Restenosis is repeated occurrence of stenosis. Stenosis is narrowing of the blood vessel which obstructs easy flow of blood through it. Usually restenosis occurs in artery or a large blood vessel which had been cleared of the blockage. It is a major complication of percutaneous coronary intervention procedure. Procedures mainly used for vessel damage caused by atherosclerosis include cardiac surgery and angioplasty.
Angioplasty is frequently used interventional technique for removing blockage of a vessel since mid 1980’s. However, at least 50 percent of people after the procedure experienced symptoms of blockage caused due to restenosis within few months or years.Later on use of stent reduced the occurrence but it did not completely stop.
Various risk factors have been identified, some related to genetics and other acquired factors such as diabetes, hypertension and smoking. Restenosis may or may not produce symptoms. When present, symptoms include chest pain (angina) or they may also suffer minor or major heart attack.
Causes And Risk Factors Of Restenosis
When a section in the blood vessel is blocked it needs to be opened with angioplasty procedure or with a stent (mesh tube). Restenosis may develop after the opened artery becomes narrow again.This may develop due to many factors. However, the main pathophysiology underlying it is that of an inflammatory process.
Angioplasty in the vessel causes response in two stages. The first stage is immediate after trauma in the blood vessel. A clot is formed and it prevents proper flow of blood. The second stage takes place after 3 to 6 months after the intervention. It occurs due to proliferation of the cells in the smooth muscle of the arterial wall. The cells can also respond to the stent perceiving it as a foreign body. This may further narrow the artery.
The most important risk factors are:
- Diabetes mellitus
- Healing process is delayed.
- Hypersensitivity to the stent product. Hypersensitivity may develop in stainless steel stents that release nickel and molybdenum. However, new variety of stents made up of cobalt and chromium have significantly reduced hypersensitivity.
- Mechanical causes may also cause restenosis. This may include under expansion of stents, improper placement of the stent to the vessel wall, impairment of drug eluting property of the stent faced due to difficulty in proper implantation of the stent.
Symptoms And Treatment Of Restenosis
Restenosis usually occurs within 3 to 6 months after angioplasty and placement of stent. There is more likelihood of its occurrence when a metal stent is used. Drug eluting stents have lesser risk of restenosis. This is due to coating of a drug in drug eluting stents. It is released slowly which prevents formation of clot and scar tissue underneath the vessel wall.
Patient with restenosis may experience symptoms or he may remain asymptomatic even with restenosis. When symptoms are present it includes pain in chest with activity or without activity, shortness of breath, increased tiredness.
Treatment: With advent of drug eluting stents the incidence of restenosis has greatly reduced. However, it has not completely eliminated. If restenosis develops and produces symptoms of angina then the appropriate treatment is to repeat angioplasty and placing a second stent at the same place of the first one. Medical therapy includes use of anti coagulant medicines. CABG (coronary artery bypass graft) is also an option in some cases.