Category: Basic Science: BPH/LUTS

MP3-5 - A comparison of the tissue effects of 120-W Ho:YAG, Continuous Wave and Super Pulse Tm-fibre Lasers

Thu, Sep 20
4:00 PM - 6:00 PM

Introduction & Objective : Ho:YAG, Tm:YAG and Tm-fibre lasers (TFL) are used for the treatment of benign prostatic hyperplasia. Laser radiation is emitted in Ho:YAG lasers in a super pulse (SP) mode, in Tm:YAG lasers in a continuous wave (cw) mode, whereas the novel SP TFL can emit laser radiation in a SP or cw mode. Aim of this study was to measure the characteristics of tissue vaporization, incision, and coagulation using a Ho:YAG laser, a SP TFL and a cw TFL.

Methods : A Ho:YAG laser, SP TFL, and a cw TFL with an average power of 120-W were compared. Energy was delivered using a 600 µm bare-ended laser fibre and tested in soft tissue samples from fresh non-frozen porcine kidneys. A motorized translation XY stage for controlling the cutting speed (2 and 5 mm/s) was used. The gap between the fibre and tissue was kept at a constant distance of 0.5±0.1mm. Lactat Dehydrogenase (LDH)-staining of the specimens was performed for histological evaluation. Incision depth, zones of vaporization, coagulation, and thermo-mechanical damage, defined as superficial layer of laser wound with pronounced irregular mechanical damage of coagulated tissue was measured. Data were expressed as mean±SD.

Results : Characteristics of the lasers, laser settings, and the results of histological evaluation are shown in Table 1. Incision depth of cw TFL was 3-4 times larger than that of Ho:YAG laser. Vaporization volume was highest for cw TFL and was 2.5-4.5 higher than for Ho:YAG laser. SP TFL at equal energy setting with Ho:YAG laser (2 J) demonstrated equal vaporization volume at 2 mm/s cutting speed and 2 times higher vaporization volume at 5 mm/s. Coagulation zones of Ho:YAG laser and SP TFL with equal energy per pulse at 2 J were equal and about 3 times smaller than that of cw TFL. Carbonization was not observed for Ho:YAG and SP TFL and was most pronounced for cw TFL at lower speed of cutting (2 mm/s). Thermal mechanical damage zones were similar for Ho:YAG and SP TFL at equal energy settings. Thermal mechanical damage was not observed for cw TFL.

Conclusions : SP TFL effects on tissue can be controlled in wide range by adjusting laser parameters from very high and deep vaporization and coagulation to more superficial thermo-mechanical damage which is more typical of Ho:YAG laser. 

Christopher Netsch

Asklepios Klinik Barmbek, Abteilung für Urologie
Hamburg, Hamburg, Germany

Dr. med. Dr. habil. Christopher Netsch, MD, FEBU is an Assistant Professor of Urology at the Semmelweis University of Budapest/Hungary. He received his medical degree from the University of Mainz/Germany. His training in urology was conducted at the Inselspital Bern/Switzerland, Städtisches Klinikum Karlsruhe/Germany and at the Asklepios Klinik Barmbek/Germany. After his board certification in 2011 (Hamburg/Germany), Dr. Netsch became a consultant urologist at the Asklepios Klinik Barmbek/Germany. Dr. Netsch completed his Endourology Fellowship at the Asklepios Klinik Barmbek in 2012. He was also qualified as a Fellow of the European Board of Urology (FEBU) in 2015.
Dr. Netsch`s research focuses on urolithiasis and minimally-invasive therapies for BPH. He has authored or co-authored over 70 peer-reviewed journal articles and numerous book chapters. He was awarded with the Mauermayer award of the German Society of Urology (DGU) in 2013 and the Hans Marberger award of the European Association of Urology (EAU) in 2014. He is currently an editorial consultant for the World Journal of Urology.
Dr. Netsch is a member of the DGU Urolithiasis Guidelines committee. He is also an active member of numerous national and international societies such as the DGU, EAU, and the Endourological Society. He is also a member of the DGU working group in Endourology and the EAU section of Uro-Technology (ESUT): Lower Tract Section.

Dmitry Enikeev

Deputy Director for Science
Institute for Urology and Reproductive health, Sechenov University
Moscow, Moskva, Russia

Surgical experience:
Experienced in TURP (>300 surgeries).
Experienced in upper urinary tract endosurgery (PCNL >200, RIRS >200).

2008-Present: Multiple upper and lower urinary tract surgeries;
2011-Present: HoLEP (400 surgeries);
2011-Present: En-bloc enucleation of bladder tumor (50 surgeries);
2016-Present: ThuLEP (>400 surgeries);
2016-Present: Thulium en-bloc enucleation of bladder tumor (>80 surgeries);
2016-Present: Brachytherapy (>40 surgeries); prostate cryoablation (70 surgeries), renal cancer cryoablation (30 surgeries);
Apr 2017-Present: Irreversible electroporation (10 surgeries);
Apr 2017-Present: MR-fusion prostate biopsy (80 procedures).

Petr Glybochko

RI for Uronephrology, Sechenov University
Moscow, Moskva, Russia

Mark Taratkin

Institute for Urology, Sechenov University
Moscow, Moskva, Russia

Researcher at the Institute for Urology and Reproductive health, Sechenov University.
Head of the laser technology lab.

Benedikt Becker

Asklepios Klinik Barmbek, Department of Urology
Hamburg, Hamburg, Germany

Dr. Becker is a resident of urology in the urological department of the Asklepios Hospital Barmbek in Hamburg, Germany. He studied in Giessen and Lübeck (both Germany). His main scientific interest is the broad spectrum of endourology, especially laser treatment of benign prostatic obstruction. He is an active member of the German Society of Urology (DGU), the German Society of Residents in Urology (GeSRU), and the Endourological Society (WCE). At this time, he is participating in the Two Year fellowship program in Endourology/Stone Surgery.

Andreas J. Gross

Head of Department
Asklepios Klinik Barmbek, Abteilung für Urologie
Hamburg, Hamburg, Germany