An atheroma, or atheromatous plaque, is an abnormal accumulation of material in the
inner layer of an
arterial
An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...
wall.
The material consists of mostly
macrophage cells,
or debris, containing
lipids
Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins Vitamin A, A, Vitamin D, D, Vitamin E, E and Vitamin K, K), monoglycerides, diglycerides, phospholipids, and others. The fu ...
, calcium and a variable amount of fibrous
connective tissue
Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...
. The accumulated material forms a swelling in the artery wall, which may intrude into the
lumen of the artery,
narrowing it and restricting blood flow. Atheroma is the
pathological basis for the disease entity
atherosclerosis
Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...
, a subtype of
arteriosclerosis
Arteriosclerosis, literally meaning "hardening of the arteries", is an umbrella term for a vascular disorder characterized by abnormal thickening, hardening, and loss of elasticity of the walls of arteries; this process gradually restricts th ...
.
Signs and symptoms
For most people, the first symptoms result from atheroma progression within the
heart arteries, most commonly resulting in a
heart attack
A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
and ensuing debility. The heart arteries are difficult to track because they are small (from about 5 mm down to microscopic), they are hidden deep within the chest and they never stop moving. Additionally, all mass-applied clinical strategies focus on both minimal cost and the overall safety of the procedure. Therefore, existing diagnostic strategies for detecting atheroma and tracking response to treatment have been extremely limited. The methods most commonly relied upon, patient symptoms and
cardiac stress testing
A cardiac stress test is a cardiological examination that evaluates the cardiovascular system's response to external stress within a controlled clinical setting. This stress response can be induced through physical exercise (usually a treadmill) o ...
, do not detect any symptoms of the problem until atheromatous disease is very advanced because arteries enlarge, not constrict, in response to increasing atheroma.
It is plaque ruptures, producing debris and clots which obstruct blood flow downstream, sometimes also locally (as seen on
angiograms), which reduce/stop blood flow. Yet these events occur suddenly and are not revealed in advance by either
stress tests or
angiograms.
Mechanism
The healthy epicardial coronary artery consists of three layers, the
tunica intima
The tunica intima (Neo-Latin "inner coat"), or intima for short, is the innermost tunica (biology), tunica (layer) of an artery or vein. It is made up of one layer of endothelium, endothelial cells (and macrophages in areas of disturbed blood flo ...
, media, and
adventitia
The adventitia ( ) is the outer layer of fibrous connective tissue surrounding an organ.
The outer layer of connective tissue that surrounds an artery, or vein – the tunica externa, is also called the ''tunica adventitia''.
To some degree, i ...
.
Atheroma and changes in the artery wall usually result in small
aneurysm
An aneurysm is an outward :wikt:bulge, bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also b ...
s (enlargements) just large enough to compensate for the extra wall thickness with no change in the lumen diameter. However, eventually, typically as a result of rupture of
vulnerable plaque
A vulnerable plaque is a kind of atheromatous plaque – a collection of white blood cells (primarily macrophages) and lipids (including cholesterol) in the wall of an artery – that is particularly unstable and prone to produce sudden major pr ...
s and clots within the lumen over the plaque,
stenosis
Stenosis () is the abnormal narrowing of a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture).
''Stricture'' as a term is usually used when narrowing ...
(narrowing) of the vessel develops in some areas. Less frequently, the artery enlarges so much that a gross aneurysmal enlargement of the artery results. All three results are often observed, at different locations, within the same individual.
Stenosis and closure
Over time, atheromata usually progress in size and thickness and induce the surrounding muscular central region (the media) of the
artery
An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...
to stretch out, which is termed ''remodeling''. Typically, remodeling occurs just enough to compensate for the atheroma's size such that the
calibre of the artery opening (
lumen) remains unchanged, until about 50% of the artery wall cross-sectional area consists of atheromatous tissue.
[
]
If the muscular wall enlargement eventually fails to keep up with the enlargement of the atheroma volume, or a clot forms and organizes over the plaque, then the lumen of the artery becomes narrowed as a result of repeated ruptures, clots and fibrosis over the tissues separating the atheroma from the blood stream. This narrowing becomes more common after decades of living, increasingly more common after people are in their 30s to 40s.
