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Patent Ductus Arteriosus

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. Acyanotic. Cyanotic. L  R Shunt = ↑ PBF Triad: FFT Chest infections CCF PDA

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Patent Ductus Arteriosus

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  1. 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

  2. Acyanotic • Cyanotic • LR Shunt • = ↑ PBF • Triad: • FFT • Chest infections • CCF • PDA • ASD • VSD • A-V Canal 2. Obstructive Often asymptomatic Coarctation Aortic stenosis Pulmonary stenosis • 3. Decreased PBF • Cyanosis • Child well, • asymptomatic • Tetralogy • Pulmonary atresia • Tricusp atresia a,b • TGV + PS • 4. Increased PBF • Cyanosis • Triad: • FTT • Chest infections • CCF • Truncus • TAPVC • Tricuspid atresia c • TGV Charateristics Anomalies Classification of Congenital Cardiac Lesions Failure to thrive (FFT); congestive cardiac failure (CCF); pulmonary blood flow (PBF)

  3. 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)

  4. Patent DuctusArteriosusDefinition • 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

  5. Patent DuctusArteriosusDefinition • 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)

  6. 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 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

  7. 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

  8. 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

  9. Patent Ductus Arteriosus Foetal Physiology • Maintenance of foetalductal 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

  10. 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)

  11. 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

  12. 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

  13. 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 (ductalampulla or ductal bump)

  14. 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

  15. 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

  16. 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

  17. 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)

  18. Patent Ductus Arteriosus 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

  19. Patent Ductus Arteriosus Echocardiography

  20. Patent Ductus Arteriosus Angiography

  21. 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

  22. 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

  23. Patent Ductus Arteriosus 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

  24. 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

  25. Patent Ductus Arteriosus 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

  26. 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

  27. 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

  28. 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 1sttrimestre • Low gestational age • Associated cardiac malformations

  29. 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

  30. 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

  31. 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

  32. 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

  33. 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

  34. Patent Ductus Arteriosus Surgical Technique • General anesthetic + ventilation • Invasive monitoring • Risk of hypothermia • Patient on right side • Left postero-lateral thoracotomy in 4thintercostal space • Latissimusdorsi incision

  35. 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 Patent Ductus Arteriosus Surgical Technique

  36. Patent Ductus Arteriosus Surgical Technique • PDA dissected with blunt angled instrument until completely free

  37. Patent Ductus Arteriosus Surgical Technique Dissect under aorta on both sides PDA

  38. Patent Ductus Arteriosus Surgical Technique Substraction Technique When large PDA + PHT

  39. Patent Ductus Arteriosus Surgical Technique PDA ligation

  40. Patent Ductus Arteriosus Surgical Technique PDA division

  41. 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 extubatedpostop

  42. 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

  43. 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

  44. 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

  45. 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

  46. Patent Ductus Arteriosus Postoperative Complications

  47. Patent Ductus Arteriosus Other Therapeutic Modalities • Interventional cardiology • VATS

  48. Patent Ductus Arteriosus Transcatheter Closure

  49. Patent Ductus Arteriosus Transcatheter Closure

  50. Patent Ductus Arteriosus Transcatheter Closure

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