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tetrology of fallot (TOF) with pulmonary atresia

TOF with PULMONARY ATRESIA
PULMONARY ATRESIA WITH VENTRICULAR SEPTAL DEFECT

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tetrology of fallot (TOF) with pulmonary atresia

  1. 1. Pulmonary atresia with Ventricular septal defect
  2. 2. tetralogy of Fallot = pulmonary arterial supply is derived from sys-to-pul collateral arteries
  3. 3. • extreme form of classic Tetralogy of Fallot.
  4. 4. • Type IV truncus and Pseudotruncus. •
  5. 5. Embryology Development of PA • MPA -septation of the truncus and aortic sac. • Intrapericardial RPA and LPA -sixth aortic arches with contribution from the aortic sac. • intraparenchymal pulmonary arteries - vascular plexuses of the lung buds. • Vascular plexuses =intersegmental arteries (ISAs) in the early embryonic period.
  6. 6. Embryology
  7. 7. Embryology • cephalad malalignment of the infundibular septum= anatomic obstruction of RVOT and a malalignment-type of VSD • aorta overrides VSD and is rotated in a counter- clockwise direction
  8. 8. Embryology • Pulmonary ostium becomses atretic much earlier in development , shortly after truncoconal partitioning but before closure of ventricular septum. ▫ PUL CIRCULATION is so heterogenous and highly variable with MAPCAS • PA-IVS-- PA Occurs much later after cardiac septation ▫ PDA, MPA, Confluent BPA, are well developed. No MAPCAS.
  9. 9. Environmental Factors • Maternal diabetes • Maternal PKU • retinoic acids • trimethadione
  10. 10. Epidemiology • 1.4% of CHD • 0.07 per 100 live births. • 26% - chromosomal abnormality/syndrome/single organ defects
  11. 11. DiGeorge syndrome and associated with Chromosome 22q11 microdeletion. ▫ VACTER ▫ CHARGE ▫ Alagille
  12. 12. 22q11 deletion • 10% -PA-VSD . • Right aortic arch, or aberrant subclavian artery -MC • Branch pulmonary arteries are smaller
  13. 13. NATURAL HISTORY • depends on the adequacy of pulmonary blood flow • duct-mediated pulmonary circulation -early mortality due ductal constriction and closure. • Half = die by 6 months • 90% die by 1 year of age
  14. 14. Adequate pulmonary blood flow - greater longevity Survival in to the sixth decade = multiple aortopulmonary collaterals.
  15. 15. median age at death = 11 months(9 days to 30 years) • 66% -alive at age 6 months • 50% alive by 1 year • 8% alive at age 10 years.
  16. 16. Pulmonary blood supply • RVOT-Infundibular atresia/ annular atresia • Extent of MPA atresia • Native pulmonary arteries • Source of pul blood ▫ PDA ▫ MAPCA ▫ Aquired collaterals ▫ AP window • Distal pulmonary vascular arborization
  17. 17. RVOT • Infundibular atresia- 70% •
  18. 18. RVOT • Anular aresia- thick fibrous membrane (analog of the pulmonary valve)
  19. 19. MPA • Extent of pulmonary valve atresia varies from only a plate-like atresia of the pulmonary valve to absence of both valve and a variable length of MPA. • Extension of MPA atresia to its bifurcation results in non-confluent central pulmonary arteries (PAs).
  20. 20. Right and Left Pulmonary Arteries • Presence or absence of confluent PAs = influences surgical outcome. • 20% to 30% == nonconfluent RPAs and LPAs. • Absence of the central portion of one or both of these arteries. • Confluent RPA and LPA - patent or atretic PT
  21. 21. PA Stenosis Stenoses of Origins of Pulmonary Arteries • confluence of the BPA and normal arborization of pulmonary arteries- 10% have stenosis of RPA, and 20% have stenosis of the LPA. • Stenoses are MC at the origin of PA on the side of PDA • juxtaductal stenoses (pulmonary artery coarctations) - 65%
  22. 22. PA Stenosis Stenoses beyond the origins of PA • small percentage • Localized areas of non compliance • May not present as stenoses until after a procedure that increases PBF
  23. 23. Somerville classification
  24. 24. Arborization of Pulmonary Arteries • frequent failure of the pulmonary arteries to distribute to all 20 pulmonary vascular segments. • Effected by ▫ Confluent central portions of pul arteries. ▫ Presence or absence of a PDA. • Pulmonary arterial segments that are not connected to a central pulmonary artery usually receive large AP collateral arteries.
