Heart

The heart is a muscular organ whose interior is divided into two pairs ofchambers, one on the right, the other on the left; the chambers of eachpair are connected with each other by a valve. Lying in the mid-leftsection 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 sturdymembrane called pericardium. Its chambers are lined by a delicate membrane,the endocardium, and its vigorous muscular and connective tissues arenourished 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 twocircuits, the pulmonary and the systemic. The right side of the heartreceives the blood from the large veins that drain the systemic circuit andpropels it into the lungs where carbon dioxide is removed and oxygen ispicked up. The oxygenated blood, collecting in the pulmonary veins, thanenters the left side of the heart, from which it is pumped out again intothe systemic circulation by way of the body's largest blood vessel, theaorta. The rhythmic pumping is in the form of a repeated contraction (systole) and relaxation (diastole). Every 60 seconds, this preciselyadjusted 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, theventricles. The auricle and ventricle on each side together form anindependent 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 forthe blood into the pulmonary circuit, the left into the general bodycircuit.

Valves of the heart

Between the right auricle and right ventricle is a valve, called thetricuspid valve. Similarly, the left auricle and left ventricle areconnected by the mitral valve, so named because of its apparent resemblanceto a bishop's miter or tall cap. The sounds of the valves opening andclosing are heard by the doctor when he listens with his stethoscope. Inaddition to the valves between auricle and ventricle on each side of theheart, there are valves at the blood's exit points: the pulmonary valveopening from the right ventricle into the pulmonary artery, and the aorticvalve 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 tokeep the blood flowing only in one direction through the heart's twoseparate pairs of chambers: from auricle to ventricle and out through itsappropriate artery.

A Single Pumping Action

Although the right and left sides of the heart serve two separate branchesof the circulation, each with its distinct function, they are co-ordinatedso that the heart efficiently serves both sides with a single pumpingaction. The valve action on both sides is also co-ordinated with the twophases of the pumping action. Thus, during the diastole, or relaxationphase, the oxygen-poor blood which was accumulated in the right auriclereturning from the systemic or body circulation pours into the rightventricle. At the same time, the oxygen-rich blood which was accumulated inthe left auriclereturning from the pulmonary circulation pours into theleft ventricle. The weak walls of both auricles contract to press the bloodinto the relaxed ventricles. In the next or contraction phase, the systole,the valve between auricle and ventricle on each side closes, and themuscular walls contract the ventricles and sweep the blood through eachpassage into the pulmonary artery and the aorta. At the end of thecontraction the pulmonary and aortic valves snap shut, preventing anybackward surge of the blood to the ventricles. The diastole follows, theventricles again fill with the flow from their separate auricles and thecycle is repeated. This co-ordinated rhythmic action goes on tirelessly dayand night throughout every individual's lifetime.

