L9 Embryology: Development of the Heart Flashcards
What is dextrocardia?
Dextrocardia when the inverse is isolated to the heart. It is as a result of incorrect cardiac looping. It can lead to transposition of the vessels.
When does the ligamentum arteriosum close off? How does this occur?
6 months
This is though to occur by contractile cells in the the duct contracting to leave a solid piece of tissue. The contraction is thought to be initiated by a decrease in prostaglandins.
What is the effect of a patent ductus arteriosus? What is the treatment?
If this remains open, blood can shunt from the aorta to the pulmonary trunk. This increase in the amount of blood means there is pulmonary hypertension. This causes the right ventricle to work harder as it needs to squeeze against the greater pressure. There is less blood in the left ventricle and so the left ventricle must pump harder. This leads to ventricular hypertrophy. If this continues, this can lead to heart failure.
Treatment: Prostaglandin inhibitors
How common is probe patent foreman ovale? What is the effect?
1 in 4
It is associated with a higher risk of migraine and stroke.
What are caused of atrial septal defects?
- The septum secundum may not develop enough and so the septum secundum does not overlap the septum premium.
- There is excessive apoptosis is the septum secudum
How do the septum premium and septum secundum come together?
Usually the septum primum and septum secundum come together to form the atrial septum due to the increase pressure, causing them to stick together. On the left side we work at a higher pressure and so the foremen primum is stuck against the foreman secundum. These then remain stuck together. They can only reopen when we have a difference in pressure e.g. in pulmonary hypertension. In this case, the septum primum and secundum can flap against each other.
What is a cor triloculare biventriculare?
A common atrium. A rare genetic condition in which there us a compete absence of the atrial septum.
What happened as a result of premature closure of the foreman ovale?
This results in hypertrophy of the right side of the heart and underdevelopment of the left side. This is as blood is not shunted to the left and so decrease volume in the left. Death usually occurs shortly after birth.
What type of heart defect is most common?
Ventricular septal defect.
A defect in the muscular septum usually development will cover this. A defect in the membranous septum leads to a left to right shunt causing pulmonary hypertension and hypertrophy.
Give examples of conotruncal septal defects.
- Persistant truncu arteriosus - a common outflow tract. This means there is mixing of the blood. The conotruncal septum cause the membranous part of the ventricular septum and so we get a ventricular septal defect where the blood can mix. This mixing of the blood can lead to cyanosis.
- Transposition of the great vessels - The septum runs straight down instead of spiralling. This means the right ventricle is ejected in the aorta and the left ventricle ejects blood into the pulmonary artery. This is incompatible with life most of the time
- Fallot’s tetralogy - The conotruncal septum spiralling displaces anteriorly. This is an unequal division of the truncus arteriosus of the aorticopulmonary septum, the vessels leaving the heart are a different size.
What abnormalities are seen in Fallot’s Tetralogy?
Overriding aorta, Pulmonary stenosis and ventricular septal defect leading to right ventricular hypertrophy.
What is a coarctation of the aorta?
Narrowing of the aorta
How can we classify coarctations of the aorta?
Preductal (before the ductus arteriosus) and post-ductal (after the ductus arteriosus).
How can a coarctation of the aorta be treated?
If the ductus arteriosus remains patents, we can still get partially oxygenated blood to the body. This is sufficient early on. Once this closes off, this can lead to a rapid decline in the infant with hypoperfusion of the lower body. This happens relatively quickly. This can be treated by administering prostaglandins to keep the ducts arteriosus open.
What can post ductus arteriosus coarctation give rise to?
Collateral blood supply
