HEART 



3898 



HEART 



aorta or main blood-vessel, through 

 which blood is distributed all over 

 the body, the orifice being guarded 

 by three semilunar valves. 



"The muscular substance of the 

 heart is nourished by the two coron- 

 ary arteries, which spring from the 

 root of the aorta and pursue a 

 course mainly between the cham- 

 bers of the heart. The heart goes 

 through a series of contractions and 

 relaxations, producing the familiar 

 heart beat, the contraction being 

 known as systole, the relaxation 

 as diastole. The contraction does 

 not, however, affect the whole heart 

 at once ; it occurs first in the two 

 auricles together and immediately 

 afterwards in the two ventricles. 

 Rate of Heart Beat 



After a short pause, the auricles 

 again contract, and then the ven- 

 tricles, the whole process thus 

 forming a cycle of changes. In a 

 healthy adult, the heart beats on 

 the average 72 times in a minute. 

 Apart from disease, the rate of the 

 heart beat is increased by exercise 

 and emotion and slowed by mental 

 or bodily rest. Before birth, the 

 average rate of the heart beat is 

 150 per minute, and during the 

 first year of life from 115 to 130. 

 The rate gradually decreases as age 

 progresses, and in old age the pul- 

 sations are between 60 and 70. 



When the heart is examined by 

 means of the stethoscope, or the 

 ear is placed to the front of the 

 chest, two sounds are heard, fol- 

 lowed by a short pause. The first 

 sound, which is prolonged, is mainly 

 due to the closing of the mitral 

 and tricuspid valves. The second 

 sound is shorter and sharper, and is 

 mainly produced by the closing of 

 the aorta and pulmonary valves. 

 Variations in the sounds of the heart 

 constitute a valuable means for 

 diagnosing disorders and diseases of 

 the heart. In a healthy person, the 

 beat of the apex of the heart can 

 be felt on the surface in the space 

 between the 5th and 6th ribs and 

 about one inch inside a vertical 

 line drawn through the nipple. 



DISEASES OF THE HEART. De- 

 fects in the heart may be present 

 at birth, congenital, as they are 

 called. The symptoms usually 

 appear within the first weeks of 

 life. Cyanosis or lividity of the 

 skin, which may be most marked 

 in the lips, nose, ears, fingers, and 

 toes, is nearly always present. 

 Difficulty in breathing and cough 

 are frequent symptoms. If the 

 defect is serious, the child gener- 

 ally dies within a lew months. The 

 following are the main forms of 

 acquired disease of the heart : 



Endocarditis, or inflammation 

 of the lining membrane of the 

 heart, usually affects the valves. 



Acute simple endocarditis occurs as 

 a complication of another disease, 

 most frequently rheumatic fever, 

 and sometimes tonsillitis and scar- 

 let fever. In rare instances it is 

 associated with measles or diph- 

 theria, and it may also complicate 

 pneumonia and phthisis. Malignant 

 endocarditis is a severe form in 

 which ulceration of the heart 

 valves occurs. The disease is due 

 to infection by a micro-organism. 

 In mild cases the symptoms may 

 not be very marked, but in what 

 are known as the septic and ty- 

 phoid types there may be severe 

 prostration, delirium, and coma, 

 with fatal termination. Sometimes 

 the acute symptoms subside and 

 the disease becomes chronic. The 

 most important factor in the treat- 

 ment is prolonged rest in bed. 



Any valve of the heart may be 

 affected by disease, but the mitral 

 and aortic valves are those most 

 frequently involved. The valve 

 may not close properly (incom- 

 petency), with the result that the 

 blood flows back into the chamber 

 from which it has just passed ; or 

 the valve may be permanently 

 narrowed (stenosis), so that the 

 passage of blood trom one cham- 

 ber to another is impeded. 

 Forms of Incompetency 



In aortic incompetency the aor- 

 tic valves do not close properly, 

 and some of the blood from the 

 left ventricle, instead of passing 

 on into the aorta, flows back into 

 the ventricle. The most frequent 

 cause is slow thickening of the edges 

 of the valve, associated with a more 

 or less general thickening of the 

 walls of the arteries throughout the 

 body. This condition is frequently 

 due to alcoholism or syphilis, espe- 

 cially in those whose occupation 

 involves prolonged muscular effort. 

 Other causes are endocarditis and 

 congenital defects. The early symp- 

 toms are headache, dizziness, and 

 feelings of faintness on rising 

 abruptly, palpitation, and pain in 

 the chest. As the condition pro- 

 gresses, the patient suffers from 

 shortness of breath, and there may 

 be some dropsy of the feet. Sudden 

 death may occur. In severe cases 

 the heart becomes enlarged, and 

 may weigh as much as 40 ounces. 



Aortic stenosis is a narrowing of 

 the aortic opening, resulting from 

 thickening of the aortic valves and 

 adhesion one to another. It is less 

 frequent than aortic incompetency. 

 Pain, dizziness, and fainting are the 

 early symptoms. As the disease 

 progresses, the mitral valve also 

 becomes affected, and general 

 dropsy may be present. 



Mitral incompetency is most 

 often due to endocarditis. It may, 

 however, be associated with cal- 



careous changes in the valve. The 

 blood from the left ventricle tends 

 to flow back into the auricle. This 

 leads to dilatation of the auricle, 

 which is followed by dilatation of 

 the ventricle, and later the in- 

 creased pressure produces dilata- 

 tion of the pulmonary vessels, 

 with changes in the lungs. Early 

 symptoms are a bluish tint of the 

 lips and face, and shortness of 

 breath on exertion. In a later stage 

 there is palpitation, difficulty in 

 breathing, and the action of the 

 heart becomes irregular. A cough 

 occurs owing to the disturbance of 

 the pulmonary circulation. Dropsy, 

 beginning in the feet, later ex- 

 tends to the legs, and there may be 

 accumulation of fluid within the 

 abdomen. Death occurs from 

 general dropsy or from heart fail- 

 ure following repeated attacks. 

 Sudden death is infrequent. 



Mitral stenosis is usually the re- 

 sult of endocarditis. The" passage 

 of blood from the auricle to the 

 ventricle is impeded, and this 

 leads to thickening of the wall of 

 the auricle. The condition is always 

 associated with some degree of in- 

 competency of the valves as well. 

 A person may be unaware of 

 the existence of the disease for 

 years, but when the compensatory 

 changes in the heart break down 

 the patient suffers from shortness 

 of breath, cough, and irregular ac- 

 tion of the heart. Affections of the 

 tricuspid valve are generally secon- 

 dary to changes in the other valves 

 of the heart. Affections of the pul- 

 monary valves are rare. Not in- 

 frequently two or more valves are 

 affected simultaneously, and in- 

 competency and stenosis may 

 occur together. 



Adjustment and Compensation 



The heart possesses very con- 

 siderable power of adjusting itself 

 to affections of the valves. In both 

 stenosis and incompetency, the 

 muscular wall of the heart thickens, 

 and the force of contraction is in- 

 creased so as to ensure that the 

 same amount of blood is driven 

 into circulation. This condition is 

 known as compensation, and so 

 long as compensation is effective 

 no treatment is required. 



When compensation fails, and 

 symptoms such as shortness of 

 breath or fainting occur, treat- 

 ment must be given. Rest in bed 

 is of great importance, as it re- 

 lieves the heart of an appreciable 

 amount of its work, and enables 

 the muscle slowly to develop suffi- 

 cient power to overcome the defect. 

 The heart may also be relieved 

 when the circulation becomes 

 embarrassed by diminishing the 

 amount of fluid in the body, which 

 may be done by the administration 



