Atherosclerosis

Atherosclerosis is a subtype of arteriosclerosis. Arteriosclerosis is a general term for the hardening of arteries and, in its progression, the walls of arteries become thick and stiff, sometimes preventing the flow of blood to organs and tissues. Atherosclerosis is a disease in which fatty substances, cholesterol, cellular waste products, calcium and some other substances accumulate in the inner lining (intima) of artery. Collectively, the accumulated substances are referred to as plaque. Over time, plaque continues to accumulate, hardens and eventually narrows the lumen of arteries. Ischaemia or reduced blood flow can lead to serious problems, depending on the specific artery affected.


The typical progression of atherosclerosis begins when tears or fatty streaks in the inner lining of blood vessels attract monocytes (type of white blood cell) and stimulate the cellular immune response. Advanced lesions (any abnormality of tissue in any area of the body) develop when cholesterol, calcium crystals, and cellular debris builds up within the inner lining (intima). The increase in size of the affected intima narrows the lumen of the vessel. Clotting factors (substances produced in response to injury) and platelets (smallest type of blood cell) are activated by contact with the lesions. Thrombi (blood clots) may build on lesions or move downstream, potentially blocking the artery.
A condition or disease masy result due to the advanced progression of atherosclerosis in particular areas of the body. For instance:

• Peripheral arterial disease develops when arteries supplying the limbs are affected, consequently circulation problems in the arms and legs may occur.
  
• Coronary artery disease develops when arteries supplying the heart are affected and there’s a possibility of experiencing chest pain (angina) or a heart attack (myocardial infarction).
  
• Transient ischemic attack or stroke arises when arteries supplying blood to the brain are affected.
  

Also, atherosclerosis can possibly also lead to a bulge in the wall of an artery, which may be referred to as an aneurysm.

Signs & Symptoms
Atherosclerosis usually doesn’t show signs or symptoms until it progresses to a point where an artery is partially or fully blocked. In most cases, it takes a medical emergency to give an indication of progressing atherosclerosis. Otherwise, the signs and symptoms experienced depend on which arteries are severely affected. For instance:

• Obstruction of arteries supplying the brain, i.e. carotid arteries in the neck, may cause symptoms of a stroke, such as dizziness, sudden numbness or weakness.


• Obstruction of arteries to the heart (coronary arteries) may cause symptoms of a heart attack, e.g. angina pectoris (chest pain which is normally relieved after a few minutes of rest, in contrast to a heart attack in which the pain is more intense and is not relieved by rest.)


• Obstruction of the arteries supplying the arms and legs may cause symptoms of peripheral arterial disease, such as leg pain when walking, numbness or sometimes serious infections.

Men may go through sexual dysfunction because of hardening of the arteries.

Causes and Associated Risks

Although the exact cause of atherosclerosis is unknown, it is suspected to begin with damage to the inner layer of an artery. The damage may be as a result of high blood pressure, high cholesterol, an irritant such as nicotine or certain diseases like diabetes. Thus, the risk factors of atherosclerosis include high blood pressure, high cholesterol, diabetes, obesity, smoking and having a family history of an aneurysm or early heart disease.

Screening and Diagnosis

Diagnosis is normally based on three (3) things:

• your medical and family histories


• risk factors


• results of a physical exam and dianostic tests.

During a physical exam, signs of narrowed, enlarged or hardened arteries may be found. These signs may include:

• Whooshing sounds over arteries, heard with a stethoscope.


• Evidence of poor wound healing in the area where blood flow is being restricted.


• A weak or absent pulse below the narrowed area of the artery.


• Decreased blood pressure in an affected limb.


• Signs of a pulsating bulge (aneurysm) in the abdomen or behind the knee.

Depending or the results of a physical exam, one or more diagnostic tests may be performed, including:

1. Angiogram - a special dye may be injected into the arteries before a chest x-ray is done to give an indication of how blood is flowing through the vessels and whether there are any blockages.

2. Ankle-Brachial Index - used to compare the blood pressure in the ankle to that in the arm. Any abnormal difference may indicate peripheral vascular disease.

3. Blood tests - increased levels of cholesterol, blood sugar and other substances that may increase the risks of atherosclerosis may be detected.

4. Doppler Ultrasound - a special ultrasound device is used to measure blood pressure at various points of the arms and legs to determine the degree of any blockages, as well asthe speed of blood flow in the arteries.

5. Electrocardiogram (ECG/EKG) – records electrical signals as they move through the heart. It can give an indication of how nerve impulses pass through the heart and whether a myocardial infarction is progressing or has occurred recently.

6. Other imaging tests – can also be used to study the arteries, such as an ultrasound, computerized tomography (CT) scan or a magnetic resonance angiogram (MRA).

Treatment
The main treatment for atherosclerosis is lifestyle changes. Medicines and medical procedures may also be required. Treatment seeks to: relieve any symptoms; reduce risk factors in an effort to slow, stop or reverse the build-up of plaque; lower the risk of blood clots forming; widen or bypass clogged arteries; prevent diseases related to atherosclerosis.

Lifestyle changes can promote healthier arteries. Sometimes, these changes may be the only treatment necessary. Otherwise, medication or surgical procedures may be recommended as well.

Medication

• Anticoagulants – such as heparin, can aid in blood thinning to prevent clots from forming.
  
• Anti-platelet medications – such as aspirin, can lessen the likelihood of platelets clumping in narrowed arteries.
  
• Blood pressure medications – can help slow the progression of atherosclerosis.
  
• Cholesterol medications – (see post on high cholesterol)
• Other medications – can be used to control specific risk factors or treat symptoms of atherosclerosis.
  

Procedures
In severe cases, any one of the following procedures may be necessary:

1. Angioplasty – a long, thin tube (catheter) is inserted into the narrowed part of the artery. Then a wire with a deflated balloon is passed through the catheter to the narrowed area. The balloon is inflated, compressing the deposits against the artery walls in the hopes of reopening the artery, if blocked.

2. Bypass surgery – a graft bypass using a vessel from another part of the body or a tube made of synthetic fabric is created to give rise to an alternate path for blood to flow.

3. Endarterectomy – fatty deposits are surgically removed from the walls of a narrowed artery.

4. Thrombolytic therapy - a clot-dissolving drug may be inserted into the artery to break up a blood clot blocking the artery.