Autologous vascular grafts created by vessel distension

Details Autologous vascular grafts created by vessel distension Autologous vascular grafts created by vessel distension

1999-05-28

2001-11-27

Dvorak, Linda C. M. (Department: 3739)

Surgery

Instruments

C606S159000, C623S903000, C600S036000

Reexamination Certificate

active

06322553

ABSTRACT:

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
The present invention is generally in the area of methods and devices to obtain vascular tissue grafts and more specifically in the area of methods and devices to obtain autologous grafts prepared from living vascular tissue.
Vascular grafts are commonly used by surgeons to bypass obstructions to blood flow caused by the presence of atherosclerotic plaques. Vascular grafts also are used to treat other vascular problems. Grafts for bypass are often, but not exclusively, used in the coronary arteries, the arteries that supply blood to the heart. The materials used to construct a vascular graft usually are either synthetic or of biological origin, but combinations of synthetic and biological materials are also under development. The most successful biological vascular grafts are autologous saphenous vein or mammary artery. Some common synthetic grafts are made of polytetrafluoroethylene (PTFE) (GORTEX™) or polyester (DACRON™). Autologous grafts have generally been used more successfully than synthetic grafts. Autologous grafts remain patent (functional) much longer than synthetic grafts, but saphenous veins are seldom functional more than five years. The short lifetime of synthetic grafts is especially evident with small diameter grafts, as most small diameter synthetic grafts occlude within one to two years.
Mammary artery is the autologous graft of choice, because it typically has a longer life than venous grafts (95% patent at 5 years versus 85% patent at 2 years). Mammary arterial tissue, however, is difficult to harvest and typically is not available in lengths sufficient for effective bypass. Moreover, obtaining sufficient venous tissue for repairing an occluded artery is problematic.
In some cases, autologous or homologous saphenous vein preserved by freezing or other processes is used.
With people living longer, multiple surgeries are more common. At the same time, open heart surgery is becoming more routine, aided by the development of new, minimally invasive procedures which have dramatically simplified the surgery and reduced the recovery time. Development of a longer lasting small-diameter vascular graft is the subject of much academic and industrial research. One current approach is to combine cell culture and biomaterials technologies to make a living, “tissue engineered” graft. This effort, however, is hindered by the requirements of a successful graft: it should be self-repairing, non-immunogenic, non-toxic, and non-thrombogenic. The graft also should have a compliance comparable to the artery being repaired, be easily sutured by a surgeon, and not require any special techniques or handling procedures. Grafts having these characteristics are difficult to achieve. Despite the substantial effort to date and the potential for significant financial reward, academic and industrial investigators have failed to produce graft materials which have demonstrated efficacy in human testing.
Efforts to avoid or minimize the need for vascular grafts for repair of otherwise healthy vascular tissue have been described. For example, Ruiz-Razura et al.,
J. Reconstructive Microsurgery
, 10(6):367-373 (1994) and Stark et al.,
Plastic and Reconstructive Surgery
, 80(4):570-578 (1987) disclose the use of a round microvascular tissue expander for acute arterial elongation to examine the effects on the tissue of such acute hyperextension. The expander is a silicone balloon that is placed under the vessel to be elongated. The balloon is filled with saline over a very short period of time, causing acute stretching and elongation of the vessel. The method is purported to be effective for closure of arterial defects up to 30 mm without the need for a vein graft. These techniques are appropriate for trauma, but are not used for restoring blood flow in vessels that are occluded, for example by disease, which are treated by surgically bypassing the obstruction with a graft. The disclosed methods and devices fail to provide an autologous graft or versatile substitute. Moreover, the acute stretching may damage the vessel.
Accordingly, it is an object of the invention to provide a method, and devices therefor, for creating an autologous blood vessel graft.
SUMMARY OF THE INVENTION
A method for creating an autologous vessel graft is provided, wherein vessel distension is used to stimulate growth of a donor vessel for grafting. Devices useful in the method are provided to stretch the vessel rectilinearly, curvilinearly, or in a combination thereof The devices can be implanted, for example using endoscopic techniques, in a bypass surgery patient prior to the bypass surgery, in order to create blood vessel grafts. The distended portion of the donor vessel is excised at the time of the bypass surgery. The ends of the donor vessel are then sutured end to end to repair the donor vessel, a procedure common in vascular repair and generally accomplished without complication. In an alternative embodiment, a section of donor vessel is surgically excised from the bypass surgery patient and then distended in vitro in a medium for cell growth. The result using either approach is a totally autologous, living vascular graft.
The device preferably includes a stretching mechanism which is attached to a donor blood vessel, means for operating the stretching mechanism to cause the vessel to distend, and a controller, preferably externally located, for controlling the operating means. In a preferred embodiment for rectilinear stretching using vessel attachment points that are movable relative to one another, the device includes a pair of opposed straps, which can be attached to a healthy, small-diameter donor blood vessel such as a femoral artery in the leg. The straps are displaced from each other over a period of time to continuously distend or elongate the donor vessel.
In another preferred embodiment, the device includes a stretching mechanism having vessel attachment points that are fixed relative to one another during the stretching operation. For example, the stretching mechanism can include a rigid surface having two opposing flexible ends that are fixedly attached to the donor vessel, and an inflation or expansion means, such as a balloon, disposed between the flexible ends adjacent the rigid surface. The vessel is distended in a curvilinear manner as the inflation or expansion means is inflated or expanded.
In another preferred embodiment, the device includes a stretching mechanism that provides both rectilinear and curvilinear stretching. For example, the stretching mechanism can include a curved or angled surface having two opposing flexible ends that can be fixedly attached to the donor vessel, wherein the ends can be drawn towards one another.


REFERENCES:
patent: 5078726 (1992-01-01), Kreamer
patent: 5344425 (1994-09-01), Sawyer
patent: 5549664 (1996-08-01), Hirata et al.
patent: 5702419 (1997-12-01), Berry et al.
patent: 5713917 (1998-02-01), Leonhardt et al.
patent: 5879875 (1999-03-01), Wiggins et al.
patent: 5888720 (1999-03-01), Mitrani
patent: 5899936 (1999-05-01), Goldstein
Birukov, et al., “Stretch affects phenotype and proliferation of vascular smooth muscle cells,”Mol Cell Biochem. 144(2):131-39 (1995).
Conklin, B.Viability of Porcine Common Carotid Arteries in a Novel Organ Culture System MS Thesis, Georgia Institute of Technology, 1997.
Costa, et al., “Increased elastin synthesis by cultured bovine aortic smooth muscle cells subjected to repetitive mechanical stretching,”FASEB J.5:A1609-7191 (1991).
Kanda, et al., “Phenotypic reversion of smooth muscle cells in hybrid vascular prostheses,”Cell Transplant. 4(6):587-95 (1995).
Leung, et al., “Cyclic stretching stimulates synthesis of matrix components by arterial smooth muscle cells in vitro,”Science. 191(4226,:475-77 (1976).
Ruiz-Razura, et al., “Acute Intraoperative arterial elongation: Histologic, morphologic, and vascular reactivity studies,”J. Reconstructive Microsurgery, 10(6):367-73 (1994).
Stark, et al., “Rapid elongation of arteries and vein

Affiliated with

Also associated with

Rating

Autologous vascular grafts created by vessel distension does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Autologous vascular grafts created by vessel distension, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Autologous vascular grafts created by vessel distension will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2604704