The endothelium
The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the r ...
(the cell monolayer on the inside of the vessel) and covering tissue, termed fibrous cap, separate atheroma from the blood in the lumen. If a rupture (see vulnerable plaque
A vulnerable plaque is a kind of atheromatous plaque – a collection of white blood cells (primarily macrophages) and lipids (including cholesterol) in the wall of an artery – that is particularly unstable and prone to produce sudden major pr ...
) of the endothelium and fibrous cap occurs, then both a shower of debris from the plaque (debris larger than 5 micrometres are too large to pass through capillaries
A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima (the in ...
) combined with a platelet
Platelets or thrombocytes () are a part of blood whose function (along with the coagulation#Coagulation factors, coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a thrombus, blood clot. Platelets have no ...
and clotting response (an injury/repair response to both the debris and at the rupture site) begins within fractions of a second, eventually resulting in narrowing or sometimes closure of the lumen. Eventually downstream tissue damage occurs due to closure or obstruction of downstream microvessels and/or closure of the lumen at the rupture, both resulting in loss of blood flow to downstream tissues. This is the principal mechanism of myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
, stroke
Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...
or other related cardiovascular disease
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...
problems.
While clots at the rupture site typically shrink in volume over time, some of the clot may become organized into fibrotic tissue resulting in narrowing of the artery lumen; the narrowings sometimes seen on angiography
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfo ...
examinations, if severe enough. Since angiography methods can only reveal larger lumens, typically larger than 200 micrometres, angiography after a cardiovascular event commonly does not reveal what happened.
Artery enlargement
If the muscular wall enlargement is overdone over time, then a gross enlargement of the artery results, usually over decades of living. This is a less common outcome. Atheroma within aneurysmal enlargement (vessel bulging) can also rupture and shower debris of atheroma and clot downstream. If the arterial enlargement continues to 2 to 3 times the usual diameter, the walls often become weak enough that with just the stress of the pulse, a loss of wall integrity may occur leading to sudden hemorrhage
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, ...
(bleeding), major symptoms and debility; often rapid death. The main stimulus for aneurysm formation is pressure atrophy of the structural support of the muscle layers. The main structural proteins are collagen
Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
and elastin
Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...
. This causes thinning and the wall balloons allowing gross enlargement to occur, as is common in the abdominal region of the aorta.
Histology
The accumulation (swelling) is always in the tunica intima, between the endothelium
The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the r ...
lining and the smooth muscle middle layer of the artery wall. While the early stages, based on gross appearance, have traditionally been termed fatty streaks by pathologists, they are not composed of fat cells but of accumulations of white blood cells
White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...
, especially macrophages
Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...
, that have taken up oxidized low-density lipoprotein
Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall density ...
(LDL).
After they accumulate large amounts of cytoplasmic membranes (with associated high cholesterol content) they are called foam cells. When foam cells die, their contents are released, which attracts more macrophages and creates an extracellular lipid core near the centre to inner surface of each atherosclerotic plaque.
Conversely, the outer, older portions of the plaque become more calcified, less metabolically active and more physically stiff over time.
Vein
Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...
s do not develop atheromata, because they are not subjected to the same haemodynamic pressure that arteries are, unless surgically moved to function as an artery, as in bypass surgery. In fact, veins grafted to function as arteries in bypass surgeries tend to show faster formation of atheromata, while (in rabbits) arteries grafted to function as veins also do not grow atheromata.
Diagnosis
Because artery walls enlarge at locations with atheroma,[ detecting atheroma before death and autopsy has long been problematic at best. Most methods have focused on the openings of arteries; while these methods are highly relevant, they totally miss the atheroma within the arterial lumen.
Historically, arterial wall fixation, staining and thin section has been the gold standard for detection and description of atheroma, after death and autopsy. With special stains and examination, micro calcifications can be detected, typically within smooth muscle cells of the arterial media near the fatty streaks within a year or two of fatty streaks forming.
Interventional and non-interventional methods to detect atherosclerosis, specifically ]vulnerable plaque
A vulnerable plaque is a kind of atheromatous plaque – a collection of white blood cells (primarily macrophages) and lipids (including cholesterol) in the wall of an artery – that is particularly unstable and prone to produce sudden major pr ...
