Arteriosclerosis
Arteriosclerosis is a general term meaning a hardening or
thickening of the body's arteries. This
thickening of the arteries may be caused by atherosclerosis (see
below), the natural aging process, or
other reasons.
Atherosclersosis
Atherosclerosis is a condition resulting from
the buildup of plaque--fatty substances, cellular waste,
calcium, fibrin and other materials--on arterial walls.
To view a picture of a
normal
coronary artery in the heart (R), travel
to the
University of Utah's Pathology Laboratory for
Medical Education. To view
atherosclerosis
in an artery, visit the same site (R). The
University of Utah also shows an image of the
"fatty
streaks" within an aorta, the vessel
responsible for pumping oxygenated blood from the
heart to the rest of the body (R). For those
interested in learning more about
atherosclerosis, Peter Libby, MD, has a detailed
Quicktime audio presentation on the
"Pathogenesis
of the Atherosclerotic Plaque and Acute Coronary
Syndromes" (O--Quicktime software is required).
Atherosclerosis is thought to begin when the inner (endothelial)
lining of a blood vessel becomes damaged. Damage
is caused by smoking, high blood pressure (see above), or
other reasons. Once the vessel is damaged, it
bleeds and forms a clot. The damaged area
accumulates cholesterol, calcium, and fibrin more
easily, leading to the plaque buildup. Howard R. Horn, MD,
describes the role of endothelium to the atherosclerotic process
in his Medscape article, "Insulin
Resistance, Diabetes, and Vascular Disease" (O--you may
need to subscribe to Medscape in order to access the article,
but doing so is free). Atherosclerosis can occur in virtually any
arterial vessel. When arteries leading to the
heart become blocked, blood flow is compromised, which can
trigger angina and myocardial
infarction (see terminology, below).
Atherosclerosis can also prevent optimal blood
flow in the periphery of the body, such as the
legs, in a condition called peripheral arterial
disease. To learn more about peripheral arterial
disease, you can watch the online video at
HealthVideo.com,
"Peripheral
Arterial Disease: A Disease You Should Know
About" link (O), provided your browser can read
streaming media files with software like Real
Media.
Coronary Artery Disease (CAD)
Also known as coronary heart disease, this
condition refers to atherosclerosis of the heart's coronary arteries,
those vessels responsible for delivering fresh blood to the
muscle. The atherosclerotic plaque
buildup decreases blood flow to the heart muscle, interfering oxygen demands of the heart. You can see where
the coronary arteries are located by viewing an
illustration at the
Heart
Surgery Forum. (R) University of Utah's
Pathology Laboratory shows images of a
coronary
artery with approximately 60% occlusion i.e.
60% blocked, and an artery with even more occlusion (O).
Medmovie.com
provides an animation with more detailed
information than needed for this course, but the
animation may be helpful in better understanding
the atherosclerotic process in coronary arteries
(O).
Ischemia
When a body tissue does not receive adequate blood
flow, that tissue is said to be ischemic.
Atherosclerosis is one contributor to ischemia. That is,
plaque within a blood vessel can interfere with blood
flow to a target tissue. The feeling of ischemia is usually
described as
pressure, pain, or similar discomfort. For example, when a blood pressure
cuff is attached to the arm and pumped too high, blood flow to
the arm is compromised. The resulting discomfort in the arm is
caused by the ischemia. HealthCenter Online has more information
on
cardiac
ischemia (O).
Angina
When there is not enough blood flow (ischemia) to the
heart, an individual can experience
sensations of pressure or pain in the chest. This
pain is referred to as angina, or
angina pectoris.
Often, the discomfort may radiate into the arms,
back, shoulders and neck, which can mislead the
sufferer into thinking he or she is simply
fatigued. For more information on
angina,
visit the American Heart Association (O).
Myocardial Infarction
Another name for myocardial infarction is
"heart attack." Symptoms of a heart
attack include pain or tightness in the chest,
back, arms, and neck; nausea; an erratic pulse;
and perspiration due to a lack of blood flow to
the heart. When blood flow within any of the
heart's coronary arteries (the vessels delivering
fresh blood to the heart) is impeded, part of the
tissue starts to die--a myocardial infarction. To
view cardiac tissue after a
myocardial
infarction, travel to the University of
Utah's Pathology Laboratory for Medical Education
(O--WARNING: this link contains a sensitive
photo, a piece of heart tissue damaged from a
heart attack). For more information on myocardial
infarction visit the
Heart
Problems Clinic (O). Penn State's Biobehavioral Health
Department also has a photo of heart tissue affected by a
myocardial
infarction (O--WARNING: SENSITIVE PHOTO).
