The administration of stents in medical care has been extensive in the past few years. Stents are tiny web like structures made with wire; often with a mesh-like appearance. They are used in expanding a narrowed blood vessel in conditions such as coronary artery disease. The mechanical support provided by the stent plays a significant role in preventing the reoccurrence of arterial blockage. Stents are predominantly administered in arteries associated with the brain, thorax, abdomen, coronary and peripheral organs.
The incorporated stent exerts an outward pressure to open the lumen in dilating the blood vessel and the pressure exerted has to be monitored carefully during the procedure. There are many different types of stents available and all of them have specific parameters based on which they have been classified as avascular, non vascular, coronary and peripheral types. Stents are engineered to have low elasticity and high stress capability. Some stents are balloon incorporated for their release mechanism and others are delivered and expanded.
These type of stents are administered in conditions such as atherosclerosis, aneurysm and coronary artery diseases. Many procedures such as the balloon valvuloplasty, :Angioplasty prefer the incorporation of stents that can be expanded by using a balloon catheter in the region of blockage. With this, the risk of arterial re- narrowing is avoided. Application of coronary stents have become very extensive in contemporary cardiac procedures.
These stents are used in portal vein stenosis, a condition in which the artery supplying blood to the liver, pancreas and the abdominal region is obstructed. In most cases these obstructions occur in malignant tumors or cancers of the hepatic or biliary region. Many studies indicate that the administration of portal stents have facilitated significant progress in the functionality of the liver in relieving portal hypertension.
Non vascular stents
The use of stents was initially limited to vascular diseases. Recent studies indicate the increase in the use of stents in nonvascular conditions are related to gastrointestinal system, urinogenital system and also in the tracheo bronchial region.
Drug eluting stents
These stents are also used in cardiac conditions. They have a specific role in the treatment of coronary artery disease. They are used to reduce the inflammation and cell proliferation in the artery when the stent is introduced.
These stents are used predominantly to clear the obstruction that is present in the urethral passage . In most cases it is administered in renal or urethral malignancies to clear the urine. The only discomfort in these stents are that they tend to cause itching and irritation.
Restenosis refers to the re-narrowing of the coronary artery after an Angioplasty procedure. It literally means reoccurrence of the stenosis (narrowing of the blood vessel). Restenosis occurs within 3-6 moths in 40-50% of people who have undergone an Angioplasty.
During the procedure of angioplasty a balloon is inserted into the blocked artery and inflated so as to allow the blood to flow normally to all portions of the heart. During this procedure the surrounding tissues undergo trauma and become susceptible for damage. Restenosis may set in during thrombosis or due to fresh tissue growth at the site of the surgery. Restenosis does not indicate progression of the heart disease but may be an indication that the body's immune system is responding to the injury caused during angioplasty.
Modern medicine has seen the use of stents to keep the artery open. Usage of stents has brought down restenosis considerably. Usage of drug-eluting stent allows slow seepage of medication that reduces proliferation of cells thus reducing re-clogging.
Restenosis causes and treatment
Restenosis is mainly caused due to a surgery that unblocks or widens a blood vessel. Treatment depends on the clinical condition:
Ureteroscopy is a common urological procedure administered in patients having urinary tract and bladder related disorders. Ureteroscopy is recommended for patients having kidney stones. The movement of the renal stones is monitored by urologists. Ureteroscopy is a minimal invasive endoscopic procedure predominantly involving the urethra, upper urinary tract and the urinary bladder.
A flexible or rigid form of telescope is passed through the urethra in order to view the affected region. The procedure is performed under general or spinal anesthesia. The telescopic examination of the ureter and associated organs reveals the exact location of the stone and also other disorders of the system. Other diagnostic tests such as X-rays, CT scan, EKG along with laboratory parameters like urinalysis and complete blood count also help in the effective determination of the underlying condition. This technique is usually followed by the other associated procedures such as lithotripsy in which laser beams are administered to the affected region to dissolve the calculi(stone) or to clear urinary tract strictures. The entire procedure may last from 30 minutes to three hours and patients are advised to stay in the hospital for a day.
The urologist uses the uterescope to remove small kidney stones while larger stones need to be broken up before removal. A kidney stone that has escaped from the kidney and got stuck in the ureter can be pushed back into the kidney. Here it has to be broken into smaller pieces to aid removal. A stent is usually left in place to allow the kidneys to pass the urine to the bladder. This is kept for a few days in case there is swelling and subsequent difficulty in draining the kidney of the urine.
Complications and risk factors
Hematuria happens because of the insertion of the ureteroscope. It usually subsides within 3 days. Antimicrobial therapy is given if hematuria is followed by an infection. Other possible complications are:
Stent associated pain
Perforations caused because of stents
Lower back pain
Urethral stricture or perforation
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Bibliography / Reference
Collection of Pages - Last revised Date: March 4, 2021