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ORIGINAL ARTICLE
Anatomical Variations of Pulmonary Artery and Associated
Cardiac Defects in Tetralogy of Fallot
Sadia Saeed, Syed Najam Hyder and Masood Sadiq
ABSTRACT
Objective: To determine pulmonary artery variations and other associated cardiac defects in patients with Tetralogy of
Fallot (TOF).
Study Design: Cross-sectional, descriptive study.
Place and Duration of Study: The Children’s Hospital and the Institute of Child Health, Lahore, from April 2006 to October
2007.
Methodology: All patients with TOF, who underwent cardiac catheterization during this period, were included. Standard
cine-angiograms were recorded and pulmonary artery sizing was done using z-scoring.
Results: A total of 216 patients with TOF were catheterized. Pulmonary Artery (PA) abnormalities were present in 84
(38.9%) patients. The commonest abnormality was isolated Left Pulmonary Artery (LPA) stenosis (n=27, 32.14%) followed
by isolated hypoplasia of Main Pulmonary Artery (MPA) (n=18, 21.43%) and supra-valvular stenosis in (n=11, 13.1%)
patients. LPA was absent in one patient, while 2 patients had both absent right and left PA with segmental branch
pulmonary arteries originating directly from MPA. Associated cardiac lesions included right aortic arch in 34 (15%),
additional muscular VSD vary in 13 (5.5%), Patent Ductus Arteriosus (PDA) in 11 (6%) and Major Aortopulmonary
Collateral Arteries (MAPCA) in 2 (1.9%) patients. Significant coronary artery abnormality was present in 10 (4.6%)
children.
Conclusion: Pulmonary artery abnormalities were present in 38.9% of patients with TOF. Isolated LPA origin stenosis and
MPA hypoplasia were the most common abnormalities. Significant associated cardiac lesions were present in one-third
of the patients and included PDA, additional muscular VSD, coronary artery abnormalities and MAPCA.
Key words:
Cardiac catheterization. Pulmonary artery variants. Tetralogy of Fallot.
INTRODUCTION
Tetralogy of Fallot (TOF) is the most common cyanotic
congenital heart disease; with an incidence of
approximately 0.5/1000 live births making 5-7% of
congenital heart lesions.1-3 TOF is a congenital cardiac
anomaly characterised by a large ventricular septal
defect, muscular obstrucion within the right ventricular
outflow tract, rightward deviation of the aorta with
biventricular connection of the valvar leaflets so that its
orifice overrides the ventricular septum, and the right
ventricular hypertrophy.4 In the current era, TOF is
almost universally amenable to surgical repair with good
long-term outcome. This, however, requires a thorough
pre-operative anatomic description of central and
branch pulmonary arteries and associated defects, like
additional muscular VSD, ductus arteriosus, Major
Aortopulmonary Collateral Arteries (MAPCA) for better
surgical planning and a better outcome.5,6 Echocardiography with Doppler interrogation gives an
Department of Paediatric Cardiology, The Children’s Hospital
and Institute of Child Health, Lahore.
Correspondence: Dr Sadia Saeed, 11-B-3, Gulberg III, Lahore.
E-mail: [email protected]
Received March 25, 2008; accepted January 15, 2009.
accurate diagnosis of intracardiac anatomy of these
patients. Cine-angiography, however, compliments the
echocardiographic study as it allows more accurate
evaluation of pulmonary vasculature, coronary arteries
and additional ventricular septal defects.7,8 This invasive
study is regarded as necessary to obtain an exact
description of cardiac lesions and pulmonary artery
variations prior to deciding on surgical management
strategies in patients with TOF.
There is a limited data on these variations and
associations in the local population where patients
usually present late and more severe forms have natural
attrition. This study was designed to determine various
anatomic variations in pulmonary vasculature and other
associated cardiac defects in patients with TOF.
METHODOLOGY
This cross-sectional descriptive study was conducted at
the Children’s Hospital and the Institute of Child Health,
Lahore, from April 2006 to October 2007. All patients
with echocardiographic diagnosis of TOF, undergoing
cardiac catheterization during the study period, were
selected for evaluation. Patients who had undergone a
shunt procedure or had Complete Atrioventricular Septal
Defect (CAVSD) with TOF were excluded. Approval of
Journal of the College of Physicians and Surgeons Pakistan 2009, Vol. 19 (4): 211-214
211
Sadia Saeed, Syed Najam Hyder and Masood Sadiq
the hospital’s Ethics Committee was obtained for the
study, and parents of patients gave informed consent.