(non-occlusive or soft plaque), are widely used in research and clinical practice today.
Carotid Intima-media thickness Scan (CIMT can be measured by B-mode ultrasonography
Medical ultrasound includes diagnostic techniques (mainly imaging) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, ...
) measurement has been recommended by the American Heart Association
The American Heart Association (AHA) is a nonprofit organization in the United States that funds cardiovascular medical research, educates consumers on healthy living and fosters appropriate Heart, cardiac care in an effort to reduce disability ...
as the most useful method to identify atherosclerosis and may now very well be the gold standard for detection.
Intravascular ultrasound
Intravascular ultrasound (IVUS) or intravascular echocardiography is a medical imaging methodology using a specially designed catheter with a miniaturized ultrasound probe attached to the distal end of the catheter. The proximal end of the cathe ...
and intravascular optical coherence tomography are the current most sensitive method detecting and measuring more advanced atheroma within living individuals, but has had limited applications due to cost and body invasiveness.
CT scan
A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...
s using state of the art higher resolution spiral, or the higher speed EBT, machines have been the most effective method for detecting calcification present in plaque. However, the atheroma have to be advanced enough to have relatively large areas of calcification within them to create large enough regions of ~130 Hounsfield units which a CT scanner's software can recognize as distinct from the other surrounding tissues. Typically, such regions start occurring within the heart arteries about 2–3 decades after atheroma start developing. The presence of smaller, spotty plaques may actually be more dangerous for progressing to acute myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
.
Arterial ultrasound, especially of the carotid arteries, with measurement of the thickness of the artery wall, offers a way to partially track the disease progression. As of 2006, the thickness, commonly referred to as IMT for intimal-medial thickness, is not measured clinically though it has been used by some researchers since the mid-1990s to track changes in arterial walls. Traditionally, clinical carotid ultrasounds have only estimated the degree of blood lumen restriction, stenosis
Stenosis () is the abnormal narrowing of a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture).
''Stricture'' as a term is usually used when narrowing ...
, a result of very advanced disease. The National Institute of Health
The National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. It was founded in 1887 and is part of the United States Department of Health and Human Servic ...
did a five-year $5 million study, headed by medical research
Medical research (or biomedical research), also known as health research, refers to the process of using scientific methods with the aim to produce knowledge about human diseases, the prevention and treatment of illness, and the promotion of ...
er Kenneth Ouriel, to study intravascular ultrasound techniques regarding atherosclerotic plaque. More progressive clinicians have begun using IMT measurement as a way to quantify and track disease progression or stability within individual patients.
Angiography
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfo ...
, since the 1960s, has been the traditional way of evaluating for atheroma. However, angiography is only motion or still images of dye mixed with the blood within the arterial lumen and never show atheroma; the wall of arteries, including atheroma within the arterial wall remain invisible. The limited exception to this rule is that with very advanced atheroma, with extensive calcification within the wall, a halo-like ring of radiodensity can be seen in most older humans, especially when arterial lumens are visualized end-on. On cine-floro, cardiologists and radiologists typically look for these calcification shadows to recognize arteries before they inject any contrast agent
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiop ...
during angiograms.
Classification of lesions
* Type I: Isolated macrophage foam cells
* Type II: Multiple foam cell layers[
* Type III: Preatheroma, intermediate lesion][
* Type IV: Atheroma][
* Type V: Fibroatheroma][
* Type VI: Fissured, ulcerated, hemorrhagic, thrombotic lesion][
* Type VII: Calcific lesion][
* Type VIII: Fibrotic lesion][
]
Treatment
Many approaches have been promoted as methods to reduce or reverse atheroma progression:
* eating a diet of raw fruits, vegetables, nuts, beans, berries, and grains;
* consuming foods containing omega−3 fatty acids such as fish, fish-derived supplements, as well as flax seed oil, borage oil, and other non-animal-based oils;
* abdominal fat reduction;
* aerobic exercise;
* inhibitors of cholesterol
Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils.
Cholesterol is biosynthesis, biosynthesized by all anima ...
synthesis (known as statins
Statins (or HMG-CoA reductase inhibitors) are a class of medications that lower cholesterol. They are prescribed typically to people who are at high risk of cardiovascular disease.
