
lumens; and an expandable multi-lobe balloon carried on the distal
portion of the elongate body and having a plurality of isolated
balloon chambers, a portion of the dispersion member extending
through a central region of the balloon, each of the coolant supply
lumens being in fluid communication with a respective one of the
isolated balloon chambers via a respective plurality of coolant
dispersion apertures in the dispersion member, the respective
dispersion apertures being sized and positioned on the elongate
body such that a pressurized flowable coolant in one of the supply
lumens will enter the respective isolated balloon chamber through
the respective dispersion apertures in the form of a liquid spray
that contacts and cools of an interior wall surface of the
respective balloon chamber.
38. A system including the instrument of claim 37, wherein the
source of pressurized flowable coolant is fluidly coupled to the
respective one or more coolant supply ports of the instrument, and
further comprising a controller operatively coupled with the source
of pressurized flowable coolant so as to controllable release the
coolant into a respective one or more of the supply lumens.
39. A method of ablating body wall tissue using a cryogenic balloon
instrument, the instrument comprising an elongate flexible member
carrying an expandable balloon on a distal end thereof, the balloon
having a collapsed delivery shape and an expanded treatment shape,
the method comprising: delivering the balloon in its delivery shape
through a working channel of an endoscopic instrument to a location
of the wall tissue to be treated; expanding the balloon so that an
outer surface of the balloon contacts and smoothes the wall tissue
to be treated; and delivering a pressurized flowable coolant from a
source external to the patient through a supply lumen in the
elongate body and out one or more coolant dispersion apertures in
fluid communication with the balloon interior, the one or more
coolant dispersion apertures being sized and located relative to an
interior wall of the balloon such that the pressurized flowable
coolant enters the balloon interior in the form of a liquid spray
that contacts and provides substantially uniform cooling of the
interior balloon wall surface of a treatment region of the
balloon.
40. The method of claim 39, wherein gas formed as a result of
evaporation of the coolant within the balloon interior is purged
through an exhaust channel in the flexible member in fluid
communication with the balloon interior and with a relief valve
located at a proximal end thereof.
Description
FIELD OF THE DISCLOSED INVENTIONS
[0001] The inventions disclosed herein pertain generally to tissue
ablation systems and instruments, and their use for the treatment
of body tissues; more particularly, the inventions disclosed herein
pertain to cryogenic balloon ablation instruments and their use for
treating body tissue, such as esophageal wall tissue for treating
Barrett's esophagus.
BACKGROUND
[0002] Barrett's esophagus is found in about 10% of patients who
seek medical care for heartburn (gastroesophageal reflux or
"GERD"), and is considered to be a premalignant condition
associated with esophageal cancer. Barrett's esophagus refers to an
abnormal change (metaplasia) in the cells of the lower end of the
esophagus, which is believed to be caused by damage from chronic
stomach acid exposure (reflux esophagitis). Barrett's esophagus is
marked by the presence of columnar epithelia in the lower esophagus
that replaces the normal squamous cell epithelium. The columnar
epithelium is better able to withstand the erosive action of the
gastric secretions; however, this metaplasia confers an increased
cancer risk of the adenocarcinoma type. The metaplastic columnar
cells may be of two types: gastric, which are similar to
metaplastic stomach cells (technically not Barrett's esophagus),
and intestinal, which are similar to metaplastic cells found in the
intestines. A biopsy of the affected area will often contain a
mixture of both cell types. Intestinal-type metaplasia confers a
higher risk of malignancy, and is usually identified by locating
goblet cells in the epithelium.
[0003] Both high and low ("cryogenic") temperature tissue ablation
treatments are currently offered for treating Barrett's esophagus.
As used herein, "tissue ablation" refers to the necrosis,
destruction or killing of tissue cells, which may be accomplished
using a number of different energy delivery modalities for
achieving high or low temperature cell necrosis. By way of one
example, U.S. Pat. No. 7,150,745 discloses a system for ablating
esophageal tissue by positioning an expandable balloon probe in the
area of the esophagus to be treated, the balloon exterior being
plated with a large number of surface electrodes that can be
selectively activated to convey bi-polar radio frequency electrical
energy into the esophageal surface tissue for destroying the
Barrett's cells. By way of further examples, U.S. Pat. Nos.
6,027,499, and 7,025,762 disclose cryogenic ablation systems for
directly spraying esophageal wall tissue with liquid nitrogen.
Cryogenic balloon instruments and systems for (non-ablative)
treatment of blood vessel wall tissue are disclosed and described
in U.S. Pat. No. 6,468,297 and in U.S. Patent Application
Publication No. 20060084962. The foregoing U.S. Pat. Nos.
7,150,745, 6,027,499, 7,025,762 and 7,081,112, and U.S. Patent
Application Publication No. 20060084962 are each incorporated
herein by reference for all that they teach and disclose.
[0004] The objective of these tissue ablation therapies is to
destroy the characteristic Barrett's columnar epithelium layer,
without causing unwanted damage to underlying submucosa tissue or
surrounding healthy tissue. In particular, the columnar epithelium
characteristic of Barrett's esophagus has been reported to reach
lengths of up to 8 cm, and is approximately 500 microns thick.
Disruption of deeper tissues in the muscularis mucosae, located at
a depth of approximately 1000 microns or deeper, can lead to
stricture formation and severe long term complications. On the
other hand, missed or buried "islands" of Barrett's cells can
result if the therapy does not uniformly encompass all affected
tissue areas. Thus, precise control of both the ablation tissue
surface area and "kill depth" are highly desirable.
SUMMARY OF DISCLOSED EMBODIMENTS OF THE INVENTIONS
[0005] In one embodiment of the disclosed inventions, a cryogenic
tissue ablation instrument comprises an elongate flexible body
having a proximal supply port adapted for coupling with a source of
pressurized flowable coolant, e.g., liquid nitrous oxide
(N.sub.2O), and a coolant supply lumen in fluid communication with
the proximal supply port and extending through the elongate body to
a distal portion thereof. A tubular dispersion member is coupled to
or otherwise formed from the distal end portion of the elongate
body, and has an inner lumen that is in fluid communication with
(or an extension of) the elongate body supply lumen. An expandable
balloon is carried on the distal portion of the elongate body, an
interior wall surface of the balloon defining an interior of the
balloon. The balloon is preferably at least semi-compliant and
transparent, although embodiments employing a non-compliant and/or
non-transparent balloon are also contemplated. The dispersion
member at least partially extends into the balloon interior and has
a plurality of coolant dispersion apertures formed therein in fluid
communication with the respective coolant supply lumen and balloon
interior. In particular, the coolant dispersion apertures are sized
and located on the dispersion member so that a pressurized flowable
coolant in the supply lumen will enter the balloon interior through
the dispersion apertures in the form of a liquid spray that
contacts and provides (through rapid evaporation) substantially
uniform cooling of the interior balloon wall surface of a treatment
region of the balloon. Gas formed as a result of the coolant
evaporation is carried through an exhaust passage or lumen in the
elongate body and released through a relief valve at a proximal end
thereof.
