Everything you need to know about blood clots

What are blood clots

A blood clot is a mass of blood that has changed from a smooth-running liquid to a gel-like or semi-solid state. When injured or badly cut, a clot forms when flowing blood comes into contact with certain substances in your skin or in blood vessel walls, to prevent you from losing too much blood. 

Most blood clots will dissolve on their own, however, those that develop in veins and arteries don’t always dissolve and can threaten your life. When a blood clot forms it can be stationary (a thrombosis) or break loose (an embolism) and travel to different areas inside your body

What causes dangerous blood clots? 

According to the University of Cape Town (UCT) Division of Haematology, life-threatening blood clots are caused by abnormalities of the lining of blood vessels (arteries or veins), abnormalities of the clotting factors (proteins that clot blood) or platelets (cell pieces that clot blood) and abnormalities of the flow of blood due to obstruction or immobilisation. 

Types of blood clots 

Arterial clots 

Arteries carry oxygen-rich blood away from the heart to the body. An arterial clot blocks an artery, preventing blood and oxygen from reaching vital organs.

Causes: As per the UCT Division of Haematology, specific causes include the thickening, inflammation and calcification of the lining of arteries due to high blood pressure, high cholesterol, smoking and diabetes, as well as certain diseases. 

Symptoms: As the clot grows and blocks the blood flow, you could experience any of the following: a swollen arm or leg; fingers or hands feel cool to the touch; muscle pain in the affected area; chest pain; numbness or tingling in the arm or leg; loss of colour or weakness in the affected limb. 

Venous clots 

Veins carry blood from the body back into the heart. A venous clot – which develops slowly – is when the blood clot blocks a vein. Three types of blood clots can form in the veins: 
1.    Superficial venous thrombosis – a blood clot that forms close to the surface of the skin. These can be painful and need treatment. 
2.    Deep vein thrombosis (DVT) – a blood clot that forms in a major vein deep – most common in your lower leg, thigh or pelvis. 
3.    Pulmonary embolism – when a clot breaks loose (from a DVT, for instance) and travels to your lungs before getting stuck in the major lung arteries, this can be potentially fatal. 

Causes: According to the UCT Division of Haematology, specific risks for blood clots in the veins include immobilisation like bed rest, high-risk surgery like hip, knee and spinal surgery, long periods of sitting when travelling in planes or buses, hormonal contraceptives, obesity, smoking, late pregnancy, and diseases that cause abnormalities of clotting including cancer, HIV, TB and lupus. 

Symptoms: For a superficial venous thrombosis, symptoms include: painful, swollen and inflamed skin over the affected vein; the vein feels hard or painfully tender to touch. For a DVT, symptoms include: the affected leg is swollen; cramping pain or soreness in the leg, usually in the calf; a heavy feeling in the affected leg; skin surrounding the clot is warm or red. For a pulmonary embolism, symptoms include: chest pain; inability to breathe; pain, swelling or tenderness in your leg. Seek medical attention for this immediately. 

Risk of heart attacks 

One of the main high-risk areas where blood clots can form is in the heart.

“A heart attack occurs when the heart muscle is deprived of blood due to a blockage of a major coronary artery. Several conditions such as diabetes, high blood pressure, being older in age, high cholesterol, smoking and a family history of heart attacks can increase the risk for heart disease and a heart attack,” Dr Ashandren Naicker, an interventional cardiologist at Life Entabeni Hospital in Durban, confirms.

Common symptoms include chest discomfort, which may also be at the jaw or left arm, shortness of breath, sweating, light-headedness and nausea or vomiting. “If you are experiencing these symptoms, go to the hospital immediately, because the sooner you receive the appropriate treatment, the better your chances of reducing the amount of heart muscle damage,” says Dr Naicker. 

After tests and examination, the health professional at the hospital may decide on the most appropriate treatment that will quickly restore the flow of blood to the blocked artery. Medications may include the following: aspirin which reduces blood clotting; thrombolytics or “clot busters” to help dissolve the blood clot, if it’s a severe heart attack; pain medications to help to widen the blood vessels by dilating them; statins to control cholesterol which may have caused the narrowing in the artery that resulted in a blood clot. 

In addition, says Dr Naicker, you may have procedures such as a coronary angiogram and percutaneous coronary intervention (PCI), or alternatively, the doctor may consider emergency bypass surgery, which entails attaching other arteries or veins below the area of the blocked artery, thus “bypassing” the narrowed arteries. 

“Following a heart attack, your doctor may focus on key areas of recovery to rehabilitate the heart muscle. In addition to medications, this may include a supervised programme of exercise, health and dietary education and potential ways to stop smoking,” advises Dr Naicker. For more information on healthy living, visit heartfoundation.co.za

Tips to help prevent getting most blood clots

- Control your blood pressure, diabetes and cholesterol. 
- Lose weight if you are overweight. 
- Stop smoking. 
- Use appropriate contraception. 
- Avoid wearing tight-fitting clothes. 
- Avoid crossing your legs when sitting. 
- Avoid sitting in one position for too long. Move around every hour. 
- Eat less salt. 
- Do exercises recommended by your doctor.
- Take medication your doctor prescribes

Did you know?

In South Africa...
- Over 200 000 patients are diagnosed with DVT a year and up to 20 000 can die from it.
- About 75 000 people suffer from strokes a year, with 20 000 deaths. 
- There are roughly 43 000 heart attack cases a year.