Atherosclerosis

Overview

Atherosclerosis is the accumulation of plaque (fatty deposits) in your arteries. The blood artery wall thickens as plaque accumulates. This narrows the artery's lumen, limiting blood flow. This reduces the quantity of oxygen and other nutrients that reach the body.

 

What is Atherosclerosis?

Atherosclerosis is a chronic inflammatory condition of the arteries that accounts for approximately 50% of all fatalities in Westernized societies. It is primarily a lipid-driven process that is initiated by the accumulation of low-density lipoprotein and remnant lipoprotein particles and an active inflammatory process in focal areas of arteries, particularly at regions of disturbed non-laminar flow at branch points in the arteries, and is regarded as a primary cause of atherosclerotic cardiovascular disease (ASCVD) that results in heart attacks, stroke, and peripheral arterial disease.

Because atherosclerosis is primarily asymptomatic, determining the incidence properly is challenging. Atherosclerosis is often regarded as the leading cause of cardiovascular disease. Ischemic heart disease (IHD) and ischemic stroke are the most common forms of atherosclerotic cardiovascular disease. IHD and stroke are the world's primary and fifth leading causes of mortality.

Every year, over 610,000 individuals in the United States die as a result of heart disease. That equates to one out of every four deaths. Coronary heart disease is the leading cause of mortality in the Western world, claiming the lives of about 370,000 individuals each year. Every year, around 735,000 Americans experience a heart attack. 525,000 had an initial attack, while 210,000 have recurring attacks.

It has been claimed that plaque rupture causes 75% of acute myocardial infarctions, with males over 45 years having the highest incidence, while women have a higher prevalence after the age of 50. This higher frequency of atherosclerosis in males is due to the preventive effect of female sex hormones, which is lost after menopause.

Stroke is the fifth highest cause of mortality and the top cause of significant long-term disability in people in the United States. Every year, almost 795,000 people in the United States suffer from stroke, resulting in around 140,323 fatalities. The most common kind of stroke, ischemic stroke, is caused by ASCVD.

Many epidemiologic studies in North America and Europe have identified various risk factors for the development and progression of atherosclerosis. They may contribute to atherosclerosis through their effects on low-density lipoprotein (LDL) particles and inflammation.

 

What are causes of Atherosclerosis?

The cause of ASCVD is multifaceted. Hypercholesterolemia (LDL-cholesterol), hypertension, diabetes mellitus, cigarette smoking, age (male older than 45 years and female older than 55 years), male gender, and a strong family history (male relative younger than 55 years and female relative younger than 65 years) are the most common risk factors. Sedentism, obesity, saturated and trans-fatty acid diets, and specific genetic variations all add to risk. While a low amount of high-density lipoprotein (HDL) cholesterol is considered a risk factor, pharmaceutical treatment to increase HDL cholesterol has had unfavorable outcomes, raising questions regarding HDL's function in ASCVD.

 

How Atherosclerosis starts and how it progresses? 

Atherosclerosis is primarily caused by the continuous process of arterial wall lesions caused by lipid retention by trapping in the intima by a matrix such as proteoglycans, resulting in a modification that aggravates chronic inflammation at vulnerable sites in the arteries and plays an important role at all stages of atherogenic progression. This process begins with nascent fatty streaks in the artery intima, progresses to fibrous plaques, and culminates in complicated atherosclerotic lesions that are prone to rupture. Furthermore, stenosis caused by atheroma inward expansion might result in blockage of arteries such as the coronaries. Exuberant collateral circulation, on the other hand, can alleviate clinical illness.

The systemic alterations found in atherosclerosis are quite similar in the aorta, coronary, and carotid arteries. The continuous process of atherosclerosis is commonly understood as a long series of histologic changes or a number of distinct kinds of lesions that can be seen with the naked eye.

 

Atherosclerosis Symptoms

Because the arteries enlarge at all plaque locations, there is no effect on blood flow and atherosclerosis remains asymptomatic for decades. Even most plaque ruptures do not cause symptoms until substantial constriction or closure of an artery occurs as a result of clots. Signs and symptoms appear only when a substantial constriction or closure obstructs blood flow to several organs sufficiently to cause symptoms. Most individuals are unaware they have the condition until they encounter other cardiovascular diseases such as a stroke or heart attack. However, these symptoms differ depending on which artery or organ is afflicted.

Atherosclerosis-related abnormalities emerge in infancy. Children aged 6 to 10 have fibrous and gelatinous lesions in their coronary arteries. Fatty streaks have been found in the coronary arteries of children aged 11 to 15, although they first develop in the aorta at a far younger age.

