- Journal of Vascular Surgery: Venous and Lymphatic

Experimental determination of the best time and
duration for endovenous great saphenous vein
electrocoagulation
Fabio Henrique Rossi, MD, PhD, Camila Baumann Beteli, MD, Mabel Barros Zamorano, MD,
Patrick Bastos Metzger, MD, Cybelle Bossolani Onofre Rossi, FACS, Nilo Mitsuru Izukawa, MD, PhD, and
Amanda Guerra de Moraes Rego Sousa, MD, PhD, São Paulo, Brazil
Objective: Endovenous electrocoagulation provokes immediate
selective venous wall necrosis. In this study, we aim to determine the best power and time of electrocoagulation necessary
to cause intima and media but not adventitia layer damage
in great saphenous vein (GSV) insufficiency treatment.
Methods: We studied 100 varicose GSV fragments submitted to
endovenous electrocoagulation. The power (60, 90, or 120 W)
and time (5, 10, or 15 seconds) were randomly assigned. The
fragments were submitted to histopathologic examination to
analyze the depth of tissue necrosis. Dose-response models for
the analysis of binary data were used to identify the best association between power and the time of electrocoagulation
necessary to cause intima and media but not adventitia layer
necrosis. We also applied a logistic regression model to investigate the impact of body mass index and GSV diameter
on the electrocoagulation effects.
Results: The time (odds ratio [OR], 1.26; P [ .0009) was
found to be a stronger predictor of the depth of vessel necrosis
than the power of electrocoagulation applied (OR, 1.05; P <
.0001). The power and time that were most likely to cause intima and media but not adventitia layer destruction were
60.4 W 3 5 seconds, 58.8 W 3 10 seconds, and 8.9 W 3 15
seconds. The initial GSV diameter (median, 5.36 mm; minimum, 2.3 mm; maximum, 10 mm; OR, 0.96; P [ .82) and
body index mass (median, 24.7 kg/m2; minimum, 15.6 kg/m2;
maximum, 36.2 kg/m2; OR, 1.08; P [ .26) showed a poor
correlation with the depth of histologic vessel destruction.
Conclusions: The time of electrocoagulation strongly predicts
the depth of GSV wall necrosis more than the amount of
power applied. Determination of the best time and power of
electrocoagulation ratio may help optimize GSV endovenous
electrocoagulation closure rates and decrease the complications index. The GSV diameter and body mass index do not
influence endovenous electrocoagulation effects. (J Vasc Surg:
Venous and Lym Dis 2014;2:315-9.)
Chronic venous insufficiency affects 20% of the adult
population, with varicosities in the great saphenous vein
(GSV) distribution being the most common manifestation.
The standard treatment has historically been high GSV
ligation and stripping. In recent years, many surgeons
have adopted endovascular techniques with good results.1,2
In our prior publications, we have described an endovenous electrocoagulation apparatus and technique that provoke immediate selective venous wall damage in an animal
model.3 Furthermore, we demonstrated the same effect in
human varicose veins, including the fact that the time of
electrocoagulation strongly predicts the depth of vessel
wall necrosis more than the power of energy applied.4
In this study, we aim to determine the best power and
the time of electrocoagulation necessary to cause intima
and media but not adventitia layer damage in lower limb
varicose vein treatment.
From the Dante Pazzanese Cardiovascular Institute.
This article received a research grant from FAPESP.
Author conflict of interest: none.
Reprint requests: Fabio Henrique Rossi, MD, PhD, Av Dr Dante Pazzanese, 500, Ibirapuera, São Paulo, SP, CEP 04012-909, Brazil (e-mail:
[email protected]).
The editors and reviewers of this article have no relevant financial relationships to disclose per the Journal policy that requires reviewers to decline
review of any manuscript for which they may have a conflict of interest.
2213-333X/$36.00
Copyright Ó 2014 by the Society for Vascular Surgery.
http://dx.doi.org/10.1016/j.jvsv.2013.11.001
Clinical Relevance: The successful treatment of lower extremity
chronic venous insufficiency includes the elimination of all
sources of venous reflux. Endovenous ablation of varicose veins
with radiofrequency ablation and endovenous laser therapy has
reported advantages over traditional open surgical treatment
but is costly. We have described a simple endovenous electrocoagulation apparatus and technique that provoke immediate
selective venous wall damage and use a conventional electrosurgical generator as the energy source. In this study, we aim
to determine the best power and the time of electrocoagulation
necessary to cause intima and media but not adventitia layer
damage in lower limb varicose vein treatment.
