Transcript SURGICAL INDICATIONS IN CONGENITAL HEART DISEASE

Patent Ductus Arteriosus
Dr. K. Vanderdonck
Cardiothoracic Surgery
Charlotte Maxeke Johannesburg Academic Hospital
& UNIVERSITY OF THE WITWATERSRAND
Hannes Meyer Registrar Symposium 3-5 June 2011
Classification of Congenital
Cardiac Lesions
• Acyanotic
Charateristics
3. Decreased PBF 4. Increased PBF
• Triad:
Often asymptomatic Cyanosis
FFT
Child well,
Chest infections
asymptomatic
CCF
Anomalies
1. LR Shunt 2. Obstructive
= ↑ PBF
• Cyanotic
PDA
ASD
VSD
A-V Canal
Cyanosis
Triad:
•FTT
•Chest infections
•CCF
Coarctation
Tetralogy
Truncus
Aortic stenosis
Pulmonary atresia TAPVC
Pulmonary stenosis Tricusp atresia a,b Tricuspid atresia c
TGV + PS
TGV
Failure to thrive (FFT); congestive cardiac failure (CCF); pulmonary blood flow (PBF)
Pathophysiology of LR shunts
Clinical importance of pulmonary vascular
resistance:
– Neonatal pulmonary artery pressure (PAP)
greater than that of adults
– Reaches adult levels by 2-3 months of age
– If PAP remains elevated in presence of a
shunt, development of pulmonary vascular
obstructive disease (PVOD)
Patent Ductus Arteriosus
Definition
Also called ductus of Botalli
Normal vascular structure in foetal life
Extracardiac lesion
Directly connects pulmonary and systemic arterial
systems
Persistence of ductus after 3 months in postnatal
period abnormal
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Definition
4 distinct clinical forms:
– Isolated PDA in otherwise healthy child
– Isolated PDA in premature baby
– Associated with more significant cardiac
defects
– As a life sustaining structure in cyanotic or
left-sided obstructive lesions (ductaldependent)
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Historical Background
Ductus arteriosus & its postnatal closure
described by Galen in 131 AD
Physiologic importance of ductus arteriosus
elucidated by Harvey in 1628
1938 Robert Gross at Boston Children’s Hospital
= first successful ligation
1967 Portsmann used polyvinyl alcohol plug
placed with catheter to close PDA
Indomethacin introduced by Heymann in 1976
1991 Laborde performed first VATS closure PDA
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Embryology
Derived from distal
aspect of the
embryological left
6th arch
By 6th week of gestation,
ductus arteriosus carries
between 55 and 60% of
the combined ventricular
output
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Embryology
Diverts blood away from high resistance
pulmonary circulation to descending aorta and
low pressure umbilical placental circulation
where gas exchange occurs
Ductal flow directly from PA into descending
aorta  ductus equal in width to descending
aorta and appears as direct extension of PA into
descending aorta
Patent Ductus Arteriosus
Foetal Physiology
Maintenance of foetal ductal patency:
– High levels of circulating and locally produced
prostaglandins (PGE 2 & PGE 1)
– As foetus matures, ductal smooth muscle
becomes more sensitive to vasoconstricting
effect of pO2, but low pO2 maintains duct
patency
– pH + other factors play role
RV & LV function in parallel + Share systemic
and placental circulations
Patent Ductus Arteriosus
Histology
The wall of the ductus differs from the
surrounding vascular structures:
– Media deficient in elastic fibres
– Composed primarily of poorly organized
smooth muscle cells in a spiral configuration
– Intima thick with increased number of mucoidfilled structures
– Smooth muscle sensitive to environmental
factors (vasodilating effect of prostaglandins
and vasoconstricting effect of pO2)
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Postnatal Events
At birth, rapid circulatory changes
– RV & LV function in series
– Lung ventilation  PVR drops and pulmonary blood
flow increases
– Due to increased pulmonary venous return,
LA pressure rises and PFO closes
– PDA closes:
Initially functional and reversible
Later anatomical and irreversible = ligamentum
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Postnatal Ductal Closure
Postnatal closure occurs in 2 stages:
1. Functional or reversible closure: contraction
of medial smooth muscle
Occurs within 10-15 hours after birth in full
term neonates
2. Anatomic or irreversible closure: Connective
tissue formation with fibrosis  produces
ligamentum arteriosus
Completed by 2-3 weeks
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Mechanisms of Ductal Closure
Contraction of smooth muscle cells due to:
Increased pO2 following lung ventilation
Decreased PG levels:
–Removal placenta = source of circulating PG
–Blood flow to lungs removed PG from
circulation
Contraction of smooth muscle greatest at pulmonary
end, extends to aortic end
Closure may be incomplete at aortic end (ductal
ampulla or ductal bump)
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Premature Babies
In preterm babies
– Overall incidence 30%
– Histologically normal ductus but immature
Less sensitive to vasoconstricting effects of
pO2,
More sensitive to vasodilating effects of PG
– Less likely to respond to postnatal conditions
of closure
– Trial of Indocid
– Early surgery if Indocid fails
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Term Infants
In term infants:
– Histology different from normal ductus:
Media contains elastic lamina similar to aortic
wall
Smooth muscle organized in fine helocoid spiral
fashion
Intima thick with a complete internal elastic
lamina
Variable mucoid deposits, lie mostly in media
– Is considered a congenital malformation
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Anatomy
PDA = extension of MPA
Curves under the aortic
arch
Joins descending aorta at
acute angle a few mm
beyond origin of LSCA
Recurrent laryngeal nerve
curves around PDA
Anatomic variations
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Diagnosis
History
Physical Examination
CXR:
Heart
Lungs
ECG
Echocardiography (ECHO) + colour Doppler
– Often diagnostic of the anatomy
– Many operations done on ECHO data only
Chest Xray (CXR); Electrocardiogram (ECG); Echocardiography (ECHO)
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Diagnosis
Cardiac catheterization and angiography
– To assess PAP + PVR and response to
oxygen on pulmonary vasculature
– To assess operability
– PVR > 8 Wood units in 100% O2 constitutes a
contra-indication to surgery ( x 80 to convert
to dynes-sec/cm-5 )
– Interventional cardiology
MRI
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Echocardiography
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Angiography
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Pathophysiology
Dependant on 2 factors:
– Size of shunt
– Difference between SVR and PVR
At birth, PVR elevated  little flow regardless of
size
As PVR drops, LtRt shunt increases
dependent of size of PDA
Persistent foetal circulation
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Physiological Classification
Physiological Classification: depends
– On the size of the PDA
– On the degree of pulmonary hypertension and
the pulmonary vascular resistance
– Important in terms of surgical indication
– Classified as small, moderate or large
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Physiological Classification
Small PDA
– Qp:Qs < 1.5:1
– Normal PA pressure / normal PVR
Asymptomatic in childhood
Life long risk of infective endocarditis
– SBE on PDA − PV − AoV − mycotic aneurysm
of descending aorta
Surgery on infected PDA risky
Interventional cardiolgy / transcatheter closure
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Physiological Classification
Moderate size PDA:
– Moderate pulmonary hypertension
– Do not develop Eisenmenger syndrome
Mild symptoms: some growth retardation, fatigue
on effort
May be asymtomatic
Presence of loud murmur with diastolic spillover
+ thrill
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Physiological Classification
Large PDA
– Direct large communication between MPA
and Aorta
– PA pressure equal to systemic
– Qp:Qs increased to a degree dependent on
PVR
Can develop Eisenmenger syndrome
CCF – FTT – Chest infections
Systolic murmur
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Physiological Classification
Eisenmenger syndrome:
– Severe pulmonary vascular obstructive
disease which is irreversible
– Presence of suprasystemic PA pressures and
PVR with shunt reversal (Rt  Lt shunt)
– Increasing cyanosis
– Death
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Incidence
5-10% of all congenital cardiac defects
M/F ratio = 1 : 2
1 in 1 600 term live births
Incidence higher in preterm babies = 20-30%
Spontaneous closure
– Common in premature babies
– Rare in term infants
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Incidence
Duct not closing postnatally = pathological
From partial closure to wide open
Factors:
– Hypoxia
– High altitude
– Respiratory distress syndrome
– Maternal rubella in 1st trimestre
– Low gestational age