Clinically, symptomatic atherosclerosis is often linked with males in their 40s and women in their 50s to 60s, owing to decades of artery expansion. Subclinically, the condition appears in childhood and is seldom present at birth. At puberty, noticeable indications might emerge. Though symptoms are uncommon in children, early screening for cardiovascular disease may benefit both the kid and his or her family. While coronary artery disease affects males more than women, atherosclerosis of the cerebral arteries and strokes affect both sexes equally.

A significant constriction of the coronary arteries, which are responsible for supplying oxygenated blood to the heart, can cause symptoms such as angina-related chest pain and shortness of breath, perspiration, nausea, dizziness or light-headedness, dyspnea, or palpitations. Ischemia can also cause abnormal cardiac rhythms known as arrhythmias (the heart beating too slowly or too fast).

The carotid arteries transport blood to the brain and neck. A significant narrowing of the carotid arteries can cause symptoms such as weakness, inability to think clearly, trouble speaking, dizziness, difficulty walking or standing up straight, blurred vision, numbness of the face, limbs, and legs, severe headache, and loss of consciousness. These symptoms are also associated with stroke (death of brain cells). Stroke is caused by a significant constriction or closure of the arteries leading to the brain; a lack of sufficient blood flow causes the cells of the afflicted region to die.

Peripheral arteries, which provide blood to the legs, arms, and pelvis, are also significantly narrowed as a result of plaque rupture and clots. Numbness and discomfort in the arms or legs are symptoms of the narrowing. The renal arteries, which feed blood to the kidneys, are another important site for plaque development. Plaque formation and buildup result in reduced renal blood flow and chronic kidney disease, both of which are often asymptomatic until late stages.

 

Diagnosis

Measuring the lipid profile (LDL-cholesterol), plasma glucose, and high-sensitivity C-reactive protein (hsCRP) is appropriate in assessing ASCVD risk factors. The elderly should have an abdominal ultrasound to test for an aneurysm, especially if they have additional ASCVD risk factors. A Doppler instrument is used to get the ankle-brachial index (normal 1.0 to 1.40) in screening for peripheral artery disease (PAD) and is a highly helpful, cost-effective diagnostic to rule out PAD. 

It should be underlined that PAD is a risk factor for ASCVD in other beds (coronary artery disease [CAD], cerebrovascular disease, among others). If a patient has a carotid bruit, sonography of the carotids should be performed to rule out stenosis. If warranted, an electrocardiogram (ECG) may be beneficial, such as a stress ECG. A good test to confirm ASCVD is the calcium score using electron beam computed tomography. It must be interpreted based on age. It determines plaque load.

Angiography is the principal tool for visualizing atherosclerotic lesions in the coronary circulation and provides an accurate measurement of the coronary silhouette. It is, however, an invasive operation that should only be conducted in high-risk individuals or those who have symptoms, and it is not a screening test.

Computed tomography (CT) angiography is emerging as a potential method for the noninvasive evaluation of ASCVD. Furthermore, CT angiography can be utilized to detect low-attenuated plaques and predict future acute coronary events. Aside from CT angiography, emerging imaging methods such as cardiovascular magnetic resonance imaging (cardiac MRI) may be beneficial in some individuals. However, given the rising expense of healthcare, expenditure must be matched with necessity.

 

Management

Treatment of risk factors such as increased LDL-C, blood pressure (BP), and diabetes, among others, is the best way to control ASCVD. In addition, all patients should be encouraged to exercise for 90 to 150 minutes per day and eat a healthy diet low in saturated (red and processed meat, organ meats, and the like) and trans fats (baked goods), with a salt intake of less than 5 grams per day and an abundance of fiber, monounsaturated fats, fatty fish, fruits, and vegetables. Tobacco users should be urged to quit and sent to a smoking cessation program.

Statins (inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase) are the backbone for lowering LDL cholesterol and reducing cardiovascular events and death. Angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), diuretics, beta-blockers, calcium channel blockers (CCBs), and vasodilators are all needed to manage blood pressure. It should be underlined to the patient that appropriate blood pressure control avoids stroke, and that an ideal blood pressure is less than 130/85. Diabetes can be managed with a variety of medications in addition to diet and exercise. In primary prevention, the objective is to keep glycated hemoglobin (HbA1c) below 7%, blood pressure below 130/85, and LDL-cholesterol below 100 mg/dl.

