About 500,000 angioplasties are performed in the United States every year. Dr. Stanley Tocker, a former CECON Group Vice President and consultant in this controversial subject area, reports on important happenings in the research of stents.
Medical stents, small expandable mesh tubes used to open narrowed vascular sites or support weakened vessels, have been in the news in the face of multiple lawsuits and two leading medical societies publishing a report calling stents “one of the five most overused procedures in medicine.” The report called into question elective procedures versus emergency situations using stents for patients having heart attacks—where the life-saving benefit is clear.
Angioplasty typically costs around $30,000, and in rare circumstances it can lead to tears in blood vessel walls, bleeding and the formation of blood clots.
All aspects of the stent design, surgical techniques for their use, anti-plaque coatings, coating methodology and materials of construction have been studied. One aspect of stents where some fascinating research is currently taking place is in the material choice.
Most stents are made of stainless steel mesh coated with drug eluting coatings containing drugs that resist plaque formation at the stent site (restinosis). Other than stainless steel, decomposable metals are being tested for the base platform such as magnesium, iron, zinc and tailored metal alloys. The idea is to have the stent physically break down over time, leave the patient and not act as a possible site for reclogging (restenosis) as might be expected for a foreign body in the vascular system.
Chemists are also currently studying polymeric materials for stents that dissipate over a predetermined time frame. Initially, this work has involved polymers based on polylactic acid, used in dissolvable sutures, but it has branched out to other polymers. Such systems can have minimal systemic toxicity because the breakdown products can be similar to those already present in vivo. For example, lactic acid copolymers such as those having glycolic acid units are being studied as well other non-toxic proprietary systems. These “dissolvable” systems also have been accompanied by anti-plaque drugs used within or as coatings.
The goal in these non-stainless steel stents is to maintain the proper strength to survive the surgery , show favorable ductility, dissolution rate and anti plaque character. Considering that these are critical interrelated factors, this is extremely difficult but important research.
Other questions arise such as if everything works well, with dissolvable or biodeecomposible stents, will the application site “bloom” again and become restricted. After all, the on-site plaque is being compressed by the stent, and not being removed. Of course the patients’ individual genetics, age, diet and other human factors also add to the technical uncertainties and difficulties.
A dissolvable stent is already used in Europe. Depending on the results of current research, it could be approved here in a few years. Will dissolvable or biodeecomposible stents totally replace metal stents? Probably not. But it is potentially a breakthrough innovation in a well-tested therapeutic area.
Dr. Tocker consults in this subject area and is a vice president of the CECON Group. Since 1985, CECON has been placing experts in over 200 scientific disciplines. CECON Consultants include medical device experts, pharmaceutical consultants, clinical trials experts, biotechnology experts, and chemistry experts.