66 Questions
Which organ is not fully functional in a fetus?
Liver
What is the main function of the placenta in a fetus?
To provide oxygen and nutrients
Which blood vessel carries oxygenated blood from the placenta to the liver in a fetus?
Umbilical vein
What is the pathway of most of the blood entering the right atrium (RA) in a fetus?
Through the tricuspid valve into the right ventricle (RV)
What type of blood mainly enters the right atrium (RA) from the superior vena cava (SVC) in a fetus?
Deoxygenated blood
Where does most of the well-oxygenated blood from the placenta enter in a fetus after reaching the right atrium?
Left atrium (LA)
What is the purpose of the ductus venosus in a fetus?
To carry oxygenated blood from the inferior vena cava to the right atrium
Which blood vessel carries deoxygenated blood from the head region of the fetus to the right atrium (RA)?
Superior vena cava (SVC)
What does the foramen ovale connect in a fetus?
Right atrium (RA) and left atrium (LA)
Which vessel does blood mainly flow through after leaving the pulmonary artery?
Descending aorta
What happens to systemic vascular resistance (SVR) at birth?
It increases
What happens to pulmonary vascular resistance at birth?
It decreases
What is the result of the expansion of the lungs at birth?
Increased blood flow
What happens to the resistance to blood flow in the lungs when they expand?
It decreases
What happens to the right atrial pressure at birth?
It decreases
What happens to the left atrial pressure at birth?
It increases
What happens if the closure of the valve between the left and right atria does not occur?
Patent foramen ovale
What causes the closure of the ductus arteriosus?
Increased oxygenation of blood
Which structure prevents blood from flowing backwards from the left atrium into the right atrium in a fetus?
Small valve around Foramen Ovale
What is the term used to describe the permanent closure of the foramen ovale?
Anatomical Occlusion
What causes the closure of the ductus arteriosus?
Increased oxygenation of blood
What is the term used to describe the failure of the ductus arteriosus to close?
Patent Ductus Arteriosus
What is the main function of the placenta in a fetus?
Exchange of nutrients and waste products between the mother and fetus
What happens to the systemic vascular resistance (SVR) at birth?
Decreases
What happens to the resistance to blood flow in the lungs when they expand?
Decreases
What happens to the right atrial pressure at birth?
Decreases
What happens to the left atrial pressure at birth?
Increases
Which type of congenital malformation is the most common at birth?
Ventricular Septal Defect
What happens to ventricular septal defects (VSDs) over time, during childhood in most cases?
They close spontaneously during childhood
What is the consequence of a large ventricular septal defect (VSD)?
All of the above
What is the consequence of a persistent ostia/defect in atrial septal defects (ASDs)?
Left-to-right shunt
What is the main consequence of a left-to-right shunt in atrial septal defects (ASDs)?
Pulmonary hypertension
When do most cases of atrial septal defects (ASDs) become significant?
In adulthood
What is the main purpose of surgical correction for atrial septal defects (ASDs)?
Prevent irreversible pulmonary hypertension
Which of the following is true about congenital heart disease?
It accounts for 20-30% of all birth defects.
What is the main function of the ductus venosus in a fetus?
To allow most of the portal blood to bypass the liver.
What happens to the left atrial pressure at birth?
It increases.
Where does most of the well-oxygenated blood from the placenta enter in a fetus after reaching the right atrium?
Left atrium
What type of blood mainly enters the right atrium (RA) from the superior vena cava (SVC) in a fetus?
Deoxygenated blood
Which vessel carries most of the portal blood in a fetus?
Ductus venosus
When does most congenital heart disease arise?
During the third to eighth week of gestation
What causes bluish skin (cyanosis) in a patient with a right-to-left shunt?
Venous blood bypassing the pulmonary circulation
What initially happens in a left-to-right shunt in congenital heart disease?
Increased pulmonary blood flow
What is the consequence of increased pulmonary blood flow in congenital heart disease?
Right ventricular hypertrophy
What causes late onset cyanosis in congenital heart disease?
Left-to-right shunt reversing
What is the most common type of congenital malformation?
Left to right shuts
What happens to ventricular septal defects (VSDs) over time, during childhood in most cases?