[0006] In various embodiments, the treatment region may include
anywhere from only a limited circumferential portion of the balloon
wall up to the entire circumference, and may extend a substantial
portion (e.g., 3-4 cm in embodiments used for treating esophageal
wall tissue) of the axial balloon length. The coolant dispersion
apertures may be offset axially, circumferentially, or both, on the
dispersion member. In one embodiment, a first plurality of
circumferentially spaced apertures is located proximally of a
second plurality of circumferentially spaced apertures on the
dispersion member. The apertures may be substantially uniform in
size, or if needed in order to compensate for pressure losses
within the supply lumen, more proximally located apertures may be
smaller than more distally located ones, with a uniform spray
against the entire (or a sizable portion of the) interior balloon
wall being desirable. In various embodiments, the coolant
dispersion apertures may have shapes such as circular, rectangular
(e.g., slots), or elliptical, although other shapes may be
employed. In one embodiment, instead of a plurality of coolant
dispersion apertures, one or more diffusers and/or deflectors may
be provided along the dispersion member, each configured to direct
a liquid spray of coolant from the supply dispersion member lumen
onto the interior balloon wall surface.
[0007] In embodiments used in treating esophageal wall tissue, the
balloon preferably has a collapsed delivery profile sized for
passage through a working channel of an endoscopic instrument
(e.g., a conventional GI gastroscope) into a human esophagus, and
an expanded treatment profile sized slightly greater than the
interior of the esophagus such that, when the balloon is
transitioned from its collapsed delivery profile to its expanded
treatment profile, an exterior surface of the balloon wall makes
substantially uniform contact with and smoothes out the surrounding
esophageal wall tissue. The balloon is preferably sized and has a
compliance such that, as it transitions from its delivery profile
to its expanded profile, it contacts and smoothes the esophageal
wall tissue. The balloon wall exterior may be made of, or coated
with, a lubricious material to assist in its positioning within,
and smoothing of, the esophageal wall tissue.
[0008] In some embodiments, the balloon wall comprises a first
material, e.g., a polymer, with a second (non-polymer) material
having greater thermal conductivity than the first material
distributed in the balloon in such quantity and configuration so as
to substantially increase the thermal conductivity of the balloon
above the conductivity it would have in the absence of the second
material. By way of non-limiting examples, the second material may
comprise thin metallic strips, fibers, or particles attached to
and/or embedded (e.g., impregnated) in the balloon wall.
[0009] The balloon wall may be made of an optically clear material
to allow for direct visualization through the balloon wall using a
viewing device positioned proximally of the balloon when the
balloon is delivered and expanded in the patient's body. This
allows an attending physician to position the balloon using a
viewing apparatus carried, e.g., in a same endoscopic delivery
device used to deliver the balloon. Hemispherical balloon ends may
be employed to reduce distortion and further facilitate direct
visualization through the balloon wall.
[0010] In embodiments of the disclosed inventions, a medical
treatment system including the cryogenic balloon instrument further
includes a source of pressurized flowable coolant, e.g., a canister
of liquid N.sub.2O, coupled to the proximal supply port of the
instrument, and a controller operatively coupled with the coolant
source so as to controllable release the coolant into the supply
lumen. The system may optionally include one or more temperature
sensors carried on or in the dispersion member and/or balloon wall
in the treatment region of the balloon. The temperature sensors are
operatively coupled to the controller, wherein the controller may
be configured to regulate the release of coolant into the supply
lumen based at least in part on temperature measurements obtained
from the one or more temperature sensors. Additionally or
alternatively, thermochromic material may be carried on and/or in
the balloon wall in the treatment region of the balloon, the
thermochromatic material selected or calibrated to undergo a visual
change in appearance when the balloon wall temperature of the
treatment region reaches a selected tissue ablation temperature. In
this manner, the balloon temperature can be monitored by an
attending physician using a viewing apparatus carried in an
endoscopic delivery device.
[0011] In some embodiments, the elongate body is provided with a
plurality of circumferentially spaced coolant supply lumens, each
in fluid communication with the proximal supply port and extending
through the elongate body to respective corresponding inner lumens
of the dispersion member. In such embodiments, respective
pluralities of coolant dispersion apertures are provided in the
dispersion member such that each plurality of coolant dispersion
apertures is in fluid communication with a respective one of the
coolant supply lumens. The collective apertures are sized and
located on the dispersion member such that a pressurized flowable
coolant in a respective supply (and dispersion member) lumen will
enter the balloon interior in the form of a liquid spray that
contacts and provides (due to rapid evaporation) substantially
uniform cooling of the interior wall surface of a treatment region
of the balloon.
[0012] In one such embodiment, each plurality of coolant dispersion
apertures includes a first aperture having a first aperture size in
communication with a respective coolant supply lumen, and a second
aperture located distally on the dispersion member from the first
aperture in communication with the same coolant supply lumen, the
second aperture having a second aperture size the same or greater
than the first aperture size. In another such embodiment, the
respective dispersion apertures are provided in sets of
circumferentially spaced apertures along the dispersion member
within the balloon interior, each set including respective
apertures in fluid communication with a corresponding one of the
respective coolant supply lumens. In yet another such embodiment,
the portion of the dispersion member extending into the balloon
interior is itself an expandable body, with the respective coolant
dispersion apertures located on an exterior surface of this inner
expandable body.
[0013] In one embodiment, the treatment region is a distal facing
portion of the balloon wall, the coolant dispersion aperture(s)
being located relative to the balloon such that a pressurized
flowable coolant in the supply lumen is directed axially in the
form of a liquid spray applied against the interior surface of the
distal balloon wall portion. In another embodiment, the energy
delivery portion is a side (i.e., lateral relative to the
longitudinal axis of the balloon) facing portion of the balloon
wall, the dispersion aperture(s) being located relative to the
balloon such that a pressurized flowable coolant in the supply
lumen is directed radially in the form of a liquid spray applied
against the interior surface of the respective balloon side wall
portion.
[0014] In one embodiment, the balloon is a multi-lobe balloon
having a plurality of isolated, separately inflatable balloon
chambers, wherein each balloon chamber may be selectively placed in
fluid communication with a respective coolant supply lumen
extending through the elongate body. Alternatively or additionally,
the respective balloon chambers may also be selectively placed in
fluid communication with independent fluid or gas inflation sources
(other than the coolant) through further respective lumens
extending through the elongate body. The dispersion member extends
through a central region of the multi-lobe balloon, wherein the
coolant supply lumens are selectively placed in fluid communication
with a respective one of the interior balloon chambers via a
respective plurality of coolant dispersion apertures formed in the
dispersion member. The respective dispersion apertures are sized
and located on the dispersion member such that a pressurized
flowable coolant in any of the supply lumens will enter the
respective balloon chamber in the form of a liquid spray that
contacts and provides cooling of an interior wall surface of the
respective chamber. In a treatment system including a multi-lobe
balloon embodiment further includes a source of pressurized
flowable coolant fluidly coupled to the respective instrument
supply ports, and a controller operatively coupled with the source
of pressurized flowable coolant. The controller is configured to
selectively, independently and controllably release the coolant
into one or more of the supply lumens. Gas formed as a result of
coolant evaporation in any of the respective balloon lobes may be
carried through a common (or separate) exhaust lumen in the
elongate body and released though a respective relief valve located
at a proximal end thereof.
