The document assesses the operability of left to right shunts and the implications of pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD). It outlines the challenges in determining operability and emphasizes the importance of comprehensive clinical evaluation, including various diagnostic tools like echocardiography and cardiac catheterization. Additionally, it highlights the need for clear guidelines and further studies to better assess individual patient outcomes and risks associated with surgery.

1. ASSESSMENT OF OPERABILITY OF
LEFT TO RIGHT SHUNTS
DR MAHENDRA
JIPMER,CARDIOLOGY

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. • 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. Congenital Heart Disease (L-R shunts) and
Pulmonary Hypertension
Maurice Beghetti,
and Nazzareno
Gali, J. Am. Coll.
Cardiol.
2009;53;733-740

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. 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. 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. • 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. 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. 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. 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. 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. 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. 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.

16. LV
RVLA
LV
RA
RV
Clearly Operable: Cath not required

17. 26 year old
Blue
Single loud
S2

18. Clearly Inoperable: Cath not required
RV
LV
RA
LA

21. 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

22. 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

23. 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

24. 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

25. • 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

27. • 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

28. 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.

30. 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

31. 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

32. 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