METHODS
The study was conducted according to the Helsinki
Declaration. The experimental protocol and informed consent were approved by the Institutional Review Board. All
the study subjects gave informed consent with local ethical
committee approval (IDPC-FMUSP/CEP 3904/2010).
We studied 100 varicose vein fragments obtained from
78 patients with clinical, etiologic, anatomic, and pathologic
classes 3 to 6; GSV insufficiency with venous diameters between 2.3 and 10 mm (mean, 5.36 mm) was documented
by ultrasound examination. Subjects with GSV diameter
>12 mm and <2 mm, acute or previous phlebitis, previous
surgery or sclerotherapy in the study leg, previous or current
315
316 Rossi et al
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS
July 2014
For safety reasons, we checked the best association between power (watts) and the time (seconds) of electrocoagulation necessary to cause intima and media (group A) but
not adventitia layer necrosis (group B). Dose-response
models for the analysis of binary data were used for this
investigation and tolerated the presence of vessel perforation in 10% of the cases.
A logistic regression model was applied to investigate
the impact of body mass index, saphenous vein initial diameter, and temperature on the depth of vessel wall necrosis
caused by the electrocoagulation. The test was considered
statistically significant when P < .05.
RESULTS
Fig 1. Endovenous electrocoagulation apparatus positioned at the
proximal portion of the great saphenous vein (GSV).
deep venous thrombosis, previous coagulopathy history
(congenital or acquired thrombophilia or a prothrombotic
state), arterial occlusive disease, active malignant disease,
pregnancy, multiple saphenous aneurysms (segmental varicose vein dilatations, two times the adjacent GSV diameters),
or congenital malformations were excluded.
Patients were submitted to standard surgical groin and
ankle GSV dissection. Just before high ligation and stripping
of the GSV, an endovenous electrocoagulation apparatus
was positioned immediately beneath the superficial epigastric
vein (Fig 1). The diameter of this segment was measured in
millimeters and submitted to endovenous electrocoagulation
with use of the Valleylab FX Electrosurgical Generator
(Covidien, Mansfield, Mass) as the energy source. The energy
intensity, power, and time of electrocoagulation were determined according to a randomization table. In a previous
study, we observed that electrocoagulation with 120 W for
15 seconds could provoke macroscopic GSV shrinkage, induration, and inside carbonization. We fixed this as the highest
dose and randomly studied the histologic effects of 60, 90,
and 120 W per 5, 10, and 15 seconds4 (Table I). Immediately
after the procedure, the temperature adjacent to the vessel was
measured (TD-100 thermometer; ICEL, Manaus, Brazil).
The venous fragments submitted to electrocoagulation
(20 mm) were extracted and fixed by 75% alcohol; the paraffin
inclusions were stained with hematoxylin and eosin, crosssectioned, and submitted to light microscopy. Presence of
vacuolization, delamination, coagulation, loss of tissue, perforation, nuclear rarefaction and pyknosis with disappearance of
the cellular membrane, and cytoplasm fusion due to the coagulation process were investigated and considered signs of electrocoagulation effects.5,6 The damage of the venous wall was
then classified according to the depth of appearance of these
effects: group A, intima and media necrosis; and group B,
intima, media, and adventitia necrosis. In the postoperative
period, occurrence of deep venous thrombosis was investigated by duplex scanning done immediately before the
patient’s hospital discharge and 30 days after the procedure.
The histologic evaluation of the studied fragments
showed damage to the intima in all specimens, fullthickness vessel injury in 53 specimens (53%), and perforation in 1 (1%) (Table II). Samplings of the vessel wall
circumference damages caused by the electrocoagulation
are shown in Fig 2. The temperature reached at the tissue
adjacent to the electrocoagulation (median, 51.6 C; minimum, 32 C; maximum, 82.2 C; P ¼ .0006) and the depth
of vessel destruction (P < .0005) were correlated to the energy of electrocoagulation applied.