  25. 25.  complete vascular distribution from native pulmonary arteries to 18 lung segments (considered to be complete arborization
  26. 26. inverse correlation between the number of lung segments supplied by collaterals and those supplied by the native PA.
  27. 27. Alternative Source of pulmonary blood ▫ PDA ▫ MAPCA ▫ Aquired collaterals ▫ AP window
  28. 28. PDA • undersurface of the arch -67% • undersurface of the innominate artery=33% • PDA = S shaped, long and arises at an acute angle from Aorta • Unilateral PDA =confluent Pas • PDA bilateral -- non-confluent PAs
  29. 29. • When PDA is present, PAs are confluent in 80% of cases. • PDA is absent in 1/3 of cases and is associated with absent central PAs.
  30. 30. Aortopulmonary collaterals (APCs) • differentiate them from the bronchial arteries • muscular arteries until they enter the lung parenchyma, the muscular layer is gradually replaced by elastic lamina that resembles true pulmonary arteries. • 30 – 65% • 2 – 6 in number.
  31. 31. Large Aortopulmonary Collateral Arteries • “large” -embryologic rather than acquired origin of the collaterals. • join an interlobar or intra-lobar pulmonary artery that arborizes normally within a pul- monary lobe or segment
  32. 32. origin of APCs include ▫ upper or mid-descending thoracic aorta= MC ▫ subclavian arteries ▫ abdominal aorta ▫ coronary arteries.
  33. 33. Three types of SCAs • Type I: Bronchial artery branches- from normal bronchial arteries. • Type II: Direct aortic branches- descending thoracic aorta. • Type III. Indirect aortic branches- from branches of the aorta other than bronchial artery-subclavian, IMA and intercostal arteries.
  34. 34. Morphology of Pulmonary Arterial Supply • Unifocal • Multifocal
  35. 35. Unifocal • If all intrapulmonary arteries are connected to unobstructed and confluent intrapericardial pulmonary arteries • confluence typically supplies all of both lungs
  36. 36. Unifocal • persistent PDA that provides unifocal PBF • rare for confluent pulmonary arteries feeding all of both lungs to be supplied by a solitary systemic-to-pulmonary collateral artery. • rare cases- APW , or via a fistula from the coronary arteries.
  37. 37. Multifocal • different parts of one lung are supplied from more than one source, • clinical complexity
  38. 38. Multifocal • multiple vessels feeding the pulmonary parenchyma - systemic-to-pulmonary collateral arteries. • hardly ever feed a lung that also receives supply via the PDA.
  39. 39. Various patterns of pulmonary arterial anatomy and source of blood supply
  40. 40. • PDA -- less reliable source beyond the first few days of life due to its tendency to close. • APCs are also prone for stenosis over a period of weeks to months but are more reliable than PDA
  41. 41. PDA VS MAPCAS PDA MAPCA’s ORGIN Opposite to LSCA DTA COURSE STRAIGHT TORTOUS/RETRO ESOPHAGEAL BRANCHING NO BRANCHING STENOSIS PA end AORTIC END DESTINY CENTRAL PA JOIN PA at HILUM / LOBAR/SEGMENTAL
  42. 42. Congenital Heart Surgeons Society Classification • Type A: Native PAs present, pulmonary vascular supply through PDA and no APCs. • Type B: Native PAs and APCs present • Type C: No native PAs, pulmonary blood supply through APCs only.
  43. 43. Coronary arteries • origin and distribution = normal • Conus artery =prominent. ▫ high origin of the coronary ostia, ▫ coronary-to-pulmonary artery fistulas, ▫ origin of the RCA from the left anterior aortic sinus, coursing across RV infundibulum
  44. 44. Clinical Features • cyanotic newborn • becomes increasingly hypoxemic as the ductus constricts. • If the ductus arteriosus remains patent or because systemic collateral vessels are sufficiently developed to provide adequate PBF -not severely hypoxemic.
