Memokath Stent Research Articles

Use of Memokath 051 Metallic Stent in the Management of Ureteral Strictures: A Single-Center Experience

Introduction: Memokath 051® represents a nickel-titanium stent that has been used to treat patients with incurable ureteral strictures. In the current study we present our experience in using this technique. Materials and Methods: Between 2003 and 2008, 19 metallic stents were placed in 13 patients. All of them had been previously treated by using JJ stents or dilatation. The etiology was benign in 10, while in 3 patients malignancy was involved. The mean age was 60.7 years. Mean stricture length was 3.2 cm while the median stent length was 6 cm. No severe complications were noticed postoperatively. Mean follow-up was 14.3 months. Results: Six patients (46%) experienced a satisfactory result after first insertion. Stent migration was observed in 6 patients and in 3 it was replaced successfully. One patient was offered a simple nephrectomy due to a poorly functioning kidney. Eventually, 10 of 13 patients (77%) had a successful outcome after the final stent insertion. Conclusion: Memokath stents suggest a possible alternative in treating chronic/recurrent ureteral strictures. Their most important disadvantage seems to be migration. Their role in endourological practice remains to be validated.

1086 THERMO EXPANDABLE SEGMENTAL METAL URETERIC STENTS IN THE MANAGEMENT OF URETERIC STRICTURES: A SINGLE CENTRE EXPERIENCE FROM THE UK

You have accessJournal of UrologyTechnology & Instruments: Robotics/Laparoscopy/Ureteroscopy III1 Apr 20101086 THERMO EXPANDABLE SEGMENTAL METAL URETERIC STENTS IN THE MANAGEMENT OF URETERIC STRICTURES: A SINGLE CENTRE EXPERIENCE FROM THE UK Konstantinos Moraitis, Tamer El-Husseiny, Hassan Wazait, Junaid Islam, Junaid Masood, and Niels Buchholz Konstantinos MoraitisKonstantinos Moraitis More articles by this author , Tamer El-HusseinyTamer El-Husseiny More articles by this author , Hassan WazaitHassan Wazait More articles by this author , Junaid IslamJunaid Islam More articles by this author , Junaid MasoodJunaid Masood More articles by this author , and Niels BuchholzNiels Buchholz More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.2283AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES JJ stents revolutionised the minimally invasive management of benign and malignant ureteric strictures but have significant side effects such as encrustation, pain, infection, reflux, decreased ureteric peristalsis and migration as well as LUTS. More recently metallic stents have been introduced to try and improve these symptoms and avoid frequent stent exchanges. We present our experience of the Memokath 051 TM (PNN Medical, Denmark); a new generation thermo-expandable segmental nickel-titanium alloy metallic stent in the management of benign and malignant ureteric strictures. METHODS Increasingly over the last 5 years, we place ureteric Memokath 051 TM stents in patients wishing minimally invasive therapy and referred with ureteric strictures. The stent has a shaft diameter of 10.5 Fr and its fluted proximal end expands to 20 Fr. Available lengths are 30, 60, 100, 150, and 200 mm. Follow-up data looking at performance and complications is prospectively collected and analysed. RESULTS 89 patients (48 females, 41 males) (mean age: 58 years) have had 124 stents placed for a total of 104 strictures. 64% of strictures are benign and 36% are malignant. Peri-ureteric fibrosis (15%), idiopathic (18.6%) and iatrogenic (9 %) strictures represent the most common benign causes. 6 (5.4%) ureteric memokaths were inserted in anastomotic strictures in transplanted kidneys. Malignant strictures were mainly caused by gynaecological (35.1%), bowel (24.3%) and prostate (18.9%) malignancy. Over a mean follow-up of 19 months (range: 1-61), 71% of patients have their original stent in situ, which is functioning well with no signs of upper tract obstruction. Over this period, 17 patients have had spontaneous resolution of their benign stricture. The most common complication in our series is stent migration, occurring in 18.5% of patients requiring either adjustment of the stent position or removal and insertion of a new stent, followed by infection (11.3%) and stent encrustation/blockage (5.6%). CONCLUSIONS Our results show that ureteric memokath stents are effective in the minimally invasive management of benign and malignant ureteric strictures. As they do not require routine exchange, are relatively resistant to encrustation compared to JJ stents, are well tolerated by patients in our experience and easy to remove, there are potential significant benefits for patients, and financial savings for hospital trusts. Larger scale studies are necessary to further evaluate the role of these stents. London, United Kingdom© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e422-e423 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Konstantinos Moraitis More articles by this author Tamer El-Husseiny More articles by this author Hassan Wazait More articles by this author Junaid Islam More articles by this author Junaid Masood More articles by this author Niels Buchholz More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A Novel Thermo-Expandable Ureteral Metal Stent for the Minimally Invasive Management of Ureteral Strictures

