cardiovascular system disease China medical university pediatrics Xianyi yu
1. Anatomic and physiologic characteristics of cardiovascular system in children
(1) Embryo heart development Primary heart is formed during embryo 2-8 weeks. 4th weeks: heart beats appear single vesculum 8th weeks: 4 caves
placenta umbilical vein liver inferior vena cava RA foramen ovale LA
LV
AO
heart,brain,arms
SVC RA RV PA DA dAO abdomen,legs umbilical artery placenta
(3) Circulatory changes after birth foramen ovale closure closure functionally within the first few minutes after birth closure anatomically after about 6 months ductus arteriosus closure closure functionally within the first 10-15 hours of life closure anatomically after 3-4 months
(4) cardiac size and position < 2 years horizontal position, cardiac apex left border at IV intercostal space 1-2 cm out of midclavicular line >2years slanting position, 6 years, V intercostal space on the midclavicular line
(5) heart rate
• • • • •
The younger, the faster Age Heart rate Newborn 120-140 beats/min Infant 110-130beats/min 2-3years 100-120 beats/min Preschool 80-100 beats/min School age 70-90 beats/min
(6) Blood pressure Blood pressure increases gradually with advancing age Systolic pressure = age × 2 + 80 mmHg Diastolic pressure = 2/3 systolic pressure in mature infant 75/50 mmHg
2. Congenital heart diseases (CHD) (1) Definition cardiac or great blood vessel malformation occurred during embryo. (2) Incidence of CHD 7-8 ‰ ( per 1000 alive birth ) If they have no medical care, 50% die. CHD is important reason of death in infants although treated.
(3) Etiology enviromental factors virus infection: rubella, cytomegalo-virus, herpes virus coxsackie-virus drugs: anticonvulsant agents, cortison anticarcinogen radiation: contact metabolic diseases: diabetes, hypercalcemia
Genetic factors: chromosomal abnormality: 20% trisomy- 21 complicated with CHD proband 18-22 ‰
(4) Classification of CHD CHD with cyanosis (dominant right to left shunt) Tetralogy of Fallot, Eisenmenger syndromes, Transposition of great arteries CHD with little cyanosis (dominant left to right shunt) Ventricular septal defect, Atrial septal defect, Patent ductus arteriosus
CHD with acyanosis ( no shunt) Pulmonic stenosis, coarctation of aorta
(5) Diagnosis of CHD history age < 3years maternal history : the first 3 months during pregnancy
common symptoms: feeding difficulty interrupt suck tachypnea cyanosis hoarseness perspiration fatigability respiratory tract infection frequently slow growth
physical findings generality: poor development cyanosis clubbing of the fingers and toes other malformations
heart examination: • inspection: protrusion of precardium apex beat extension • palpation: systolic thrill at left sternal border • percussion: cardiac borders extension • auscultation: murmur ( place, loudness, nature, period, distribution) second heart sound ( accent, weaken, disappear, split)
other examinations X-ray: cardiac size, shape cardiothoracic radio, lungs field ECG: ventricular and atrial size Echo: cardiac caves size, construction, turbulent by Doppler Catheterization: pressure and oxygen content, abnormal passage, injection of contrast material for ventriculography
Ventricular septal defect ( VSD)
VSD is the most common CHD, account for 25-50% 1. Anatomy 1) membranous defect: 70-80% 2) muscular defect: smaller single or multiple diameter: small < 0.5 cm middle 0.5-1.0 cm large > 1.0 cm
2. Hemodynamics 1) left right shunt LV pressure (80-130/5-10mmHg) RV pressure (15-30/2-5mmHg) LVP > RVP 2) pulmonary hypertension L R shunt pulmonary congestion hypertension dynamic pulmonary hypertension obstructive pulmonary hypertension
Eisenmenger syndrome: severe hypertension pulmonary resistance exceed systemic R to L shunt cyanosis (3) LV hypertrophy blood returning to LA, LV increase LV overload (4) systemic circulation insufficient L R shunt
