Saturday, November 13, 2010

Patent ductus atriosus

Patent Ductus Arteriosus (PDA)
    Persistence of a normal fetal channel connecting the aorta and pulmonary artery. This normally closes 12-24 hours after birth by a rise in perivascular PO2. It may be re-opened however in response to a strong stimulus such as acidosis, hypoxemia, or prostaglandin.

1 - open or patent ductus arteriosus
The shunt or abnormal flow is from aorta to
pulmonary artery as indicated by the shaded red arrow

Acyanotic defect...usually left to right shunt as blood is shunted from areas of high to low resistance. This causes pulmonary overcirculation and frequently CHF results.

When ductus fails to close normally, blood will shunt from the left to the right into the pulmonary artery and lungs resulting in pulmonary overcirculation leading to CHF.

A large PDA will result in a low diastolic pressure and may result in poor coronary perfusion.

Presentation depends on the magnitude of the left to right shunt.

Pre-term infants may present in sever low cardiac output states.

Machinery like continuous murmur can be heard at the left upper sternal border.

Hx of poor feeding, irritability, tachycardia, and tachypnea.

Pulse pressure is wide.

Peripheral pulses may be bounding.

CXR shows enlarged cardiac silhouette. Pulmonary vascular markings may be accentuated in moderate to large shunts.

IV, O2, Monitor.

3cc/kg/hr D10W  for infants under 1 year of age, D5W if over 1 year.

Medical therapy is control CHF, consider Lasix. 

Closure of the PDA with indomethican if kidney function and platelet levels are assured.

Surgical Ligation.

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