We assess the safety, efficacy, and cost of the novel long-term indwelling thermo-expandable Memokath ureteral stent for the management of malignant and benign ureteral strictures. Since October 2004, we treated 73 patients (34 men), ages 23 to 84 years (mean 57.7) with 86 ureteral strictures (13 bilateral) with the Memokath 051 stent. The causes of the strictures were benign in 55 cases and malignant in 31 cases. Follow-up included radiography, renal ultrasonography, and renography if needed after 2 weeks, 3 months, and then every 6 months. The mean operative time was 23 minutes, while the mean hospital stay was 1.5 days. The average indwelling time of an individual Memokath was 11.2 months. After a mean follow-up period of 17.1 months, there were 68 stents in situ. In 12 cases, spontaneous resolution of the ureteral stricture was revealed after a mean indwelling time of 9 months. The remainding six cases were treatment failures. In 15 cases, because of late complications, a Memokath exchange took place after a mean period of 18 months. A total of 26 complications were revealed after the insertion of 102 Memokath stents. These included six cases of urinary tract infections; 15 stent manipulations were needed because of stent dislodgement, and 5 stents were removed because of encrustration and blockage. In the long term, the overall costs for the Memokath treatment and follow-up were considerably less than with the conventional Double-J stent. The ureteral Memokath stent is a promising, safe, and efficient treatment option for the minimally invasive management of both benign and malignant ureteral strictures.

Transurethral Sphincterotomy

No AccessJournal of UrologyOpposing Views1 Apr 2009Transurethral Sphincterotomy Inder Perkash Inder PerkashInder Perkash More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2009.02.014AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "Transurethral Sphincterotomy." The Journal of Urology, 181(4), pp. 1539–1540 References 1 : Use of the Memokath for detrusor-sphincter dyssynergia after spinal cord injury—a cautionary tale. Spinal Cord1998; 36: 39. Google Scholar 2 : Long-term follow-up study of intraurethral stents in spinal cord injured patients with detrusor-sphincter dyssynergia. Spinal Cord2007; 45: 621. Google Scholar 3 : The use of the Memokath stent in the treatment of detrusor sphincter dyssynergia in spinal cord injury patients: a single-centre seven-year experience. Eur Urol2003; 43: 539. Google Scholar 4 : Detrusor-sphincter dyssynergia and detrusor hyperreflexia leading to hydronephrosis during intermittent catheterization. J Urol1978; 120: 620. Link, Google Scholar 5 : The various types of neurogenic bladder dysfunction: an update of current therapeutic concepts. Paraplegia1990; 28: 217. Google Scholar 6 : Contact laser sphincterotomy: further experience and longer follow-up. Spinal Cord1996; 34: 227. Google Scholar 7 : Transurethral sphincterotomy provides significant relief in autonomic dysreflexia in spinal cord injured male patients: long-term followup results. J Urol2007; 177: 1026. Link, Google Scholar 8 : Use of penile prostheses to maintain external condom catheter drainage in spinal cord injury patients. Paraplegia1992; 30: 327. Google Scholar 9 : Bladder leak pressure: the measure for sphincterotomy success in spinal cord injured patients with external detrusor-dyssynergia. J Urol1998; 159: 493. Link, Google Scholar Surgical Service, VA Palo Alto and Stanford University, Stanford, California© 2009 by American Urological AssociationFiguresReferencesRelatedDetails Volume 181Issue 4April 2009Page: 1539-1540 Advertisement Copyright & Permissions© 2009 by American Urological AssociationMetricsAuthor Information Inder Perkash More articles by this author Expand All Advertisement PDF DownloadLoading ...

