Atherosclerosis (plaque deposition inside the arteries)

 

• Global

Atherosclerosis is the number one cause of vascular diseases and deaths worldwide.[5,6]

 

As per the Healthcare Cost and Utilization Project (HCUP), in 2011, coronary atherosclerosis was among the top 10 most expensive conditions seen in hospitalized patients who were kept under observation in the US, with aggregate inpatient hospital cost of $10.4 billion.[7]

• India

Cardiovascular diseases have been a leading cause of morbidity and mortality in India. Its prevalence varies from 1−2% in rural populations and from 2−4% in urban populations.[8]

 

Causes[9,10,11]

 

The exact cause of atherosclerosis is not known. However, studies show that atherosclerosis is a slow and complex disease that may begin in early childhood. Atherosclerosis may start with damage or injury to the inner layer of an artery, which may be caused by smoking, high blood pressure, high amounts of certain fats and cholesterol in the blood, high amounts of sugar in the blood due to insulin resistance or diabetes, etc.

• Plaque begins to deposit on the inner wall of the injured or damaged arteries. Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. Over time plaque hardens, narrowing the arteries. Narrowing of the arteries limits the flow of oxygen-rich blood to the rest of the body. This as a result reduces the functioning of the organs and tissues connected to the blocked arteries.

 

 

Although the exact cause is unknown, there are several risk factors that can determine the chances of developing atherosclerosis. Apart from age and family history, there are many risk factors which can be controlled by implementing proper lifestyle changes.

 

 

• High blood pressure: Blood pressure is considered high if it stays at or above 140/90 mmHg over time. When the blood inside the arteries is pumped at an excessive pressure, the internal lining of the arteries’ walls get damaged, contributing to the development of atherosclerosis.

• High cholesterol: Cholesterol has a range of essential functions in the body and contributes to cell structure and hormone production. There are two types of cholesterol: high-density lipoprotein (HDL), sometimes called the good cholesterol and low-density lipoprotein, called the bad cholesterol. Low-density lipoprotein (LDL) cholesterol particles are subclassified into two types—small dense (type-B) and large fluffy (type-A). Excess of LDL cholesterol in the blood can damage the arteries, thereby leading to the deposition of plaque on their walls. Therefore, excess of LDL, especially the small dense subfractions can contribute to atherosclerosis.

• Smoking: In addition to all the diseases smoking can cause, atherosclerosis is another one. Smoking can tighten blood vessels, raise cholesterol levels, raise blood pressure, and damage the artery walls. Subsequently, plaque begins depositing in the damaged artery walls, leading to the narrowing of the arteries.

• Diabetes: In a diabetic individual, the body's blood sugar level is usually very high because the body does not make enough insulin or does not use its insulin properly. This can damage the walls of the arteries, increasing the risk of atherosclerosis.

• Unhealthy diet: Foods high in saturated and trans fats, cholesterol, sodium (salt), and sugar can worsen other atherosclerosis risk factors.

• Overweight/Obesity: Being overweight or obese can indirectly predispose a person to atherosclerosis by increasing the chance of developing associated risk factors, such as type 2 diabetes mellitus, high blood pressure, and high cholesterol.

• Lack of exercise: Lack of physical activity can worsen other risk factors for atherosclerosis, such as high blood pressure, unhealthy blood cholesterol levels, and diabetes. Lack of exercise can also make a person overweight and obese, thereby increasing the risk of developing atherosclerosis. 

• Family history: An individual whose father or brother develops the disease before the age of 55, or whose mother or sister develops the condition before the age of 65 is at a higher risk than the rest of the population. Therefore, a person's risk of developing atherosclerosis can be as much as double if they have a first degree relative with the condition.

• Age: As one gets older, the risk for atherosclerosis increases. Genetic or lifestyle factors cause plaque to build up in the arteries as one grows older. By the time one becomes middle-aged or older, enough plaque gets accumulated to cause signs or symptoms. In men, the risk increases after the age of 45, whereas in women the risk increases after 55.[9,10,11]

Atherosclerosis itself has no obvious symptoms, it is asymptomatic. Signs and symptoms only occur when an artery becomes so narrowed or clogged that it becomes incapable of supplying enough blood to the organs or tissues.

 

Symptoms depend upon the arteries which have been affected by atherosclerosis. For example:

• Atherosclerosis in heart arteries: Chest pain or pressure (angina).
• Atherosclerosis in the arteries of the brain: Numbness or weakness in the arms or legs, difficulty in speaking or slurred speech, or drooping muscles in the face.
• Atherosclerosis in the arteries of arms and legs: Leg pain when walking (intermittent claudication).
• Atherosclerosis in the arteries leading to kidneys: One may develop high blood pressure or kidney failure.
• Atherosclerosis in the arteries leading to genitals: One may experience difficulties in having sex. Sometimes, atherosclerosis can cause erectile dysfunction in men. In women, high blood pressure can reduce blood flow to the vagina, making sex less pleasurable.