  45. 45. • Hypoxemia and cyanosis increase as the patient “outgrows” the relatively fixed sources of PBF • If growth is delayed- 22q11.2 microdeletion. (growth failure due to heart failure caused by excessive pulmonary blood flow is uncommon)
  46. 46. Modes of presentation Cyanosis - 50% HF– 25% Murmur with mild cyanosis – 25%
  47. 47. Peripheral pulses • normal in the neonatal period(even with a PDA) • Beyond the first 4 to 6 weeks of age - if pulmonary blood flow is through a PDA or collaterals ,the pulses are bounding, and only minimal cyanosis is present.
  48. 48. • normal S1 • single S2 • systolic murmur – LLSB • not more than grade 3/6 in intensity • RVOT is atretic- no separate loud systolic ejection murmur at the upper left sternal border -
  49. 49. • PDA -continuous murmur after the first 4 to 6 weeks of life. • If MAPCA are present, continuous murmurs -multiple and prominent over the back (originate from the descending aorta)
  50. 50. ECG • RVH • RAD • Increased PBF---Bi BVHand left LAE
  51. 51. CXR • coeur en sabot ▫ levorotation of the heart, a prominent upturned cardiac apex, secondary to RVH ▫ concavity in the region of the MPA • right-sided aortic arch -(26% to 50% of these patients) ;TOF (20% to 25%).
  52. 52. • Pulmonary vascular markings - reticular pattern when there are multiple collaterals supplying the lungs. • Extent of pulmonary vascular markings will depend on the extent of PBF
  53. 53. Echocardiographic Features • PLAX-- large aortic valve that overrides a malaligned VSD • infundibular portion of the ventricular septum is anteriorly malpositioned. • TOF - patent, although hypoplastic, RVOT anterior to the infundibular septum with continuity with the main pulmonary artery. • infundibular septum is fused with the free wall
  54. 54. • Truncus arteriosus - resembles PA-VSD (in truncus arteriosus, the pulmonary arteries arise directly from the posterolateral aspect of the truncal root prior to the arch.)
  55. 55. • Suprasternal notch and high parasternal windows - size and status of the proximal PA. • malalignment VSD-membranous or infundibular • ASDs and additional muscular VSDs
  56. 56. • Short-axis parasternal and subcostal views- coronary artery abnormalities . • Color flow -right ventricular to pulmonary artery conduits
  57. 57. Cardiac Catheterization and Angiography • size and distribution of the true pulmonary arteries • extent of collateral blood supply
  58. 58. • large VSD- RV pressure is equal to LV pressure. • RVOT is atretic - catheter will not enter the pulmonary arteries from RV (manipulated from RV through the VSD into the aorta.) • Widened pulse pressure -large runoff into the lungs through a PDA or a previously constructed shunt.
  59. 59. • Ventricular and aortic root angiography • LV Ventriculography -LAXO view= middle portion and most of the upper interventricular septum tangentially. • Coronary artery anatomy -aortic root angiocardiogram and a 70-degree left anterior oblique view (with 20 degrees of cranial angulation).
  60. 60. Surgical importance - origin of the left anterior descending coronary artery from the right coronary artery=5% of patients
  61. 61. • Selective injections in the systemic-to-pulmonary collateral arteries - ▫ extent of the pulmonary arterial tree supplied by each collateral vessel ▫ type of pulmonary artery connection • Evanescent negative washout pattern -stream of unopacified blood from a connecting pulmonary artery flowing into an area of opacified pulmonary arterial tree(may be the only indication of an existing communication)
  62. 62. • If the central native PAs were not identified on echo- angiographically. • simultaneous contrast injection into the proximal stump of the pulmonary artery and the pulmonary vein wedge injection - length of discontinuity that need to be “bridged” surgically during repair
  63. 63. CT / MR angiography RVOT, MPA, branch PAs and APCs Needs lesser contrast.
