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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

Authors Dixon C, Cedano ER, Mynderse L, Larson TR

Received 10 September 2014

Accepted for publication 9 October 2014

Published 30 January 2015 Volume 2015:7 Pages 13—18

DOI https://doi.org/10.2147/RRU.S74040

Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Editor who approved publication: Dr Jan Colli


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 hyperplasia

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