A majority of patients underwent cardiac catheterization
under local anaesthesia and sedation. A cocktail of 1%
pethidine (0.1 mg/kg) with chlorpromazine and an
antiemetic was given half an hour before procedure to
all patients. Effective sedation and analgesia were
maintained during the procedure, using midazolam and
ketamine.9 Right and left cardiac catheterizations were
done. Pressures were recorded with fluid-filled
catheters, and oximetry was carried out in the standard
manner. Cine-angiograms were done in the recommended positions.9,10
Pulmonary artery sizing was done using z-scoring. A
value of <-3 was taken to describe hypoplasia.11
Data were analyzed using SPSS version 15. The
variables like age and gender were presented as simple
descriptive statistics; calculating mean and standard
deviation of numerical data (age) and frequency
percentage for qualitative data (gender). The outcome
variables were angiographic findings (various
associated lesions and anatomic variations) and their
percentages were calculated. Since, this was a
descriptive diagnostic study, no test of significance was
determined.
RESULTS
A total of 216 patients with TOF underwent cardiac
catheterization during the study period. There were 150
(69.4%) males and 66 (30.6%) females. The age of
presentation was 6 months to 15 years with a mean of 6
(+ 3.75) years. Majority (47.6%) were between 6 months
and 5 years of age, followed by 38% patients between
5-10 years and 14.4% between 10-18 years.
All patients had levocardia (heart lying in normal left
hemi thorax) except 2 patients with dextrocardia, one of
whom had situs inverses as well. Pulmonary artery
variations were detected in 84 (38.88%) patients.
Regarding anatomic variations of pulmonary artery and
its branches, LPA stenosis was detected as the most
common lesion present in 27 (32.14%) patients followed
by MPA hyperplasia in 18 ( 21.43%). The frequency of
various pulmonary artery abnormalities is given in
Table I. Of patients with LPA stenosis; 5 had associated
Patent ductus arteriosus (PDA) as well. Six cases of
PDA were found in those cases where there was no
pulmonary artery stenosis. The patients having absent
LPA and RPA and absent LPA also had PDA.
Associated cardiac lesions found in catheterized
patients of Tetralogy of Fallot are shown in Table II. All
patients had normal origin of head and neck vessels.
Additional muscular ventricular septal defect was midmuscular in 9 (4.2%) patients and apical in 3 (1.4%)
patients. Of the coronary artery abnormalities, 6 (2.8%)
212
patients had prominent conal branch of right coronary
artery crossing RVOT, while 4 (1.9%) patients had
common origin of coronary artery from left coronary
cusp. Bilateral SVC was found in 6 (2.8%) patients.
Table I: Pulmonary artery abnormalities found in catheterized
patients of tetralogy of Fallot (n=84).
Pulmonary artery abnormality
Isolated LPA stenosis
Isolated RPA stenosis
MPA and LPA origin stenosis
RPA and LPA stenosis
Supravalvular stenosis
Isolated MPA hypoplasia
Isolated LPA hypoplasia
Uniform pulmonary artery hypoplasia
Hypoplastic RPA
Hypoplastic MPA and LPA
Hypoplastic RPA and LPA
Absent LPA
Absent LPA and RPA (segmental branches
originating directly from MPA)
RPA originating from left of MPA
Total
Frequency (Percentage)
27 (32.1)
2 (2.4)
2 (2.4)
2 (2.4)
11 (13.1)
18 (21.4)
6 (7.14)
6 (7.1)
2 (2.4)
2 (2.4)
2 (2.4)
1 (1.2)
2 (2.4)
1 (1.2)
84 (100)
LPA=left pulmonary artery; RPA=right pulmonary artery; MPA=main pulmonary artery.
Table II: Associated cardiac lesions found in catheterized patients of
tetralogy of Fallot (n=216).
Associated cardiac anatomic defects
Right aortic arch
PDA
Additional VSD
Coronary artery abnormalities
Bilateral SVC
MAPCA
Frequency (Percentage)
34 (15.7)
13 (6)
11 (5.5)
10 (4.6)
6 (2.8)
4 (1.9)
PDA=patent ductus arteriosus; VSD=ventricular septal defect; SVC=superior vena cava;
MAPCA=major aortopulmonary collaterals arteries.
