Arterial Occlusion

Image: Diagram illustrating arterial occlusion and how blood flow is obstructed in an artery, leading to potential tissue damage. Image credit: SlideServe (www.slideserve.com).

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Diagnosis | Management

Definition

Arterial occlusion is a condition where the blood flow through an artery is blocked or restricted, typically by a clot or a build-up of plaque. This can occur in any artery in the body but is most commonly seen in the coronary (heart), carotid (neck), and peripheral (limb) arteries. When an artery is occluded, the tissue or organ it supplies with blood may not receive enough oxygen and nutrients, leading to tissue damage or death. This can lead to serious health problems such as heart attack, stroke, or limb amputation if not treated promptly.

Aetiology

Common causes include:

• Atherosclerosis: The most common cause of arterial occlusion, involving the build-up of plaque (a mixture of cholesterol, fat, and other substances) on the inner walls of the artery. Over time, the plaque hardens and narrows the artery, reducing blood flow.
• Thrombosis: A thrombus is a blood clot that forms within an artery. This can occur as a result of injury to the artery or due to conditions such as atrial fibrillation.
• Embolism: An embolism occurs when a clot or other material travels through the bloodstream and becomes lodged in an artery, blocking blood flow. Emboli may originate from the heart or other areas of the body and can consist of air bubbles, fat, or other materials.
• Trauma: Trauma to an artery can lead to occlusion by injuring the artery or causing a clot to form.
• Other causes: Medical conditions such as diabetes, hypertension, autoimmune diseases, and genetic factors can also increase the risk of arterial occlusion.

Pathophysiology

The pathophysiology of arterial occlusion can be divided into two phases: the acute phase and the chronic phase.

Acute phase: When an artery becomes occluded, blood flow to the tissue or organ it supplies is immediately reduced or cut off, leading to a lack of oxygen and nutrients. This can cause tissue death. For instance, an occlusion in a coronary artery may cause a heart attack, while an occlusion in a carotid artery can lead to a stroke.

Chronic phase: If the occlusion remains untreated, the body attempts to develop collateral circulation (new blood vessels) to bypass the blockage. However, these vessels are less efficient, potentially leading to chronic ischaemia, muscle atrophy, nerve damage, and skin changes in the affected area. Conditions such as chronic limb ischaemia, heart failure, or stroke may result from long-term arterial occlusion.

Risk Factors

Risk factors for arterial occlusion include:

• Age: The risk increases with age.
• Gender: Men are at higher risk compared to women.
• Family history: A family history of arterial occlusion increases the risk.
• Smoking: Smoking damages arterial walls and promotes plaque build-up.
• High blood pressure: Hypertension can damage arterial walls.
• High cholesterol: Elevated cholesterol levels contribute to plaque formation in arteries.
• Diabetes: Increases the risk of arterial occlusion.
• Obesity: Excess weight is a significant risk factor.
• Lack of physical activity: A sedentary lifestyle increases the risk.
• Poor diet: A diet high in saturated fats, trans fats, cholesterol, and salt increases the risk.

Signs and Symptoms

Common signs and symptoms of arterial occlusion include:

• Pain: Typically described as a dull ache, cramping, or sharp, stabbing pain, often worsened with exercise and relieved with rest.
• Numbness and tingling: Caused by nerve damage from reduced blood flow.
• Coldness: The affected area may feel cold to the touch due to reduced blood flow.
• Pale or blue skin: Resulting from reduced oxygen supply to the tissue.
• Weakness: Muscle weakness due to lack of blood flow.
• Loss of pulse: In severe cases, the pulse may be absent in the affected area.
• Paralysis or loss of movement: If the occlusion affects the carotid or cerebral artery, it can cause paralysis or loss of movement on one side of the body.
• Difficulty breathing: If the occlusion is in the pulmonary artery, it may cause breathing difficulties.

Investigations

Investigations for diagnosing arterial occlusion include:

• Ultrasound: Creates images of blood vessels and can detect blocked or narrowed arteries.
• Angiography: Uses X-rays and a special dye to visualise blood vessels, considered the gold standard for diagnosis.
• Magnetic Resonance Angiography (MRA) or Computed Tomography Angiography (CTA): Non-invasive imaging techniques to detect blocked or narrowed arteries.
• Doppler ultrasound: Uses sound waves to measure blood flow in the affected area.
• Ankle-brachial pressure index (ABI): Compares blood pressure in the ankle and arm to detect arterial occlusion in the legs.

Diagnosis

Physical examination: Identifies signs of arterial occlusion such as a weak or absent pulse, pale or blue skin, numbness, or tingling.

Management

The treatment for arterial occlusion depends on the location and severity of the blockage, as well as the overall health of the patient.

• Medications: Anticoagulants like aspirin, clopidogrel, or warfarin can prevent clot formation. Statins and blood pressure medications may also be prescribed.
• Thrombolysis: Medications like apixaban, rivaroxaban, and edoxaban are used to dissolve clots in patients who have had a heart attack or stroke.
• Surgery: Procedures such as angioplasty, stenting, or bypass surgery may be necessary to remove or bypass the blockage.
• Endovascular embolisation: Used to block the blood supply to specific areas of the body, typically in the case of aneurysms.
• Lifestyle changes: Quitting smoking, eating a healthy diet, and regular exercise can prevent further arterial occlusion.
• Monitoring: In some cases, stable occlusions may not require immediate treatment but regular monitoring to prevent worsening.

References

1. National Institute for Health and Care Excellence (NICE) (2024) Guidelines for the Management of Arterial Occlusion. Available at: https://www.nice.org.uk/guidance/ng196 (Accessed: 26 August 2024).
2. British Heart Foundation (2024) Understanding Arterial Occlusion. Available at: https://www.bhf.org.uk (Accessed: 26 August 2024).

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