Atrial Septal Defect Flashcards
What is Atrial Septal Defect
- congenital heart defect
- a hole or opening in the septum (the wall) that divides the left and right atria
4 pathopysiologies
ASD pathophysiology
- Left-to-Right Shunt
- Volume Overload
- Increased Pulmonary Blood Flow
- Atrial Arrhythmias
What shunt occurs in ASD?
Left-to-Right shunt
Why do Left-to-Right shunt occur
Pressure in left atrium is greater than in the right
Where do the vol. overload occur in ASD?
Right ventricle
What can the vol. overload in the R ventricle lead to?
R sided hypertropy
R heart strain
Pulmonary HTN
R heart failure
What type of embolism occur in ASD?
Paradoxical embolism
Emoli travel from R –> L side
What complication can a DVT cause in ASD?
Stroke
At which part of the heart does O2 sat. increase
R atrium
R ventricle
Pulmonary artery
In terms of cyanosis, what is ASD?
Acyanotic congenital heart disease
Why is ASD acyanotic?
Oxygenated blood from left atrium is forced into the right atrium
ASD pathophysiology
- Septum primum grows and closes the ostium primum (1st opening) by fusing with the endocardial cushion
- A 2nd opening (ostium secundum) appears on the septum primum roof
- Septum secundum grows to cover the ostium secundum and leave a hole = Foramen ovale
- At birth, the septums fused with the endocardial cushion to close the foramen ovale
- Defects in the septum primum/secundum –> ASD
Describe ostium primum defects
When septum primum fails to fuse with the endocardial cushions allowing blood to travel from LA to RA
List the 3 types of ASD in the order of how commonly they occur
Patent foramen ovale
Ostium secundum
Ostium primum
ASD auscultation findings
- Ejection Systolic Murmurs
- Fixed splitting of 2nd HS
How does an emboli from DVT causes a stroke in ASD?
Emboli can travel through from the R sided of the heart to the L sided of the heart and enter systemic circulation –> to the brain
What imagina Ix is used to detect ASD?
Bubble Echo
Echo + inj. microbubbles
What causes the split 2nd HS in ASD?
- Prolonged right ventricular ejection time due to increased blood flow into the right ventricle.
- Delayed closure of the pulmonary valve (P2), creating a fixed split between A2 and P2
ASD Risk Factors
- Female
- Maternal alcohol consumption
ASD ECG findings
- Right Axis Deviation: right ventricular enlargement
- P Pulmonale (Tall, Peaked P Waves): L - R shunting –> right atrial enlargement
- RBBB: right ventricle may become enlarged or overworked
- Prolonged PR Interval: increased volume and pressure in the right atrium
- Atrial Arrhythmias: Atria dilatation –> AF, Atrial flutter
ASD Dx Ix
Echo
ASD Mx
- Active monitoring (small defects may close on their own)
- Percutaneous transvenous catheter closure (via the femoral vein)
- Open-heart surgery
What might happen to the ASD if it is very small?
May close on its own