The initial GSV diameter (median, 5.36 mm; minimum,
2.3 mm; maximum, 10 mm; odds ratio [OR], 0.96; P ¼ .82)
and body index mass (median, 24.7 kg/m2; minimum,
15.6 kg/m2; maximum, 36.2 kg/m2; OR, 1.08; P ¼.26)
showed a poor correlation with the depth of histologic vessel
destruction. The time of electrocoagulation (OR, 1.26;
P ¼ .0009) was found to be a stronger predictor of this
phenomenon than the power used (OR, 1.05; P < .0001)
(Table III).
We fixed the electrocoagulation time and measured
what would be the power that minimizes the chances of
adventitia layer necrosis and considered that this fact would
be tolerable in 10% of the cases. We found that the best
power time ratio would be 60.4 W 5 seconds,
58.8 W 10 seconds, and 8.9 W 15 seconds (Fig 3).
DISCUSSION
Laser and radiofrequency energy causes thermal ablation of the inner layers of the vessel and promotes their
Table I. Endovenous electrocoagulation randomization
table
Group
I
II
III
IV
V
VI
VII
VIII
IX
X
Energy (J)
Power (W)
0
300
600
900
450
900
1350
600
1200
1800
0
60
60
60
90
90
90
120
120
120
Time, seconds
15
5
10
15
5
10
15
5
10
15
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS
Volume 2, Number 3
Table II. Presence of thermal damage found in the
intraluminal surface of 100 great saphenous vein (GSV)
fragments subjected to endovenous electrocoagulation
and examined by light microscopy
Circumference
No.
%
Statistical
analysis
Intima and media (group A)
Intima, media, and adventitia
(group B)
Perforation
100
53
100
53
c2
1
1
P ¼ .0003
occlusion.5,7 Although good clinical results have been
shown, the complete mechanism of action of these procedures is still poorly understood.8,9 Few histologic studies
have been done of GSV alterations produced by thermal
damage.5 In an animal model, we showed that conventional electric energy could selectively cause the destruction
of the inner layers of veins.3 Previous studies have demonstrated the applications of electrocoagulation, but inconclusive results and the lack of familiarity with
catheterization techniques by the vascular surgeons of the
past discouraged its clinical application.10-16
Thermal ablation treatment success depends on high
temperatures, but this factor may lead to the injury of
structures that are adjacent to the vessel treated. Complications such as pain, skin burns, nerve damage, and deep
venous thrombosis may occur. A number of recent studies
have tried to reduce these complications by changing the
methods of application of the radiofrequency ablation
and laser energy,8,9 and others have tried new methods
of GSV occlusion with steam17 and glue.18
The heat changes produced by laser energy and radiofrequency ablation on the venous wall are apparently dependent on fluency (F), which represents the result of power
expressed in watts multiplied by time (T) of exposure
Rossi et al 317
divided by irradiated surface (S) ratio (F ¼ W T/S).
This also seems to be true for GSV electrocoagulation, as
could be shown in our previous publications. During these
experiments, we also found that these parameters were
higher than those necessary in laser and radiofrequency
thermal ablation.3,4
In bipolar radiofrequency ablation, the energy heats
the catheter and is transmitted to the vessel wall by convection (so the tumescence anesthesia is necessary).19 In electrocoagulation, the heat is created at the contact points
between the wire and the vessel wall. In conventional
monopolar electrosurgery, the active electrode is located
in the surgical site; in our method, it is inside the vessel.
The patient return electrode is somewhere else on the patient’s body. The current passes through the patient’s body
as it completes the circuit from the active electrode to the
patient return electrode. Therefore, some energy may be
lost during this process. For these reasons, we specifically
studied the GSV diameter and the patient’s body mass index and found that these variables did not interfere with
the depth of electrocoagulation vessel destruction.
The average temperatures observed during endovenous electrocoagulation in this study were lower than those
achieved during laser and radiofrequency treatment.20 This
suggests that mechanisms other than thermal ablation may
be involved. Some authors have found that electric burns
cause tissue destruction by thermoelectric and also by electromechanical effectsdthe breakdown of cell membranes
by electric and mechanical stress.21 We still do not know
if this phenomenon happens during endovenous electrocoagulation, but this could be an advantage, as we know
that high temperatures may be also responsible for adjacent
tissue complications.
