• Overview

Stents are tubes made of plastic or metal or any other biocompatible material that are inserted into certain passageways in the body to allow free movement of various substances through the pathway. In certain cases such as of problems bile drainage from the liver due to ascending cholangitis  as a result of obstructing gallstones.

• Usage Sites

Stents are most commonly used in the coronary artery. This is done to regulate blood flow which is hampered due to problems such as deposition of fat along the arterial walls, hardening of the arterial walls, etc. The stent is placed in the artery during a procedure called angioplasty.

Stents are also used in the carotid , iliac and femoral arteries. Uretal stents are used for urine drainage in cases where the functioning of the ureters – which are tubes connecting the urinary bladder to the urethra , are affected.

A stent may also be passed through the penile and prostatic urethra. It is known as prostatic stent.

Stents are also used in the esophagus when swallowing food becomes difficult due to esophageal cancer.

• Risks and drawbacks

Stenting like any other medical procedure comes with it’s own set of drawbacks and risks. Placement of a stent in the body can lead to formation of clots. As a result , the patient has to be put on various blood thinning drugs such as warfarin or aspirin.

Scar tissue(plaque) can also form along the walls leading to narrowing of arteries. This can lead to narrowing of arteries . This condition is called restenosis.

Another complication is a condition called thrombosis. In this condition , formation of blood clots is seen within the stent after one year of placement.

• Types

Stents made of bare metals are known as First Generation Stents. A major drawback observed is that around 25% of coronary arteries treated with bare metal stents close up again usually in about 6 months.

Hence the patient is treated with the appropriate drugs. This results in the reduction of failure rates to less than 10%. The need for replacements is reduced considerably among the diabetic population.

Stents made of plastic and other biocompatible materials are known as Second and Third generation stents. The balloon expandable stent is the stent that is commonly used now.

• Market Value

The costs vary from region to region and also depend on the type required. However in recent times, researchers have been coming up with more long lasting and affordable stent models. The consulting firm Global Data stated that the global market for coronary stents is estimated to go up to $5.6 billion by 2020.

• Recent developments and scope in the future

In 2016 , the FDA approved a new type of stent made up of  a special polymer that eventually dissolves into the body. It releases a drug called everolimus which limits the growth of scar tissue .

New Second and Third generation stent designs are being developed in clinical trials.

One such model which is being developed has a covering that delivers an anti-restenosis drug for months and then becomes a bare metal stent.

Another version is supposed to be absorbed by the body after it has sufficiently widened the pathway and disappears completely