Patent Ductus Ateriosis PDA Muhammad Syed MD. Heart. High vascular resistance of the fluid-filled fetal lung . Low vascular resistance of the placenta . Right-to-left shunts. Two right-to-left shunts occur in the fetus Foramen ovale — Blood shunted from the right to left atrium
of the fluid-filled fetal lung
Low vascular resistance
of the placenta
If the flap forms incompletely or does not completely seal close, then deoxygenated blood can pass from the right atrium to the left atrium. A patient with an open or patent foramenovale will have a heart murmur. Unfortunately, this heart murmur maybe undetectable and the patient will exhibit no other obvious symptoms.
If the ductus arteriosus remains open after birth and fails to close it is referred to as a patent ductus arteriosus.
large vessel with a diameter similar to that of the descending aorta
Mainly on Low arterial oxygen content
Also is influenced by dilators,
Facilitates ductal constriction
Hydrocortisone treatment decreases the
sensitivity of the ductus to the dilating action
Constrictors (Increased O2)
PGE2, a vasodilator
Anatomic closure usually is complete within one to three months.
In term infants, functional closure after birth
24 hours 50 %
48 hours in 90 %
72 hours in virtually all
In preterm infants, ductal closure can be
delayed and the ductus can reopen following
Occurs especially when accompanying respiratory disease is present.
Severe respiratory distress syndrome; in ill infants less than 30 W
gestation, PDA persists on the fourth day in approximately 65 %
Two other factors may be important:
PGE2 and NO, in contrast to term infants whose ductus
loses responsiveness shortly after birth
Shunting of blood flow through a PDA in prematures is essentially all left-to-right
Preterm animals and infants with a PDA
increase their cardiac output. However,
postductal blood flow is reduced, which may
lead to organ dysfunction.
(deterioration of respiratory status )
left atrial or ventricular enlargement),
Recommend closure of a small audible PDA
even in the absence of a significant L-to-R
Never have hemodynamic consequences
Risk Of endocarditis
death compared to infants who never had a significant PDA
Interventions for PDA closure include:
Inhibitors of prostaglandin synthesis, such
as indomethacin and ibuprofen, are used as
the initial interventions for PDA closure in
Indomethacin has proven to be ineffective in
term infants and older patients with a PDA.