Holmium YAG Laser: Is it the end of the Era for Stone Management

• 15 Jan 2020 10:47:06 AM
• |Endo Urology

Dear All,

The flash lamp-pumped, solid-state Holmium YAG Laser has been the Laser of choice for use in ureteroscopic lithotripsy for the past 20 years. However, although the holmium laser works well on all stone compositions and is cost-effective, this technology still has several fundamental limitations. The use of a ‘dusting’ mode with low pulse energy (0.2–0.4?J) and high pulse rate (50–80?Hz) settings, is gaining popularity in lithotripsy due to the desire to produce smaller residual stone fragments during ablation, capable of being spontaneously passed through the urinary tract. Recent developments in the Holmium YAG Laser lithotripsy include the introduction of pulse modulation. This technique delivers the laser energy in an asymmetric manner such that an initial bubble is created (the ‘Moses effect’) through which the remainder of the energy can then travel through without being absorbed by surrounding water.

Each of these laser technologies is associated with technical advantages and disadvantages, and the search continues for the next generation of laser lithotripsy systems that can provide rapid, safe, and efficient stone ablation. New fibre-optic approaches for safer and more efficient delivery of the laser energy inside the urinary tract include the use of smaller-core fibres and fibres that are tapered, spherical, detachable or hollow steel, or have muzzle brake distal fibre-optic tips. These specialty fibres might provide advantages, including improved flexibility for maximal ureteroscope deflection, reduced cross section for increased saline irrigation rates through the working channel of the ureteroscope, reduced stone retropulsion for improved stone ablation efficiency, and reduced fibre degradation and burn back for longer fibre life.

The frequency-doubled, double-pulse YAG (FREDDY) Laser has been tested as a more compact and efficient solid-state laser than the initial dye lasers for short-pulse lithotripsy, but the FREDDY laser is not effective for all stone compositions. The Erbium: YAG Laser has been tested for efficient ablation of urinary stones, but a suitable mid-infrared optical fibre delivery system is not available for this procedure.

The Thulium fibre laser (TFL) is the most promising alternative to holmium for lithotripsy owing to its use of a more suitable TFL wavelength, smaller fibres, and potential for using a smaller, less expensive laser system; however, clinical studies are needed to assess this new technology. TFL promotes the development of novel miniature fibre-optic delivery systems, including tapered, ball tip, hollow steel tip fibres, and muzzle brake fibre-optic tips, which can reduce both fibre burn back or degradation and stone retropulsion without sacrificing laser ablation rates.

Luke A Hardy, Nathaniel M Fried et al (2019) compared Thulium vs Holmium YAG at three settings and found Holmium laser ablation rates were lower than for TFL. For all three settings combined, 7% stones treated with Holmium Laser were completely fragmented in ?5 minutes compared to 60% stones treated with TFL.

Miniaturization holds the key. With the introduction of both new modifications of time-tested technologies as well as completely novel modalities, the practicing urologist's armamentarium of devices for the surgical management of kidney stones continues to grow. As the popularity of ‘mini’ procedures continues to grow, the adaptability of these technologies to these procedures will be critical to maintain maximum relevance.

I am providing two articles addressing the utility of TFL over Holmium. There are overlaps in the articles provided but collectively they address why Thulium could replace Holmium in near future.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6790412/pdf/tau-08-S4-S398.pdf

https://link.springer.com/content/pdf/10.1007/s00345-019-02654-5.pdf

Are we likely to see the end of our old friend Holmium YAG from the management of Stones in the near future?

Venu

Comments(4)

• 

  Tanuj Paul Bhatia

  18 Jan 2020 06:08:27 AM

  Sir I feel it will take 5 more years to answer if TFL will replace Ho:YAG. Even in thullium fiber there are upgrades coming up. While The one being launches by Olympus will be slightly different , quanta is coming up with some major changes in TFL and pushing for FDA and CE approvals. Even Lumenis might come up with TFL technology soon. So there will be competition which is always good for the customer.

• 

  Abhay Mahajan

  19 Feb 2020 09:22:26 PM

  I am using Thulium fibre laser for stones at present since few months.My observations-

  Upside-

  1. Excellent stone dusting as well as fragmentation. In fragmentation mode, the stone particle size is very small compared to Holmium laser

  2. Faster ablation rate

  3. Special advantage during RIRS as less frequent use of accessory instruments & repeat procedures

  4. In Miniperc procedure the stone fragments are much smaller,which results in rapid clearance. 

  Downside-

  1. Slightly Prolonged hematuria. Usually not alarming. Subsides.

  2. During rigid URS can cause mucosal blanching. Keep low power settings.

  3. Machine marketed by Olympus is USFDA approved now.

   

• 

  Dr. Anil Takvani

  20 Feb 2020 10:27:07 AM

   "During rigid URS can cause mucosal blanching. Keep low power settings.

   Slightly Prolonged hematuria. Usually not alarming. Subsides."
  

  Downsides written by Dr. Abhay Mahajan.

  I think these is because of high velocity dusting or breaking of stones.

  Stones strikes to wall with high intensity causing not only haematuria but micro injuries to mucosal wall specifically in upper ureter impacted stones. This can lead to inflammatory granulation( stone granuloma) formation with stone dusts within, can lead to stricture formation in ureter. 

  This is even possible with holmium laser. I refrain prolong dusting in upper ureter in impacted stone in situ. Rather prefer breaking in to fragments, pushing into pelvis with saline flow at earliest and dusting into more spacious place.

  I would like to know from Abhay and other experts of URS/RIRS on ureteric mucosa injuries while prolonged lasing and stricture formation.

  Thanks 

  
  

• 

  Abhay Mahajan

  20 Feb 2020 04:23:13 PM

  Anil, I perfectly agree with you. I have seen two ureteric strictures post URS with Holmium Laser lithotripsy. So its not that the Thulium Fiber laser has to be blamed.