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Surgical Treatment of PA with VSD without/with MAPCA

Surgical Treatment of PA with VSD without/with MAPCA. Jeong-Jun Park University of Ulsan, Asan Medical Center. Pulmonary Atresia with VSD without/with MAPCA. 1. Extreme subgroup of Tetralogy of Fallot 2. Major clinical problems in the arteries that

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Surgical Treatment of PA with VSD without/with MAPCA

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  1. Surgical Treatment of PA with VSD without/with MAPCA Jeong-Jun Park University of Ulsan, Asan Medical Center

  2. Pulmonary Atresia with VSD without/with MAPCA 1. Extreme subgroup of Tetralogy of Fallot 2. Major clinical problems in the arteries that supply the pulmonary circulation • 3. Variable clinical presentations & different • surgical strategies to that in TOF/PS

  3. Morphology of PA with VSD • The general morphology of the heart in TOF/PA • - Similar to that in simple TOF, • - The differentiating features are : • 1. No luminal continuity between RV & PA • 2. Pulmonary arterial anomalies • 3. Aortopulmonary collaterals

  4. Natural History Variable depending on the pulmonary blood flow - At birth, ductus dependent in case of true PAs - After ductal closure, dependent on the collaterals 1) Excessive pulmonary blood flow : CHF, PVOD 2) Moderate collateral stenosis : Balanced pulmonary blood flow 3) Severe collateral stenosis : hypoxia

  5. Patterns of Pulmonary Arteries

  6. Morphology of Pulmonary Artery • 1. Confluence of the pulmonary artery • 2. Stenosis of the pulmonary artery • 3. Distribution of the pulmonary artery • 4. Size of the pulmonary artery • 5. Abnormal hilar branching

  7. Alternative Sources of PBF • 1. MAPCAs • 2. Paramediastinal collateral arteries • 3. Bronchial collateral arteries • 4. Intercostal collateral arteries • 5. Collaterals from coronary arteries • 6. Iatrogenically aggravated collaterals

  8. Origin of MAPCA MAPCAs • - Variable in size, number, course, origin, arborization & histologic makeup • - Usually large & discrete arteries from 1 to 7 in number • 1. Majority from descending thoracic aorta 2. Some cases, from a common aortic trunk 3. Finally, from branches of aorta

  9. Influence of MAPCA 1. Chronic shunt & LV volume overload . Decrease LV function . Aortic annular dilatation . Aortic insufficiency 2. Segmental loss of lung parenchyme . In case of collateral stenosis --hypoxia . In unobstructed cases – CHF, PVOD

  10. Histologic Characteristics of MAPCAs 1. Extrapulmonary: muscular artery with well developed muscular media & adventitia 2. Intrapulmonary:medial muscle is gradually replaced by a thin elastic lamina resembling true Pas 3. Unobstructed MAPCAs: PVOD 4. Muscular segments of collaterals:prone to the development of severe stenoses, often progressive

  11. 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. PHT and progressive PVOD

  12. * Confluent PA

  13. Unobstructed MAPCA

  14. Long stenotic segment

  15. MAPCA = Dilated Bronchial Arteries - RCH, 2006 - All MAPCAs : anatomy similar to bronchial arteries - BAs: limited growth potential and vasoreactivity  might preclude long-term beneficial effects of unifocalization Bronchopulmonary shunts

  16. Definitive Repair of PA with VSD • Ultimate goal • : Completely separated pulmonary & systemic circulation • 1. Closure of ventricular septal defect • 2. Establish continuity between RV & PA • 3. Occlusion of redundant collaterals & shunts / Unifocalization

  17. Preparation for Definitive Repair 1. Maximize the pulmonary artery : The size & distribution 2. Maintain the adequate PBF 3. Avoid the excessive PBF

  18. Suggested Surgical Strategy for PA with VSD, MAPCA • 1. Unifocalization • - Staged vs one-stage • - Thoracotomy vs sternotomy • 2. Establishment of native PA growth • - With vs without unifocalization • 3. One-stage complete repair • 4. Repair without unifocalization

  19. Excessive blood flow Inadequate blood flow Early Palliative Procedures Goals 1) Create a balanced PBF • 2) Incorporation & growth of PAs - Systemic-pulmonary shunt - RV-PA connection : conduit or outflow patch - Unifocalization - Ligation - Embolization - Creating stenosis

