Fetal Circulation

Hypotension

Abnormally low blood pressure

Hypoglycemia

Abnormally low blood sugar level

Ventricular Septal Defect - VSD

Acyanotic; Left to Right shunt and CHF; Left sided cardiomegaly; Hole between Ventricles; Appears 6-8 wks as PVR falls; Oxygenated blood flows from Left to Right Ventricle (path of less resistance); Ventricle cannot pump. Big heart.

Patent Ductus Arteriosus - PDA

Acyanotic; Typically occurs in premature infants; Normally closes 5-7 days after birth of term infants; May act as Right to Left or Left to Right shunt depending on SVR and PVR; Causes Po2 to drop Treatment: 1. Pharmocology "indomethacin" 2. Surgical "ligation"

Atrial Septal Defect - ASD

Acyanotic; Typically of little importance; Incomplete closure of Foramen Ovale; Oxygenated blood flows from Left to Right Atrium; Blood is mixing

Air in Lungs at Birth

Air in Lungs Increase: PO2 = Increases pH = Increases PCO2 = Decreases Results in: 1. Pulmonary vasodilation & increased PVR 2. Ductus arteriosus constriction / closure 3. Increased pulmonary blood flow

Placenta

In utero, life depends on placental structure provides: Gas exchange; Nutrients & waste removal; Defense against disease - immunity

Tactile & Thermal Stimuli

Initiates 1st breath; Initial breath requires transpulmonary pressure >40cm H2O; Subsequent breaths require progressively less pressure as lung volume increases - usually more with a c-section.

Arterial Pressure at Birth

LAP > RAP: Foramen Ovale closes Transition to extrauterine circulation complete (in utero - the Right Heart has Higher pressure than the Left Heart)

Aorta

Largest artery in the body; Distributes blood to the body. Blood flows into the Internal Iliac Arteries. Blood with the most oxygen will reach the Brain.

Venous & Capillary Blood Gases

pH: 7.32 - 7.43 PaO2: 38-42 mmHg PaCO2: 38-55 mmHg SaO2: 60-80% HCO3: 22-26 Capillary values are close to arterial blood. That is why they do cap sticks because it is close in range and less invasive.

Arterial Blood Gases

pH: 7.35 - 7.45 PaCO2: 35-45 mmHg = Normal PaO2: 50-70 term = at Birth/ 30 fetus PaO2: 45-65 preterm = 36 wks or less HCO3: 22-26 SaO2: 92-94

Fetal Fluid

1/3 of fluid is expelled by vaginal squeeze at birth. Pulmonary Lymphatics absorb remaining fluid.

Right Atrium

1st chamber of the Heart; The mixed blood then moves from the Inferior Vana Cava to the right atrium of the heart. High pressure.

Right Ventricle

2nd chamber of the heart. SOME blood - mixed - is dumped from Right Atrium. Squeezes blood into Pulmonary Artery into both lungs. High pressure.

Left Atrium

3rd chamber of the Heart.: Oxygenated Blood flows from the Right Atrium via the Foramen Ovale.

Left Ventricle

4th chamber of the heart. Blood gets dumped from Right Atrium and from the Pulmonary Veins; Then blood gets squeezed into the Aorta.

Placenta

A mass of tissue that is attached to the wall of the uterus and connected to the developing fetus by the umbilical cord; it supplies nutrients and eliminates waste products; Mom's blood and fetus' capillaries in that pool of blood. Very low resistance - makes blood divert TOWARDS it - high amounts of blood - for oxygenation. Placenta does the work that the baby's lungs will do after birth.

Cardiomegaly

Abnormal enlargement of the heart

Stenosis

Abnormal narrowing of a passage in the body

Hypoplastic Left Heart Syndrome

Birth defect that affects normal blood flow through the heart. As the baby develops during pregnancy, the Left side of the heart does not form correctly.

