10. 1. Fetal circulation and circulatory changes after birth Special structures in the fetal CVS A patent foramen ovale A patent ductus arteriosus A ductus venosus The placenta
11. The placenta (nourishing the developing fetus) and the umbilcal cord (connecting a fetus with the placenta of mother)
13. The process of the fetal circulation: Oxygenated blood (placenta ) Liver Inferior vena cava Right atrium Left atrium Left ventricle Ascending aorta Upper part of the body Deoxygenated blood(upper part) Superior vena cava Right ventricle Puomonary artery Descending aorta Lower part of the body Lung Foramen ovale Righ atrium Ductus ateriosus Placenta Ductus venosus
14. Right-left blood shunts through the foramen ovale and ductus arteriousus occur because of the higher pulmonic resistance and lower systemic resistance Two ventricles work in parallel rather than in series The concentration of oxygen is highest in the liver, next is the upper part of the body and the last is the lower part of the body. Distinct features of the fetal circulation:
15. The changes of circulation after birth Establishment of pulmonary circulation Cessation of the umbilicus-placenta circulation Systemic resistance > pulmonic resistance Right-left blood shunt through the foramen ovale is limited and eventually eliminated, the foramen ovale anatomically closes within 5-7m after birth. Blood shunt through the ductus arteriosus is reduced. Higher oxygen content of the blood and loss of prostaglandins leads to gradual closure of the ductus arteriosus Functional closure within 10-15hs after birth and anatomically within 3m (80%)-1y(95%).
16. 2. Heart rate The younger the child is , the faster the heart rate is. Age Heart rate Neonate 120-140/min Infancy 110-130/min Preschool age 80-100/min School age 70-90/min
17. 3. Blood pressure Arterial pressure gradually increases with advancing age. A mature infant averages 10/6.67kPa(75/50mmHg) (1mmHg 0.133kPa, 1kPa 7.5mmHg) The formula for older children(>2y): Systolic pressure=age ×2+80mmHg Diastolic pressure=2/3 systolic pressure Hypertension: Systolic pressure is 20mmHg higher than the normal value Hypotension: Systolic pressure is 20mmHg lower than the normal value The blood pressure in the lower limbs is 20mmHg higher than that in the upper limbs
18. Congenital Heart Diseases (CHD) Diagnostic Techniques for CHD VSD Tetralogy of Fallot ASD PDA Introduction of CHD
28. History taking Pregnant history of the mother: rubella infection, medications , radiation exposure Family history: family members with CHD Present ill history: all possible cardiac symptoms failure to thrive, feeding difficulty, cyanosis, squatting, respiratory distress, sweating, pallor, syncope.
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30. General Examination Poor development Central cyanosis arterial deoxygenation (right - left shunt) Respiratory distress poor systemic output, increased pulmonary blood flow, heart failure Clubbing of fingers or toes prolonged hypoxia
31. Inspection Protrusion of the left precardium and sternum often indicates right ventricular enlargment. Position and range of the apex beat Cardiac Examination
37. Electrocardiography(ECG,EKG) The utility of the ECG in the diagnosis of congenital heart disease is largely for the diagnosis of ventricular and atrial hypertrophy.
38. Echocardiography (UCG) The best way to diagnose CHD Safe, noninvasive and accurate. Demonstrate the structure of the components of the heart and the blood flow in the heart.
39. Catheterization Need to diagnose has decreased dramatically An invasive, radioactive modality Obtaining pressure measurement and accurate shunt flows which is beyond the scope of Echocardiography.
42. (VSD) a hole in the septum between the right and left ventricles. The shunt occurs predominantly during ventricular systole. Blood passes from the left to right ventricle and is ejected directly into the pulmonary artery along with systemic venous blood.
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44. Eisenmenger's syndrome Refers to patients with reversed or bi-directional shunt and sustained cyanosis as a result of a pulmonary vascular obstructive disease (PVOD) and pulmonary hypertension resulting from Long-term presence of the large left to right blood shunt.
