This document discusses the normal anatomy and physiology of the pulmonary circulation and how it changes after birth. It describes the different types of pulmonary arteries and veins and their structures. After birth, pulmonary vascular resistance decreases significantly due to various factors, reaching adult levels by 6-8 weeks. The document also discusses the classification of pulmonary hypertension and different stages of vascular changes seen in conditions like congenital heart disease. Right heart catheterization is important to assess the severity of pulmonary hypertension and determine operability of patients for surgery.

1. Dr. K.Nagendra prasad

2. Normal Anatomy of the Pulmonary Circulation
 The lung has a unique double arterial blood supply from the pulmonary
and bronchial arteries, as well as double venous drainage into the
pulmonary and azygos veins.
 Pulmonary arteries:
 Elastic: conducting vessel, ≥ 500 μm, highly distensible
 Muscular: 100-500 μm, no elastin, non distensible
 Arterioles: ≤ 100 μm, thin intima and single elastic lamina
 Bronchial arteries: nutrition to the airways
 wide and thin-walled vessels - high flow , low pressure and low resistance
circulation.
 The normal pulmonary vascular bed offers less than one-tenth the
resistance to flow offered by the systemic bed.

4. CHANGES AFTER BIRTH
 The pulmonary circulation undergoes important physiologic and
anatomic changes in the first hours, weeks, and months of life.
 In utero, the pulmonary arteries are relatively thick walled, and
pulmonary vascular resistance is very high, limiting pulmonary blood
flow to less than 10% of combined right and left ventricular output.
 At birth PBF increases 8-10 times with a fall in pulmonary pressure to
a level less than 50% of systemic pressure.
 Reason - the combined effects of mechanical expansion of the lung,
increased oxygen tension, and shear stress lead to an increase in
prostacyclin and nitric oxide (NO) synthesis and to the release of
humoral substances such as bradykinin and adenosine.
 By 6 to 8 weeks, pulmonary vascular resistance usually has reached a
normal adult level of 1 to 3 Wood units

5. GROWTH AND REMODELLING OF NORMAL PUMONARY
VASCULAR BED WITH AGE

9.  Stage I - Medial hypertrophy (reversible)
 Stage II - Cellular Intimal hyperplasia in a abnormally
muscular artery (reversible)
 Stage III - Lumen occlusion from intimal hyperplasia of
fibroelastic tissue (partially reversible)
 Stage IV - Arteriolar dilation and medial thinning
(irreversible)
 Stage V - Plexiform lesion, which is an angiomatoid
formation (terminal and irreversible)
 Stage VI - Fibrinoid/necrotizing arteritis (terminal and
irreversible
Heath-Edwards Classification
Rever
sible
Irre
vers
ible

12. Rubinovitch classification –
morphometric changes in lung biopsy
Grade Peripheral arteries Medial
thickness(muscular
arteries)
Arterial
concerntration
Grade A Muscle extened
into peripheral
arteries
<1.5 times N
NormalGrade B ( mild ) Increased
extension
1.5 to 2 times
Grade B (severe) > 2 times N
Grade C Arterial
concerntration
and size reduced

13. GRADE PULMONA
RY BLOOD
FLOW
Mean PA
pressure
PVR WEDGE
ANGIOGR
AM
HEATH
EDWARD
GRADE
A INCREASE normal TAPERING
OF AXIAL
ARTERIES
I
Mild B INCREASE <50% ABRUPT
TAPERINGSEVERE B >50% of
Systemic
pressure
C DECREASE Supra
systemic
pressure
>3.5 WU VERY
ABRUPT
TAPERING
Common
with II & if
arterial
concentrati
on <50% of
normal - III

14. higher preoperative pulmonary/systemic arterial pressure (Pp/Ps) and
resistance (PVR/SVR) ratios are associated with more advanced stages of
pulmonary vascular disease on lung biopsy and a higher incidence of
early and late postoperative pulmonary hypertension.
Early Post operative PA pressure
Grade A & mild grade B Normal / mild elevation
Severe grade B & Heath Edward grade I elevated
Grade C & Heath–Edwards II and III very high

