U.S. patent application number 09/860805 was filed with the patent office on 2002-11-21 for method and apparatus for surgically restoring coronary blood vessels.
Invention is credited to Frazier, O. Howard.
Application Number | 20020173838 09/860805 |
Document ID | / |
Family ID | 25334057 |
Filed Date | 2002-11-21 |
United States Patent
Application |
20020173838 |
Kind Code |
A1 |
Frazier, O. Howard |
November 21, 2002 |
Method and apparatus for surgically restoring coronary blood
vessels
Abstract
A method for surgically restoring a coronary artery having an
atheroma, to more normal structure and function, includes the steps
of: a. making an arteriotomy incision over the length of the
coronary artery atheroma; b. spreading the cut edges of the
arteriotomy incision; c. separating the plaque from the medial
interface of a vessel wall of the coronary artery; d. extracting
the atherosclerotic plaque from the coronary artery, and from any
side branch artery; e. inserting a pre-expanded endocoronary stent
with vessel anchor prongs into the opened coronary artery; f.
closing the coronary artery over the stent with sutures; and g.
applying extravascular drug delivery material over the stent
implantation site. In another feature, the extravascular drug
delivery material provides a local controlled release of bioactive
factors to inhibit both thrombosis and smooth muscle cell
proliferation.
Inventors: |
Frazier, O. Howard;
(Houston, TX) |
Correspondence
Address: |
Tim Headley
GARDERE WYNNE SEWELL LLP
1000 Louisiana, Suite 3400
Hounson
TX
77002-5007
US
|
Family ID: |
25334057 |
Appl. No.: |
09/860805 |
Filed: |
May 18, 2001 |
Current U.S.
Class: |
623/1.15 ;
606/159 |
Current CPC
Class: |
A61F 2220/0008 20130101;
A61B 17/22 20130101; A61F 2/86 20130101; A61F 2250/0067 20130101;
A61B 2017/320741 20130101; A61F 2220/0016 20130101; A61F 2220/0058
20130101 |
Class at
Publication: |
623/1.15 ;
606/159 |
International
Class: |
A61F 002/06; A61B
017/22 |
Claims
What is claimed is:
1. A method for surgically restoring a coronary artery having an
atheroma, to more normal structure and function, comprising the
steps of: a. making an arteriotomy incision over the length of the
atheroma; b. extracting atherosclerotic plaque from the atheroma;
c. inserting a pre-expanded endocoronary stent into the opened
coronary artery; and d. closing the coronary artery over the stent
with sutures.
2. A method for surgically restoring a coronary artery having an
atheroma, to more normal structure and function, comprising the
steps of: a. making an arteriotomy incision over the length of the
coronary artery atheroma; b. spreading the cut edges of the
arteriotomy incision; c. extracting the atherosclerotic plaque from
the coronary artery, and from any side branch artery; d. inserting
a pre-expanded endocoronary stent into the opened coronary artery;
and e. closing the coronary artery over the stent with sutures.
3. A method for surgically restoring a coronary artery having an
atheroma, to more normal structure and function, comprising the
steps of: a. making an arteriotomy incision over the length of the
coronary artery atheroma; b. spreading the cut edges of the
arteriotomy incision; c. separating the plaque from the medial
interface of a vessel wall of the coronary artery; d. extracting
the atherosclerotic plaque from the coronary artery, and from any
side branch artery; e. inserting a pre-expanded endocoronary stent
into the opened coronary artery; and f. closing the coronary artery
over the stent with sutures.
4. A method for surgically restoring a coronary artery having an
atheroma, to more normal structure and function, comprising the
steps of: a. making an arteriotomy incision over the length of the
coronary artery atheroma; b. spreading the cut edges of the
arteriotomy incision; c. separating the plaque from the medial
interface of a vessel wall of the coronary artery; d. extracting
the atherosclerotic plaque from the coronary artery, and from any
side branch artery; e. inserting a pre-expanded endocoronary stent
into the opened coronary artery; f. closing the coronary artery
over the stent with sutures; and g. applying extravascular drug
delivery material over the stent implantation site.