経直腸超音波検査とＸ線透視を併用した形状記憶合金製尿道ステント（ＭＥＭＯＫＡＴＨ）の留置

Intraurethral catheters are effective in the treatment of elderly patients with benign prostate hyperplasia (BPH) who have severe complications. However, it is not easy to measure the length of the prostatic urethra and to determine an appropriate location for the urethral catheter using only fluoroscopy, especially in patient with severe mid-lobe enlargement. We attempted to place a shape-memory alloy intraurethral catheter (MEMOKATH) by transrectal ultrasonography and fluoroscopy to measure the precise length of the prostatic urethra and to determine an appropriate location for an intraurethral catheter placement. Patients were given urethral infiltration anesthesia with 2% lidocaine hydrochloride jelly and placed in the supine position. Both transrectal ultrasonography and fluoroscopy were performed to observe the bladder neck, the apex of the prostate gland, and the prostatic urethra. Transrectal ultrasonography was shown to depict them more clearly than fluoroscopy. Transrectal ultrasonography was also shown to be more suitable than fluoroscopy for measuring the prostatic urethra length, as well as for accurately positioning the MEMOKATH stent, especially in cases of BPH with mid-lobe enlargement. The MEMOKATH stent was placed in 7 patients with BPH. Urethral catheters had been put in place in 6 of these patients because of urinary retention, and large amounts of residual urine were found in the remaining patient. Three patients had severe mid-lobe enlargement. All patients were able to urinate without much residual urine after the procedure. No severe complications were noted. Transrectal ultrasonography is useful for accurately placing the MEMOKATH stent, as it provides more objective and detailed anatomical findings than fluoroscopy.

Possible Role of Large Fluid Intake in Delaying Formation of Encrustations and, thereby, Prolonging Working Life of Memokath Stent for Nearly 14 Years in a Spinal Cord Injury Patient

The Memokath stent has been used in spinal cord injury patients as a reversible alternative to external urethral sphincterotomy, but the stent has a finite lifetime of <2 years before failure in the majority of patients. We report an unusual case of a spinal cord injury patient in whom memokath stent was functioning for almost 14 years. The long life span of the Memokath in this patient was probably due to this person's habit of drinking around 5 l of fluids a day. Large fluid intake resulted in high urine output and, consequently, deceased the risk of urine infections and delayed formation of encrustations around the stent. Although this case represents an unusual length of time for a Memokath stent to have been in place and functioning, caution should be exercised against the long-term use of Memokath stents. Memokath stents do not get absorbed into the mucosa unlike urolume stents and, therefore, are prone to stone formation. Further, Memokath stents have not yet been approved in the U.S. either for bladder outlet obstruction or detrusor-sphincter dyssynergia. This case is also a reminder to health professionals that if a tetraplegic patient, in whom a Memokath stent has been deployed for treatment of detrusor-sphincter dyssynergia, presents with autonomic dysreflexia, encrustations blocking the lumen of the stent or calculus formation around the stent should be considered as possible reasons for autonomic dysreflexia.

MP-07.16: Memokath stent implantation in urogenital system

MP-07.16: Memokath stent implantation in urogenital system

The thermo‐expandable metallic stent for managing benign prostatic hyperplasia: a systematic review

To systematically review published reports of the safety, effectiveness and durability of a self-expanding metallic prostatic stent (Memokath, Engineers & Doctors A/S Ltd., Denmark) in patients with benign prostatic hyperplasia (BPH) who are unfit for surgery. We systematically searched the Medline and Embase databases from 1992. The reference lists of included studies and the bibliographies of review articles were also searched. We contacted the manufacturer of Memokath for additional information. The primary outcomes were treatment failure (stent removal, replacement or repositioning) and urological symptom scores. Secondary outcomes were urodynamic indices and minor complications. Two reviewers independently assessed the methodological quality of the studies and extracted data. Data were synthesized using narrative techniques. In all, 14 case series described the use of the Memokath stent in 839 men with BPH. All patients were at high operative risk. Most studies were of poor quality with an inadequate follow-up. Treatment failure rates were 0-48% but the duration of follow-up was often unclear. Five studies reported International Prostate Symptom Scores and found reductions of 11-19 points after stent insertion. All seven studies that reported on maximum urinary flow rates found that these increased, and the four that described residual urine volumes found that these decreased. Minor complications were inconsistently reported. The Memokath stent can provide an effective treatment for BPH in men at high operative risk; it also appears to be safe, but inadequate follow-up does not allow firm conclusions on stent durability.