  64. 64. Evaluation of adequacy of pulmonary arteries • Complexity of pulmonary blood supply determines the extent of surgical exploration necessary to perform unifocalization • Eligibility for complete repair - RV-PA conduit needs to be placed to the vessel which is connected to maximum possible pulmonary vascular bed • Closing the VSD at the time of placement of RV – PA conduit needs to be determined.
  65. 65. • Adequacy of the pulmonary vascular bed • pulmonary vascular resistance ▫ determinants of postoperative RV pressure = surgical outcome.
  66. 66. McGoon's ratio • dividing the sum of the diameters of RPA (at the level of crossing the lateral margin of vertebral column on angiogram) and LPA (just proximal to its upper lobe branch), divided by the diameter of aorta at the level above the diaphragm [D RPA + D LPA] / D TAO • average value of 2.1 is normal • Ratio above 1.2 -acceptable postoperative RV systolic pressure • . • Ratio below 0.8 - inadequate for complete repair of PA – VSD
  67. 67. Nakata index • diameter of PAs measured immediately proximal to the origin of upper lobe branches of the respective branch Pas • The sum of the cross sectional area (CSA) divided by the body surface area of • CSA of RPA (mm2)+ CSA of LPA (mm2)/ BSA (m2) • >150 mm2/m2 =complete repair without prior palliative shunt.
  68. 68. • Nakata index = widely used in preoperative assessment of adequacy of pulmonary vascular bed • Not useful in patients with multifocal pulmonary blood supply, who are evaluated for single-stage repair of PA - VSD. • Nakata index= no provision for the additional vascular bed that will be added by unifocalization
  69. 69. Total Neo-pulmonary artery index (TNPAI) • APCs index • addition of CSA of all significant APCs divided by the BSA • CSA of each APC is calculated from diameter of the respective vessels measured on preoperative cineangiogram
  70. 70. • sum of total APC index and PA index =TNPAI. • TNPAI index >200 mm2/m2 = low postoperative RV/LV pressure ratio and identified patients who were candidates for VSD closure at the time of single-stage surgicalrepair.
  71. 71. • limited value since they are based on the size of the proximal vessels only. • nature of the distal pulmonary vascular bed and pulmonary vascular resistance are not expressed in these calculations
  72. 72. Intraoperative method to assess the adequacy of pulmonary vascular bed
  73. 73. General principles of surgical therapy of PA-VSD • Connect as many lung segments as possible to the blood flow from RV during early infancy - to avoid significant histologic changes occurs in pulmonary vasculature
  74. 74. • ultimate goal - complete repair • 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 RV • central pulmonary artery size should be at least 50% of normal.
  75. 75. • At the end of operation, RVSP should be <70% that measured in LV • If higher, the ventricular septal defect is reopened.
  76. 76. • Complete repair - within weeks to months during infancy. • Therapeutic catheterization - balloon angioplasty help to rehabilitate pulmonary arteries with stenosis.
  77. 77. Components of surgical repair Unifocalization of APCs Placement of RV – PA conduit VSD closure. performed in one-stage/different operations depending on the anatomy and institutional policy.
  78. 78. RV – PA conduit placement • Cadaveric, cryopreserved homograft - right ventricle to available central pulmonary arteries. • complex cases, where a central pulmonary artery is absent or the pulmonary blood flow is multifocal- unifocalization of the diminutive native pulmonary arteries and APCs will be performed before RV – PA conduit is placed
  79. 79. Unifocalization of APCs Unifocalize significant APCs during the first 3 months of life • Median sternotomy - single stage repair • multi stage surgical approach- unifocalization is done through lateral thoracotomies. • unifocalization- APCs are ligated at the origin and mobilized to maximize their length . • Anastomosed in the mediastinum and connected to RV- PA conduit.
