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Patent Ductus Arteriosus

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Presentation on theme: "Patent Ductus Arteriosus"— Presentation transcript:

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 Classification of Congenital Cardiac Lesions
Anomalies Charateristics Acyanotic 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 FTT Truncus TAPVC Tricuspid atresia c TGV 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 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 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)

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 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

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 muscle Occurs within hours after birth in full term neonates Anatomic or irreversible closure: Connective tissue formation with fibrosis  produces ligamentum arteriosus Completed 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 (ductal ampulla 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 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 1st trimestre 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 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 4th intercostal space Latissimus dorsi incision

35 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 don’t go looking for it

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 extubated postop

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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