Pulmonary atresia with ventricular septal defect

Describes pulmonary atresia with ventricular septal defect

1. Pulmonary Atresia with VSD Dr.Anish P G

2. Pulmonary atresia with VSD defect is considered as the most severe form of tetralogy of Fallot (TOF) Unlike TOF RVOT ends blindly All of the RV stroke volume is directed to the aorta via the VSD The PA architecture is much more complex S evere abnormalities in the size and distribution of the PA branches and well-developed systemic collateral vessels that supply all or portions of the lung parenchyma . In extreme cases, the pulmonary vascular tree can even be composed of discontinuous segments, each with an independent source of flow.

3. Accounts for about 2 % of congenital heart disease ( CHD) It is one of the common causes of cyanosis and hypoxemia in the neonate. More prevalent in male infants. Baltimore-Washington Infant Study (BWIS ) Prevalence of 0.07 per 1 ,000 live births was observed for PA-VSD and PA-VSD accounted for 20.3 % of all forms of TOF

4. Environmental factors and genetics Increased risk of conotruncal defects Maternal diabetes Maternal phenylketonuria (PKU) Maternal exposure to Retinoic acids Trimethadione BWIS Infants of diabetic women had nearly a 10-fold increased risk of devel­oping PA-VSD

5. The extent of pulmonary artery atresia Variable I nvolves the central pulmonary arteries either proximally and/or distally The atretic arterial segment S olid elastic cord in about 75 % of the cases but is unidentifiable in the other cases. Most commonly T he pulmonary valve and the proximal portion of the pulmonary trunk (PT) are involved Rarely Only the pulmonary valve i s imperforate.

6. The central, RPA and LPA and/or the segmental pulmonary arteries can be confluent or nonconfluent .

7. Blood supply to the lungs E ntirely from the systemic arterial circulation. Ductus arteriosus Systemic-to-pulmonary collateral arteries Occasionally a coronary artery Plexuses of bron­chial or pleural arteries Unifocal blood supply A single systemic arterial source to a lung Multifocal blood supply Multiple sources

8. Ductal and collateral sources may coexist in the same patient but only rarely coexist in the same lung.

9. The caliber of the central pulmonary arteries varies considerably D irectly related to the amount of blood flow . Mildly hypoplastic or normal in size When the ductus or collateral arteries connect proximally to the central pulmonary arteries or their lobar branches Severely hypoplastic W hen multiple collateral arteries are anastomosed more distally at segmental or subsegmental levels S tenosis of the systemic arterial channels , either congenital or acquired, can be associated with hypoplasia of the central pulmonary arteries

10. Patterns of intrapulmonary arterial distribution Determined by the types of systemic arterial blood supply When a ductus supplies confluent central pulmonary arteries T he intrapul­monary arteries of both lungs are normal When nonconflu­ent central pulmonary arteries are present L ung supplied by a ductus U nifocal blood supply Normal arterial distribution C ontralateral lung Multifocal blood supply Fragmented pulmonary arterial distribution (so-called arborization abnormality) When both lungs are supplied b y multiple collateral channels I ntrapulmonary arborization abnormalities D uctus is absent .

11. Ductus arteriosus Usually is a unilateral structure A/w conflent pulmonary arteries in >80% of cases B ilateral A/w nonconflent pulmonary arteries Rare Ductus Vs Collaterals The ductus does not branch before joining the central pulmonary arteries L ess tortuous than collaterals

12. P ul­monary arteries may be of normal size at birth N or­mal postnatal ductal narrowing P roduces distal stenosis in 35 % to 50% of cases B lood flow to the lungs is diminished R elative hypoplasia of the pulmonary arteries becomes more severe as the child grows

13. Collateral arteries A rise from Descending thoracic aorta Subclavian arteries Abdominal aorta or its branches Coronary arteries 1 to 6 in number D iameter ranges from 1 to 20 mm Stenoses in nearly 60% tend to occur near the aortic or intrapulmonary anastomoses . discrete or segmental, con­genital or acquired

14. Anastomoses between the central PA s (or their branches) and the collateral arter­ies 40% - At the hilum or within the lung 60% - Enter the pulmonary hilum, travel with the bronchi as PAs, and supply bronchopulmonary segments Although the central PAs are confluent in 2/3of the cases, they usually supply only a portion of each lung owing to the coexistence of multiple collateral arteries and arborization abnormalities

