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Foam sclerotherapy (FS) is related to several variables concerning foam
formation and injection, furthermore different material and peri-injection
adjuvant measures may influence the variability of the degree of safety and
efficacy of the use of sclerosant foam. Hence the possible side effects or
complications related to FS should be evaluated also from this point of view.
The presence of a PFO (and possible further related or non-related diseases) may
be a deterrent against the usage of foam, though the right-to-left passage of
foam may happen also through mis-un-known mini/micro a-v pulmonary/peripheral
shunts. Similarly the occurrence of any Valsalva manoeuvre seems to enhance the
haemodynamic significance of the PFO.

In Forlee’s report we highlighted the probable poor quality of the used foam,
which was made with a low concentration drug (hence larger and short-lasting
bubbles are expected), as well as the high volume of the injected air-based foam
was pointed out. Hence the presence of a PFO was one of the co-factors which
gave probably rise to the cerebral ischemic accident, and this should be kept in

Air-based sclerosant foam may be less reabsorbed in the blood stream and through
the endothelium, when compared to the physiologic gases-based foam.
Unfortunately no evidence supports this speculation, though some personal
experiences and some scientific data exist about this matter.

Still a reliable figure of the incidence of the PFO in the general population is
lacking, as well as a clear understanding of the clinical relevance of the PFO
in medicine (and in FS) has not been achieved, due to the fact that the real
calibre of the foramen can be variable with the different pressure gradients

I would not personally recommend the PFO screening (transthoracic or
transoesophageal echocardiograpy ?) in all the patients who should be submitted
to FS, but I would not suggest the usage of sclerosant foam in case of a known
symptomatic/asymptomatic PFO.

The great importance which is given to the presence of a PFO in cases of
migraine or recurrent ischemic cerebral accidents is a relevant issue , though
the scientific community seems to be at the first steps of this new diagnostic

An effort from the scientific community would be most welcome to finalise some
studies on safety of foam sclerotherapy (including the PFO issue) in order to
minimise the complications of this otherwise promising and reliable technique
which proved extremely beneficial from the cost-efficacy point of view.

Attilio Cavezzi

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