Low-density lipoprotein (LDL) carriers of cholesterol play ...
);
* low normal blood glucose
The blood sugar level, blood sugar concentration, blood glucose level, or glycemia is the measure of glucose concentrated in the blood. The body tightly blood sugar regulation, regulates blood glucose levels as a part of metabolic homeostasis ...
levels ( glycated hemoglobin, also called HbA1c);
* micronutrient (vitamins, potassium
Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
, and magnesium
Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...
) consumption;
* maintaining normal, or healthy, blood pressure levels;
* aspirin supplement
* mouse studies indicated that subcutaneous administration of oligosaccharide 2-hydroxypropyl-β-cyclodextrin (2HPβCD) can solubilize cholesterol
Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils.
Cholesterol is biosynthesis, biosynthesized by all anima ...
, removing it from plaques. However, later work concluded that "treatment with 2HPβCD is ineffective in inducing atherosclerosis regression".
When a plaque is dangerous enough, it may warrant physical intervention such as percutaneous coronary intervention
Percutaneous coronary intervention (PCI) is a minimally invasive non-surgical procedure used to treat stenosis, narrowing of the coronary artery, coronary arteries of the heart found in coronary artery disease. The procedure is used to place and ...
, coronary artery bypass graft, or carotid endarterectomy
Carotid endarterectomy is a surgical procedure used to reduce the risk of stroke from carotid artery stenosis (narrowing the internal carotid artery). In an endarterectomy, the surgeon opens the artery and removes the plaque. The plaque forms ...
. Of these, endarterectomy involves cutting open the affected artery to remove the plaque.
History of research
In developed countries
A developed country, or advanced country, is a sovereign state that has a high quality of life, developed economy, and advanced technological infrastructure relative to other less industrialized nations. Most commonly, the criteria for eval ...
, with improved public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the de ...
, infection control and increasing life spans, atheroma processes have become an increasingly important problem and burden for society.
Atheromata continue to be the primary underlying basis for disability
Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be Cognitive disability, cognitive, Developmental disability, d ...
and death
Death is the end of life; the irreversible cessation of all biological functions that sustain a living organism. Death eventually and inevitably occurs in all organisms. The remains of a former organism normally begin to decompose sh ...
, despite a trend for gradual improvement since the early 1960s (adjusted for patient age). Thus, increasing efforts towards better understanding, treating and preventing the problem are continuing to evolve.
According to United States data, 2004, for about 65% of men and 47% of women, the first symptom
Signs and symptoms are diagnostic indications of an illness, injury, or condition.
Signs are objective and externally observable; symptoms are a person's reported subjective experiences.
A sign for example may be a higher or lower temperature ...
of cardiovascular disease is myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
(heart attack) or sudden death (death within one hour of symptom onset).
A significant proportion of artery flow-disrupting events occur at locations with less than 50% lumenal narrowing. Cardiac stress test
A cardiac stress test is a cardiological examination that evaluates the cardiovascular system's response to external stress within a controlled clinical setting. This stress response can be induced through physical exercise (usually a treadmill) o ...
ing, traditionally the most commonly performed non-invasive testing method for blood flow limitations, generally only detects lumen narrowing greater than about 75%, although some physicians advocate nuclear stress tests that can sometimes detect as little as 50%.
The sudden nature of the complications of pre-existing atheroma, vulnerable plaque
A vulnerable plaque is a kind of atheromatous plaque – a collection of white blood cells (primarily macrophages) and lipids (including cholesterol) in the wall of an artery – that is particularly unstable and prone to produce sudden major pr ...
(non-occlusive or soft plaque), have led, since the 1950s, to the development of intensive care units and complex medical and surgical interventions. Angiography
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfo ...
and later cardiac stress testing
A cardiac stress test is a cardiological examination that evaluates the cardiovascular system's response to external stress within a controlled clinical setting. This stress response can be induced through physical exercise (usually a treadmill) o ...
was begun to either visualize or indirectly detect stenosis
Stenosis () is the abnormal narrowing of a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture).
''Stricture'' as a term is usually used when narrowing ...
