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  5. Congenital malformations of cardiac septa (Q21)

Congenital malformations of cardiac septa (Q21)

ICD-10 codes Q21 cover congenital malformations of the cardiac septa, which are defects in the heart's wall separating its chambers. These codes are essential for identifying specific types of septal defects present at birth.

The primary conditions classified under Q21 include ventricular septal defect (Q21.0), known also by terms like supracristal or perimembranous ventricular septal defect, which involve holes in the septum between the heart’s ventricles. Atrial septal defects (Q21.1 to Q21.19) represent gaps in the wall between atria and include types such as secundum atrial septal defect (ostium secundum), patent foramen ovale, and sinus venosus defects. The atrioventricular septal defects (Q21.2 series) involve abnormalities of the septum and valves between atria and ventricles and have synonyms like endocardial cushion defect. Complex defects like tetralogy of Fallot (Q21.3) combine several malformations. Aortopulmonary septal defect (Q21.4) and other rare malformations (Q21.8) are also coded here. The unspecified code Q21.9 is used when the precise defect isn’t clearly identified. These ICD-10 codes help healthcare providers accurately classify congenital septal heart defects for diagnosis, treatment, and documentation.

Instructional Notations

Type 1 Excludes

A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.

  • acquired cardiac septal defect I51.0

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

Aortopulmonary Septal Defect

A developmental abnormality in which the spiral (aortopulmonary) septum failed to completely divide the TRUNCUS ARTERIOSUS into ASCENDING AORTA and PULMONARY ARTERY. This abnormal communication between the two major vessels usually lies above their respective valves (AORTIC VALVE; PULMONARY VALVE).

Double Outlet Right Ventricle

Incomplete transposition of the great vessels in which both the AORTA and the PULMONARY ARTERY arise from the RIGHT VENTRICLE. The only outlet of the LEFT VENTRICLE is a large ventricular septal defect (VENTRICULAR SEPTAL DEFECTS or VSD). The various subtypes are classified by the location of the septal defect, such as subaortic, subpulmonary, or noncommitted.

Endarteritis

Inflammation of the inner endothelial lining (TUNICA INTIMA) of an artery.

Tetralogy of Fallot

A combination of congenital heart defects consisting of four key features including VENTRICULAR SEPTAL DEFECTS; PULMONARY STENOSIS; RIGHT VENTRICULAR HYPERTROPHY; and a dextro-positioned AORTA. In this condition, blood from both ventricles (oxygen-rich and oxygen-poor) is pumped into the body often causing CYANOSIS.

Tunica Intima

The innermost layer of an artery or vein, made up of one layer of endothelial cells and supported by an internal elastic lamina.