Congenital Heart Disease

1. Congenital Heart Disease Tammy L. Schena, RN, MSN, CCRN

2. Fetal Heart Development • Formation begins during 2nd week embryonic life • Contractions by 8th week • Sinus rhythm by 16th week

3. Epidemiology • 0.8% of all live births • Correlating factors: • chromosomal abnormalities (5-8%) • teratogenic factors (1%) • family history: • one parent with CHD = 2-4%  risk • mother with CHD may increase risk by 25%

4. Fetal Circulation • Oxygenation occurs in placenta • Fetal lungs bypassed • Fetal hypoxemia without tissue hypoxia • Very low SVR, very high PVR • fluid-filled alveoli

6. Circulatory Changes at Birth • Closure of foramen ovale • LA Pressure > RA Pressure • Closure of ductus arteriosus • rise in paO2 • decrease in endogenous prostaglandins

7. Circulatory Changes • Pulmonary vascular resistance: • breathing causes expansion of alveoli • alveolar hypoxia eliminated, rapid fall in PVR • pulmonary blood flow increases by 450% with onset of breathing

8. Factors contributing to vasoconstriction: hypoxia acidosis hypothermia Factors contributing to vasodilation: alveolar oxygenation alkalosis analgesia Pulmonary Circulation

9. Normal Heart Physiology • Saturations: • SVC, IVC, Coronary, Right atrium • Right heart filling pressures (CVP) • Left heart filling pressures • Coronary arteries

10. Cardiac Output • Cardiac Output = stroke volume x heart rate • stroke volume  contractility • infants are heart rate dependent • Oxygen delivery = cardiac output x O2 content • O2 content  Hgb, saturation

11. Cardiac Output (cont.) • Preload • amount of myocardial fiber stretch just before contraction • Starling’s Law • Afterload • pressure against which the ventricle must pump • A change in pressure or volume on one side of the heart has an effect on the other side

12. Preload: Fluid (CVP) Diuretics Increased airway pressure Pericardial tamponade SVT Afterload: Hypoxia Acidosis Vasoactive infusions Increased SVR Increased PVR Coarctation Contributing Factors

13. Congenital Heart Defect • A cardiac or extra-cardiac anatomic abnormality creating a disruption in the normal adaptation process • Heart or great vessels • Certain defects provide “transitional circulation”

14. CHD Classification • Lesions producing obstruction • atrial • ventricular • Lesions producing shunts: • cyanotic • acyanotic

15. Hemodynamics • What type of defect is present? • obstructive • cyanotic • acyanotic • How is cardiac output affected? • too high • too low

16. Patent Ductus Arteriosus (PDA) • Fetal vessel connecting PA to aorta • Usually closes by 5 - 7 days of age • PDA: blood flows from aorta to pulmonary artery

17. PDA Management • Indomethacin (Indocin) • Transcatheter closure (coil) • Surgical ligation • PDA may be life saving in some infants (“transitional circulation”)

18. Atrial Septal Defect (ASD) • Improper development of atrial septum • Communication between right & left atria • LA to RA shunt produces RV volume overload and increased pulmonary blood flow

19. ASD Management • Closure recommended • Open heart surgery by 4 - 6 years of age • sutured or patched • Transcatheter closure • “clamshell”

20. Ventricular Septal Defect (VSD) • Abnormal opening between ventricles • LV to RV shunt: increased blood flow to RV, PA, lungs • Prolonged increased pulmonary blood flow: irreversible pulmonary vascular disease

21. VSD Variations • Small: • pulmonary to systemic blood flow: 1.5 : 1 • Moderate: • pulmonary to systemic blood flow: 1.5 - 2 : 1 • Large: • pulmonary to systemic blood flow: > 2 : 1

22. Why are large VSDs bad? • Pulmonary blood flow under high pressure • RVP = LVP: biventricular hypertrophy • Congestive heart failure • Eisenmenger’s Syndrome

23. VSD Management • Pulmonary artery banding • reduce pulmonary blood flow • prevent pulmonary hypertension • Open heart surgery with Dacron patch • Via RA through tricuspid valve • Right ventriculotomy • Rarely left ventriculotomy

24. Atrioventricular Canal Defect • Malformation of endocardial cushion: atrial septum, ventricular septum and AV valves • Usually acyanotic: • produces increased pulmonary blood flow