5. The method of claim 4, wherein the extravascular drug delivery
material provides a local controlled release of bioactive factors
to inhibit both thrombosis and smooth muscle cell
proliferation.
6. The method of any of claims 1-5, wherein the pre-expanded
endocoronary stent has calibrated diameter, length, and
curvature.
7. An endocoronary stent comprising: a spine; multiple ribs
connected to the spine; and multiple vessel anchor prongs connected
to the ribs, wherein each rib is circular in shape, encompasses 75%
of the stent circumference, is manufactured from 316L stainless
steel or tantalum, and has a thickness of no more than 0.12 mm.
8. The endocoronary stent of claim 7, wherein it is fabricated from
a biocompatible material, is radially non-compressible, and is
axially semi-flexible.
9. The endocoronary stent of claim 7, having a diameter of any one
of the following sizes: 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, and
5.0 mm.
10. The endocoronary stent of claim 7, having a length of any one
of the following sizes: 20 mm, 25 mm, 40 mm, 50 mm, 60 mm and 75
mm.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to methods and
devices for performing coronary artery revascularization surgery.
More specifically, it relates to methods and devices for repairing
partially blocked coronary arteries, including the use of
stents.
BACKGROUND OF THE INVENTION
[0002] Coronary artery disease is the leading cause of death and
disability in the major industrialized countries of the world.
Treatment of advanced atherosclerotic coronary artery disease,
beyond that amenable to therapy via medication alone, now generally
includes interventional cardiology procedures in the form of
Percutaneous Transluminal Coronary Angioplasty (PTCA) or
cardiovascular surgery procedures in the form of Coronary Artery
Bypass Grafting (GABG).
[0003] The PTCA technique involves the retrograde introduction from
an artery in the leg or arm, of a catheter with a small dilating
balloon at its tip. The catheter is advanced through the arteries
by fluoroscopic guidance and is passed across the luminal narrowing
of the coronary artery over a guide wire. Once in place, the
catheter balloon is inflated for a short period of time. This
results in mechanical deformation of the atherosclerotic plaque or
the vessel wall with a subsequent increase in the cross-sectional
area of the artery. This in turn reduces vessel obstruction and
transluminal pressure gradients, and increases blood flow through
the coronary artery.
[0004] PTCA or angioplasty is a term that now may include other
percutaneous transluminal methods of decreasing stenosis within a
coronary blood vessel besides balloon dilation alone. These methods
include: lumen expansion with an endoluminal stent that prevents
elastic recoil of the vessel; mechanical atherectomy with shaving,
extraction, thermal ablation or ultrasonic pulverization of the
lesion; and methods of endoluminal drug delivery or radiation
treatment. Mechanical atherectomy may result in incomplete plaque
removal, particularly in the side branch vessels of the artery,
and/or embolization of plaque debris to the downstream coronary
circulation. In addition, it is difficult, and sometimes impossible
to provide complete coronary revascularization with PTCA techniques
for patients with total vessel occlusions, long obstructions, or
diffuse lesion sites. During the year 2000, approximately 1.4
million patients worldwide underwent PTCA procedures.
[0005] The CABG technique involves placing the patient on
cardiopulmonary bypass (heart-lung machine), and temporarily
stopping the heart muscle. Surgery is then affected on the coronary
arteries in the form of bypass conduit vessels using vein or artery
grafts from the aorta to the coronary artery distal to the lesion
sites, thereby providing blood flow around the obstructions.
Compared to PTCA procedures, CABG surgery provides more complete
revascularization for patients with multi-vessel coronary artery
disease. During the year 2000, it is estimated that 1 million
patients underwent CABG surgery worldwide.
[0006] The profile of patients undergoing CABG surgery is
continuously changing. Today, patients being referred for CABG
surgery are older, and many have undergone previous
revascularization procedures. Therefore, the number of patients
having severe and diffuse coronary disease has been increasing.
