Pulmonary atresia with intact ventricular septum

1. Pulmonary atresia with intact ventricular septum

2. Pulmonary atresia and intact ventricular septum was first described in 1784 by Hunter • Robert M. Freedom- described the diversity of this malformation and emphasized the complexity of this disorder

3. Epidemiology • New England Regional Infant Cardiac Program identified 75 patients with this disorder- 3.1% of all infants enrolled in the study • Baltimore-Washington Infant Study defined the prevalence for this disorder as 0.083 per 1,000 live births

4. Levocardia, normal atrial relations, concordant atrioventricular connections, and concordant ventriculoarterial connections • Right ventricular outflow tract is imperforate. • Either membranous or muscular atresia. • The ventricular septum is intact.

6. Pulmonary blood flow is usually mediated by a PDA • Multiple direct aortopulmonary collaterals originating from the descending thoracic aorta may be the sole sources of pulmonary arterial supply rarely. • Nonconfluent pulmonary arteries, each supplied by a patent arterial duct may also occur rarely.

7. Morphogenesis Kutsche and Van Mierop theory • Pulmonary atresia with ventricular septal defect occurs earlier in cardiac morphogenesis than pulmonary atresia and intact ventricular septum. • Pulmonary atresia and ventricular septal defect occur early in cardiac morphogenesis, after partitioning of the truncoconal part of the heart but before closure of the ventricular septum.

8. Pulmonary atresia and intact ventricular septum occur after cardiac septation. • Reflects a prenatal inflammatory disease rather than a true congenital malformation Kutsche LM, Van Mierop LH. Pulmonary atresia with and without ventricular septal defect: A different etiology and pathogenesis for the atresia in the 2 types? Am J Cardiol 1983;51:932â

9. Few data to support an inflammatory process • Histopathological studies provided no evidence of inflammation.

10. Obligatory right-to-left shunt at atrial level-either a patent foramen ovale or true secundumatrialseptal defect • If the interatrial septum is intact -alternative pathways for systemic venous return - coronary sinus to left atrial fenestration.

11. Tricuspid Valve • Ranges from extreme stenosis to severe regurgitation • Severely regurgitant valve -dilated annulus. • The valve may exhibit Ebstein anomaly. • Extremely dysplasia also seen.

12. Patients with the largest right ventricles usually have severe tricuspid regurgitation with valves exhibiting features of Ebstein's anomaly and dysplasia. • A major management challenge with a poor overall prognosis.

13. Right Ventricle • Congenital Heart Surgeons Study (CHSS)-the use of the tricuspid diameter Z value • It is the diameter of the tricuspid valve normalized to body surface area. • Data from the CHSS showed that the Z value of the tricuspid valve correlated with the size of the right ventricular cavity(p <0.0001)

14. Relief of outflow tract obstruction with associated pulmonary insufficiency may result in remodeling with regression of hypertrophy that can result in real or perceived growth of the right ventricle Daubeney PE, Delany DJ, Anderson RH, et al. Pulmonary atresia with intact ventricular septum: Range of morphology in a population-based study. J Am CollCardiol 2002;39:1670 Freedom RM. How can something so small cause so much grief? Some thoughts about the underdeveloped right ventricle in pulmonary atresia and intact ventricular septum. J Am CollCardiol 1992;19:1038

15. Well developed RV with hypertrophy-inlet,trabecular and outlet well developed -good prognosis. Small RV cavity (66%)-poorer surgical outcomes Markedly increased RV dimensions-severe TR(associated Ebsteinsanomaly- 10-15 %)

16. The aortic arch is left sided • Aortic valve stenosis has been described in patients with pulmonary atresia and intact ventricular septum

17. Myocardial Abnormalities • Ischemia, fibrosis, infarction, and myocardial rupture have been observed • Myocardial disarray and ventricular endocardialfibroelastosis also seen.

18. Ventricular to coronary artery communications PA IVS is associated with ventriculo arterial connections(by large sinusoids) Usually seen in association with hypoplastic RV Connections are seen to commonly RCA,LAD (to LCX is rare) Blood flow Systole-High pressure RV to sinusoids Diastole-coronary artery to RV- ‘coronary steal'

19. Development Coronary circulation develops as isolated plexus of vessels. Connections first develop to ventricular cavity and later coronary arteries develop and connect to aorta. Pulmonary atresia-high RV pressure maintains RV to sinusoids patency

20. Coronary artery anomalies 1) right ventricle -to-coronary artery fistulas 2) coronary artery stenoses 3) coronary occlusions

24. Natural History Equal prevalence in male and female 50% newborns die in first month of life Majority die in first 3 months Survival beyond first year is rare. Survival upto 21 years reported.

