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Congenital heart diseases 1

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Congenital heart diseases 1

  1. 1. Congenital Heart DiseasesByDr.jawharLecture 1
  2. 2. Congenital Heart DiseasesIncidence: Most common type heart disease among children. Incidence is 1% of live births. The incidence is higher in premature infants andin stillborns.Etiology and Pathogenesis: Chromosomal abnormalities ( trisomies 13, 15, 18,and 21, and Turner syndrome). Trisomy 21 ( Down syndrome) is most commongenetic cause of CHD.
  3. 3.  Environmental factors: congenital rubella orteratogens. Multifactorial : genetic, environmental, andmaternal factors account for remaining of cases.Clinical Features:CHD fall into three major categories: Malformations causing left-to-right shunt. Malformations causing right-to-left shunt . Malformations causing obstruction.
  4. 4. LEFT-TO-RIGHT SHUNTS: Cause cyanosis several months or yearsafter birth. Include:o Atrial Septal Defects( ASD)o Ventricular Septal Defects( VSD )o Patent (or persistent) Ductus Arteriosus( PDA)o AV Septal Defects (AVSD ).Atrial Septal Defect ( ASD ): Abnormal opening in atrial septum. Usually asymptomatic until adulthood.
  5. 5.  Usually isolated ( not associated with otheranomalies). Irreversible pulmonary hypertension developsin fewer than 10% of cases. Mortality is low, and postoperative survival iscomparable to that of normal population.
  6. 6. Morphology: Three major types classified according to theirlocation in septum : secundum, primum, andsinus venosus.o Secundum ASD ( 90% of ASDs ) located at andresulting from a deficient oval fossa.o Primum ASD (5% of ASDs) occur adjacent to AVvalves .o Sinus venosus defects (5%) located near entranceof superior vena cava.
  7. 7. Ventricular Septal Defect (VSD ): Incomplete closure of ventricular septum. Associated with other defects, such as tetralogyof Fallot ( 70% ). 30% occur as isolated anomalies.Morphology: 90% involve region of membranous septum(membranous VSD). The remainder ( 10% ) lie below pulmonary valve(infundibular VSD) , or within muscular septum. 50% of small muscular VSDs close spontaneously.
  8. 8.  Large defects:o Membranous or infundibular.o Remain patent and permit significantleft-to-right flow.o Right ventricular hypertrophy and pulmonaryhypertension are present from birth.o Over time, irreversible pulmonary vascular diseasedevelops leading to shunt reversal ( right to left ),cyanosis, and death.o Correction is indicated at age 1 year beforebecomes irreversible.
  9. 9. Patent Ductus Arteriosus ( PDA ): Ductus arteriosus remains open after birth. 90% occur as an isolated anomaly. The remainder ( 10% ) are associated with VSD,coarctation of aorta, or pulmonary or aortic stenosis. Continuous harsh murmur "machinery-like" The shunt first is left-to-right, so no cyanosis. Obstructive pulmonary vascular diseaseeventually ensues.
  10. 10.  Conversely, preservation of ductal patency(by administering prostaglandin E) assumes greatimportance in survival of infants with various CHDsuch as aortic valve atresia. Therefore PDA may be either life-threatening, orlife-saving.
  11. 11. Atrioventricular Septal Defect (AVSD): Abnormal development of AV canal. Superior and inferior endocardial cushions failto fuse adequately. Resulting in incomplete closure of AV septum andinadequate formation of tricuspid and mitral valves .
  12. 12. RIGHT-TO-LEFT SHUNTS:Cause cyanosis early in postnatal life:Tetralogy of Fallot: Four features of tetralogy of Fallot are:(1) VSD.(2) obstruction to right ventricular outflow( subpulmonary stenosis).(3) aorta that overrides VSD.(4) right ventricular hypertrophy.
  13. 13.  The clinical consequences depend on severityof subpulmonary stenosis:o If mild, the abnormality resembles an isolated VSDand the shunt may be left-to-right without cyanosis(pink tetralogy).o If sever, there is greater resistance to rightventricular outflow , right-to-left shunting withcyanosis (classic tetralogy of Fallot).
  14. 14. Morphology: The heart is often enlarged and may be"boot-shaped“ owing to marked right ventricularhypertrophy, particularly of apical region. The VSD is usually large.
  15. 15. Transposition of Great Arteries (TGA): Aorta arises from right ventricle andpulmonary artery emanates from left ventricle. The AV connections are normal ( with right atriumjoining right ventricle and left atrium emptyinginto left ventricle). The result is separation of systemic and pulmonarycirculations, a condition incompatible with postnatallife unless a shunt exists for adequate mixing ofblood.
  16. 16.  Patients with TGA and VSD ( 35%) have a stableshunt. Those with only patent foramen ovale or PDA ( 65%)have unstable shunts that tend to close , thereforerequire immediate intervention to create a shunt(such as balloon atrial septostomy) within first fewdays of life.
  17. 17. Truncus Arteriosus : Developmental failure of separation of embryologictruncus arteriosus into aorta and pulmonary artery. This results in a single great artery that receivesblood from both ventricles. Because blood from right and left ventricles mixes,there is early systemic cyanosis.
  18. 18. Tricuspid Atresia : Complete occlusion of tricuspid valve orifice . Associated with underdevelopment (hypoplasia)of right ventricle. The circulation is maintained by a right-to-left shuntthrough inter-atrial communication (ASD or patentforamen ovale). Cyanosis is present from birth, and there is highmortality in first weeks or months of life.
  19. 19. OBSTRUCTIVE CONGENITAL ANOMALIES:Coarctation of Aorta: Two classic forms :(A) Infantile form : proximal to PDA.(B) Adult form : just opposite the closed ductusarteriosus (ligamentum arteriosum).
  20. 20. (A) Infantile form: leads to manifestations early in life. do not survive without surgical intervention. Unoxygenated blood through PDA produces cyanosisin lower half of body.
  21. 21. (B) Adult form: most of children are asymptomatic. may go unrecognized until adult life. hypertension in upper extremities, but weak pulsesand lower blood pressure in lower extremities. manifestations of arterial insufficiency(claudication and coldness).
  22. 22. Pulmonary Stenosis and Atresia: Obstruction at pulmonary valve, may bemild to severe. May occur as an isolated defect, or as part oftetralogy of Fallot . Right ventricular hypertrophy often develops. Mild stenosis may be asymptomatic and compatiblewith long life. Sever stenosis is associated with cyanosis andearlier appearance.
  23. 23. Aortic Stenosis and Atresia: Three major types : valvular, subvalvular, andsupravalvular. Prominent systolic murmur and sometimes a thrill. Hypertrophy of left ventricle. Well tolerated unless very severe. Mild stenoses can be managed conservatively withantibiotic prophylaxis and avoidance of strenuousactivity. Sudden death with exertion always expected.

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