15.  Correlation between biopsy grade with pulmonary vascular
resistance 1 year after cardiac repair :
1 . Patients operated within the first 8 months of life tend to have normal
pulmonary hemodynamics regardless of the severity of vascular
changes on lung biopsy, as do patients with severe grade B (Heath–
Edwards I) abnormalities, regardless of their age at repair.
2. Patients surgically corrected between 9 months and 2 years of life with
grade C and Heath–Edwards II or III structural changes may have
persistent elevation in pulmonary vascular resistance . So corrective
surgery is deferred.
3. Patients operated after the age of 2 years - persistent elevation in
pulmonary vascular resistance

16.  severe grade B, or grade II changes in any vessel may preclude a
favorable result from a Fontan procedure.
 Even mild grade B changes also associated with increased morbidity
after the Fontan procedure, as gauged by prolonged hospitalization;
the need for increased ventilator support; and drainage from chest
tubes.

17.  This relationship however is neither constant nor predictable and the
degree of individual variability makes it difficult to apply a single cut-
off to determine operability in these patients.
 Situation like for younger patients (<2yrs) are often operable in spite of
seemingly advanced changes on lung biopsy.

18. Pulmonary wedge angiography
 For the right-sided angiogram, a
5F or 6F pulmonary wedge
catheter was placed in the lower
lobe to a level one rib space
below the takeoff of the right
pulmonary artery.

19.  For the left-sided studies, the catheter was placed two rib spaces below
the takeoff of the left pulmonary artery.
 After the catheter was positioned, the balloon was inflated and contrast
material was injected at a dose of 0.3 ml/kg (minimum 2 ml).
 Injections were by hand as this was thought to be safer and simpler.
 Changes that can be evaluated quantitatively are –
 1. Sparsity of arborization of the pulmonary tree,
 2. Abrupt termination, tortuosity and narrowing of small arteries, and
 3. Reduced background capillary filling.

20. Analysis of the Angiogram
 AP view
 Maximum expiration
 The rate of tapering of the arteries is assessed by measuring the length
of a segment over which the lumen diameter narrows from 2.5 mm to
1.5 mm.

21. Rate of Tapering

22.  Background Haze :
 The degree of filling of small peripheral arteries that determines the
background haze.
 Reduced background haze in patients with PAH.

23.  Pulmonary Circulation Time:
 Pulmonary circulation time as the transit time of the contrast material
through the capillaries and veins.
 Longer the circulation time severe the pulmonary vascular disease.
 Assessment of the circulation time depends on the exclusion of
pulmonary vein stenosis and intrapulmonary shunting.

24. LIMITATIONS
 Pulmonary stenosis or previous placement of a pulmonary artery band,
will give the impression of rapid tapering.
 With advanced vascular disease, there is sometimes such extensive
intimal hyperplasia that the vessel appears narrowed all the way from
the hilum so that abrupt tapering is no longer apparent.

25. DEFINITION
 Pulmonary hypertention is
defined as a mean pulmonary
artery pressure (PAP) greater
than 25 mm Hg at rest.
 A mean PAP of 8 to 20 mm Hg
at rest is considered normal.

26. CLASSIFICATION OF PULMONARY
HYPERTENSION
 Dana Point classification(2008) is modified by Pediatric
Task Force of the 5th World Symposium on Pulmonary
Hypertension (WSPH) in Nice, France (2013).

29.  PULMONARY HYPERTENSION in patients with increased pulmonary
blood flow
 PULMONARY HYPERTENSION in SINGLE VENTRICLE
PHYSIOLOGY
 EISENMENGER SYNDROME MANAGEMENT
 CHILD WITH IDIOPATHIC PULMONARY HYPERTENSION

31.  Basic concepts – Types of lesions , factors that determine development
of pulmonary hypertension
 What are the indications to perform catheterization?
 How do we decide on operability of L-R shunts ?
 What are the limitations of the tools that we have with us?