[0015] In still another embodiment, a method is provided for
ablating wall tissue using a cryogenic balloon instrument, the
instrument comprising an elongate flexible member carrying an
expandable balloon on a distal end thereof, the balloon having a
collapsed delivery shape and an inflated treatment shape, the
method including positioning the cryogenic balloon while in its
collapsed delivery shape through a working channel of an endoscopic
instrument to a desired location in a patient's body (e.g.,
esophagus) to be treated; inflating the cryogenic balloon so that
an outer wall surface thereof makes substantially uniform contact
with, and smoothes the wall tissue to be treated; and delivering a
pressurized flowable coolant from a source external to the patient
through a supply lumen in the elongate body and out one or more
dispersion apertures in fluid communication with the supply lumen,
the one or more dispersion apertures sized and located such that
the pressurized flowable coolant enters the balloon interior in the
form of a liquid spray that contacts and provides (through rapid
evaporation) substantially uniform cooling of the interior balloon
wall surface of a treatment region of the balloon. Gas formed as a
result of evaporation of the coolant within the balloon interior
may be purged through an exhaust lumen extending from the balloon
interior to a relief valve located at a proximal end of the
elongate body.
[0016] Other and further embodiments, aspects and features of the
disclosed embodiments will become apparent to those skilled in the
art in view of the accompanying figures and the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The drawings illustrate the design and utility of
embodiments of the disclosed inventions, in which similar elements
are referred to by common reference numerals, and in which:
[0018] FIG. 1A is a simplified schematic illustration of a system
used for treating esophageal tissue using a cryogenic balloon
instrument constructed and positioned in the esophagus according to
one embodiment.
[0019] FIG. 1B is a simplified, partially cut-away perspective view
of a first embodiment of a cryogenic balloon carried on an elongate
instrument body for use in the system of FIG. 1A.
[0020] FIG. 1C is a simplified schematic illustration of a
controller for use in the system of FIG. 1A.
[0021] FIG. 2 is a simplified, partially cut-away perspective view
of a tubular dispersion member connected to a distal end portion of
a cryogenic balloon instrument used in the system of FIG. 1A.
[0022] FIGS. 3 and 3A depict one embodiment of a tubular dispersion
member that extends axially through the cryogenic balloon in FIG.
1B, including a first configuration of coolant dispersion apertures
for introducing a pressurized coolant into the balloon
interior.
[0023] FIGS. 4 and 4A depict another embodiment of the tubular
dispersion member that extends axially through the cryogenic
balloon in FIG. 1B, including an alternate configuration of coolant
dispersion apertures for introducing a pressurized coolant into the
balloon interior.
[0024] FIG. 5 is a simplified, partially cut-away perspective view
of an alternate cryogenic balloon embodiment for use in the system
of FIG. 1A, in which the coolant dispersion apertures are formed
out of flaps cut into the tubular dispersion member body, with the
most distal edge of the flap remaining attached to the dispersion
member body, and the proximal end depressed into the interior
dispersion member lumen to form a directional ramp for dispersing
coolant into the balloon interior.
[0025] FIG. 5A is a close-in side view of a fluid dispersion
aperture ramp in the embodiment of FIG. 5.
[0026] FIG. 6 is a simplified, partially cut-away perspective view
of another alternate cryogenic balloon embodiment for use in the
system of FIG. 1A, in which a centrally located diffuser and
reflector combination are used to direct coolant from the
dispersion member lumen against the balloon wall.
[0027] FIG. 6A is a close up of an embodiment of a
diffuser/deflector assembly for use in the dispersion member
depicted in FIG. 6.
[0028] FIGS. 7-8 are perspective views of alternate embodiments of
a balloon body that may be used in combination with any of the
cryogenic instrument embodiments disclosed herein, in which thin
strips or fibers of metallic material having relatively high
thermal conductivity are attached to, or embedded in, the balloon
wall.
[0029] FIGS. 9-10 are simplified, partially cut-away perspective
views of still further respective alternate cryogenic balloon
embodiments for use in the system of FIG. 1A, in which a plurality
of circumferentially spaced coolant supply lumens are provided in
the elongate instrument body and dispersion member.
[0030] FIGS. 11A-B are distal end perspective views of an
embodiment of a cryogenic balloon body shown in a collapsed
configuration when initially positioned within an esophagus (FIG.
11A), and in an expanded treatment configuration (FIG. 11B) after
having smoothed out the esophageal wall tissue to be treated.
[0031] FIG. 12 is a simplified, partially cut-away perspective view
of yet another cryogenic balloon embodiment for use in the system
of FIG. 1A, in which a plurality of temperature sensors are carried
on or in the balloon wall.
[0032] FIG. 13 is a simplified, partially cut-away perspective view
of still another cryogenic balloon embodiment for use in the system
of FIG. 1A, in which thermochromic material is carried on and/or in
the balloon wall,
[0033] FIG. 14-17 are simplified, partially cut-away perspective
views of still further cryogenic balloon embodiments for use in the
system of FIG. 1A.
[0034] FIG. 18 is an illustrative plot of computer simulation of
tissue temperature-versus-time at varying tissue depths of a human
esophagus when contacted by a balloon wall having a temperature of
-40.degree. C.
[0035] FIG. 19 is a time-versus-temperature plot of temperatures
measured using thermocouples positioned to monitor temperature at
multiple axial and circumferential locations on the outer surface
of a prototype cryogenic balloon constructed in accordance with one
embodiment of the disclosed inventions, demonstrating that
temperatures along a 4 cm length of the balloon were substantially
uniform during cooling of the balloon wall.
[0036] FIG. 20 is a simplified side view of a tubular dispersion
member that may be employed in various embodiments of a
cryo-ablative balloon instruments used in the system of FIG.
1A.
[0037] FIGS. 20A-B are sectional views taken along lines A-A and
B-B, and FIGS. 20C-D are exploded views taken along lines C-C, and
D-D, respectively, in FIG. 20.
DETAILED DESCRIPTION
[0038] Embodiments of the inventions disclosed and described herein
are directed to cryogenic balloon systems and their use for
treating body tissue, in particular but not limited to esophageal
wall tissue. By way of non-limiting examples, embodiments of the
invention include elongate flexible instrument carrying cryogenic
balloons designed for introduction through a working channel of a
standard GI gastroscope into a patient's esophagus, and then
expanded to contact and smooth the esophagus wall, thereafter
producing a controlled and substantially uniform "cold zone" that
will kill characteristic Barrett's esophagus columnar epithelium
cells in the esophageal wall tissue, without unduly harming tissues
in the muscularis mucosae or deeper. The following detailed
description is directed to such embodiments used for treating
esophageal tissue. However, such embodiments are disclosed and
described by way of illustration, and not limitation, and other and
different balloon embodiments configured for treating body tissue
regions other than the esophagus are also contemplated herein.
