Congenital Heart Disease

1. Congenital Heart Disease Jie Tian M.D. Children’s Hospital of CUMS

8. Epidemiology of CHD • Prevalence • CHD occurs in 0.5-0.8% of live births; • The incidence is higher among stillborns死产(3-4%), abortuses流产(10-25%), and premature infants (about 2% excluding PDA); • About 2-3 in 1,000 newborn infants will be symptomatic with heart disease in the first year of life.

9. Epidemiology of CHD • Prevalence • The diagnosis is established by 1 week of age in 40-50% of patients with CHD and by 1 month of age in 50-60% patients; • With the advances in both palliative姑息and corrective surgery of the last 20 years, the number of children with CHD surviving to adulthood has increased dramatically;

10. Epidemiology of CHD • Prevalence • Despite these advances, CHD remains the leading cause of death in children with congenital malformations; • Most congenital defects are well tolerated in the fetus because of the parallel nature of the fetal circulation.

11. Epidemiology of CHD • Etiology • The cause of most CHD is unknown. • Genetic factors play some role in CHD. • About eight percent of cases result mainly from genetic factors. The heart defect is usually part of a chromosomal disorder such as Down's syndrome. However, no specific gene locus for CHD has been identified.

12. Epidemiology of CHD • Etiology • A child born to a parent with CHD has a substantially大体上increased likelihood of having a similar congenital lesion. The risk may be as high as 15 percent. For certain lesions, there appears to be a greater risk of transmission from the mother than from the father.

13. Epidemiology of CHD • Etiology • About two percent of cases of CHD are primarily the result of environmental or external factors. Such factors include rubella风疹infection and ingestion of certain drugs, such as lithium锂. CHD is a prominent component of the fetal alcohol syndrome. • The etiologic role of other agents, such as anticonvulsant medications and exogenous外源female sex hormones, is uncertain.

14. Noninvasive Diagnostic Studies • Chest X ray • The location of the heart • The size of the heart • The relationship between heart and great vessel • The blood flow of the lung

16. Noninvasive Diagnostic Studies • Echocardiography • Echocardiography has great value in assessing congenital cardiac anomalies and should usually be the first advanced diagnostic study to be carried out if the history, the physical examination, the chest X ray, and the electrocardiogram suggest the presence of congenital heart disease.

17. Noninvasive Diagnostic Studies • Echocardiography • The standard M-mode display and the two-dimensional display provide such information about cardiac anatomy as • the size of the cardiac chambers, • the connections of the great vessels, • abnormalities of the valves, • and subvalvular obstructions.

18. Noninvasive Diagnostic Studies • Doppler ultrasonography • Doppler ultrasonography is useful in detecting septal defects and directly assessing the amount of blood that shunts through the defect. • The size of the shunt through a septal defect can also be estimated from Doppler ultrasound studies by comparing the velocity of the blood flow through the aorta with velocity through the pulmonary artery.

20. Noninvasive Diagnostic Studies • Transesophageal echocardiography • Transesophageal echocardiography isparticularly valuable for assessing atrial septal defects, but it also visualizes other lesions effectively. Doppler studies are useful in assessing valvular stenosis and regurgitation as well.

22. Noninvasive Diagnostic Studies • Computed tomography (CT) • CT provides a good display of the anatomic abnormalities associated with congenital heart disease and offers advantages over echocardiography in demonstrating anomalies involving the great vessels.

23. Computed tomography

24. Noninvasive Diagnostic Studies • Magnetic resonance imaging (MRI) • MRI provides information similar to that provided by CT. • MRI offers better resolution than CT without the disadvantages of the radiopaque不透射线的contrast medium used in that technique.

27. Noninvasive Diagnostic Studies • Cardiac catheterization and selective angiocardiography • are the most definitive diagnostic techniques currently available for use in congenital heart disease. • However, noninvasive studies often provide information that is equivalent to that obtained from cardiac catheterization and is sufficient for planning surgical treatment.

29. Congenital Cardiac Anomalies in Children • Ventricular Septal Defect (VSD) • VSD is the most common congenital cardiac anomaly in infants. It is rarely seen in adults because substantial VSD that are not corrected surgically are associated with a high mortality. In addition, the incidence of spontaneous closure of VSD is relatively high; closure occurs particularly often in infancy but also in later years.

31. Congenital Cardiac Anomalies in Children • Ventricular Septal Defect • The VSD that do appear in adults as isolated anomalies are usually less than 1 cm in diameter. Because the opening is quite small, normal systolic pressure can be maintained in the right ventricle and in the pulmonary artery.

32. Congenital Cardiac Anomalies in Children • Ventricular Septal Defect • In infants with a large VSD, medical management has two aims: to control heart failure and to prevent the development of pulmonary vascular disease. Therapeutic measures are aimed at the control of heart failure symptoms and the maintenance of normal growth.