  20. Ideal Unifocalization Procedure • Incorporation of all the nonredundant collaterals & true Pas  healthy microvasculature of lung 2. Use conduit that is growing, large, & minimizing the risk of thrombosis 3. Easily accessible from the mediastinum at the time of definitive repair

  21. 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 2~3 months 3. Staged procedures may be required for the bilateral aortopulmonary collaterals

  22. Techniques of Unifocalization • Procedures for collaterals 1) Ligation 2) Patch enlargement 3) Direct anastomosis 2. Interposition grafts 1) Synthetic graft 2) Homograft 3) Xenograft 4) Autologous tissue: pericardium, azygos v.

  23. Unifocalization Procedures • Ligation • Angioplasty • Anastomosis

  24. Unifocalization Procedures • Interposition • Additional PA creation • Central PA creation

  25. Surgical technique of unifocalization - Offbypass during dissection - Maximal use of native tissue - Avoid circumferential use of non-viable conduits for growth potential End-to side Side -to side

  26. Surgical technique of unifocalization Aortic button : several MAPCAs from the same location

  27. Surgical technique of unifocalization

  28. RV-PA Conduit

  29. Advantages of RV - PA Connection 1. Reduction of LV volume overload 2. Pulsatile blood flow to enhance PA growth 3. Facilitating the catheter access for the later evaluation & intervention ** CIx d/t 1) aneurysm and pseudoaneurysm 2) pulmonary flow and pressure is completely uncontrolled

  30. Melbourne Shunt Central end-to-side Aortopulmonary shunt Diminutive central pulmonary arteries

  31. Modified Central Shunt

  32. Criteria for VSD closure: 2 Dimensional Anatomic Data - Central PA area  50% of predicted normal - by Puga, 1989 - Predicted pRV/pLV  0.7, No MAPCAs remain More than 2/3 lung segments are centralized - by Iyer and Mee, 1991 - Nakata Index > 150mm2/M2 BSA -by Metras, 2001 - TNPAI  200 mm2/m2 - by Hanley, 1997 - 15 out of 20 bronchopulmonary segments(1 & 1/2 lungs) are connected to confluent pulmonary artery - by Baker, 2002

  33. Functional Intraoperative Pulmoanry Blood Flow Study * Post-repair RVSP: most reliable predictor of favorable outcome * Data of functionality of the entire pul. vasculature Hanley - m PAP < 25mmHg at a full flow(2.5L/min/m2) predicts RV/LV pressure ratio < 0.5 Toronto, 2009 • Close the VSD for a mPAP of <30mmHg • Predict postop. Physiology better than standard anatomic measures

  34. Functional Intraoperative PBF Study

  35. Repair without Unifocalization - RCH, 2009 - Unifocalization brings no long-term benefits . Unifocalization: sufficient to allow a safe repair but, failed to achieve adequate growth . Dilated BAs: limited growth potential & unstable • Growth of the native PA rather than recruitment of MAPCAs - Multi-stage approach . 4~6wks: Modified central shunt . 4~6months: RV-PA conduit . 3rd : complete repair or 2nd conduit • 18 pts enrolled in this protocol (No Unifocalization) . 7 : complete repair, RVP 59% of systemic . 8 : awaiting repair . 4 MAPCAs in 17 pts: ligated

  36. 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

  37. 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

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

  39. Conclusion - MAPCAs: Wide spectrum of pul. vascualr morphology and physiology, Ranging 1) from pts on the favorable end : true PAs with collaterals simply contributing systemic flow into the pul. vasculature 2) to pts on the unfavorable end : with completely absent native PAs and all of the pulmonary blood supply from collaterals  Management: complex and must be individualized according to their anatomy and clinical situations

  40. Predictors of Successful Definitive Repair 1. McGoon Ratio > 1 2. Nakata Index > 150mm2/M2 BSA(Metras, 2001) 추가하자 3. TNPAI > 200mm2/M2 BSA 4. Ideal Age : Notknown , but usually more than 2-3years old for conduit repair 5. 15 out of 20 bronchopulmonary segments(1 & 1/2 lungs) are connected to confluent pulmonary artery: Baker EJ. 2002

  41. 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

  42. Representative Data

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