Diffuse multi-vessel coronary artery disease is a challenge for
surgeons, precluding complete revascularization in some patients,
while rendering others inoperable. Incomplete revascularization is
one of the most important variables, affecting both operative and
late mortality following CABG surgery. In particular, residual
disease of the left anterior descending (LAD) artery has been shown
to adversely affect patient survival. Recently, the application of
new revascularization procedures, aimed at growing new coronary
blood vessels using laser devices or angiogenesis drugs, has
refocused attention on the surgical management of diffuse coronary
artery disease. For patients with total vessel occlusions, long
obstructions, or severe diffuse coronary disease, an endarterectomy
procedure (removal of the atherosclerotic plaque) may be the only
option that can produce good clinical results in otherwise
inoperable situations.
[0007] Surgical endarterectomy of the right coronary artery (RCA)
requires a different technique from that used for the LAD. The RCA
and its atheromatous core are of a large caliber, thick, and
strong. Further, the main RCA trunk and its major branches (the
posterior descending and the posterolateral vessels) are in the
same geometric plane. Therefore, RCA endarterectomy can usually be
accomplished by the traction-counter-tracti- on technique with or
without mechanical assistance (i.e. gas dissection of the lesion
from the vessel wall) through a relatively short vessel incision
(arteriotomy).
[0008] In contrast, the LAD atheromatous core is narrow and
delicate, and its thickness is usually uneven, being thicker and
stronger near vessel bifurcations, and thinner in between the side
branches, increasing the risk of plaque disruption under tension.
Furthermore, the LAD artery has many branches that come off at two
different geometric planes 90.degree. apart (the septal and
diagonal branches). When traction is applied to the atheromatous
LAD core directed at extracting one set of branch vessels it exerts
a sheering force on the other side branches, breaking the plaque
off, and occluding the vessels ("snowplow effect"). Therefore,
endarterectomy of the LAD artery should be done through a long
arteriotomy incision that allows for the complete removal of
atheromatous plaque from the main vessel and side branches under
direct vision. Following endarterectomy, a vein patch is often
required to close the artery before the distal bypass graft
anastomosis can be performed.
[0009] Despite the major therapeutic advances in the treatment of
coronary artery disease provided by PTCA interventions and CABG
surgery, the long-term success of these procedures has been
hampered by the development of vessel re-narrowing or re-closure.
Abrupt vessel occlusion may develop during a period of hours to
days post-procedure, due to vasospasm and/or thrombosis at the site
of vessel injury. The most common and major limitation, however, is
the development of progressive reversion of the diseased vessel to
its previous stenotic condition, negating any gains achieved from
the procedure. This gradual re-narrowing process is most commonly
due to vessel constriction and/or to intimal hyperplasia, and is
referred to as restenosis. Restenosis is generally believed to be a
normal reparative response to endovascular injury after
angioplasty, and in vein grafts following vessel bypass surgery.
The sequence of events is similar for PTCA and CABG restenosis,
progressing through the process of vasoconstriction, thrombus
formation and organization, growth factor and cytokine release, and
smooth muscle cell proliferation.
[0010] Clinical follow-up studies indicate that significant vessel
restenosis occurs in about 40% of balloon angioplasty patients and
in about 25% of the PTCA/stent patients within six months, and in
about 20% of the CABG patients within one year. This complication
of vessel restenosis results in increased patient morbidity, need
for repeating the procedure, and escalating medical costs. With an
estimated 2,400,000 PTCA and CABG procedures performed worldwide in
2000 for coronary artery revascularization, these percentages of
restenosis mean as many as 640,000 patients may develop vessel
restenosis within one year after operation. Thus, repeat procedures
could account for over $9 billion in additional healthcare costs,
which increase each year.
[0011] Coronary artery stents are known in the prior art. There are
two broad groups of endocoronary stent devices: 1) balloon
expandable and 2) self-expanding. Within these groups, there is
substantial variability with regards to manufacturing techniques,
materials, architecture, dimensions, surface coatings (i.e., drugs,
radiation, or other biological material), and strut configurations.
However, these stents, used only by cardiologists and not by
cardiovascular surgeons, cannot be implanted in a coronary artery
at the site of a major side branch vessel, because the stent may
block or occlude the opening of the side branch vessel. Often the
diseased area of a coronary artery is several centimeters in
length, from which there are several side branch vessels,
particularly for the LAD.