The Valve Cusps

The valves, which must withstand considerable pressure, are composed of aspecial type of tough tissue. The mitral valve, between the left auricleand ventricle, has two cusps or leaflets. The tricuspid valve, between theright auricle and ventricle, has three cusps. Both valves function in thesame manner. When blood pressure in auricle is higher than in theventricle, the valve leaflets are swept open; as the blood flows downward,the auricular contraction at the start of the heart beat helps to push theblood along. As the blood fills the ventricle, the leaflets close, and withthe contraction of the ventricle, pressure tightly shuts the valve. Thevalve leaflets are bolstered from below by a set of tough tendons withmuscular attachments, enabling the leaflets to withstand the pressure andkeep the valves from opening inward into the auricle.
The two valves which control the exit passages from the heart, the aorticvalve and the pulmonary valve, have three leaflets each, and they also onlyfor one-way flow. Other valves at special stations along the line in thecirculatory system keep the blood from pooling in the lower extremities ofthe body.
Heart Disease.
Heart disease, the leading cause of death, is a term covering a variety ofmore than 20 different diseases of the heart and blood vessels. The mostcommon of these are rheumatic heart disease, hypertension or high bloodpressure, and coronary artery disease. Other forms of heart disease can becaused by congenital malformations of the heart and major vessels,syphilis, diphtheria, abnormal functioning of the thyroid gland, ordiseases resulting from vitamin deficiencies.
Although approximately ten million Americans have some form of heartdisease, the tremendous advances made by medical science have made itpossible to treat and control these illnesses with increasing success. Themajority of individuals who suffer a heart attack recover, and recurrentattacks of rheumatic fever which injure the heart can now frequently beprevented. By means of modern surgical techniques, heart defects and heartdamage may often be repaired by HEART SURGERY.
To clarify various descriptions of heart ailments, it should be understoodthat a "heart attack" is not strictly the same as "heart disease". A heartattack usually signifies the sudden obstruction of a coronary artery, oneof the blood vessels feeding blood to the heart muscle; the clogging of theartery by a blood clot cuts off the blood supply to an area of the heartmuscle. There is also a distinction between a heart attack, heart disease,and "heart failure". Heart failure does not mean that the heart has stoppedbeating but that the heart is not pumping efficiently and the body's bloodcirculation is being affected by the change.
One of the most prevalent of the diseases involving the heart isarteriosclerosis, commonly known as hardening of the arteries. Diseases ofother organs of the body can also produce heart disease; one of these isnephritis, a disease of the kidneys which affects the tiny blood vessels orcapillaries. Another such disease is diabetes which in some individuals mayinjure the blood vessels in much the same fashion as does high bloodpressure.

Symptoms

Symptoms of heart disease may include certain types of palpitation,shortness of breath, a particular type of chest pain in the region of theleft breast (angina pectoris), swelling of the ankles and feet, dizziness,fainting spells, extreme weariness, bluish lips, coughing up of blood, or apersistent cough. A person suffering from such symptoms should consult adoctor to determine whether heart disease is present. After taking thepatient's medical history and making a thorough examination, which mayinclude an electrocardiogram, the doctor will diagnose the condition andprescribe any treatment that may be required.
Palpitations
An unusually rapid, strong, or irregular heartbeat of which a person isaware is called palpitation. In the majority of cases, palpitation iscompletely normal; almost everyone, for example, feels his heart poundingmore rapidly and strongly after exertion or when he is excited or nervous.
Many people are also apt to be especially conscious of heartbeat when theyare lying in bed, especially when lying on the left side. There are alsopalpitations that are abnormal but that do not of themselves indicate heartdisorder, though they may cause annoyance or discomfort. Commonest is the
"Skipped beat", or extrasystole; in some cases this may occur because ofexcessive smoking o coffee drinking or as a reaction to some kinds ofmedicine.
The various types of palpitation that may indicate heart disorder in someinstances include paroxysmal tachycardia and "flutter", abnormal rhythms inwhich the heart executes runs of rapid beats. Another is auricularfibrillation, in which the beats are rapid but irregular, seeming to occurat random.
These palpitations may be caused by organic heart disease, but they alsocan result from other factors. Similarly, emotional pressures rather thanorganic changes may cause the so-called "nervous heart", or functionalheart disease. Although these symptoms do not prove definitely that theheart 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 bereassured. 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 ofsteps. A person who finds himself continually in a breathless state afteractivities which he once did without efforts should consult a physician.
Awakening at night short of breath may also be warning of heartdifficulties. This type of night breathlessness often takes the form offeeling of suffocation or a choking sensation. Shortness of breath may alsoindicate other disorders; some of these are described more fully in thearticle on BREATHLESSNESS.
Chest Pain (Angina Pectoris)
This type of pain, usually over the heart or in the mid-chest, may followsome excitement, a heavy meal, or exertion. It may not last more than aminute or two, and may fade when the person rests or stands still. Suchpain may frequently be confused with similar symptoms arising from gaspains 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, canthrow the blood circulation odd balance and cause fluid to collect in thetissues (edema). Swelling may be caused by varicose veins or by standingfor long periods of time, but puffiness of a different type which mayinterfere with putting on shoes, or which can be deeply indented bypressure with a finger, should be checked with a doctor.

