6. Understanding Congenital Heart Disease Flashcards
Why does the foramen ovale exist prenatally?
To allow right to left shunting of oxygenated blood.
Why is there no mixing of deoxygenated blood with oxygenated blood being pumped around the systemic circulation with atrial septal defects?
Because the left atrium is higher pressure than the right atrium so flow is mostly left to right. This is therefore an acyanotic lesion.
What is an acyanotic lesion?
The shunting of blood goes from the left side to the right side through a lesion.
Where is the most common site of acyanotic lesions?
At the foramen ovale (ostium secondum atrial septal defect).
Where does an ostium primum atrial septal defect occur?
In the inferior portion of the septum, less common than ASD in foramen ovale.
What is a patent foramen ovale?
it is not a true ASD and can be clinically silent because the higher left atrial pressure causes functional closure of the flap valve.
What can happen with transient increase of right atrial pressure in a patient with patent foramen ovale?
Paradoxical embolism - it provides a route for a venous embolism to reach the systemic circulation.
What is a ventricular septal defect?
An abnormal opening in the interventricular septum - normally in the membranous portion of the septum.
What happens to blood flow with ventricular septal defects?
As the left ventricular pressure is much higher than the right, the blood will flow form left to right.
How do patent ductus arteriosus form?
The ductus arteriosus vessel doesn’t close as it should do after birth. Blood will flow from the aorta to the pulmonary artery after birth, this is down the pressure gradient.
What can chronic left to right shunting lead to?
Vascular remodelling of the pulmonary circulation and an increase in pulmonary resistance. If pulmonary resistance increases beyond that of the systemic circulation, the shunt will reverse direction on the right side of the heart - Eisenmenger syndrome.
What is coarctation of the aorta?
The narrowing of the aortic lumen in the region of the ligamentum arteriosum. This increases the afterload on the left ventricle so can cause left ventricular hypertrophy. Blood flow to regions other than head and upper limbs will be reduced.
How can coarctation of the aorta be picked up in adult life?
Femoral pulse will be weak and delayed, with upper body hypertension.
What is tetralogy of fallot?
A group of 4 lesions occurring together as a result of a single developmental defect which places the outflow portion of the interventricular septum too far in the anterior and cephalaudal directions.
What are the four anomalies of tetralogy of fallot?
Ventricular septum defect, overriding aorta, a variable degree of pulmonary stenosis and right ventricular hypertrophy.