32.  LEFT-TO-RIGHT SHUNTS :
 Ventricular septal defect
 Atrioventricular septal (canal) defect
 Patent ductus arteriosus
 Atrial septal defect
 Aortopulmonary window
 PALLIATIVE SHUNTING
OPERATIONS :
 Waterston anastomosis
 Potts anastomosis
 Blalock–Taussig anastomosis
 CYANOTIC HEART DISEASE :
 Transposition of the great arteries
 Truncus arteriosus
 Tetralogy of Fallot (pulmonary
atresia/VSD)
 Univentricular heart (high-flow)

34. AGE
TYPE of
LESION
Development
of pulmonary
hypertension

35. AGE
 In general, patients with a VSD or patent ductus arteriosus do not
develop irreversible pulmonary vascular changes before 2 years of age.
 Patients with an ASD are less likely to develop severe PAH, and this
usually occurs in the third to fifth decade.
 Patients with cyanotic congenital cardiac lesions such as transposition
of the great arteries, truncus arteriosus, and univentricular heart with
high flow are more likely to develop rapid irreversible pulmonary
vascular disease by 1 yr of life.

37. Pre Tricuspid vs Post Tricuspid
 Pre-tricuspid shunts: Gradual increase in Qp as RV
accommodates and enlarges – ASD, PAPVC, TAPVC
 Post tricuspid shunts: Direct transmission of pressure head to
pulmonary vasculature: VSD (systolic), PDA, AP-Window (systolic and
diastolic) – early development of pulmonary hypertension.

39. Confounding factors that are associated with development of
pulmonary hypertension in patients with left to right shunts -
 Pulmonary venous hypertension, associated mitral stenosis, other
forms of LV inflow obstruction causes early development of
pulmonaryhypertension.
 Left heart diseases like systolic and diastolic dysfunction due to
associated cardiomyopathy.
 Hypoxia due to Diseases of pulmonary parenchyma, Airways (upper
and lower), Hypoventilation, High altitude can elevates pulmonary
vascular resistance.

41.  On the basis of hemodynamic findings, three different groups of
patients, may present with pulmonary arterial hypertension associated
with congenital cardiac shunts:
 1)OPERABLE : patients with increased pulmonary blood flow and low
pulmonary vascular resistance.
 2)INOPERABLE : patients with Eisenmenger physiology and advanced
pulmonary vascular disease.
 3) BORDERLINE pulmonary vascular resistence

43.  Postexercise saturation of < 90% was considered as being suggestive of
irreversible PVR and when saturation was between 90% to 95%, they
were subjected to cardiac catheterization.

44. (1) Right heart catheterization is necessary to confirm the diagnosis of
PH and accurately determine the severity of the hemodynamic
derangements.
(2) Helps to exclude patients with PH due to left heart disease, such as
systolic dysfunction, diastolic dysfunction, or valvular heart disease.
(3) to assess operability as part of the assessment of patients with systemic
to pulmonary artery shunts.
Cardiac Catheterization

45. PRECAUTIONS WHILE DOING CATH
 Polycythemia
 PCV of >65% =Phlebotomy (O-D/O x wt x70)
 Anaemia
 Appropriate Hb =38 –(0.25 xSaO2)
 Contrast use
 Less than 4ml/kg
 complication rates are 0% to 1%,
 Risk of cardiac arrest is 0.8% to 2%, and
 Risk of PHCs is 5%.

46.  Need for either conscious sedation or general anesthesia in children .
 Drugs with minimal effects on the PA pressure and PVRI in children
include fentanyl, ketamine, and propofol.
 Avoid systemic hypotension, particularly in patients with marked
elevation of PAP with low cardiac output.
 Monitor ABG during procedure - Acidosis is a powerful pulmonary
vasoconstrictor, and alkalosis is a vasodilator.
 Hypoxia causes vasoconstriction, whereas hyperoxia causes
vasodilatation .