[0039] For purposes of illustration, and with reference generally
to exemplary embodiments of the disclosed inventions, ablative
cooling for destroying the columnar epithelium cells is achieved by
evaporation of a flowable coolant, e.g., liquid nitrous oxide
(N.sub.2O), sprayed in a substantially uniform manner onto an
interior wall surface of a dilation-type balloon positioned in the
esophagus being treated. The balloon may be compliant,
semi-compliant, non-compliant, depending on the particular
embodiment, but is preferably at least semi-compliant in
embodiments used for treating esophageal wall tissue. The coolant
is released from a high pressure cylinder into one or more confined
supply lumens of a relatively small diameter elongate flexible
instrument, and driven down a pressure gradient to a distal portion
of the instrument on which the cryogenic balloon is carried.
[0040] Within the balloon, the coolant is allowed to escape through
one or more, relatively small coolant dispersion apertures in a
dispersion member coupled to or otherwise formed from a distal end
portion of the elongate instrument body, the dispersion apertures
in fluid communication with the respective supply lumen(s) and
balloon interior. The supply line pressure and aperture sizing are
configured such that the coolant sprays against an inside surface
of the balloon wall and evaporates rapidly, thereby creating a
corresponding rapid cooling of the balloon wall and surrounding
environment within the balloon interior.
[0041] The balloon may be initially inflated by releasing a
controlled pulse of coolant, and the supply line pressure is
thereafter maintained at a level close to the source pressure,
e.g., approximately 800 psi or higher, in order to maintain the
coolant in liquid form. It will be appreciated that the system
pressure will undergo a significant drop across the coolant
apertures (i.e., between the supply lumen(s) and the balloon
interior), with a balloon and exhaust lumen pressure preferably
maintained at less than 100 psi, and preferably in a range of 5-50
psi. The coolant dispersion aperture(s) are preferably sized so as
to preferably create a continuous spray (or mist) of coolant there
through. The coolant dispersion aperture(s) are located on the
dispersion member so that a substantially uniform temperature
distribution along a treatment region of the balloon surface is
achieved. The treatment region may include only a portion or the
entire circumference of the balloon. Gas formed as a result of
coolant evaporation is carried through an exhaust lumen in fluid
communication with the balloon interior and extending through the
elongate body, wherein the gas is released through a relief valve
located at a proximal end of the instrument, the relief valve
pressure setting selected to maintain a desired balloon inflation
pressure, taking into account losses incurred through the exhaust
lumen.
[0042] The volume of liquid coolant and the evaporation pressure
are controlled to produce an exterior balloon treatment surface
temperature reaching as low as -80.degree. C. to -90.degree. C.,
although more preferably the balloon wall will be cooled within an
operating range of -30.degree. C. to -40.degree. C. for a time
period of 10-20 seconds, which is believe sufficient for achieving
a uniform tissue kill depth, e.g., 500 microns, sufficient to
destroy Barrett's cells when treating the esophagus, without
causing harm to the deeper submucosal tissue. Computer simulations
were performed to calculate the subsurface temperature profile in
esophageal tissue placed in thermal contact with an 18 mm diameter
cryogenic balloon catheter with respective balloon wall
temperatures of -20.degree. C., -40.degree. C., -60.degree. C. and
-80.degree. C. A plot of tissue-temperature-versus-time at varying
tissue depths based on such computer simulations is shown in FIG.
18. These simulations show that temperatures between approximately
-30.degree. C. and -20.degree. C. are expected at tissue depths
between 500 and 1000 microns from the surface after 30 seconds
surface contact time using a balloon having a -40.degree. C. wall
temperature. It will be appreciated by those skilled in the art
that the actual balloon surface temperature and time parameters may
be varied, depending on patient parameters and the tissue being
treated, among other factors.
[0043] In an exemplary embodiment, the cryogenic balloon has a
delivery configuration designed to pass through the working channel
of an upper GI gastroscope and an expanded profile sized to make
solid uniform contact with, and smooth the esophageal wall tissue
to be treated. In various embodiments, the folded balloon
configuration has a profile (or diameter) less than 3.7 mm,
preferably less than 2.8 mm, and more preferably less than or equal
to 2.5 mm. In particular, a range of balloons varying from 18 mm to
34 mm in diameter may be employed to cover the full size range of
the human esophagus, with appropriate sizing to assure good contact
between the balloon and esophageal wall tissue. The length of the
active treatment region of the balloon may vary, but is preferably
between 3 and 4 cm for treatment of human esophageal wall tissue.
The treatment region may include the entire circumference of the
balloon, or may be focused to a more limited energy delivery
balloon wall surface. In various embodiments, the total working
length of the elongate instrument will be greater than 120 cm and
preferably equal to or greater than 180 cm to allow for passage
through standard endoscopes. It will be appreciated that the
balloon may be provided in different (expanded treatment)
dimensions, depending in part on compliancy, in order to treat a
full range of human esophagus sizes.
[0044] To initiate treatment, the distal portion of the elongate
instrument and balloon are advanced through the working channel of
the gastroscope, until the balloon is extended beyond the open tip
and positioned in a targeted area of the patient's esophagus. The
balloon is then expanded using an initial pulse of coolant released
from the source through the supply lumen(s) into the balloon. This
initial inflation pulse is preferably sufficient to inflate the
balloon to its full inflation pressure to contact and smooth the
esophagus wall, without also causing significant cooling of the
balloon wall. Once the balloon is inflated and its position
relative to the tissue being treated is confirmed, substantial and
rapid cooling of the balloon wall is initiated by the controlled
release and evaporation of a liquid coolant against the inner wall
of the balloon, until the surface temperature in the treatment
region of the balloon is reaches a desired tissue ablation
temperature. The balloon is then maintained at this temperature (or
within a close range thereto) for a specified treatment period,
e.g., in a temperature range of -30.degree. C. to -40.degree. C.
for a time period of 10-20 seconds, for killing all cells in the
contacting esophageal tissue up to a depth of about 500 microns,
without harming or disrupting cells deeper than about 1000
microns.
[0045] FIGS. 1A-C depict an exemplary embodiment of a cryogenic
balloon system 20 used for treating a patient's esophagus 22. The
system 20 generally includes a cryogenic tissue ablation instrument
21 comprising an elongate flexible body 28 having a proximal supply
port (not shown) adapted for coupling with a source of pressurized
flowable coolant 39 (e.g., a canister of liquid N.sub.2O). The
elongate body 28 includes an internal supply lumen 43 in fluid
communication with the proximal supply port and extending through
the elongate body 28 to a distal portion (29) thereof. An
expandable balloon 30 is carried on the distal portion 29 of the
elongate body 28, the balloon 30 having a wall 31, with an interior
surface 24 of the wall defining an interior 35 of the balloon 30.
The balloon 30 and instrument distal portion 29 are preferably
sized for introduction through a working channel of gastroscope 26
into the patient's esophagus 22.
[0046] The balloon 30 may be constructed of a compliant or
semi-compliant material in order to improve contact with the wall
tissue of the esophagus 22, and minimize a number of discrete
balloon sizes needed to treat a full range of human esophagi. The
balloon wall 31 is preferably constructed of adequately transparent
material that will allow for direct visualization through the
balloon wall 31 using a viewing device positioned proximally of the
balloon (e.g., a viewing lens of the gastroscope) when the balloon
is delivered and expanded in the patient's esophagus 22. This
allows an attending physician to position the balloon 30 in the
esophagus 22 using a viewing apparatus carried in the endoscopic
delivery device. Hemispherical balloon ends may reduce distortion
and further facilitate direct visualization through the balloon
wall.