[0012] Drug delivery stents designed to inhibit stent thrombosis
and intimal hyperplasia, termed restenosis, are known in the prior
art. Drug delivery stents may not be completely effective, however,
because of low tissue drug levels, drug washout into the blood
stream, inflammatory response caused by the drug eluting coating,
and increased stent dimensions due to coating thickness.
[0013] Thus, there is a need for improving the way coronary artery
revascularization surgery is performed, that results in more
complete and durable outcomes for patients, physicians, and
healthcare delivery systems.
SUMMARY OF THE INVENTION
[0014] A preferred embodiment of the present invention provides for
a surgical method to treat long stenosis within a coronary artery,
preferably the left anterior descending coronary artery, the
circumflex coronary artery and branches, and the right coronary
artery. The surgical method, open endarterectomy, involves
performing an extended arteriotomy incision over the entire length
of the lesion, with removal of atherosclerotic plaque from the side
branches of the diseased coronary blood vessel. Another feature of
the preferred method allows for treatment of the occlusive lesion
regardless of length and composition.
[0015] Another preferred feature of the present invention allows
for closure of the long arteriotomy with sutures over a catheter of
calibrated diameter and length. The catheter is gradually removed
from the vessel during closure. Another feature of the invention
allows for the coronary catheter to be used for the endocoronary
seeding of autologous cells harvested from the patient. Cell
seeding is intended to enhance healing and re-growth of the vessel
lining. The endoluminal catheter may also be used for local
injection of vasoactive drugs during vessel closure. Drugs include,
but are not limited to, vasodilator nitric oxide donor drugs such
as nitroglycerin and sodium nitroprusside, or prostacyclin donor
drugs such as alprostadil. These drugs, given alone or in
combination, are intended to prevent vessel spasm during coronary
artery closure.
[0016] Another feature of the present invention provides for a
surgical method to remove atherosclerotic plaque from a diseased
coronary artery, and then to implant a pre-expanded stent device
into the coronary artery with subsequent suture closure of the
artery over the endocoronary stent. In one preferred embodiment,
the endocoronary stent maintains an optimal vessel diameter, and
prevents over-sewing of the vessel walls. Another feature of the
present invention provides for an open-ended (non-circumferential),
rib-like endocoronary stent having anchor prongs attached to the
stent rib for fixation to the vessel wall. The anchor prongs
provide a means for increasing the radial strength of the stent,
and preventing stent compression and collapse.
[0017] Another feature of the present invention provides for an
open-ended (non-circumferential), rib-like endocoronary stent
having a textured luminal surface.
[0018] Another feature of the present invention is a method and
product for extravascular topical drug delivery directly to the
coronary artery surgery site. The drug delivery method and product
includes one or more drugs, including gene therapy agents, with a
controlled release rate without systemic side effects, for use in
conjunction with the endocoronary stent, to limit or prevent the
development of stent thrombosis and intimal hyperplasia.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present invention may be more completely and easily
understood when taken in conjunction with the accompanying line
drawings, in which:
[0020] FIG. 1 is an enlarged cross-sectional end view of a
pre-expanded surgically implanted endocoronary stent manufactured
according to a preferred embodiment of the present invention.
[0021] FIG. 2a is a side view of the pre-expanded endocoronary
stent shown in FIG. . 1.
[0022] FIG. 2b is a top view of the pre-expanded endocoronary stent
shown in FIG. . 1.
[0023] FIG. 3 is an enlarged cross-sectional side view drawing of a
diseased and occluded epicardial coronary artery, and perforating
side branch vessel in a patient.
[0024] FIG. 4 is an enlarged cross-sectional end view through the
side branch of the diseased coronary artery shown in FIG. . 3.
[0025] FIG. 5 is a cross-sectional end view of the diseased
coronary artery showing a long arteriotomy with exposure of the
atherosclerotic plaque.
[0026] FIG. 6 is a cross-sectional end view of the diseased
coronary artery illustrating complete extraction of the
atherosclerotic plaque including side branch plaque through the
long artenotomy.
[0027] FIG. 7 is a cross-sectional end view of the coronary artery
following plaque removal showing insertion of a pre-expanded
endocoronary stent, as shown in FIG. 1, through the long
arteriotomy, into the blood vessel lumen.
