7.1 Congenital Heart Defects (CHD) and Fetal Blood Flow Flashcards
Congenital Heart Disease
- Structural defect in heart or great vessels or persistence of a feta structure after birth.
- Cause is unknown but there are risk factors
RISKS
- Maternal viral illness such as rubella
- Maternal diabetic disorders such as diabetes
- Fetus is exposed to certain medications
- Genetics (Chromosomal Abnormalities such as Turners Syndrome or Downs Syndrome)
- Complications of pregnancy such as age or antepartum bleeding
Acquired Cardiac Disorders
- Abnormalities that occur after birth and can be seen after a normal birth.
Fetal Blood Flow
- Fetus receives oxygen from placenta
- O2 travels from placenta to fetus through the umbilical cord
Foramen Ovale - Allows blood to flow through right atrium and go directly to the left atrium bypassing the lungs
Ductus Arteriosus - Small vessel that connects the pulmonary artery to the aorta which gets pumped out to circulation
Blood eventually returns to the placenta to reoxygenate and go back.
Fetal lungs are filled with fluid and not preforming gas exchange. This is why blood is shunted away from the lungs.
Fetal Circulation
- Independent of maternal circulation (blood does not mix)
- Oxygenation occurs in the placenta not the lungs
- Switch over from fetal circulation to normal circulation happens in the first few hours of birth but the complete process takes 10-21 days.
(Umbilical)
- Arteries carry deoxygenated blood
- Veins carry oxygenated blood
Foramen Ovale
- Carries blood directly from the left atrium to the right atrium bypassing the lungs
- Closes due to pressure of left atrium growing greater than right atrium
Ductus Arteriosus
- Carries blood directly from the pulmonary artery to the aorta
- Closes due to increased oxygen in blood.
Normal Blood Flow of Heart
- Blood always flows from an area of high pressure to an area of low pressure and always takes the path of the least resistance
- Pressure on the right side of the heart is lower than the left side of the heart because pulmonary circulation is less resistant than systemic resistance.
Left to Right Shunt
- Defect where blood flows from left side of the heart to right side through an opening
Right to Left Shunt
- Blood travels through a defect from the right side to left side of the heart.
Physical Exam of Cardiac System
- Not enough to just listen to heart
- Skin color (tells how well the heart is pounding and how much oxygen the heart is actually pumping out to the body. Do you notice pallor or cyanosis. Are they pale? or mottling. Capillary Refill)
- Heart sounds (murmurs, rate, rhythm)
- Pulses (peripheral indication of how well the heart is pumping based on strength)
- Blood Pressure (how much volume is being pumped by the heart)
- Nutrition (patients with poor cardiac may have failure to thrive or poor eating habits due to lack of energy)
- Respiratory system (tachypnea, breath sounds, adventitious breath sounds, dyspnea, cyanosis)
Hemodynamic Change from Fetus to Infant
- Before birth pulmonary vascular resistance created by collapsed fetal lung causes greater pressure in the right side of the heart and pulmonary arteries.
- Placenta circulation and ductus arteriosus cause low vascular resistance in the remainder of the fetal circulation
- The first birth of an infant causes pulmonary vasodilation which causes pulmonary pressure to fall as systemic pressure increases.
- Forman Ovale closes due to increased pressure in the right side of the heart and left side pressure exceeds right side.
- Ductus arteriosus closes due to increased oxygen concentration in the blood
Secondary to increased pressure in right side of the heart it is also bigger than the left side during fetal life
VSD
- Infants with Ventricular Septal Defect can still live a long life
Cardiac Disease
- Affects physical growth, children with them tend to be smaller and lower body weight.
Femoral Artery
- Ideal site to assess young children’s central pulses
Children Pulses
- Always assess for a full minute
