1. SITE 2013 Barcelona, May 8th to 11th, 2013
Laser Fluence Affects Recanalization after Endovenous Laser Therapy for Saphenous Varicose Veins
1. Tokyo Vein Clinic
2. Tokyo Metropolitan Geriatric Hospital,
Department of Vascular Surgery
Go Urabe1,2, Keisuke Kondoh1, Tatsu Nakazawa2
Today, I’ll talk about recanalization of endovenous laser therapy for saphenous varicose veins.
TOKYO VEIN CLINIC

2. Background and study purpose
Recently, the number of Endovenous Laser Therapy (EVLT) for Saphenous Varicos Veins is increasing instead of conventional stripping.
Recanalization after EVLT is rare, but it often needs additional treatments.
The risk factor of recanalization remains uncertain.
This study aims to investigate its risk factors.
Let me first talk about the background of this study.
In Japan, endovenous laser therapy on saphenous varicose vein has been covered by health insurance, since January 2011.
So, number of EVLT is increasing.

3. Study design
We defined recanalization as patency of ablated saphenous vein more than five centimeter from the saphenous junction
Risk factors for recanalization were compared with occluded veins and recanalized veins by univariate and multivariate analyses
Retrospective study
In this study, we defined recanalization as total longitudinal patency of ablated saphenous vein, because partial patency is not clinically important.
Risk factors for recanalization were compared with occluded and recanalized veins by univariate and multivariate analyses.
And this is a retrospective study with medical record.

4. Risk factors Age Sex Saphenous vein (GSV or SSV)
Medication of anticoagulant drugs
Maximum diameter of the proximal vein (mm)
LEED: linear endovenous energy density (J/cm)
Laser fluence (J/cm2)
These are list of risk factors analysed in this study.
Let me talk about the last two factors of laser energy.

5. Indices of laser energy
LEED: Linear Endovenous Energy Density
{Laser energy (J)} / {Length (cm)}
Laser fluence:
{LEED (J/cm)} / {Max. diameter of proximal vein (cm)}
LEED (J/cm)
LEED is a linear endovenous energy density: J/cm.
On the other hand, laser fluence is an energy density of vascular surface area: J/cm2.
In this study, we defined laser fluence as LEED divided by maximum diameter of proximal saphenous vein (cm)
Fluence (J/cm2)

6. Patients From January 2011 to June 2012,
850 saphenous varicose veins in 648 patients were performed EVLT with ELVeSTM laser (wave length: 980nm) at Tokyo Vein Clinic

7. Procedure of EVLT
Patients were put under sedation with intravenous injection of midazolam and propofol
Saphenous vein was accessed by puncturing
with duplex guidance
Tumescent local anesthesia was infiltrated in the saphenous compartment with duplex guidance
From the position of 1-2 cm distal to the SFJ, laser fiber was withdrawn with continuous laser energy of 8-10W
We don’t perform stab phlebectomy

8. Post operative follow up
Duplex scan was performed at one week,
1, 3, 6, and 12 months after the operation
We recommend patients to wear elastic stockings for three months after the operation
At the early period from January to February 2011, we didn’t care about laser ablation power. But, from March 2011, we controlled it as J/cm.
Post operative follow up with duplex scan was performed at 1 week and at 1,3,6, and 12 months after the operation.
Patients wore elastic stockings for three months after the operation.

9. Background of patients
Age
60.2±11.2 y.o.（13-88 y.o.）
Sex　
female 　643 limbs in 483 patients male limbs in 165 patients
Vein
great saphenous vein limbs
small saphenous vein limbs
Medication
33/648 patients (5.1%)
Max. diameter of vein (mm)
12.0±3.7 ( )
LEED (J/cm)
71.7±11.6 ( )
Laser fluence (J/cm2)
66.3±26.1 ( )
This table shows patient’s background.

10. List of recanalized veins 12/850 veins (1.4%)
Age
Sex
Vein
Medication
Max diam.
(mm)
LEED
(J/cm)
Fluence
(J/cm2)
Duration
Partial / Total
Recanalization
Reoperation 48 M
GSV -
13.1
46.2
35.3 3M T 71 F
13.7
41.5
30.3 1W + 40
13.0
47.4
36.5 39
11.4
82.8
72.6 58
SSV
16.3
82.3
50.5 1M
13.4
65.3
48.7 P 65
15.8
76.5
48.4
9.7
79.7
82.2 44
19.1
78.7
41.2 60
14.5
85.3
58.8
19.9
74.6
37.5 75
81.9
63.0
Recanalization occurred in 12 limbs of 12 patients.
This table shows most of our recanalization occurred within a month after the operation.
We performed re-operation for veins of total recanalization.

11. Univariate analyses of risk factors
occluded
n=838
recanalized
n=12
p value
Age
60.2±11.1
58.0±12.5
0.49*
Sex (female)
632/838 (75.4%)
11/12 (91.7%)
0.19#
Vein (GSV)
676/838 (80.7%)
0.34#
Medication
41/838 (4.9%)
2/12 (17%)
0.065#
Max diameter (mm)
11.96±3.68
14.41±2.96
0.022*
LEED (J/cm)
71.8±11.5
70.2±16.1
0.64*
Laser fluence (J/cm2)
66.5±26.1
50.4±16.0
0.033*
Among these, p value of 0.2 or less were taken into multivariate analysis.
#　Pearson’s χ2 test , *　Student’s t test

12. Multivariate analysis of risk factors
Logistic regression analysis
(Stepwise method)
Risk factor
p value X2
Max. dimeter
0.817
0.054
Medication
0.062
3.50
Laser fluence
0.021
5.35
Multivariate analysis showed laser fluence was the only significant risk factor.

13. Box plot of laser fluence
(J/cm2)
Laser fluence
Recanalized
Occluded

14. Receiver operating characteristic (ROC) curve of laser fluence and recanalization
63.0
Sensitivity
50.5
Values at the dots
are laser fluence
(J/cm²)
41.2
1 - (Specificity)

15. Conclusion Our recanalization rate was 1.4%
Most of our recanalization occurred within a month from the operation
Laser fluence was the only significant risk factor of recanalization
Laser energy should be controlled by the diameter of the vein

16. Study limitations Laser fluence was defined as LEED (J/cm)
/ {max. diameter of the proximal vein (cm)}
precise location of venous max. diameter
was not taken into consideration
Velocity of laser fiber withdrawal was not constant
LEED and laser fluence were not constant through
the saphenous vein