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Aortic Stenosis Audrone LaForgia, MD Advisor: Dr. Nelson CICU Lecture, 03/04/2011

Aortic Stenosis Audrone LaForgia, MD Advisor: Dr. Nelson CICU Lecture, 03/04/2011. Congenital Heart Disease Physiologic Presentations. Contractile dysfunction Obstruction of Systemic Blood Flow Ventricular Pressure Overload Ductal-dependant Systemic Blood Flow

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Aortic Stenosis Audrone LaForgia, MD Advisor: Dr. Nelson CICU Lecture, 03/04/2011

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  1. Aortic StenosisAudrone LaForgia, MDAdvisor: Dr. NelsonCICU Lecture, 03/04/2011

  2. Congenital Heart DiseasePhysiologic Presentations • Contractile dysfunction • Obstruction of Systemic Blood FlowVentricular Pressure OverloadDuctal-dependant Systemic Blood Flow • Volume OverloadLeft-to-Right Shunt/Excessive Pulmonary Flow • Obstruction of Pulmonary Blood FlowRight-to-left Shunt/Diminished Pulmonary Flow Ductal-dependant Pulmonary Blood Flow • TranspositionParallel Circulations • Single Ventricle Physiology

  3. Congenital Heart DiseasePhysiologic Presentations • Contractile dysfunction • Obstruction of Systemic Blood FlowVentricular Pressure OverloadDuctal-dependant Systemic Blood Flow • Volume OverloadLeft-to-Right Shunt/Excessive Pulmonary Flow • Obstruction of Pulmonary Blood FlowRight-to-left Shunt/Diminished Pulmonary Flow Ductal-dependant Pulmonary Blood Flow • TranspositionParallel Circulations • Single Ventricle Physiology

  4. Epidemiology • Defective development of cardiac valves occurs in 20-30% of patients with CHD • AS occurs in 3-6% of all patients with CHD • Male:female – 4:1 • Theory: diminished flow across AoV contributes to underdevelopment of the left heart (hypoplastic LV, aortic arch, etc.)

  5. Pathology • Valvar – 71% • Subvalvar – 23% • Supravalvar – 6%

  6. Pathology – Valvar AS • Bicuspid AoV - MC • Unicuspid AoV - less • Stenosis of tricuspid AoV – the least • Bicuspid AoV with fused commissure and an eccentric orifice; prone to calcification later in life

  7. Bicuspid AoV

  8. Bicuspid AoV

  9. Bicuspid AoV Echo

  10. Pathology – Subvalvar AS • Aka Subaortic stenosis • Simple diaphragm: • Aka Discrete membranous • 10% of all AS cases • 2/3 with associated cardiac lesions – VSD, PDA or COA

  11. Discrete Membranous Subaortic Stenosis

  12. Pathology – Subvalvar AS • Tunnel stenosis – long tunnel-like fibromuscular narrowing of the LVOT: • Often with hypoplasia of ascending aorta, AoV ring or thickened AoV leaflets • Extremely rare – 71 cases reported since 1961 • Usually associated with other LV anomalies – Shone complex: • Supramitral ring • Parashute MV • Subaortic stenosis • COA • Note associations above – secondary to decreased flow through the left heart

  13. Tunnel-like Subaortic Stenosis

  14. Pathology – Subvalvar AS • Hypertrophic cardiomyopathy (HCM), formerly known as Idiopathic hypertrophic subaortic stenosis (IHSS), – primary disorder of the heart muscle

  15. Pathology – Supravalvar AS • Annular constriction above the valve at the upper margin of sinus of Valsalva • May be associated with hypoplasia of ascending aorta • Often associated with Williams (or Williams–Beuren) syndrome

  16. Williams–Beuren syndrome • Developmental delay • Mental retardation • Pectus excavatum • Clinodactily • Characteristic (“elfin”) facies • Multiple PA stenoses • Initial hypercalcemia

  17. Pathology

  18. Closed Transventricular Aortic Valvotomy for Critical Aortic Stenosis in Neonates: Outcomes, Risk Factors, and Reoperations Brown JW et al. Ann Thorac Surg. 2006;81:236-242.

  19. Few Considerations • Critical AS with normal MV and normal-sized LV is much less common than with HLHS as it is a continuum – rationale for fetal intervention • Valvar AS is relatively common isolated defect, but it only occasionally presents as critical (symptomatic) in newborns; usually unicuspid AoV • LV dysfunction develops secondary to extremely high LV afterload

  20. Transition at Birth • During fetal life, obstruction to the left ventricle does not lead to decreased systemic perfusion as its outflow can be diverted via PDA • Left-sided obstruction causes decompensation after birth because postnatal changes in circulation prevent RV from performing the work of LV – FO closes

  21. After Birth • L to R shunt across FO is present due to increased diastolic pressure in LV; O2 Sat in RV and PA is increased as well as in PDA and systemic circulation • In critical AS R to L shunt across PDA is necessary to maintain systemic perfusion as there is no flow across AoV

  22. Pathophysiology - Decreased Systemic Perfusion

  23. Clinical Manifestations • Hemodynamic significance depends on degree of obstruction and tends to be progressive • Mild to moderate AS – asymptomatic • Severe AS – failure to thrive and tachypnea • Critical AS – CHF within the first few weeks (PDA dependent lesion)