[0047] A tubular dispersion member 49 is coupled to or otherwise
formed from the distal portion 29 of the elongate body 28, and
extends through the balloon interior 35 to a distal balloon end
anchor 36. The dispersion member 49 has an interior lumen 43' in
fluid communication with or otherwise comprising a distal portion
of the supply lumen 43, with a plurality of coolant dispersion
apertures 37 formed (e.g., laser drilled) in the dispersion member
in fluid communication with the respective supply lumen 43 and
balloon interior 35. The coolant dispersion apertures 37 are sized
and located along the dispersion member 49 such that pressurized
coolant in the supply lumen 43 will enter the balloon interior 35
through the respective apertures 37 in the form of a liquid spray
38 that contacts and provides (due to rapid evaporation of the
liquid coolant) substantially uniform cooling of an active
treatment length or region 50 of the interior balloon wall surface
24. The distal end of the dispersion tube 49 is preferably sealed
to force coolant flow through the respective coolant apertures
37.
[0048] The system includes a controller 34 operatively coupled with
the source of pressurized coolant so as to controllable release the
coolant into the supply lumen 43. The controller 34 may be the same
or substantially similar to that used for the PolarCath.TM.
vascular cryogenic balloon system distributed by Boston Scientific
Corporation, Natick Mass. (www.bsci.com), which is disclosed and
described in the above-incorporated U.S. Patent Application
Publication No. 20060084962. In particular, the controller 34 is
programmed to controllably release the liquid coolant into the
respective supply lumen 43 and balloon interior 35 to maintain the
balloon wall temperature at a desired operating temperature for a
specified time period.
[0049] Referring briefly to FIG. 12, the system 20 may optionally
include one or more temperature sensors 63 carried in the
dispersion tube lumen 43' and/or in the balloon wall 31 in the
treatment region 50 of the balloon (referred to as 30A), which are
operatively coupled to the controller 34 via wires 69 that extend
through the elongate body 28. In this configuration, the controller
34 may regulate release of the coolant into the supply lumen 43
based at least in part on input from the one or more temperature
sensors 63. In some such embodiments, the measured temperature is
monitored as a safety override, wherein the flow of coolant is
stopped if the temperature drops below (or rises above) a
predetermined threshold. In other embodiments, the measured
temperature may be used for controlling the rate of release of the
coolant for more precisely regulating the temperature a desired
operating point.
[0050] Referring briefly to FIG. 13, in an alternative embodiment,
thermochromic material 57 may be carried on and/or in the balloon
wall 31 in the treatment region of the balloon (referred to as
30B), the thermochromatic material 57 selected to undergo a visual
change in appearance when the temperature of the balloon wall 31
passes a selected threshold temperature (e.g., -40.degree. C.). In
this manner, the temperature of the active balloon region 50 may be
monitored visually by an attending physician using a viewing
apparatus carried in the gastroscope 26. Notably, in the
illustrated balloon 30B, the thermochromatic material 57 is placed
at the respective edges of the treatment region 50, although it may
be desirable to place the material in other locations, or even to
embed the material 57 throughout the balloon wall 31, so that the
balloon 30B as a whole changes appearance once the temperature
threshold is reached.
[0051] Returning to the illustrated balloon 30 of FIG. 1B, the
coolant dispersion apertures 37 are sized and located along the
dispersion member 49 within the balloon interior 35 such that an
entire circumference of the active region 50 undergoes
substantially uniform cooling. In turn, the balloon treatment
region 50 imparts a substantially uniform temperature gradient on
the contacted tissue in the esophagus 22. The temperature of the
balloon wall 31 in the active treatment region 50 may be regulated
by the controller 34, by regulating the output flow of the coolant,
so that the system 20 is able to deliver controlled cryogenic
tissue destruction of the Barrett's esophagus columnar epithelium
cells in the esophageal wall tissue, without unduly harming deeper
tissues, such as the muscularis mucosae or submucosae.
[0052] The coolant dispersion apertures 37 can have a number of
different shapes, such as circular, rectangular (e.g., a slot), or
elliptical. In the case where multiple coolant dispersion apertures
37 are provided, they may be axially offset, circumferentially
offset, or both, along the dispersion member 49. In the case of
axially offset dispersion apertures, the more proximally located
aperture(s) may optionally be made smaller than the more distally
located apertures(s) in order to compensate for pressure losses
within the coolant supply lumen 43. However, it is believed that a
substantially uniform outflow spray against the interior balloon
wall 24 can be achieved with substantially uniform sized apertures
when they are relatively small, e.g., on the order of 0.001 to
0.008 inches in diameter, and approximately 0.002 inches in
diameter in one embodiment.
[0053] By way of example, in the illustrated balloon embodiment 30
in FIG. 1B, the coolant dispersion apertures 37 include five,
axially offset groupings, or "sets" of apertures 37, each set
including a plurality of circumferentially offset apertures. As
seen in FIGS. 3 and 3A, in one embodiment, each set of
circumferential offset apertures 37 includes eight apertures
approximately evenly spaced about the circumference of the
dispersion member 49, i.e., with each aperture 37 being offset
approximately 45.degree. from adjacent apertures in the same set
(best seen in FIG. 3A). Although the respective sets of
circumferentially offset apertures 37 are longitudinally (axially)
offset (i.e., displaced) along the length of the dispersion member
49, the apertures 37 within an individual set remain aligned in a
same relative rotational position about the circumference of the
elongate body 28, as illustrated by dashed lines 46.
[0054] With reference to FIGS. 4 and 4A, in an alternative
embodiment for use in the cryogenic balloon system 20 of FIG. 1,
adjacent sets of coolant dispersion apertures 37 provided on the
dispersion member (designated as 49') are both axially and
circumferentially offset from one another. In particular, each set
of circumferential offset apertures 37 provided in the dispersion
member 49' includes eight apertures substantially evenly spaced
about the circumference of the dispersion member 49', each aperture
37 of an individual set being offset approximately 45.degree. from
adjacent apertures in the same set (best seen in FIG. 4A), with the
respective apertures 37 in adjacent sets being collectively offset
(rotationally) from one another approximately 22.5.degree. about
the circumference, as indicated by the dashed lines 46'.
[0055] In one embodiment of the distal end assembly (shown in FIG.
2 without the balloon wall for ease in illustration), the elongate
body 28 carries an inner tubular member 86 that defines the supply
lumen 43, along with a thermocouple 63 within an interior lumen 73,
wherein the remaining annular space in the lumen 73 functions as a
gas exhaust lumen. A proximal end of the dispersion member 49 has
an interior lumen 43' that receives and surrounds the tubular
member 86 and thermocouple 63, with the inner wall of the
dispersion member 49 forming a fluid tight bond 79 around the
respective tubular member 86 and thermocouple 63, with the supply
lumen 43 in fluid communication with an interior lumen 43' of the
dispersion member 49. A central stiffening member 83 is provided
through the axial center of the dispersion member 49 for structural
support (in particular, to resist axial compression). A fluid tight
seal 84 is in provided at the distal end of the dispersion member
49, sealing off lumen 43' to force fluid flow through the fluid
apertures (not shown in FIG. 2).
