Atrial Septal Defect Flashcards
What are the clinical signs of an atrial septal defect?
- Wide, fixed splitting of S2
- Murmurs if shunt present - ESM over pulmonary area louder on inspiration
- Signs of pulmonary hypertension
- Functional TS (MDM at tricuspid area) - Eisenmenger shunt reversal (cyanosis and clubbing)
- Signs of heart failure
- Raised JVP
- Pulmonary area thrill - Complications of IE
- Syndromes: Down syndrome, thumb defect in Holt-Oram syndrome
What are the types of atrial septal defect?
-
Ostium secundum (90%): foramen ovale defect with no valvular involvement
- Mostly asymptomatic, if small < 2cm, normal life expentancy
- Larger defects - 2nd or 3rd decade dyspnoea, fatigue -
Ostium primum: anterior and inferior aspect with involvement of mitral and tricuspid valve
- Failure of fusion of septum primum with endocardial cushions
- A/w with atrioventricular septal defect and Down’s syndrome -
Sinus venosus type: defect in septum just below entrance of SVC
- Abnormal drainage of right pulmonary vein
- Inverted P wave in inferior leads - Coronary sinus defect: unroofed coronary sinus allowing blood shunting from LA to coronary sinus into RA
What are the complications of an atrial septal defect?
- Paradoxical embolus through patent foramen ovale
- Atrial arrhythmia
- Right ventricular dilatation and eventual right heart failure
- Eisenmenger’s syndrome (shunt reversal due to pulmonary hypertension)
How would you investigate a patient with an atrial septal defect?
ECG
- Secundum: partial RBBB, RAD
- Primum: LBBB, LAD, low atrial rhythm
- Sinus venosus: inverted P in inferior leads
- Pulmonary hypertension: p pulmonale, RVH
- Atrial fibrillation
CXR
- Cardiomegaly
- Pulmonary plethora (well visualised pulmonary arteries)
- Pulmonary hypertension: double heart border, prominent pulmonary trunk
- Small aortic knob
TTE
- Site, size and shunt calculation, shunt direction
- PASP
- Amenability to closure
Cardiac catheterisation
- Determines severity and direction of shunt
What are the indications and contraindications for closure of an atrial septal defect?
Indications:
- Symptomatic (embolus, breathless)
- Significant shunt
- Pregnancy
- Early childhood
Contraindications:
- Severe pulmonary hypertension
- Eisenmeinger’s syndrome
How do patients with ASD present?
Secundum
- Asymptomatic
- Symptomatic in 2nd/3rd decade: fatigue, dyspnoea, right heart failure, AF (due to atrial dilatation), recurrent pulmonary infection, paradoxical emboli, IE
Primum
- Similar symptoms + syncope (heart block)
What are the murmurs associated with ASD?
- Pulmonary ESM, tricuspid MDM: increased blood flow trough PV and TV due to left to right shunting
- Mitral MDM: Lutembacher’s syndrome (mitral valvulotomy causing iatrogenic ASD)
- MR, TR or VSD murmur: ostium primum type
- Fixed, wide splitting S2:
- Wide: left to right shunt overloads RV, increased venous return prolongs right heart emptying and delay in P2 closure
- Fixed: equalisation of RA and LA
What are causes of wide splitting S2?
- ASD
- VSD
- PR (increased RV volume)
- PS (increased RV pressure)
- RBBB (RV conduction delay)
- MR (increased LV emptying)
How do you differentiate flow murmur through PV vs PS murmur?
PS murmur has soft P2, delayed closure, varies with respiration
What is Tetralogy of Fallot?
- VSD
- RVH
- PS
- Overriding of aorta
What is Holt Oram syndrome?
- Autosomal dominant
- ASD secundum
- Hypoplastic thumb with accessory phalanx
How do you manage patient with ASD?
- Education and counselling
- Small and insignificant ASD: reassurance, asymptomatic, even pregnancy is well tolerated
- Larger defects or complications: avoid pregnancy (increased mortality) - Medical treatment for HF, AF
- Anticoagulation if bidirectional shunt to prevent strokes from paradoxical emboli
- Surgical closure
- Early childhood 5-10 years to prevent complications
- Large ASD or pulmonary to systemic flow ratio > 2
- Routine closure before pregnancy - Choice of surgery
- Transcatheter button or clam-shell devices
- Surgical closure
