2027 ICD-10-CM Diagnosis Code Q21.0Ventricular septal defect

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q21

ICD-10-CM Q21.0
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Q21.0 is a billable ICD-10-CM diagnosis code for ventricular septal defect. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 306 through 307, 791, 793. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 89 closely related codes. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Q21.0 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 191 for payment year 2027.

Code Identity

ICD-10-CM Code
Q21.0
Billable Status
Yes — Valid for Submission
Code Describes
Ventricular septal defect
Short Description
Ventricular septal defect
Same as the full description in the CMS dataset.
Parent Code
Q21
Congenital malformations of cardiac septa

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ20-Q28Congenital malformations of the circulatory system
CategoryQ21Congenital malformations of cardiac septa
This CodeQ21.0Ventricular septal defect

Present on Admission (POA)Billing

Q21.0 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the circulatory system (Q20-Q28).

Medicare Risk Adjustment (HCC)Billing

Q21.0 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Part D (RxHCC)
RxHCC 191 — Ventricular Septal Defect and Major Congenital Heart Disorders
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Absent left sided atrioventricular connection
  • Absent pulmonary valve syndrome
  • Absent pulmonary valve syndrome with ventricular septal defect of non Fallot type
  • Acquired subaortic stenosis
  • Acquired subaortic stenosis associated with functionally univentricular heart
  • Acquired subaortic stenosis due to restrictive ventricular septal defect associated with functionally univentricular heart
  • Anterior muscular trabecular ventricular septal defect
  • Aortic valve overriding ventricular septum
  • Atrioventricular septal defect with additional muscular ventricular septal defect
  • Central basal perimembranous ventricular septal defect
  • Common atrioventricular-type ventricular septal defect
  • Concordant atrioventricular connections
  • Confluent muscular ventricular septal defect
  • Congenital abnormality of truncal valve
  • Congenital abnormality of ventricles and ventricular septum
  • Congenital absence of pulmonary valve
  • Congenital anomaly of atrioventricular septum
  • Congenital atresia of pulmonary valve
  • Congenital prolapse of aortic valve
  • Congenital subaortic stenosis
  • Congenital subaortic stenosis due to restrictive ventricular septal defect associated with functionally univentricular heart
  • Congenital ventricular septal defect
  • Discordant ventriculoarterial connection
  • Double outlet right ventricle
  • Double outlet right ventricle with doubly committed ventricular septal defect
  • Double outlet right ventricle with doubly committed ventricular septal defect and pulmonary stenosis
  • Double outlet right ventricle with noncommitted ventricular septal defect
  • Double outlet right ventricle with subaortic or doubly committed ventricular septal defect and pulmonary stenosis Fallot type
  • Double outlet right ventricle with subaortic or doubly committed ventricular septal defect without pulmonary stenosis - ventricular septal defect type
  • Double outlet right ventricle with subaortic ventricular septal defect
  • Double outlet right ventricle with subaortic ventricular septal defect without pulmonary stenosis
  • Double outlet right ventricle with subpulmonary ventricular septal defect
  • Double outlet ventriculoarterial connections
  • Doubly committed juxta-arterial outlet ventricular septal defect with anteriorly malaligned outlet septum
  • Doubly committed juxta-arterial outlet ventricular septal defect with perimembranous extension
  • Doubly committed juxta-arterial outlet ventricular septal defect with perimembranous extension and anteriorly malaligned outlet septum
  • Doubly committed juxta-arterial outlet ventricular septal defect with perimembranous extension and posteriorly malaligned outlet septum
  • Doubly committed juxta-arterial outlet ventricular septal defect with posteriorly malaligned outlet septum
  • Doubly committed juxta-arterial ventricular septal defect with anteriorly malaligned fibrous outlet septum and muscular postero-inferior rim
  • Doubly committed subarterial ventricular septal defect
  • Doubly committed subarterial ventricular septal defect with membranous septum extension
  • Doubly committed subarterial ventricular septal defect with muscular posterior inferior rim
  • Doubly committed ventricular septal defect in double outlet ventriculoarterial connection
  • Eisenmenger ventricular septal defect
  • Endocardial cushion defect
  • Functionally univentricular heart
  • Giant ventricular septal defect
  • Hemodynamically insignificant ventricular septal defect
  • Hypoplasia of infundibular septum
  • Infective endocarditis at site of patch of ventricular septal defect
  • Infective endocarditis at site of ventricular septal defect
  • Inferior muscular trabecular ventricular septal defect
  • Laubry Pezzi syndrome
  • Left ventricular-right atrial communication
  • Membranous ventricular septum defect
  • Multiple muscular ventricular septum defect
  • Multiple ventricular septal defects
  • Muscular ventricular septal defect in apical trabecular septum
  • Muscular ventricular septal defect in central trabecular septum
  • Muscular ventricular septal defect in inlet septum
  • Muscular ventricular septal defect in marginal septum
  • Muscular ventricular septal defect in outlet septum
  • Muscular ventricular septal defect in trabecular septum
  • Muscular ventricular septal defect opening to right ventricular inlet
  • Muscular ventricular septum defect
  • Non-restrictive ventricular septal defect
  • Outlet ventricular septal defect with anteriorly malaligned outlet septum
  • Outlet ventricular septal defect with posteriorly malaligned outlet septum
  • Perimembranous inlet ventricular septal defect
  • Perimembranous inlet ventricular septal defect with atrioventricular septal malalignment
  • Perimembranous outlet ventricular septal defect with anteriorly malaligned outlet septum
  • Perimembranous outlet ventricular septal defect with posteriorly malaligned outlet septum
  • Perimembranous ventricular septal defect
  • Perimembranous ventricular septal defect with extension to all right ventricular components
  • Perimembranous ventricular septal defect with extension to right ventricular inlet
  • Perimembranous ventricular septal defect with extension to right ventricular outlet
  • Perimembranous ventricular septal defect with extension to right ventricular trabecular component
  • Pulmonary atresia and ventricular septal defect with aorta from left ventricle
  • Pulmonary atresia and ventricular septal defect with aorta from right ventricle
  • Pulmonary atresia with ventricular septal defect
  • Residual ventricular septal defect
  • Roger's disease
  • Single muscular ventricular septum defect
  • Spontaneous closure of ventricular septal defect
  • Spontaneous closure of ventricular septal defect due to fibromuscular reaction
  • Spontaneous closure of ventricular septal defect due to tissue of membranous septum
  • Spontaneous reduction in size of ventricular septal defect
  • Spontaneous reduction in size of ventricular septal defect due to accessory tissue of atrioventricular valve
  • Spontaneous reduction in size of ventricular septal defect due to fibromuscular reaction
  • Spontaneous reduction in size of ventricular septal defect due to prolapse of cusp of aortic valve
  • Spontaneous reduction in size of ventricular septal defect due to tissue of membranous septum
  • Subaortic stenosis due to restrictive ventricular septal defect in functionally univentricular heart
  • Transposition of great arteries with concordant atrioventricular connections and ventricular septal defect
  • Transposition of great arteries with concordant atrioventricular connections and ventricular septal defect and left ventricular outflow tract obstruction
  • Ventricular septal abnormality
  • Ventricular septal defect
  • Ventricular septal defect between left ventricle and right atrium
  • Ventricular septal defect of inlet of right aspect of ventricular septum
  • Ventricular septal defect with absent outlet septum and overriding truncal valve
  • Ventricular septal defect with absent outlet septum and overriding truncal valve with extension of membranous septum
  • Ventricular septal defect with absent outlet septum and overriding truncal valve with inferior muscular rim
  • Ventricular septal defect with anterior malaligned outlet septum with overriding aortic valve
  • Ventricular septal defect with anterior malaligned outlet septum with overriding pulmonary valve
  • Ventricular septal defect with malaligned outlet septum
  • Ventricular septal defect with malaligned outlet septum to left
  • Ventricular septal defect with malaligned outlet septum to right
  • Ventricular septal defect with posterior malaligned outlet septum with overriding aortic valve
  • Ventricular septal defect with posterior malaligned outlet septum with overriding pulmonary valve