Thermo-expandable Intra-prostatic Stent in the Treatment of Acute Urinary Retention in Elderly Patients with Significant Co-morbidities

We assess the use of thermo-expandable intra-prostatic stent (Memokath, Engineers and Doctors A/S, Denmark) for the treatment of acute urinary retention (AUR) in men with significant co-morbidities for transurethral resection of prostate (TURP). We evaluate the pre- and post-operative complications, duration of stents in-situ and patients quality of life after the stent insertion. Patients with significant co-morbidities presenting with AUR were selected, who were unfit for TURP. The co-morbidities included ischaemic heart disease, congestive heart failure, and chronic obstructive pulmonary disease. The exclusion criteria were bladder tumour and atonic bladder. The Memokath stents were inserted using a flexible cystoscope under local anaesthesia. The patients were followed up at 3 and 6 months after the procedure and the ones who remained alive were asked to complete self-administered questionnaires and IPSS scores. Fifteen men with acute urinary retention were recruited for stent insertion with the mean age of 87 years. No peri-operative complications were recorded. Three patients died after the insertion with functional Memokath in-situ. Nine patients had good functioning stents post-operatively, and remain catheter free up to 30 months after the procedure. The mean duration of stent life was 18 months. Three long-term complications were detected, including stent migration and prostate overgrowth. The Memokath is a good option for frail elderly patients presenting with AUR. The procedure is safe and has minimal long term complications. The stent also provides a sustained good quality of life for patients and avoids the necessity of long term catheterisation.

Memokath® stents for the treatment of detrusor sphincter dyssynergia (DSD) in men with spinal cord injury: The Princess Royal Spinal Injuries Unit 10-year experience

Medical records review. To assess the effectiveness of the Memokath (Engineers and Doctors A/S, Denmark) thermosensitive stent as a 'nondestructive' means of reducing bladder outlet resistance by treating detrusor sphincter dyssynergia (DSD) of neurogenic bladder dysfunction associated with spinal cord injury. Spinal Injuries Unit, Sheffield, England. A medical records review was performed to examine our experience of Memokaths over the last 10 years. During this time, 29 patients with spinal cord injury (17 tetraplegic and 12 paraplegic) underwent stenting of the external urethral sphincter either for prevention of dysreflexic symptoms, high residual urine volumes and subsequent urinary tract infection (UTI) or for protection of the upper tracts. A total of 33 stents were inserted into 29 men (25-77 years) with suprasacral spinal cord injury. Initial results showed that the Memokath was effective in almost all for relief of dysreflexic symptoms and elimination of DSD on pressure flow urodynamics. However, to date, 30 of the 33 stents have been removed. The overall mean working life of the Memokath was 21 months. Four stents were removed electively and 23 for complications, which included stent migration (seven) and blockage (14). Single-ended stents were more prone to migration, which was rare after 1 year (1-13 months, median 3 months, mean 5.5 months). Stent blockage by encrustation or prostatic ingrowth did not occur before 12 months (12-45 months, median 30, mean 27.9 months). In selected patients, temporary, thermo-expandable (Memokath) stents are effective in the treatment of DSD. The 'working life' of a Memokath stent is 21 months; however, complications do occur which may necessitate removal. Our overall experience with Memokath stents was disappointing. In future, Memokath stents will only be inserted after careful consideration in patients with prior 'failed' transurethral sphincterotomy or with caution in patients suitable for reconstructive surgery.

