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Assessment of operability of left to right shunts

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assessment of operability is crucial part of management in borderline PAH in congenital heart disease.

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Assessment of operability of left to right shunts

  1. 1. ASSESSMENT OF OPERABILITY OF LEFT TO RIGHT SHUNTS DR MAHENDRA JIPMER,CARDIOLOGY
  2. 2. INTRODUCTION • PAH associated with CHD remains a problem  Mainly in pts in whom the LR shunt wasn’t diagnosed until childhood or even adulthood  In patients who didn’t have access to cardiovascular care and surgical management as infants, particularly in developing countries
  3. 3. • The 2009 ESC/ERS/ISHLT guidelines on the management of PAH subdivided PAH-CHD into 4 clinical groups: (1) Eisenmenger syndrome (2) PAH associated with systemic-to-pulmonary shunts (3) PAH with small defects (4) PAH after surgical repair Eur Heart J 2009
  4. 4. Congenital Heart Disease (L-R shunts) and Pulmonary Hypertension Maurice Beghetti, and Nazzareno Gali, J. Am. Coll. Cardiol. 2009;53;733-740
  5. 5. • The response of the pulmonary vasculature to high pulmonary blood flow is however not uniform and does not occur in a predictable fashion
  6. 6. What determines the development of pulmonary vascular obstructive disease? Anatomy of defect Associated conditions Time Pre vs. post tricuspid Size Associated lesions: pulmonary venous hypertension Lungs and airways obstruction Altitude Syndromes: Tri-21 Unknown influences Genetic??? *
  7. 7. Large Fossa ovalis ASD SV ASD Unrestrictive VSD or PDA TruncusTGA VSD/PD A 100% Likelihoodofoperability Age Infancy Early childhood Adolescence Adulthood Defect vs. PVOD Risk
  8. 8. • Pre-tricuspid shunts: gradual increase in Qp as RV accommodates and enlarges – ASD, PAPVC, TAPVC* • Post tricuspid shunts: Direct transmission of pressure head: VSD (systolic), PDA, AP-Window (systolic and diastolic) • Pulmonary venous hypertension, associated mitral stenosis, other forms of LV inflow obstruction: – May introduce a substantial element of reversibility – May protect pulmonary vasculature from the effects of increased pulmonary blood flow???
  9. 9. Hypoxia elevates pulmonary vascular resistance • Diseases of pulmonary parenchyma • Airways (upper and lower) • Hypoventilation • High altitude Time • The likelihood of development of PVOD increases with time • The rate of increase in PVR varies depending on a number of influences
  10. 10. Risk of development of PVOD: Other (unknown) influences Remarkable individual variability • ASD with severe PAH in a child • VSD with shunt reversal in an infant • Operable AP window in a teenager • Operable large VSD in an adult Prediction for an individual patient is sometimes quite challenging
  11. 11. Deciding operability of L to R shunts • Clinical evaluation • Chest X-ray and ECG • Measurement of oxygen saturation • Echocardiography • Resting and post exercise ABG (PO2) • MRI • Cardiac catheterization
  12. 12. What principles govern decision on operability? • Post tricuspid shunts: Generally operable if there is evidence of a significant shunt in the basal state irrespective of PA pressure • Pre-tricuspid shunts: Pulmonary hypertension (anything more than mild) warrants concern especially if basal shunt is not obvious
  13. 13. Deciding operability: Principles • Age is an important variable and benefit of doubt must be given to younger patients. – E.g. a 1 year old with VSD and severe PAH where basal shunt is not obvious • Lung, airway and ventilation issues can elevate PVR and confound assessment • Pulmonary venous hypertension can result in reversible elevations in PVR
  14. 14. CLINICAL ASSESSMENT • Serial assessment by multiple experienced clinicians improves the reliability of clinical examination as a tool in determining operability • The presence of ‘clinical cyanosis’ or saturations <90% is a strong predictor of inoperability whereas the clear detection of a MDM on serial assessment strongly favours operability.
  15. 15. LV RVLA LV RA RV Clearly Operable: Cath not required
  16. 16. 26 year old Blue Single loud S2
