FETUS CIRCULATION

Noverika WindasariMercubaktijaya - 2011

Sirkulasi Fetus berbeda dari sirkulasi posnatal :

• Paru

• Ginjal

• GIT

O2 & nutrien dari darah maternal

Saat lahir otomatis terjadi modifikasi ke arah normal

Belum berfungsi

Placenta

Is the “fetal lung”However cellular layers covering the villi are thicker and less permeable than the alveolar membranes in the lungs and exchange is much less efficient

Is also the route by which all nutritive materials enter the fetus and wastes are discharged to the maternal blood

SIRKULASI FETUS

Kebutuhan oksigen Fetus dari placenta

Vena Umbilikalis IVC

vena porta hepar

SVC / IVC RA

RA For. ovale LA LV Aorta asenden:

* 9 % arteri koronaria

* 62 % pembuluh carotis / subclavia

tubuh bagian atas / otak

* 29 % aorta desenden keseluruh tubuh

RV :

* Arteri Pulmonalis

- 80 % duct. Arteriosus aorta desenden tubuh

- 12 % ke paru-paru resistensi pembuluh darah paru meningkat

Perubahan sirkulasi fetus segera setelah lahir

Segera setelah lahir fetus akan menyesuaikan

dengan lingkungan luar

Plasenta paru-paru

Ductus venosus / foramen ovale / ductus

arteriosus tertutup

Umbilikal kord di clamped / kontriksi natural

Changes in Fetal Circulation

& Respiration at Birth At birth, placental circulation is cut off and

peripheral resistance suddenly rises

Pressure in aorta rises until > than in pulmonary artery

Because of placental circulation has been cut off, the infant becomes increasingly asphyxial

Finally, infant gasps several times and the lungs expand

Markedly negative intrapleural pressure (-30 to -50 mmHg) during the gasps contributes to the expansion of the lungs

Changes in Fetal Circulation

……………….& Respiration at Birth

The sucking action of the first breath plus constriction umbilical veins squeezes 100 ml of blood from placenta (the “placental transfusion”)

Once the lungs are expanded, the pulmonary vascular resistance falls to < 20% of utero value and pulmonary blood flow increases markedly

Blood returning from the lungs raises the pressure in the left atrium, closing foramen ovale by pushing the valve that guards it against the interatrial septum

Changes in Fetal Circulation

……………….& Respiration at Birth

Ductus arteriosus constricts within a few hours

after birth, producing functional closure, and

permanent anatomic closure follows in the next

24-48 hours due to extensive intimal thickening

Mechanism producing the initial constriction is

not completely understood, but the increase in

arterial O2 tension plays an important role

Changes in Fetal Circulation

……………….& Respiration at Birth

Relatively high concentrations of vasodilators

(especially prostaglandin) are present in the

ductus arteriosus

Synthesis of the prostaglandin is inhibited by

inhibition of cyclooxygenase at birth

In many premature infants the ductus fails to

close spontaneously, but closure can be

produced by infusion of drugs that inhibit

cyclooxygenase

Perubahan setelah lahir :

A.umbilicalis medial umblical ligament

V.Umbilicalis Lig.Teres (pd hepar)

Duct. venosus VC lig.venosum

Foramen ovale tertutup segera sesudah lahir

penekanan inter atrial septum

Duct arteriosus tertutup Lig.arteriosum

Beberapa kelainan kongenital

1. Tipe sianotik :

- Tetralogy Fallot

- Eisenmenger Syndrome

2. Tipe Non Sianotik :

- ASD

- PDA

- Congnital Aorta Stenosis

- Co Aortasio Aorta