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Venous thromboembolism

When we are healthy, blood flows continually through our circulatory system, which are made up of our heart, arteries, capillaries, and veins.

However, abnormal clotting, or thrombosis, can occur, especially when we are bedridden or immobilised for long periods of time. Certain medical conditions, such as cancer, increase the risk of thrombosis.

Patients having surgery are at risk, especially those having major orthopaedic surgery on a lower limb, such as surgery for hip fracture or hip or knee replacement.

In these patients, surgery stimulates blood coagulation. In addition, the flow of blood returning to the heart from veins in the leg is slowed.

The sluggish blood flow, coupled with possible injury to the lining of the veins, can trigger blood clot formation within a deep vein in the calf. These clots tend to form near valves within the veins.

These abnormal clots can expand upward in the vein, past the knee, to form what is commonly described as a deep vein thrombosis.

If part or all of this growing clot breaks away, it becomes an embolus. After an embolus reaches the heart, it will be pumped out into the lungs. This can cause a medical emergency known as pulmonary embolism.

Symptoms caused by pulmonary embolism, such as a sudden cough, shortness of breath, rapid heart rate, or chest pain, depend on the size of the embolus and where it lodges in the lung. However, symptoms can be vague and resemble those associated with other diseases.

There are treatments to prevent these clots from forming during and after hospitalisation and surgery.

Learn more about prevention of VTE.

Learn more about treatment of VTE.

Atrial fibrillation

Our circulatory system delivers oxygen and other nutrients to all the organs in our bodies. Our hearts serve as pumps, sending blood throughout our circulatory systems.

The heart has 4 chambers: upper chambers, or atria, and 2 lower chambers, or ventricles. With each heartbeat, the atria contract to send blood to the ventricles, which then contract to pump blood out to the lungs (right ventricle) and to the rest of the body (left ventricle).

The heart has 4 chambers: upper chambers, or atria, and 2 lower chambers, or ventricles. With each heartbeat, the atria contract to send blood to the ventricles, which then contract to pump blood out to the lungs (right ventricle) and to the rest of the body (left ventricle).

In atrial fibrillation, or AF, the most common abnormality of the heart's rhythm, the atria contract in a rapid and disorganized way. As a result, the atria do not effectively pump blood into the ventricles.

This ineffective pumping leads to blood pooling in parts of the atria. Clots can form in this slow-moving blood, particularly in an area within the left atrium known as the left atrial appendage.

Clots in the left atrium can be dangerous because they can break loose (forming what is known as an "embolus") and travel through the left ventricle, and then from the heart to the arteries that carry blood to the brain.

The danger is that this embolus can lodge in an artery in the brain, blocking blood flow.

The brain tissue beyond the embolus no longer receives blood. This sudden lack of blood injures the brain cells, causing a stroke.

There are treatments to prevent stroke in patients with atrial fibrillation. These treatments work by preventing the formation of clots.

Learn more about stroke prevention in AF

Acute coronary syndrome

Our hearts pump 60 to 90 times per minute to ensure that there is an adequate supply of blood for every part of our bodies.

The heart is itself nourished by the coronary arteries, which deliver oxygen and nutrients to maintain the constant activity of this muscle.

With advanced age, atherosclerotic plaques develop in the arteries, including the coronary arteries.

Atherosclerotic plaque is comprised of cholesterol-filled cells, inflammatory cells, and other material, which accumulate within the inner wall of affected arteries.

The buildup of plaque can reduce the normal blood supply, limiting the amount of blood that reaches key organs such as the heart and brain.

In acute coronary syndrom (ACS), a coronary artery plaque erodes or ruptures, leading to the formation of a blood clot within the lumen of the vessel.

This clot, or thrombus, can block blood flow in the coronary artery, leading to heart muscle injury, which can potentially lead to death, depending upon the degree of blockage.

Since atherosclerosis usually affects multiple arteries, including other coronaries and arteries that lead to the brain, patients who survive ACS are at risk for further thrombus formation at sites where atherosclerotic plaque forms.

These events could be either recurrent ACS or stroke. There are treatments to prevent recurrent atherothrombosis.

Learn more about acute treatment and prevention of ACS


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