Which of the following is most common type of atrial septum defect (ASD)?

Appeared in: NORCET-7 Mains-2024

Explanation

Ostium secundum is the most common type of ASD, accounting for approximately 90% of cases.
It is a defect located in the central part of the atrial septum, specifically in the region of the fossa ovalis.
This type arises from either insufficient growth of the septum secundum or excessive resorption of the septum primum during embryonic development.
Many ostium secundum defects are suitable for non-surgical closure using a percutaneous device.

Option A: Ostium primum is not the most common type, representing only about 5% of ASDs.
Option C: Sinus venosus defects are also not the most common, accounting for about 5% of ASDs.
Option D: This option is incorrect because a correct answer, Ostium secundum, is listed among the choices.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Types and prevalence of Atrial Septal Defect (ASD) as background academic context rather than a clinical decision trigger.
Accurate identification of the ASD type is crucial for treatment planning; ostium secundum defects are often amenable to percutaneous device closure, while primum and sinus venosus types typically require open-heart surgery.
Nurses monitor patients with large ASDs for signs of right-sided heart failure (e.g., edema, hepatomegaly) and atrial arrhythmias, which result from chronic right ventricular volume overload.
What if? If a patient with an ASD also presents with a cleft mitral valve, the diagnosis is more likely to be an ostium primum defect, which requires a different surgical approach than a secundum defect.

How to Approach the Question

First, identify the core of the question, which is asking for the 'most common' type of a specific medical condition (Atrial Septal Defect).
This is a factual recall question. Access your knowledge about congenital heart defects.
Recall the different anatomical classifications of ASD: ostium secundum, ostium primum, and sinus venosus.
Compare the prevalence of each type. Remember that 'secundum' is by far the most frequent.
Select the option that corresponds to the highest prevalence.

Concept Tested & Keywords

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E6 Pathology-Textbook of PATHOLOGYHarsh Mohan Part 2 (215-514) p. 1

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 564-566

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 437-439

Practise the full NORCET-7 Mains-2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.