15. Stenosis of collaterals may develop progressively , and they may become inadequate as the patient grows Hyperperfusion of some bron­chopulmonary segments and hypoperfusion of others in the same patient leads to hypertensive pulmonary vascular disease as well as stasis thrombosis

16. VSD may be membranous or infundibular . tends to be larger than isolated membranous or infundibular defects. obstructed partially by accessory tri­cuspid valvular tissue rarely A orta Arises predominantly from the RV The ascending aorta characteristically is dilated the degree of dextroposition usually is less than with TOF Aortic valve insuffiiency may result from annular dilation or infective endocarditis. A right aortic arch is present in 26% to 50%

17. RA - dilated and hypertrophied LA - nusually is normal. OS ASD or PFO - present in about 50% TV orifice - normal size & minor leaflet abnormalities occur commonly Mitral valve orifice - normal or mildly hypoplastic RV hypertrophy - moderate to severe. The infundibulum ends blindly and may range in length from normal to very short. infundibular septum may be fused to the right ventricular wall . LVwall thickness - normal, chamber size tends to be normal or somewhat small in older patients LV may be hypertrophied and dilated.

18. Coronary arteries- usually normal. C onus artery tends to be prominent Coronary anomalies H igh origin of the coronary ostia C oronary-to PA fistulas O rigin of RCA from the left anterior aortic sinus , coursing across the right ventricular infundibulum

19. Sinus node - normal. AV node - normal position within the triangle of Koch. His bundle Proximal portion lies along LV aspect of the posteroinferior rim of the VSD . related closely to the rim of membranous VSD, but is relatively remote from the border of infundibular defects. left bundle branch – normal right bundle branch - bifid or form several aberrant branches

20. O ther anomalies a/w PA/VSD P ersistent left SVC to the coronary sinus A nomalies of the coronary sinus PAPVC/TAPVC TS or atresia C omplete AVSD D- or L-TGA D extrocardia H eterotaxia syndromes

21. Clinical Features **Often presents as a cyanotic newborn Increasingly hypoxic when PDA constricts Use of prostaglandin E1 is critical in the early neonatal period to maintain ductal patency and stabilize the patient prior to surgery . **Neonates with sufficient collaterals-not severely hypoxemic over time, hypoxemia and cyanosis increase as the patient outgrows the relatively fixed sources of pulmonary blood flow

22. **Rarely presents with heart failure and signs of increased pulmonary blood flow. M.C. at 4 to 6 weeks of age after the PVR has decreased. L arge PDA or large systemic- PA collateral vessels. S urgical intervention may be necessary . L arge PDA T he pulmonary arteries usually are well developed, and early complete repair may be feasible L arge collateral vessels T he true PAs frequently are hypoplastic with arborization abnormalities D efinitive correction more diffiult

23. Patients with microdeletion of 22q1 1 .2 tend to have more complex collateral and pulmonary arterial anatomy

24. PA-VSD who have had palliative surgical procedures In the absence of significant valve regurgitation, heart failure is uncommon. Worsening cyanosis P atients outgrow shunts per­formed early in life C omplications of shunts D istortion and stenosis of pulmonary arteries P ulmonary vascular obstructive dis­ease

25. M odifid BTS is the preferred palliative shunt. Alternatively Establishing a direct connection between the AA and the remnant of MPA Creating a nonvalved connection between the RV and hypoplastic confluent PA leaving the VSD open . P roduce more rapid enlargement of the central pulmonary arteries than systemic-to-peripheral pulmonary artery shunts Produce less distortion of the peripheral pulmonary arterial architecture.

26. Physical Examination Cyanosis may be mild immediately after birth, but it increases in severity during the first several days of life as the PDA closes If growth is delayed suspect the presence of a 22q1 1 .2 microdeletion . Heart failure caused by excessive pulmonary blood flw is uncommon in these patients ; therefore, growth failure on this basis is infrequent.

