MCQs on Restrictive Atrial Septal Defect (ASD)
MCQs on Restrictive Atrial Septal Defect (ASD)
ASD Flow across the defect in restrictive defect is determined largely by
[A] Size of the ASD
[B] Ventricular compliance
[C] Atrial compliance
[D] Ventricular afterload
ASD Flow across the defect
- Size of the ASD itself helps to determine the volume of shunting.
- If the ASD is large, the defect creates little or no resistance to flow. Blood flow across the defect in diastole is determined entirely by the relative properties of the ventricles as above.
- With a smaller, restrictive defect, blood flow is limited by the resistance of the ASD itself, no matter how large the difference in ventricular compliance.
MCQs on Restrictive Atrial Septal Defect (ASD)
1. What best defines a restrictive atrial septal defect (ASD)?
A. A defect that only allows right-to-left shunting
B. A small ASD with limited left-to-right flow
C. An ASD that causes severe pulmonary hypertension
D. A completely closed septum between atria
Explanation
Restrictive ASDs are small or partially obstructed defects with limited left-to-right blood flow across the atrial septum.2. What is the most common hemodynamic consequence of a restrictive ASD?
A. Severe left atrial dilation
B. Severe right heart failure
C. Minimal or no right atrial enlargement
D. Cyanosis and clubbing
Explanation
Restrictive ASDs result in only small shunts, often not causing significant right heart enlargement.3. Which diagnostic tool is most commonly used to detect a restrictive ASD?
A. Chest X-ray
B. Transthoracic echocardiography (TTE)
C. Electrocardiogram
D. Holter monitor
Explanation
Transthoracic echocardiography (TTE) with Doppler is the primary non-invasive test to evaluate atrial septal defects.4. A restrictive ASD is least likely to cause:
A. Murmur on auscultation
B. Eisenmenger syndrome
C. Mild dyspnea
D. Paradoxical embolism
Explanation
Eisenmenger syndrome requires a large, non-restrictive shunt leading to pulmonary hypertension; restrictive ASDs do not cause this.5. What kind of murmur is sometimes heard in patients with restrictive ASDs?
A. Continuous machinery murmur
B. Fixed split S2 with systolic ejection murmur
C. Diastolic rumble
D. Pansystolic murmur at apex
Explanation
A fixed split of the second heart sound with a soft systolic murmur due to increased flow across the pulmonary valve may be present.6. Which type of ASD is most likely to be restrictive?
A. Sinus venosus ASD
B. Ostium secundum ASD
C. Ostium primum ASD
D. Coronary sinus ASD
Explanation
Ostium secundum ASDs are the most common and can sometimes be small or restrictive in size.7. What is the usual clinical presentation of a small, restrictive ASD in childhood?
A. Cyanosis and fatigue
B. Severe failure to thrive
C. Asymptomatic or incidental murmur
D. Signs of congestive heart failure
Explanation
Many small ASDs are asymptomatic in early life and may be detected as incidental murmurs.8. Which condition increases the risk of paradoxical embolism in a restrictive ASD?
A. Left bundle branch block
B. Atrial fibrillation
C. Transient right atrial pressure elevation
D. Mitral stenosis
Explanation
Right atrial pressure can transiently exceed left atrial pressure (e.g., during Valsalva), enabling right-to-left shunting and risk of embolism.9. Which of the following is true regarding the management of restrictive ASDs?
A. Always require surgical closure
B. Must be closed before age 2
C. Often monitored without intervention
D. Require anticoagulation from birth
Explanation
Most restrictive ASDs are hemodynamically insignificant and monitored unless symptoms develop.10. What echocardiographic feature suggests a restrictive ASD?
A. Large septal opening with low velocity flow
B. Small defect with high-velocity color Doppler jet
C. Right-to-left bubble contrast at rest
D. Left atrial thrombus
Explanation
A small ASD with high velocity jet flow seen on Doppler indicates a restrictive defect.11. What is the typical direction of blood shunting in a restrictive ASD?
A. Right-to-left only
B. Left-to-right
C. Bidirectional with predominant right-to-left
D. No shunting
Explanation
Most ASDs, including restrictive ones, shunt blood from left atrium to right atrium due to pressure gradient.12. Which physical sign may raise suspicion of an ASD in an asymptomatic patient?
A. Loud S1
B. Fixed splitting of second heart sound
C. Diastolic click
D. Opening snap
Explanation
Fixed splitting of S2 is a hallmark of ASD due to prolonged right ventricular systole.13. Which test can confirm a small right-to-left shunt in a restrictive ASD?