. Next came bypass surgery, to plumb transplanted vein
Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...
s, sometimes arteries
An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...
, around the stenoses and more recently angioplasty
Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty, is a minimally invasive procedure, minimally invasive endovascular surgery, endovascular Medical procedure, procedure used to widen narrowed or obstructe ...
, now including stent
In medicine, a stent is a tube usually constructed of a metallic alloy or a polymer. It is inserted into the Lumen (anatomy), lumen (hollow space) of an anatomic vessel or duct to keep the passageway open.
Stenting refers to the placement of ...
s, most recently drug coated stents, to stretch the stenoses more open.
Yet despite these medical advances, with success in reducing the symptoms of angina
Angina, also known as angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease.
Angina is typically the result of parti ...
and reduced blood flow
Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory system is controlled by homeostasis, homeostatic mechanisms of autoregulation, just as hydrau ...
, atheroma rupture events remain the major problem and still sometimes result in sudden disability and death despite even the most rapid, massive and skilled medical and surgical intervention available anywhere today. According to some clinical trials, bypass surgery and angioplasty procedures have had at best a minimal effect, if any, on improving overall survival. Typically mortality of bypass operations is between 1 and 4%, of angioplasty between 1 and 1.5%.
Additionally, these vascular interventions are often done only after an individual is symptomatic, often already partially disabled, as a result of the disease. It is also clear that both angioplasty and bypass interventions do not prevent future heart attack
A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
.
The older methods for understanding atheroma, dating to before World War II, relied on autopsy data. Autopsy data has long shown initiation of fatty streaks in later childhood with slow asymptomatic progression over decades.[
One way to see atheroma is the very invasive and costly IVUS ultrasound technology; it gives us the precise volume of the inside intima plus the central ]media
Media may refer to:
Communication
* Means of communication, tools and channels used to deliver information or data
** Advertising media, various media, content, buying and placement for advertising
** Interactive media, media that is inter ...
layers of about of artery length. Unfortunately, it gives no information about the structural strength of the artery. Angiography does not visualize atheroma; it only makes the blood flow within blood vessels
Blood vessels are the tubular structures of a circulatory system that transport blood throughout many animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the tissues of a body. They also take waste an ...
visible. Alternative methods that are non or less physically invasive and less expensive per individual test have been used and are continuing to be developed, such as those using computed tomography
A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...
(CT; led by the electron beam tomography form, given its greater speed) and magnetic resonance imaging
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...
(MRI). The most promising since the early 1990s has been EBT, detecting calcification within the atheroma before most individuals start having clinically recognized symptoms and debility. Statin therapy (to lower cholesterol) does not slow the speed of calcification as determined by CT scan. MRI coronary vessel wall imaging, although currently limited to research studies, has demonstrated the ability to detect vessel wall thickening in asymptomatic high risk individuals. As a non-invasive, ionising radiation free technique, MRI based techniques could have future uses in monitoring disease progression and regression. Most visualization techniques are used in research, they are not widely available to most patients, have significant technical limitations, have not been widely accepted and generally are not covered by medical insurance carriers.
From human clinical trials, it has become increasingly evident that a more effective focus of treatment is slowing, stopping and even partially reversing the atheroma growth process. There are several prospective epidemiologic studies including the Atherosclerosis Risk in Communities (ARIC) Study and the Cardiovascular Health Study (CHS), which have supported a direct correlation of Carotid Intima-media thickness (CIMT) with myocardial infarction and stroke risk in patients without cardiovascular disease history. The ARIC Study was conducted in 15,792 individuals between 5 and 65 years of age in four different regions of the US between 1987 and 1989. The baseline CIMT was measured and measurements were repeated at 4- to 7-year intervals by carotid B mode ultrasonography in this study. An increase in CIMT was correlated with an increased risk for CAD. The CHS was initiated in 1988, and the relationship of CIMT with risk of myocardial infarction and stroke was investigated in 4,476 subjects 65 years of age and below. At the end of approximately six years of follow-up, CIMT measurements were correlated with cardiovascular events.