  17. 17. Clearly Inoperable: Cath not required RV LV RA LA
  18. 18. ABG • The role of ABG measurement has not been adequately investigated • A decline in arterial PO2 after exercise may suggest fixed PVR as the fall in SVR during exercise is not balanced by a corresponding fall in PVR • Also allows assessment of respiratory function • The presence of ‘hypercarbia’ should alert the clinician to look for restrictive or obstructive pulmonary disease as a contributory factor to the PHT
  19. 19. Interventricular and Transductal velocity by Doppler • Clear understanding of the hemodynamics • Comprehensive clinical assessment • Influenced by the pulmonary artery and aortic pressures at the time of examination • Proper alignment is essential • Left parasternal view or high parasternal view for ductus; no ‘best’ view for VSD • Record peak systolic and end diastolic gradients in PDA
  20. 20. CORRELATION BETWEEN PREOPERATIVE HEMODYNAMICS AND CLINICAL OUTCOMES • The degree of individual variability makes it difficult to apply a single cut-off to determine operability Lopes AA, O’Leary PW. Cardiol Young 2009
  21. 21. PVR Estimation by Cardiac Catheterization Pulmonary artery mean pressure Pulmonary venous mean pressure Trans-pulmonary gradient PVR = Pulmonary blood flow Oxygen consumption PVO2 content PA O2 Content
  22. 22. • Operability is defined on the basis of the likelihood of a favorable vs an unfavorable outcome. • All the operability thresholds are defined to predict short- term success, which is immediate post-operative survival • Although these are the best current proposals on assessing operability in CHD and PAH, there is no consensus as to whether vasoreactivity testing is accurate enough to discriminate between patients who will or will not have a good long term outcome • Precise values of hemodynamic measures cannot be derived as individual patient factors such as cardiac lesion type and genetic predisposition may alter the hemodynamic testing or have an impact on outcome after surgical repair
  23. 23. • Hemodynamic assessment also aids in appropriate device selection • The fenestrated ASD device can be considered in selected pts • ASD or VSD device for patients with PDA and pulmonary hypertension instead of Amplatzer PDO
  24. 24. HOW USEFUL IS IT TO STUDY THE EFFECTS OF TEMPORARY SHUNT OCCLUSION? • ‘‘Responders’’ - 25% fall in PA pressures on balloon occlusion or a 50% fall in the ratio between pulmonary and aortic diastolic pressures • Pts with a high baseline PVR and low Qp/Qs ratio still may respond favorably to balloon occlusion and tolerate duct occlusion with normalization of PA pressures • Immediate fall in pulmonary pressures may not translate into long term benefits • The data available remains inconclusive and further clarification by studies with larger numbers is warranted.
  25. 25. LUNG BIOPSY • Used to be routinely done • Now less frequently done in clinical practice • The results aren’t sufficiently reliable and not without risk • Younger patients (<2 years of age) are often operable in spite of seemingly advanced changes on lung biopsy • Provides only one randomly selected area of the lung and does not represent a comprehensive evaluation of the nature and extent of lesions throughout the lungs
  26. 26. NOVEL MARKERS OF ASSESSING OPERABILITY BIOMARKERS : • ANP,BNP,Nt-pro-BNP,cardiac troponin T,uric acid,urinary prostaglandin metabolites,eNOS and dimethylarginines,ET-1 and ET-1:ET3 ratio,circulating VWF , cytokines (IL-1a, -2, -4, - 6, -8, -10 and 12p70, TNF-b, MCP-1 and osteopontin),CRP,pim-1 & HbA1c • Circulating endothelial cells and micro-RNAs
  27. 27. CONCLUSION • Determining operability is important in patients with left to right shunts who present late • A number of unresolved issues exist with currently available methods • A comprehensive assessment that incorporates clinical evaluation, noninvasive investigations and in selected cases, cardiac catheterization is needed • When in doubt, do not send patient for surgery • Efforts to evolve clear guidelines through careful prospective studies need to be undertaken

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