Heart
The heart is a muscular organ whose interior is divided into two pairs
of chambers, one on the right, the other on the left; the chambers of
each pair are connected with each other by a valve. Lying in the
mid-left section of the chest, close to the breastbone, the human heart
weighs about 12 ounces, beats 70 to 80 times a minute, and is enclosed
by a sturdy membrane called pericardium. Its chambers are lined by a
delicate membrane, the endocardium, and its vigorous muscular and
connective tissues are nourished by the heart’s own blood vessels, the
coronary vessels.
How the Heart Works
This remarkable muscle serves as a pump controlling the blood stream in
two circuits, the pulmonary and the systemic. The right side of the
heart receives the blood from the large veins that drain the systemic
circuit and propels it into the lungs where carbon dioxide is removed
and oxygen is picked up. The oxygenated blood, collecting in the
pulmonary veins, than enters the left side of the heart, from which it
is pumped out again into the systemic circulation by way of the body’s
largest blood vessel, the aorta. The rhythmic pumping is in the form of
a repeated contraction ( systole ) and relaxation (diastole). Every 60
seconds, this precisely adjusted human pump drives about five quarts of
blood through the body.
Auricles and Ventricles
The four chambers of the heart have special roles in the pumping
process. The upper chambers are called the auricles; the lower chambers,
the ventricles. The auricle and ventricle on each side together form an
independent part of the heart, somewhat like a duplex apartment; in
effect, they make up a “right heart” and a “left heart”. There is no
connection for the blood into the pulmonary circuit, the left into the
general body circuit.
Valves of the heart
Between the right auricle and right ventricle is a valve, called the
tricuspid valve. Similarly, the left auricle and left ventricle are
connected by the mitral valve, so named because of its apparent
resemblance to a bishop’s miter or tall cap. The sounds of the valves
opening and closing are heard by the doctor when he listens with his
stethoscope. In addition to the valves between auricle and ventricle on
each side of the heart, there are valves at the blood’s exit points: the
pulmonary valve opening from the right ventricle into the pulmonary
artery, and the aortic valve opening from the left ventricle into the
aorta. All these valves, both within the heart and leading out of it,
open shut in such a way is to keep the blood flowing only in one
direction through the heart’s two separate pairs of chambers: from
auricle to ventricle and out through its appropriate artery.
A Single Pumping Action
Although the right and left sides of the heart serve two separate
branches of the circulation, each with its distinct function, they are
co-ordinated so that the heart efficiently serves both sides with a
single pumping action. The valve action on both sides is also
co-ordinated with the two phases of the pumping action. Thus, during the
diastole, or relaxation phase, the oxygen-poor blood which was
accumulated in the right auricle returning from the systemic or body
circulation pours into the right ventricle. At the same time, the
oxygen-rich blood which was accumulated in the left auriclereturning
from the pulmonary circulation pours into the left ventricle. The weak
walls of both auricles contract to press the blood into the relaxed
ventricles. In the next or contraction phase, the systole, the valve
between auricle and ventricle on each side closes, and the muscular
walls contract the ventricles and sweep the blood through each passage
into the pulmonary artery and the aorta. At the end of the contraction
the pulmonary and aortic valves snap shut, preventing any backward surge
of the blood to the ventricles. The diastole follows, the ventricles
again fill with the flow from their separate auricles and the cycle is
repeated. This co-ordinated rhythmic action goes on tirelessly day and
night throughout every individual’s lifetime.
The Valve Cusps
The valves, which must withstand considerable pressure, are composed of
a special type of tough tissue. The mitral valve, between the left
auricle and ventricle, has two cusps or leaflets. The tricuspid valve,
between the right auricle and ventricle, has three cusps. Both valves
function in the same manner. When blood pressure in auricle is higher
than in the ventricle, the valve leaflets are swept open; as the blood
flows downward, the auricular contraction at the start of the heart beat
helps to push the blood along. As the blood fills the ventricle, the
leaflets close, and with the contraction of the ventricle, pressure
tightly shuts the valve. The valve leaflets are bolstered from below by
a set of tough tendons with muscular attachments, enabling the leaflets
to withstand the pressure and keep the valves from opening inward into
the auricle.
The two valves which control the exit passages from the heart, the
aortic valve and the pulmonary valve, have three leaflets each, and they
also only for one-way flow. Other valves at special stations along the
line in the circulatory system keep the blood from pooling in the lower
extremities of the body.
Heart Disease.
