Biomedical Research in Stents

On a July night almost ten years ago, my grandfather woke up with massive pressure in his chest. He shook my grandmother awake, and told her he felt like there was an elephant sitting on top of him. Recognizing the symptoms of a heart attack, my grandmother immediately drove him to the hospital in their small mountain community. Though his electrocardiogram showed only minor changes, the doctor was suspicious of my grandfather’s symptoms and had him airlifted to Phoenix for treatment. In the Phoenix hospital a battery of tests confirmed that my grandfather had suffered a massive heart attack. He had extremely high enzyme levels, an ejection fraction of only twenty-five percent, and a massive clot on the inside of his heart wall. Fortunately for our family, the doctors were able to treat his condition with drugs and a stent, and my grandfather recovered. Since my grandfather’s major heart attack, he has continued to suffer from progressive heart disease and now has stents in several coronary arteries. Without stenting, my grandfather would not be alive today.

A stent is a wire mesh tube, and stenting is a medical technique, often used in conjunction with angioplasty, that reopens blocked arteries, particularly those of the heart (5). The procedure is performed in a catheterization laboratory under local anesthesia. To place the stent, a catheter is inserted into the patient via the femoral artery in the groin. The catheter is then guided to the coronary artery, where a dye visible by x-ray is injected through the catheter to guide the procedure. A guide wire passes through the catheter and into the blockage, at which point most patients undergo a balloon angioplasty to push the blockage to the walls of the artery. Next, a stent which has been collapsed around a balloon-tipped catheter is advanced to the narrowed area of the artery. The balloon is the inflated, pressing the stent against the walls of the artery. After the balloon-tipped catheter is removed from the body, the stent remains permanently affixed to the once-blocked area of the coronary artery. The stent becomes covered with a layer of arterial tissue between four and six weeks after its insertion and, ideally, prevents another blockage of the artery.

Stents are becoming increasingly useful. Aside from treating arteriosclerotic plaques in the coronary arteries, they are also used to reopen arteries in the limbs and treat aneurisms. One of the newest procedures is carotid artery stenting. This treatment prevents stroke by eliminating dangerous plaques in the arteries that supply the brain with blood. Another developing stent technology is called the drug-eluting stent, which slowly releases chemotherapeutic drugs. This type of stent is designed to reduce the risk of restenosis, or reclosing of the artery, which is one of the most frequent complications associated with stenting. A similar technology is the DNA eluting stent. This stent uses gene therapy to prevent the regrowth of arterial tissue in the stent, and thus prevent the reblockage of the artery.

None of these life-saving advances would be possible without animal research. Innovative but unrefined new technologies, and new applications for old technologies, can rarely be developed using human subjects alone because the risks of the treatment are unknown. An experimental treatment might produce horrific side effects in a human subject; therefore, treatments must first be refined and improved on animal subjects. For instance, DNA-eluting stents were initially tested in vitro using rat aortic muscle and in vivo using pigs. The technology could not ethically be tested in human beings without this initial step. What if the DNA-eluting stents had provoked an autoimmune response, or some other side effect? Animal testing allows a scientist to explore and refine the potentials and pitfalls of a technology without endangering human beings. Furthermore, testing prototype treatments on sick individuals would exploit their vulnerability and desperation. Without animal testing to weed out the ineffective and/or dangerous treatments, hope might lead sick people to submit to treatments that, at worst, could be deadly. Animal testing protects both human subjects and the ethical integrity of biomedical scientists.

Biomedical research has had an enormous impact on my life and the lives of my loved ones. It developed the stents that saved my grandpa’s life, and continues to refine the technology of stenting to save other lives. Animal research makes this kind of progress possible. Without animal research, the quality of life we experience today would not be nearly so high.