Anatomic Physiologic features cardiovascular system in infants and children. associate professor Kantemirova M.G.

Fetal circulation

Postnatal circulation

The critical period for prenatal development of cardio-vascular system is since the end of 2d weeks to 7-8 th weeks. Teratogenic factors affect the embryon at this period – results in congenital heart diseases

The features of fetal and postnatal circulation The presence of low resistance and high velocity placental circulation which provides the gas exchange for the fetus The absence of gas exchange in the lungs ( it results in very small blood flow through the lungs and consequently in small pulmonary venous return to the left atrium The presence of ductus venosus - low resistance bypass between umbilical vein and v.cava inferior

The features of fetal and postnatal circulation The connection between the right and left parts of the heart and great vessels (the functioning of the two right-left shunt): - blood flow through the foramen ovale between the right and left atrias - blood flow through the ductus arteriosus between the pulmonary artery and aorta Ductus venosus, ductus arteriosus, foramen ovale – fetal vascular communications

The features of fetal and postnatal circulation Admission to the most vital organs (brain, heart, liver), more oxygenated blood (pO2 – mmHg; stO2 – 65% - v.cava superior: pO mmHg; stO2-40%) The left ventricular output is one-third of the combined left-right ventricular output Almost simultaneous and parallel contuction of the right and left ventricles

The features of fetal and postnatal circulation A slight predominance of right atrial pressure above the left A significant excess of minute volume of the systemic circulation over a minute volume of pulmonary circulation (pulmonary blood flow % of the total cardiac output) due to shunts The same low pressure in the pulmonary artery and aorta (70/45 mmHg)

Major changes in blood circulation in newborns Cessation of placental circulation Closure of fetal communications The right and left ventricules contraction in series (instead of in parallel) Start the full functioning of the pulmonary circulation with high resistance and a tendency to vasoconstriction The increase in oxygen demand, increased cardiac output and systemic vascular resistance

Anatomical closure of foramen ovale – months; 50% - 5 years Anatomical closure of ductus arteriosus – 2 months

Features of cardiovascular system in infants Mass of the heart is 0.8% of body weight (adult 0.5%) The right and left ventricle are equal, the thickness is 5 mm; to years left ventricule wall thickness is mm. The growth of the left ventricle more prominent than the right ventricle. The relatively large size of the atria and great vessels than at other age periods Periods of intensive growth of the mass of the heart: 0-2 years, years, years Muscle fibers are very thin, little demarcated from each other, contain a nucleus, contractile myofibrils less than the elastic fibers Abundant blood supply to the heart

Features of cardiovascular system in infants The development of histological structures of conductive system finishs to 14 years Up to 3-4 years the regulation of cardiac activity carried out mainly by the sympathetic nervous system (physiological tachycardia in children), complete mielinization of the vagus nerve at the age 3-4 years The wide lumen of blood vessels (arteries and veins are equal in diameter), with age the arteries become narrower

Features of cardiovascular system in infants Pulmonary artery till 10 years greater than aortic lumen; at the age of years it is equal, and the lumen of the aorta is wider than LA in puberty Blood vessels are thin, with underdeveloped muscle and elastic fibers The muscular layer of the pulmonary arterioles intima is hypertrophic and hyperplastic; during the first months of life there is its involution with thinning of the walls and an increase in lumen

Heart rate AgeHeart rate Newborn 1 year 3 years 5 years 8 years 10 years 12 years

Границы относительной сердечной тупости при перкуссии Граница0-1 год2-6 лет7-12 лет Верхняя граница Второе реброВторое межреберье Третье ребро Левая граница1-2 см кнаружи от левой среднеключичной линии По левой средне- ключичной линии Правая границаПравая парастерналь- ная линия Кнутри от правой парастерналь ной линии Середина расстояния между правой парастернальной линией и правым краем грудины Поперечник области притупления 6 – 98 – 129 – 14

Chest x-ray: а — newborn; б — 3 years old child в —11 years child

Blood pressure Systolic BP in newborns - 66 – 76 ммHg; 1 year 90 – 100 мм.рт.ст BP systolic = n (n – years of age) BP dyastolic = 60 + n (n – years of age) The sum of heart rate and systolic blood pressure values ​​ in all periods of childhood is about 200.

Артериальное давление Величина артериального давления у детей и подростков зависит от возраста, пола, массы тела и роста. Диагностика артериальной гипертензии проводится с использованием специальных таблиц, основанных на популяционных исследованиях, и состоит из следующих этапов: определение по специальным таблицам процентилей роста, соответствующего полу и возрасту пациента вычисление средних значений САД и ДАД на основании трех измерений АД, проведенных с интервалом 2-3 мин сопоставление средних значений САД и ДАД пациента, полученных по результатам 3-х кратного измерения АД на одном визите, с 90 и 95 процентилями АД, соответствующими полу, возрасту и процентилю роста пациента сравнение средних значений САД и ДАД, зарегистрированных у пациента на трех визитах с интервалом между ними дней, с 90 и 95 процентилями АД, соответствующими полу, возрасту и процентилю роста пациента

Критерии нормального, высокого нормального АД и артериальной гипертензии Нормальное АД – средние уровни САД и ДАД на трех визитах, меньшие значений 90 процентиля для данного возраста, пола и роста Высокое нормальное АД – средние уровни САД и ДАД на трех визитах, равные или превышающие значения 90 процентиля, но меньшие значений 95 процентиля для данного возраста, пола и роста Артериальная гипертензия – средние уровни САД и ДАД на трех визитах, равные или превышающие значения 95 процентиля для данного возраста, пола и роста.

Pathological x-ray

Fibroelastosis of endomyocardium Nonrheumatic postnatal carditis

Dilated cardiomyopathy ASD

ECG - pericarditis

Миоперикардит