Heart disease, the leading cause of death, is a term covering a variety
of more than 20 different diseases of the heart and blood vessels. The
most common of these are rheumatic heart disease, hypertension or high
blood pressure, and coronary artery disease. Other forms of heart
disease can be caused by congenital malformations of the heart and major
vessels, syphilis, diphtheria, abnormal functioning of the thyroid
gland, or diseases resulting from vitamin deficiencies.
Although approximately ten million Americans have some form of heart
disease, the tremendous advances made by medical science have made it
possible to treat and control these illnesses with increasing success.
The majority of individuals who suffer a heart attack recover, and
recurrent attacks of rheumatic fever which injure the heart can now
frequently be prevented. By means of modern surgical techniques, heart
defects and heart damage may often be repaired by HEART SURGERY.
To clarify various descriptions of heart ailments, it should be
understood that a “heart attack” is not strictly the same as “heart
disease”. A heart attack usually signifies the sudden obstruction of a
coronary artery, one of the blood vessels feeding blood to the heart
muscle; the clogging of the artery by a blood clot cuts off the blood
supply to an area of the heart muscle. There is also a distinction
between a heart attack, heart disease, and “heart failure”. Heart
failure does not mean that the heart has stopped beating but that the
heart is not pumping efficiently and the body’s blood circulation is
being affected by the change.
One of the most prevalent of the diseases involving the heart is
arteriosclerosis, commonly known as hardening of the arteries. Diseases
of other organs of the body can also produce heart disease; one of these
is nephritis, a disease of the kidneys which affects the tiny blood
vessels or capillaries. Another such disease is diabetes which in some
individuals may injure the blood vessels in much the same fashion as
does high blood pressure.
Symptoms
Symptoms of heart disease may include certain types of palpitation,
shortness of breath, a particular type of chest pain in the region of
the left breast (angina pectoris), swelling of the ankles and feet,
dizziness, fainting spells, extreme weariness, bluish lips, coughing up
of blood, or a persistent cough. A person suffering from such symptoms
should consult a doctor to determine whether heart disease is present.
After taking the patient’s medical history and making a thorough
examination, which may include an electrocardiogram, the doctor will
diagnose the condition and prescribe any treatment that may be required.
Palpitations
An unusually rapid, strong, or irregular heartbeat of which a person is
aware is called palpitation. In the majority of cases, palpitation is
completely normal; almost everyone, for example, feels his heart
pounding more rapidly and strongly after exertion or when he is excited
or nervous. Many people are also apt to be especially conscious of
heartbeat when they are lying in bed, especially when lying on the left
side. There are also palpitations that are abnormal but that do not of
themselves indicate heart disorder, though they may cause annoyance or
discomfort. Commonest is the “skipped beat”, or extrasystole; in some
cases this may occur because of excessive smoking o coffee drinking or
as a reaction to some kinds of medicine.
The various types of palpitation that may indicate heart disorder in
some instances include paroxysmal tachycardia and “flutter”, abnormal
rhythms in which the heart executes runs of rapid beats. Another is
auricular fibrillation, in which the beats are rapid but irregular,
seeming to occur at random.
These palpitations may be caused by organic heart disease, but they also
can result from other factors. Similarly, emotional pressures rather
than organic changes may cause the so-called “nervous heart”, or
functional heart disease. Although these symptoms do not prove
definitely that the heart is in a trouble, they should prompt a person
to consult his doctor. If the doctor’s examination shows no heart
disease, the individual can be reassured. If not, the doctor will be
able to begin immediate treatment.
Shortness of Breath
This may occur after only moderate exercise, such as climbing one flight
of steps. A person who finds himself continually in a breathless state
after activities which he once did without efforts should consult a
physician. Awakening at night short of breath may also be warning of
heart difficulties. This type of night breathlessness often takes the
form of feeling of suffocation or a choking sensation. Shortness of
breath may also indicate other disorders; some of these are described
more fully in the article on BREATHLESSNESS.
Chest Pain (Angina Pectoris)
This type of pain, usually over the heart or in the mid-chest, may
follow some excitement, a heavy meal, or exertion. It may not last more
than a minute or two, and may fade when the person rests or stands
still. Such pain may frequently be confused with similar symptoms
arising from gas pains or indigestion, but only a physician should
diagnose the complaint. Self-diagnosis can be dangerous.
Swelling of the Ankles and Feet
Deterioration of the heart’s pumping efficiency, or heart failure, can
throw the blood circulation odd balance and cause fluid to collect in
the tissues (edema). Swelling may be caused by varicose veins or by
standing for long periods of time, but puffiness of a different type
which may interfere with putting on shoes, or which can be deeply
indented by pressure with a finger, should be checked with a doctor.