47. VASODILATOR AGENTS
 100% oxygen , inhaled NO , iv isoprenaline , iv prostacycline and
adenosine .
 pit fall in using 100% oxygen for caliculation of flow and resistence : -
dissolved oxygen content increased when 100% oxygen is used. So if it
is not taken in to consideration the caliculated value showed as false
low.

49.  Adenosine and epoprostenol possess potent inotropic properties
leading to An increase in cardiac output with no change in PAP which
result in a reduction in calculated PVR and may be erroneously
interpreted as a vasodilator response.
 NO has little effect on cardiac output.
 The initial dose is usually 20 ppm with 21% oxygen , if require we can
use up to 80 ppm.
 Major problem - non availability and protocol for dosage and duration
of NO inhalation is not standardized.

51.  The algorithm is not applicable to complex conditions
such as the absence of a subpulmonary ventricle
(candidates to cavopulmonary anastomoses).

52. Lopes and O’Leary criteria for operability :
 A decrease of 20% in the PVR index
 A final PVR index <6 Wood units ¥ m2
 A decrease of about 20% in the ratio of PVR:SVR
 A final ratio of PVR:SVR <0.3.

53. Other criterias that predict good
response following surgery
 Rp/Rs absolute value <0.33 or fall of >10% from base line following
inhaled NO (iNO) + oxygen.
 TPR (defined as mean PAP/pulmonary flow index) <15 U × m2 has
highest correlation.

54. PITFALLS
 Hemodynamic evaluation of these patients is a “snapshot” that may not
represent the usual state of the patient.
 These studies are frequently performed under general anesthesia which
frequently leads to a lower systemic blood pressure than exists in the
pre-catheterization condition
 The LaFarge equation introduces significant overestimation of oxygen
consumption in ventilated patients with CHD of all ages, particularly
in children younger than 3 years.
 Estimation rather than measurement of PaO2 in the pulmonary veins
leads to overestimation of pulmonary blood flow, and subsequently
underestimation of the PVR.

55. What else can be done in the
cath lab?
 Test occlusion of the defects:
 ASD
 PDA
 Any fall in systolic PAP of > 20% of the baseline pressure was
considered as an indicator of significant left to right shunt across duct
contributing to PHT.
 Responders - >25% fall in PA pressures on balloon occlusion or a >
50% fall in the ratio between pulmonary and aortic diastolic pressures.
 Little validation with long term data
 Immediate reduction of PA pressure may not translate into
long term benefits.

57. TREAT & REPAIR strategy
 For PAH-CHD patients in the grey zone of PVRI estimation (6–8
WU×m2, figure 1), medical treatment prior to closure of the shunt
defect may be pursued, and closure of the defect can be considered if
in a subsequent haemodynamic study the PVR index is < 6 WU×m2.
 If the patient remains in the grey zone of indexed PVR, a modified
surgery with, for example, fenestrated defect closure may be
considered.
 Convincing longterm data for this strategy remain scarce.

58.  Lung biopsy for the histopathological evaluation of changes to the
pulmonary vasculature used to be routinely used to assess operability.
 But this is now less frequently done in clinical practice, as the results
aren’t sufficiently reliable and associated with risk, and it 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.
 Some patients develop advanced PVD although histology suspected
mild lesions, while PAH and lesions are often reversible in infants and
young children after surgical repair of CHD, despite advanced changes
on biopsy.

61. Single ventricle :
 Norwood/Damus Stansel Kaye
 Cavopulmonary anastomosis (Glenn)
 Fontan procedure

62.  After cavopulmonary surgery, systemic venous return drains directly
into the pulmonary arteries, and the pulmonary circulation(non
pulsatile flow) is without a dedicated subpulmonary ventricle.
 The systemic and pulmonary circulations are in series, and pulmonary
blood flow is dependent on the transpulmonary gradient and kinetic
energy imparted by systemic ventricular contraction.

63.  So In patients with a single ventricle with bidirectional cavopulmonary
anastomosis, due to nonpulsatile flow to the pulmonary arteries & the
PAP is measured with less than a full cardiac output, PAP may not be
>25 mm Hg inspite of significant pulmonary vascular disease.

