Expandable myocardial implant

Details Expandable myocardial implant Expandable myocardial implant

2000-04-13

2002-02-26

McDermott, Corrine (Department: 3738)

Surgery

Devices transferring fluids from within one area of body to...

C623S001100, C623S001120, C600S016000, C606S151000, C128S898000

Reexamination Certificate

active

06350248

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method and apparatus for performing a coronary artery bypass procedure. More particularly, the present invention performs a coronary artery bypass utilizing a number of approaches including an open-chest approach (with and without cardiopulmonary bypass), a closed-chest approach under direct viewing and/or indirect thoracoscopic viewing (with and without cardiopulmonary bypass), and an internal approach through catheterization of the heart and a coronary arterial vasculature without direct or indirect viewing (with and without cardiopulmonary bypass).
2. Description of the Prior Art
Coronary artery disease is the leading cause of premature death in industrialized societies. But the mortality statistics tell only a portion of the story; many who survive face prolonged suffering and disability.
Arteriosclerosis is “a group of diseases characterized by thickening and loss of elasticity of arterial walls.” D
ORLAND
'
S
I
LLUSTRATED
M
EDICAL
D
ICTIONARY
137 (27th ed. 1988). Arteriosclerosis “comprises three distinct forms: atherosclerosis, Monckeberg's arteriosclerosis, and arteriolosclerosis.” Id.
Coronary artery disease has been treated by a number of means. Early in this century, the treatment for arteriosclerotic heart disease was largely limited to medical measures of symptomatic control. Evolving methods of diagnosis, coupled with improving techniques of post-operative support, now allow the precise localization of the blocked site or sites and either their surgical re-opening or bypass.
The re-opening of the stenosed or occluded site can be accomplished by several techniques. Angioplasty, the expansion of areas of narrowing of a blood vessel, is most often accomplished by the intravascular introduction of a balloon-equipped catheter. Inflation of the balloon causes mechanical compression of the arteriosclerotic plaque against the vessel wall. Alternative intravascular procedures to relieve vessel occlusion include atherectomy, which results in the physical desolution of plaque by a catheter equipped (e.g. a cutting blade or high-speed rotating tip). Any of these techniques may or may not be followed by the placement of mechanical support and called a “stent,” which physically holds the artery open.
Angioplasty, and the other above-described techniques (although less invasive than coronary artery bypass grafting) are fraught with a correspondingly greater failure rate due to plaque reformation. Contemporary reports suggest re-stenosis is realized in as many as 25 to 55 percent of cases within 6 months of successful angioplasty. See Bojan Cercek et al., 68 A
M
. J. C
ARDIOL
. 24C-33C (Nov. 4, 1991). It is presently believed stenting can reduce the re-stenosis rate.
A variety of approaches to delay or prevent re-blockage have accordingly evolved. One is to stent the site at the time of balloon angioplasty. Another is pyroplasty, where the balloon itself is heated during inflation. As these alternative techniques are relatively recent innovations, it is too early to tell just how successful they will be in the long term. However, because re-blockage necessitates the performance of another procedure, there has been renewed interest in the clearly longer-lasting bypass operations.
The current indications for coronary artery bypass grafting have been outlined. See L
UDWIG
K. V
ON
S
EGESSER
, A
RTERIAL
G
RAFTING
F
OR
M
YOCARDIAL
R
EVASCULARIZATION
: I
NDICATIONS
, S
URGICAL
T
ECHNIQUES
A
ND
R
ESULTS
4-5 (1990). Criteria vary dependent upon whether the intent is therapeutic (that is, to reverse cardiac compromise in the patient currently suffering symptoms), or prophylactic (that is, to prevent a potentially fatal cardiac event from occurring in someone who is, at present, symptom free). Id.
The traditional open-chest procedure requires an incision of the skin anteriorly from nearly the neck to the navel, the sawing of the sternum in half longitudinally, and the spreading of the ribcage with a mechanical device to afford prolonged exposure of the heart cavity. If both lungs are deflated, a heart-lung, or cardiopulmonary bypass procedure, is also necessary.
Depending upon the degree and number of coronary vessel occlusions, a single, double, triple, or even greater number of bypass procedures may be necessary. Often each bypass is accomplished by the surgical formation of a seperate conduit from the aorta to the stenosed or obstructed coronary artery, at a location distal to the diseased site. A major obstacle has been the limited number of vessels that are available to serve as conduits. Potential conduits include the two saphenous veins of the lower extremities, the two internal thoracic arteries under the sternum, and the single gastroepiploic artery in the upper abdomen. Theoretically, if all of these vessels were utilized, the procedure would be limited to a quintuple (5-vessel) bypass. Because of this, newer procedures using a single vessel to bypass multiple sites have evolved. However, this technique is fraught with its own inherent hazards, though. When a single vessel is used to perform multiple bypasses, physical stress (e.g., torsion) on the conduit vessel can result. Such torsion is particularly detrimental when this vessel is an artery.
Unfortunately, attempts at using vessels from other species (xenografts), or other non-related humans (homografts) has been largely unsuccessful. See L
UDWIG
K. V
ON
S
EGESSER
, A
RTERIAL
G
RAFTING
F
OR
M
YOCARDIAL
R
EVASCULARIZATION
: I
NDICATIONS
, S
URGICAL
T
ECHNIQUES
A
ND
R
ESULTS
38-39 (1990). Similarly, trials with synthetic alternatives have not been encouraging. See Id. at 39.
While experimental procedures transplanting alternative vessels continue to be performed, in general clinical practice there are five vessels available to use in this procedure over the life of a particular patient. Once these “spare” vessels have been sacrificed, there is little or nothing that modern medicine can offer. It is unquestionable that new methods, not limited by the availability of such conduit vessels, are needed.
In the past, the normal contractions of the heart have usually been stopped during suturing of the bypass vasculature. This can be accomplished by either electrical stimulation which induces ventricular fibrillation, or through the use of certain solutions, called cardioplegia, which chemically alter the electrolytic milleau surrounding cardiac muscles. Stoppage of the heart enhances visualization of the coronary vessels, while removing the need for blood flow through the coronary arteries during the procedure. This provides the surgeon with a “dry field” in which to operate and create a functional anastomosis. After the coronary artery bypass procedure is completed, cardioplegia is reversed, and the heart electrically stimulated if necessary. As the heart resumes the systemic pumping of blood, the cardiopulmonary bypass is gradually withdrawn. The separated sternal sections are then re-joined, and the overlying skin and saphenous donor site or sites (if opened) are sutured closed.
The above-described procedure is highly traumatic. Immediate post-operative complications include infection, bleeding, renal failure, pulmonary edema and cardiac failure. The patient must remain intubated and under intensive post-operative care. Narcotic analgesia is necessary to alleviate the pain and discomfort.
The most troubling complication, once the immediate post-surgical period has passed, is bypass vessel re-occlusion. This has been a particular problem with bypass grafting of the left anterior descending coronary artery when the saphenous vein is employed. Grafting with the internal thoracic (internal mammary) artery results in long-term patency rate superior to saphenous vein grafts, particularly when the left anterior descending coronary artery is bypassed. Despite this finding, some cardiothoracic surgeons continue to utilize the saphenous vein because the internal thoracic artery is smaller in diameter and more

Affiliated with

Also associated with

Rating

Expandable myocardial implant does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Expandable myocardial implant, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Expandable myocardial implant will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2959929