In 2001 the
American College of Cardiology (ACC), in conjunction with
the European Society of Cardiology, broadened the
definition of heart attack to include individuals
who have experienced severe, stable, or unstable
angina AND who have tested positive for a
specific amount of cardiac troponin (a heart
protein). Troponin tends to appear in higher
levels in the blood after an acute heart attack. A new,
broadened heart attack definition means the
number of people diagnosed with a heart attack
will increase. Similarly, in 2007, four
international organizations agreed upon new criteria for
diagnosing heart attacks. Prior to 2007, a heart attack
diagnosis was made if a patient exhibited two of the three
following criteria: heart attack symptoms (chest
pain/pressure, shortness of breath, etc.), an abnormal
electrocardiogram, and a change in certain biomarker levels
in the blood. In 2007, the organizations specifically
recognized troponin as an additional criterion, since
presence of the substance indicates heart cell damage. For an online animation of heart attack,
travel to www.5min.com to
watch, "What
is a Heart Attack" (R).
The
HeartCenter
Online provides an animation and audio
presentation describing coronary artery disease
and heart attack (O--highly recommended but not
required).
Learning these cardiovascular terms and
noting how they relate to each other can be challenging.
Medmovie.com shows a flash
animation showing how atherosclerosis in the coronary
arteries of the heart (coronary artery disease) can lead to a
myocardial infarction (O--highly recommended for students
wanting to view the relationship of these conditions)
If you have RealPlayer software, you can
travel to the National Heart, Lung and Blood Institute to view a
video of a
heart
attack in progress (O).
The British Heart Foundation supported the
creation of a video clip,
What is a
Heart Attack? (O)
Arrhythmia
An abnormal heart beat is known as arrhythmia.
The abnormal beat can be one that is too fast
(tachycardia), too slow (bradycardia), or simply
irregular, usually due to some underlying
disease. For more information on
arrhythmias,
refer to the American Heart Association. (O)
The heart's
electrical system is described in an audiovisual animation
at the National Heart Lung and Blood Institute (R). To see an animation of normal
"sinus" heart rhythm, travel to WebMD
to view the animation of
sinus
rhythm (R). To view arrhythmia
animations, travel to medmovie.com, click on the "forward"
button, and select the
arrhythmias you wish to view (O).
An arrhythmia can be detected through a test
called an electrocardiogram (ECG or EKG). The
Heart
Problems Clinic features examples of what
ECG's look like in the case of tachycardia and in
a premature beat (O--click on "Arrhythmias" to view
ECG patterns). In some patients,
pacemakers may be required for specific
arrhythmias. St. Jude Medical provides a
frequently asked questions about pacemakers link
(O). Medtronic posts information about how
pacemakers interact with
daily living, and offers precautions regarding pacemakers
and some specific medical procedures (O).
Educational
Enrichment
Diagnosing
Tachycardia at Hearthelp.com
New
York University EKG Tutorial
Cardiac Arrest
Cardiac arrest is different from heart attack. Whereas a heart attack is caused by
a halting of blood flow to the cardiac muscle,
cardiac arrest is an electrical event causing the
heart to stop beating. Listen more about the difference between
a heart attack and cardiac arrest at 5min.com by
watching the short video clip
Sudden Cardiac Arrest vs Heart Attack
(R). Ventricular fibrillation,
a specific type of arrhythmia, can lead to
cardiac arrest. The electrical problems
experienced in cardiac arrest are usually the
result of some underlying cardiovascular disease.
Travel to
Merck.com
to read a description of ventricular fibrillation
(R). The site also contains images of electrocardiograms: one
normal and the other showing ventricular fibrillation. To view
an animation of
ventricular fibrillation, travel to the National Heart Lung
and Blood Institute's website, then scroll down the webpage to
the last animation (O).