In most cases, atherosclerosis is detected in patients only when they suffer from cardiovascular disorders such as stroke or heart attack.

 

 

Diagnosis of atherosclerosis is based on the medical and family history, a physical exam, and laboratory test results.

 

Physical Exam

During the physical exam, the doctor will check the pulses to feel whether they are weak or absent. A weak or absent pulse can be a sign of a blocked artery.

 

The doctor will also listen to the arteries for an abnormal whooshing sound called bruits. The doctor can hear bruits on placing a stethoscope over an affected artery. A bruit may indicate poor blood flow due to plaque build-up. 

 

Diagnostic Tests

Depending on the symptoms and results of the physical exam, the doctor may recommend one or more of the following tests to diagnose atherosclerosis. These tests can help the doctor know the extent of the disease and plan the best treatment accordingly.

• Blood tests: Blood tests such as lipid profile test and blood sugar test can detect increased levels of certain fats, cholesterol, sugar, and proteins that may increase the risk of atherosclerosis. Abnormal levels may indicate risk for atherosclerosis. One should not eat or drink anything except water for 9–12 hours before the blood test.

• Electrocardiogram (ECG): A resting ECG is recommended to the patients who show any sign of artery blockage during the physical exam. An ECG records the strength and timing of electrical signals as they pass through the heart. An ECG can reveal evidence of previous or current heart attack. If the signs and symptoms occur mostly during exercise, the doctor may ask the patient to walk on a treadmill or ride a stationary bike during an ECG.

• Chest X-ray: A chest X-ray can capture the pictures of organs and structures inside the chest such as the heart, lungs, and blood vessels.

• Echocardiography: It is done to assess the pumping function of the heart (ejection fraction) and regional wall motion abnormalities. These abnormalities signify underlying blockages in heart arteries.

• Color Doppler: It is used to study the lower limb, carotid, or renal arteries depending on the symptoms of the patient.

• Ankle/brachial index: In this test, the doctor compares the blood pressure in the ankle with the blood pressure in the arm to observe how well the blood is flowing. An abnormal difference in the blood pressure can indicate peripheral artery disease caused by atherosclerosis.

• Computed tomography (CT) scan: A computed tomography (CT) scan can reveal the hardening and narrowing of large arteries. A cardiac CT scan can also show if calcium has built-up in the walls of the coronary arteries.

• Stress testing: A stress test is used to gather information on how well the heart works during physical activity. It usually involves walking on the treadmill or riding a stationary bike. For a person who cannot exercise, a medicine may be given to make the heart work harder and beat faster. The heart’s rhythm and blood pressure are monitored during the test. A stress test can show possible signs and symptoms of coronary heart disease including:

1. Abnormal changes in the heart rate or blood pressure

2. Shortness of breath or chest pain

3. Abnormal changes in the heart rhythm or the heart's electrical activity.

 

In some tests, pictures of the heart while working out and at rest are taken and compared. These images can reveal how well the blood is flowing to the various parts of your heart and how well the heart pumps blood when it beats.

 

Some of the commonly available stress tests include stress echocardiography (stress echo), dobutamine stress echocardiogram (DSE), stress thallium/single photon emission computed tomography (SPECT), and adenosine/dobutamine SPECT.    

• Angiography: In this test, a liquid dye is injected into the arteries through a thin tube (catheter), usually inserted through the leg or wrist artery. As the dye fills the artery, the arteries become visible on X-rays, showing areas of blockage.

• Computed Tomography Angiography: In this procedure, an iodine-rich contrast material (dye) is usually injected through a small catheter placed in an arm’s vein. A computerized tomography (CT) scan is then performed while the contrast flows through the blood vessels to the various organs of the body. After scanning, the image is processed using a special computer and software and reviewed in different planes and projections.

• Other Tests: Other tests such as magnetic resonance imaging (MRI) and positron emission tomography (PET) are being studied to see if they can give a better view of plaque build-up in the arteries.

 

 

Lifestyle changes, such as eating a healthy diet and exercising, are the most appropriate treatments for atherosclerosis. Medications are routinely prescribed for treatment and in severe cases, surgical procedures may be recommended.

 

The goals of treatment include:

• Relieving symptoms
• Reducing risk factors to prevent or slow the progression
• Preventing atherosclerosis-related diseases in other organs
• Widening or bypassing plaque-clogged arteries.

Medicines: Treatment with drugs reduces the blood pressure, corrects unhealthy cholesterol levels, and lowers the risk of complications. 

 

Some of the common choices are:

1. Cholesterol-lowering medications/statins: Lowering the LDL cholesterol can slow or stop the build-up of fatty deposits in the arteries. Statins and fibrates are usually prescribed. In addition to lowering cholesterol, statins help in stabilizing the inner lining of the heart arteries and prevent atherosclerosis.