Congenital Heart Disease Acyanotic Heart Disease

Blood shunts Left to Right Causes Congestive Heart Failure Hard for Left side to pump

Congenital Heart Disease Cyanotic Heart Disease

Blood shunts from Right to Left Bypassing Lungs Misses the Lungs - Deoxygenated blood by bypassing Aveolar Capillary - Aciodic = Blue baby

BPD

Bronchopulmonary dysplasia = COPD for babies

Contributing Factors for PPHN

Cardiovascular Factors: Systemic Hypotension Congenital Heart Failure Shock

Inferior Vena Cava

Carries blood from the lower half of the body; Mixing of oxygenated & deoxygenated blood (mixed blood). Then dumps blood into the Right Atrium (simultaneously from Superior Vana Cava).

Coarctation

Congenital narrowing of a short section of the aorta

Dextroposition

Everything is shifted; The aorta is displaced to the right and blood from both ventricles enters it; the heart is located in the right side of the chest and the apex points medially or to the left.

PaO2

Fetal = 30 Normal After birth = 50-70 Normal Adult = 80-100 Corr - Normal = Room Air

Contributing Factors for PPHN

Fetal Factors: Intrauterine stress Hypoxia Decreased pH Placental vascular abnormalities

Abruptio Placenta

Premature separation of the placenta from the uterus. Typically present with bleeding, uterine contractions, and fetal distress.

Fetal

Relating to a fetus

Foramen Ovale

Right Atriole pressure is higher than Left Atrium. Most oxygenated Blood can move across. Opening between the right and left atrium - most of the blood flows through this hole directly into the left atrium from the right atrium, thus bypassing pulmonary circulation.

Placenta Previa

Placenta lies low in the uterus and partially or completely covers the cervix. The placenta may separate from the uterine wall as the cervix begins to dilate (open) during labor.

Congenital

Present at birth

Reflex Pulmonary Vasoconstriction

Reflex contraction of vascular smooth muscle in the pulmonary circulation in response to low regional partial pressure of oxygen (Po2).

VSD

Ventricular Septa Defect (between the ventricles

At Birth

Infant = Adult circulatory

Umbilical Vein

Delivers oxygenated blood from the placenta to the fetus; Delivers oxygenated blood to the Liver area.

Foramen Ovale

Closes at baby's first breath at birth

Persistent Pulmonary Hypertension - PPHN

Commonly seen in infants with an underlying respiratory disorder: Pneumonia Maconium aspiration syndrome (MAS) Respiratory distress syndrome (RDS) Caused by: Reflex pulmonary vasoconstriction; High PVR; Right to Left shunting may occur

Ductus Arteriosus

Connection / vessel between the Pulmonary Artery & the Aorta. Mixed Blood bypasses pulmonary circulation by connecting the pulmonary artery directly to the ascending aorta. Because the Pulmonary Artery has very high pressure because of the high resistance in the lungs. Thus, blood flows from high pressure to lower pressure from the pulmonary artery to the Aorta via this arch. Sends the bluer Blood to the organs in the lower half of the fetal body.

Ductus Venosus

Connects (through it) the umbilical vein to the inferior Vena Cava, bypassing the liver

Umbilical Cord

Connects the vasculature of the fetus to the placenta; A cord or funicle connecting the embryo or fetus with the placenta of the mother and transporting nourishment from the mother and wastes from the fetus.

