Cardiology Coding Alert

Even one-to-one matches can hold surprises -- check the index for clarity.

When ICD-10 replaces ICD-9 in 2013, one lesson you'll need to remember is that inclusion lists may differ between the two code sets. That means that ICD- 9 and ICD-10 codes that appear to be twins may not apply to the same list of diagnoses.

Case in point: ICD-9 2011 code 745.4 (Ventricular septal defect) and ICD-10 2011 code Q21.0 (Ventricular septal defect) have the same code definition. Both reference ventricular septal defect (VSD), which involves at least one hole in the wall separating the ventricles of the heart. Despite the similarity in the code definitions, the inclusion lists for these codes are not identical.

ICD-9 coding rules: Code 745.4 has an inclusion note telling you the code is appropriate for Eisenmenger's defect or complex, Gerbode defect, interventricular septal defect, left ventricular-right atrial communication, or Roger's Disease.

ICD-10 changes: The inclusion list under Q21.0 shows only Roger's disease.

Because you will find differences in which diagnoses fall under similar ICD-9 and ICD-10 codes, the basic principle of checking both the index and the tabular list will be crucial for proper ICD-10 coding.

For example, if you look up Eisenmenger's defect (which falls under 745.4), you'll see that ICD-10 codes this defect to Q21.8 (Other congenital malformations of cardiac septa). And in another example of what's different, Eisenmenger's complex (which also falls under 745.4) is instead coded to I27.89 (Other specified pulmonary heart diseases) under ICD-10.

Documentation: If the patient has one of the named defects (for example, those listed in the ICD-9 inclusion list), documentation of that specific name will allow you to check the index to be sure you have the most appropriate ICD-10 code.

You'll also need documentation to include whether the VSD is congenital (existing at or before birth), due to myocardial infarction, or otherwise acquired (a reaction to environmental influences). ICD-10 directs you away from Q21.0 if the patient has an acquired septal defect (I51.0, Cardiac septal defect, acquired) or a VSD as a current complication of an acute myocardial infarction (I23.2, Ventricular septal defect as current complication following acute myocardial infarction).

Bonus tip: ICD-9 also has an exclusion list under 745.4, so you know not to use the code for common atrioventricular canal type (coded to 745.69, Other endocardial cushion defects) or single ventricle (coded to 745.3, Common ventricle) defects. ICD-10 does not have an excludes list for Q21.0, but those diagnoses still are coded elsewhere: Q21.2 (Atrioventricular septal defect) applies to the common atrioventricular canal and Q20.4 (Double inlet ventricle) applies to the single or common ventricle diagnosis.

Remember: When ICD-10 goes into effect on Oct. 1, 2013, you should apply the code set and official guidelines in effect for the date of service reported. Learn more at www.cms.gov/ICD10/ and www.cdc.gov/nchs/icd/icd10cm.htm#10update.