2. Antiplatelet medications: Antiplatelet medications, such as aspirin, are prescribed to reduce the likelihood of platelets clumping in narrowed arteries and cause further blockage.

3. Beta-blocker medications: Beta-blockers lower the heart rate and blood pressure, thereby reducing the pressure on the heart. Beta-blockers often relieve the symptoms of chest pain. Beta-blockers reduce the risk of heart attacks and some heart rhythm problems.

4. Angiotensin-converting enzyme (ACE) inhibitors: They help slow down the progression of atherosclerosis by lowering blood pressure and producing other beneficial effects on the heart arteries. ACE inhibitors also reduce the risk of recurrent heart attacks.

5. Calcium channel blockers: They lower blood pressure and sometimes used for treating angina.

Statins:

• Atorvastatin
• Fluvastatin
• Lovastatin
• Pravastatin
• Rosuvastatin
• Simvastatin
• Pitavastatin.
•  

Blood thinner:

• Aspirin / Acetylsalicylic acid
• Clopidogrel.

 

Other drugs:

• Ivabradine
• Nicorandil
• Ranolazine
• Trimetazidine.

 

Individuals with severe atherosclerosis may require a medical or surgical procedure. One of the following procedures may be indicated in patients with severe atherosclerosis:

• Angioplasty and stent placement: In this procedure, a long, thin tube (catheter) is inserted into the blocked or narrowed part of the artery. A second catheter with a deflated balloon on its tip is then passed through the catheter to the narrowed area. After which the balloon is inflated, compressing the built-up deposits against the artery walls. A medicated stent (mesh tube) is usually deployed in the artery to keep the artery open.

• Coronary artery bypass grafting (CABG): A healthy blood vessel (arteries or veins) from another part of the body is used to bypass or go around the narrowed coronary arteries. CABG helps improve blood flow to the heart, relieve chest pain, and possibly prevent a heart attack.

• Carotid Endarterectomy: In this procedure, the plaque build-up from the carotid arteries in the neck is removed surgically. This restores blood flow to the brain, which can help prevent a stroke.

 

 

Certain lifestyle measures can be implemented to manage the risk factors for atherosclerosis. Achieving and maintaining a healthy body weight reduces the risk of developing atherosclerosis. Consuming an appropriate amount of calories is fundamental to control body weight.

• An individual with either type 1 or type 2 diabetes mellitus should carefully follow the advice of the doctor or dietitian, and effectively control his blood glucose levels. Doing so can reduce the risk of developing atherosclerosis to a large extent. 

• Giving up smoking is considered the single most important thing a person can do for the health of his/her heart.

• Maintaining healthy cholesterol levels through balanced diet reduces the risk of atherosclerosis. Switching out fatty foods for fruits, vegetables, and whole grain cereal can help an individual lower his/her cholesterol levels.

• Being physically active and exercising regularly can help maintain healthy arteries by keeping the blood pressure in control.

 

 

Prevention is generally by lifestyle changes such as eating a healthy diet, exercising regularly, not smoking, and maintaining a normal weight.

 

1. Eating a healthy diet: A healthy diet is an important factor in preventing atherosclerosis. A heart-healthy diet includes fruits and vegetables, whole grains, lean meats, poultry without skin, seafood, and fat-free or low-fat milk and dairy products. Using monounsaturated fats, such as olive oil, and reducing or eliminating sugar and sugar substitutes also helps. Evidence suggests that Mediterranean diet may also improve cardiovascular results.

 

Every cooking oil has its own unique chemical composition. Therefore, it is advised to rotate the cooking oil every 2–3 months. Rotation of oil reduces the risk of cardiovascular diseases, diabetes, and obesity which are linked to the over intake of edible oils.

Oily fish like salmon, mackerel, sardines, trout, herring, etc. are preferred as they contain long chain omega-3 fatty acid which helps in preventing heart disease. Steamed, baked, and grilled fishes are a healthier choice as compared to fried fish.[12,13]

 

2. Consumption of excess salt causes the body to keep or retain too much water and increases the blood pressure. As per the American Heart Association (AHA), one should not have more than 2,300 mg of sodium per day and considers less than 1,500 mg a day as ideal.[14,15]

3. Exercise: Regular exercise improves blood circulation and functionality of the blood vessels. Exercise lowers many atherosclerosis risk factors such as low-density lipoprotein (LDL) cholesterol, high blood pressure, and excess weight. Physical exercise lowers the risk of developing diabetes and raises high-density lipoprotein cholesterol (HDL), which helps in preventing atherosclerosis. In addition, regular exercise can condition the muscles to use oxygen more efficiently. It is recommended to perform at least 150 minutes of moderate intensity or 75 minutes of vigorous-intensity aerobic physical activities every week or an equivalent combination thereof.