25. Physical Examination Newborns with pulmonary atresia and intact ventricular septum become cyanotic and hypoxemic –along with closure of the patent arterial duct Cyanosis usually is apparent within hours of birth and is progressive

26. The left ventricle may be enlarged, and at the apex, its impulse may be forceful. The second heart sounds is single.(A2) A pansystolic murmur may be audible at the left lower sternal border(of tricuspid regurgitation.) Arterial duct murmur may be heard in the second and third left intercostal space

27. Radiographic Features The chest radiograph may demonstrate a heart that is only mildly enlarged or one that fills the entire chest cavity

28. Electrocardiographic Features Frontal QRS axis of + 30 to + 90 paucity of right ventricular forces left ventricular dominance or left ventricular hypertrophy Right atrial enlargement

29. The Electrocardiogram in Tricuspid Atresia and Pulmonary Atresia with Intact Ventricular Septum Circulation.1966; 34: 24-37

30. Electrocardiograms were studied in 37 patients with tricuspid atresia and in 20 with pulmonary atresia and intact ventricular septum. The results were correlated with angiocardiographic findings and postmortem examinations

31. Biatrial hypertrophy was noted in 81% of the electrocardiograms in patients with tricuspid atresia, whereas this pattern was seen in only two infants with pulmonary atresia and intact ventricular septum

32. In tricuspid atresia, left axis deviation was more common.  Pulmonary atresia - no instances of left axis deviation in the frontal plane.

33. Echocardiographic Features Functional status of the interatrial septum - obligatory right-to-left shunting. The size and morphology of the tricuspid valve ,RV Patency of ductus Degree of TR Ebsteins anomaly

34. Functional pulmonary atresia Lack of forward flow is due to high pulmonary artery pressure with poor right ventricular function or very severe tricuspid insufficiency. Pulmonary valve is morphologically normal but functionally closed

35. Cardiac cathetrisation • Groin approach • Catheter passed through IVC to RA • Easily passes to LA(PFO) • RV entry difficult if severe TR/RV hypoplasia • Ductusvisualised by left ventricular angiogram • Visualisation of coronary arteries • RV angiogram- • ventricular coronary communications • confirm PA

37. Management • PGE1 infusion to maintain ductal patency • Electively intubated and controlled ventilation • Metabolic acidosis to be corrected and ionotropic support if perfusion is inadequate • Adequately stabilized before any initial procedure

38. Surgical management • Goal is to achieve a two ventricular circulation with the right ventricle providing all blood flow to the lungs at a low filling pressures without residual right to left shunt • Goal should be achieved with • low moratality • promoting the growth of RV • minimizing the need for subsequent surgical procedures

39. RV cavity size and coronary artery anatomy are crucial in selecting appropriate treatment strategy

40. The options available include the following. • Surgical opening of the pulmonary valve and the right ventricular outflow tract. • Systemic arterial to pulmonary arterial shunt • Transcatheter opening of the pulmonary valve. • Maintaining ductusarteriosus patency. • Systemic venous to pulmonary arterial shunt. • Closing the tricuspid valve.

41. Venous to pulmonary arterial shunts Glenn procedure: end-to-end anastomosis of the SVC to the left pulmonary artery. Cavopulmonaryanastomosis or bidirectional Glenn procedure: anastomosis of the SVC to the pulmonary artery so that both lungs can be perfused by SVC blood. Atriopulmonary connection or Fontan procedure: Anastomosisof the right atrial appendage to the pulmonary artery to divert all venous return into the pulmonary artery.

42. Severe pulmonary stenosis or pulmonaryatresia with well-developed right ventricleand mild or no tricuspid regurgitation Surgical pulmonary valvotomy with patch closure Balloon valvuloplasty

43. Pulmonary atresia with well-developedright ventricle and marked tricuspidregurgitation SVC to pulmonary artery communication (bidirectional Glenn procedure) can be performed in addition to valvotomy.

44. Pulmonary atresia with hypoplastic rightventricle and tricuspid valve Tricuspid valve diameter less than 8 mm in a newborn infant Tricuspid to mitral valve diameter ratio less than 0.7 Tricuspid valve diameter Z-scores of –3 or smaller

45. Management Bidirectional Glenn procedure

46. Pulmonary atresia with hypoplastic rightventricle and coronary sinusoids Attempts to open the RVoutflowtract are contraindicated. Systemic-to-pulmonary arterial shunt or prolonged PGE1 infusion is recommended. After the age of 3–4 months, cavopulmonaryanastomosis may be performed.

49. Risk factor for death after initial procedure • Low birth weight • Small tricuspid valve • RV dependent coronary circulation

50. Prognosis and long-term results afterprocedures Balloon valvuloplasty performed in the neonatal period may not be veryeffective in relieving stenosis. Cyanosis may persist and repeat valvuloplasty may be necessary within 6–9 months. Residual pulmonary valve insufficiency