Encrustation and Strength Retention Properties of the Self-expandable, Biodegradable, Self-reinforced L-Lactide-Glycolic Acid Co-polymer 80:20 Spiral Urethral Stent In Vitro

Encrustation of urological stents is a clinical problem. The chemical composition and surface properties of the devices have a marked effect on its incidence. The ability of the stent to prevent duct collapse depends on its compression strength, which decreases as degradation progresses. We have developed a new self-reinforced, L-lactide-glycolic acid co-polymer with a molar ratio of 80:20 (SR-PLGA 80/20), that is the SpiroFlow (Bionx Implants, Ltd., Tampere, Finland) stent. We compared the resistance to encrustation of the new stent material to that of 2 temporary metallic stents, Prostakath (Doctors and Engineers, Inc., Copenhagen, Denmark) and Memokath 028 (Engineers and Doctors A/S, Ltd., Kvistgård, Denmark). In addition, mechanical compression properties during degradation were investigated. For encrustation studies 7 mm segments of the test material of the SR-PLGA 80/20, Prostakath and Memokath stents were incubated in vitro in sterile artificial urine for 4 and 8 weeks, and the SR-PLGA 80/20 also for 12 weeks. After incubation the specimens were fixed in glutaraldehyde, critical point dried and coated with gold in sputter for scanning electron microscope analysis. Analysis was done at 100x magnification in 5 randomly selected areas per sample. Results are presented as a median percent of the whole analyzed area covered by encrustation in each tested material. For compression strength studies 20 mm pieces of manufactured SR-PLGA 80/20 spiral stent wire were similarly incubated in sterile artificial urine for 12 weeks. Measurements were made by compressing the specimens between 2 parallel planes at 2, 4, 6, 8 and 12 weeks. All analyses were made in triplicate. The areas covered by encrustation at 4 weeks were 8.01% for the Memokath, 1.49% for the Prostakath and 0% for the SR-PLGA 80/20. At 8 weeks the percent was 28.4%, 4.1% and 0.12%, respectively, remaining steady at 0.12% in the SR-PLGA 80/20 at 12 weeks. Compression strength of the SR-PLGA stent remained stable up to 6 weeks, after which it decreased rapidly. The new SR-PLGA 80/20 material is markedly more resistant to encrustation than metallic urethral stent materials and it retains compression strength up to 6 weeks, which is long enough for temporary stenting for most clinical indications in urology. Thus, the new stent is well suited to future clinical use.

The use of the Memokath stent in the treatment of detrusor sphincter dyssynergia in spinal cord injury patients: a single-centre seven-year experience.

A retrospective analysis of our seven-year experience with the Memokath urethral stent for the treatment of detrusor sphincter dyssynergia (DSD) in spinal cord injured (SCI) patients. Twenty five patients with SCI underwent rhabdosphincter Memokath stent insertion. The mean age was 45.5 years (range 32-65 years). The level of injury was cervical in 14 and thoracic in 11 patients. All patients were shown to have neurogenic detrusor overactivity with DSD associated with high detrusor pressures and incomplete emptying on pre-operative video-cystometrograms (VCMG). The Memokath stent was inserted using a standardized protocol. Follow-up assessment included blood chemistry, ultrasound scan (upper tracts and residual urine) at one and three months after insertion, and a follow-up VCMG at six months. The pre-operative and six-month post-operative VCMG results were analysed by the paired t-test and p value <0.05 was taken as significant. There was a significant reduction in maximum detrusor pressure, duration of contraction and residual urine volume (p<0.05) on the VCMG six months after insertion of the stent. At present six patients have a Memokath stent in situ at a mean of 34.7 months (range 6-86 months). Nineteen stents were removed for several reasons at a mean of 20.3 months (range 0.25-41 months). These include, exacerbation of autonomic dysreflexic symptoms (n=3); stent migration (n=7); encrustation and stone formation (n=5); incomplete bladder emptying without obstruction (n=3); entrance into fertility program (n=1). The Memokath stent is safe, easy and quick to insert with minimal trauma to the urethra. It is effective in the management of DSD and decreasing the detrusor pressure and residual urine volume in SCI patients. Moreover the ease of its removal in a non-traumatic fashion makes this stent an attractive option when patients are still contemplating the method of bladder management, in those wishing to be involved in fertility program and in recently SCI patients who may recover some manual dexterity to perform clean intermittent self-catheterisation. It must be remembered that this is a temporary stent, as our study clearly shows that the majority are removed within two years of insertion.