[0028] FIG. 8 is a cross-sectional end view of the coronary artery
following implantation of the stent device and suture closure of
the arteriotomy over the stent.
[0029] FIG. 9 is a cross-sectional end view of the coronary artery
with surgically implanted endocoronary stent and extravascular drug
delivery implant.
[0030] FIG. 10 is a cross-sectional side view of the coronary
artery with surgically implanted endocoronary stent and
extravascular drug delivery implant.
[0031] FIG. 11 is an enlarged cross-sectional top view of a
pre-expanded endocoronary stent with vessel anchor prong, according
to a preferred embodiment of the present invention.
[0032] FIG. 12 is a side view of the pre-expanded endocoronary
stent with vessel anchor prong shown in FIG. 11.
[0033] FIG. 13 is an enlarged side view of the stent anchor prong
shown in FIG. 11.
DETAILED DESCRIPTION
[0034] In the drawings, like numerals designate like parts
throughout the drawings. In FIG. 1, a pre-expanded surgically
implanted endocoronary stent 10 includes a spine member 12 having a
rib 14. The rib 14 is circular in shape, and encompasses 75% of the
stent 10 circumference. The endocoronary stent 10 is 316L stainless
steel or tantalum wire, having a thickness of 0.12 mm. The
endocoronary stent 10 has a diameter 16 of any one of the following
sizes: 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, and 5.0 mm.
Referring to FIG. 2a, the pre-expanded endocoronary stent 10 has a
length 18 of any one of the following sizes: 20 mm, 40 mm, or 60
mm. Referring to FIG. 2b, the endocoronary stent 10 has four ribs
14. The endocoronary stent 10 has a textured surface, which may be
polymeric or a powdered metal. The textured surface provides a
bonding matrix for enhanced cell seeding of the endocoronary stent
with autologous endothelial cells.
[0035] Referring to FIG. 3, a diseased and occluded epicardial
coronary artery 20 has a perforating side branch vessel 22. A wall
of the epicardial coronary artery 20 consists of outer media and
adventitia layers 26, which are composed of smooth muscle cells and
connective tissue, and an inner intima layer 28, which is normally
lined by endothelial cells. Likewise, the wall of the perforating
side branch vessel 22 consists of media and adventitia layers 30,
and an inner intima layer 32. Atherosclerotic plaque 34 most
commonly consists of calcific, fibrous or mixed composition
material. The atherosclerotic plaque 34 commonly extends into the
side branch vessel 36. The area with the plaque 34 is referred to
as an atheroma. FIGS. 3 and 4 illustrate the diameters of normal,
non-diseased, blood vessel lumens 38, 40, and stenosed vessel
lumens 42, 44 of the epicardial coronary artery 20 and side branch
vessel 22, respectively.
[0036] Referring to FIG. 5, the epicardial coronary artery 20 and
perforating side branch vessel 22 have been surgically opened by
the surgeon with a long arteriotomy incision 48. The
atherosclerotic plaque 34 is exposed by spreading the cut edges of
the arteriotomy 50, and separating the plaque 34 from the medial
interface of the vessel wall 52. Referring to FIG. 6, the surgeon
extracts the atherosclerotic plaque 34 from the epicardial artery
20, and from the side branch artery 22. This extraction of plaque
is referred to as an endarterectomy.
[0037] Referring to FIG. 7, following plaque removal, the surgeon
inserts the pre-expanded endocoronary stent 10 through the
arteriotomy 48. Referring to FIG. 8, the surgeon closes the
arteriotomy incision 50 over the pre-expanded endocoronary stent 10
by sutures 60. This closure is referred to as anastomosis.