Paroi artérielle et Risque Cardiovasculaire in Asia Africa/Middle East and Latin America (PARC-AALA) is another important large-scale study, in which 79 centres from countries in Asia, Africa, the Middle East, and Latin America participated, and the distribution of CIMT according to different ethnic groups and its association with the Framingham cardiovascular score was investigated. Multi-linear regression analysis revealed that an increased Framingham cardiovascular score was associated with CIMT, and carotid plaque independent of geographic differences.
Cahn et al. prospectively followed-up 152 patients with coronary artery disease for 6–11 months by carotid artery ultrasonography and noted 22 vascular events (myocardial infarction, transient ischemic attack, stroke, and coronary angioplasty) within this time period. They concluded that carotid atherosclerosis measured by this non-interventional method has prognostic significance in coronary artery patients.
In the Rotterdam Study
The Rotterdam Study or ERGO (Dutch language, Dutch: ''Erasmus Rotterdam Gezondheid Onderzoek'') is a Prospective cohort study, prospective, Population based study, population-based cohort study. The aim of the Rotterdam Study is to investigate etio ...
, Bots et al. followed 7,983 patients >55 years of age for a mean period of 4.6 years, and reported 194 incident myocardial infarctions within this period. CIMT was significantly higher in the myocardial infarction group compared to the other group. Demircan et al. found that the CIMT of patients with acute coronary syndrome were significantly increased compared to patients with stable angina pectoris.
It has been reported in another study that a maximal CIMT value of 0.956 mm had 85.7% sensitivity and 85.1% specificity to predict angiographic CAD. The study group consisted of patients admitted to the cardiology outpatient clinic with symptoms of stable angina pectoris. The study showed CIMT was higher in patients with significant CAD than in patients with non-critical coronary lesions. Regression analysis revealed that thickening of the mean intima-media complex more than 1.0 was predictive of significant CAD our patients. There was incremental significant increase in CIMT with the number coronary vessel involved. In accordance with the literature, it was found that CIMT was significantly higher in the presence of CAD. Furthermore, CIMT was increased as the number of involved vessels increased and the highest CIMT values were noted in patients with left main coronary involvement. However, human clinical trials have been slow to provide clinical & medical evidence, partly because the asymptomatic nature of atheromata make them especially difficult to study. Promising results are found using carotid intima-media thickness scanning (CIMT can be measured by B-mode ultrasonography), B-vitamins that reduce a protein corrosive, homocysteine and that reduce neck carotid artery plaque volume and thickness, and stroke, even in late-stage disease.
Additionally, understanding what drives atheroma development is complex with multiple factors involved, only some of which, such as lipoprotein
A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, sur ...
s, more importantly lipoprotein subclass analysis, blood sugar
The blood sugar level, blood sugar concentration, blood glucose level, or glycemia is the measure of glucose concentrated in the blood. The body tightly regulates blood glucose levels as a part of metabolic homeostasis.
For a 70 kg (1 ...
levels and hypertension
Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...
are best known and researched. More recently, some of the complex immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
patterns that promote, or inhibit, the inherent inflammatory macrophage triggering processes involved in atheroma progression are slowly being better elucidated in animal models of atherosclerosis.
See also
* Angiogram
* ApoA-1 Milano
* Atherosclerosis
Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...
* Atherothrombosis
* Coronary circulation
Coronary circulation is the Circulatory system#Coronary vessels, circulation of blood in the arteries and veins that supply the cardiac muscle, heart muscle (myocardium).
Coronary arteries supply oxygen saturation (medicine), oxygenated blood to ...
* Coronary catheterization
A coronary catheterization is a minimally invasive procedure to access the coronary circulation and blood filled chambers of the heart using a catheter. It is performed for both diagnostic and interventional (treatment) purposes.
Coronary cathet ...
* EBT
* Hemorheologic-Hemodynamic Theory of Atherosclerosis
* Lipoprotein
A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, sur ...
* LDL, HDL, IDL and VLDL
Very-low-density lipoprotein (VLDL), density relative to extracellular water, is a type of lipoprotein made by the liver. VLDL is one of the five major groups of lipoproteins (chylomicrons, VLDL, intermediate-density lipoprotein, LDL, low-density ...
References
Further reading
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External links
{{Vascular diseases
Vascular diseases
Diseases of arteries, arterioles and capillaries