27. In neonatal period The peripheral pulses and blood pressure usually are normal in the neonatal period, even with a PDA in patients > 4 to 6 weeks of age pulmonary blood flow through a PDA, collaterals,or surgically created shunt is substantial, the pulses can be bounding , and only minimal cyanosis may be present. The cardiac impulse usually is most prominent at the lower LSB The heart size is normal for patients with normal or decreased pulmonary blood flw .

28. S1-normal Single & loud S2 systolic murmur may be audible along LSB but usually < grade 3/6 Because the RVOT is atretic , there is no separate loud ESM at the upper LSB(diff. with TOF) If a PDA is present, a continuous murmur usually is heard in > 4 to 6 weeks of life. If systemic­ to-pulmonary collateral vessels are present, continuous murmurs can be heard. be multiple and often are most prominent over the back (vessels usually originate from the descending aorta )

29. Electrocardiographic Features RVH & RAD BVH & LAE I n patients with increased pulmonary blood flow Electrocardiography helps in Differentiation of PA/VSD from PA/ IVS RV hypoplasia is present – in PA/IVS Diminutive anterior QRS forces with LV preponderance occur – in PA/IVS

30. X RAY coeur en sabot appearance Levorotation of the heart P rominent , upturned car­diac apex, secondary to RVH. C oncavity in the region of the MPA produced by underdevelopment of the subpulmonary infun­dibulum. Right-sided aortic arch 26 % to 50 % than in TOF (20% to 25 % ) The pulmonary vascular markings heterogeneous reticular appearance- collaterals In patients with a large PDA and normally developed central pulmonary arteries­ enlarged central pulmonary arteries with increased peripheral vascularity

31. Echocardiographic Features C annot completely delineate the distal PA tree or the sources of pulmonary arterial supply. C ardiac catheterization is necessary prior to definitive repair . ECHO Determine the presence (and size) of a central pulmonary arterial confluence D etect large collateral vessels D efine many associated cardiovascular malformations.

32. Parasternal long-axis view Similarity with TOF A large aortic valve that overrides a malaligned VSD The infundibular portion of the VS i s anteriorly malpositioned Difference with TOF I nfundibular septum has fused with the RV free wall in patients with PA-VSD N o separate outflow from the RV TOF patent , although hypoplastic , RVOT anterior to the malaligned infundibular septum. Outflow tract is in continuity with the MPA PA-VSD Vs truncus arteriosus PAs arise directly from the posterolateral aspect of the truncal root prior to the arch.

33. Suprasternal and high parasternal windows S ize and status of the proximal PAs . When the PAs are confluent and clearly identified by echo, newborns with ductal-dependent PBF can undergo a palliative systemic-to-PA shunt procedure without cardiac catheterization C olor flow imaging pulmonary arteries are nonconfluent pulmonary arteries are extremely hypoplastic , multiple collateral arteries are present in the area of the confluence .

34. Cardiac Catheterization and Angiocardiography

35. Before a defiitive operation, cardiac cath­eterization is mandatory to delineate T he size and distributionof the true pulmonary arteries To ascertain the extent of collateral blood supply to the lungs RA pressures are normal unless TR is present N o increase of oxygenation at the atrial level unless an associated ASD is present . RV pressure is equal to the LV pressure because of the large VSD . Since the RVOT is atretic , the catheter cannot be advanced into the pulmonary arteries from the RV , but can be manipulated easily from the RV through the VSD into the aorta. Aortic pressure is normal if PBF is normal or decreased. Widened pulse pressure may be present if there is a large runoff into the lungs through a PDA or a previously constructed shunt. Systemic arterial blood oxygen desaturation is present, and the degree depends on the volume of PBF.

36. The true PAP and resistance are nor­mal in most instances. increased PAP large PDA large communication between a systemic collateral vessel and the true PA a large fistula connecting the coronary artery to PA a large shunt anastomosis (Waterston and Potts shunts ) risk for developing pulmonary vascular obstructive disease. true PAs entered through the large communication, measure the pressure, and pulmonary flow ( Fick principle ) & PVR estimated

37. Angiocardiography useful during the preoperative evalu­ation Documenting the existence of multiple VSDs and anatomy of the coronary arteries Ventricular and aortic root angiography Ventriculography performed with an injection into the LV cavity 70-degree left anterior oblique view with 20 degrees of cranial angulation . displays the middle portion and most of the upper IVS tangentially. Aortic root angiocardiogram 70-degree left anterior oblique view (with or without20 degrees of cranial angulation) . For coronary artery anatomy LAD from RCA in 5 % of pts ** Sx importance previous surgical procedures result in pericardia ! adhesions that obscure the coronary anatomy.

