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Congenital_Heart_Disaese.pptx
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- 2. Congenital heart diseaseis a general term used to describe abnormalities of the heart or great vessels that are present from birth. Most such disorders arise from faulty embryogenesis, during gestational weeks 3-8, when major cardiovascular structures undergo development.
- 3. Clinical consequences: The variousstructural abnormalities in hearts with congenital defects fall primarily into two major categories: i) shunts or ii) obstructions. Shunt--A shunt is an abnormal communication between chambers or blood vessels (or both). Abnormal channels permit the flow of blood from left to right or the reverse, depending on pressure relationships.
- 4. When blood fromthe right side of the heart enters the left side (right-to-left shunt), a dusky blueness of the skin and mucus membranes (cyanosis) results because poorly oxygenated blood enters the systemic circulation. Congenital heart defects that produce right-to- left shunts from early infancy are known as cyanotic congenital heart disease. In contrast, left to right shunts are not initially associated with cyanosis. But these can result
- 5. in progressive pulmonaryhypertension and right ventricular overload with hypertrophy. The presence of a shunt may expose the pulmonary circulation to increased volume or pressure in congenital heart disease. Shunts associated with increased pulmonary blood flow include atrial septal defects(ASDs,) and shunts associated with both increased pulmonary blood flow and pressure include ventricular septal defects (VSDs) and patent ductus arteriosus(PDA).
- 6. The muscular pulmonaryarteries first respond to increased pressure by medial hypertrophy and vasoconstriction. This maintains relatively normal distal pulmonary capillary and venous pressures and prevents pulmonary edema. Prolonged pulmonary arterial vasoconstriction stimulates the development of irreversible obstructive intimal lesions. Consequently the pressure on the right side of the heart can rise to exceed that on the left.
- 7. This may reversethe shunt to right-to left which is called late cyanotic congenital heart disease. Once significant irreversible pulmonary hypertension develops, the structural defects of congenital heart disease are considered irreparable. The secondary pulmonary vascular changes eventually lead to the patient’s death.
- 8. Clinical finding frequentlyassociated with severe long standing cyanosis include clubbing of the tips of the fingers and toes and polycythemia. Cerebral thrombosis in very young children sometimes occurs in these settings. This is due to polycythemia and consequent increased blood viscosity and dehydration.
- 9. Obstructions---Some developmental anomalies ofthe heart produce obstructions to flow because of abnormal narrowing of chambers, valves or blood vessels. Prime examples are-- i) valvular stenoses (partial narrowing) or ii) artresias (complete obstruction) iii) coarctation of the aorta, iv) aortic valvular stenosis and v) pulmonary valvular stenosis These are called obstructive congenital heart disease.
- 10. In congenital heartdisease, altered hemodynamics usually cause cardiac dilatation or hypertrophy (both). A decrease in the volume and muscle mass of a cardiac chamber is called hypoplasia if it occurs before birth and atrophy if it develops after birth. Children with significant congenital cardiac defects may also fail to thrive, may suffer from retarded development, and are at greater risk of developing the usual disease of childhood.
- 11. Left-to-right shunts (Latecyanosis) 1. Atrial Septal Defect (ASD): An ASD represents an abnormal opening in the atrial septum that allows free communication of blood between the right and left atria. An ASD is the most common congenital cardiac anomaly that may first come to clinical attention in adults. ASDs result in a left to right shunt, because pulmonary vascular resistance is considerably less than systemic vascular resistance.
- 12. Besides, the compliance(distensibility) of the right ventricle is much greater than that of the left. Pulmonary blood flow may be 2-4 times normal. A murmur is often present which is due to excessive flow thought the pulmonary valve.
- 15. 2. Ventricular SeptalDefect (VSD): A VSD represent an abnormal opening in the ventricular septum that allows free communication between right and left ventricles. It is the most common congenital cardiac anomaly. Frequently VSD is associated with other structural defects, particularly tetralogy, transposition, PDA, ASD and aortic coarctation.
- 16. The functional significanceof a VSD depends on the size of the defect or the presence or absence of pulmonary stenosis. Small defects (<0.5 cm in diameter) close spontaneously (50%) and the remainder are generally well tolerated for years. They induce a loud murmur during systole. Large defects generally remain patent and permit a significant left-to-right flow. They also induce cardiac murmur at birth. Right ventricular hypertrophy and pulmonary hypertension are present from birth.
- 17. Overtime, irreversible pulmonaryvascular disease develops in all patients with large unoperated VSDs, leading to shunt reversal, cyanosis, clubbing and polycythemia. Surgical closure of incidental VSD is generally not done during infancy, in hope of spontaneous closure. But correction is indicated in older children with large defects, before obstructive pulmonary vascular disease develops and renders the lesion inoperable.
- 20. 3. Patent DuctusArterious (PDA): PDA results when the ductus arteriosus, a normal aortopulmonary vascular channel during intrauterine life remains open after birth. In a full term infant, the ductus usually closes functionally within the first day or two of life. In contrast, in premature infants with respiratory distress syndrome at birth, the ductus may remain patent. In full-term infants with PDA there may be a true structural defect in the wall.
- 21. A PDA shouldbe close as early in life as is feasible. Up to the recent past, operative closure was recommended. Currently indomethacin (suppress vesodilatory PGE synthesis) have proved promising. Ironically the ductus may be either life threatening or life saving.
- 24. 4. Atrio-Ventricular SeptalDefects (AVSD): AVSDs result from abnormal development of the embryologic AV canal, in which the superior and inferior endocardial cushions fail to fuse adequately resulting in incomplete closure of the AV septum. All four cardiac chambers freely communicate, inducing volume hypertrophy of each. More than one- third of all patients with the complete AV septal defect have Down syndrome. Surgical repair is possible.
- 25. Right-to-left shunts (Earlycyanosis) 1. Tetralogy of Fallot: The four features of Fallot tetralogy are-- i) VSD ii) obstruction to the right ventricular outflow tract (sub pulmonary stenosis) iii) an aorta that overrides the VSD iv) right ventricular hypertrophy. The clinical consequences of tetralogy of Fallot depend primarily on the severity of subpulmonary stenosis.
- 26. The severity ofobstruction to right ventricular outflow determines the direction of blood flow. If the sub pulmonary stenosis is mild, the shunt may be left-to-right without cyanosis. As the obstruction increase in severity, right-to-left shunting predominates along with cyanosis. As the child grows and the heart increases in size, the pulmonic orifice does not expand proportionally, making the obstruction ever worse. Thus most infants with tetralogy are cyanotic from birth or soon thereafter.
- 29. 2. Transposition ofgreat arteries: Transposition represents ventriculo-arterial discordance, such that the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle. This is an embryologic defect and occurs due to the abnormal formation of the truncal and aortopulmonary septa. Thus the aorta arises from the right ventricle and lies anterior to the right of the pulmonary artery (in the normal heart the aorta is posterior and to the right).
- 30. The result isseparation of the systemic and pulmonary circulation. This condition is incompatible with post natal life, unless a shunt exists for adequate mixing of blood. This malformation is particularly common in offspring of diabetic mother, causes cyanosis from birth. Patients with transposition and VSD have a stable shunt. Patients with only PDA have unstable shunts that tend to close.
- 31. This patient thereforerequire immediate intervention to open an right to left communication within the first few days of life. Risk factors: Expecting mother i) having diabetes ii) having rubella iii) having poor nutrition iv) consuming alchol v) being >40 years old
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