What is a Clogged Artery?
A clogged artery (stenosis) is a blockage, either partial or complete, in the blood vessels that carry oxygenated blood to different areas of the body. This gradually or suddenly cuts off the blood supply to the target organ or tissue leading to cell injury (ischemia) or tissue death (infarct).
The main cause of the clogged artery or arteries is due to the development of atheromatous plaques (atherosclerosis). A thrombus or embolus are other common causes although the latter may not be detected as it is a blood clot that breaks away from a distant site and suddenly lodges in an artery.
Refer to Narrowing Artery Causes for more information on the causes of a clogged artery.
Symptoms of Clogged Artery
Narrowing of an artery may remain asymptomatic (silent) for long periods of time until the extent of the blockage significantly impairs oxygen and nutrient supply to the target area. A blocked artery, where there is a complete or almost complete occlusion, may result in a host of signs or symptoms that may vary depending on the site that is affected.
Refer to Blocked Artery Signs and Symptoms for a list of signs and symptoms related to a clogged artery supplying the heart, brain, lung, kidney and leg.
Two of the most common arterial blockages that also have the most serious complications are those of the carotid artery and coronary artery. Once these arteries are clogged even slightly, the process can rapidly progress until there is complete occlusion. This can lead to a stroke (cerebrovascular accident / CVA) when it involves the carotid artery or heart attack (myocardial infarction / MI) if the coronary artery is clogged.
Diagnosis of Clogged Arteries
Carotid Artery Blockage
Carotid artery disease may lead to transient ischemic attacks (TIA’s). These episodes usually precede a stroke (cerebrovascular accident) and are a sign that the brain is not receiving sufficient oxygen. Ischemia, which is tissue injury due to reduced oxygen supply, may occur in these attacks but there is usually no permanent damage. However, with a stroke, the ischemia progresses to an infarct which is a demarcated area where tissue dies in the brain.
- Doppler ultrasound / Duplex scanning
- Ultrasound scan of the neck area.
- Non-invasive method of identifying stenosis (narrowing) within the neck arteries – carotid artery as well as the vertebral artery.
- No risk to the patient.
- Anatomical resolution is limited but nevertheless effective in skilled hands. Transcranial doppler can even image intracerebral blood flow.
- Computer Topography angiography (CTA)
- Preferred method of diagnosing and assessing extent of carotid artery disease.
- Injection of radio-opaque contrast (dye) without catheter insertion as is the case with cerebral angiogram (below).
- Three-dimensional perspective by using multiple sectional x-ray images.
- Cheaper, faster and more widely available facilities for CTA than MRA.
- Magnetic resonance angiography (MRA)
- Less invasive that conventional angiogram.
- Not suitable for patients with metal implants, pacemakers or if morbidly obese.
- No radiation exposure.
- Non-iodinated contrast (dye) is used.
- High quality 3D images.
- Cerebral angiogram (Conventional angiogram)
- Intra-arterial injection of radio-opaque contrast (dye) via a catheter to highlight the artery, any narrowing (stenosis) and blood flow upon x-ray imaging.
- Invasive procedure and risk of complications with intravascular (higher in intra-arterial than intravenous) injection is significantly high.
- Less frequently done if CT angiography is available due to an increased risk of stroke after a conventional angiogram.
Coronary Artery Blockage
Coronary artery disease may lead to angina. Episodes of angina may precede a heart attack (myocardial infarction) and are an indication of the heart muscle not receiving sufficient oxygen. Chest pain is the most commonly report symptom and early detection is crucial to avoiding a heart attack. The investigations below are also discussed in the article on Chest Pain Tests.
A CTA (computerized topography angiography), MRA (magnetic resonance angiography) and conventional angiogram can be used to map the coronary artery and assess any narrowing or occlusion. This is similar to the procedures mentioned above for a carotid artery assessment.
In addition, the following tests may also be useful in assessing the extent of any damage due to coronary artery blockage.
- Electrocardiogram (ECG) measures electrical activity of the heart muscle.
- Echocardiogram utilizes ultrasound to create images of the heart and assess heart muscle movement.
- Stress tests are conducted by using an ECG or echocardiogram while the patient exercises (treadmill or stationary bike). This assess the ability of the heart to cope with increased physical activity.
The above tests (ECG and echocardiogram) measures the effect of the reduced blood flow due to a clogged coronary artery. However, it will not assess the extent of the actual blockage within the artery.
A nuclear stress test uses radioactive material injected into the bloodstream to assess blood distribution to the heart muscle during exercise. This may be useful in assessing the extent of a coronary artery blockage.