Stents and related terms: a brief history

Advancing Toward 3D Printing of Bioresorbable Shape Memory Polymer Stents

Stents have evolved significantly since their introduction to the medical field in the early 1980s, becoming widely used in percutaneous coronary interventions and following nephrological procedures. However, the current commercially available stents do not degrade and remain in the body forever, leading to problems like restenosis in cardiovascular applications or requiring removal procedures in ureteral applications. Efforts to replace metal with resorbable materials have largely been halted after the commercial failure of and safety concerns elicited by Abbott's Absorb stent in 2017. Industry continues to use common polymers such as poly(l-lactide) (PLLA) and polycaprolactone (PCL) for biomedical products, but due to the weak mechanical properties of these bioresorbable materials in comparison to metals, these devices have struggled to accomplish the goals set, increasing risk of thrombosis. 3D printing stents using bioresorbable and shape memory materials could provide a method of patient-personalized production, remove the need for balloon expansion, and limit stent migration, thus bringing a new age of stent technology. The investigation of a range of 3D-printable and bioresorbable shape-memory polymers can provide solutions to the shortcomings of previously explored bioresorbable stents and revitalize the medical device industry efforts into advancing stent technology.

["We're going to place a ureteral stent …" : Development and use of the terms stent and splint by German-speaking urologists]

The use of eponyms has a long history in medicine. But it is a rare case that a term not associated with a procedure or an anatomical description has come into use. The terms "stent" and "splint" in German and English used as a verb and a noun are a typical example. The coronary stent was named after Charles Thomas Stent (1807-1885). Charles Theodore Dotter (1920-1985) was the one who introduced the eponym into the literature of angiography in 1983. The change in urology occurred after an article of Willard Goodwin especially in the English literature but did not come into constant use in the German language.

New developments in ureteral stent design, materials and coatings

Ureteral stents are used in a variety of urological diseases and procedures. The majority of patients with indwelling ureteral stents experience bothersome symptoms and are at increased risk for urinary tract infection. Stent encrustation and the associated complications can also result in significant patient morbidity. The development of new stent designs using novel biomaterials, stent coatings and drug-eluting technologies are being applied to reduce the disadvantageous features of ureteral stents.

Technology insight: Novel ureteral stent materials and designs

Ureteral stents are an important tool for aiding upper urinary tract drainage, but can cause significant patient morbidity. Common problems include stent-induced pain, hematuria, dysuria, infection, and encrustation. From a urologist's perspective, stents must be easy to maneuver in the urinary tract, radiopaque, and affordable. Since the development of the modern day stent in 1978, stents have evolved to include softer biomaterials that are more resistant to encrustation and infection. An ideal biomaterial is one that is not affected by its environment and does not elicit reactive changes in surrounding tissues. To date, the ideal biomaterial or stent does not exist. This review discusses developments that address the issues of infection, biofilm formation, encrustation, and patient comfort. Stent materials including polyurethane, silicone, biodegradable substances and new combination polymers are reviewed, in addition to novel stent coatings such as heparin, hydrogel, and silver nitrate. Ureteral stent technologies currently lag behind vascular stents, particularly drug-eluting stents, but new developments will continue to improve these essential urological tools.

The use of stents in contemporary urology

PURPOSE OF REVIEW

Ureteral stents are a mainstay of today's urological armamentarium. This review critically evaluates the recent literature and provides a concise summary of the use of stents in urology today. While stents are used in many reconstructive urologic procedures, this review focuses on the use of stents in urolithiasis as it pertains to ureteroscopy, shockwave lithotripsy, and ureteropelvic junction obstruction.

RECENT FINDINGS

Ureteral stents are associated with irritative symptoms, hematuria, infection, and encrustation. A new validated quality of life and impact questionnaire has been developed and has shown that 76% of patients suffer at least some type of morbidity related to the stent. Many studies in the recent literature have re-examined our use of stents today. For example, concepts regarding stenting following ureteroscopy, before shockwave lithotripsy, and following endopyelotomy have undergone an evolution based on the results of randomized, prospective studies.

SUMMARY

The ureteral stent is an invaluable urological tool and its indications are evolving as are new stent technologies to improve patient care and comfort.

Ureteric stenting 25 years on: routine or risky?

BACKGROUND

Ureteric stents have been used in urological practice for over 25 years and in many cases have become almost routine. The purpose of the present review is to highlight the uses, complications and risk management issues associated with their use.

METHODS

An extensive literature review was conducted and knowledge from past experience was accessed to give a summary of past and current ureteric stent use in urology.

RESULTS

Broadly, there are stone and non-stone indications for stenting. Complications may range from the commonly experienced 'stent syndrome' to the medico-legal dilemma of the forgotten stent. Risk management must be applied to all uses of stenting to minimize complications and achieve best practice.

CONCLUSION

Although almost routine in many areas of urological practice, the complications and implications for risk management of ureteric stenting cannot be ignored.

Ureteral stents and their use in endourology

Ureteral stents have assisted urologists in the performance of surgery of the urinary tract for many years. They can have both diagnostic and therapeutic value, but are used most frequently as adjuncts to endoscopic or minimally invasive procedures. This review provides an update of the current uses for ureteral stents, technology of biomaterials, complications associated with indwelling ureteral stents and the future of stents in urology.