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Patent Ductus Arteriosus Charlotte Maxeke Johannesburg Academic Hospital & UNIVERSITY OF THE WITWATERSRAND Dr. K. Vanderdonck Cardiothoracic Surgery Hannes.

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Presentation on theme: "Patent Ductus Arteriosus Charlotte Maxeke Johannesburg Academic Hospital & UNIVERSITY OF THE WITWATERSRAND Dr. K. Vanderdonck Cardiothoracic Surgery Hannes."— Presentation transcript:

1 Patent Ductus Arteriosus Charlotte Maxeke Johannesburg Academic Hospital & UNIVERSITY OF THE WITWATERSRAND Dr. K. Vanderdonck Cardiothoracic Surgery Hannes Meyer Registrar Symposium 3-5 June 2011

2 Classification of Congenital Cardiac Lesions Failure to thrive (FFT); congestive cardiac failure (CCF); pulmonary blood flow (PBF) Anomalies Charateristics Acyanotic 1.L  R Shunt = ↑ PBF Triad: FFT Chest infections CCF PDA ASD VSD A-V Canal 2. Obstructive Often asymptomatic Coarctation Aortic stenosis Pulmonary stenosis Cyanotic 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

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 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

5 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) Patent Ductus Arteriosus Definition

6 Ductus arteriosus & its postnatal closure described by Galen in 131 AD Physiologic importance of ductus arteriosus elucidated by Harvey in 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 Laborde performed first VATS closure PDA Patent Ductus Arteriosus Historical Background

7 Derived from distal aspect of the embryological left 6 th arch By 6 th week of gestation, ductus arteriosus carries between 55 and 60% of the combined ventricular output Patent Ductus Arteriosus Embryology

8 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 Embryology

9 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 pO 2, but low pO 2 maintains duct patency –pH + other factors play role RV & LV function in parallel + Share systemic and placental circulations Patent Ductus Arteriosus Foetal Physiology

10 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 pO 2 ) Patent Ductus Arteriosus Histology

11 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 Patent Ductus Arteriosus Postnatal Events

12 Postnatal closure occurs in 2 stages: 1.Functional or reversible closure: contraction of medial smooth muscle Occurs within 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 Patent Ductus Arteriosus Postnatal Ductal Closure

13 Contraction of smooth muscle cells due to: Increased pO 2 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) Patent Ductus Arteriosus Mechanisms of Ductal Closure

14 In preterm babies –Overall incidence 30% –Histologically normal ductus but immature Less sensitive to vasoconstricting effects of pO 2, More sensitive to vasodilating effects of PG –Less likely to respond to postnatal conditions of closure –Trial of Indocid –Early surgery if Indocid fails Patent Ductus Arteriosus Premature Babies

15 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 Patent Ductus Arteriosus Term Infants

16 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 Patent Ductus Arteriosus Anatomy

17 History Physical Examination CXR: Heart LungsECG Echocardiography (ECHO) + colour Doppler –Often diagnostic of the anatomy –Many operations done on ECHO data only Chest Xray (CXR); Electrocardiogram (ECG); Echocardiography (ECHO) Patent Ductus Arteriosus Diagnosis

18 Cardiac catheterization and angiography –To assess PAP + PVR and response to oxygen on pulmonary vasculature –To assess operability –PVR > 8 Wood units in 100% O 2 constitutes a contra-indication to surgery ( x 80 to convert to dynes-sec/cm -5 ) –Interventional cardiology MRI Patent Ductus Arteriosus Diagnosis

19 Patent Ductus Arteriosus Echocardiography

20 Patent Ductus Arteriosus Angiography

21 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 Patent Ductus Arteriosus Pathophysiology

22 : depends 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 Patent Ductus Arteriosus Physiological Classification

23 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 Patent Ductus Arteriosus Physiological Classification

24 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 Patent Ductus Arteriosus Physiological Classification

25 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 Patent Ductus Arteriosus Physiological Classification

26 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 Patent Ductus Arteriosus Physiological Classification

27 5-10% of all congenital cardiac defects M/F ratio = 1 : 2 1 in term live births Incidence higher in preterm babies = 20-30% Spontaneous closure –Common in premature babies –Rare in term infants Patent Ductus Arteriosus Incidence

28 Duct not closing postnatally = pathological From partial closure to wide open Factors: –Hypoxia –High altitude –Respiratory distress syndrome –Maternal rubella in 1 st trimestre –Low gestational age –Associated cardiac malformations Patent Ductus Arteriosus Incidence

29 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 Patent Ductus Arteriosus Complications

30 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 Patent Ductus Arteriosus Complications

31 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 Patent Ductus Arteriosus Complications

32 Medical therapy: –Depending on symptoms: Antifailure treatment InotropesVentilationAntibiotics –Pharmacological treatment: Indocid Surgery or intervention: presence of a duct is an indication for closure, except if pulmonary vascular obstructive disease Patent Ductus Arteriosus Treatment

33 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 hourly x 3 doses Associated with hepatic, renal, platelet dysfunction Inefficient in term babies Patent Ductus Arteriosus Treatment

34 General anesthetic + ventilation Invasive monitoring Risk of hypothermia Patient on right side Left postero-lateral thoracotomy in 4 th intercostal space Latissimus dorsi incision Patent Ductus Arteriosus Surgical Technique

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

37 Dissect under aorta on both sides PDA

38 Patent Ductus Arteriosus Surgical Technique Substraction TechniqueWhen large PDA + PHT

39 Patent Ductus Arteriosus Surgical Technique PDA ligation

40 Patent Ductus Arteriosus Surgical Technique PDA division

41 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 Patent Ductus Arteriosus Surgical Technique

42 In premature baby –Sick: communication with anaesthetist essential –Hand-bagging –Need to release the lung to allow ventilation –Proper dissection essential Patent Ductus Arteriosus Surgical Technique Clip Single ligation

43 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

44 Surgery in adult ductus: –More difficult – surgical risk higher than in children –Duct may be calcified –Consider median sternotomy and CPB Patent Ductus Arteriosus Surgical Technique

45 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 Patent Ductus Arteriosus Postoperative Complications

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47 Interventional cardiology VATS Patent Ductus Arteriosus Other Therapeutic Modalities

48 Patent Ductus Arteriosus Transcatheter Closure

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