Cracking the code: Coronary artery bypass graft

Just like I stated in my last blog, accurate ICD-10-PCS code assignment requires the coder to have a good understanding of coding guidelines, anatomy, physiology, and medical terminology, as well as the ability to decipher the operative report. Coronary artery bypass grafting procedures are no exception. 

Coronary artery bypass grafting creates an alternative path within diseased heart vessels, allowing improved blood flow to the myocardium. This involves taking a healthy blood vessel from another part of the body to use as the conduit or graft material. Saphenous veins and the left internal mammary artery are commonly used as graft material. The right internal mammary artery and the radial artery may also be used. This graft material is sutured to the coronary artery below the diseased area, creating a new blood flow route. 

To properly code these procedures, you must identify the number of coronary arteries that were bypassed (Body Part), the type of graft material used (Device) and the site of anastomosis (Qualifier). ICD-10-PCS Official Guidelines for Coding and Reporting B3.6b states that for coronary artery bypass procedures, the body part character is used to identify the number of coronary arteries bypassed to, and the qualifier character specifies the vessel bypassed from. Guideline B3.6c instructs us to use a separate procedure code for each coronary artery that uses a different device and/or qualifier. 

Below is an excerpt from the 021 table depicting the most common device and qualifier character options.

021 Table

To properly assign the correct body part character, the coder must know the device(s) and qualifier(s) used, so let’s review the device character options. 

Device character 9 — Autologous Venous Tissue is assigned when the saphenous vein is harvested (i.e., complete removal from its native location) and used as the graft material. The common language used to describe this is saphenous vein graft (SVG) to obtuse marginal (OM) or saphenous vein graft to the distal right coronary artery. Harvesting of the vein is reported separately since it is obtained from a different procedure site (reference ICD-10-PCS Official Guidelines for Coding and Reporting B3.9). 

Device character A- Autologous Arterial Tissue requires harvesting of an artery. The most common site for arterial harvest is the radial artery. The right internal mammary artery may also be harvested. Please note that it is extremely rare for the left internal mammary artery (LIMA) to be harvested. The LIMA is frequently used to bypass a coronary artery; however, it is almost exclusively used as a pedicle or skeletonized graft, meaning that one end is left in-situ, and the other end is anastomosed directly to a coronary artery.

Device character Z — No Device is assigned when the vessel being used as the bypass material is left in-situ. This character may be reported when either the left or right internal mammary artery is used, however, the left is most common. Terms include "left internal mammary artery freed," "LIMA taken down," or "LIMA to LAD." The correct code for LIMA to LAD is 02100Z9, as there is no device; the LIMA remains in-situ and is sutured to the LAD. The correct code assignment for LIMA to LAD is 02100Z9 because there is no device, instead the LIMA is left in-situ and sutured to the LAD below the occluded area. 

Qualifier character definitions and explanations 

Qualifer character 8 — Internal Mammary Artery, Right is used when the vessel is left in-situ with one end anastomosed directly to a coronary artery. An example of this documentation is Right Internal Mammary Artery (RIMA) to the distal Posterior Descending Artery (PDA). 02100Z8 would be reported for these examples. You will need to read the operative note carefully to determine if the right internal mammary was left in-situ or if it was detached at both ends, with one end sewn to a coronary artery and the other attached to either the aorta or the left internal mammary artery. 

Qualifier character 9 — Internal Mammary Artery, Left is used when the vessel is left in-situ and anastomosed to a coronary artery. This character is also used when an arterial graft (often the RIMA) is sewn from the LIMA to a coronary artery. Documentation would be something like this: free RIMA y-graft pedicled from LIMA to medial branch of ramus intermedius artery or RIMA as a T-graft off the LIMA. Although less common than a traditional LIMA to LAD, this type of procedure is routinely done and should be reported as 02100A9. Left internal thoracic artery may also be used to describe this vessel. 

Qualifier character W — Aorta is reported when one end of the conduit (either venous or arterial) is sewn to a coronary artery and the other end is anastomosed to the aorta. This is used with device character 9 (autologous venous tissue) and A (autologous arterial tissue). 021009W is reported for CABG X1; SVG to Right Coronary artery (RCA). When using device character 9 or A the qualifier will be W (aorta) in most cases. This means the venous or arterial free graft is sutured to a coronary artery above the blockage and then attached to the aorta. 

Now that you understand the device and qualifier character definitions, you need to pair those with the number of coronary arteries for each combination to report the procedures performed correctly. 

Additional resources that may be helpful include Coding Clinic, Third Quarter, 2014, page 8, First Quarter, 2016, page 27-28 and Fourth Quarter, 2016, page 82-83. This link contains CABG illustrations that you may find helpful. 
 

Teresa Seville, RHIT, CCS, is a development analyst at Solventum.