Stent

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It has been suggested that Stent Graft be merged into this article or section. (Discuss)

For people named Stent, see Stent (surname).

Endoscopic image of self-expanding metallic stent in esophagus, which was used to palliatively treat esophageal cancer.

Endoscopic image of biliary stent seen protruding from ampulla of Vater at the time of duodenoscopy

In medicine, a stent is either an expandable wire form or perforated tube (conventionally perforated by means of laser cutting) that is inserted into a natural conduit of the body to prevent or counteract a disease-induced localized flow constriction.

1 Applications
- 1.1 Problems
2 Etymology
3 Therapy: Stent implantation versus Coronary bypass surgery
4 See also
5 External links

[edit] Applications

The main purpose of a stent is to counteract significant decreases in vessel or duct diameter. Stents are often used to alleviate diminished blood flow to organs beyond an obstruction in order to maintain an adequate delivery of oxygen. Although the most common use of stents is in coronary arteries, they are widely used in other tubular structures, such as central and peripheral arteries and veins, bile ducts, esophagus, colon, trachea or large bronchi, ureters, and urethra.

[edit] Problems

One of the drawbacks of vascular stents is the potential development of a thick smooth muscle tissue inside the lumen, the so-called neointima. Development of a neointima is variable but can at times be so severe as to re-occlude the vessel lumen (restenosis), especially in the case of smaller diameter vessels, which often results in reintervention. Consequently, current research focuses on the reduction of neointima after stent placement. Considerable improvements have been made, including the use of more bio-compatible materials, anti-inflammatory drug-eluting stents, resorbable stents, and others. Fortunately, even if stents are eventually covered by neointima, the minimally invasive nature of their deployment makes reintervention possible and usually straightforward.

[edit] Etymology

The origin of the word stent remains unsettled. The verb stenting was used for centuries for the process of stiffening garments (a usage long obsolete, per the OED) and some believe this to be the origin. Others attribute the noun stent to Jan F. Esser, a Dutch plastic surgeon who in 1916 used the word to describe a dental impression compound invented in 1856 by the English dentist Charles Stent (1807–1885), which Esser employed to craft a form for facial reconstruction. The full account is described in the Journal of the History of Dentistry. [1] According to the author, from the use of Stent's compound as support for facial tissues grew the eventual use of stent to open various bodily structures.

[edit] Therapy: Stent implantation versus Coronary bypass surgery

Coronary heart disease (CHD) is a major cause of morbidity and mortality throughout the world, and both surgical revascularisation (coronary artery bypass grafting, CABG) and percutaneous coronary intervention (PCI) are established treatment options. The rapid developments in both surgical and percutaneous techniques have been such that the choice of the optimum revascularisation strategy is changing, often without an established evidence base; this is particularly true in complex conditions including patients with three-vessel and left main stem anatomy. The widespread use of drug eluting stents has resulted in a significant reduction in patients referred for CABG although published data favours the surgical approach in this high-risk group.

The SYNTAX Trial [2] aims to explore the interface between treatment with CABG and PCI in patients with three-vessel and left main stem disease, comparing CABG using contemporary techniques and PCI using drug eluting TAXUS stents. The aim of the trial is to establish non-inferiority of PCI with CABG. The unique feature of the SYNTAX trial is the ‘all comers’ strategy. A team comprising a cardiac surgeon and an interventional cardiologist assesses each patient; if equivalent revascularisation is applicable using both techniques, the patient is accepted for randomization; if either CABG or PCI is deemed unsuitable for technical reasons or the presence of co-morbidities, then the patient is recruited into one of two parallel registries which will track these patients undergoing either CABG or PCI. The patient will not be included in the randomized cohort. 1800 patients will be randomized (1:1) between CABG and PCI. The primary end-point is a major adverse, cardiac and cerbrovascular event at one year. All patients will be followed for five years. Of the 1800 patients, 710 with left main stem disease will be randomized between CABG and PCI. In this sub-group, repeat cardiac catheterisation will be undertaken after the one-year primary endpoint to determine graft and native vessel patency (the Le Mans sub-study).

The SYNTAX Trial is one of the most important trials ever undertaken in the field of coronary revascularisation and will provide a rational basis for choosing the optimum revascularisation strategy in patients for many years to come.