A. ECG
B. Chest CT
C. Bubble contrast echocardiogram
D. Holter monitor
Explanation
Bubble contrast echo helps detect small shunts, including transient right-to-left ones.14. When is intervention typically considered for a restrictive ASD?
A. Immediately at diagnosis
B. If child is underweight
C. Once patient reaches adulthood
D. If symptomatic or with evidence of embolism
Explanation
Intervention is based on symptoms or complications such as embolic stroke.15. Which of the following is NOT a typical feature of restrictive ASD?
A. Limited flow across atrial septum
B. Often asymptomatic
C. Associated with Eisenmenger syndrome
D. Causes minimal right heart enlargement
Explanation
Eisenmenger syndrome is not a feature of restrictive ASD due to limited pulmonary overcirculation.16. Restrictive ASDs are more likely to be detected in:
A. Neonatal period due to heart failure
B. Later in life during routine examination
C. Antenatal screening always
D. Immediately after birth
Explanation
They are often asymptomatic and picked up later due to subtle murmurs or stroke evaluations.17. Which complication is specifically linked to a small ASD with transient right-to-left shunting?
A. Right ventricular failure
B. Paradoxical embolism
C. Infective endocarditis
D. Arrhythmia
Explanation
Small shunts with intermittent right-to-left flow (e.g. during straining) can allow emboli to bypass lungs, causing stroke or embolism.18. A patient with a restrictive ASD and stroke should be evaluated for:
A. Carotid artery dissection
B. Atrial fibrillation
C. Paradoxical embolism through the ASD
D. Hypercoagulable state only
Explanation
Restrictive ASDs can be pathways for emboli from venous to arterial system causing stroke — paradoxical embolism.19. Which of the following statements is TRUE regarding restrictive ASDs?
A. They always need device closure
B. They may not require any treatment
C. They usually lead to heart failure
D. They typically progress to larger ASDs
Explanation
Most restrictive ASDs remain small and do not require treatment unless symptomatic or at risk of embolism.20. In adults, what incidental finding may lead to the discovery of a restrictive ASD?
A. Persistent dry cough
B. Recurrent urinary tract infections
C. Chronic anemia
D. Embolic stroke in a young person
Explanation
Many restrictive ASDs are found after evaluating young patients with unexplained stroke due to paradoxical embolism.1. What is a restrictive atrial septal defect?
- A small or partially obstructed opening in the atrial septum
- Allows limited left-to-right shunting
- Causes minimal hemodynamic disturbance
- May be covered by a flap or valve-like tissue
- Often diagnosed incidentally on echocardiography
2. What are common symptoms associated with restrictive ASDs?
- Often asymptomatic
- Mild exertional dyspnea in some cases
- Occasional palpitations
- Rare fatigue or chest discomfort
- No signs of cyanosis or heart failure
3. How is a restrictive ASD diagnosed?
- Transthoracic echocardiography (TTE) is the first-line tool
- Color Doppler shows limited shunting
- Bubble contrast study may demonstrate delayed shunting
- Transesophageal echo (TEE) provides detailed anatomy
- Cardiac MRI can help in complex or borderline cases
4. What are the auscultatory findings in restrictive ASD?
- May be normal
- Sometimes soft systolic ejection murmur
- Fixed splitting of second heart sound (S2) possible
- No diastolic murmur usually
- Murmur intensity doesn’t correlate with shunt size
5. How does restrictive ASD differ from large ASD physiologically?
- Restrictive ASD causes limited blood flow
- No significant right heart volume overload
- Low risk of pulmonary hypertension
- Rarely causes symptoms or failure
- Large ASDs lead to significant shunting and complications
6. What is the typical management for restrictive ASD?
- Usually no intervention needed
- Periodic follow-up with echocardiography
- Closure considered if associated with paradoxical embolism
- Lifestyle is typically unrestricted
- Educate patient on signs of complications
7. Can restrictive ASD cause complications? If so, which?
- Rare, but possible
- Paradoxical embolism through transient right-to-left shunt
- Arrhythmias like atrial fibrillation
- Stroke or TIA if embolism occurs
- Residual shunt post device closure (in rare cases)