Revascularization techniques such as angioplasties and bypass, among others, are indicated for clinical ASCVD. Thrombolysis is also a treatment option for CVA and acute limb ischemia caused by a thrombus/embolus.

 

Surgery

If you have severe atherosclerosis, your doctor may suggest surgery to manage your condition. Atherosclerosis procedures include:

• Percutaneous coronary intervention (PCI or angioplasty with stent) is a procedure in which a balloon (stent) is put into a constricted conduit and inflated to enlarge it.
• Endarterectomy surgery on the carotid artery to eliminate plaque.
• Coronary artery bypass surgery Blood is redirected around the narrowed or blocked artery.

 

Living with atherosclerosis

It is reasonable to be concerned or terrified after being diagnosed with atherosclerosis. Find a family member, friend, doctor, mental health worker, or support group to whom you may turn for emotional help. Talking about your difficulties and feelings might be a crucial component of your rehabilitation process.

Cardiac rehabilitation is a specific program of exercise, education, and counseling designed to assist you in recovering from heart disease and lowering your risk of future heart issues. Consult your doctor for information on finding a program in your region, or contact your local public health agency or hospital.

 

Prevention

If recognized risk factors are avoided, up to 90% of cardiovascular disease may be avoidable. The initial step in medical care of atherosclerosis is to modify risk factors, such as smoking cessation and dietary limitations. In general, prevention involves eating a good diet, exercising, avoiding smoking, and keeping a normal weight.

 

Diet

Dietary changes may aid in the prevention of atherosclerosis. According to preliminary research, a dairy-rich diet has no effect on or reduces the risk of cardiovascular disease.

A fruit and vegetable-rich diet lowers the risk of cardiovascular disease and mortality. The Mediterranean diet may enhance cardiovascular outcomes, according to evidence. There is additional evidence that a Mediterranean diet may be more effective than a low-fat diet in changing cardiovascular risk factors over time (e.g., lower cholesterol level and blood pressure).

 

Exercise

A regulated exercise regimen fights atherosclerosis by increasing circulation and vascular functioning. Exercise is also used to help obese individuals lose weight, improve blood pressure, and lower cholesterol. Often, lifestyle changes are paired with pharmacological therapy. Statins, for example, can help decrease cholesterol. Aspirin and other antiplatelet drugs assist to avoid clots, while a number of antihypertensive medications are commonly used to manage blood pressure. If the combined efforts of risk factor management and drug therapy fail to control symptoms or combat imminent ischemia episodes, a physician may resort to interventional or surgical methods to repair the blockage.

 

Complications

Depending on which artery is blocked, atherosclerosis can cause several health problems.

1. Coronary artery disease and angina

Atherosclerosis of the main arteries leading to your heart can cause coronary artery disease (CAD) or angina. The heart is a muscle, and it, like all other muscles, requires an oxygen-rich blood supply. Blood flow to the heart can be slowed or stopped if one or more coronary arteries become narrowed or blocked. A heart attack can be caused by coronary artery disease.

Coronary microvascular disease can occur when plaque builds in the extremely tiny arteries of the heart. Even if testing indicate no blockages in the larger arteries, microvascular angina can induce chest discomfort.

    2. Carotid artery disease

Blood flow to the brain might decrease or cease if the arteries in your neck become narrowed or obstructed. A fragment of plaque can break off and travel through the arteries to the brain, where it can clog blood vessels and trigger a stroke or mini-stroke (TIA).

    3. Peripheral arterial disease (PAD)

Peripheral arterial disease (PAD) occurs when the arteries in your legs or arms become narrowed or blocked, resulting in cramping muscular pain while walking or exercising. Although pain in the leg is usually the first sign of PAD, it can occur anywhere in the body. It may also have an effect on the arteries that carry blood to your kidneys or stomach, raising the risk of organ damage.

    4. Aneurysm

An aneurysm is a protrusion in a weakening section of your arterial wall caused by atherosclerosis. The bulge has the potential to rupture and cause internal bleeding in the brain. When an aneurysm in the biggest artery (the aorta) bursts, it can be deadly.

 

Conclusion 

Atherosclerosis is a progressive disease characterized by lipid and fibrous element accumulation in the large arteries. Although advanced lesions can become large enough to block blood flow, the most serious clinical complication is an acute occlusion caused by the formation of a thrombus or blood clot, which can lead to myocardial infarction or stroke.

Thrombosis is usually linked with lesion rupture or erosion. It is now obvious that atherosclerosis is a chronic inflammatory disease that can be turned into an acute clinical event by plaque rupture and thrombosis, rather than an unavoidable degenerative consequence of aging.