Patent Ductus Arteriosus

What 2 factors sustain the *Patency (opening)* of the *ductus arteriosus during *fetal life*?

*PGE (postaglandins E)* and *low oxygen tension (lungs collapsed in fetal life)*. As soon as they breathe the *O2 tension increases and this promotes closure of the ductus arteriosus*.

A *patent ductus arteriosus* occurs when what fails to close? which is a connection between what 2 structures? fails to close after birth.

A *patent ductus arteriosus (PDA)* occurs when the *ductus arteriosus* (a *connection between the Aorta and Pulmonary Trunk*) *fails to close* after birth.

What is used to keep the *ductus arteriosus* open (patent) in certain heart defects?

PGE (E)

Postnatally, a *PDA* causes what kind of shunt? from what to what? Are babies with a *LDA* cyanotic after birth?

Postnatally, a *PDA causes a left-to-right* shunt (from aorta down to the pulmonary trunk) and is *non-cyanotic*. The newborn presents with a *machine-like murmur*

Why are babies with a *PDA* *non-cyanotic*?

because a PDA has a *left to right shunt, aka L (aorta) to R pulmonary trunk* into the *pulmonary arteries*.

*PGE inhibitors* such as: A. Indomethacin), B. Acetylcholine, C. Histamine, D. and catecholamines promote __________ *closure or opening* of the *ductus arteriosus* in a premature birth.

closure

Normally, the *ductus arteriosus* closes within a *few hours after birth* through *smooth muscle contraction* to form?

the *ligamentum arteriosum*= the closed *ductus arteriosus*.

What heart condition would you want to keep the *ductus arteriosus* open?

transposition of the great vessels. This condition occurs when the AP septum fails to develop in a *spiral fashion*. So deoxygenated blood from the RV pumps into the systemic blood through the *aorta* but in order to *oxygenate* blood you have to get it into the lungs. So keeping the *patent ductus arteriosus* open will allow the *deoxygeanted blood* from the RV that enters the *aorta* to fall back into the *pulmonary trunk* to enter the lung and be oxygenated. Once Oxygenated, the blood from the LV can spill through the *ventricular septal defect* into the *RV* to mix and then be transported into the systemic circuit.