Atrial Septal Defect

Question 1

Does Atrial Septal Defect present as a Cyanotic or Acyanotic CHD?

Answer 1

Acyanotic CHD. ASD is when the septum between the RA and LA is not completely formed. Due to the higher pressures in the LA, blood is forced through the LA to the RA
therefore, only oxygenated blood is passed throughout the body.

Question 2

What is the Pathophysiology of Atrial Septal Defect?

Answer 2

The atrial septum forms from two separate endocardial cushions. Septum Primum grows from the cranial to the caudal and closes of the ostium primum. Septum Secundum which grows and form the ostium secundum. The gap between the two is known as the foramen ovale.

Question 3

What are the 5 types of ASD?

Answer 3

1. Patent Foramen Ovale
2. Ostium Secundum Defect
3. Ostium Primum Defect
4. Sinus Venosus Defect
5. Coronary Sinus Defect

Question 4

What is an Ostium Secundum Defect?

Answer 4

This is when the septum secundum fails to fully close and therefore leaves a hole in the wall.

Question 5

What is an Ostium Primum Defect?

Answer 5

This is when the septum primum fails to fully close leaving a hole in the wall.

Question 6

What is a “Complete AVSD” - Ostium Primum Defect?

Answer 6

A common AV valve defect which spans from atrium to the ventricles

Question 7

What is a “Partial AVSD” - Ostium Primum Defect?

Answer 7

A partial AVSD is a defect of just the ostium primum with an intact ventricular septum

Question 8

What is a Sinus Venosus Defect - Superior?

Answer 8

When Superior Vena Cava runs on top of the oval fossa (foramen ovale remnant) of the atrial septum. This means that SVC drains into both the LA and the RA. Can have an abnormal communication between the SVC and the Right Superior Pulmonary Vein

Question 9

What is the Sinus Venosus Defect - Inferior?

Answer 9

When the Inferior Vena Cava overrides the LA and RA, can mean an abnormal communication between IVC and the Right Inferior Pulmonary Vein

Question 10

What is a Coronary Sinus Defect ?

Answer 10

This is an absence in the roof of the coronary sinus (unroofed coronary sinus defect), this can be partial/focal and allows transmission between the coronary sinus and the Left Atrium

Question 11

What are the Risk Factors for Atrial Septal Defects?

Answer 11

• Autosomal Dominance inheritance has a link with ostium secundum ASD clusters
  -Family History of ASD
  -Maternal RF: Maternal Smoking in 1st Trimester, Maternal Diabetes, Maternal Rubella, Maternal Drug Use (cocaine + alcohol)
  -Congenital Syndromes: Treacher- Collins Syndrome (a rare genetic condition affecting the way the face develops - cheekbones, jaws, ears and eyelids.
  Thrombocytopenia-absent radii syndrome (TAR syndrome) - (Rare genetic condition that is characterized by the absence of the radius bone in the forearm and a dramatically reduced platelet count.

Question 12

What are some of the symptoms of a large ASD in Paeds?:

Answer 12

• Tachypnoea
• Poor Weight Gain
• Recurrent Chest Infections

Question 13

What are some of the symptoms of untreated large ASDs in Adults?

Answer 13

• Exercise Intolerance
• Palpitations
• Recurrent Chest Infections
• Fatigue
• Syncope

Question 14

What is the finding of an ASD on Auscultation on examination?

Answer 14

• Soft, Systolic Ejection Murmur, Best heard over the Pulmonary Valve Region (2nd ICS)
• Wide, fixed split S2
• Diastolic Rumble in lower left sternal edge

Question 15

What are the Differential Diagnosis?

Answer 15

-Atrioventricular septal defect
- Ventricular septal defect
- Innocent Murmur
- Pulmonary Stenosis

Question 16

What are Bedside Tests that you would do for ASD?:

Answer 16

• ECG (normal in children with small ASD)
• ECG (in large ASD): Tall P wave, RBBB, RAD
• Adults = Atrial Fibrillation/ Atrial Flutter

Question 17

What are the Imaging or Invasive Tests that you would do for ASD?:

Answer 17

-TOE is the gold standard in diagnosing ASD (able to provide information on the size of ASD, direction of blood flowing through the defect)
-CXR - cardiomegaly
- Cardiac MRI - can measure pulmonary vs systemic blood flow ratio (Qp/Qs) this informs us how significant the ASD shunt is.

Question 18

What is the management of ASD?

Answer 18

• Initial Managment: - Conservative: if ASD <5mm, spontaneous closure within 12 months of birth.
• In adults: if no signs of R heart failure + small defect = monitor every 2/3 years with ECHO. if presenting with arrhythmia, control rhythm with drugs & anticoagulated before definitive surgical treatment
• Medical: heart failure = diuretics
• Definitive Managment: surgical closure is the definitive treatment (patients with ASD >1cm). Surgery can be carried out percutaneously (requires adequate septum to be present in order for the device to hold in place) or open chest (central sternotomy) - not recommended where pulmonary hypertension is present as this can induce RV failure if the ASD closes up

Question 19

What are the Complications of Percutaneous Closure?

Answer 19

• Arrhythmias
• AV block
• Thromboembolism (VTE aspirin)

Question 20

What are the indications for surgical closure?

Answer 20

• TIA/Stroke
• Ostium Primum Defects
• Sinus Venous Defects
• Coronary Sinus Defects

Question 21

What are the Complications of large untreated ASDs?

Answer 21

• Arrhythmias (caused by atrial stretch leading to abnormal foci development)
• Pulmonary Hypertension
• Eisenmenger Syndrome
• Peripheral Oedema
• TIA/ Stroke