Description and summary Blood
clotting is a natural process that allows the blood to thicken and form a clot
of blood cells and fibrin strands to stop the bleeding when blood vessel is
severed. If the body did not have the ability to clot blood, then people would
bleed to death after even a minor cut.
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However, when a blood clot forms in an artery, blocking
the blood flow to the heart muscle or the brain, a heart attack or stroke can
follow. Or when blood lingers in one of the heart’s chambers (due to certain
heart conditions), a piece of the blood clot can be pumped from the heart,
travel through the bloodstream, and lodge in either an organ or an artery,
cutting off the blood supply from that point. This can cause an embolism.
There are many other conditions related to blood clots.
Coronary thrombosis is a blood clot in coronary arteries leading to a heart
attack, deep vein thrombosis is a blood clot in the leg veins, pulmonary
embolism is a blood clot in the lungs, retinal vein occlusion is a blood clot in
a vein of the eye,
Why would a blood clot form in your
body? Three primary factors can predispose a person to the formation
of a blood clot (thrombus): 1. Roughness or scar tissue along the inner
walls of a blood vessel. This endothelial injury on its own can lead to blood
clotting in the heart chambers (due to damage to the inner lining after a heart
attack or to infection in the heart valves) or in the arteries. Blood clots can
form in arteries where the inner lining of the vessel is damaged by
atherosclerotic plaque, or where it is injured by trauma or inflammation. The
injury may be caused by hypertension, turbulent flow over damaged heart valves
or bacterial endotoxins. Elevated blood cholesterol or homocystine levels,
radiation and cigarette smoke can cause this damage. All endothelial
damage will lead to the exposure of underlying collagen and this will be the
first step in platelet aggregation and formation of a blood
clot. 2. Pockets of sluggish blood flow and turbulant
blood. Turbulance causes endothelial injury and also lead to countercurrents and
pockets of sluggish flow, leading to the build up of clots. This can happen at
sites of artherosclerotic plaques, sites of abnormal arterial dilations (called
aneurysms), after a previous heart attack (causing damage to the inner walls and
to the heart muscle, leading to sluggish flow) and due to mitral valve damage
(after rheumatic heart disease – a common problem in South Africa). Valve damage
coupled with atrial fibrillation can lead to sluggish flow. Certain blood
disorders like a high red cell count, sickle cell anemia, can thicken the blood
and lead to slower blood flow. 3. Hyper-sticky blood is uncommnon, but
mainly related to genetic blood clotting disorders (including the factor V or
Leiden mutation, which can be an indicator of risk for Deep Vein Thrombosis).
What are the causes of blood clots?
Injury to the inner walls of the blood vessels and sluggish blood
flow, are associated with certain conditions. People with the following
condtions are more at risk to develop blood clots: · Atherosclerosis
· Trauma to a blood vessel due to an accident, surgery, fracture or
burn · Recent heart attack or stroke · Heart valve
disease · Heart failure · Infection · Auto-immune
disorders like lupus (SLE) or rheumatoid arthritis) · Bleeding
disorders like hemophilia · Inflammatory bowel disease · Certain
cancers · History of varicose veins or other vascular
diseases · Pregnancy · High blood pressure · Elevated
platelet levels · Atrial fibrillation · Genetic factors such
as inherited tendency for deep vein thrombosis
In addition, the following lifestyle risk
factors can increase the chances of developing a blood clot. These risk factors
include: · Smoking · Obesity (more than 10 kg
overweight) · Lack of exercise · Bedrest more than 4
days · Use of the Pill · High dosages of
oestrogen · Sitting in one position for a prolonged time (as in
anaeroplane)
How are blood clots diagnosed?
Diagnosis of a blood clot begins with a complete medical history,
physical examination, en several blood and other tests.
How can blood clots be treated? The
treatments for a blood clot will depend on whether the clot has formed in
a vein or artery, the location and size of the clot, and the patient’s
general health. 1. If it has formed in an artery and has caused a
heart attack or stroke, then clot busters (ike streptokinase) may be used for
the first two days to dissolve the blood clot. They must be given within three
hours of the heart attack or stroke. More invasive procedures may be indicated,
where a catheter is inserted and delivers thrombolytic enzymes directly to the
blood clot. Higher concentrations of enzymes can be used. This medication is
followed by treatment with anticlotting medication (like heparin or warfarin) to
prevent more blood clots from forming.
2. If a blood clot forms in a vein, you face the risk
that the blood clot can travel to the lung and cause a life-treatening pulmonary
embolism. In this case blood clots are usually treated with a combination of
heat, painkilling medications, anti-clotting medication and and
elevation/bandaging of the affected area to reduce swelling.
In extreme situations, surgery may be required to remove
a clot before it starts to travel to the lungs.
Can blood
clots be prevented? Prevention is important, particularly in people
prone to blood clots. The risk group for blood clots in arteries
includes: · People with mitral valve damage, · People
with an enlarged heart · People with heart failure The best
prevention is regular exercise, effective treatment of other heart-related
medical conditions, and anti-clotting medication. This can be an aspirin daily.
The risk group for developing blood clots in a vein include:
· People with varicose veins, · Obese people · People
with chronic heart failure · Or people with habits or work that require
them to stayi n one position for long periods of time. The best prevention
is regular exercise, movement or stretching, maintaining optimal weight, and not
smoking. Peope should avoid sitting with crossed legs and wearing tight garments
below the waist. To reduce the risk of blood clot formation after surgery
(particularly knee, shoulder or hip surgery) during the recovery period, your
doctor may prescribe aspirin or other anti-clotting medication to prevent blood
clots. Doing calf and leg exercises before surgery and as soon as possible
after surgery can be helpful in blood clot prevention.
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