Cardiac Abnormalities Flashcards
What is ventricular septal defect?
When there is a hole in the septum causing oxygenated blood to be pumped back through the lungs
What is coarctation of the aorta?
When the aorta is narrowed therefore increasing workload
What is Tetralogy of Fallot?
Four defects:
1) Narrowed pulmonary trunk and valve
2) Hypertrophy of right ventricle
3) Ventricular septal defect
4) Aorta opens from both ventricles
How does foetal circulation work?
- Oxygen is supplied by the placenta
via the umbilical arteries - The lungs are fluid filled and there is a great resistance to blood flow
- Oxygenated blood needs to enter the left side of the heart for systemic circulation
- The right side of the heart has a higher pressure than the left to allow this
How does neonate circulation work?
In the neonate:
- The various foetal
openings and shunts
need to be closed
- The left side of the heart has a higher pressure than the right
- Failure to close or an error in development may result in a cardiac abnormality
How does the heart develop?
- Heart develops from a ‘single’ muscular tube at day 22
- The heart needs to develop into four chambers and be able to function as both a foetal and neonatal heart
- Many abnormalities arise during development or during the transition from foetal to neonatal circulation
How does the atria develop?
As a foetus, oxygenated blood flows from the right side with higher pressure to the left through the foramen ovale. In the neonate, the atrium separates into two completely different spaces when the septum closes. This is because the pressure is now higher on the left side.
What are the steps of the development of the atria?
1) The septum primum starts to grow so as to separate the single atrium into two. Blood flows through the ostium primum right to left
2) The septum primum joins to the endocardial cushion and perforations, the ostium secundum, are made in septum primum to allow blood circulation.
3) The septum secundum forms with a foramen ovale to allow foetal circulation to continue
4) At birth the septum primum covers the foramen ovale
How do the ventricle develop?
- The single ventricle is divided into two by the growth of a septum
- If the septum fails to grow and join with the endocardial cushion or part of the septum is reabsorbed then a hole will be present
- This hole is a ventricular septal defect (VSD)
What is a cyanotic abnormality?
When deoxygenated blood enters the systemic circulation
What is a acyanotic abnormality?
When oxygenation of the systemic circulation is relatively normal (some oxygenated blood may re-enter the pulmonary circulation)
What are examples of cyanotic abnormalities?
- Tetralogy of Fallot
- Transposition of the Great Vessels
What are examples of acyanotic abnormalities?
- Ventricular septal defects (VSDs)
- Atrial septal defects (ASDs)
- Aortic stenosis
- Coarctation of the Aorta
What are ventricular septal defects (VDSs)?
- When the superior part of the interventricular
septum fails to form - Occurs in 1 in 500 births
- Acyanotic
What are atrial septal defects (ASDs)?
- When there is a hole in the septum which should separate the two atria
- Caused by the septum being to short or the foramen ovale being to large or both
- Acyanotic