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Surgical Management of Pulmonary Atresiawith VSD and Major Aortopulmonary

Collateral Arteries

Yong Jin Kim, M.D.

Seoul National University

Children’s Hospital

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Morphology of PA+VSD, MAPCAMorphology 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

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Morphology of TOF with Congenital Pulmonary Artesia

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

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Morphology of Right & Left Pulmonary ArteryMorphology 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

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Surgical HistorySurgical 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

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Anastomosis of Systemic-Pulmonary Collaterals

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

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Alternative Sources of Pulmonary Blood FlowAlternative 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

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Natural HistoryNatural 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

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Clinical Features and Diagnostic CriteriaClinical 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

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Natural History of TOF with PANatural 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

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Nature of Pulmonary Blood FlowNature 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

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Principles of Surgical ManagementPrinciples 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

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Early Palliative ProceduresEarly Palliative Procedures

1. Goals 1) Create a balanced PBF 2) Incorporation & growth of PAs2. Procedures 1) Excessive blood flow Ligation Embolization Creating stenosis 2) Inadequate blood flow Systemic - pulmonary shunt RV - PA connection Unifocalization

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Advantages of RV - PA ConnectionAdvantages 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 e

valuation & intervention

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Histologic Characteristics of MAPCAsHistologic 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

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Techniques of UnifocalizationTechniques of Unifocalization

1. Direct anastomosis of collaterals1) Transplantation

2) Patch enlargement

3) Side by side anastomosis

2. Placement of interposition grafts1) Synthetic graft

2) Homograft

3) Xenograft pericardium

4) Autologous pericardium

5) Autologous artery or vein

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Ideal Unifocalization ProcedureIdeal 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

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Timing of UnifocalizationTiming of Unifocalization

1. At any age, when collaterals are large to allow technic

al ease without risk of thrombosis

2. Variable depending on collateral size, usually ol

der than 6- 12 months

3. Staged procedures may be required for the bilat

eral aortopulmonary collaterals

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Predictors of Successful Definitive RepairPredictors 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

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Selection for Final RepairSelection for Final Repair

1. Central combined Rt & Lt PA area at least 50~

75% of predicted normal

2. Distribution of unobstructed confluent PAs equival

ent to at least one whole lung

3. Presence of a predominant Lt to Rt shunt

without restrictive RV-PA connection

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Embryology of Systemic Collateral ArteriesEmbryology 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

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Connection of MAPCAsConnection 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

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Origin of MAPCAOrigin 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

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Characteristic Features of MAPCAsCharacteristic 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

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Causes of Lung Segments LossCauses 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

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Normal Intrauterine Development of Pulmonary Artery

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

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Advantages of One-stage Complete Repair

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

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Incremental Risk Factors forMortality and Morbidity

Incremental Risk Factors forMortality 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

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Disadvantages of Earlier RepairDisadvantages 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

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AR after Repair of TOF or PA,VSDAR 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

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Disadvantages of Multistage ApproachDisadvantages 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