1. SNUCH TS Surgical Management of Pulmonary Atresia with VSD and Major Aortopulmonary Collateral Arteries Yong Jin Kim, M.D. Seoul National University Children’s Hospital

2. SNUCH TS Morphology of PA+VSD, MAPCA 1. Concordant AV, VA connection,& VSD 2. Absence of continuity between RV & PA 3. Systemic-to-pulmonary collateral vessels 1 ) Bronchial artery branches 2 ) Collaterals from thoracic aorta 3 ) Collaterals from branches of aorta brachiocephalic, internal mammary, intercostal A

3. SNUCH TS Morphology of TOF with Congenital Pulmonary Artesia 1. No blood pass from RV to PA & consequently all pulmonary blood flow arises from the ductus arteriosus, collateral vessels, or fistulae 2. The pulmonary arterial anomalies are common 3. The aortopulmonary collaterals are common

4. SNUCH TS Morphology of Right & Left Pulmonary Artery 1. Confluence of the right and left pulmonary arteries Nonconfluence in 20-30% 2. Stenosis of the origins of the pulmonary arteries Stenosis of RPA origin in 10% Stenosis of LPA origin in 20% 3. Distribution of the pulmonary arteries Complete distribution more than half with confluence Incomplete distribution more than 80% with nonconfluence 4. Stenosis of the pulmonary arteries Juxtaductal stenosis in 60% 5. Size of the pulmonary artery 6. Abnormal hilar branching

5. SNUCH TS Surgical History History 1) Lillehi & Varco : 1st successful repair in 1955 2) Mayo clinic : Extracardiac conduit in 1965 3) Macartney : Constructive role of MAPCA in 1974 4) Alfieri : Describe the arborization pattern in 1978 5) Yamamoto : Closure of MAPCA by percutaneous catheter in 1979 6) Haworth, Macartney : Unifocalization concept in 1981 7) Lock : Dilation by percutaneous catheter in 1983

6. SNUCH TS Anastomosis of Systemic-Pulmonary Collaterals 1. Bronchial artery Enter true PAs within lung parenchyme 2. Collaterals from aorta Enter the hilum posteriorly with true PAs, or intraacinar vessels 3. Collaterals from branches of aorta Anastomosis with true PAs, or spread out over the surface of visceral pleura

7. SNUCH TS Alternative Sources of Pulmonary Blood Flow 1. Large MAPCA 2/3 in TOF with PA Rare in TOF with PS Stenosis of collaterals in 60% Enter in the hilum in 50% 2. Paramediastinal collateral arteries Arises from the subclavian arteries 3. Bronchial collateral arteries 4. Intercostal collateral arteries 5. Other collaterals Coronary arteries to bronchial arteries Coronary-pulmonary artery fistula 6. Iatrogenically aggravated collaterals

8. SNUCH TS Natural History 1. Variable depending on the pulmonary blood flow 2. At birth, pulmonary blood flow is ductus dependent in case of true PAs 3. After ductal closure, pulmonary flow is dependent on the collaterals 1) Excessive flow 2) Moderate collateral stenosis 3) Severe collateral stenosis

9. SNUCH TS Clinical Features and Diagnostic Criteria 1. No MAPCA or Fistulae Cyanosis is usual & depend on the ductal flow Becoming extreme as the ductus narrows 2. With large collaterals Rapid progression is modified PBF becomes large as neonatal PVR falls 3. Older age usually asymptomatic & become inadequate 4. Continuous murmur 5. Clinical presentation & studies are similar to TOF

10. SNUCH TS Natural History of TOF with PA 1. Confluent, normally distributing pulmonary segments & PDA At least 50%, Ductus tend to close, Without treatment, half are dead of hypoxia by 6 months and 90% by 1 year of age 2. Confluent, distributing to the majority of pulmonary segments About 25%, As ductus closes, cyanosis and symptoms may develop, depending on the number, size of collateral vessels Without treatment, one half by the age of 3 - 5 years, and 90% by the age of 10 years may die 3. Confluent or nonconfluent, distributing to the minority of pulmonary segments About 25%, With large AP collateral arteries supplying the majority Often large PBF flow early after birth, but rarely large to produce CHF Often they are very mildly cyanotic and good

11. SNUCH TS Nature of Pulmonary Blood Flow 1. Chronic shunt and LV volume overload Decrease LV function Aortic anular dilatation Aortic insufficiency 2. Hypoxia in case of collateral stenosis 3. Pulmonary vascular obstructive diseases

12. SNUCH TS Principles of Surgical Management 1. Ultimate goals 1) Close the VSD 2) Continuity between RV and PA 3) Close redundant collaterals & shunts 2. Preparation for definitive repair 1) Maximize size & distribution of PAs 2) Maintain adequate pulmonary blood flow 3) Avoid excessive pulmonary blood flow

13. SNUCH TS Early Palliative Procedures 1. Goals 1) Create a balanced PBF 2) Incorporation & growth of PAs 2. Procedures 1 ) Excessive blood flow Ligation Embolization Creating stenosis 2) Inadequate blood flow Systemic - pulmonary shunt RV - PA connection Unifocalization

14. SNUCH TS Advantages of RV - PA Connection 1. Reduction of Lt ventricle volume overload 2. Pulsatile blood flow to enhance PA growth 3. Facilitating the catheter access for the later evaluation & intervention

