CVS - Congenital Heart Defects Flashcards
How common are congenital heart defects?
Which are the most common?
- Common (6-8 per 1000 births)
- Ventricular Septal Defects = most common
- Atrial Septal Defects = 2nd most common
What happens to the O2 concentration in the blood as a result of acyanotic defects?
O2 concentration in the blood is NOT lower than normal
What is an atrial septal defect?
How do they happen?
- An opening in the septum between the two atria, which persists after birth
- Foramen ovale doesn’t close so blood still flows between atria after birth
What is the function of the foramen ovale?
- Permits right to left shunting of oxygenated blood via the inferior vena cava
- Allows bypassing of pulmonary circulation
Why are atrial septal defects acyanotic?
- Pressure in left atrium is HIGHER than pressure in right atrium
- Flow is mostly left to right
- No mixing of deoxygenated blood with oxygenated blood when being pumped around circulation
Where do atrial septal defects most commonly occur?
- Foramen ovale = ostium secundum and is most common
- Ostium primum = inferior septum but is less common
What is a patent foramen ovale?
- Failure of the foramen ovale to close
- Higher left pressure causes functional closure = no symptoms
When may a patent foramen ovale become a problem?
- Could be a route of a venous embolism to reach systemic circulation
- If pressure on right side of heart increases transiently
- Causes a paradoxical embolism
What is a ventricular septal defect?
- An opening in the interventricular septum
- Usually in the membranous portion
Are ventricular septal defects usually problematic?
- Not usually
- Left side pressure is much higher than right so blood flows from left to right
What is the ductus arteriosus?
- A vessel in the foetus
- Shunts blood from the pulmonary artery to the aorta when lungs are non-functional
- Usually closes after birth when there is a drop in pulmonary artery pressure
What is a patent ductus arteriosus?
What are the effects?
- Ductus arteriosus fails to close
- Blood flows from the aorta to the pulmonary artery after birth
- A mechanical murmur is heard in both systole and diastole
When can a patent ductus arteriosus become a problem?
- Chronic left to right shunting = vascular remodelling of pulmonary circulation and ↑ pulmonary resistance
- If pulmonary resistance > systemic resistance then the shunt reverses
- Causes ↑ pressure in the right heart (Eisenmenger syndrome)
What is coarctation of the aorta?
What happens as a result?
- Narrowing of the aortic lumen around the ligamentum arteriosum
- ↑ afterload of left ventricle = LV hypertrophy
- Upper limb and head aren’t affected as blood supply emerges before coarctation
How can coarctation of the aorta be detected?
- Weak and delayed femoral pulse
- Upper body hypertension
(mild cases) - Severe cases = heart failure at birth