 

4. Maintaining a healthy weight: Maintaining a healthy desirable weight is not only important for overall health, it can also lower the risk of atherosclerosis. Losing weight reduces total and LDL cholesterol (bad cholesterol), boosts HDL cholesterol (good cholesterol), and reduces triglycerides. It also helps in reducing blood pressure. Eating the right food and exercising regularly are two key components to maintain a desirable body weight. Internationally, a BMI of 25.0–29.0 kg/m2 is considered overweight, 30–34.9 kg/m2 obese, and ≥35 kg/m2 as morbidly obese. However, the BMI categories for Asian Indians have been revised based on consensus guidelines. The revised guidelines categorize overweight as a BMI of 23.0–24.9 and obesity as a BMI ≥25.[16]

 

5. Stop smoking: Smoking tobacco can tighten and damage the blood vessels, increasing the risk of atherosclerosis. Giving up smoking is one of the best ways to stop the progression of atherosclerosis and reduce one’s risk of complications. One should also try to avoid passive smoking. There are approved effective treatments to help one stop smoking including behavioral therapies and medications. A variety of medications are available to help one quit smoking, e.g., bupropion and varenicline.

 

6. Manage consumption of alcohol: Excessive consumption of alcohol is known to increase blood pressure and raise the levels of some fats in the blood. For individuals who consume alcohol, it is advised to do so in moderation. The American Heart Association (AHA) recommends limiting alcohol to no more than two standard drinks per day for men and one standard drink per day for women. One standard drink (alcoholic drink-equivalent) is defined as 14 millimeter (mL) of pure alcohol.[17]

 

 

7. Managing stress: Research shows that the most commonly reported "trigger" for a heart attack is an emotionally upsetting event. The ways some people cope with stress is by drinking, smoking, or overeating, neither of which is healthy. Learning how to manage stress and how to cope with problems improves one’s emotional and physical health. A healthy mind will always have a favorable effect on your cardiovascular health.[18]

 

Atherosclerosis can affect any artery in the body, including arteries in the heart, brain, arms, legs, pelvis, and kidneys. The complications depend upon the arteries affected by atherosclerosis.

• Heart Attack

When atherosclerosis narrows the arteries close to the heart, the person may develop coronary artery disease, which can cause chest pain (angina), heart attack, or heart failure.

• Stroke

When atherosclerosis narrows the arteries supplying blood to the brain tissue, one may suffer from stroke or transient ischemic attack (TIA).

• Peripheral Artery Disease

When atherosclerosis narrows the arteries in the arms or legs, the person may develop circulation problems in the arms and legs called peripheral artery disease. This can cause pain in the limbs while walking (claudication) and can make them less sensitive to heat and cold, increasing the risk of burns or frostbite. In rare cases, poor circulation in the arms or legs can cause tissue death (gangrene).

• Aneurysms

An aneurysm is a bulge in the wall of the artery. Atherosclerosis can also cause aneurysms, a serious complication that can occur anywhere in the body. Most people with aneurysms have no symptoms. Pain and throbbing in the area of an aneurysm may occur which is a medical emergency.

If an aneurysm bursts, the person may face life-threatening internal bleeding. Although this is usually a sudden, catastrophic event, a slow leak is possible. If a blood clot within an aneurysm dislodges, it may lead to blockage of an artery at some distant point.

• Kidney Problems

Plaque occurrence and accumulation in the kidney arteries lead to decreased kidney blood flow and chronic kidney disease, which, like all other areas, are typically asymptomatic until late stages.

• Chronic Kidney Disease

The renal arteries supply oxygen-rich blood to the kidneys. When atherosclerosis narrows the renal arteries, one may develop chronic kidney disease. In the early stage, it has no signs or symptoms. However, as the disease progresses, it can cause tiredness, loss of appetite, nausea, swelling in the hands or feet, itchiness or numbness, and trouble concentrating.

 

 

• Arteriosclerosis is derived from the Greek words artēria, meaning artery, and sklerosis, meaning “hardening”.
• Atherosclerosis is a slow, progressive disease that may start in one’s childhood.
• Atherosclerosis commonly affects the artery at the origins of tributaries, bifurcations, and curvatures.[19]
• Smoking increases the chance of developing atherosclerosis.
• Plaque are made up of fat, cholesterol, calcium, and other substances found in the blood.
• Atherosclerosis is usually the first stage of coronary heart disease.
• Atherosclerosis may remain undiagnosed until more serious problems such as heart attack or stroke occur.
• Eating a healthy diet and exercising regularly are the most effective ways to prevent or slow the progress of atherosclerosis.
• Ischemic heart disease which is a consequence of atherosclerosis is the leading cause of deaths worldwide. 

 References 

 

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