advanced medical technologies

Until the advent of coronary stents, patients with cardiovascular blockages had little choice but to either keep a close eye on their disease (“watchful waiting” with or without accompanying pharmaceutical therapy) or undergo coronary artery bypass grafting (CABG). When angioplasty was developed by Andreas Gruentzig in 1977, patients were presented with the option to undergo angioplasty in an effort to open blocked coronary arteries. While short-term benefits were usually seen with balloon angioplasty, longer-term outcomes showed many arteries re-closing and requiring repeated intervention; up to 50% of angioplasty patients were found to require further angioplasty within six months. In an effort to reduce the frequency of patients requiring reintervention, scientists and clinicians developed stents that could be left behind to hold the artery open once the PTCA balloon was withdrawn.

Unfortunately, clinicians found that bare metal stents (BMS) could cause an immunological response that would try to “protect” the body from the foreign material (i.e., the stent). This, in turn, would lead to further narrowing near to or inside the stent, as seen in roughly 25% of patients receiving BMS devices. To combat this, drug-eluting stents (DES) were developed.

Drug-eluting stents were developed to release a drug (e.g., sirolimus or paclitaxel) intended to reduce the incidence of restenosis. From there, even more innovative products have been developed, such as bioactive stents or stents designed to attract a patient’s own endothelial cells to coat the stent (as in devices by OrbusNeich, Hexacath, and Miami Cardiovascular Innovations).

Other device developers have sought to create stents that will fully degrade and disappear over a period of weeks or months—of a score of companies in this area, Abbott Vascular, Biotronik and REVA Medical appear closest to market. Yet others seek to abandon the use of stents altogether, opting instead to pursue an angioplasty balloon that will leave the anti-inflammatory drugs behind without the accompanying stent, as with CE Mark approved devices by EuroCor (the DIOR catheter) and B. Braun Melsungen (the SeQuent Please catheter).

Because the ultimate therapy has not yet been found, many opportunities still exist for effective therapies to combat atherosclerosis. So far, coronary stents hold the most promise for effectively treating an aging population with an increasing incidence of coronary artery disease.

Types of Coronary Stents and Selected Anti-Restenosis Devices

Stent Type	Description	Examples
Drug-eluting stent	A stent that slowly releases a drug to block cell proliferation and/or restenosis	Cypher (J&J/Cordis), Taxus (Boston Scientific), Xience V (Abbott Vascular), Endeavor (Medtronic)
Bare metal stent, stainless steel	A vascular thin metal wire or mesh stent without a coating, typically first-generation technology	Bx Velocity (J&J/Cordis), Express2 (Medtronic), Millennium Matrix (Sahajanand Medical Technologies)
Bare metal stent, CoCr	A vascular thin metal wire or mesh without a coating, typically next-generation technology	Driver (Medtronic), Multi-Link Vision (Abbott Vascular), Corronnium (Sahajanand Medical Technologies)
Absorbable stent	Completely biodegradable, bioabsorbable stent, typically polymer or magnesium, sometimes coated with anti-restenotic agent	AMS (Biotronik), ABSORB trial (Abbott Vascular), REVA/RESORB trial (REVA Medical), Arterius (West Yorkshire, UK)
Bioactive stent	A stent that reacts with the bodys natural processes to achieve an anti-restenotic effect	Genous (OrbusNeich), Titan2 BAS (Hexacath)
Radioactive stent	Stent with a radiation-emitting coating	(Name undisclosed) (MoBeta, Inc.)
Drug-eluting balloon	Angioplasty balloon that, after deflation, leaves behind an anti-restnotic drug	SeQuent Please (B. Braun Melsungen), DIOR (EuroCor), Elutax (Aachen Resonance)