PERSISTANT DUCTUS ARTERIOSUS

Posted by e-Medical PPT Tuesday, July 3, 2012
Definition: Ductus arteriosus is a vessel that connects the pulmonary artery and aorta. Failure of closure and continued patency of fetal channel is termed PERSISENT DUCTUS ARTERIOSUS (PDA)
In the fetus, the ductus diverts blood flow from the pulmonary circulation (high resistance) to the descending aorta.
An Increase in PaO2 constricts the ductus. Other factors, such as the release of vasoactive substances, contribute to the closure
Balance between constricting/relaxing substances
In full term healthy newborns, functional closure occurs in 50% by 24 hrs of age, in 90% by 48 hrs.
The effects of oxygen and prostaglandins vary at different gestational ages.
Oxygen has less of a constricting effect with decreasing gestational age
Indomethacin constricts the immature ductus more than the term ductus

Factors assoc with increased incidence
Prematurity
Respiratory Distress Syndrome
Fluid overload
Asphyxia

Factors associated with decreased incidence
Antenatal steroid administration
IUGR
Prolonged rupture of membranes

Clinical Signs
The clinical features assoc with L to R shunt
depend on the magnitude of shunt and the ability to handle extra volume.
Shunt: magnitude and direction related to vessel diameter and pressure gradient between A and PA.
Murmur
Hyperactive precordium
Bounding peripheral pulses
Increase in pulse pressure
Hypotension
Respiratory deterioration

Complications of PDA
CHF
Pulmonary hypertension
Aneurysm of duct (rare)
Thromboembolism (rare)
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