with its potential for thromboembolism.
Of course, when there's intravascular coagulation
or blood clotting, the treatment is going
to be intravenous and/or subcutaneous injection
of an anticoagulant—for example, heparin
or an oral agent (warfarin) or one of the
new agents (dabigatran, rivaroxaban, apixaban,
or edoxaban). All of these have been approved
and are very effective for treating DVT and
pulmonary embolism. What they do is they prevent
the clot from propagating, and then the body's
own enzymes break up the clot slowly over
time. One can give heparin that's unfractionated—a
big molecule. That's associated with a little
more complications than the newer form of
heparin, which is only partial… part of
the heparin molecule which causes the anticoagulant
effect. The major problem, major side effect,
is bleeding. When you thin the blood, there's
always a risk for bleeding internally or externally.
One can do surgery or catheter removal of
the clots, or one can actually put a filter
in the vena cava to prevent the clot from
coming up. This is only done in critically ill
or high-risk patients. And finally, where
there's a huge amount of clot, we can give
thrombolytic drugs that are known as clot
busters. They dissolve the clot. They're actually
chemicals that are based on the body's own
thrombolytic enzymes, but in much higher concentration,
and therefore are very effective at dissolving
Chronic therapy: If the patient has one of
these hypercoagulable inherited factors, it
may be that they need anticoagulants for the
rest of their life. But in general, usually
six months to a year of anticoagulant therapy
and then stopping and seeing what happens.
I've already mentioned that there's warfarin.
Warfarin is a thinner that requires frequent
blood tests to make sure that the level is
adequate or not excessive. But the new oral
apixaban, and edoxaban—do not require blood
tests. They don't require special dietary
restrictions, as with warfarin. And they are
very, very popular. Again, because they're
new, they're more expensive. In the United
States, most insurance companies cover these
new agents with only a modest additional co-pay,
and many patients are choosing this instead
of warfarin, the older therapy.
And, of course, exercise: frequent walking.
The muscle pump helps to milk the veins and
prevent stasis. Compressive stockings (we've
talked about that) again help prevent venous
stasis. By the way, we talked about the fact
that when you've had one episode, you're markedly
likely to have another episode. Here, you
see from a study that followed patients who
had a first episode of DVT with pulmonary
embolism for eight years, and you can see
what happened. In the first year, there was
already 5% had a recurrence. The second year,
10%. And already, by the eighth year, almost
30% of the patients had had a recurrence.
So this is a major risk factor for further
DVT/PE when you've had one episode.
In terms of prevention, of course, we want
to try and prevent injury to the vein. We
want to try and prevent hypercoagulability,
and we want to try and prevent stasis. Some
patients who are high-risk will have anticoagulants
after delivering a baby (postpartum) and early
ambulation after surgery. Antiembolism stockings:
We've talked about that, the compressive stockings.
Some patients use pneumatic compressive devices
when they're in the hospital to keep squeezing
the calves, to keep squeezing the blood out.
We can elevate the leg, to cause better venous
emptying, every hour or so. Permanent elevation
of the leg also helps to prevent stasis. And
then after surgery or any injury, the sooner
one gets the patient to ambulate and get the
muscle pump working on the veins, again, the