They close spontaneously
Which structure is responsible for shunting blood from the pulmonary artery to the aorta in fetal life?
Ductus arteriosus
What happens to the ductus arteriosus after birth?
It constricts and closes
What happens if the ductus arteriosus remains patent after birth?
High pressure in aorta forces oxygenated blood into the pulmonary artery
What is the consequence of a patent ductus arteriosus after birth?
Volume and pressure overload in pulmonary vessels
Which condition is characterized by a right-to-left shunt that recirculates venous blood back into the systemic circulation?
Tetralogy of Fallot
What is the most common cause of a right-to-left shunt in congenital heart disease?
Tetralogy of Fallot
What happens in tetralogy of Fallot if the obstruction is mild?
Left-to-right shunt
What is the term used to describe the discordant connection of the ventricles to their vascular outflow?
Transposition of great arteries
What happens if there is complete transposition of the great arteries?
Incompatible with postnatal life
What is the purpose of a shunt in the context of transposition of great arteries?
To recreate a pathway for oxygenated blood to reach the systemic circulation
What is the prognosis of a patient with a shunt-related congenital heart disease?
Depends on the degree of tissue hypoxia and the ability of the right ventricle to handle the load
What is the narrowing or constriction of the aorta?
Coarctation of the aorta
What are the two forms of coarctation of the aorta?
With a PDA and without a PDA
What are the consequences of coarctation of the aorta without a PDA?
Hypertension in the upper body and weak pulse in the lower body
What is the recommended treatment for coarctation of the aorta?
Surgical correction to expand or remove the coarctation
What is the consequence of a large ventricular septal defect (VSD)?
LV hypertrophy and delivery of blood to the lower body
What is the frequency rank of coarctation of the aorta among common anomalies?
Highest
What are the symptoms of a patient with transposition of great arteries?
Poor weight gain and cyanosis
What determines the severity of coarctation of the aorta?
The severity of the narrowing and the patency of the ductus arteriosus
Study Notes
Fetal Circulation
- The liver is not fully functional in a fetus.
- The placenta is responsible for oxygenation and nutrient supply to the fetus.
- The umbilical vein carries oxygenated blood from the placenta to the liver in a fetus.
Fetal Blood Flow
- Most of the blood entering the right atrium (RA) comes from the inferior vena cava (IVC).
- The ductus venosus carries oxygenated blood from the placenta to the liver.
- The foramen ovale connects the right and left atria.
- The ductus arteriosus connects the pulmonary artery to the aorta.
Transition from Fetal to Neonatal Circulation
- At birth, systemic vascular resistance (SVR) increases.
- At birth, pulmonary vascular resistance decreases.
- Expansion of the lungs at birth leads to increased oxygenation and decreased pulmonary resistance.
- Right atrial pressure decreases at birth.
- Left atrial pressure increases at birth.
Congenital Heart Disease
- The most common type of congenital malformation is ventricular septal defects (VSDs).
- VSDs often close spontaneously over time during childhood.
- Large VSDs can lead to pulmonary hypertension and right heart failure.
- Atrial septal defects (ASDs) can cause left-to-right shunts, leading to increased pulmonary blood flow.
- ASDs can become significant if the defect persists over time.
- The main purpose of surgical correction for ASDs is to prevent complications.
Ductus Arteriosus
- The ductus arteriosus shunts blood from the pulmonary artery to the aorta in fetal life.
- After birth, the ductus arteriosus normally closes.
- If the ductus arteriosus remains patent after birth, it can lead to complications.
Other Congenital Heart Defects
- Tetralogy of Fallot is characterized by a right-to-left shunt that recirculates venous blood back into the systemic circulation.
- Transposition of the great arteries is a condition where the ventricles are connected to the wrong great arteries.
- Coarctation of the aorta is the narrowing or constriction of the aorta.
- Coarctation of the aorta can lead to hypertension and heart failure if left untreated.
Test your knowledge on fetal circulation and the differences between fetal and post-natal infants. Learn about the functional inactivity of fetal lungs, the dependence on the placenta for oxygen and nutrients, and the unique role of the liver. Discover the changes in fetal circulation at birth and how oxygenated blood is transported.
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