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Q21.11 — Secundum atrial septal defect
Q21.11
What this code means
A secundum atrial septal defect is an opening in the wall between the heart's upper chambers, in its central (secundum) part.
Also called: secundum atrial septal defect, asd.
When this code is used
Used for secundum atrial septal defect.
Where it sits in ICD-10-CM
Code Q21.11 belongs to Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders, which covers codes Q00–QA1 in the FY2027 ICD-10-CM tabular list. The official description above is copied verbatim from the CDC/NCHS FY2027 code file.
Related anatomy
Frequently asked questions
What is ICD-10-CM code Q21.11?
Q21.11 is the ICD-10-CM diagnosis code for “Secundum atrial septal defect”. A secundum atrial septal defect is an opening in the wall between the heart's upper chambers, in its central (secundum) part.
When is code Q21.11 used?
Used for secundum atrial septal defect. It belongs to Chapter 17 of ICD-10-CM (Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders).
This guide explains ICD-10-CM codes in plain language for patients, students and other readers. It is educational information only — not coding, billing or medical advice. The code recorded for any real encounter is assigned from the full clinical documentation by the treating team and qualified coders, and only they can decide which code fits a specific case.