  80. 80. Aortic arch angiogram before (A) and main pulmonary arteriogram (B)after 1-stage complete unifocalization
  81. 81. VSD closure • at the time of initial repair / If any concerns about the adequacy of the pulmonary vascular bed- - -defer VSD closure. • Unrepaired VSD avoids supra-systemic RV pressure in the immediate postoperative period
  82. 82. Intraoperative method to assess the adequacy of pulmonary vascular bed • After completion of unifocalization and distal anastamosis of RV - PA conduit • perfusion cannula and a PA catheter are inserted from the proximal end of the conduit and left atrial vent is placed. • conduit is connected to the bypass machine. • bypass machine is run at increasing flow rates to 2.5 L/min/m2 and the PA pressure is monitored. • .
  83. 83. • VSD is closed if the mean conduit pressure is < 25 mmHg, and left open if it is higher. • < 25mmhg - Predict PRV/LV <0.5 following intracardiac repair
  84. 84. VSD closure • Alternative strategy - closing VSD with a fenestrated patch • fenestration =closed later either by surgery or transcatheter technique. • VSD closure is deferred at initial repair- surgically closed after 6 – 12 months- when left to right shunt is established via the VSD with Qp/Qs exceeding 2:1 by catheter evaluation .
  85. 85. Multi-stage versus single-stage approach
  86. 86. dependent on : ▫ Nature of PAs (small vs good size) ▫ Duct-dependent or collateral-dependent PBF ▫ Status of APCs ▫ Availability of surgical skills and results of the institution.
  87. 87. Multi-stage approach: • Traditional approach • palliative shunt in patients with good size, confluent central PA during neonatal period or early infancy to relieve cyanosis and allow for growth of distal pulmonary arteries. • diminutive PAs, RV – PA continuity is established by placing a RV – PA conduit
  88. 88. • VSD is typically left open at this first stage. • Unifocalization of APCs • subsequent surgery - ▫ VSD closure ▫ Relieve any residual RVOT obstruction ▫ Placement of a valved conduit.
  89. 89. Single-stage approach • APCs unifocalization and cardiac repair • median sternotomy
  90. 90. Comparison of outcome between multi and single-stage repair • Comparable
  91. 91. • Early 1-stage complete unifocalization ->90% of patients with pulmonary atresia and MAPCAs, and yields good functional results. • Complete repair during the same operation - two thirds of patients. • survival 3 years after surgery - 80%, and but there is a significant rate of reintervention. Circulation. 2000; 101: 1826-1832
  92. 92. Outcome of surgical repair • Early mortality - 4.5% • Late mortality - 16% • Ten- and 20-year survival - 86% and 75% • Freedom from reoperation of 55%.
  93. 93. Perioperative complications • Phrenic nerve injury-0.3 % • Reoperation for bleed-3% • Sepsis-5% • Heart block-0.5% • Pulmonary infarction-0.4%
  94. 94. Incremental Risk Factors for Death • PA Abnormalities • Age - > 5 to 8 years • Higher postrepair PRV/LV • Duration of CPB
  95. 95. Complementary role of interventional catheterization • Dilation of Distal stenosis within lung parenchyma (inaccessible to the surgeon. ) • Coil occlusion of APCs • Stent placement in RVOT • Palliative stenting of stenotic APC’S
  96. 96. Long term sequelae • palliative shunts- progressive cyanosis and polycythemia • AR • Deterioration of conduit and valve function -- loss of luminal diameter, calcification, peel formation • PR -- worsens with RV dilatation and dysfunction
  97. 97. Pulmonary venous wedge angiogram • TRUE PA in which there is low or no demonstrable prograde flow like PA
  98. 98. • End hole catheter is advanced from LA into pulmonary vein wedged forcefully, into distal capillary bed. • Shows pr wave of arterial contour.
  99. 99. • 0.3-0.4 cc/kg body weight of contrast material injected over a two second period. • forcefull hand injection/ by under pressure (less than 100 PSI). • Fallowed by 15ml of fush. • Progressive more force. • Until PA are visulized.
  100. 100. • Some times contrast extravasates into sarrounding tissue including bronchus • Pt may develop hemoptysis- self limiting
  101. 101. Use • caliber of the parenchymal pulmonary arteries • sizes at the hilum of the lung • presence or absence of a mediastinal confluence of pulmonary arteries. • Pr of PA(Aproximate).
  102. 102. THANK YOU

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