Atrial septal defect Flashcards
What is the second most common congenital heart defect?
Atrial septal defect
What is ASD?
Septum between left and right atrium is not formed completely
What shunt occurs in ASD?
Left to right shunt
Pressure in left atrium is greater than in the right
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
What might happen to the ASD if it is very small?
May close on its own
How many live births have an ASD?
9 in 1000
What percentage of CHDs do ASDs account for?
5-10%
Which sex is more prone to ASD and which one in particular?
Female
Ostium secundum
Describe the pathophysiology of ASD in terms of atrial septum embryology
Formed from 2 separate endocardial cushions in the 4th week of gestation
Primary atrial septum = septum primum (grows cranial to caudal), this closes off the ostium primum
The ostium secundum develops again from the atrial roof and grows downwards towards the septum primum
Foramen ovale = space between the septum primum and secundum
When does the foramen ovale close?
Shortly after birth
Why does the foramen ovale close?
Change in vascular resistance
Systemic BP increases as pulmonary pressure decreases with a decrease in RA pressure
List the 5 types of ASD in order of how commonly they occur
Patent foramen ovale Ostium secundum defect Ostium primum defect Sinus venosus defect Coronary sinus defect
Describe ostium secundum defect
When there is incomplete occlusion of ostium secundum by septum secundum or too much reabsorption of septum primum by the atrial roof
Describe ostium primum defects
When septum primum fails to fuse with the endocardial cushions allowing blood to travel from LA to RA
Name and describe the two types of ostium primum defects
Complete AVSD - Common AV valve but spanning from atria to ventricles
Partial AVSD - Defect just of the ostium primum with intact ventricular septum
What can sinus venous defects be split into?
Superior
Inferior
Describe superior sinus venous defect
When Superior vena cava opening runs on top of oval fossa of atrial septum
Renders SVC draining blood from both LA and RA
Describe inferior sinus venous defect
Less common
Occurs with IVC orifice overrides LA and RA
Can coexist with abnormal communication between IVC and right superior pulmonary vein
Describe coronary venous sinus defect
Absence of a roof in the coronary sinus
Partial or focal
Allowing for transmission between coronary sinus and left atrium
List the risk factors for atrial septal defect
FH Maternal smoking in 1st trimester Maternal cocaine and alcohol use Maternal diabetes Maternal rubella
What inheritance pattern does ASD present?
Autosomal dominant
What congenital conditions are ASDs linked with?
Treacher Collins syndrome
Thrombocytopenia absent radii (TAR) syndrome
List the symptoms of large ASD in children
Tachypnoea
Poor weight gain
Recurrent chest infections
List the symptoms of untreated large ASDs in adults
Exercise intolerance Palpitations Recurrent chest infections Fatigue Syncope
What examination findings are there of an ASD?
Murmur - soft ejection systolic murmur, best heard over the pulmonary region, wide, fixed splitting second heart sound, diastolic rumble in the lower left sternal edge
What is the differential of a ASD?
AVSD
VSD
Innocent murmur
Pulmonary stenosis
What is an innocent murmur?
Soft and musical
Describe the pulmonary stenosis murmur
More turbulent
What investigations would you do for an ASD?
ECG
Transthoracic echocardiogram
Cardiac MRI and CT
CXR
What are some possible ECG changes in a large ASD?
Tall P wave - RA enlargement
Right bundle branch block
Right axis deviation
Atrial fibrillation or flutter
What information does a transthoracic echocardiogram show?
Size of ASD
Direction of blood flow
What can cardiac MRI measure?
Pulmonary vs systemic blood flow ratio
Informs us of how significant the shunt is
Describe the management of ASD
If ASD <15mm then spontaneous closure should occur within 12 months of birth
In adults with no signs of heart failure and a small defect - continue to monitor by echo every 2-3yrs
If presenting with arrhythmia, control rhythm with drugs and anticoagulated before definitive surgical treatment
Diuretics for children with heart failure
Surgical closure is the definitive management - patients with ASD>1cm - percutaneous or open
When is surgical closure not recommended?
For patients with pulmonary hypertension as this can induce RV failure if the ASD closes up
What does percutaneous closure require?
Adequate septum to be present in order to hold device in place
List the complications of percutaneous closure
Arrhythmia
Atrioventricular block
Thromboembolism
List the indications for surgical closure
TIA/stroke
Ostium primum defects
Sinus venous defects
Coronary sinus defects
What are the complications of large atrial septal defects
Arrhythmia Pulmonary hypertension Eisenmenger syndrome Cyanosis Peripheral oedema TIA/stoke
What is the life expectancy for a child with an ASD diagnosed in childhood?
The same as normal