25. AV Canal management • Medical management of CHF • Digoxin • Lasix • Surgical correction • Dacron patches • valvuloplasties

26. Tetralogy of Fallot • 4 defects: • VSD, PS, RVH, overriding aorta • Cyanosis proportional to degree of PS • Minimal cyanosis until PDA closes

27. Tet Management • Infancy • Blalock-Taussig (BT) shunt • Modified B-T shunt • CHF management (digoxin and diuretics) • Surgical correction at 8 mos to 3 years • VSD closure • RVOT reconstruction (patch)

28. Blalock-Taussig Shunt

29. Modified B-T Shunt

30. Transposition of Great Arteries (TGA) • Aorta arises from RV • Pulmonary artery arises from LV • Must have septal defect or PDA for shunting • Extreme cyanosis

31. TGA Management • IV Prostaglandin for patency of PDA • Balloon atrial septostomy (Rashkind) if no ASD present • Arterial Switch procedure • proximal aorta and PA transected & reattached • coronary arteries transposed to new ascending aorta position

32. Arterial Switch

33. Truncus Arteriosus • Entire pulmonary, systemic & coronary circulations supplied from one common trunk • Large VSD • RV & LV function as single ventricle

34. Truncus Management • Management of CHF with digoxin & diuretics • Surgical correction • right ventriculostomy for VSD closure • common trunk becomes aorta • conduit with valve from RV to PA (Rastelli procedure)

35. Tricuspid Atresia • Complete obstruction of blood flow from RA to RV • Blood flow: • RA to LA via PFO • Systemic & pulmonary blood mix in LA • Through VSD to PA

36. Tricuspid Atresia Management • Must be immediately palliated • Surgeries done in multiple stages with final procedure Fontan (right atrial to pulmonary artery conduit)

37. Tricuspid Atresia (cont.) • 1. Glenn Anastomosis • initial step in preparation for Fontan • goal is to separate systemic from pulmonary blood flow • SVC detached from RA and sutured to right PA (~40% of venous blood delivered to PA) • advantages:  cyanosis,  LV blood • disadvantage: SVC syndrome

38. Glenn Shunt

39. Tricuspid Atresia (cont.) • 2. Fontan • final operative procedure • IVC removed from RA, oversewn, joined to PA via homograft • complete extra-cardiac conduit • systemic venous return directly to lungs • passive flow of blood through PA

40. Fontan

41. Fontan (cont.) • Used for any “single ventricle” physiology • tricuspid atresia • hypoplastic left heart syndrome • severe pulmonary atresia • Modified Fontan: • conduit joining RA to RV to PA • Avoid variables that cause increases in PVR

42. Total Anomalous Pulmonary Venous Return (TAPVR) • Failure of pulmonary veins to empty into LA • Oxygenated blood returns to the right heart • ASD present • paO2 will be the same on either side of the heart

43. TAPVR Management • Control of CHF: prevention of pulmonary vascular disease • Surgical correction: • dissect and reattach pulmonary veins to left atrium • potential for attachment site obstruction

44. Coarctation of the Aorta • Narrowing of aorta ranging from mild to severe • Bicuspid aortic valve • Extreme version: interrupted arch • Preductal or postductal

45. Coarctation of the Aorta

46. Coarctation Management • IV Prostaglandin E1 • Preductal coarctation: descending aorta flow dependent on PDA • Surgical resection, any age, depends on severity • subclavian artery flap, Dacron patch • end-to-end anastomosis • post-operative complications increase with increased age

47. Hypoplastic Left Heart Syndrome • Severe hypoplasia of left ventricle • Usually includes mitral or aortic stenosis/atresia, coarctation • ASD present

48. HLHS Management • IV Prostaglandin E1 • PDA for blood flow to aorta and coronaries • Three options • comfort measures only • cardiac transplantation • surgical palliation: Norwood

49. HLHS (cont.) • Norwood: • PA transected from RV • Aorta created with homograft and sewn to RV, essentially creating a “truncus” • B-T shunt created for pulmonary blood flow • ASD/PFO maintained for unrestricted LA to RA blood flow

50. Pearls • Goal of treatment is adequate CO and vital organ oxygenation • A change in pressure or volume on one side of the heart will have an effect on the other • The magnitude of a shunt is dependent on pressure gradient which determines flow