Kinds of Heart Disease
The diseases affecting the heart and blood vessels range from defects
present at birth to damage of the organs caused by other diseases or
injuries. They include congenital, syphilitic, and rheumatic heart
disease; bacterial endocarditis, coronary insufficiency, coronary
thrombosis, heart failure, and related disorders.
Congenital Heart Defects
Between 30000 and 40000 children with one or more heart defects are born
annually in the USA. A quite common defect is the tetralogy of Fallot,
sometimes inaccurately called Blue Baby. Another defect consists of
passage between the aorta and pulmonary artery which normally closes
right after birth. There may be an opening between the ventricles, the
two pumping chambers of the heart (ventricular septal defect).
Defective valves affecting the flow of blood to and from the heart may
also be present.
A rarer congenital condition is transposition of the great vessels. In
this defect, the position of the chief blood vessels of the heart is
reversed. The aorta, the chief artery in the body, rises from the right
ventricle instead of the left, while the pulmonary artery, which carries
blood to the lungs, emerges from the left ventricle rather than from the
right. The result of this circulatory confusion is that dark oxygen-poor
blood returning from the body to the right side of the heart is pumped
back into the general circulation instead of being transported to the
lungs. Meanwhile, red, oxygen-rich blood flows aimlessly to and from the
lungs. Both the tetralogy of Fallot and the transposition of the great
vessels can be corrected in some instances by special surgery.
The condition in which the passage from the aorta to the pulmonary
artery fails to close after birth may occur by itself, without
associated defects. This defect forces the left ventricle to overwork.
Another congenital defect results when the foramen ovale, a window
between the auricles (upper chambers of the heart) fails to close
completely after birth. When an opening remains between the auricles,
some of the oxygen-rich blood from the left auricle passes into the
right auricle and travels back through the lungs without being first
transported through the body. Another heart defect, coarctation of the
aorta, results when the portion of the aorta is unusually narrow. In
many cases – depending on the severity of the defect and the physical
condition of the patient- these congenital conditions can be treated by
surgery.
Syphilitic Heart Disease
Years after syphilis is contracted, the disease can damage the aorta, as
well as injure the aortic valve. The walls of the aorta are invaded by
the syphilis germs, and eventually become weakened. The aorta gradually
dilates forming an ANEURYSM which may rupture.
Rheumatic Heart Disease
This disease most commonly starts between the age of 5 and 19 but can
occur at any age. It is the result of rheumatic fever, a combination of
a streptococcal infection and an allergic sensitivity to streptococcal
germs. It is responsible for most heart disease in individuals under the
age of 20.
Early indications of rheumatic fever may be a state of fatigue, poor
appetite, failure to gain weight, paleness, and anemia.
It is estimated that 50 percent of those who are diagnosed in adulthood
as having chronic rheumatic heart disease never realized they had
experienced attacks of rheumatic fever as children. The disease causes
an inflammation of the heart muscles and heart valves, and scars the
valves so that they do not perform normally. The damage may prevent the
valves from opening or closing properly. Rheumatic fever is controlled
by regular doses of penicillin and sulfa drugs, particularly in
adolescents and young adults.
Bacterial Endocarditis
This is a bacterial infection of the lining of the heart (endocardium)
and the valves which may follow rheumatic fever and also may occur in
persons with congenital defects of the heart. Bacteria, usually of the
streptococcus family, can enter the blood stream after operations on the
mouth, throat, nose, or intestines. If the microbes reach defective
heart valves, they can grow on them and cause a dangerous illness. That
is why persons with a history of rheumatic fever or those with
congenital heart abnormalities may be given penicillin or sulfa drugs
before undergoing certain operations or tooth extractions.
There are two forms of the disease, acute and subacute, with the
subacute form or more common. The acute type strikes the person suddenly
and can be fatal within a few days if immediate treatment is not given.
Treatment includes bed rest and antibiotics.
Coronary Insufficiency.
