Ductus Arteriosus Dependent Congenital Heart Disease Amjad Kouatli MD. FAAP. FACC. Consultant Pediatric Cardiologist King Faisal Specialist Hospital and Research Center Jeddah

Anatomy of Ductus Arteriosus • Large channel found in mammalian fetuses. • Connects the main pulmonary artery to descending aorta. • Its media consists mainly of smooth muscles compared to elastic fibres in MPA, DAO.

Physiology of Ductus Arteriosus • Carries 60% of combined vent. output • Diverts blood from high resistance pulmonary circulation to low resistance descending aorta and placental circulation. • PGE1 and PGI2 formed intramurally and in placenta maintain ductal patency in fetal life

Post Natal Closure of PDA • Functional closure

In 12 hr., contraction of medial smooth muscles due to  PO2 &  PGE1.

• Anatomical closure In 3 wk., replacement of muscle fibres with fibrosis creating ligamentum arteriosus. • Silent without hemodynamic compromise to either pulmonary or systemic circulation

Before Birth

After Birth

If ductal closure causes significant decrease in systemic circulation, the condition is called ductus dependent systemic blood flow If ductal closure causes significant decrease in pulmonary circulation, the condition is called ductus dependent pulmonary blood flow

DUCTUS ARTERIOSUS DEPENDENT SYSTEMIC BLOOD FLOW Lesions characterized by the entire or part of the systemic blood flow depends solely on the patency of the ductus arteriosus. – Coarctation of Aorta (severe) – Interrupted Aortic Arch – Hypoplastic Left Heart

Critical Coarctation

Interrupted Aortic Arch

IAA between LCC, LSC

Hypoplastic Left Heart

Clinical Presentation • Normal birth weight and initial examination • Symptoms start suddenly when the duct closes.

• 40% are symptomatic first 2 days of life. • Tachypnea, dyspnea, grunting, flaring, ashen colour, and cyanosis. • Hyperactive precordium, tachycardia, hypotension, weak or absent femoral pulses, single S2, systolic heart murmur.

Investigations • Laboratory Metabolic acidosis, hypoglycemia hyperkalemia. • ECG: RAD, RVH • Chest X ray: mild cardiomegaly mild to severe increased pulmonary vascular markings.

Echocardiogram

Aortic Atresia Hypoplastic LV

Echocardiogram

Interrupted Aortic Arch Critical Coarctation

DUCTUS ARTERIOSUS DEPENDENT PULMONARY BLOOD FLOW • Hypoxic lesions characterized by the pulmonary blood flow depends solely on the patency of the ductus arteriosus. – Pulmonary atresia – Severe pulmonary stenosis – TOF with severe pulmonary stenosis

TOF Critical PS

Pulmonary Atresia

Clinical Presentation • Normal birth weight and initial examination • Symptoms start suddenly when the duct closes. • Progressive cyanosis, tachypnea. • Hyperactive precordium, tachycardia, single S2, TR systolic murmur, normal pulses.

Investigations • Laboratory hypoxemia not responding to O2 hypocarbia (hyperventilation).

• ECG: LAD, LVH .

• Chest X ray; mild to severe cardiomegaly, decrease in pulmonary vascular markings.

Echocardiogram

Critical Pulmonary Stenosis

Pulmonary Atresia Intact ventricular septum Hypoplastic RV

Treatment Prostaglandin E1 • IV via a large vein, 0.05- 0.1 ug/kg/min • Side effects: apnea 10%, hypotension, inhibition of platelets aggregation, fever, diarrhea, flushing, bradycardia, seizures, arrhythmia. • Therapeutic response is judged – Femoral pulses restoration, pH in DDSBF – Resolved cyanosis in DDPBF

Treatment cont.

• Correction of metabolic acidosis with sodium bicarbonate, acidosis decreases actin and myosin coupling.

• Correction of hypoglycemia and hypothermia. • Surgical or transcatheter intervention: Palliation: Complete correction:

HLHS

Norwood

Hybrid

PA-IVS

BT Shunt

PDA Stent

Treatment cont.

Cardiac Catheterization

For balloon valvuloplasty in critical PS

RV injection, AP view Critical PS, Severe TR RV hypertrophy

RV injection, lateral view PV annulus 4.4 mm Effective opening < 1 mm

0.014 wire crossed Pulmonary valve Balloon inflated Waist is visible Balloon inflated Waist disappeared

Pre Balloon dilatation Decreased pulmonary blood flow RA dilatation

After Balloon dilatation More blood to lungs Decreased RA size

Treatment cont.

Oxygenation, Ventilation • Oxygen and hyperventilation are excellent pulmonary vasodilator leading to decrease pulmonary vascular resistance. • Hypo oxygenate and hypo ventilate in ductus dependent systemic blood flow. • Oxygenate and ventilate in ductus dependent pulmonary blood flow.

Effect of oxygen on pulmonary and systemic circulation.

Oxygen decreases PVR 5

2.5 2

5 2.5 10

2.5

5 100%

80 %

4

10

4

92 % 5

8

100%

100%

5

2

60%

60%

PVR = SVR

PVR  SVR

2 60%

Summary • Ductus dependent congenital heart disease should be considered in every newborn – presenting with shock or cyanosis – physical examination shows hyperactive precordium, heart murmur, or weak pulses • Prognosis improves dramatically with early diagnosis, early infusion of Prostaglandin and early understanding of the disease physiology