Long-term result of Memokath urethral sphincter stent in spinal cord injury patients.

BackgroundMemokath urethral sphincter stents are used to facilitate bladder emptying in patients with spinal cord injury, but long term follow-up has not been reported.MethodsCase series of ten men with spinal cord injury who underwent insertion of Memokath stents and were followed for up to nine years.ResultsWithin four years, the stent had to be removed in nine out of ten patients because of: extensive mucosal proliferation causing obstruction to the lumen of the stent; stone around the proximal end of the stent, incomplete bladder emptying, and recurrent urinary infections; migration of the stent into the bladder related to digital evacuation of bowels; large residual urine; concretions within the stent causing obstruction to flow of urine, and partial blockage of the stent causing frequent episodes of autonomic dysreflexia. In one patient the stent continued to function satisfactorily after nine years.ConclusionsThe Memokath stent has a role as a temporary measure for treatment of detrusor-sphincter dyssynergia in selected SCI patients who do not get recurrent urinary infection and do not require manual evacuation of bowels.

The self-expanding metallic ureteric stent in the long-term management of benign ureteric strictures.

To evaluate and assess the long-term complications of using the thermo-expandable, nickel-titanium alloy stent (Memokath 051, Engineers & Doctors A/S, Hornbaek, Denmark) for managing benign ureteric strictures. Over a 3-year period, 13 Memokath stents were inserted in 11 patients (mean age 58 years, range 35-85) with 12 lower ureteric strictures. The cause of the stricture was benign in all cases, i.e. radiation fibrosis in three, retroperitoneal fibrosis, ischaemic uretero-ileal anastomosis and scarring after ureteroscopy in two each, and diathermy damage, extraluminal endometriosis and stone passage in one each. Four stents were 9 F with proximal expansion to 17 F and the other nine used were 10.5 F with proximal expansion to 20 F. The patients were followed for a mean (range) of 18 (1.5-33) months. No complications or side-effects occurred with nine stents; four stents were removed at a mean (range) of 16.3 (4-33) months. Three of these had become encrusted, two of which had been placed in patients who had either a history of stone disease or recurrent urinary tract infection. The other stent had migrated. The Memokath stent appears to have a useful role in managing benign ureteric strictures, but it must be closely monitored in patients who are predisposed to encrustation.

Use of Memokath temporary urethral stent in treatment of detrusor-sphincter dyssynergia.

In spinal-injured patients, detrusor-sphincter dyssynergia (DSD) can lead to high intravesical pressures, upper tract dilation, and recurrent infections. The standard treatment for DSD is sphincterotomy and, more recently, permanent sphincter stenting. Many spinal-injury patients would prefer a reversible treatment because of concern about fertility or because they are awaiting a "miracle cure." There is also concern over the theoretical long-term risk of squamous carcinoma after permanent stenting. In view of this, the Memokath, a thermosensitive temporary stent, has been undergoing trials at our center to determine which patients could benefit. Fourteen Memokath stents have been inserted in spinal-injured patients with DSD at our center, and they have been followed up for as long as 2 years. Stents were placed under cystoscopic guidance as a day case procedure. The stents were inserted either through the sphincter alone (short [4-cm] stents; 3 patients) or through the sphincter and bladder neck (long [5-7-cm] stents; 11 patients). There were no complications during surgery in either placement or removal of these stents. There was a significant (p < 0.001) reduction in the residual urine volume after stenting. Preoperative hydronephrosis and attacks of autonomic dysreflexia noted in some patients also resolved after stenting. Short stents that bridge the external urethral sphincter were ineffective in emptying the neuropathic bladder. Therefore, we advise that only long stents that lie across both the bladder neck and the external sphincter be used. Because of its easily reversible nature, the Memokath should be adopted for use in patients who are unsure about their preferred option of bladder management and those involved in a fertility program.