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188 Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy
sclerosants. The main factor causing insuffi cient sclerotherapy is the volume
of blood in which the drug is diluted.
With liquid sclerosants, the injection inside a vein segment elevates the
drug concentration to a peak level, followed by a quite fast decrease of
sclerosant concentration. The shape of the concentration curve is ruled by
the speed of injection (mostly related to the pressure exerted on the piston
and the caliber of the needle), the ratio of injected volume, the size of the
vessel, and the blood fl ow. Sclerosis will be triggered only if a minimal
effective concentration of the drug is present for a suffi cient period of
time.
In telangectasias, we expect a prompt rise in concentration and a rela-
tively long plateau effect in which only the drug will be present inside the
vessel. This is clearly observed when performing a spider vein injection
when the needle is held inside the vein for a longer time.
In a large great saphenous vein (GSV) with a signifi cant refl ux, the peak
will be reached more slowly than in the previous example and will be
related to the size of the needle and the fl uidity of the injected material.
The maximal concentration of the liquid sclerosant in that vein segment
will be related to the volume of blood with which it will be diluted. In a
vein where 10 ml of blood is present, an injection of 1 ml of a liquid scle-
rosant like Polidocanol 3% gives a fi nal concentration of drug in the vein
of nearly 0.3%. This explains why sclerotherapy has never been a problem
of drug power for telangectasias where the dilution of drug is virtually
absent and why saphenous sclerosis has always been diffi cult where the
agent is always diluted.
FIGURE 14-1 The production of a CO
2
/O
2
extemporary sclerosing foam.
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Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy 189
The introduction of SF has completely changed this perspective: When
foam is injected, it forms a coherent bolus inside the vein. Due to its prop-
erties, this bolus has controlled and uniform activity and can be controlled
in site for a defi nite time. This will lead to optimal and, for the fi rst time,
controlled sclerosis (Figures 14-2, 14-3 and 14-4).
Foam is a nonequilibrium dispersion of gas bubbles in a relatively small
volume of liquid which contains surface-active macromolecules (surfac-
tants). These preferentially adsorb at the gas/liquid interfaces and are
responsible both for the tendency of a liquid to convert in a foam and for
the stability of the produced dispersion.
The sclerosing foam is a mixture of gas and a liquid solution with ten-
sioactive properties; the gas must be well tolerated or physiologic, and the
bubble size should be preferably under 100 microns. The behavior of scle-
rosing foam is different when injected, if compared to the action of a liquid
solution.
11
The most common mistake with foam is to consider it as a single entity.
In fact, according to the method chosen, it is possible to produce very dif-
ferent foams, with different characteristics, complication rates, and thera-
peutic indications.
FIGURE 14-2 The large, varicose tributary vein is shown here before treatment.
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190 Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy
We can classify foams by a bubble’s diameter (froth, foam, minifoam,
or microfoam) or by the relative quantity of liquid (the shape is the result
of the competition between surface tension and interfascial forces) as wet
foam (nearly spherical bubbles; wetness or the volume fraction of liquid is
over 5%) or dry foam (polyhedral bubbles; the volume fraction of liquid
is below 5%). The wet foam is more fragile, and if a small needle is used
when injecting such foam, most of the structure is lost at the tip of the
needle.
Wet foam has the maximum stability because, when the bubble is
polyhedral, as in dry foams, there is a greater competition between
surface tension and interfacial forces. Uniform diameters also mean more
stability because smaller bubbles empty into larger ones, according to
Laplace’s law, because for smaller diameters there will be a higher internal
pressure.
Another way to classify foam is to consider the standard of production:
It could be low or medium grade for extemporary foam, but is maximal
only for the industrial high standard foam.
Even when it seems very stable, foam is always in evolution. Three
factors will introduce disorder: drainage (draining of liquid from foam),
disproportionation (change in bubble size distribution), and coalescence
FIGURE 14-3 This is the same case as in Figure 14-2, 2 weeks after one treatment with
foam sclerotherapy.