64.  In Single Ventricle physiology PAH is defined as PVRI > 3WU and
Trans pulmonary gradient (TPG) > 6mmhg .
 Presence of PH predicts high risk for poor outcomes in these patients.

65.  Problems in estimation of pulmonary blood flow and PVR
after cavopulmonary anastomoses :
 These include poor reliability of pressure measurements in a
nonpulsatile system, sampling a true pulmonary artery saturation in
the presence of aortopulmonary collaterals or residual forward flow
from the ventricles, and the effect of venous collaterals or arteriovenous
malformations that “steal” blood flow from the pulmonary circulation.

66.  If the measurements are beyond these limits, pre-treat the patient with
vasodilators such as PDE5-inhibitors or endothelin receptor antagonist
to decrease PVR with the intention to reach the criteria for
TCPC/Fontan palliation.
However, clinical efficacy of such pharmacotherapy has not been proven.

67. MANAGEMENT OF PH IN POST OPERATIVE STATE
 In the acute, post-operative phase, patients with increased PVR are
treated with nitric oxide and supplemental oxygen.
 Prostacyclins have been rarely used in perioperative Fontan patients.
 Bosentan improves exercise tolerance and oxygen saturation in some
patients with impaired hemodynamics after Fontan surgery.
 Sildenafil is not approved for post operative patients and there are no
published data to support its efficacy or safety in this indication.

68. MANAGEMENT IN FAILING FONTAN
Low cardiac output, excessive hypoxemia, or protein loosing enteropathy may
all be clinical manifestations of increased PVR in failing fontan patients.
 Treatment of late Fontan patients with inhaled nitric oxide reduces PVR,
although it has no significant effect on cardiac index.
 A single dose of sildenafil has been shown to improve exercise capacity and
hemodynamic response to exercise in late, nonfailing Fontan patients.
 There are currently no data on the effectiveness of prostanoid therapy in
the failing Fontan.
 Long-term treatment with bosentan improved symptoms, WHO
functional class, maximal and sub-maximal exercise capacity, mean PAP,
pulmonary blood flow and PVR in a patient with plastic bronchitis
following Fontan.

70.  Paul Wood, in 1958, used the term Eisenmenger complex to define the
condition of a large VSD associated with increased PAP and resistance
causing bidirectional or reversed (right-to-left) shunting and systemic
oxygen desaturation.
 Eisenmenger syndrome is defined as pulmonary hypertension at
systemic level due to a high pulmonary vascular resistance with
reversed or bidirectional shunt through a large VSD or any other
systemic to pulmonary circulation.

71. Hemodynamically,
 Eisenmenger syndrome (ES) is defined as an elevation of the
pulmonary vascular resistance to 12 Wood Units or to a pulmonary-to-
systemic resistance ratio equal to or greater than 1.0
 The risk of developing the Eisenmenger syndrome is determined by the
size of the initial left-to-right shunt and type of the defect.

74.  Approximately 50% of all patients with large unrepaired
VSDs, approximately 10% of patients with large
unrepaired ASDs, and almost all patients with
unrepaired truncus arteriosus are at risk of developing
ES-lange,kidd(2nd natural history study)

77. Clinical Presentation :
 Dyspnea, cyanosis, fatigue, dizziness and syncope are
the common presenting symptoms.

79.  Eisenmenger syndrome is a multisystem disorder affecting almost all systems.
a. HEMATOLOGY—Hyperviscosity syndrome , ↑ thrombotic (viscosity, dilated
cardiac chambers, atrial fibrillation) as well as bleeding (thrombocytopenia, ↓
coagulation factors) risk.
b. CNS—Paradoxical embolism, hyperviscosity leads to ↑ stroke risk. Brain
abscess risk increased.
d. CORONARY CIRCULATION—Vasodilation leads to dilated, tortuous and
aneurysmal coronaries. Coronary flow reserve is decreased.
e. BILIRUBIN METABOLISM—Erythrocytosis - gall stone formation.
f. RENAL/RHEUMATOLOGIc- hyperuricemia, glomerular dysfunction can lead
to urate stones, renal dysfunction
g. SKELETAL—Hypertrophic osteoarthropathy, clubbing