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46. Large defect (>1cm): Manifestations of congestive heart failure: irritability, increased respiratory effort, poor feeding; tachycardia, tachypnea, dyspnea, pallor, diaphoresis, failure to thrive Recurrent respiratory infections Growth retardation Hoarseness in the voice: the recurrent laryngeal nerve being pressed by dilated pulmonary artery Symptoms
47. Hyperactive precordial impulse , and a thrill is often palpable Accentuated P2 The murmur: loud, low-pitched, harsh, holosystolic, and loudest along the left sternal border, less well localized than a small VSD, radiate to the right of the sternum Older children with Eisenmenger's syndrome: resting cyanosis , nail-bed clubbing Signs
50. ECG The ECG suggests left ventricular hypertrophy (LVH), and can show RVH as the pulmonary resistance rises. V 1 V 1 Inverted T wave suggests no pulmonary hypertension Upright T wave indicates pulmonary hypertension
60. Clinical manifestations Small ASDs usually go undiagnosed for years because children are asymptomatic and physical signs are subtle. Symptoms of congestive heart failure are rare compared to VSDs. However, a few patients do present with a history of recurrent respiratory tract infections . Symptoms
61. Signs Protrusion of the precardium may be seen and the right ventricular tap (a systolic lift) is especially palpable from the left sternal border to the midclavicular line. Systolic murmur due to an increased right ventricular stroke volume and relative pulmonary stenosis is heard best in the second intercostal space just along the left sternal border and usually is grade 2 to 3.
62. Signs Accentuated second heart sound with fixed and wide splitting the increased right ventricular volume prolonging the right ventricular systole the increased time interval between the aortic and pulmonic component of the second heart sound A soft mid-diastolic murmur the increased tricuspid flow and relative stenosis of the tricuspid is best appreciated along the lower left sternal border
66. UCG Echocardiography can define the precise position of the atrial defect and demonstrate the volume-loaded right ventricle. And it allows definition of the entire cardiac structure and the exclusion of associated defects.
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68. Treatment Surgical correction is accomplished under direct vision through a right atriotomy while on cardiopulmonary bypass. Most defects are closed by direct suture and surgical mortality is less than 1%.
69. Patent ductus arteriosus(PDA) An abnormal persistence of a normal fetal pathway between the main pulmonary artery and the descending aorta .
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74. Clinical manifestations Symptoms Children with small shunts will be asymptomatic. In the presence of a large shunt, signs and symptoms of congestive heart failure, and recurrent respiratory infections will exist.
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78. ECG Left ventricular hypertrophy may be present. Some cases also have left atrial hypertrophy. In patients with pulmonary hypertension due to increased blood flow, there is usually biventricular hypertrophy.
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82. Treatment Surgical ligation through a left thoracotomy is performed safely and at low risk after a noninvasive evaluation.
83. Tetralogy of Fallot (TOF) 1. Pulmonary stenosis 2. Ventricular septal defect 3. Overriding aorta 4. Right ventricular hypertrophy
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85. Pathophysiology Decrease in systemic arterial oxygen saturation and cyanosis is the main pathologic result caused by PS, VSD and overriding aorta oxygen-poor blood returning to the RV is shunted across the VSD to the LV, and/or pumped directly into the overriding aorta in the presence of marked PS Right ventricular outflow tract obstruction results in compensatory right ventricular hypertrophy.
86. The hemodynamic consequences and severity of clinical manifestations depend on the degrees of PS: mild PS:Pulmonary outflow resistance<systemic left to right shunt acyanotic or pink TOF moderate-severe PS: right to left shunt decreased pulmonary blood flow causes cyanotic insufficient blood oxygenation TOF A systolic murmur caused by PS P 2 is either faint or absent because of low pulmonary pressure
91. Growth and development may be delayed in severe untreated tetralogy of Fallot. Cardiac signs: The left sternal bordor may bulge forward A cardiac lift (right ventricular impulse) is palpable A systolic thrill is palpable in 50% of cases Systolic murmur: is frequently loud and harsh, heard best from the second to fourth intercostal spaces along the left sternal border pulmonary stenosis The pulmoanry component of the second heart sound is either faint or absent.
92. Chest x-Ray Concave main pulmonary arterial segment and remarkably clear lung fields owing to the diminished pulmonary blood flow. Boot-shaped heart The hypertrophied right ventricle makes the cardiac apex upturned The aortic knob is prominent or shiffted to the right .
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97. Laboratory findings Polycythemia and high hematocrit and hemoglobin Complications Cerebral thrombosis Brain abscess Bacterial endocarditis
98. Treatment Palliative surgery to increase pulmonary blood flow: Infants with symptomatic TOF in the first few months of age Corrective surgery: at around 6 m Hypercyanotic spells: Knee-chest position Oxygen inhalation Sedation Correct metabolic acidosis Propranalol
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