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Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy 191
(fusion of bubbles). These three factors, and the time factor, will lead to
complete dissolution. This dissolution can be slowed in several ways (e.g.,
freezing), but for medical use, it is not necessary because therapeutic prop-
erties are more important than lasting time.
We must therefore stress the role of time between the preparation and
injection of foam, particularly for low standard foam with low drug con-
centration. An ideal injection of air-based SF should be made no more than
15 seconds after generation with the Tessari method.
Another important aspect of foam is its response to forces or rheology:
Foam can exhibit features of different basic states of matter, acting as a
solid, a liquid, or a gas.
In fact, SF exhibits striking mechanical properties because it elastically
resists to pushing if done gently (as inside a vein) or reacts as a liquid if
pushed forcefully in a syringe (syringeability). Moreover, bubbles’ disrup-
tion ultimately converts the foam in liquid and gas.
Sclerosing foam shows peculiar properties: adhesiveness and compact-
ness (with the possibility to manipulate the foam after injection and dis-
placing effect on blood), syringeability (or possibility to be injected with a
small needle without losing its characteristics), greater volume for the same
quantity of liquid agent (possibility to treat longer vein segment), long
FIGURE 14-4 This is the same case as in Figures 14-2 and 14-3, 2 years after foam
sclerotherapy. No further treatments were done.
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192 Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy
duration (long enough for therapeutical action), enhanced spasm genera-
tion (less risk of blood collection inside the sclerosed vein), echovisibility
(Figure 14-5), enhancement of sclerosing power with reduced drug dose
and concentration, and selectivity of action on endothelium (lesser risk in
case of extravasation).
Again, it must be stressed that each type of foam has different properties
and characteristics.
CLINICAL APPLICATIONS OF FOAM
SCLEROSANTS
Foam can be used in every kind of classical sclerotherapy. Moreover,
new and exciting indications have been tried with success.
In our experience, inguinal neovascularization and saphenous trunks
are very good indications, and mid-term results are encouraging.
The fi rst series on saphenous trunks treated with Cabrera’s microfoam
was published in 1997 and reported on 261 great saphenous veins treated
with echoguided injection of standardized microfoam.
12
In 1999 the fi rst paper in English literature on foam sclerotherapy was
published,
13
and in 2000 Frullini and Cavezzi presented their results on 167
large veins treated with echosclerosis, utilizing foam with very good
results.
14
FIGURE 14-5 This ultrasound scan photo shows the echovisibility of the GSV with
sclerosant foam, showing the large acoustic shadow after foam injection.
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Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy 193
The treatment with STS or POL foam is generally performed in saphe-
nous trunk with echo-color-Doppler guide.
Sodium tetradecylsulfate 3% or Polidocanol 3% are usually chosen to
prepare a thick foam with Tessari’s or Frullini’s method. According to the
Tegernsee Consensus paper,
15
up to 10 ml of this foam can be used, but
5 ml is enough to treat most GSVs less than 10 mm if a short cannula is
used, and the leg is elevated in order to speed up the fl ow in the deep system
and reduce the caliber of superfi cial veins.
A maximum of 10 ml POL or STS 3% of extemporary air foam is rec-
ommended to keep the treatment safe. Industrial grade foam can be used
safely in larger volumes, but the coalescence rate of extemporary air foam
is not yet proven to be controlled enough to perform a safe injection
exceeding 10 ml of foam. On the contrary, CO
2
-based extemporary foam
seems to have higher safety even when larger volumes are injected.
16
In 2000, Tessari proposed the use of a ureteral catheter to inject SF in
the GSV.
17
A balloon catheter for foam sclerotherapy has been recently
produced. The balloon is used to temporarily occlude the junction during
treatment in order to prevent foam passage in the deep system.