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Q21.0: its own notes plus those printed at Q21 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Roger's disease

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Q21 Congenital malformations of cardiac septa applies to 17 codes
  • acquired cardiac septal defect (I51.0)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • inborn errors of metabolism (E70-E88)

Notes

General instructions on how these codes are used.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • Codes from this chapter are not for use on maternal records

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Q21.0, its category, or a range that includes it.

Use Additional Code 1

These codes say to use an additional code from the note, and Q21.0 is one of the codes named.

  • Q87.88 CTNNB1 syndrome
    congenital heart malformations (Q20.0-Q24.9) names Q20.0-Q24.9, which includes this code

Code Also 2

These codes say Q21.0 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • I27.83 Eisenmenger's syndrome
    ventricular septal defect (Q21.0)
  • Q87.85 MED13L syndrome
    congenital malformations of cardiac septa (Q21.-) names Q21.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MAL001
Cardiac and circulatory congenital anomalies
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Heart Septal Defects, Ventricular

    developmental abnormalities in any portion of the ventricular septum resulting in abnormal communications between the two lower chambers of the heart. classification of ventricular septal defects is based on location of the communication, such as perimembranous, inlet, outlet (infundibular), central muscular, marginal muscular, or apical muscular defect.

Patient EducationClinical

Congenital Heart Defects

Congenital heart defects (CHDs) are problems with the structure of the heart. "Congenital" means that that the problems are present at birth. These defects happen when a fetus's heart doesn't develop normally during pregnancy. Congenital heart defects are the most common type of birth defect.

The full article covers:

  • What are congenital heart defects?
  • What causes congenital heart defects?
  • Who is more likely to have a baby with a congenital heart defect?
  • What are the symptoms of congenital heart defects?
  • What other problems do congenital heart defects cause?
  • How are congenital heart defects diagnosed?
  • What are the treatments for congenital heart defects?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert Q21.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
745.4 Ventricular sept defect
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Q21.0Overview

What is the ICD-10 code for ventricular septal defect?

The ICD-10-CM code for ventricular septal defect is Q21.0 (sometimes written as Q210). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Q21.0 (Congenital malformations of cardiac septa) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report ventricular septal defect on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Q21.0 group to?

When ventricular septal defect is the principal diagnosis on an inpatient stay, it groups to MS-DRG 306, 793, 791, 307, with relative weights from 0.9146 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q21.0 a CC or MCC?

CMS lists Q21.0 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 89 closely related codes in its exclusion list.

Is Q21.0 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for ventricular septal defect on inpatient claims. The code appears in the Congenital malformations of the circulatory system (Q20-Q28) range of the CMS exempt list.

Does Q21.0 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: Q21.0 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 191 (Ventricular Septal Defect and Major Congenital Heart Disorders).