DISCUSSION
Tetralogy of Fallot is the commonest cyanotic congenital
heart defect after first year of life. Surgery is the
standard form of treatment and cine-angiogram has
been the Gold standard in pulmonary vasculature
assessment to delineate anatomy prior to surgery.2 The
overall incidence of pulmonary artery abnormalities in
our population was found to be 38.9%, which is
comparable to the data from most centres of the world.12
The age of presentation in this study is, however,
relatively older with majority between 1 and 5 years of
age. Fellows and colleagues showed that a high
percentage (30%) of their TOF patients presented in first
year of life.12 This disparity is understandable as the
local primary and secondary healthcare structure is not
efficient enough to pick-up all children born with a
cyanotic CHD.
Isolated LPA stenosis was detected in 32.1% of this
study cases. This is significantly higher as compared to
the reported incidence of 3% and 10% from Asia and
Europe respectively.13,14 Stenosis of RPA (2.4%),
however, is comparable with data from Iran, where it
was found to be 2.2%.13 In this data, combined MPA
and LPA origin stenosis was also 2.4% again consistent
Journal of the College of Physicians and Surgeons Pakistan 2009, Vol. 19 (4): 211-214
Anatomical variations of pulmonary artery and associated cardiac defects in tetralogy of Fallot
with same Iranian population, where it was found to be
in 0.7%.13 Data from India showed that presence of PDA
was an important factor in development of discrete
pulmonary artery stenosis; where they found that
discrete stenosis was significantly present in patients
with PDA 67/84 than without PDA 5/96.15 A similar
association of PDA with pulmonary artery stenosis was
found in only 5 out of 27 patients of LPA stenosis had
associated PDA in this series at the time of
catheterization. This, however, does not exclude
possible complete closure of PDA leading to LPA
stenosis diagnosed on angiography subsequently.
Pulmonary artery stenosis with ductal insertion site was
diagnosed in 5 (1.3%) patients of TOF in a cohort of 373
patients in an American study.16 Hypoplasia of MPA was
detected in 21.43% of the presently reported TOF
patients, consistent with western data reported to be
9-22.2% of patients with TOF.2,17 In a local study
conducted at National Institute of Cardiovascular
Diseases, Karachi, 5 out of 31 patients (16%) with TOF
had markedly hypoplastic pulmonary vasculature.8
Three out of 5 patients having PDA and LPA origin
stenosis in this series also had MPA hypoplasia. Moon
Grady et al. showed a very high prevalence (59%) of
ductal insertion site-associated stenosis with high
prevalence of associated pulmonary artery hypoplasia.16
Supravalvular stenosis was present in 13% of the cases
as compared to 33.3% detected in an Indian research.17
Their percentage was high as they included patients of
TOF from 5 to 50 years of age.
Right aortic arch is not of functional importance but its
presence alerts the cardiologist for further investigations
in tetralogy of Fallot patients. In this data, right aortic
arch was found in 15% of patients as compared to the
reported incidence of 21-25% from the western
world.2,14,18
Patent ductus arteriosus was found in 6% of the patients
whereas reported cases of PDA in TOF from a Brazilian
study were 20%.2 This relatively low incidence may be
related to the delayed presentation leading to
spontaneous closure in some of these patients. Four of
our patients had Major Aortopulmonary Collaterals
Arteries (MAPCA), while a significant higher incidence is
reported in the literature. This data of PDA and MAPCA
is somewhat akin to the one described by Habibollah
et al. where PDA was found in 10% and MAPCA in 1.1%
of their tetralogy cases.13
coronary artery abnormality, which is consistent with the
previous studies.19,20 Depending as whether you include
minor abnormalities as well, incidence as high as 20%
has been reported.21 In this series, conal branch
crossing right ventricle outflow tract was found in 2.8%
of TOF patients as opposed to the documented
incidence of upto 15%.2 Single origin of coronary
arteries was found in 1.9% cases as compared to
4-4.8% in other worker’s results.2,13 Rest of the coronary
artery abnormalities like left anterior descending from
right coronary artery, left circumflex from right coronary
artery and conal branch from left anterior descending
artery were not detected in this group of patients.
Bilateral Superior Vena Cava (SVC) were found in 2.8%
of patients. This finding is important for the cannulation
prior to cardiopulmonary bypass and has been reported
to be as high as 11%.21
CONCLUSION
The frequency of pulmonary artery abnormalities in the
studied population of patients with TOF was high
(38.9%). Commonest pulmonary artery abnormality was
isolated LPA stenosis (32.1%) followed by MPA
hypoplasia in 21.43% and supravalvular pulmonary
stenosis in 13.09%. Important associated cardiac
lesions included PDA (6%), additional muscular VSD
(5.55%) and coronary artery abnormalities (4.6%).
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