33. Congenital Cardiac Anomalies in Children • Ventricular Septal Defect • Indications for surgical closure of VSD include patients at any age with large defects in whom clinical symptoms and failure to thrive cannot be controlled medically. • Infants between 6 and 12 mo of age with large defects associated with pulmonary hypertension, even if symptoms are controlled by medication.

34. Congenital Cardiac Anomalies in Children • Ventricular Septal Defect • Surgical closure is usually undertaken to prevent infective endocarditis . The incidence of this complication is not well established, but surgery appears to be highly effective as a prophylacticmeasure.

35. Congenital Cardiac Anomalies in Children • Atrial Septal Defect (ASD) • ASD is the most frequent congenital lesion of major importance in adults. It is often not diagnosed until adult life, even in the present era, because it rarely produces symptoms in childhood and the associated physical signs are easily confused with the cardiac findings in normal children.

36. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • Three types of atrial septal defect are classified on an anatomic basis: ostium secundum第二孔, sinus venosus, and ostium primum第一孔. All three types are associated with a left-to-right shunt at the atrial level and volume overwork of the right ventricle.

38. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • Blood is chronically overcirculated through the lungs at normal intracardiac pressure levels. Increased flow through the pulmonary valve produces a characteristic pulmonary systolic ejection murmur. The pulmonary valve closes late because of the reduced impedance阻抗in the pulmonary arterial system, causing a wide splitting of the second heart sound, the other classic finding in ASD.

39. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • The splitting remains relatively fixed in relation to respiration;the aortic and pulmonary components remain audibly split during expiration. A chest x-ray usually reveals enlargement of the heart and signs of pulmonary overcirculation, such as a large pulmonary trunk and increased pulmonary vascular markings. The relative severity of these conditions reflects the size of the left-to-right shunt.

40. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • Two major complications of ASD are pulmonary arterial hypertension and right ventricular failure. Pulmonary arterial hypertension is caused by elevated pulmonary vascular resistance; it develops after adolescence in about 15 percent of cases. In the most severe cases, an irreversible plexiform arteriopathy丛状的动脉病, similar to that seen in Eisenmenger syndrome or primary pulmonary hypertension, is present.

41. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • As a result of pulmonary hypertension, the left-to-right shunt first decreases, then becomes bidirectional, and finally reverses; a right ventricular pressure overload develops, pulmonary blood flow is reduced, and the patient becomes cyanotic.

42. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • Right ventricular failure develops as a result of long-standing volume overload; it usually affects patients older than 40 years. Right ventricular failure is usually associated with atrial flutter or fibrillation and is often linked to tricuspid regurgitation. Eventually, a syndrome of right- and left-sided congestive heart failure develops, and at this stage, it may be difficult to differentiate clinically between ASD and such conditions as cardiomyopathy and mitral valve disease.

43. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • Surgical closure of ASD is a very safe and highly effective procedure. Prophylactic surgery is therefore indicated in any patient in whom the ratio of pulmonary blood flow to systemic blood flow is 2:1 or greater. Nearly all patients in whom ASD can be clinically diagnosed exhibit at least this degree of left-to-right shunt.

44. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • Surgery is contraindicated 治疗或处置不当 when pulmonary hypertension approaches the pressure level of the systemic circulation because in such patients the operative mortality is high and the elevated pulmonary vascular resistance does not fall after surgery.

45. Congenital Cardiac Anomalies in Children • Atrial Septal Defect • Nonsurgical closure using cardiac catheterization with an umbrellalike device has been accomplished in patients with defects less than 2 cm in diameter, most of whom have been infants or small children.

46. Congenital Cardiac Anomalies in Children • Tetralogy of Fallot • The essential anatomic components of tetralogy of Fallot are ventricular septal defect and pulmonary stenosis. The degree of stenosis is usually severe enough to cause a predominantly right-to-left shunt, cyanosis, and diminished pulmonary blood flow. The pulmonary stenosis may be either valvular or infundibular; the infundibular form usually predominates in adults.

47. Congenital Cardiac Anomalies in Children • Tetralogy of Fallot • The other two anatomic features present in tetralogy of Fallot are an overriding aorta and right ventricular hypertrophy. Variations exist in the degree of dextroposition of the aorta, but this anatomic defect rarely has functional importance.

49. Congenital Cardiac Anomalies in Children • Tetralogy of Fallot • The technique of the totally corrective operation has been well established since the 1960s, and the defect is usually repaired in infancy or childhood. Patients who survive to adulthood without an operation or with only a palliative shunt operation, in which a systemic artery is anastomosed汇合to the pulmonary artery, may display fairly good effort tolerance, show little or no cyanosis, and have a seemingly good prognosis.

50. Congenital Cardiac Anomalies in Children • Tetralogy of Fallot • Such patients, however, may become increasingly disabled as a result of gradual shunt closure and the progression of infundibular pulmonary stenosis. Furthermore, such complications as infective endocarditis, cerebral thromboembolism, and brain abscess may arise if the anomaly is not repaired .