81.  Cyanosis
 Most florid when the shunt was at ventricular level and least with a
patent ductus.
 PDA -60% of were acyanotic in the head and upper extremities. only
4% had gross cyanosis,differential cyanosis-50%
 Clubbing
 PDA -absent in 76% of the cases ,considerable in only 5%;
 VSD-Absent 3% and gross 36%.
 ASD-Intermediate
 SQUATTING is more frequent with ventricular septal defect (15%)
than with atrial septal defect(5%) or patent ductus (3%)

82. Physical features
 Pulse-small volume with atrial septal defect (88%) , ventricular septal
defect (37%) or patent ductus (50%).
 Bidirectional aorto-pulmonary shunts -water-hammer pulses
(12%).(p.wood)

83.  JVP - gaint a waves are uncommon except in some cases of ASD.
 RV impulse palpable in ASD(57%),rare with VSD/PDA
 An impulse over the pulmonary -66% of cases in each group.

84.  S2 -:
1. ASD –wide fixed
2. VSD –single (55%),wide varying(12%)
3. PDA –narrow/wide varying(50%),single(6%)
 Right atrial gallop -38% of cases with interatrial shunt, but in only 2 to
3% of the others.
 Pulmonary ejection click -in about two-thirds of all cases.
 Functional pulmonary ejection murmur, usually of moderate intensity
and relatively short duration, -80% of all cases, -loud in 25%

85. Second Congenital Heart Disease Natural History
Study (1993)
 Demontrated that patients with ES can survive for several decades
following diagnosis.
Survival rates in ES :
 30 years of age: 75%
 40 years of age: 70%
 55 years of age: 55%

86. WHY GOOD PROGNOSIS?
1. RV appears to adapt to the rise in pressure through hypertrophy and
preservation of a fetal-like phenotype.
1. Regression of the physiologic right ventricular hypertrophy does not
occur .
1. Eisenmenger patients were able to maintain their systemic CO at the
expense of cyanosis.

87. IPAH EISENMENGER
DURATION of
SYMPTOMS
SHORT
Development of HF RAPID
CENTRAL CYANOSIS LATE EARLY
HEMOPTYSIS RARE COMMON
SYNCOPE COMMON RARE
CLUBBING RARE PROMINENT
JVP - a wave prominent Less
Left parasternal heave prominent Less
Left 2nd ICS pulsation less more
S2 Single / narrow
P2 – not loud
1. ASD –wide fixed
2.VSD–single(55%),wide varying(12%)
3.PDA–narrow/wide varying(50%),
single(6%)
TR / PR murmur More common Less common

88. Catheterization - hemodynamic evaluation and
quantification of PAH in the Eisenmenger syndrome
is not advisable – reasons:
 Association of PAH with Pulmonary venous hypertension due to left
atrial hypertension or atrioventricular valve regurgitation.
 Pulmonary venous obstruction.
 Pulmonary parenchymal disease or restrictive lung disease.
 In situ pulmonary artery thrombosis.
 Altered anatomic relations and hemodynamics that may impede
routine catheter advancement and positioning.
 PVR is flow dependent so it may not necessarily fall in proportion to
the reduction in shunt and pulmonary blood flow.

89.  Lung biopsy is NOT routinely used in diagnosing Eisenmenger
syndrome. As information that is required can be obtained by
noninvasive methods and the procedural risks exceed the benefits.

90. TREATMENT
 Digoxin has been used in palliative therapy for right heart failure in ES,
although available evidence supporting its use is particularly weak.
 Diuretics – patients with volume overload.