Although cardio-pulmonary resuscitation (CPR)
is a valuable skill which may help in sustaining
life, many organizations recommend
automated external defibrillators (AED) be
installed in public places in the event of
cardiac arrest. Automated external defibrillators
(AED's) are portable devices used to defibrillate
the heart during cardiac arrest. You can see how
an AED operates by traveling to
Philips Medical Systems
HeartStart FR2+ Demo links to view an AED demonstration. For
a cardiac arrest demo, travel to
Physio-Control
(O). For more
information on AED, read "What is an AED and
how does it work," as well as
"Effectiveness of AED" at the
Heart
and Stroke Foundation of Canada. (R)
Thrombus
A thrombus is when a piece of tissue, a blood
clot or other foreign body present in a blood
vessel prevents adequate blood delivery, which
could lead to tissue damage or tissue death. In
cardiovascular disease, a thrombus is usually
caused by a blood clot existing in a blood
vessel. These clots can form whenever the vessel
is damaged. The damaged vessel will bleed, and
the bleeding will eventually stop through the
normal clotting process. The clot can decrease
blood flow to tissue, or it can completely impede
blood flow. The Stroke Center has an image of a
thrombus
(O). For those interested in more information,
Peter Libby, MD presents a detailed audio
Quicktime feature, "Multiple
Mechanisms of Arterial Thrombosis" (O--QuickTime
software needed).
Embolus
An embolus is when a piece of tissue, a blood
clot or other foreign body circulates in the
blood and becomes trapped in a blood vessel too
small to let it pass. In cardiovascular disease,
an embolus may occur when a thrombus has
detached, travels to another blood vessel and
slows or stops blood flow at the new site. Travel to
HeartCenterOnline.com to view an image of an
embolus
in a blood vessel (R).
Stroke
A stroke occurs when part of the brain dies
because it does not receive the blood that it
needs. Marked by a sudden weakness,
numbness or paralysis in certain parts of the
body, sudden speech, sight, walking or thinking
changes, a stroke can occur as a result of a
blockage (embolus, thrombus), which is the most
common reason, or through bleeding (an aneurysm
or hemorrhage). To see an animation related to
stroke
and its causes (embolus, thrombus, atherosclerosis), visit the
University of Maryland Medical Center (O). To read
about
symptoms
of stroke, visit the Mayo Clinic (O).
The Centers for Disease Control and Prevention describe
racial
and ethnic disparities in stroke (O).
In 2008, the
Stroke
Collaborative--a joint venture among the American Academy of
Neurology, the American College of Emergency Physicians, and the
American Heart Association--is trying to educate the general
public on five stroke symptoms (O).
Congestive Heart Failure
A diseased heart is not able to pump blood
effectively. As a result, the blood "backs
up" in the veins leading to the heart, which
can lead to pulmonary (lung) congestion. Symptoms
include swelling in the legs, ankles, and an
inability of the kidneys to excrete water and
sodium efficiently, making the swelling worse.
Congestive heart failure is usually diagnosed
through a variety of exams: a blood test, a
physical, medical history evaluation,
catheterization, ECG, echocardiogram, and chest
x-ray are often used. You can see an x-ray of a normal heart and
an
enlarged
heart at the Franklin Institute
(O).
Myhealth.com provides an illustration showing the difference
between a normal-sized and enlarged heart (O). A sensitive photo
via
National Geographic shows a medical worker holding up a
normal-sized heart and an enlarged heart (O--WARNING: SENSITIVE
PHOTO).
Rheumatic Heart Failure
This condition is the result of rheumatic
heart fever, in which heart valve damage occurs
after a strep infection. This is one reason why
physicians take strep throat so seriously in
children. In rheumatic fever, the inner lining of
the heart is inflammed and the valves may scar, causing an
inability for them to open or close properly (heart murmur).
This condition may eventually require a valve replacement. To
hear a heart murmur, visit the
University of Michigan Health System (O).
Educational
Enrichment
Understanding
High Blood Pressure, by the National Heart,
Lung and Blood Institute
One of the most common medications used is Coumadin,
used to decrease the risk for blood clotting, as
described at the Heart Surgery Forum
The
Top 10 Research Advances of the American
Heart Association
The
Nurses Health Study, Harvard University
Men
and Heart Disease: An Atlas of Racial and Ethnic
Disparities in Mortality (CDC, a pdf file)
WebMD describes how the
heart compensates for heart failure
InteractivePhysiology.com has a tutorial
on
blood pressure regulation
Last Revised: 1-14-10
