Patent Ductus Arteriosus

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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
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Classification of Congenital Cardiac Lesions
Failure to thrive (FFT) congestive cardiac
failure (CCF) pulmonary blood flow (PBF)
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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)

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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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Patent Ductus Arteriosus 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 (ductal-dependent)

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Patent Ductus Arteriosus 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 Childrens 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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

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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

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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
  mucoid-filled structures
• Smooth muscle sensitive to environmental factors
  (vasodilating effect of prostaglandins and
  vasoconstricting effect of pO2)

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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus Postnatal Ductal Closure

• Postnatal closure occurs in 2 stages
• Functional or reversible closure contraction of
  medial smooth muscleOccurs within 10-15 hours
  after birth in full term neonates
• Anatomic or irreversible closure Connective
  tissue formation with fibrosis ? produces
  ligamentum arteriosusCompleted by 2-3 weeks

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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus Diagnosis

• Cardiac catheterization and angiography
• To assess PAP PVR and response to oxygen on
  pulmonary vasculature
• To assess operability
• PVR gt 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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Patent Ductus Arteriosus Echocardiography
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Patent Ductus Arteriosus Angiography
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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus Physiological
Classification

• Small PDA
• QpQs lt 1.51
• 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus Physiological
Classification

• Large PDA
• Direct large communication between MPA and Aorta
• PA pressure equal to systemic
• QpQs increased to a degree dependent on PVR
• Can develop Eisenmenger syndrome
• CCF FTT Chest infections
• Systolic murmur

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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus 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 dont
  go looking for it

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Patent Ductus Arteriosus Surgical Technique

• PDA dissected with blunt angled instrument until
  completely free

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Patent Ductus Arteriosus Surgical Technique
Dissect under aorta on both sides PDA
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Patent Ductus Arteriosus Surgical Technique
Substraction Technique
When large PDA PHT
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Patent Ductus Arteriosus Surgical Technique
PDA ligation
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Patent Ductus Arteriosus Surgical Technique
PDA division
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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus Surgical Technique

• In premature baby
• Sick communication with anaesthetist essential
• Hand-bagging
• Need to release the lung to allow ventilation
• Proper dissection essential

Clip Single ligation
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Patent Ductus Arteriosus 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

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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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Patent Ductus Arteriosus 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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Patent Ductus Arteriosus Postoperative
Complications
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Patent Ductus Arteriosus Other Therapeutic
Modalities

• Interventional cardiology
• VATS

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Patent Ductus Arteriosus Transcatheter Closure
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Patent Ductus Arteriosus Transcatheter Closure
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Patent Ductus Arteriosus Transcatheter Closure