92. Treat and repair strategy
 1.Despite established, long-standing
pulmonary vascular disease with
evidence of significant vascular
remodelling/obstruction, one-third
of Eisenmenger syndrome patients
maintain some degree of pulmonary
vasoreactivity to advanced therapy.
 2.Reverse remodelling may favour
surgery(Type B)

93.  Bosentan In addition to vasodilatory actions, also has anti-fibrotic,
anti-proliferative and antiinflammatory actions.
 Prostacyclin analogues inhibit platelet aggregation and smooth muscle
cell growth.
 The additional properties of these drugs have a role in preventing or
slowing vascular remodelling.

94. PROBLEM
 Pretreatment can cause an increase in shunt volume (by increasing the
compliance of the downstream chamber or vascular bed) and a
consequent increase in pulmonary blood flow.
 This may result in a paradoxical increase in pulmonary vascular
damage if left unguarded and operation is not done in time may
endanger life

96. Criteria for response to CCB s
 MODIFIED BARST CRITERIA which is defined as a 20% decrease in
mean pulmonary artery pressure (PAPm) with normal or sustained
cardiac output and no change or decrease in the ratio of pulmonary to
systemic vascular resistance (PVR/SVR) has been associated with a
sustained response to CCBs.
 SITBON CRITERIA (e.g., a decrease in PAPm by 10 mm Hg to a value
<40 mm Hg with sustained cardiac output) has not been studied
adequately in children with PAH.

97.  7% to 30% of children with IPAH and 6% of those with APAH are
responders to acute vasodilator testing.
 The development of pulmonary edema in response to pulmonary
vasodilators suggests diseases such as PCH, PVOD, or in infants,
nonketotic hyperglycinemia.
 A rising capillary wedge pressure secondary to increased cardiac output
may be the first sign of impending left ventricular failure.
 An increase in RA pressure in the face of rising cardiac output suggests
RV diastolic dysfunction.

98. PIT FALLS
 Reversibility seen in <10%.
 Technical difficulties leading to calculation errors and other medical
conditions need to be considered .
 Controversy in choosing protocol that predicts best response following
surgery .
 Advanced therapies for PAH have a combined vasodilative and
antiproliferative effect.
 Thus, there is also evidence to suggest that the pulmonary
hemodynamics and the clinical status may improve irrespective of the
response to acute vasodilator testing.

99. TREATMENT
 Pediatric PAH treatment goals may be divided into
those that are for patients at lower risk or higher risk
for death.

102. Atrial Septostomy
 Atrial septostomy may benefit patients with severe PAH with recurrent
syncope and intractable right heart failure.
 Right-to-left shunting through an interatrial defect allows to maintain
the cardiac output to the expense of increased hypoxemia, and
alleviates signs of right heart failure by decompression of the right
heart.
 Improvement of symptoms and increased survival have been reported,
but this remains controversial.
 Patients with severe PAH, right heart failure and markedly elevated
PVR may not tolerate atrial septostomy because of a massive
intracardiac right-to-left shunting and secondary severe hypoxemia.

103.  Potts Shunt
 Creation of a Potts shunt (anastomosis between the left pulmonary
artery and the descending aorta) may allow a decrease in right
ventricular afterload with subsequent improvement in right ventricular
function
 The Potts shunt allows a “systolic” pop-off whereas atrial septostomy
offers a “diastolic” pop-off.
 A potential advantage of the Potts shunt is maintenance of upper body
saturation with lower extremity desaturation.
 The high risk of the procedure should be reserved for the treatment of
children with right heart failure resistant to other forms of therapy.

104. Transplantation
 Referral to lung transplantation centers is recommended for patients
who are in World Health Organization (WHO) functional class III or
IV on optimized medical therapy or who have rapidly progressive
disease or patients who have confirmed pulmonary capillary
hemangiomatosis or PVOD.
 Limitations to transplantations are the shortage of donors and the high
incidence of bronchiolitis obliterans syndrome which limits the long-
term survival after lung transplantation.

105.  The median survival for those transplanted was 5.8 years.
 One-year survival rates of approximately 70% after HeartLung
transplantation, and 55% after lung transplantation.
 Five- and 10-year survival rates are 51% and 28%, respectively, after
HLT.