Kinds of Heart Disease

The diseases affecting the heart and blood vessels range from defectspresent at birth to damage of the organs caused by other diseases orinjuries. They include congenital, syphilitic, and rheumatic heart disease;bacterial endocarditis, coronary insufficiency, coronary thrombosis, heartfailure, and related disorders.

Congenital Heart Defects

Between 30000 and 40000 children with one or more heart defects are bornannually in the USA. A quite common defect is the tetralogy of Fallot,sometimes inaccurately called Blue Baby. Another defect consists of passagebetween the aorta and pulmonary artery which normally closes right afterbirth. There may be an opening between the ventricles, the two pumpingchambers of the heart (ventricular septal defect). Defective valvesaffecting the flow of blood to and from the heart may also be present.
A rarer congenital condition is transposition of the great vessels. In thisdefect, the position of the chief blood vessels of the heart is reversed.
The aorta, the chief artery in the body, rises from the right ventricleinstead of the left, while the pulmonary artery, which carries blood to thelungs, emerges from the left ventricle rather than from the right. Theresult of this circulatory confusion is that dark oxygen-poor bloodreturning from the body to the right side of the heart is pumped back intothe 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 canbe corrected in some instances by special surgery.
The condition in which the passage from the aorta to the pulmonary arteryfails to close after birth may occur by itself, without associated defects.
This defect forces the left ventricle to overwork. Another congenitaldefect results when the foramen ovale, a window between the auricles (upperchambers of the heart) fails to close completely after birth. When anopening remains between the auricles, some of the oxygen-rich blood fromthe left auricle passes into the right auricle and travels back through thelungs without being first transported through the body. Another heartdefect, coarctation of the aorta, results when the portion of the aorta isunusually narrow. In many cases - depending on the severity of the defectand the physical condition of the patient-these congenital conditions canbe treated by surgery.

Syphilitic Heart Disease

Years after syphilis is contracted, the disease can damage the aorta, aswell as injure the aortic valve. The walls of the aorta are invaded by thesyphilis germs, and eventually become weakened. The aorta gradually dilatesforming an ANEURYSM which may rupture.

Rheumatic Heart Disease

This disease most commonly starts between the age of 5 and 19 but can occurat any age. It is the result of rheumatic fever, a combination of astreptococcal 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, poorappetite, failure to gain weight, paleness, and anemia.
It is estimated that 50 percent of those who are diagnosed in adulthood ashaving chronic rheumatic heart disease never realized they had experiencedattacks of rheumatic fever as children. The disease causes an inflammationof the heart muscles and heart valves, and scars the valves so that they donot perform normally. The damage may prevent the valves from opening orclosing properly. Rheumatic fever is controlled by regular doses ofpenicillin and sulfa drugs, particularly in adolescents and young adults.

Bacterial Endocarditis

This is a bacterial infection of the lining of the heart (endocardium) andthe valves which may follow rheumatic fever and also may occur in personswith congenital defects of the heart. Bacteria, usually of thestreptococcus family, can enter the blood stream after operations on themouth, throat, nose, or intestines. If the microbes reach defective heartvalves, they can grow on them and cause a dangerous illness. That is whypersons with a history of rheumatic fever or those with congenital heartabnormalities may be given penicillin or sulfa drugs before undergoingcertain operations or tooth extractions.
There are two forms of the disease, acute and subacute, with the subacuteform or more common. The acute type strikes the person suddenly and can befatal within a few days if immediate treatment is not given. Treatmentincludes bed rest and antibiotics.
Coronary Insufficiency.
Coronary insufficiency is a term applied to heart difficulties in which theblood flow in the coronary arteries which nourish the heart muscle itselfmay be decreaced.Atherosclerosis, a common form of hardening of thearteries, may produce this condition by thickening or narrowing the wallsof the coronary arteries.When the arteries are narrowed, less blood andless oxygen are carried to the heart musclemen.One form of suchinsufficiency is ANGINA PECTORIS, in which the coronary arteriestemporarily do not provide the necessary blood to the heart muscle. Theamount of blood to the heart muscle may be adequate for periods of rest ormild activity. Under conditions of emotional stress or increased physicalexertion, the supply may be insufficient for the added work of the heart,and pain will result. The characteristic pain has been described ascrushing or viselike and located near the left breast. The pain may fan outto the left arm and left fingers. Treatment consists of rest, nitroglycerintablets under the tongue, or inhalation of amylnitrite.