15. SNUCH TS Histologic Characteristics of MAPCAs 1. Muscular artery with well developed muscular media & adventitia before entering pulmonary parenchyme 2. Within the lung, medial muscle is gradually replaced by a thin elastic lamina resembling true PAs 3. Changes of pulmonary vascular obstructive disease in unobstructed MAPCAs

16. SNUCH TS Techniques of Unifocalization 1. Direct anastomosis of collaterals 1) Transplantation 2) Patch enlargement 3) Side by side anastomosis 2. Placement of interposition grafts 1) Synthetic graft 2) Homograft 3) Xenograft pericardium 4) Autologous pericardium 5) Autologous artery or vein

17. SNUCH TS Ideal Unifocalization Procedure 1. Incorporation of all nonredundant collaterals & true PAs 2. Use conduit that either growing, large, minimizing the risk of thrombosis 3. Easily accessible from mediastinum at the time of definitive repair

18. SNUCH TS Timing of Unifocalization 1. At any age, when collaterals are large to allow technical ease without risk of thrombosis 2. Variable depending on collateral size, usually older than 6- 12 months 3. Staged procedures may be required for the bilateral aortopulmonary collaterals

19. SNUCH TS Predictors of Successful Definitive Repair 1. McGoon Ratio Greater than 1 predicts successful repair 2. Nakata Index Greater than 150 predicts adequate 3. Ideal Age Not known, but usually until a patient is more than 2-3 years old for conduit repair

20. SNUCH TS Selection for Final Repair 1. Central combined Rt & Lt PA area at least 50~75% of predicted normal 2. Distribution of unobstructed confluent PAs equivalent to at least one whole lung 3. Presence of a predominant Lt to Rt shunt without restrictive RV-PA connection

21. SNUCH TS Embryology of Systemic Collateral Arteries 1. Bronchial arteries develop in 9th gestational week after intersegmental arteries resorbed 2. Aortic collaterals from intersegmental branches of dorsal aorta in 3~4th week of gestation 3. Aortic branch collaterals occur in later period

22. SNUCH TS Connection of MAPCAs 1. Connect outside the lung with central true PAs 2. Connect within the lung with lobar, or segmental PAs 3. Supply the lung independently without any connections

23. SNUCH TS Origin of MAPCA MAPCAs are usually large and discrete arteries from 1 to 7 in number & alternative sources of pulmonary blood flow. 1. Majority of MAPCAs from descending thoracic aorta, usually around Lt bronchus, or carina 2. Some cases, MAPCAs originate from a common aortic trunk 3. Finally, MAPCAs originate from branches of aorta

24. SNUCH TS Characteristic Features of MAPCAs 1. Variable in size, number, course, origin, arborization and histologic makeup 2. Various degree of PA hypoplasia, or even absence of the central PAs 3. MAPCAs connect with branches of central PAs, or constitute the only blood supply 4. Congenital or acquired discrete stenosis along the course of MAPCAs 5. Pulmonary hypertension and progressive PVOD

25. SNUCH TS Causes of Lung Segments Loss 1. Natural history often follows a course of progressive stenosis and occlusion 2. Inaccessible at the time of unifocalization procedure 3. Distal arterial hypoplasia and underdevelopment of preacinar, acinar vessels & alveoli 4. Iatrogenic occlusion, or with nonviable conduit 5. PVOD in their segments without obstruction

26. SNUCH TS Normal Intrauterine Development of Pulmonary Artery 1. Vascular plexus in the lung buds is connected to segmental arteries from the dorsal aorta 2. Intrapulmonary vascular plexus differentiates into segmental arteries by the 40th day 3. At that time, lung is perfused both by 6th aortic A & segmental arteries 4. Segmental arteries disappear by 50th day and parenchymal PAs & RV connected by central PA

27. SNUCH TS Advantages of One-stage Complete Repair 1. Eliminate the need for multiple operations 2. Eliminate the use of prosthetic materials 3. Establish the normal physiology early in life 1) Growth of respiratory & PA system 2) Avoid cyanosis & volume overload 3) Prevent the PVOD

28. SNUCH TS Incremental Risk Factors for Mortality and Morbidity 1. Younger age 2. Longer times of CPB 3. Greater number of collaterals 4. Absence of central pulmonary artery 5. Uncertain longterm fate of collaterals

29. SNUCH TS Disadvantages of Earlier Repair 1. Increased pulmonary morbidity 1) Contusion and congestion 2) Bronchospasm 3) Phrenic nerve injury 2. Magnitude of operation 3. Technically more demanding 4. Unknown ideal age

30. SNUCH TS AR after Repair of TOF or PA,VSD 1. Result of residual defects 2. History of endocarditis 3. Bicuspid or deformed aortic valve 4. Surgical damage to aortic wall & valve 5. Progressive dilatation due to increased flow 6. Intrinsic abnormality of aortic wall 7. Medial degeneration due to hemodynamic stress

31. SNUCH TS Disadvantages of Multistage Approach 1. The final repair is achieved on an old age 2. Mediastinum & hilar regions are significantly scarred, increasing surgical risks 3. Prolonged cyanosis & previous operation cause secondary collaterals, risks of bleeding 4. The risk of drop-off before the final repair