Congenital Heart Disease Flashcards
Outline the embryological development of the heart
- There is a cluster of angiogenic cells that is present in the mesodermal cardiogenic plate
- The right and left endocardial tubes fuse to form a single cardiac tube
- Folding into the bulboventricular loop occurs
- Atrial, ventricular and outflow tract septation
- There is then postnatal closure of the foetal connections
When do the left and right endocardial tubes fuse?
Day 21
When does the heart start beating?
Day 23
When does atrial, ventricular and outflow tract separation occur?
Day 28
What is the function of the foramen ovale in foetal circulation?
Connects the atria, and allows right to left shunting
What is the function of the ductus arteriosus in the foetal circulation?
Connects the descending aorta with the pulmonary artery to allow shunting from the pulmonary artery to the aorta to bypass the high resistance lungs (which are currently non-functional)
What is the function of the ductus venosus in the foetal circulation?
To bypass the liver
What is persistent pulmonary hypertension of the newborn?
Where there continues to be a greater pulmonary pressure, and therefore blood continues to be shunted from the right to left side of the heart (through foramen ovale) which may cause cyanotic heart condition
What are cyanotic heart lesions?
Where blood from the right side of the heart goes to join the left (deoxygenated blood goes to the oxygenated region)
What are acyanotic heart lesions?
Where blood from the left side of the heart goes to join the right (oxygenated goes to the deoxygenated region)
Name three cyanotic heart disorders
Tetralogy of Fallot, persistent TRUNCUS arteriosus, transposition of the great vessels
Name four acyanotic heart disorders
Atrial septal defect, ventricular septal defect, patent DUCTUS arteriosus, coarctation of the aorta
Describe Tetralogy of Fallot
> Ventricular septal defect
Narrow right ventricular outflow (due to infundibular senses)
Right ventricular hypertrophy (due to high right ventricular pressure)
An over-riding aorta directly above the septal defect (so carries mixed blood)
Describe persistent truncus arteriosus
Only one artery (truncus) arising from the heart; usually due to a large VSD below the truncal valve
Describe transposition of the great vessels
The conotruncal septum fails to follow the spiral course, and instead runs straight down; this leads to the incorrect vessel-ventricle pairing
How is transposition of the great vessels treated?
Fossal ovalis is opened to allow greater mixing of the blood
How may you re-open the ductus arteriosus therapeutically?
Using prostaglandin E
How do atrial septal defects present?
Usually asymptomatic for first 30 years of life, but may occur on exertion
Describe patent ductus arteriosus
Persistent opening between the descending aorta and the pulmonary artery, leading to greater oxygenated blood travelling to the lungs
What are the potential complications of a patent ductus arteriosus?
Increases the risk of getting bacterial endocarditis
How is patent ductus arteriosus treated?
Adminstration of a prostaglandin inhibitor or surgical clipping
What is coarctation of the aorta?
Where there is constriction of the aorta; either above or below the ductus arteriosus.
Pre-ductal allows the ductus arteriosus to persist and allow blood flow. Post-ductal requires collateral circulation to form for proper perfusion of the body and legs
What’s the difference between pre-ductal and post-ductal coarctation of the aorta?
Pre-ductal allows the ductus arteriosus to persist and allow blood flow. Post-ductal requires collateral circulation to form for proper perfusion of the body and legs
How may coarctation of the aorta present?
Hypertension and decreed lower extremity pulses
Why may diuretics and ACE inhibitors be used to treat acyanotic heart lesions?
To prevent too much blood going across the foramen oval by reducing the blood pressure exerted on the structure
Define atresia
Absence or abnormal narrowing of an opening or passage in the body
What can neural tube defects lead to?
Spina bifida occulta, meningocoele, myelomeningocoele (spina bifida), encephalocoele and anencephaly
What is spina bifida occulta?
Closed, asymptomatic neural tube defect in which some of the vertebrae are not completely closed
What is meningocele?
Where there is protrusion of the meninges (filled with CSF) due to a defect in the skull of spine due to neural tube defect
What is myelomeningocoele?
Where there is an open spinal cord with a meningeal cyst
What is anencephaly?
Where there is an open brain and lack of skull vault due to neural tube defect
What is encephalocele?
Where there is herniation of the meninges and brain due to a neural tube defect
What is gastroschisis?
Where there is a small defect in the full thickness of the abdominal wall just lateral to the umbilicus (bowel is exposed)
What is exomphalos/omphalocoele?
A wide-based defect where a membrane covers herniated viscera
What is the cause of cleft lip and palate?
Failure of the maxillary and frontonasal processes fusing
