detroit diver
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Apr 26 (Reuters Health) - Before birth a connection called the foramen
ovale exists between the right and the left side of the heart that allows
blood to bypass the lungs. Usually this connection closes after birth, but
new research indicates that an open or "patent" foramen ovale (PFO) may be
common in one group of adults -- scuba divers.
In divers, a PFO can allow tiny gas bubbles to pass from the vein side of
the body to the artery side, leading to certain types of "the bends," also
called decompression sickness, according to the report in The American
Journal of Cardiology.
The observation that some people have uneventful dives for many years and
then suddenly become more susceptible to the bends, led Dr. Peter
Germonpre, from the Military Hospital Brussels in Belgium, and colleagues
to hypothesize that the foramen ovale was not closing as expected.
To test this theory, the researchers used cardiac ultrasound to look for
PFO in 40 divers on two occasions 7 years apart. The group included 16
subjects who had experienced the bends and 24 who had not.
PFO was diagnosed and graded according to the number of test bubbles that
passed through the opening during ultrasound -- the more bubbles that
passed, the bigger the opening. With a normal foramen ovale, no bubbles
should pass, meaning that the opening had closed.
On initial evaluation, 20 subjects were diagnosed with PFO and 20 had a
closed opening. At follow-up, 21 subjects were diagnosed with the condition
and 19 had a closed opening.
Although the increase in subjects with PFO was slight, there was a
pronounced shift to more severe PFO. For example, the number of subjects
with the largest PFOs, known as grade 2, increased by six between the two
assessment periods.
"To our knowledge, this is the first (forward-looking) study to actually
document the increase in PFO size in humans, using a standardized and
reliable...technique," the authors point out. Further research is needed to
determine exactly why a PFO does not follow its typical course in some
divers, they add.
SOURCE: The American Journal of Cardiology, April 2005.
Publish Date: April 26, 2005
http://dx.doi.org/10.1016/j.amjcard.2004.12.026
from the link above: "Unexpected but significant increases in the prevalence and size of PFO were found, suggesting a possible increasing risk for decompression sickness in these divers over time."
ovale exists between the right and the left side of the heart that allows
blood to bypass the lungs. Usually this connection closes after birth, but
new research indicates that an open or "patent" foramen ovale (PFO) may be
common in one group of adults -- scuba divers.
In divers, a PFO can allow tiny gas bubbles to pass from the vein side of
the body to the artery side, leading to certain types of "the bends," also
called decompression sickness, according to the report in The American
Journal of Cardiology.
The observation that some people have uneventful dives for many years and
then suddenly become more susceptible to the bends, led Dr. Peter
Germonpre, from the Military Hospital Brussels in Belgium, and colleagues
to hypothesize that the foramen ovale was not closing as expected.
To test this theory, the researchers used cardiac ultrasound to look for
PFO in 40 divers on two occasions 7 years apart. The group included 16
subjects who had experienced the bends and 24 who had not.
PFO was diagnosed and graded according to the number of test bubbles that
passed through the opening during ultrasound -- the more bubbles that
passed, the bigger the opening. With a normal foramen ovale, no bubbles
should pass, meaning that the opening had closed.
On initial evaluation, 20 subjects were diagnosed with PFO and 20 had a
closed opening. At follow-up, 21 subjects were diagnosed with the condition
and 19 had a closed opening.
Although the increase in subjects with PFO was slight, there was a
pronounced shift to more severe PFO. For example, the number of subjects
with the largest PFOs, known as grade 2, increased by six between the two
assessment periods.
"To our knowledge, this is the first (forward-looking) study to actually
document the increase in PFO size in humans, using a standardized and
reliable...technique," the authors point out. Further research is needed to
determine exactly why a PFO does not follow its typical course in some
divers, they add.
SOURCE: The American Journal of Cardiology, April 2005.
Publish Date: April 26, 2005
http://dx.doi.org/10.1016/j.amjcard.2004.12.026
from the link above: "Unexpected but significant increases in the prevalence and size of PFO were found, suggesting a possible increasing risk for decompression sickness in these divers over time."