Coronary insufficiency is a term applied to heart difficulties in which
the blood flow in the coronary arteries which nourish the heart muscle
itself may be decreaced.Atherosclerosis ,a common form of hardening of
the arteries, may produce this condition by thickening or narrowing the
walls of the coronary arteries.When the arteries are narrowed, less
blood and less oxygen are carried to the heart musclemen.One form of
such insufficiency is ANGINA PECTORIS, in which the coronary arteries
temporarily do not provide the necessary blood to the heart muscle. The
amount of blood to the heart muscle may be adequate for periods of rest
or mild activity. Under conditions of emotional stress or increased
physical exertion, the supply may be insufficient for the added work of
the heart, and pain will result. The characteristic pain has been
described as crushing or viselike and located near the left breast. The
pain may fan out to the left arm and left fingers. Treatment consists of
rest, nitroglycerin tablets under the tongue, or inhalation of
amylnitrite.
Heart Failure
Heart failure does not mean that the heart has stopped, but that its
pumping efficiency has lessened. Two types of failure can interfere with
normal circulation. In one, circulatory, or forward, failure, the heart
is unable to pump enough oxygenated blood to the tissues because a
severe hemorrhage may cause the blood volume to fall, or because the
heart is not capable of supplying the tissues with sufficient blood.
In the second type of failure, known as cardiac insufficiency (
backward, or congestive, failure), the heart muscle loses its normal
vigorous beat and fails to propel the blood out of the heart chambers as
swiftly as it enters them. As a consequence of the slowing of
circulation, body fluids collect in the tissues. The ankles may swell,
and the individual may be short of breath because of fluid in the lungs.
There may be various types of indigestion from congestion of the liver
and other abdominal organs. This type of heart failure may develop after
a severe heart attack or rheumatic fever, after a long period of
untreated high blood pressure, or in connection with a congenital heart
defect.
In circulatory failure, the victim is pale and listless, and visible
veins sag. In cardiac insufficiency, the victim’s skin has a bluish
tinge, the jugular vein is swollen, and he breathes noisily. The
blueness stems from the fact that not enough oxygen is being supplied to
the arterial blood , and the tissues also lack sufficient oxygen, while
carbon dioxide mounts in the cells.
Treatment for heart failure includes rest, a special diet with lowered
salt intake, medication(digitalis) to strengthen heart action, and
diuretic medicines to control the excess of fluid.
Related Disorders
Hardening of the arteries and high blood pressure (hypertension) are two
of the most common forms of diseases affecting the heart, and are found
most frequently in the middle-aged or elderly person. The conditions may
be present separately, although they are frequently associated. In the
first, atherosclerosis, the walls of the arteries, and particularly the
internal lining called the intima, may become roughened. Fatty deposits
begin to collect. Fibrotic materials, and sometimes calcium, coat these
deposits, and help to form what are known as atherosclerotic plaques.
The damage spreads into the media, the muscular-elastic part of the
artery, and causes loss of resiliency. These plaques fill the
passageway, and gradually obstruct the flow of the blood. As the
arterial walls are narrowed, it becomes more difficult for the blood to
flow through the vessel.
Rise in blood pressure may be caused by a variety of factors, including
emotional stress. In 90 percent of the cases, the specific cause remains
undiscovered. It is believed that high blood pressure helps to speed the
processes of hardening of the arteries and other blood vessel diseases.
Hardening of the arteries and high blood pressure are chiefly
responsible for STROKES (Known as celebrovascular accidents), which are
caused by clogging or hemorrhaging of an artery in the brain or in an
artery in the neck leading to the brain. The walls of an artery may have
lost their smoothness and elasticity and collected the deposits typical
of hardening of the arteries, or the artery may have been clogged by a
blood clot from the heart. An area of the brain to which the blood
supply has been interrupted is injured, as a result of which some
muscular function controlled by the brain cells may be temporarily or
permanently lost.
Another disease related to diseases of the heart and blood vessels is
NEPHRITIS (Bright’s disease), or inflammation of the kidneys, which can
cause high blood pressure. The heart works under the high pressure
handicap, as in other types of hypertension. An acute attack of
nephritis may so injure the capillaries, the tiniest blood vessels, that
fluid settles in the tissues, causing swelling in various parts of the
body.
Prevention and Care
Guarding against heart ailments involves a reasonable consideration for
the amount of work the heart is accustomed to doing. For example, a man
over 40 should remember that a burst of unusual physical work or
strenuous sport creates a strain on a heart that is accustomed only to a
sedentary life. Extra weight places an extra burden on the heart. Fears
of heart trouble can also be harmful. It is wise to have regular medical
check-ups, and take intelligent care of one’s health, and to maintain a
sensible approach to life between examinations. This includes avoiding
excessive use of tobacco, following a well-balanced diet, taking regular
exercise, and maintaining a good balance between work, social life and
rest.
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