38. I nitial aortogram to demonstrate the number and location of the systemic­ to-pulmonary collateral arteries Both the central and the peripheral pulmonary arteries must be demonstrated. detection of discrete stenoses or tubular hypoplasia involving the pulmonary arteries degree to which the central and peripheral pulmonary arteries communicate

39. Angiographic delineation o f the anatomy o f pulmonary blood supply retrograde arterial approach is used most often allows easier access to surgically created shunts or systemic collateral vessels . Determining the presence or absence of a central PA confluence is of paramount importance . detailed analysis of the systemic arterial collateral blood supply to the pulmonary artery tree needed Non selective aortography Selective injections to collateral arteries selective balloon occlusion techniques to delineate the extent of the pulmonary arterial tree supplied by each col­lateral vessel and to determine which type of PA connection is present

40. central and the peripheral PAs must be demonstrated. detection of discrete stenoses or tubular hypoplasia involving the pulmonary arteries degree of communication central and peripheral PA evanescent negative washout pat­tern - due to a stream of unopacified blood from a connecting PA flowing into an area of opacified PA tree retrograde pulmonary vein wedge injec­tion - to identify hypoplastic central PA

41. total dose of contrast not to exceed 5 to 6 mL of contrast material per kg body wt during any single procedure Adequate hydration before, during, and after the study is mandatory to prevent thromboembolic complication or a potential com­plication secondary to hyperosmolality caused by the contrast material.

42. DIFFER ENTIAL DIAGNOSIS cyanotic infant TOF, TGA, TA DORV with severe PS or PA , single ventricle with severe PS orPA TAPVC with pulmonary venous obstruction PA-VSD in whom the pulmonary blood supply is normal or increased lesions in which cyanosis is minimal and evidence of heart failure may be present VSD , large PDA, AVseptal defect DORV or single ventricle without signifiant PS persistent truncus arteriosus TAPVC without pulmonary venous obstruction.

43. TREATM ENT Medical Heart failure- in pts with excessive pulmonary blood flow Phlebotomy – polycythemia Surgical pulmonary artery architecture sources of pulmonary blood supply t he degree of communication between the central PA & (MAPCAs) must be determined preoperatively.

44. Surgical Palliative those patients whose PA anatomy precludes complete repair augment pulmonary arterial blood flw (systemic-pulmonary artery shunts, uni­focalization ) reduce pulmonary blood flow (interruption of unnecessary MAPCAs, unifocalization ) Complete repair RVOT reconstruction for inducement of central PA growth . RV to the central pulmonary artery conduit . promote growth of the hypoplastic central PA so that they are adequate for complete repair Unifocalization procedures disconnecting MAPCAs from their aortic origins, so that they can be positioned in the vicinity of the heart (or the central conflence ) for final connection to the RV Connections between non­ communicating segments are created, and a single source of flw is provided to the unifocalized lung. incorporate the maximum number of PA segments into the RVOT reconstruction .

45. complete repair defined as closure of all septal defects interruption of all extracardiac sources of pulmonary arterial blood flow incorporation of at least 14 pulmonary arterial segments in a connection to the RV Central PA size should be at least 50% of normal . At the end of operation, the RV pressure should be <60 % that measured in the LV , If higher, the VSD is fenestrated.

46. staged reconstructive surgical approach in patients who did not meet the criteria for complete repair at presentation lateral thoracotomies for " unifocalization " procedures to deal with signifiant arborization abnormalities of the PA to create a single, central arterial source for each lung. If operations were successful, the two reconstructed central pulmonary arteries were connected & Complete repair was performed at a later date.

47. Alternative single-stage unifocalization /complete repair approach previously unoperated pts with PA-VSD. McElhinney e t al. and Reddy e t al Using a median sternotomy and cardiopulmonary bypass , both the R & L PAs and MAPCAs are unifocalized directly to the RVOT A valved conduit is used to reconstruct the atretic RVOT

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