2. Definition
• Thrombosis is a serious condition where a clot
forms inside a blood vessel (an artery or vein)
in your body or sometimes inside of your
heart. This is dangerous because clots that
form inside blood vessels can block blood
flow. They can also break free and travel
elsewhere in your body, and if a clot gets stuck
in a critical location like your lungs or brain,
that can cause life-threatening emergencies.
3. Causes of Thrombosis
• Thrombosis is caused by blood clots forming
in deep veins, most often in the legs. Blood
clots can form whenever there is any
condition that prevents blood from circulating
or clotting normally. For example, they can
happen to people who tend to lack physical
movement after an accident, injury, surgery,
or during bed rest.
4. Symptoms of Thrombosis
• The two main symptoms of thrombosis are pain and
swelling. The pain in the affected area (usually the leg)
begins like a cramp and may intensify. Swelling occurs in
the vicinity of the blood clot. In rare cases, there may be no
symptoms at all.
• The most serious symptoms may result from the formation
of a pulmonary embolism, when arteries in the lungs
become blocked by a blood clot. This can include sudden
difficulty breathing, chest pain that gradually intensifies or
gets worse when breathing in, dizziness, lightheadedness,
increased heart rate, and coughing up blood. All symptoms
require physician attention, but a pulmonary embolism
requires immediate medical attention.
5. Types of thrombosis
• Arterial thrombosis
• This is thrombosis that happens in arteries, which are
blood vessels that carry blood from your heart to the
rest of your body. Arterial thrombosis is the most
common cause of heart attacks and strokes.
• Venous thrombosis
• This is thrombosis that happens in veins, which are
blood vessels that carry blood back to your heart from
your body. Venous thrombosis is the most common
cause of pulmonary embolism (blood clot in your lung).
6. Arterial Thrombosis
• Every cell, tissue and organ in your body depends on a steady supply of blood to
survive, and arteries are how they get that supply. A clot that blocks an artery will
cause a problem called ischemia , which is when cells start dying because they
aren’t getting the blood flow they need.
• Early symptoms of ischemia from a blood clot include:
• Visible color changes on your skin. Areas beyond the blockage (meaning the clot is
between that area and your heart) will typically look paler than other areas.
• Temperature change in the affected area. Lack of blood flow will make the
affected part of your body feel cooler to the touch than other areas.
• Weakness. This can also involve not being able to move the affected body part.
• Numbness or tingling (pins and needles feeling). This can also sometimes involve
pain in the affected area.
• The symptoms that follow usually are more severe. They include:
• Blisters, wounds or sores. These can happen when skin wears away or tears open.
• Skin sloughing (pronounced “sluffing”). This is when skin falls away or separates
from the tissue underneath.
• Necrosis. This causes skin and tissue to die and turn black. The area of dead or
dying tissue will spread gradually outward.
7. Venous Thrombosis
• Blockages of veins, which are also very common in
your legs, limit how quickly blood can make its way
back to your heart. That puts too much pressure on
your veins, which causes fluid and blood to leak out of
them and into surrounding tissues.
• When this happens, symptoms typically include:
• Color changes, especially redness or darkening of the
affected area.
• Pain, especially around the affected area.
• Swelling from the fluid buildup.
• Skin that feels noticeably warmer than other areas.
8. What causes thrombosis
• Thrombosis can happen for many reasons, but certain conditions are more likely to
cause clots to form. These conditions fall under the following types or categories.
• Circulatory and heart problems
• Conditions like atherosclerosis, where arteries stiffen because of a buildup of
plaque (a waxy substance related to cholesterol) inside them, often cause clots.
This happens when a clot forms over a rupture or break in a section of plaque. This
is often what causes heart attacks.
• Other similar problems include:
• Heart valve disease. Problems with your heart valves, such as mitral valve stenosis
(narrowing), can make clot formation more likely.
• Atrial fibrillation. This is a condition where the upper chambers of your heart beat
so fast, they can’t pump blood correctly. Blood that lingers in these chambers can
form clots, which can then travel elsewhere in your body. Atrial fibrillation is a
common cause of stroke.
• High blood pressure and high cholesterol. Both of these conditions, over time, can
damage your heart and blood vessels, limit circulation and make it easier for clots
to form.
