Thermosensitive stent (Memotherm) for the treatment of benign prostatic hyperplasia

Recently, more and more alternative therapeutic methods have been used for the treatment of benign prostatic hyperplasia (BPH). We will report on therapeutic results with a new thermosensitive stent system (Memotherm). This wire mesh stent has been designed especially for urological purposes. It is made of Nitinol, a thermoreactive material, and gains its maximum expansion force al body temperature. Due to the properties of the material the stent is flexible and can adapt to the anatomical conditions of the prostatic part of the urethra. Because of individual variations in the length of the prostatic part of the urethra, the system is available in lengths from 2 to 8 cm. The knitted structure for the first time allows atraumatic removal. Between April, 1992, and September, 1993, we treated a total of 54 BPH patients with the stent system. Mean patient age was 76.1 +/- 7.6 years (61-98). Mean prostatic volume was 51.9 +/- 25 ml (20-150), and the length of the applicated stents was 32.3 +/- 9.5 mm (20-70). Patient selection for stent treatment was carried out with regard to the preoperative risk status of this patient group. Fourteen (26%) of the patients treated were able to micturate before operation; in 40 (74%) urinary drainage was accomplished by means of an indwelling catheter. Following stent application, 53 out of 54 patients were able to micturate. With the first group (preoperative voiding ability), maximum flow had increased from 4.5 ml/s to a mean of 15.8 ml/s, while residual urine volume had decreased from 194.4 ml to 11.8 ml and the AUA 6 Symptoms Score had improved from 24 points to 3.5 points 6 months after stent application. All differences were statistically significant (P < 0.02). With the second group (no preoperative voiding ability), the AUA 6 Symptoms Score had improved from 25 points to 3.9 points (P < 0.02) 6 months after the operation, at which time the mean maximum flow rate was 14.8 ml/s and residual urine volume 14.8 ml. There was no statistically significant difference between the patients who were able and those who were unable to micturate before operation. One case of epididymitis was the only major complication observed after stent placement. Frequent urgency symptoms (30 out of 54 patients; 55.5%) subsided after a mean period of 1 week. The Memotherm stent offers an interesting therapeutic alternative for BPH risk patients.