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bubble contrast and a provocative
maneuver such as a Valsalva
or sniffing. Other methods are
suboptimal.
INTERPRETATION OF
FINDINGS
A spontaneous shunt is a passage
of contrast bubbles from the right
atrium to the left atrium without
a provocative maneuver. This is
considered to very likely represent
an increased risk for DCS in cases
when dives result in a lot of VGE.
A large provoked shunt means
that a lot of VGE are passing
through after a Valsalva maneuver
or sniffing. It is likely to open
with any kind of straining and is
recognized as a risk factor for the
previously listed forms of DCS.
The presence of smaller shunts
is associated with lower risk that
should be evaluated on a case-by-
case basis. It is important to note
that the detection of a PFO in divers
who suffered an episode of DCS is
not proof that the PFO caused that
specific episode of DCS.
RISK MITIGATION
Divers with a diagnosed PFO
that’s likely to be associated with
increased risk of DCS should
consult a dive physician and
consider options that best suit
their needs and diving styles with
a solid understanding of the risks
and benefits of each option. The
options are as follows:
1. Stop diving.
2. Dive more conservatively to
reduce occurrence of VGE,
and do not strain after diving
to avoid opening the PFO and
provoking RLS.
3. Close the PFO.
Conservative diving includes
strategies to reduce the risk of
significant venous bubbles postdive
and of shunting bubbles through
the PFO. Since there is significant
variability in VGE occurrence
among divers and in the same
diver over time, discuss options
with a dive medicine expert before
making any decision. For more
details about conservative diving,
see
Diving.
The closure of a PFO may reduce
the risk of DCS, but it is not a
guarantee that DCS will not occur
in the future.
Deep and long dives may
cause DCS without VGE passing
to the arterial side. Even in the
absence of a PFO, VGE may pass
to the arterial side through shunts
within the lungs that tend to open
with exercise, hypoxia and beta
adrenergic stimulation and close
with hyperemia.
RETURN TO DIVING AFTER A
PFO CLOSURE
Diving should not be resumed
before full closure is confirmed
with another contrast
echocardiogram at least three
months after the closure. Divers
should not return to diving as long
as there is a need to take potent
antiplatelet medications. If the
test at three months or more after
closure shows complete closure
and the diver is prescribed only
aspirin or nothing for clotting
prevention, diving can be resumed.
Divers should always remember
that the main factor causing DCS
is the dive exposure itself — the
depth, time and ascent rate. With
a significant exposure, anybody
is at risk of DCS. Most people
who get DCS do not have a PFO.
Divers with a complete closure
of PFO may avoid DCS episodes
that they may have had in the
past, but if they engage in extreme
diving, their risk of DCS will be
commensurate. AD
(excludes Atlantis Azores), taxes and service charges.
Rates are per person, double occupancy as noted and
subject to availability and standard terms and condition.
Valid for varying dates.
CSOT#2111993-40 • WSOT#603254369 • FSOT#38781
Beth Watson
800-328-2288
MOALBOAL
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Atlantis Dive Resort Puerto Galera
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