VALVULAR LESION Anatomy.—Slight grades of cardiac hypertrophy in children are only discovered with difficulty, even in examination of the cadaver, since the size, weight and thickness of the walls of the heart vary in the different years of life. Precise anatomic diagnoses are only obtained by weighing and measuring, and comparing results with the figures given for these relations by Muller, Beneke and Bizot (see page 451). As regards histology, attention should be paid to the size of the fibres of the heart muscle, which are 4 or 5 times larger in adults, and to their greater slenderness in early childhood. E. Weill found a striking in crease of the fihrillie of the heart muscle with cardiac hypertrophy of renal origin in children.
As in adults, simple and eccentric, general and partial (right-sided or left-sided) hypertrophy are also differentiated in children. In left sided hypertrophy the heart. is enlarged downward and to the left, be coming cylindro-conic in form; in right-sided hypertrophy the heart forms the segment of a bow, due to increase in its horizontal diameter, with the string of the bow outlined by the left ventricle.
Cardiac hypertrophy as the result of angiosclerotic processes is rare in childhood ancl is always due to syphilis. As a rule hypertrophy and dilatation of the child's heart are conditions resulting from other diseases occurring inside or outside of the heart.
Etiology. —Congenital hypertrophy is infrequent without other cardiac diseases; in the first months of life acquired hypertrophy occurs, always associated with enlargement of the thymus gland, from Hoch singer's radiographic observations (Fig. 101). Though hypertrophy of the right side of the heart may exist for some time after birth, often as ((Mal remains, hypertrophy of the left side of the heart, occurring be tween the third and fourth years of life, depends upon isthmus forma tion in the aorta which has not been completed early in all children (Gerhardt).
Eccentric hypertrophy of the heart may occur during whooping cough and chronic bronchopneumonia; also with shrinking of the lungs and bronchiectasis. High-grade tickets may also have this effect on the heart, as the result of compression of the thorax and the pulmonary circulation. Very important among the causes of cardiac hypertrophy in children are renal affections. Deformities of the thorax (kyphosco
hosis), overexertion of the heart and the infectious diseases may also produce cardiac hypertrophy.
Germain See has considered an idiopathic hypertrophy of the heart due to growth at the age of puberty, which he explained as an inde pendent overdevelopment of the heart as compared with the regular growth of the body. This view has been opposed by numerous writers, especially Potain and (filivier.
According to E. Smith, moderate grades of cardiac dilatation occur very frequently in ancemic children who have grown rapidly, with chronic pulmonary affections, especially with bronchopneumonia. Hauser noted cor liovinum with enormous dilatation of the heart and signs of chronic congestion in a child of eleven months, who died of whooping-cough, without any change in the valvular apparatus.
Alone stand the t WO CaSOS of high-grade congenital idiopathic hypertrophy of the heart, described by Raissa Efron in infants of six months and one year, produced by compression of the left bronchus. Autop.sy in both cases showed a very large heart, hypertrophied equally in all its parts, without the slightest changes in the valves or ostia.
Symptoms.—A violent shaking in the precordial region, with for ward arching of the precordium, downward displacement of the apex beat, long,ituffinal increase in the cardiac dulness with hypertrophy of the left side of the heart, horizontal increase in the dulness when this hypertrophy is right-sided, and accelerated heart action are the essen tial symptoms of cardiac hypertrophy.
The cardiac impulse and the heart sounds are both weakened in dilatation of the heart. With dilatation of the right side of the heart are noted dilated veins, peripheral cyanosis and relative tricuspid insufficiency also; with left-sided dilatation, dilatation insufficiency of the mitral valve occurs, accompanied by a dull systolic murmur at the apex. Dila tation of the heart may- be permanent or transitory, and is always a sign of weakness of the cardiac muscle. The appearance of dilatation of the heart in acute or chronic nephritis, whooping-cough or bronchopneu monia in children is always unfavorable.