Cath Lab Digest

The ebb and flow of medical advancement
The field of vascular intervention, particularly percutaneous, is a rapidly expanding field. With a decrease in complication and readmission rates and procedural costs coupled with an increase in success and patient satisfaction rates, the number of treatments offered and the variety of diseases targeted is growing at a quickening pace. The increasing complexity of the field is reflected by its multidisciplinary nature (one need not look further than the inspiration behind Vascular Disease Management). Relatively new procedures rapidly replace traditional ones that have been the standard for decades. The impetus is not surprising, in circumstances where there are two procedures with comparable measures of success), the procedure with the lesser amount of body invasion will be preferable (at the least, by the patient).

The enthusiasm for adopting new procedures must be tempered, regardless of how promising they appear, because they are “new,” and often “unproven.” There is a well-established process by which new procedures enter clinical practice. They must first work in theory and then be extensively proven in animal models. Various measures of success and failure must be meticulously recorded and then followed by a small clinical trial in human patients. If successful, additional, more extensive trials are conducted. Eventually, large scale trials are performed, followed by meta-analyses combining the results of many trials.

Many factors play into the success of a new technology, such as the obvious (success rates, complication rates), the discrete (cost, patient satisfaction, procedural time and difficulty), and the subtle (politics). At any point, a new technology can be squashed. If and once a new technology is proven superior, however, physicians have a duty to adopt it. A physician today would be unlikely to get away with practicing many of the procedures that were status-quo 50 years ago.

Disruptive versus sustaining technologies
Clayton Christensen described technology as being either “sustaining” or “disruptive”.¹ A sustaining technology is one that incrementally builds and improves upon existing technologies. An example is drug-eluting stents, which built upon an existing technology, regular stents. Another example is many of the advances in cardiac surgery, particularly the studies on cardiac protection during coronary artery bypass surgery.² In many ways, this can be seen as refining existing technology.

This is in contrast to a “disruptive technology,” which is an entirely new and radically different technology that eventually overturns the previously dominant technology. An example of a disruptive technology is balloon angioplasty,² which overtook much of the market previously held by the cardiac surgeons. An example of a technology that may become a disruptive technology is the percutaneous heart valve replacement. Disruptive technologies are often initially inferior to existing technologies by traditional performance measures but come to dominate by either filling vacant markets that the existing technology could not fill, or by incremental improvements until it is the superior technology. Disruptive technologies may be superior in success rate, cost, efficiency, simplicity and/or safety.

Uterine artery embolization: a disruptive technology.
Uterine artery embolization (UAE) should be considered a “disruptive technology.” The existing technology was the hysterectomy. Various sustaining technologies improved upon the original hysterectomy procedure, including medication regimen, technique and type of hysterectomy, and most recently, method of hysterectomy (i.e., from abdominal- to vaginal- to laparoscopically-assisted- and now to total-laparoscopic hysterectomy.^3,4 Then, the first transcatheter embolization of the uterine arteries for symptomatic leiomyomata was reported by Ravina and colleagues in 1995.⁵ Initially, the complication rate was not particularly good, and certainly not better than hysterectomy.⁵ But as the procedure was developed and refined, its popularity quickly grew, so that by the year 2000, over 10,000 UAEs had been performed. UAE had also made it into the popular press, particularly after Condoleeza Rice underwent the procedure, with reports on major media publications and television shows (e.g., Newsweek,™ NBC Nightly News,™ 20/20,™ and USA Today Weekly™). The procedure had rapidly established itself as a viable treatment option for women with uterine fibroids and had become a major focus of research among interventional radiologists.^6–9

Uterine artery embolization: past the validation period.
As a result of the intense amount of interest in UAE as a treatment for uterine fibroids, a large amount of time, effort and money has been spent on researching the procedure. While the old stand-by, the hysterectomy, is a major operation with a complication rate between 17 and 23%,¹⁰ UAE has a technical success rate over 95%, a procedural complication rate of 5%¹¹ and a short- and mid-term success rate of approximately 90%.¹² Furthermore, due to the minimally-invasive nature of the procedure, the hospital stay is much shorter: UAE can be performed as an inpatient procedure with a hospital stay of 1–2 days,¹³ or as an outpatient procedure, with a post-procedural stay of 6–8 hours.⁷ UAE also allows for post-treatment pregnancy.¹⁴ As a result of a combination of these factors, UAE likely leads to high satisfaction rates of approximately 90%.^7,13,15