The field of interventional cardiology has been one of innovation from the beginning. Its early history was driven by the persistence of forward-thinking cardiologists in the face of slow recognition of major advances. Today, advanced technologies offer the promise of improvement on existing, life-saving and life-improving interventional procedures.
The Future of Angioplasty
Angioplasty is a procedure performed to open narrowed or blocked blood vessels. It is used to stop heart attacks in progress, treat chest pain (angina), and restore blood flow through the carotid, peripheral, and renal arteries. During angioplasty, a thin, flexible tube called a catheter is inserted into an artery and fed to the site of a blockage within the blood vessel. The interventional cardiologist opens a tiny balloon at the end of the catheter to push aside the blockage, improving blood flow through the artery.
The future of angioplasty can be thought of as “angioplasty plus.” Medical researchers are working on ways to take current angioplasty practices and improve on them or add adjunctive therapies. One focus for the near-term future is on treating places of flexion: the hip joint, knee, etc. Currently, it is often not desirable to place stents in these areas. Angioplasty alone has often yielded higher than desired rates of restenosis (growth of scar tissue that can cause reblockage of a site that has been previously cleared with angioplasty). Innovations continue in angioplasty to try to treat these challenging locations.
Drug-eluting (coated) balloons are another emerging area. Drug-eluting balloons are balloon catheters that are coated with a drug that, when pressed into the artery wall, delays the growth of scar tissue. This treatment has not yet been approved by the Food and Drug Administration (FDA) for use in the United States, although they have been approved in Europe.
Another procedure currently under study is injecting adult stem cells at the time that an angioplasty procedure is performed to stop a heart attack in progress. These stem cells are taken from the heart patient’s bone marrow and injected into the heart, with the hoped for outcome of generating new, healthy heart tissue and improving long-term heart functioning.
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The Future of Stents
A stent is a tiny, metal mesh tube that is implanted in an artery wall during an angioplasty procedure. Stents were developed to solve a problem sometimes encountered with angioplasty: the artery would collapse after a blockage had been cleared. The stent is a permanent medical device that acts as a scaffold to keep the artery open. Stents currently are in one of two categories: bare metal or drug eluting (coated). Bare metal stents are the original stents and newer generation ones are still used today. Drug-eluting stents were designed to prevent a problem sometimes encountered with bare metal stents: restenosis – growth of scar tissue within the stent.
Like angioplasty, the near-term future of stents is focused on finding methods for treating blockages in flexion points in arteries – locations where arteries bend. Current generations of stents risk collapse in places of flexion.
While generations of stents now available in the United States are permanent medical devices that become embedded within the artery wall that may one day change. A bioabsorbable stent – one that is able to be absorbed by the body -- was recently approved for use in Europe. Bioabsorbable stents allow time for the artery wall to heal before being metabolized by the body and “disappearing.” These stents, in addition to other possible benefits, hold out the promise of making long-term medical therapy (medication) to prevent blood clots (thrombosis) from forming in the stent unnecessary. Bioabsorbable stents are still being studied and are not yet available in the United States.
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FDA Approval Process
New medical devices must be approved by the Food and Drug Administration (FDA) before they can be used in the United States, even if they are already in use in other countries. The FDA approval process is designed to establish the safety of medical devices before they are available on the U.S. market. For more about how an innovative technology becomes an approved medical device, see “From the Lab to a Patient’s Bedside: The Innovation Pathway for New Medicines and Devices.”
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