Q23.4 ICD-10-CA code: Hypoplastic left heart syndrome
Q23.4 is the ICD-10-CA code for “Hypoplastic left heart syndrome” in CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026.
Official description
Q23.4Hypoplastic left heart syndrome
ICD-10-CA · Canada · Also written Q234
Index terms
Entries in CIHI’s alphabetical index that lead to Q23.4. Searching the index by the condition the note names is how coders reach this code.
- Syndrome, hypoplastic left heart
- Hypoplasia, hypoplastic, left heart syndrome
- Atresia, atretic, mitral valve, in hypoplastic left heart syndrome
- Atresia, atretic, aortic (orifice) (valve), in hypoplastic left heart syndrome
- Hypoplasia, hypoplastic, aorta, aortic, valve, in hypoplastic left heart syndrome
- Hypoplasia, hypoplastic, aorta, aortic, ascending, in hypoplastic left heart syndrome
- Development, defective, congenital, left ventricle, in hypoplastic left heart syndrome
- Atresia, atretic, aortic (orifice) (valve), congenital with hypoplasia of ascending aorta and defective development of left ventricle (with mitral stenosis)
Notes for Q23.4
As CIHI prints them, with any note Q23.4 takes from the headings above it.
Includes
- Atresia, or marked hypoplasia of aortic orifice or valve, with hypoplasia of ascending aorta and defective development of left ventricle (with mitral valve stenosis or atresia).
Excludes
Conditions classified elsewhere.
- Inborn errors of metabolism (E70-E90)From Chapter 17: Congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
Where Q23.4 sits
- 1ChapterChapter 17: Congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
- 2Block Q20-Q28Congenital malformations of the circulatory system
- 3Category Q23Congenital malformations of aortic and mitral valves
- 4Valid code Q23.4Hypoplastic left heart syndrome
Source and release
- Data release
- ICD-10-CA · FY 2026–2027
- Effective date
- Apr 1, 2026
- Publisher
- CIHI
This page is built from the ICD-10-CA catalog that Vero Codes reads when it suggests codes: Canadian Institute for Health Information’s FY 2026–2027 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.
Frequently asked questions
What does ICD-10-CA code Q23.4 mean?
Q23.4 is the ICD-10-CA code for “Hypoplastic left heart syndrome” in CIHI’s ICD-10-CA FY 2026–2027 release.
Where is Q23.4 in ICD-10-CA?
Q23.4 sits under Q23 Congenital malformations of aortic and mitral valves, within Q20-Q28 Congenital malformations of the circulatory system, within Chapter 17: Congenital malformations, deformations and chromosomal abnormalities (Q00-Q99).
What coding notes apply to Q23.4?
ICD-10-CA lists Includes, Excludes notes for Q23.4, including those from the headings it sits under. They are listed on this page with where each one comes from.
Which ICD-10-CA release does this page use?
It uses CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026 to Mar 31, 2027. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.