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Why Transposition of the Great Arteries is Destroying America and How to Make it Go Away

cordoc
April 09, 2016
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Why Transposition of the Great Arteries is Destroying America and How to Make it Go Away

cordoc

April 09, 2016
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  1. + The options were … n  why you should give

    up sex and devote your life to transposition of great arteries n  7 things lady gaga has in common with transposition of great arteries n  11 ways investing in transposition of great arteries can make you a millionaire n  guns don't kill people -- transposition of great arteries kills people n  what the government doesn't want you to know about transposition of great arteries
  2. + Definitions n The key anatomic characteristic of transposition complexes is

    ventriculoarterial discordance. n The aorta arises from the morphological RV n The pulmonary artery arises from the morphological LV
  3. + D-TGA (Complete) n  Atrioventricular concordance n  The aorta is

    anterior and to the right of the pulmonary artery n  60 % of TGA
  4. + L-TGA (Congenitally corrected) n  Atrioventricular discordance n  The aorta

    is anterior and to the left of the pulmonary artery
  5. + Anatomic Subtypes n (1) transposition of the great arteries with

    intact ventricular septum n (2) transposition of the great arteries with ventricular septal defect n (3) transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction n (4) transposition of the great arteries with ventricular septal defect and pulmonary vascular obstructive disease.
  6. + Coronary Artery Anomalies n  A left circumflex coronary arising

    from the right coronary artery (22%) n  A single right coronary artery (9.5%) n  A single left coronary artery (3%) n  Inverted origin of the coronary arteries (3%)
  7. + n  23 days gestation … the straight cardiac tube

    elongates and bends forming the cardiac loop. n  Cephalic portion bends ventrally, caudally, and right-ward. n  Caudal portion moves dorsally, cranially, and left-ward. n  The rotational motion folding over of the bulboventricular portion bringing the future ventricles side-by-side.
  8. + Embryology n 4th-7th weeks gestation … the heart divides into

    4 chambers via formation of swellings (cushions) of tissue that exhibit differential growth. n Endocardial cushions divide the AV canal forming the mitral and tricuspid valves. n Conotruncal cushions form the outflow tracts, aortic and pulmonary roots.
  9. + Embryology n 5th week gestation … the conotruncal cushions. n 

    Right superior truncal cushion grows distally and left- ward. n  Left inferior truncal cushion grows distally and right- ward. n  The net effect is a twisting motion. n  The truncal cushions fuse to form the truncal septum. n  Additional cushions develop in the conus which grow down and towards each other until they fuse with the truncal septum to form the RVOT and LVOT.
  10. + n Mechanism of great artery transposition n  Conotruncal cushion defect

    n  Leads to failure of the conotruncal septum to spiral and instead extends straight downward n  Aorta fuses with the RV and PA with the LV
  11. + Epidemiology n  ~ 0.8% of live births are complicated

    by a cardiovascular malformation*. n  > 750,000 adult patients with congenital heart disease. n  Transposition of the great arteries occurs in approximately 1 per 5,000 live births. n  More common in males n  Diagnosis possible in utero with fetal echocardiography n  Transvaginal ultrasound at 13-14 weeks (limited views) n  Transabdominal ultrasound at 16 weeks *not including bicuspid aortic valve and mitral valve prolapse
  12. + Complete transposition (D-TGA) n Pulmonary and systemic circulations are in

    parallel n Lethal, if no mixing (ASD, PDA, VSD) n ¾ are simple with no major associated abnormalities n ¼ are complex n  VSD (16%) n  Pulmonary/subpulmonary stenosis (9%) n  Coarctation of the aorta (4%)
  13. + Complete transposition (D-TGA) Clinical Presentation and Outcomes n Larger size

    and weight at birth n Dyspnea and cyanosis n Progressive hypoxemia n Congestive heart failure n Without treatment, the outlook is dismal n  30% mortality within the 1st week n  90% mortality within the 1st year
  14. + Complete transposition (D-TGA) Management n Prostaglandin E1 to maintain the