Tumescence anesthesia is essential in laser and radiofrequency endovenous ablation. The pressure of the fluid
reduces the diameter of the vein, thus optimizing the
contact of the fiber with the vein wall. Endovascular
Fig 2. Cross-section of great saphenous vein (GSV) proximal fragment taken immediately after endovenous electrocoagulation. Group A: Necrosis (*), loss of substance of the intima (I), and vacuolization of the internal elastic
and internal layers of the media (M) are visible. The adventitia layer (A) is intact (hematoxylin and eosin stain, 25).
Group B: Vessel full-thickness thermal damage is evident. Necrosis (*), delamination in the intima (I), and delamination and coagulation in the media (M) and adventitia (A) are visible (hematoxylin and eosin stain, 60).
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS
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318 Rossi et al
Table III. Predicted odds ratio (OR) for great
saphenous vein (GSV) diameter, body index mass, time,
and power of the depth of vessel wall damage provoked
by endovenous GSV electrocoagulation
95% CI for OR
GSV diameter
Body index mass
Time, seconds
Power, W
OR
Lower
Upper
P value
0.960
1.080
1.260
1.050
0.680
0.945
1.099
1.029
1.357
1.233
1.446
1.071
.8189
.2590
.0009
<.0001
CI, Confidence interval.
electrocoagulation works without tumescent anesthesia, and
this can be an advantage, as it simplifies the method. This is
possible because its peripheral metal head has a coil effect,
and when it leaves the delivery catheter, it opens and stays
in contact with the varicose vein wall intima. As the electric
current passes through the varicose vein wall layers, it generates heat and cellular necrosis.
We previously determined that the time of electrocoagulation is a stronger predictor of varicose vein wall necrosis than the power of energy applied.4 In this study, we
decided to fix the electrocauterization time and accepted
that a 10% vessel perforation ratio would be tolerable.
We found that the best ratio would be 60.4 W 5 seconds, 58.8 W 10 seconds, and 8.9 W 15 seconds.
Corcos et al5 studied GSV fragments subjected to endovenous diode 808-nm laser irradiation. The intimal layer
appeared to be damaged in all the samples. The frequency
of the penetration in the other tissues progressively
decreased from the inner to the external layers. A fullthickness thermal damage involving the adventitia was
observed in 6 (20.69%) of 29 specimens. In our study, the
intima and media layer was damaged in 100% of the cases,
whereas the adventitia layer appeared to be involved in
53% of the cases, and perforation was found only in one case.
The electrocoagulation apparatus here presented has a
low profile, navigates well, and is safe and fully compatible
with current endovascular equipment and treatment techniques. The energy source is the electrosurgery equipment
present in any surgical center. It may become a less costly
and more versatile way of varicose vein thermal ablation.
Despite the excellent results presented, this study has
some limitations. Electrocoagulation seems to work well
and to be safe but was performed in a small venous fragment with maximum 12-mm diameter. The histologic
study analyzed only its immediate effects. We do not
know yet if these acute alterations would be sufficient to
provoke long-term GSV thermal ablation that is necessary
for definitive varicose vein treatment.
CONCLUSIONS
Endovascular electrocoagulation may cause varicose
saphenous vein wall destruction. This effect is correlated
to power, energy intensity, and duration of application
used. The time of application of energy is a stronger predictor of its effects than the power applied. Body mass index
and saphenous vein initial diameter did not correlate with
the depth of vessel wall damage. Determination of the
best time and power of electrocoagulation may help optimize closure rates and the complications index of lower
limb endovenous varicose vein treatment.
AUTHOR CONTRIBUTIONS
Conception and design: FR, NI
Analysis and interpretation: FR, CB, MZ, PM
Data collection: FR, CB, MZ
Writing the article: FR, CR
Critical revision of the article: AS, CR, FR
Final approval of the article: FR, CB, MZ, PM, CO, NI, AS
Statistical analysis: FR
Obtained funding: FR
Overall responsibility: FR
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Fig 3. Best time and power of electrocoagulation index necessary
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Submitted Aug 8, 2013; accepted Nov 9, 2013.