CHANGES IN FETAL CIRCULATION AFTER BIRTH

CHANGES IN FETAL CIRCULATION AFTER BIRTHDEESHAN RAJ SIVASANKER 082013100017IMS BANGALOREChanges In Circulation After BirthCirculatory changes which occur after birth are divided into : i)Primary Changes ii)Secondary Changes

Primary Changes Tying of umbilical cord stops the placental circulation producing the following changes : i)blood flow through umbilical veins ceases causing contraction of Ductus Venosus within 1 -3 hours after birth ii)Systemic Vascular Resistance doubled . This increases the pressure in Left Atria , Left Ventricle , & Aorta iii)Marked decrease in volume of blood flowing up the Inferior Vena Cava together with expansion of previously collapsed lungs produces five fold decrease in Pulmonary Vascular Resistance . This leads to : a) Marked increase in Pulmonary Blood Flow b)Decrease in Right Atrium & Right Ventricle Pressure Secondary Changes Secondary changes includes : i)Closure of Foramen Ovale ii)Closure of Ductus Arteriosus iii)Closure of Ductus Venosus Closure of Foramen OvaleClosure of Foramen Ovale

Closure Of Ductus ArteriosusIncrease In Aortic Pressure & Decrease In Pulmonary Pressure Backward Flow of Blood From Aorta to Pulmonary ArteryGradual Constriction of Ductus ArteriosusPermanent Closure of Ductus Arteriosus

Closure of Ductus VenosusBlood Flow Through Umbilical Vein CeasesMuscular Wall of Ductus Venosus ContractsPortal Vein Pressure Increases from 0 mmHg to 10 mmHgForces Blood Flow Through Liver Sinuses