[0056] Gas formed as a result of coolant evaporation in the balloon
interior (not shown in FIG. 2) is carried back through the exhaust
lumen 73 in the elongate body 28, and released through a relief
valve (not shown) at a proximal end thereof. In particular, the
closed system including the exhaust lumen 73 allows for passage of
the (very cold) exhaust gas out of the patient's body, without
allowing the gas to directly contact and potentially harm the
healthy esophageal, throat and mouth tissue. This is a significant
improvement over prior art systems that spray the coolant fluid
directly on the esophagus wall. FIG. 20 is a simplified side view
of one embodiment of a fluid dispersion tube 131 having a series of
axially displaced fluid dispersion apertures 137, which may be
employed in various embodiments of cryo-ablative balloon
instruments used in the system of FIG. 1A. FIGS. 20A-B are
sectional views taken along lines A-A and B-B, and FIGS. 20C-D are
exploded views taken along respective lines C-C and D-D,
respectively, illustrating the formation and dimensions of the
fluid dispersion apertures 137 in the fluid dispersion tube 131 in
FIG. 20. Again, a fluid tight seal (not shown) is preferably
provided at the distal end of the dispersion tube 131 to force
fluid flow through the respective fluid apertures 137.
[0057] A variety of fluid dispersion member designs are envisioned
and contemplated for use in embodiments of the disclosed
inventions. FIGS. 5 and 5A depict an alternate cryogenic balloon
130 that may be carried distally on the elongate instrument body 28
of the instrument of system 20. As with balloon 30, balloon 130 may
be constructed of a compliant or semi-compliant material, and
includes a wall 131, with an interior surface 124 of the wall 131
defining an interior 135 of the balloon 130. A dispersion tube 149
is coupled to (or alternatively formed from) a distal end portion
of elongate body 28, extending through the balloon interior 135 to
a distal balloon end anchor 136. The dispersion tube 149 has a
plurality of coolant dispersion apertures 137 in fluid
communication with the respective supply lumen 43 and balloon
interior 135, wherein the coolant dispersion apertures 137 are
sized and located along the dispersion tube 149 such that
pressurized coolant 138 in the supply lumen 43 (and dispersion tube
lumen 143') will enter the balloon interior 135 in the form of a
liquid spray 138 that contacts and provides (due to rapid
evaporation of the liquid coolant) substantially uniform cooling of
an active treatment length or region 150 of the interior balloon
wall surface 124.
[0058] More particularly, the axially and circumferentially spaced
coolant dispersion apertures 137 in the embodiment of FIG. 5 are
formed from rectangular flaps 145 cut into the dispersion tube 149.
As best seen in FIG. 5A, the most distal edge 152 of each flap 145
remains attached to the dispersion tube 149, with the proximal flap
end 155 depressed into the supply lumen 43 to form a directional
ramp for dispersing coolant 138 flowing in the supply lumen into
the balloon interior 135. The proximal flap ends 155 may optionally
be bonded to an internal mandrel (not shown) positioned within the
inner lumen 143' to add stability.
[0059] FIG. 6 depicts another alternate cryogenic balloon 230 that
may be carried distally on the elongate instrument body 28 of
system 20. As with balloons 30 and 130, balloon 230 may be
constructed of a compliant or semi-compliant material, and includes
a wall 231, with an interior surface 224 of the wall 231 defining
an interior 235 of the balloon 230. A dispersion tube 249 coupled
to (or alternatively is formed from) a distal end portion of
elongate body 28, and extends through the balloon interior 235 to a
distal balloon end anchor 236. Instead of a plurality of coolant
dispersion apertures as employed in the previously described
embodiments, one or more diffusers 242 are provided on the
dispersion tube 249, each diffuser 242 configured to direct a
liquid spray of coolant 238 from the dispersion tube lumen onto the
interior balloon wall surface (as indicated by reference number
238d).
[0060] The embodiment of FIG. 6 is also equipped with one or more
(optional) deflectors 258 provided on the dispersion tube 249, each
deflector 258 located adjacent distally of a respective diffuser
242. The deflector(s) 258 are configured to deflect at least a
portion of the fluid coolant spray (as indicated by reference
number 238p) originally directed (or allowed to pass by) by a
respective diffuser 242, with the collective result of the
arrangement of distally directed diffusers 242 and proximally
directed deflectors 258 being a substantially uniform spraying of
coolant on the interior balloon wall 224 within an active treatment
region 250 of the balloon 230. FIG. 6A depicts one embodiment of a
respective diffuser/deflector pair 242/258.
[0061] The cryogenic balloons (30, 130, 230) disclosed and
described herein are preferably made from a flexible, at least
semi-compliant polymer, such as polyether block amide (Pebax.RTM.)
or nylon as is well-known in the art, providing a reasonable and
serviceable degree of thermal conductivity in the balloon wall in
the active treatment region. However, it may be desirable to
incorporate materials having relatively high thermal conductivity
in the balloon wall to increase uniformity in balloon wall
temperature within the active treatment region of the balloon. On
the other hand, such increased thermal conductivity should not come
at the expense of loss of adequate compliance or, in some
embodiments, balloon wall transparency. Thus, it may be desirable
to form a cryogenic balloon for use in the system 20 of FIG. 1 out
of a composite material structure, including a first, at least
semi-compliant polymer material, and a second material having
relatively high thermal transfer properties. Representative high
thermal conductivity materials may include carbon nano-tubes,
graphite, ultra-thin metal fibers, including silver, gold,
stainless steel, nitinol, diamond like carbon coatings, pyrolytic
carbon, and boron nitride coatings. The materials may be attached
to a surface (interior or exterior) of the balloon wall, e.g.,
using known vapor deposition, plating or uniform coating processes,
or may be embedded or impregnated within the balloon wall.
[0062] By way of example, FIG. 7 depicts one embodiment of a
composite material balloon 330 for use (in combination) with any of
the cryogenic balloon embodiments disclosed herein, in which a
plurality of axially spaced thin metallic strips or fibers 332 are
attached to and/or embedded in a polymer balloon wall 331 to
increase the overall thermal conductivity of the balloon 330. The
strips or fibers 332 are preferably thin and spaced apart
sufficiently such that balloon compliance and/or transparency
remain adequate. By way of further example, FIG. 8 depicts another
embodiment of a composite material balloon 430 for use (in
combination) with any of the cryogenic balloon embodiments
disclosed herein, in which a plurality of circumferentially spaced
thin metallic strips or fibers 432 are attached to and/or embedded
in a polymer balloon wall 431 to increase the overall thermal
conductivity of the balloon 430. Again, the metallic strips or
fibers 432 are preferably thin and spaced apart sufficiently such
that balloon compliance and/or transparency remain adequate.
[0063] Referring to FIG. 9, in accordance with another embodiment
of the disclosed inventions, a cryogenic tissue ablation elongate
instrument 528 may be used in a modified version of system 20, and
has a proximal supply port (not shown) adapted for coupling with
the source of pressurized flowable coolant 39 (e.g., liquid
N.sub.2O), and a dispersion member 549 coupled to (or alternatively
formed out of) a distal end portion of the elongate instrument 528.