Tretalogy of Fallot

Cyanotic Heart; Pulmonary stenosis, VSD, dextroposition aorta, RVH; Timing of surgical repair dependent on case; Chest radiograph shows "boot-shaped" Heart Right to Left ventricle Left ventricle enlarged Not oxygenated Patient is Blue

Transposition of the Great Vessels / Arteries

Cyanotic; Arteries; Manifests as moderate to severe cyanosis at birth (dusky); Emergency atrial septostomy relieves distress (repair hole in Atria); Perform arterial switch operation 2-3 wks of life; Chest radiograph shows "egg-shaped" Heart; Diaphragm = lightly flattened; Hole or defect in ventricular septum; Hole or defect in atrial septum. Patent (open) ductus arteriosis. Aorta = transposed; - Aorta emerges from right ventricle. Aorta going to the Lungs vs normally to the tissues; Pulmonary artery emerges from left ventricle. Pulmonary Trunk to the tissues vs normally to the Lungs; Oxygenated blood going BACK to the Lungs = baby = aciodic Air in stomach = breathing extra hard = lots of air

Hypocalcemia

Deficient calcium in the blood

Superior Vana Cava

Delivers deoxygenated blood to the right atrium of the heart. It is a large-diameter (24 mm), yet short, vein that receives venous return from the upper half of the body, above the diaphragm. Located in the anterior right superior mediastinum.

Ligamentum Arteriosum

Ductus Arteriosus becomes Ligamentum Arteriosum at birth

Ligamentum Venosum

Ductus Venosus becomes Ligamentum Venosum 3-7 days from full term birth.

Pulmonary Veins

Dumps small amount of blood into the Left Atrium - because of high Lung resistance - very hard blood flow. A lot of blood goes into the Pulmonary Artery Trunk and into the Aorta.

Fetal Lungs

Full of fluid. Not much oxygen. Hypoxy Pulmonary Vasoconstriction. Lungs have a lot of resistance - making blood divert away from them. Pressure in the Pulmonary Artery is very high. No gas excahange takes place in fetal lungs.

Umbilical Cord at Birth

Hard to cut; examine for: Umbilical Vein (1) Umbilical Arteries (2) - continuous with the internal Iliac arteries **All vessels must be there; clamp twice**

Bounding Peripheral Pulse

Heart palpitations - abnormal fluttering or pounding of the heart; PDA murmur;

Contributing Factors for PPHN

Hematologic Factors: Increased hematocrit Septicemia Maternal-fetal blood loss 1. Abrupto placenta 2. Placenta previa

Left Ventricular Outflow Obstructions

Left Heart pumping obstruction; Aortic stenosis; Coarctation of aorta; Hypoplastic Left Heart syndrome; Left hardened stiff wall - nothing to squeeze; Cardiac output decreased Treatment depends on severity: 1. Initially protaglandin E1 2. Severe cases: Mechanical ventilation is required; Surgical procedures; 1. Stenosis and coarctation: resection or graph 2. Hypoplastic left heart: Norwood Procedure; Transplantation

Hypoxia

Low oxygen saturation of the body, not enough oxygen in the blood

Umbilical Arteries

Major branch of the Internal Iliac Arteries. Brings blood back to the Placenta (very low resistance - makes deoxygenated blood divert TOWARDS it - high amount of blood) for oxygenation. Not muscular in fetal

Contributing Factors for PPHN

Maternal Factors: Diabetes Cesarean Section Hypoxia

Contributing Factors for PPHN

Other Factors: Central Nervous System disorders Hypoglycemia Hypocalcemia Neuromuscular disorders

Fetal Circulation

Oxygenated, nutrient-rich blood from placenta carried to fetus via umbilical vein → half enters Ductus venosus (allows blood to bypass the liver) →carried to inferior vena cava → RA → RV → Ductus arteriosus (conducts some blood from the pulmonary artery to the aorta [bypassing the lungs/fetal pulmonary circulation]) → aorta. Other half enters liver/portal vein → RA → Foramen ovale (allows blood to bypass pulmonary circulation by entering the left atria directly from the right atria since there is no gas exchange in fetal lung) → LA → LV → aorta.

PVR & SVR

PVR = Pulmonary Vascular Resistance SVR = Systemic Arterial Circulation PVR = Fetal Normal = High SVR = Fetal Normal = Low PVR = After Birth Normal = Low SVR = After Birth Normal = High

RVH

Right ventricular hypertrophy Right ventricle enlarged.