    PDA n Atrial septostomy (balloon or surgical) n  Palliative prior to corrective surgery n Repair within the first days to weeks of life n  2-4% mortality with 90% 1 year survival n  Atrial switch n  Mustard or Senning n  Arterial switch n  Rastelli procedure
  15. + Complete transposition (D-TGA) Atrial switch (Mustard/Senning) n  Developed in

    the 1950s n  Baffle directs venous return to contralateral ventricle
  16. + Complete transposition (D-TGA) Atrial switch (Mustard/Senning) n  Disadvantages n 

    RV functions as the systemic ventricle n  Several significant long term complications n  Congestive heart failure n  Arrhythmias n  Baffle leaks and obstruction n  Pulmonary hypertension n  Paradoxial embolus n  Endocarditis n  Overall survival 75% at 25 years n  Senning may be better than Mustard [Moons et al, Heart 2004] n  340 patients (~⅔ Senning) compared n  Less obstruction (1 vs. 15%) and better functional class with Senning n  No significant mortality benefit
  17. + Complete transposition (D-TGA) Atrial switch (Mustard/Senning) Arrhythmias n  Palpitations,

    presyncope, and syncope are common n  Both brady and tachyarrythmias frequently seen n  50% develop sinus node dysfunction n  Physical damage during surgery and baffle construction n  Disruption of blood supply leading to ischemia n  20% develop atrial flutter n  Sensitive to nodal agents due to conduction system disease n  11% required pacemakers at 20 years [Gelatt et al, J Am Coll Cardiol 1997] n  Pacemakers are difficult to place due to distorted anatomy n  Should be avoided if residual intracardiac communications due to risk of paradoxical embolus and stroke
  18. +Complete transposition (D-TGA) Atrial switch (Mustard/Senning) Congestive heart failure n 

    Baffle leaks (Mustard>Senning) n  Left-to-right shunts with pulmonary hypertension (7%) n  Risk of paradoxical embolus and stroke n  Indications for intervention include >1.5:1 left-to-right shunt or any right-to-left shunt n  Baffle obstruction (5-15%, Mustard>Senning) n  SVC > IVC manifesting as SVC syndrome or hepatic congestion/cirrhosis n  Often undetected due to collateral venous drainage (e.g. azygous vein)
  19. + n 40% develop right ventricular dysfunction n 10-40% develop 2+ or

    greater tricuspid (systemic AV valve) regurgitation n Annular dilatation from RV failure n Damage from surgery or endocarditis Complete transposition (D-TGA) Atrial switch (Mustard/Senning) Congestive heart failure
  20. + Complete transposition (D-TGA) Arterial switch n  Developed in the

    1980s n  Great arteries and coronaries are transected and re-anastamosed
  21. +

  22. + Complete transposition (D-TGA) Arterial switch n  Advantages n  LV

    is the systemic pump n  No disruption of atrial conduction (sinus rhythm) n  Fewer long term complications compared to atrial switch n  Coronary ostial stenosis n  Supravalvular pulmonary/aortic stenosis n  Intervention indicated for RVOT gradient >50 mmHg n  Neoaortic regurgitation n  Arrhythmias n  Follow up with normal LV function and good exercise capacity
  23. + Complete transposition (D-TGA) Rastelli procedure n TGA with VSD and

    LVOT obstruction n Outcomes n  RV-PA conduit obstruction n  Exercise intolerance/angina n  RV failure n  Intervention for RV-PA gradient >50 mmHg n  LV-Ao patch obstruction n  Dyspnea or syncope
  24. + Complete transposition (D-TGA) RV Failure after Atrial Switch n Standard

    heart failure therapies are unproven n The two-stage arterial switch n  Stage 1 – the PA is banded to ‘re-train’ the LV to handle systemic pressures n  Stage 2 – the atrial baffles and pulmonary band are taken down and an arterial switch is performed n 50% survival at 8 years in early results n  Appears to be more successful in patients under 12
  25. + Congenitally corrected transposition (L-TGA) n A rare disorder that may