17
In fact, this injection must be considered as something very different
from simple needle or short cannula injection; the presence of a balloon
makes this an injection against pressure, as the blood cannot fl ow freely
from the GSV to the femoral vein and a gradient of pressure will direct all
the blood to thigh perforators and in distal tributaries. This could be an
explanation for the relatively larger incidence of deep vein thrombosis
(DVT) using the balloon catheter to deliver SF.
An injection with more pressure could theoretically achieve better
results in terms of long-time occlusion rate, as a deeper penetration of
sclerosant in the vein wall could produce a better sclerosis.
I have only limited experience with such catheters with good results, but
the time for treatment is almost fi ve times that of injection of SF with a
plain needle, and the cost is much higher. The role of these catheters may
be very important for larger veins (>14 mm) where the caliber of the vessel
does not allow easy treatment.
Telangectasia is, in my opinion, the worst indication for sclerosing foam,
but this treatment is widely utilized. I generally prefer to use liquid scle-
rosants (POL) for standard telangectasias. POL foam (or very seldom STS)
is reserved for resistant cases or for telangectatic matting that, on the con-
trary, is a very good indication for SF made with POL foam 0.25% to
0.5%.
Tessari’s foam is diffi cult to push in these small vessels, but reducing the
liquid-to-air ratio to 1 : 2 or 1 : 1 ameliorates quality and durability of foam,
enhancing safety and results. Moreover, glass syringes may create a safety
problem due to poor sterilization.
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194 Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy
Complications of foam sclerotherapy are similar to those of liquid scle-
rosants with few exceptions.
The use of air in production of SF was reported to cause a stroke in one
patient with a patent foramen ovale (PFO). This condition is present in
almost 25% of the normal population and is usually linked to a history of
migraine; therefore, a specifi c question about migraine must always
be directed to the patient who is to have foam sclerotherapy. If I have a
patient with a history of migraine with aura, I generally use a different
treatment.
A report on a reversible but long-lasting neurological defi cit has been
published. In this case, a very low standard foam (POL 0.5%) in too large
a volume (20 ml) was used in the treatment of a GSV of medium size.
19
No
data were given on the time elapsed from the preparation of the SF and
the injection. There is probably no other report of such a complication
when SF is properly used.
It must be stressed again that concentration of drug and volume are
directly linked (i.e., a larger volume of foam has better quality if a higher
concentration of drug is used). With regard to this, I can reach up to 10 ml
of foam in a single session only if a 3% POL is used. STS 3% is never used
in more than 5 ml as in plastic syringes because it has less stability than
POL in higher concentrations.
20
Some reports have stressed a reduction of neurologic side effects using
CO
2
alone or in combination with O
2
in a ratio of 70% to 30% in the
preparation of SF with the Tessari method.
The role of these different factors has not yet been analyzed. Strejcek
demonstrated the presence of circulating endothelial cells (CEC) after
sclerotherapy with liquid. The number of CECs after foam sclerotherapy
is signifi cantly greater. What this means is not known. We have not studied
the role of circulating cells or mediators released from the area treated
with sclerosants.
21
Among the major complications, a partial deep vein thrombosis (DVT)
has been reported after sclerotherapy for varices.
22
However, in every case,
the DVT was asymptomatic and without sequelae at 3 months. Unfortu-
nately, varicose vein patients treated with classical sclerotherapy or stan-
dard surgery are rarely studied with duplex ultrasound after the treatment
as are the patients treated with echoguided injections. Therefore, a com-
parison with SF patients cannot be made.
Lowering the concentration of the sclerosing drug used for foam
generation and avoiding large volume injections in short saphenous vein
(SSV) (<2.5 ml) will be extremely important to lessen the chance of a
DVT. This has to be considered a rare and generally limited complication,
but the need for routine color Doppler control after treatment has to be
stressed. It is extremely important to clearly identify before treatment
those cases in which a gastrocnemius vein empties into the terminal part
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Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy 195
of the SSV. In those cases, an increased risk of sclerosis of the deep vein
is present.
