Q21.21

Billable

Partial atrioventricular septal defect

HCC Category Mapping

RxHCCHCC 191 — Congenital Heart/Circulatory Disorders and Fontan Circulation

0.000

What This Code Means

A birth defect where there is a partial abnormal opening in the wall between the upper and lower heart chambers, typically involving the endocardial cushion tissue.

Coding Tips

•Partial atrioventricular septal defect (AVSD) may include a cleft mitral valve; document associated valve abnormalities
•Distinguish from complete AVSD which involves both atrial and ventricular septal defects

Clinical Significance

Partial atrioventricular septal defect involves incomplete development of the endocardial cushions with preservation of separate atrioventricular valves but abnormal leaflet morphology. This condition typically presents with less severe hemodynamic compromise than complete forms but still requires surgical intervention in most cases.

Documentation Requirements

✓Echocardiographic confirmation of partial defect
✓Assessment of mitral valve cleft and regurgitation
✓Evaluation of atrial septal component
✓Hemodynamic assessment and impact
✓Associated cardiac anomalies
✓Surgical intervention history and outcomes
✓Current valve function and regurgitation severity
✓Exercise tolerance and functional status

Commonly Confused Codes

Q21.22 — transitional atrioventricular septal defect Q21.23 — complete atrioventricular septal defect Q21.1 — atrial septal defect Q23.3 — congenital mitral insufficiency Q22.2 — congenital pulmonary valve insufficiency

Code Hierarchy

└Q21Congenital malformations of cardiac septa └Q21.2Atrioventricular septal defect └Q21.21Partial atrioventricular septal defect

└Q21.21Partial atrioventricular septal defect