    present in adulthood. n Associated anomalies (95% of patients) n VSD (75%, commonly perimembranous) n Pulmonary stenosis (75%, commonly subvalvular) n Tricuspid valve anomalies (>75%) n Congenital complete heart block (5%)
  26. + Congenitally corrected transposition (L- TGA) Outcomes n Arrhythmias n Abnormal AV

    node and His positions n Dual AV nodes n 2% per year incidence of complete heart block n  Susceptible to fibrosis of conduction system n Median survival 40 years n Mortality from progressive RV failure or arrhythmias n  Tricuspid regurgitation is major predictor
  27. + Echocardiography Segmental approach to congenital heart disease 1.  Position

    of the apex 2.  Situs of the atria n  Morphological atria based on anatomic appearance of their appendages n  75% concordance with abdominal situs (aorta and IVC positions) 3.  Atrioventricular relationship n  Differentiate the morphological RV from LV: 1.  Trabeculated apex 2.  Moderator band 3.  Septal attachment of the tricuspid valve 4.  Lower (apical) insertion of the tricuspid valve 4.  Ventriculoarterial relationship n  Pulmonary artery is distinguished by its early branching pattern n  Curved contour of the aortic arch with three major branches
  28. + Echocardiography Complete Transposition with Atrial Switch n Systemic hypertrophied RV

    septum bows into LV n May impact TR and enhance subpulmonary stenosis
  29. + Echocardiography Complete Transposition with Atrial Switch n Aortic and pulmonic

    valves lie in the same plane n Aorta is anterior and to the right (parasternal short axis)
  30. + Echocardiography Congenitally Corrected Transposition n Hallmark is reversed offsetting of

    the AV valves n Aorta is anterior and to the left (parasternal short axis)
  31. + Echocardiography Special Considerations n  Atrial switch n  RV function

    n  Tricuspid regurgitation n  Subpulmonary obstruction n  Baffle leak or obstruction (color Doppler) n  Normal baffle flow is phasic with peak velocity <1 m/sec n  Arterial switch n  Neoaortic valve regurgitation n  Supraneopulmonary valve stenosis n  Wall motion abnormalities due to coronary artery ostial stenosis n  Rastelli procedure n  LV-Ao tunnel patch obstruction n  RV-PA conduit degeneration (stenosis/regurgitation)
  32. + Echocardiography Special Techniques n Index of myocardial performance n dP/dT from

    tricuspid regurgitant velocity n Isovolumic myocardial acceleration n Tissue Doppler measurement of myocardial acceleration during isovolumic contraction n ?sensitive assessment of RV contractility that is less load dependent
  33. + Endocarditis Prophylaxis ACC/AHA 2008 Guidelines state that antibiotic prophylaxis

    is reasonable to consider for patients at the highest risk of adverse outcomes (Class IIa) n  Prosthetic valves n  Prior endocarditis n  Congenital heart disease n  Unrepaired cyanotic, including palliative shunts and conduits n  Completely repaired with prosthetic material or device (6 months) n  Repaired with defects at or near a prosthetic device n  Post-cardiac transplant with valvular disease
  34. + References n  Webb et al., Congenital Heart Disease in

    Braunwald’s Heart Disease, 8th ed., Chapter 61, 1561-1624. n  Sadler, Cardiovascular System in Langman’s Medical Embryology, 8th ed., Chapter 11, 208-259. n  Otto, The Adult with Congenital Heart Disease in Clinical Echocardiography, 4th ed., Chapter 17, 418-447. n  Warnes, Transposition of the Great Arteries, Circulation 2006 114:2699-2709. n  Love et al., Evaluation and Management of the Adult Patient with Transposition of the Great Arteries Follow Atrial-level (Senning or Mustard) Repair, Nature Clinical Practice Cardiovasc Med 2008 5:454-67. n  Verhuegt et al., Long-term Prognosis of Congenital Heart Defects: A Systematic Review, Int J Cardiol 2008 131:25-32. n  Skinner et al., Transposition of the Great Arteries: from Fetus to Adult, Heart 2008 94:1227-35 n  ACC/AHA Guidelines for the Management of Adults with Congenital Heart Disease, J Am Coll Cardiol 2008 52:e1-121. n  Images courtesy: Langman’s and Braunwald’s