8. What is the role of a bubble study in restrictive ASD?
- Confirms presence of a shunt
- Identifies right-to-left flow during Valsalva
- Helps differentiate PFO from ASD
- More sensitive with TEE than TTE
- Used when embolic stroke is suspected
9. What conditions can mimic a restrictive ASD?
- Patent Foramen Ovale (PFO)
- Fenestrated atrial septal aneurysm
- Small sinus venosus defects
- Double atrial septum
- Incomplete closure after device repair
10. When should a restrictive ASD be closed?
- History of cryptogenic stroke
- Evidence of paradoxical embolism
- Right heart dilation on imaging
- Associated arrhythmias
- Patient preference after informed discussion
1. Definition
A restrictive ASD is a small or partially obstructed atrial septal defect that limits the flow of blood between the atria.2. Hemodynamics
Left-to-right shunting is minimal due to limited defect size or restricted flow.3. Clinical Severity
Usually less severe than large ASDs and often asymptomatic.4. Common Symptoms
May include mild dyspnea, fatigue, or palpitations; often asymptomatic.5. Auscultation Findings
May reveal fixed split of second heart sound and soft systolic murmur.6. Diagnostic Modality
Transthoracic echocardiography (TTE) is the first-line diagnostic tool.7. Role of Doppler
Doppler echocardiography helps identify the direction and velocity of flow.8. Use of Bubble Study
Assesses for shunting, especially in paradoxical embolism cases.9. TEE Utility
Transesophageal echocardiography (TEE) gives better anatomical detail.10. Associated Structures
May be associated with septal aneurysm or valve-like flap over defect.11. Right Heart Changes
Minimal or no right atrial or ventricular enlargement typically seen.12. Risk of Pulmonary Hypertension
Very low risk due to limited shunting.13. Differential Diagnosis
Includes PFO, sinus venosus defect, or fenestrated septal aneurysm.14. ECG Findings
Often normal or may show mild right atrial enlargement.15. Chest X-ray
Typically normal; rarely shows signs of right heart enlargement.16. Management Approach
Conservative management with observation is usually sufficient.17. Indications for Closure
Considered if there is embolic event, right heart strain, or patient preference.18. Complications
Rarely causes stroke (via paradoxical embolism) or arrhythmias.19. Prognosis
Excellent in most cases with regular monitoring.20. Follow-up
Periodic echocardiography to monitor for any changes in defect size or heart dimensions.
Trivial: Less than 3 mm.
Small: Between 3 mm and less than 6 mm.
Moderate: Between 6 mm and less than 12 mm.
Large: Greater than or equal to 12 mm.
| Feature | Restrictive ASD | Non-Restrictive ASD |
|---|---|---|
| Defect Size | Small or partially covered | Moderate to large |
| Shunt Volume | Minimal (limited left-to-right shunt) | Large (significant left-to-right shunt) |
| Symptoms | Often asymptomatic | Dyspnea, fatigue, palpitations common |
| Right Heart Dilation | Minimal or absent | Common due to volume overload |
| Pulmonary Hypertension | Rare | Can develop over time |
| Heart Sounds | Soft murmur or none; subtle fixed split S2 | Prominent murmur with widely fixed split of S2 |
| ECG Findings | Often normal; mild right atrial enlargement | Right axis deviation, RV hypertrophy possible |
| Chest X-ray | Typically normal | Cardiomegaly and prominent pulmonary vessels |
| Echocardiography Findings | Small shunt; possibly flap or aneurysmal septum | Large shunt; clear left-to-right flow |
| Bubble Contrast Study | Minimal or delayed shunting | Immediate contrast transfer |
| TEE (Transesophageal Echo) | May be needed to confirm small defect | Confirms size and location for closure planning |
| Management | Observation; closure rarely needed | Often requires closure (device or surgery) |
| Complications | Rare; may cause paradoxical embolism | Paradoxical embolism, arrhythmias, right heart failure |
| Prognosis | Excellent with monitoring | Risk of complications if untreated |
| Indications for Closure | Cryptogenic stroke, embolism, or patient choice | Size >10mm, symptoms, right heart strain |
| Age at Diagnosis | Often incidental in adulthood | Detected in childhood or due to adult symptoms |
| Associated Lesions | Septal aneurysm, flap-valve PFO | Sinus venosus, primum ASD |
| Impact on Exercise Tolerance | Usually preserved | Reduced due to over-circulation of lungs |
| Long-Term Follow-Up | Routine echo monitoring | Closer follow-up; risk of pulmonary hypertension |
| Surgical Need | Rare | Common in symptomatic or large defects |
