Transurethral convective water vapor as a treatment for lower urinary tract symptomatology due to benign prostatic hyperplasia using the Rezūm® system: evaluation of acute ablative capabilities in the human prostate

Christopher M Dixon,1 Edwin Rijo Cedano,2 Lance A Mynderse,3 Thayne R Larson4 1Lenox Hill Hospital, New York, NY, USA; 2Department of Urology, Clinica Canela, La Romana, Dominican Republic; 3Department of Urology, Mayo Clinic, Rochester, MN, USA; 4Institute of Medical Research, Scottsdale, AZ, USA Background: The purpose of this study was to assess the acute ablative characteristics of transurethral convective water vapor (steam) using the Rezūm® system in men with benign prostatic hyperplasia through histologic and radiographic studies. Methods: Seven patients were treated with transurethral intraprostatic injections of sterile steam under endoscopic visualization followed by previously scheduled adenectomies. The extirpated adenomas were grossly examined followed by whole mount sectioning and staining with triphenyl-tetrazolium chloride (TTC) to evaluate thermal ablation. Histology was performed after hematoxylin and eosin staining on one prostate. After review of results from the first patient cohort, an additional 15 patients with clinical benign prostatic hyperplasia were treated followed by gadolinium-enhanced magnetic resonance imaging (MRI) at one week. Results: In the first patient cohort, gross examination of TTC-stained tissue showed thermal ablation in the transition zone. In addition, there was a distinct interface between viable and necrotic prostatic parenchyma. Histopathologic examination revealed TTC staining-outlined necrotic versus viable tissue. Gadolinium-enhanced MRIs in the cohort of 15 patients demonstrated lesion defects in all patients at 1 week post-procedure. Coalesced lesions were noted with a mean (± standard deviation) lesion volume of 9.6±8.5 cm3. The largest lesion volume was 35.1 cm3. Ablation using vapor was rapid and remained confined to the transition zone, consistent with the thermodynamic principles of convective thermal energy transfer. Conclusion: Thermal ablation was observed in all specimens. The resulting coalescing ablative lesions, as seen on MRI, were confined to the transition zone. These studies confirm the ablative capabilities of vapor, validate the thermodynamic principles of convective heating, and allow for further clinical studies. Keywords: steam, vapor therapy, thermotherapy, minimally invasive, lower urinary tract symptomatology, benign prostatic hyperplasi

Two-year results after convective radiofrequency water vapor thermal therapy of symptomatic benign prostatic hyperplasia

Christopher M Dixon,1 Edwin Rijo Cedano,2 Dalibor Pacik,3 Vítězslav Vit,3 Gabriel Varga,3 Lennart Wagrell,4 Thayne R Larson,5 Lance A Mynderse6 1Department of Urology, Phelps Memorial Hospital, Sleepy Hollow, New York, NY, USA; 2Department of Urology, Clinical Canela, La Romana, Dominican Republic; 3Department of Urology, Brno University Hospital, Brno, Czech Republic; 4Urologcentrum, Stockholm, Sweden; 5Institute of Medical Research, Scottsdale, AZ, 6Department of Urology, Mayo Clinic, Rochester, MN, USA Objective: The objective of this study was to assess the effectiveness and safety of convective radiofrequency (RF) water vapor thermal therapy in men with lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH); a pilot study design with 2-year follow-up evaluations.Patients and methods: Men aged ≥45 years with an International Prostate Symptom Score ≥13, a maximum urinary flow rate (Qmax) ≤15 mL/s, and prostate volume 20–120 cc were enrolled in a prospective, open-label pilot study using convective RF water vapor energy with the Rezūm System. Patients were followed up for 2 years after transurethral thermal treatment at 3 international centers in the Dominican Republic, Czech Republic, and Sweden. The transurethral thermal therapy utilizes radiofrequency to generate wet thermal energy in the form of water vapor injected through a rigid endoscope into the lateral lobes and median lobe as needed. Urinary symptom relief, urinary flow, quality of life (QOL) impact, sexual function, and adverse events (AEs) were assessed at 1 week, 1, 3, 6, 12, and 24 months. Results: LUTS, flow rate, and QOL showed significant improvements from baseline; prostate volumes were appreciably reduced. Sexual function was maintained and no de novo erectile dysfunction occurred. The responses evident as early as 1 month after treatment remained consistent and durable over the 24 months of study. Early AEs were typically transient and mild to moderate; most were related to endoscopic instrumentation. No procedure related to late AEs were seen. Conclusion: The Rezūm System convective RF thermal therapy is a minimally invasive treatment for BPH/LUTS which can be performed in the office or as an outpatient procedure with minimal associated perioperative AEs. It has no discernable effect on sexual function and provides significant improvement of LUTS that remain durable at 2 years. Keywords: benign prostatic hyperplasia, lower urinary tract symptoms, convective RF, water vapor thermal therapy, minimally invasive&nbsp