Congenital heart disease and other abnormalities Flashcards
What forms the cardiogenic mesoderm
Clusters of angiogenic cells
what arises from the cardiogenic mesoderm
From these arise right and left endocardial tubes.
what does lateral folding do
Lateral folding brings the tubes together and forms primitive heart tube.
when does lateral folding begin
o Occurs at day 21,
when is the foetal heart beat
beating by day 23.
describe the development of the heart
Tube lengthens and folds further into the bulboventricular loop.
By day 28 there is septation of the atria, ventricles and outflow tract.
Long periods of growth and maturation over 2 nd and third trimester.
what does failure of septation in the atria and ventricle cause
- can cause CHD
Can be early (AVSD from endocardial cushion) OR
Late (simple ASD or VSD).
Describe the parts of the primitive heart tube and what they develop into
- truncus arteriosus - this develops into the proximal aorta and pulmonary artery
- bulbs cordis - this forms the ventricular outflow tracts and right ventricle
- primitive ventricle - left ventricle
- primitive ratio - left and right atria
- sinus venous - smooth part of the right atrium and coronary sinus
what is dextrocardia
- this occurs when the heart is on the wrong side fo the chest
- happens when cardia looping happens in the wrong direction
describe how the atria septum is created (wall between the two atria)
- The septum starts to grow down from the top of the atria this is called the septum primum
- As it is growing down towards the endocardial cushion the space between them is called the ostium primum
- Before the ostium primum disappears completely a second hole forms this is called the ostium secundum
- Once osteium secundum develops osteium primum then closes and ostium secundum develops
- Once septum primum reaches endocardial cushions septum secundum starts to form and this goes down to the endocardial cushion
- Septum secundum leaves a hole in it and this is the foramen ovale
- Septum primum helps form this valve as well
what leaves a hole to form the foramen ovale
- Septum secundum leaves a hole in it and this is the foramen ovale
when does the atria septum develop
- Day 28/end of 4th week, two swellings of mesenchymal tissue appear from walls of the atria- endocardial cushsions
- The endocardial cushsions grow and fuse together to divide canal into R and L
describe how ventricular septum develops
- Has a muscular part that grows from the base of the heart to the endocardial cushions
- And a membranous component that grows down from the endocardial cushions towards the muscular part
- End of 4th week a muscular IVS develops from floor of primordial ventricle
- Grows towards membranous IVS which develops from endocardial cushions
what is the most common type of cardiac defect
VSDs
What are the parts of fetal circulation that are different to adult circulation
o Foramen ovale
o Ductus arteriosus*
o Ductus venosus
What is the role of the parts of fetal circulation that are different to adult circulation
• Foramen ovale - shunts blood from RA to LA (bypassing pulmonary circulation)
• Ductus arteriosus - shunts blood from pulmonary trunk to ascending aorta (bypassing lungs)
- Ductus venosus - shunts blood from umbilical vein to IVC (bypassing liver)
what causes the blood not to go through pulmonary circulation in a foetus
- in a foetus there is high pulmonary pressure and lower systemic pressure
- there there is a high resistance int he lungs so it is difficult for blood to flow through
What is transitional circulation
this is when the infant is born and in its first few days it transitions from a foetal heart circulation to an adult heart circulation
What happens transitional circulation and why
Closure of ductus arteriosus (increased oxygen levels).
Closure of foramen ovale.
o Due to drop in pressure in pulmonary circulation/right side of heart.
Shunting is reversed and valve closes.
Closure of ductus venosus.
o Due to decrease in blood flow in inferior vena cava.
What causes the ducts arteriosus to stay open in the uterus
o In utero ductus is kept open under influence of PG E1.
What is persist pulmonary hypertension of the Newborn
This is when after birth in the newborn pulmonary resistance does not decrease therefore you can end up with persistent pulmonary hypertension of the newborn
when does persistent pulmonary hypertension of the newborn occur
Occurs if problems with lungs (pneumonia, aspirate meconium).
describe the mechanism of action behind persistent pulmonary hypertension of the newborn
o There is increase pressure in PA keeping foramen ovale open.
Shunting of deoxygenated blood into systemic circulation (baby will be cyanotic).
will the baby have cyanosis in persistent pulmonary hypertension of the newborn
baby will be cyanotic
what are the two groups of congenital heart disease
Cyanotic CHD
• Patient is blue (cyanosed)
Acyanotic CHD
• Patient is pink (not cyanosed)