The elongate body 528 has a plurality of circumferentially spaced
coolant supply lumens 543, each in fluid communication with the
proximal supply port (not shown), and each extending through the
elongate body 528, where they are directly fluidly coupled, or
otherwise comprise corresponding respective interior lumens 543' of
the dispersion member 549. An expandable balloon 530 is carried on
the distal end portion of the elongate body 528, the balloon 530
having a wall 531 with an interior surface 524 defining an interior
535 of the balloon. The dispersion member 549 extends into the
balloon interior 535, and has respective pluralities of coolant
dispersion apertures 537 formed therein, each plurality of coolant
dispersion apertures 537 in fluid communication with a respective
one of the coolant supply (and dispersion member) lumens 543 (and
543'). The collective apertures 537 are sized and located on the
dispersion member 549 such that a pressurized flowable coolant in
the respective supply and dispersion member lumens 543/543' will
enter the balloon interior 535 through the respective apertures 537
in the form of a liquid spray 538 that contacts and provides (due
to rapid evaporation) substantially uniform cooling of the interior
wall surface 524 of a treatment region 550 of the balloon.
[0064] Each plurality of coolant dispersion apertures 537
preferably includes a first aperture having a first aperture size
in communication with a respective coolant supply lumen 543, and a
second aperture located distally on the elongate member 529 from
the first aperture in communication with the same respective
coolant supply lumen 543, the second aperture having a second
aperture size the same or greater than the first aperture size, as
needed to account for pressure losses in the respective supply
lumen 543, while maintaining substantially uniform output spray
538. In the illustrated embodiment of FIG. 9, the respective
dispersion apertures 537 are provided in sets of circumferentially
spaced apertures along the dispersion member 549 within the balloon
interior 535, each set including respective apertures 537 in fluid
communication with a corresponding one of the respective coolant
supply lumens 543.
[0065] FIG. 10 shows a variation of the embodiment of FIG. 9, in
which the portion of the dispersion member (designated 549')
extending into the balloon interior (designated 535') is itself an
expandable body, with the respective coolant dispersion apertures
537 located on an exterior surface 561 of the "inner" expandable
body 549'.
[0066] As mentioned previously, the cryogenic balloon embodiments
disclosed and described herein are preferably able to be positioned
in an esophagus to be treated through a standard working channel of
a GI gastroscope. By way of illustration, FIGS. 11A-B depict a
perspective view of a cryogenic balloon body 730 that may be
employed in combination any of the embodiments described herein for
use in system 20. The balloon body 730 is depicted in both a
collapsed delivery configuration 732 (FIG. 11A) and an expanded
treatment configuration 738 (FIG. 11B). The collapsed delivery
configuration 732 is shown positioned within an esophagus 722 in
its relaxed state and which is characterized by the esophagus wall
735 being collapsed in the radial direction and gathered into
longitudinally oriented folds 736 around the collapsed balloon body
732. Upon expansion of the balloon 730 to its treatment
configuration 738, the esophagus wall 735 is expanded and smoothed
to configuration 740 (indicated by arrows 745 in FIG. 11B).
[0067] The profile of the expanded treatment balloon configuration
738 is preferably slightly greater than the interior of the
esophagus 722 such that, when the balloon 730 is transitioned from
its collapsed delivery profile 732 to its expanded profile 738, an
exterior wall surface of the balloon contacts and smoothes the
esophageal wall tissue, providing for more uniform thermal contact
with the balloon wall, and as a consequence, more uniform cooling
of the esophageal tissue, resulting in a more uniform depth of
tissue ablation from the treatment. At the same time, the cryogenic
balloon 730 preferably has a compliance such that, as it
transitions from its collapsed delivery profile 732 to its expanded
treatment profile 738, the force of the esophageal wall tissue
exerted back on the balloon wall causes the balloon 730 to assume a
more elongated shape than it has in the absence of such force. The
exterior wall surface of the balloon 730 is preferably made of or
coated with a lubricious material to facilitate its positioning and
smoothing of the esophageal wall tissue. Built-in tensioning
elements (not shown) may optionally be added to reduce the profile
of the balloon 30, and ease in its withdrawal back through the
working channel of the gastroscope after treatment of the esophagus
722 is completed.
[0068] In some circumstances, it may be advantageous for ablating a
more localized area of the esophageal tissue wall. Instruments
designed more specifically for this purpose are shown in FIGS.
14-16. These instruments have an identical or substantially similar
proximal portion as instrument 21 in system 20, i.e., controller 34
operatively coupled with a canister of pressurized coolant 39), and
are similarly operated and controlled. Referring to FIG. 14, one
such cryogenic tissue ablation instrument 1020 includes an elongate
flexible body having a proximal supply port (not shown) adapted for
coupling with a source of a pressurized flowable coolant, and a
coolant supply lumen 1043 in fluid communication with the proximal
supply port and extending through the elongate body to a distal end
portion thereof. An expandable balloon 1030 is carried on the
distal end of the elongate body, the balloon 1030 having a
(preferably at least semi-compliant) wall 1031, wherein an interior
surface 1024 of the wall 1031 defines an interior 1035 of the
balloon 1030.
[0069] A dispersion member 1049 coupled to or otherwise formed from
a distal end portion of the elongate body extends within the
balloon interior 1035 and has a plurality of coolant dispersion
apertures in fluid communication with the supply lumen 1043, the
dispersion apertures being sized and positioned in the dispersion
member 1049 with respect to the balloon wall 1031, such that a
pressurized flowable coolant in the supply lumen 1043 will enter
the balloon interior 1035 through the apertures 1037 in the form of
a liquid spray 1038 that contacts and provides (due to rapid
evaporation) substantially uniform cooling of an energy delivery
portion 1039 of the balloon wall 1031. Notably, the energy delivery
portion of the balloon wall 1039 is side facing, with the coolant
dispersion apertures 1037 positioned relative to the balloon wall
portion 1039 so that the coolant spray 1038 is directed radially
relative to the longitudinal axis of the elongate instrument body.
In order to avoid unwanted collateral tissue cooling, those
portions of the balloon wall 1031 that are not part of the energy
delivery portion 1039 are coated with an insulation layer 1050.
[0070] FIGS. 15A-B depict an alternate embodiment of a "side
firing" cryogenic balloon instrument 1120, which includes an
elongate flexible body 1128 having a proximal supply port (not
shown) adapted for coupling with a source of a pressurized flowable
coolant, a distal end portion 1129 sized for introduction into a
human esophagus, and a coolant supply lumen 1143 in fluid
communication with the proximal supply port and extending through
the elongate body 1128 to the distal end portion 1129. An
expandable balloon 1130 is carried on the distal end portion 1129
of the elongate body 1128, the balloon 1130 having a (preferably at
least semi-compliant) wall 1131, wherein an interior surface 1124
of the wall 1131 defines an interior 1135 of the balloon 1130.
