A new treatment method that combines the advantages of angioplasty balloons and drug-releasing stents, and offers fewer risks, has been examined as a way to open clogged arteries.

The study, led my MIT researchers and published in the journal Circulation, outlines the new approach where a balloon is inflated in the artery for just a short period where it releases a drug that stops cells from building up and clogging the arteries over time.

Over the past several years, scientists have developed many mechanisms that can reopen clogged arteries like angioplasty balloons and metallic stents. These treatments are generally effective, yet there are some drawbacks, including the risk of side effects.

The drug-coated balloons in the current study are still being developed in the U.S. and do not yet have FDA approval. The study, which models the behavior of the balloons, may help scientists achieve the best performance and help regulators in analyzing their safety and effectiveness. Elazer Edelman, the Thomas D. and Virginia W. Cabot Professor of Health Sciences and Technology and senior author of the paper describing the study, said, “Until now, people who evaluate such technology could not distinguish hype from promise.”

Up to the 1970s, the general treatment method for patients with clogged arteries close to the heart was bypass surgery. Shortly thereafter, doctors used a much less invasive process of reopening arteries with angioplasty balloons. Angioplasty became the regular treatment for semi-clogged arteries, but it is not a long-term solution because the arteries may eventually become blocked again.

To avoid this, scientists made stents – metal, cage-like mechanisms that can make an artery remain open for a period of time. Although these stents work well, they also have issues: When put in, they cause an immune response that may trigger cells to build up near the stent, blocking the artery again.

The FDA approved the first drug-eluting stent for use in the U.S. in 2003. This type of stent released drugs that stop cells from building up in the arteries. Known as drug-eluting stents – they are now the first choice for treating blocked arteries, however they have some side effects.

Over time, the drugs can result in blood clots, which can lead to death. Patients who receive these stents also need to take blood clotting medications like Plavix or aspirin.

Lead author of the paper Vijaya Kolachalama says:

“We’re trying to understand how and when this therapy could work and identify the conditions in which it may not. It has its merits; it has some disadvantages.”

The drug-coated balloons are administered via a catheter and inflated at the narrowed artery for 30 seconds or a bit longer. During this time, the balloon coating that includes a drug like Zotarolimus, is released by the balloon. The properties of the coating allows the drug to be absorbed in the body’s tissues. When the medication is released, the balloon is taken out.

In this study the investigators aimed to rigorously categorize the properties of the drug-coated balloons. After conducting these experiments in tissue grown in the lab and in pigs, they formed a computer model that details the dynamics of drug release and distribution.

The researchers discovered that the following factors can impact how long the drug stays at the injury site and how successfully it opens the arteries:

  • size of the balloon
  • duration of delivery time
  • composition of the drug coating

An important result is that when the drug is released, some of it sticks to the lining of the blood vessels. After a while, the medication is gradually released back into the tissue, accounting for why its effects last longer than the first 30-second release period.

Kolachalama says:

“This is the first time we can explain the reasons why drug-coated balloons can work. The study also offers areas where people can consider thinking about optimizing drug transfer and delivery.”

The authors plan to analyze further how blood flow affects drug delivery, several different drugs and drug coating compositions, and how the balloons behave in different kinds of arteries.

Written by Kelly Fitzgerald