Fetal Circulation and Heart Function

Introduction

• Presenter: Sarah from RegisteredNurseArian.com
• Topic: Fetal Circulation
• Resource: Free quiz available after the video

Overview of Normal Heart Blood Flow

• Objective: Understanding blood flow in a heart outside the uterus.
• Key Points:
  • Blood flows from the right side to the lungs (for oxygenation) and then to the left side (to distribute oxygenated blood).
  • Right Side:
    • Receives deoxygenated blood.
    • Pumps to the lungs via pulmonary arteries.
  • Left Side:
    • Receives oxygenated blood from the lungs.
    • Distributes through the body via the aorta.
• Main Structures Involved:
  • Inferior and Superior Vena Cava
  • Right Atrium and Ventricle
  • Pulmonary Artery and Vein
  • Left Atrium and Ventricle
  • Aorta

Fetal Circulation

• Differences from a Mature Heart:
  • Lungs are fluid-filled and non-functional.
  • Presence of shunts to bypass the lungs.
• Shunts:
  • Ductus Venosus: Located near the liver.
  • Foramen Ovale: Between right and left atrium.
  • Ductus Arteriosus: Connects pulmonary artery to aorta.

Role of the Placenta

• Function: Provides oxygen and nutrients to the fetus.
• Mechanism:
  • Embeds in the uterus connecting with mother’s circulation.
  • Transfers oxygen and nutrients to the baby and removes waste.
• Umbilical Cord:
  • Components:
    • 1 Umbilical Vein: Carries oxygenated blood.
    • 2 Umbilical Arteries: Carry deoxygenated blood.

Detailed Fetal Blood Flow

• Start: Oxygenated blood from the umbilical vein.
• Liver: Blood splits; some go through the hepatic portal vein.
• Ductus Venosus: Shunts blood to the inferior vena cava.
• Right Atrium:
  • Oxygenated blood flows to the left atrium via Foramen Ovale.
  • Deoxygenated blood flows to the right ventricle.
• Right Ventricle: Blood pumped through pulmonary artery, mostly shunted to aorta via Ductus Arteriosus.
• Aorta: Blood circulates through descending aorta and internal iliac artery to umbilical arteries.

Transition After Birth

• Umbilical Cord Cut: Stops blood flow through the umbilical vein.
• Pressure Changes:
  • Lungs clear fluid, reducing resistance and pressure in the right side of the heart.
• Closure of Shunts:
  • Ductus Venosus: Ceases function.
  • Foramen Ovale: Closes due to pressure changes.
  • Ductus Arteriosus: Closes due to reduced prostaglandins and increased oxygen levels.

Additional Information

• Patent Foramen Ovale (PFO): A condition where the Foramen Ovale does not close properly.
• Prostaglandins: Chemical messengers affecting vessel closure.

Conclusion

• Recommendation: Take the quiz to test your understanding of fetal circulation.