A Comparison of Laser Delivery Mode & Wavelength on Varicose Veins Monika G. Kiripolsky, MD; Susan P. Detwiler, MD and Mitchel P. Goldman, MD

Purpose: To determine the effects of endovenous laser wavelengths and delivery modes (continuous diode versus pulsed Nd:YAG) on isolated veins ex-vivo both macroscopically as well as microscopically. In addition, to determine whether protected-tip fibers are effective in reducing vein wall perforations.

Methods:   An ex-vivo endovenous laser ablation model was used. Human veins harvested during ambulatory phlebectomy procedures were sutured closed at one end. Veins were then suspended by adding a weighting device, within a graduated column of warm saline at physiologic concentration. (See Figure 1).The lumen of each vein was filled with porcine blood, a fiber inserted into the lumen and the fiber attached to a mechanical pullback device (See Figure 2):

Human vein  suspended  within cylinder  of physiologic  saline (prior to  insertion of  laser fiber and  subsequent  laser  treatment) 

Vein has been  filled with porcine  blood & laser  fiber has been  inserted. Fiber is  connected to  automatic  pullback device.  The light shows  where the laser  tip is within the  vein.  

Figure 1

Figure 2

Laser and Fiber Matrix Laser:

1320nm Pulsed 1310nm CW 810nm CW 810nm CW 1470nm CW 2100nm Pulsed

No.

System Type

Power*

Pullback Rate

1 2 3 4 5 6

Nd:YAG Diode Diode Diode Diode Ho:YAG

7 watts 7 watts 7 watts 7 watts 7 watts 7 watts

1mm/sec 1mm/sec 1mm/sec 1mm/sec 1mm/sec 1mm/sec

Fiber Configuration

600um Standard Tip 600um Standard Tip 600um Protected Tip 365um Standard Tip 600um Standard Tip 600um Standard Tip

* Adjusted to 7 watts with a Molectron power meter CoolTouch Inc.

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Macroscopic Results: •

1320 nm Nd:YAG pulsed (fiber #1) with two veins treated, yielded shrinkage of the vessel with no visible perforations, no coagulum on fiber tip.

Fiber Tip

Pre - Laser

•

Post - Laser

1310 nm diode CW (fiber #2) caused vein shrinkage, but, also caused dramatic perforations.

Fiber Tip

Pre-Laser

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Post-Laser

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810 nm diode CW (fiber #3) protected tip fiber yielded vein shrinkage without perforations or coagulum formation on the tip

Fiber Tip

Pre - Laser

•

Post - Laser

810 nm diode CW (fiber#4) non-protected tip fiber yielded grossly discernable perforations and coagulum on the tip of the fiber.

Fiber Tip

Pre - Laser

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Post - Laser

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1470 nm diode CW (fiber #5) loud popping sounds; fiber appeared to stick to vein wall, dragging it along by its site of initial contact via the rate set by the pull-back device. Also, coagulum formed on the fiber tip.

Pre - Laser •

Post - Laser

2100 nm diode CW (fiber #6) loud popping sounds; fiber appeared to stick to vein wall, dragging it along by its site of initial contact via the rate set by the pull-back device. Also, coagulum formed on the fiber tip

Pre - Laser CoolTouch Inc.

Post - Laser 11_2011

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Microscopic Results: A control (untreated vein) counterpart from the same patient was analyzed histologically. Cross-sections of vessels treated with each laser fiber combination (as well as corresponding non-treated controls) were viewed and interpreted by a histopathologist who remained blind as to the laser used. Laser

No.

Total # crosssections evaluated

Thermal damage*

Perforation or full thickness necrosis of a portion of the vein wall** (# sections where finding is observed/ total # crosssections)

1320nm pulsed

1310nm diode 810nm diode protected tip 810nm diode nonprotected tip

1

13 13

PT, FT, AD 0

2/13 (15%) 0 (0%)

2

11

PT, FT, AD

7/11 (64%)

11

0

0 (0%)

11

PT

0 (0%)

7

0

0 (0%)

3

PT, FT, AD 4

11

(AD focally near

5/11 (45%)

perforations)

1470nm diode

2100nm holmium

1320nm pulsed (redo)

5

6

1

8

0

0 (0%)

6

PT, FT, AD

4/6 (67%)

14

0

0 (0%)

10

PT, FT, AD

5/10 (50%)

10

0

0 (0%)

9

PT, FT, AD

1/9 (11%)

11

0

0 (0%)

*Thermal damage (amorphous amphophilic material; coagulation necrosis) - affecting the partial thickness of media with intervening muscle cell nuclei still visible ("PT"), affecting the full thickness of media with intervening muscle cell nuclei still visible ("FT"), affecting the advential dermis ("AD") - (# sections where finding is observed/ total # cross-sections evaluated) **Perforation (channel or absence of tissue in a portion of the vein wall) or full thickness necrosis of a portion of the vein wall (muscle cell nuclei are not visible and are replaced by coagulation necrosis and amorphous basophilic material) (# sections where finding is observed/ total # cross-sections evaluated)

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1320 nm Nd:YAG pulsed (fiber #1)

•

1310 nm Diode CW (fiber #2)

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810nm Diode CW Protected Tip (fiber #3)

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810nm Diode CW Non-Protected Tip (fiber #4)

•

1470nm Diode CW (fiber #5)

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2100nm Diode CW (fiber #6)

Conclusions: •

• •

The delivery mode, pulsed Nd:YAG vs. continuous wave diode may be just as important as the wavelength when lasers are used in an endovenous ablation procedure. Thus, the 1310 nm CW laser may NOT be equivalent to the 1320 nm pulsed laser Pulsing the laser output may dislodge any coagulum from forming on the fiber tip. This could prevent high tip temperatures, which are more likely to cause wall perforations Protected tip, 810 nm fibers may be less likely to yield wall perforations than their non-protected counterparts

CoolTouch Inc.

11_2011

7075-0132 Rev A