Circulation Part I SPRING 2026 POSTED

NUR 4 Spring Circulation Lecture Part I

Circulatory Review

• Congenital Heart Defects (CHD): General overview of heart defects present at birth.
    - Increased pulmonary blood flow defects:
      - Atrial Septal Defect (ASD)
      - Ventricular Septal Defect (VSD)
      - Patent Ductus Arteriosus (PDA)

Plan for Lecture

• Objectives:
    - Review normal blood flow through the heart.
    - Categorize defects to assist in recalling symptoms and treatment.
    - Understand fetal circulation and fetal blood flow to grasp the implications of defects.

Introduction & Definition

• Congenital Heart Defect (CHD):
    - A global term encompassing various defects in the newborn.
    - Defined as one or more structural heart problems present at birth and is the most common form of birth defects.
    - Statistics:
      - 8 out of every 1000 infants born in the U.S. annually have a heart defect.
      - Historically, only 10% of children with CHD survived into adulthood; advancements in treatment have led to approximately 90% survival.
• Ligation:
    - Surgical procedure to close off a vessel or duct using a ligature or clip.

Normal Anatomy & Physiology - Review

• Blood Flow:
    - Oxygen-rich blood enters the heart from the lungs and is distributed to the body.
    - Oxygen-poor blood returns to the heart from the body and is sent to the lungs for oxygenation.

Blood Flow: Right Side of the Heart - Review

• Process:
    - Un-oxygenated blood returns via the Superior Vena Cava (SVC) and Inferior Vena Cava (IVC).
    - Blood enters the Right Atrium (RA).
    - Transferred through the Tricuspid Valve into the Right Ventricle (RV).
    - Shunted through the Pulmonic Valve into the Pulmonary Artery (PA) toward the lungs.
• Pressure: This side operates under low pressure.

Blood Flow: Left Side of the Heart – Review

• Process:
    - Oxygenated blood exits the lungs via Pulmonary Veins (PV).
    - Enters the Left Atrium (LA) and passes through the Bicuspid (Mitral) Valve into the Left Ventricle (LV).
    - Blood is pumped through the Aortic Valve into the Aorta for distribution to the body.
• Pressure: The left side functions under high pressure.

Transition to Fetal Circulation

• Understanding the differences in fetal circulation is crucial to comprehending congenital heart conditions.
• Normal fetal circulation includes adaptations that do not occur after birth.

Step 1: Fetal Blood Flow from Mom to Fetal Heart

• Oxygen & Nutrients Transfer:
    - From mother to fetus via the placenta and umbilical cord.
    - Blood flows through the Umbilical Vein to the fetus's liver, where it enters via the Ductus Venosus.
    - Most highly oxygenated blood travels through the IVC to the RA.

Step 2: Blood Flow in the Fetal Heart

• Blood Pathway:
    - Oxygenated blood from the RA passes to the LA via the Foramen Ovale.
    - From LA to LV, then to the Aorta, supplying crucial areas (brain, heart, lower body).
    - In the RV, instead of traveling to the lungs, blood is shunted to the Aorta through the Ductus Arteriosus.

Summary of Normal Prenatal Blood Flow

• Key Points:
    - Umbilical Vein: Transports oxygenated blood to fetus.
    - Umbilical Arteries: Carry deoxygenated blood from fetus to placenta.
    - Ductus Venosus: Bypasses the liver.
    - Foramen Ovale: Shunts blood from RA to LA.
    - Ductus Arteriosus: Connects PA to descending Aorta bypassing lungs.

Fetal Circulation - Overview

• Blood Paths:
    - From Umbilical Vein through Ductus Venosus to IVC.
    - High-pressure system in fetal circulation leads to shunting at Foramen Ovale and Ductus Arteriosus.

Fetal Adaptations

• Unique pathways:
    - Umbilical Vein: Carries oxygenated blood.