[0071] The distal end portion 1129 of the elongate body 1128 is
attached to the balloon wall 1131 (rather than extending through
the balloon interior as in previous embodiments), and has a
plurality of coolant dispersion apertures 1137 in fluid
communication with the respective supply lumen 1143 and balloon
interior 1135. The dispersion apertures are sized and positioned on
the elongate body 1129 with respect to the balloon wall 1131, such
that a pressurized flowable coolant in the supply lumen 1143 will
enter the balloon interior 1135 through the apertures 1137 in the
form of a liquid spray 1138 that contacts and provides (due to
rapid evaporation) substantially uniform cooling of an energy
delivery portion 1139 of the balloon wall 1131. As with instrument
1020, the energy delivery portion 1139 of the balloon wall 1131 of
instrument 1120 is side facing, with the coolant dispersion
apertures 1137 positioned relative to the energy delivery balloon
wall portion 1139 so that the coolant spray 1138 is directed
radially relative to the longitudinal axis of the elongate
instrument body 1128.
[0072] FIG. 16 depicts a further embodiment of a more localized
cryogenic balloon instrument 1220, which includes an elongate
flexible body 1228 having a proximal supply port (not shown)
adapted for coupling with a source of a pressurized flowable
coolant, a distal end portion sized for introduction into a human
esophagus, and a coolant supply lumen 1243 in fluid communication
with the proximal supply port and extending through the elongate
body 1228 to the distal end portion thereof. An expandable balloon
1230 is coupled to the distal end portion of the elongate body
1228, the balloon 1230 having a (preferably at least
semi-compliant) wall 1231, wherein an interior surface 1224 of the
wall 1231 defines an interior 1235 of the balloon 1230. One or more
distal facing coolant dispersion apertures 1237 in fluid
communication with the respective supply lumen 1243 and balloon
interior 1235 are located at the juncture between the distal end
portion of the elongate body 1228 and the balloon wall 1231. The
one or more dispersion apertures are sized and positioned with
respect to the balloon wall 1231, such that a pressurized flowable
coolant in the supply lumen 1243 will enter the balloon interior
1235 through the aperture(s) 1237 in the form of an axially
directed liquid spray 1238 that contacts and provides (due to rapid
evaporation) substantially uniform cooling of a distal facing
energy delivery portion 1239 of the balloon wall 1231.
[0073] Referring to FIG. 17, a further alternative cryogenic tissue
ablation instrument 1320 for use with the system 20 of FIG. 1
includes an elongate flexible body having a distal portion 1329
sized for introduction into a human esophagus, and a plurality of
supply lumens 1343 in fluid communication with one or more
respective proximal coolant supply ports (not shown) and extending
through the elongate body to the distal portion 1329; and an
expandable multi-lobe balloon 1330 carried on the distal portion
1329 and having a plurality of isolated balloon chambers 1330A-C.
The distal portion 1329 extends through a central region of (i.e.,
between the lobes of) the balloon 1330, each of the coolant supply
lumens 1343 may be in fluid communication with a respective one of
the interior balloon chambers 1330A-C via a respective plurality of
coolant dispersion apertures 1337 in the distal portion 1329,
wherein the respective dispersion apertures 1337 are sized and
positioned on the elongate body distal portion 1329 such that a
pressurized flowable coolant in one of the supply lumens 1343 will
enter the respective interior balloon chamber (chamber 1330C is
shown in FIG. 17 by way of illustration) through the respective
dispersion apertures 1337 in the form of a liquid spray 1338 that
contacts and cools of an interior wall surface 1341 of the
respective chamber (1330C). Additionally or alternatively, the
isolated balloon chambers 1330A-C may be in fluid communication
with independent fluid or gas inflation sources through respective
lumens extending through the elongate body (not shown).
[0074] A system including the multi-lobe balloon instrument 1320
further includes a source of pressurized flowable coolant fluidly
coupled to the respective one or more coolant supply ports of the
instrument, and a controller operatively coupled with the source of
pressurized flowable coolant so as to controllable release the
coolant into a respective one or more of the supply lumens
1343.
[0075] Prototype Fabrication and Testing
[0076] Large diameter cryogenic balloon ablation instruments were
fabricated to evaluate temperature profiles at the balloon surface
and in open cell foam models immersed in 37.degree. C. water
external to the balloon. The instruments were fabricated from
endoscopic controlled radial step expansion (CRE) dilation balloons
having diameters that range from 18 to 20 mm, depending on the
inflation pressure. The balloons were attached to enlarged, 0.017
inch (ID) instrument shafts similar to those used for the
PolarCath.TM. vascular cryogenic balloon catheter distributed by
Boston Scientific Corporation. Standard PolarCath.TM. nitrous oxide
N.sub.2O cylinders and control units were used for inflation of the
prototypes. The control units were reprogrammed to run the desired
test cycles. Bench top tests in body temperature water showed that
balloon surface temperatures of -40.degree. C. were reached within
15 seconds, as illustrated in the time-versus-temperature plot in
FIG. 19, where each x-axis mark represents 10 seconds. Temperatures
were measured along the length of the balloons and shown to be
uniform over approximately 4 cm. The dispersion tube apertures were
0.002 inches in diameter and positioned in eight longitudinally
spaced rings. In particular, each ring included eight apertures
formed by laser drilling uniformly spaced around the circumference
of the diffusion tube, offset from adjacent ring apertures by
22.5.degree.. Diffuser tube details are shown in FIGS. 20A-D. The
0.057 inch diameter polyimide diffuser tube was fabricated
separately and adhesively bonded to the fluid supply lumen and
instrument shaft.
[0077] It will be appreciated that various embodiments of the
disclosed inventions may be used to perform methods of treating
esophageal tissue using a cryogenic balloon. Such methods of use
are in themselves further embodiments of the disclosed inventions.
By way of example, in one such embodiment, a method is provided for
ablating esophageal wall tissue using a cryogenic balloon
instrument, the instrument comprising an elongate flexible member
carrying an expandable balloon on a distal end thereof, the balloon
having a collapsed delivery shape and an expanded treatment shape.
In accordance with this embodiment, the method includes (i)
delivering the cryogenic balloon in its delivery shape through a
working channel of an endoscopic instrument to a location in an
esophagus to be treated; (ii) expanding the cryogenic balloon so
that an outer surface of the balloon contacts and smoothes
esophageal wall tissue to be treated; and (iii) delivering a
pressurized flowable coolant from a source external to the patient
through a supply lumen in the elongate body and out one or more
coolant dispersion apertures in the elongate body in fluid
communication with the balloon interior, the one or more coolant
dispersion apertures being sized and positioned relative to an
interior wall of the balloon such that the pressurized flowable
coolant enters the balloon interior in the form of a liquid spray
that contacts and provides substantially uniform cooling of the
interior balloon wall surface of a treatment region of the balloon.
The gas formed as a result of coolant evaporation is carried
through a channel in the elongated flexible instrument and released
through a relief valve at a proximal end of the instrument.
[0078] While certain exemplary embodiments have been described
herein and shown in the accompanying drawings, it is to be
understood that such embodiments are merely illustrative and not
restrictive of the inventive concepts and features, and that the
inventions disclosed herein are not limited to the specific
constructions and arrangements shown and described, as various
further and other modifications may occur to those skilled in the
art upon studying this disclosure.
* * * * *