Heart Failure

Heart failure does not mean that the heart has stopped, but that itspumping efficiency has lessened. Two types of failure can interfere withnormal circulation. In one, circulatory, or forward, failure, the heart isunable to pump enough oxygenated blood to the tissues because a severehemorrhage may cause the blood volume to fall, or because the heart is notcapable 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 beatand fails to propel the blood out of the heart chambers as swiftly as itenters them. As a consequence of the slowing of circulation, body fluidscollect in the tissues. The ankles may swell, and the individual may beshort of breath because of fluid in the lungs. There may be various typesof indigestion from congestion of the liver and other abdominal organs.
This type of heart failure may develop after a severe heart attack orrheumatic fever, after a long period of untreated high blood pressure, orin connection with a congenital heart defect.
In circulatory failure, the victim is pale and listless, and visible veinssag. In cardiac insufficiency, the victim's skin has a bluish tinge, thejugular vein is swollen, and he breathes noisily. The blueness stems fromthe fact that not enough oxygen is being supplied to the arterial blood,and the tissues also lack sufficient oxygen, while carbon dioxide mounts inthe cells.
Treatment for heart failure includes rest, a special diet with lowered saltintake, medication (digitalis) to strengthen heart action, and diureticmedicines to control the excess of fluid.

Related Disorders

Hardening of the arteries and high blood pressure (hypertension) are two ofthe most common forms of diseases affecting the heart, and are found mostfrequently in the middle-aged or elderly person. The conditions may bepresent separately, although they are frequently associated. In the first,atherosclerosis, the walls of the arteries, and particularly the internallining called the intima, may become roughened. Fatty deposits begin tocollect. Fibrotic materials, and sometimes calcium, coat these deposits,and help to form what are known as atherosclerotic plaques. The damagespreads into the media, the muscular-elastic part of the artery, and causesloss of resiliency. These plaques fill the passageway, and graduallyobstruct the flow of the blood. As the arterial walls are narrowed, itbecomes more difficult for the blood to flow through the vessel.
Rise in blood pressure may be caused by a variety of factors, includingemotional stress. In 90 percent of the cases, the specific cause remainsundiscovered. It is believed that high blood pressure helps to speed theprocesses of hardening of the arteries and other blood vessel diseases.
Hardening of the arteries and high blood pressure are chiefly responsiblefor STROKES (Known as celebrovascular accidents), which are caused byclogging or hemorrhaging of an artery in the brain or in an artery in theneck leading to the brain. The walls of an artery may have lost theirsmoothness and elasticity and collected the deposits typical of hardeningof the arteries, or the artery may have been clogged by a blood clot fromthe heart. An area of the brain to which the blood supply has beeninterrupted is injured, as a result of which some muscular functioncontrolled 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 cancause high blood pressure. The heart works under the high pressurehandicap, as in other types of hypertension. An acute attack of nephritismay so injure the capillaries, the tiniest blood vessels, that fluidsettles in the tissues, causing swelling in various parts of the body.

Prevention and Care

Guarding against heart ailments involves a reasonable consideration for theamount of work the heart is accustomed to doing. For example, a man over 40should remember that a burst of unusual physical work or strenuous sportcreates 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 troublecan also be harmful. It is wise to have regular medical check-ups, and takeintelligent care of one's health, and to maintain a sensible approach tolife between examinations. This includes avoiding excessive use of tobacco,following a well-balanced diet, taking regular exercise, and maintaining agood balance between work, social life and rest.

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