A variety of techniques have been introduced over the last 15 years using heat to destroy prostate tissue to relieve obstruction and other symptoms of BPH. The latest of these is transurethral WIT (ArgoMed Inc., Cary NC). This technique was conceived, designed, and a com pany (ArgoMed) was formed to produce the catheter. After initial testing, the WIT treatment was investigated in a multiinstitutional Food and Drug Administration-approved study reported by Muschter and associates (5).
The mechanism of action of WIT is coagulation necrosis, which does not occur below 45 °C. The correlation of time and temperature is not fully known and may vary; however, it may take up to an hour at 45.5°C and only minutes at 60°C. Between 60° and 100°C, coagulation is nearly instantaneous. Temperatures over 100°C may vaporize tissue (6).
WIT is performed using the Thermoflex (ArgoMed Inc, Cary NC) system. The system consists of a console that heats and pumps the water into a treatment balloon inflated to 50 Fr within the prostatic fossa, which receives 60°C water for 45 min. There is also a balloon inflated with 16 mL of air located in the bladder. The catheter is insulated except for the balloon in the prostatic urethra. Treatment balloons are available in lengths of 20-60 mm in 5-mm increments, allowing balloon length to be matched to prostate length. The treatment is not effective for median lobe prostatic hypertrophy.
Topical urethral anesthesia is given with 2% lidocaine gel. We have not found it necessary to use other analgesia. The treatment 18 Fr catheter is passed; if there is a problem, the catheter can be passed over a wire placed in the bladder with a flexible cystoscope. All patients are discharged home the day of treatment with a Foley catheter to manage prostatic swelling. Half of the patients need the catheter for only a week. An additional 30% are catheter-free at 2 wk, but some patients require a catheter for 3-5 wk.
The depth of necrosis from WIT therapy was around 10 mm in prostate specimens studied by Corica and co-workers (7). In the European multiinstitutional study, at 2 yr, peak flow was increased by 96%, International Prostate Symptom Score (I-PSS) decreased 52%, and quality of life scales decreased by 41% (5).
We have treated 40 patients at our institution. Of these, 25 had chronic urinary retention with catheter drainage or had residual urine levels >600 mL. All of these patients were in poor health and averaged 79.6 yr of age; many were in nursing homes. Treatment was done on an outpatient basis without sedation or analgesics. One patient had a thalamic stroke 1 mo later and was not given a voiding trial because he could not stand or ambulate. One passed his voiding trial but died of bladder cancer 13 mo later. Voiding trials have failed in five; one is on intermittent catheterization; four had a subsequent TURP. In two, the pathology report revealed prostatic cancer. Two had a median lobe that was not recognized on flexible cystoscopy. Interestingly, one had a concave hollowing out of the middle lobe from the heat therapy. On cystogram, only one patient had a hollowed-out prostatic fossa. In the 19 patients who can void, the postvoid residual volume (PVR) averaged 38.7 mL, time-to-removal of the catheter was 4.8 wk, flow rates were 6-10 mL/s, and urodynamic studies showed mild obstruction of 2-4/6 (1 is normal and 6 is obstructed).
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