Patent Ductus Arteriosus

Seoul National University Hospital

Department of Thoracic & Cardiovascular Surgery

Patent Ductus Arteriosus

1. Definition An open communication usually between upper descending aorta and proximal portion of left pulmonary artery and is the result of persistent patency of fetal ductus arteriosus

2. History * Galen : 1st description(Born in AD131) * Gibson : Continuous murmur in 1900 * John Strieder : Attempted to close in 1937 * Robert E. Gross : Successful ligation in 1938 * Rashkind & Cuaso : Catheter closure in 1977

Pathophysiology of PDA

• Left-to-right shunt from the thoracic aorta to the pulmonary artery leads to augmented pulmonary blood flow, pulmonary hypertension, and congestive heart failure.

• Demonstrating blood from across the ductus with associated left ventricular hypertrophy and left atrial enlargement and comprises 12~15% of congenital heart defects

Anatomy of Ductus Arteriosus 1. Position

* Unilateral

* Bilateral

* Absence ( 35-40% in TOF )

2. Histology of PDA

* Thick intima with unfragmented elastic lamina

* Media contains mucoid material with spiral muscular

intricate helicoid arrangement and elastic material

3. PDA as a coexisting anomaly

* Orientation of ductus to aortic arch varies

Morphology of Ductus Arteriosus

1. At birth * Resembles a muscular artery * Intima : intact wavy internal elastic lamina, split up into several layers and interrupted underneath intimal cushion * Media : mainly circular smooth muscle cells with minimal elastic fibers ( mucoid lake ) 2. Anatomic closure * Necrosis of cellular component of the media and diffuse fibrous proliferation of intima 3. Aneurysms of ductus arteriosus * Spontaneous infantile form * Childhood or adult form

PDA Gross Finding

PDA

PDA PDA

Postnatal Closure of Ductus Arteriosus

1. First Stage ( Functional closure ) * Within 10~15 hours after birth ( contraction of smooth muscle & approximation of intimal cushion ) 2. Second Stage (Anatomic closure ) * Completed by 2~3weeks ( fibrous proliferation of intima, necrosis of media, hemorrhage in the wall and sealing of the lumen ) * Ductus arteriosus is closed by 8 weeks in 88% 3. Physiology * Vasoactive substances ( acetylcholine, bradykinin, endogenous catecholamine and others ) by variations in PH, but chiefly by 02 tension and prostaglandins ( PGE1, PGE2, prostacyclin, PGI2 )

Natural History of PDA 1. Incidence * Isolated PDA : 1/2000 birth, 5-10% of CHD * Sex ratio ; male : female = 1 : 2 2. Spontaneous closure * 0.6% of patients per year. ( 20% by age of 60 ) * Uncommon over 3~5 months of age ( full term baby ) 3. Death * Untreated large PDA is high in infancy ( 30%) * 42% of patients with PDA will die by age of 45 4. Mode of Death * CHF in infancy * CHF by 2nd or 3rd decade in large PDA ( PVR ) * CHF 3rd or 4th decade in moderate PDA * Rare SBE

Clinical Features of PDA

1. Large PDA * Severe congestive heart failure within a month * Tachypnea, sweating, irritability, poor feeding,

2. Moderate PDA * Large shunt from the 2nd or 3rd months of age * Compensatory LVH with improvement & stabilization

3. Small PDA * Symptoms are absent in infancy and childhood * Continuous murmur 4. Silent PDA * Controversial in surgical treatment

Operation of PDA

1. Indication 1) Large PDA is indicated beyond the 1st month of life, but symptoms of heart failure is present, surgery is indicated 2) In the absence of symptom, operation delayed until the age of about 6 months

2. Contraindication : severe pulmonary vascular disease

3. Technique of operation 1) Division :divided rather than ligation 2) Ligation : In neonate or some infant 3) Closure of PDA in older adults * Using CPB (calcified aortic end, short ductus, PH)

4. Percutaneous closure ( Rashkind, Amplatzer, Coil ) 5. Thoracoscopic closure

Anatomy of PDA

• PDA as visualized from a left anterior oblique view

PDA Exposure

Operative Exposure of PDA

• PDA through a left thoracotomy & the mediastinal pleura

is opened and reflected anteriorly and posteriorly

Median Approach of PDA

• Closure of PDA from a median sternotomy approach

PDA Ligation

PDA Division

Thoracoscopic Surgery (VATS)

• Indications Isolated PDA associated with or without other

minor cardiac lesions

• Contraindications Complex congenital defects requiring CPB Ductus diameter larger than 9 mm Calcification of ductus Pleural adhesion or right aortic arch

Thoracoscopic Surgery (VATS)

• Why VATS PDA ligation -- Potential thoracotomy morbidity Long-term post-thoracotomy pain Postoperative pulmonary complication Thoracic scoliosis

-- VATS PDA ligation Decrease chest wall trauma Minimize nerve injury & rupture of intercostal ligament Cosmetic effect Painless

PDA Ligation by VATs

• An endoscopic vascular clip is placed to interrupt the patent ductus arteriosus. The arrow denotes the recurrent laryngeal nerve

Operative Results of PDA

1) Mortality 2) Incremental risk factors for early death * old age * pulmonary vascular disease 3) Survival 4) Symptomatic and functional status 5) Physical development 6) Recurrence 7) False aneurysm 8) Vocal cord paralysis 9) Phrenic nerve paralysis 10) Chylothorax

Management of Pre-term PDA

• General management Fluid restriction Ventilatory support Correction of anemia Correction of metabolic acidosis Diuretics; lasix decrease ECF volume, but increase prostaglandin production

• Indomethacin• Other cyclooxygenase inhibitor Ibuprofen Mefenamic acid

• Surgical treatment

PDA in Pre-term Baby (1)

1. Incidence Increase with decreasing gestational age & birth weight, but hemodynamic significancy is less. 28 ~ 30wks : 77% Wt under 1000gr : 40% 31 ~ 33wks : 44% Wt under 1750gr : 10% 34 ~ 36wks : 21%

2. Operative indications Failure of indomethacin trial Respiratory distress Necrotizing enterocolitis Intracranial hemorrhage

PDA in Pre-term Baby (2)

3. Operative results

Early mortality : 10~30%

Respiratory distress

Intracranial hemorrhage

Diffuse coagulopathy

Late : BPD in 1/3 of survivor

Complications (CP, retrolental fibroplasia)

in 1/6 of survivor