Minor complications have often been reported with foam, as is also true
with liquid sclerosants. The unique exception is with the treatment of
telangectasias, where pigmentation and skin necrosis have been reported
even by experienced doctors. This is due to the higher sclerosing power of
foam.
PHILOSOPHICAL CONCLUSIONS
The treatment of varicose veins is changing. Many new options are now
offered to patients and doctors: surgery, thermal ablation (endovenous
laser ablation, radiofrequency closure, and steam obliteration),
23
and endo-
venous chemical ablation (foam sclerotherapy). I have several observations
on the theoretical premises of thermal ablation (what happens in a very
thin vein, what amount of smoke is produced inside the vein, and how much
gets to the right heart, etc.), but I would like to say something on the whole
philosophy of these new methods.
We need a treatment that is capable of achieving good results in a safe
and less invasive manner than surgery. The technique should be capable
of treating tributaries at the same time with the same method as the saphe-
nous vein. The method should be cheap, easy to learn, and repeatable in
case of recurrence.
Thermal techniques are only a different way of treating the saphenous
trunk using a method that is something very similar to surgical interven-
tion: The patients are in an (semi)operating room, a sterile fi eld is pre-
pared, and anesthesia is given. Then we gain venous access and place a
catheter in the GSV. Phlebectomies will be done on tributaries in most
cases. The only difference is that, in the stripping operation, the same fi ber
(stripper) is retrieved, and a junctional ligature is made. Moreover, gentle
invaginating stripping under local anesthesia seems to me less invasive,
when properly done, than laser ablation or radiofrequency closure.
Considering that almost 50% of GSV insuffi ciency is due to terminal
valve incompetence alone, a proper indication for treatments that do not
include sapheno-femoral junction ligation will be found in only a few
cases.
If a different treatment of saphenous insuffi ciency is to be found, at this
time, only foam sclerotherapy has the ideal prerequisites: It is cheap, time
saving (10 minutes for the whole procedure), and easy for a trained doctor
to perform; plus, tributaries are treated at the same time as the saphenous
vein, and a return to daily activity is resumed after a 15-minute walk. No
anesthesia is required at all, and post-treatment pain is absolutely absent.
The volume of air or physiologic gas injected with foam is probably far less
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196 Treatment of Chronic Venous Insuffi ciency with Foam Sclerotherapy
then the uncontrolled volume of smoke produced by the laser in the venous
system.
Moreover, venous insuffi ciency is not simply a defect that must be elimi-
nated. It is a true disease with a natural evolution. Every treatment is
capable, when correctly performed, to bring the leg back to a prior condi-
tion, but no treatment will stop the natural evolution of the illness. The
simplicity of foam sclerotherapy makes the treatment easily acceptable to
patients, even if more sessions are needed in subsequent years to stabilize
the condition. Neither surgery nor thermal ablation can claim the same
benefi ts.
The ultimate study with a comparison of different methods is still
lacking, and the few studies available do not compare homogeneous cases
or properly done treatments. It must be stressed that alternative treatments
to surgery must not unnecessarily complicate the work of doctors and the
lives of patients in a search for a fashionable procedure with indefi nite
advantages over standard treatment. If foam sclerotherapy will demon-
strate in large Good Clinical Practice (GMP) studies that it is capable of
achieving results similar to surgery, a consistent step toward the control of
venous insuffi ciency will have been made.
At this stage, it is extremely important that foam sclerotherapy is used
in a wise manner respecting the guidelines of the Tegernsee Consensus
conference: The 10-ml volume limitation with air must be respected or,
when a higher volume is needed, CO
2
/O
2
sclerosing foam must be used.
My hope is that national health systems and insurance companies ulti-
mately understand that venous insuffi ciency is not just a cosmetic condition
but a true disease, with consistent morbidity and mortality and that, at least
in my opinion, foam sclerotherapy (also called endovenous chemical abla-
tion) is going to become the ultimate treatment for venous insuffi ciency,
replacing every other treatment for most cases.
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