9. • Blood clotting problems
• Several conditions and problems can cause your blood to clot more easily. These conditions can
happen for the following reasons:
• Inherited or genetic clotting disorders. Several genetic conditions, which you inherit from your
parents, can make your blood clot too easily. These conditions are usually treatable but typically
aren’t curable.
• Other medical conditions. Certain types of cancer can make blood clots much more likely. Other
conditions like HIV, inflammatory bowel syndrome or immune disorders can also cause clotting
problems.
• Medical procedures. Surgeries can cause your body to try to clot in ways that can be harmful.
That’s why medical providers often prescribe blood-thinning medications after surgery or other
types of procedures.
• Medications. Certain medications can cause your blood to clot more easily. In some cases, that’s on
purpose. In others, it can be an unexpected and unintended side effect of or reaction to a
medication. Certain types of hormonal treatments, including those used in birth control, can also
cause blood clotting issues.
• Lack of activity. Sitting or lying still for long periods can cause your blood to circulate poorly in
some parts of your body, especially your legs. That makes it easier for clots to form. This often
happens to people on long airplane or car trips, people who have some form of paralysis or who
are on bed rest. It can also happen to people who aren’t physically active, especially those who sit
for extended periods.
10. Treatment
• Anticoagulation
• Warfarin and vitamin K antagonists are anticoagulants that can be taken orally to reduce
thromboembolic occurrence. Where a more effective response is required, heparin can be given
(by injection) concomitantly. As a side effect of any anticoagulant, the risk of bleedings increased,
so the international normalized ratio of blood is monitored. Self-monitoring and self-management
are safe options for competent patients, though their practice varies.
• Thrombolysis
• Thrombolysis is the pharmacological destruction of blood clots by administering thrombolytic drugs
including recombinant tissue plasminogen activator which enhances the normal destruction of
blood clots by the body's enzymes. This carries an increased risk of bleeding so is generally only
used for specific situations (such as severe stroke or a massive pulmonary embolism).
• Surgery
Arterial thrombosis may require surgery if it causes acute limb ischemia
• Endovascular treatment
Mechanical clot retrieval and catheter-guided thrombolysis are used in certain situations.
• Antiplatelet agents
Arterial thrombosis is platelet-rich, and inhibition of platelet aggregation with antiplatelet drugs such
as aspirin may reduce the risk of recurrence or progression.
11. Mechanism
• Hypercoagulability
• Hypercoagulability or thrombophilia, is caused by, for example, genetic
deficiencies or autoimmune disorders .Recent studies indicate that white blood
cells play a pivotal role in deep vein thrombosis, mediating numerous pro-
thrombotic actions.
• Endothelial cell injury
• Any inflammatory process, such as trauma, surgery or infection, can cause damage
to the endothelial lining of the vessel's wall. The main mechanism is exposure
of tissue factor to the blood coagulation system.Inflammatory and other stimuli
(such as hypercholesterolemia )can lead to changes in gene expression in
endothelium producing to a pro-thrombotic state. When this occurs, endothelial
cells downregulate substances such as thrombomodulin ,which is a key modulator
of thrombin activity..The end result is a sustained activation of thrombin and
reduced production of protein C and tissue factor inhibitor, which furthers the pro-
thrombotic state.
• Endothelial injury is almost invariably involved in the formation of thrombi in
arteries, as high rates of blood flow normally hinder clot formation. In addition,
arterial and cardiac clots are normally rich in platelets–which are required for clot
formation in areas under high stress due to blood flow.
12. • Disturbed blood flow
• Cancer-associated thrombosis can result from:
• (1) stasis, i.e., direct pressure on blood vessels by the tumor mass,
poor performance status, and bed rest following surgical
procedures;
• (2) iatrogenic, due to treatment with antineoplastic medications;
and
• (3) secretion of heparanase from malignant tumors that results in
degradation of endogenous heparin.
• Causes of disturbed blood flow include stagnation of blood flow
past the point of injury, or venous stasis which may occur in heart
failure or after long periods of sedentary behaviour, such as sitting
on a long airplane flight. Also, atrial fibrillation ,causes stagnant
blood in the left atrium (LA), or left atrial appendage (LAA), and can
lead to a thromboembolism.