[0038] Referring to FIG. 9 and FIG. 10, a perivascular drug
delivery matrix 62 is applied over the anastomosis 60. The matrix
may consist of a non-biodegradable polymer (for example,
polyurethane, silicone), a biodegradable polymer (i.e.,
poly-L-lactic acid), or an absorbable biopolymer (for example,
fibrin). The extra-coronary matrix is loaded with a bioactive agent
64 providing local controlled drug release. Cardiovascular drugs
for extravascular delivery can include vasodilator, antiplatelet
antimitotic, angiogenic and gene therapy agents. The duration for
controlled drug release can range from 3 to 14 days. The drugs may
be of any type which would be useful in preventing acute vessel
thrombosis, antiplatelet, and/or antithrombotic agents inhibiting
chronic restenosis of the vessel, antimitotic agents to limit
smooth muscle cell proliferation, and promoting endothelial cell
growth. U.S. Pat. Nos. 5,681,278 and 5,900,433, the disclosures of
which are incorporated by reference, describe known methods for
forming extracoronary artery drug delivery implants that are
suitable for this invention.
[0039] In FIG. 11, a pre-expanded surgically implanted endocoronary
stent 68 includes vessel anchor prongs 70 attached to the stent
ribs 14 for fixation to the vessel wall. The anchor prong 70
provides a means for increasing the radial strength of the stent
68, and preventing stent compression and collapse. The rib 14 is
circular in shape, encompasses 75% of the stent 68 circumference,
and attaches to the spine 12. The endocoronary stent 68 is a 316L
stainless steel, or Elgiloy alloy, or tantalum wire, having a
thickness of 0.12 mm. The endocoronary stent 68 has a diameter 16
of any one of the following sizes: 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm,
4.5 mm, and 5.0 mm.
[0040] The endocoronary stent 68 is radially non-compressible, and
axially semi-flexible, having minimal material volume and mass. The
endocoronary stent 68 has a low profile when implanted into the
vessel lumen, and is designed not to occlude or obstruct the
coronary artery side branches. The endocoronary stent 68 is
radiopaque and biocompatible for long-term implantation with
minimal trauma to the vessel wall.
[0041] Referring to FIG. 12, the pre-expanded endocoronary stent 68
has a stent height 72, which is equal to 85% of the stent diameter
16, and has a manufactured length 18 of any one of the following
sizes: 25 mm, 50 mm, or 75 mm. The number of stent ribs 14 is equal
in number (N) to stent length 18 divided by 5 (i.e., 5, 10, and 15
N for lengths of 25 mm, 50 mm, and 75 mm, respectively). Rib 14
diameter (D1) is equal to stent length 18 divided by rib number
(N)-1. For example, for 50 mm stent length, D1=50/(10-1)=5.56 mm.
FIG. 13 is an enlarged side view of the stent rib 14 and a vessel
anchor prong 70. The anchor prong 70 is laser welded to alternating
ribs 14. The length of the prong between the ribs=D1-wire thickness
of 0.12 mm. The length of the prong for implantation into the
vessel wall for fixation=10% of the stent diameter 16 times 3.1415.
For example, for a 4 mm stent diameter, prong
length=0.1(4.times.3.1415)=1.26 mm.
[0042] In summary, the present invention is both an apparatus and a
method, which includes the following steps:
[0043] a. performing an extended arteriotomy over the length of the
coronary artery atheroma;
[0044] b. spreading the cut edges of the arteriotomy incision;
[0045] c. separating the plaque from the medial interface of the
vessel wall;
[0046] d. extracting the atherosclerotic plaque from the epicardial
artery, and from any side branch artery;
[0047] e. inserting a pre-expanded stent device with vessel anchor
prong, of calibrated diameter, length, and curvature, into the
opened-artery lumen;
[0048] f. closing the coronary artery over the stent with sutures;
and
[0049] g. treating the coronary artery surgery site with a drug
delivery material, extravascular to the stent implantation site,
for local controlled release of bioactive factors to inhibit both
thrombosis and smooth muscle cell proliferation.
[0050] This procedure may be performed on the non-beating heart
during cardiopulmonary bypass, or on the beating unloaded heart
with the aid of a heart bypass system. The procedure may also be
performed on the heart ex vivo with the aid of cardiopulmonary
bypass followed by autotransplantation.
[0051] The present invention provides a method and apparatus for
restoring the structure and function of a diseased coronary blood
vessel. Other blood vessels can also be surgically treated and
stented without departing from the scope of the present invention.
The invention is not intended to be limited to the specifics of the
described preferred embodiments, but is defined by the accompanying
claims.
* * * * *