A little bit about the pathogenesis: You've
seen this slide before. As you heard, 90%
of DVTs and pulmonary emboli occur in the
veins of the leg. Often, they start as very
small clots in the popliteal vein, and often,
they will dissolve and heal without any problem.
But once they get up into the femoral vein,
which is a lot of people—you see, 42% of
people—there is a greater likelihood of
the clot growing. And then you can see, once
it gets up into the common femoral vein or
the iliac vein, inferior vena cava, there's
a very significant chance that a large mass
of clot will embolize to the lung and might
prove to make the patient either very sick
or even die. Just to emphasize one more time:
The consequences of venous thromboembolism—pulmonary
embolism—can be fatal. It can cause a very
serious illness, acute morbidity. Once you've
had one, you're at high risk for more. Thrombophlebitis
itself, as you know, can lead to the postthrombotic
syndrome, with edema and ulcers and, in a
rare case, even amputation.
So thrombophlebitis is defined as the presence
of a thrombus in the vein. It's accompanied
by inflammation in the vessel wall. It can
happen, of course, in superficial or deep
veins. The dangerous one is one that occurs
in deep veins, not in the superficial veins.
Of course, the danger is pulmonary embolism,
and we've already talked about all the things
that can lead to deep venous thrombosis, including
long periods of sitting or standing, or a
long plane trip. We've also already mentioned
the postthrombotic syndrome. This is a long-term
complication of DVT and venous insufficiency,
where the internal veins are not working well.
The valves are not working. Blood pools. The
vein dilates. There's a great tendency for
a blood clot to form. Edema forms. There's
poor skin nutrition, and often, ulcers develop.
The blood proteins and other blood products
(hemoglobin) are deposited in the tissues,
giving a brown discoloration, and the ulcers
can be exceedingly difficult to heal, taking
many months to heal with constant therapy.
Again, just to reiterate for how common DVT
is: Patients in the United States in one year
will have clinically evident venous thromboembolism—a
total of 900,000 patients. And the deaths
there are about… that are due to pulmonary
embolism are about 300,000. And the annual
incidence of venous thromboembolism increases
by age and sex, as you can see in the graph.
Particularly as patients get above age 55
to 65, there's a marked increase in venous
thromboembolism. Males a little more than
females, but not very, very much difference.
Again, a huge increase. This data comes from
the Worcester Vein Study in Worcester, Massachusetts.
The University of Massachusetts Medical Center
has been studying all cases of DVT/PE in Worcester
County over many years.
The symptoms: I think we've already talked