– Associated cardiac malformations
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Complications
Death in infancy high due to CCF for large PDA
Death in early, middle adulthood
– CCF in moderate size PDA
– PVOD + Eisenmenger in large PDA
SBE = complication of small PDA
Respiratory tract infections
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Complications
Ductal aneurysms
– Dilatation of the PDA or remaining ductal
tissue
– Spontaneous or postoperative
– Spontaneous = true aneurysms
– Postoperative after PDA ligation
Often false aneurysm
Can be true aneurysm
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Complications
Ductal aneurysms
– Spontaneous infantile ductal aneurysm
Present at birth or shortly thereafter
Often regress spontaneously
– Second type develops in childhood or
adulthood
Due to patency at aortic end
Greater tendency for progressive dilatation
and rupture
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Treatment
Medical therapy:
– Depending on symptoms:
Antifailure treatment
Inotropes
Ventilation
Antibiotics
– Pharmacological treatment: Indocid
Surgery or intervention: presence of a duct is an
indication for closure, except if pulmonary
vascular obstructive disease
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Treatment
Premature babies:
– Presence of large PDA associated with organ
hypoperfusion + do not tolerate LV overload
well
– Trial of Indomethacin = inhibitor of
prostaglandin synthetase
0.1 – 0.2 mg / kg 12-24 hourly x 3 doses
Associated with hepatic, renal, platelet
dysfunction
Inefficient in term babies
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Surgical Technique
General anesthetic +
ventilation
Invasive monitoring
Risk of hypothermia
Patient on right side
Left postero-lateral
thoracotomy in 4th
intercostal space
Latissimus dorsi incision
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Surgical Technique
Mediastinal pleura
opened along
descending aorta, to
origin of LSCA
Superior intercostal vein
Care taken to avoid
vagus nerve
Recurrent laryngeal
nerve defines PDA, but
don’t go looking for it
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Surgical Technique
PDA dissected
with blunt
angled
instrument until
completely free
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Surgical Technique
Dissect under aorta on both sides PDA
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Surgical Technique
Substraction Technique
When large PDA + PHT
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Surgical Technique
PDA ligation
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Surgical Technique
PDA division
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Surgical Technique
Mediastinal pleura is closed: if bleeding, closure
will tamponade bleeding and allow exploration
One single pleural drain for 24 hours
In small infants: intercostal muscles
approximated with a continuous suture
In older children: 1 or 2 pericostal sutures placed
Patient usually extubated postop
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Surgical Technique
Clip
Single ligation
In premature baby
– Sick: communication
with anaesthetist
essential
– Hand-bagging
– Need to release the
lung to allow
ventilation
– Proper dissection
essential
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Surgical Technique
PDA with severe reversible PHT
PDA with single pulmonary artery
– Need cardiac cath and evaluation PVR
– Presence PFO
– Partial ligation PDA
– Restudy later + Interventional closure PDA
Patent Ductus Arteriosus
Surgical Technique
Surgery in adult ductus:
– More difficult – surgical risk higher than in
children
– Duct may be calcified
– Consider median sternotomy and CPB
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Postoperative Complications
Accidental ligation LPA or aorta in small babies
– importance of proper dissection
Recanalisation of ductus: rare even with ligation
if properly done
Left vocal cord paralysis – phrenic nerve
paralysis uncommon
Chylothorax: rare
Bleeding
Aneurysm of PDA
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Postoperative Complications
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Other Therapeutic Modalities
Interventional cardiology
VATS
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Transcatheter Closure
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Transcatheter Closure
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Transcatheter Closure