What is Atrial Septal Defect?
Hole between septum between the 2 atria
What is the normal embryological formation of the Septum? (5 steps)
- At start, L + R atria are one
- 2 walls grow downwards from top of heart (aka Septum Primum n Secondum)
- 2 walls fuse together w the Endocardial cushion @ middle
- Small hole left in Septum Secondum called: Foramen Ovale
- Foramen Ovale normally closes at birth
What happens when Foramen Ovale doesn’t close?
Patent Foramen Ovale… aka ASD
What does ASD lead to in terms of blood movement?
Shunt… aka blood moving between 2 atria
What shunt is most common in ASD? Why?
Left to Right, bc pressure in LA higher than RA
Does the shunt in ASD lead to Cyanosis?
No
Why does the shunt in ASD not lead to Cyanosis?
Blood still continues to flow from Pulmonary vessels to Lungs to get oxygenated
What conditions can ASD lead to? (2 things)
- RHF
- Pulmonary HTN
(bc increased blood flow to R heart –> overload + strain to R heart)
What are the types of ASD? (5 things)
- Patent Foramen Ovale (most common)
- Ostium secondum defect
- Ostium primum defect
- Sinus venosus defect
- Coronary sinus defect
What are the RF for ASD? (5 things)
- FHx
- Maternal smoking in 1st trimester
- Maternal alcohol + cocaine
- Maternal DM
- Maternal rubella
What are the CF of ASD in kids? (5 things)
- Usually asymptomatic (n only picked up on Antenatal scans / newborn exams)
- SOB
- Difficulty feeding
- Poor weight gain
- LRTI
How can a asymptomatic ASD present later in adulthood? (3 things)
- SOB
- HF
- Stroke
What are the features of an ASD murmur? (4 points)
- Mid-systolic
- Crescendo-decrescendo
- Loudest @ Pulmonary valve
- Fixed split S2
What are some differentials that present similarly to ASD? (4 things)
- AVSD
- VSD
- Innocent murmur (more softer n nasheedical)
- Pulmonary Stenosis murmur (more turbulent)
What is the GOLD standard investigation for Dx an ASD?
Transthoracic Echocardiogram
What does a Transthoracic Echocardiogram tell you about the ASD? (3 things)
- Size
- Direction of blood flow (using Doppler)
- Pulmonary artery pressure
What other imaging can be used for ASD? (2 things)
- Cardiac MRI
- CXR
What will a Cardiac MRI tell you about the ASD? (2 things)
- Identifies RV overload (in large ASD)
- Pulmonary vs Systemic blood flow ratio (aka Qp/Qs)
What does the Pulmonary vs Systemic blood flow ratio (aka Qp/Qs) tell you about the ASD?
How significant shunt is
What will a CXR tell you about the ASD?
Identifies cardiomegaly
What size of ASD should be managed conservatively?
Under 5mm
What are the CONSERVATIVE Mx options for ASD in KIDS?
Watch n wait: should close within 12 months of birth
What is the CONSERVATIVE Mx options for ASD in ADULTS?
If no RHF CF –> ECHO every 2-3 yrs
What are the MEDICAL Mx options for ASD? (2 things)
- Anti-arrhythmics
- Anticoag
(b4 definitive surgery)