  24. Differential Diagnosis • Decreased systemic perfusion: • Obstructive heart disease • Myocardial dysfunction from sepsis • Anemia/polycythemia • Hypocalcemia/Hypoglycemia/Metabolic acidosis

  25. Physical Exam – Critical AS • Stable during the first hours of life, or even until 3-4 weeks after birth • After ductal constriction CHF develops – poor feeding, pallor, diaphoresis, tachypnea, irritability – low CO/shock

  26. Physical Exam – Critical AS • Severe respiratory distress due to increased pulmonary venous pressure • Gallop rhythm - CHF • Peripheral pulses absent or weak • Poor perfusion • Hepatomegaly • Severe metabolic acidosis

  27. What About The Murmur? High pitch, grade 2-4/6 systolic ejection murmur is best heard at the right 2nd intercostal space, with radiation to the neck and apex In severe, but NOT critical AS as there is no flow across AoV in critical AS In general, SEM within the first 24 hours of life – think of AS or PS

  28. CXR – Critical AS • Cardiomegaly • Pulmonary venous congestion

  29. Management – Critical AS • Intubation/PPV • PGE1 at higher doses to reopen the duct • May need inotropes and diuretics for CHF • Percutaneous balloon valvuloplasty – optimal procedure for critically ill neonates – to relieve afterload

  30. Management • Medical • Surgical

  31. Medical Management • Percutaneous balloon valvuloplasty • Complications: • Transection of the femoral and iliac artery • Perforation of the aorta • Pericardial tamponade • Avulsion of AoV leaflet • Massive AR later – 10-30% • Perforation of MV or LV • Vascular complications more pronounced in neonates

  32. Surgical Management • Advantage – direct inspection of AoV, more precise commissurotomy, and shaving of any excess myxomatous tissue/nodules on the leaflets

  33. Surgical Management • Depends on LV function rather than size • Univentricular repair – if LV is severely fibrotic and unable to generate high pressures when obstructed, it may not be capable of supporting systemic blood flow even after obstruction is relieved: • Norwood procedure

  34. Surgical Management • Biventricular repair: • Close aortic valvotomy without CPB with dilators or balloon catheters • Aortic valve commissurotomy – divided within 1 mm of aortic wall; adequate leaflet attachments necessary to avoid AR • Aortic valve replacement • Tunnel-like subaortic AS – aortoventriculoplasty (Konno operation) • Discrete subaortic AS – excision of the membrane • Supravalvar AS – widening of stenotic area using a patch

  35. Closed Transventricular Aortic Valvotomy

  36. Aortic Valve Replacement • Mechanical valve • Porcine bioprosthesis • AoV allograft • Pulmonary valve autograft (Ross procedure) – autologous pulmonary valve replaces AoV; aortic or pulmonary allograft replaces pulmonary valve • Anticoagulation required for mechanical valves • Durability is an issue with allografts

  37. Neonatal Isolated Critical Aortic Valve Stenosis: Balloon Valvuloplasty or Surgical Valvotomy • Balloon valvuloplasty had higher re-intervention rate but shorter hospital and ICU stay, reduced immediate morbidity and was associated with less severe AR. Zain Z et al. Heart Lung Circ. 2006;15(1):18-23.

  38. Neonatal surgical aortic commissurotomy: predictors of outcome and long-term results • Predictors of increased mortality in neonates undergoing surgical valvotomy: • Size of aortic annulus • Endocardial fibroelastosis • Fractional shortening <35% • Low aortic gradient • Balloon valvuloplasty offers poor results when performed in patients with complex anomalies. Agnoletti G et al. Ann Thorac Surg. 2006;82(5):1585-92.

  39. In General… • Both surgical valvotomy and transcatheter balloon valvuloplasty are associated with mortality and morbidity and with residual or recurrent valve dysfunction. • Both are palliative procedures: sooner or later, re-intervention is likely. • The choice between the two varies according to the local expertise and/or preference.

  40. Most Important – Freedom Rate From Re-intervention • Balmer et al. showed that AR was frequently observed after balloon valvuloplasty; freedom rate from re-intervention was only 35% at 3 years. • At this age, there is no other choice than Ross procedure or AoV replacement by allograft. • Survivors after primary valvotomy in most surgical series have 10-year freedom rates from re-intervention between 55 and 90%. • At this interval, the AoV annulus is usually big enough to accommodate an adult-size mechanical valve, if needed.

  41. Therapeutic Dilemma • Newborn with severe, but NOT critical AS – no CV decompensation and LV function is normal • Demands on myocardium over the first weeks of life are large: • Increase in metabolic demand with growth • Decrease in Hb level – CO increases • Anemia causes systemic vasodilation - low DBP, tachycardia • Decrease coronary blood flow to hypertrophied LV • LV ischemia/dysfunction weeks after birth • May not recover after obstruction is relieved

  42. Neurodevelopment Albers EL et al. Pediatr Res. 2010;68(1).

  43. Thank You

  44. Bicuspid AoV Echo

  45. Physical Exam

  46. Ross-Konno procedure

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