Bioresorbable stents
Encyclopedia
In medicine, a stent
Stent
In the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...

is any device which is inserted into a blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

 or other internal duct in order to expand the vessel to prevent or alleviate a blockage. Traditionally, such devices are fabricated from metal mesh and remain in the body permanently or until removed through further surgical intervention. A bioresorbable stent serves the same purpose, but is manufactured from a resorbable
Resorption
Resorption is a process by which a structure is remodeled.Types include:* Bone resorption* Root resorption...

 or absorbable
Absorption
Absorption may refer to:- Chemistry and biology :* Absorption , absorption of particles of gas or liquid in liquid or solid material* Absorption , a route by which substances can enter the body through the skin...

 material.

Background

The use of metal drug-eluting stent
Drug-eluting stent
A drug-eluting stent ' is a peripheral or coronary stent placed into narrowed, diseased peripheral or coronary arteries that slowly releases a drug to block cell proliferation. This prevents fibrosis that, together with clots , could otherwise block the stented artery, a process called restenosis...

s presents some potential drawbacks. These include a predisposition to late stent thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...

, prevention of late vessel adaptive or expansive remodeling, hindrance of surgical revascularization, and impairment of imaging with multislice CT
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...

.

To overcome some of these potential drawbacks, several companies are pursuing the development of bioresorbable or bioabsorbable stents. Like metal stents, placement of a bioresorbable stent will restore blood flow and support the vessel through the healing process. However, in the case of a bioresorbable stent, the stent will gradually resorb and be benignly cleared from the body, leaving no permanent implant.

Studies have shown that the most critical period of vessel healing is largely complete by approximately three months. Therefore, the goal of a bioresorbable or “temporary” stent is to fully support the vessel during this critical period, and then resorb from the body when it is no longer needed.

As of September, 2009, bioresorbable stents were limited to clinical investigational use only and had not yet been approved for sale.
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