PCI in the left internal mammary artery

Percutaneous coronary intervention in the left internal mammary artery poses several challenges for the interventional cardiologist. A short guide catheter must be used because the distance to the lesion may be quite long, and all efforts must be made to preserve the workable length of the balloon. There is often poor guide catheter support to engage the internal mammary artery. Finally, the internal mammary artery is susceptible to spasm confusing the the diagnosis and treatment of the disease.

The left internal mammary artery can develop disease at 4 separate sites:

1. At the ostium. This should not be confused for spasm. The ostium of the IMA is prone to spasm and aggressive therapy with nitrates is recommended to minimize the possibility that the lesion is due to spasm rather than fixed obstructive disease.
2. At the site of a kink in the IMA.
3. In the body of the IMA (somewhat rare)
4. At the anastomosis of the IMA with the LAD
5. An intervention is sometimes performed in the native LAD distal to the anastomosis

• A short guiding catheter should be used (a 100 cm guide). Otherwise the balloon will not reach distal parts of the left internal mammary artery.
• Coronary spasm may develop at the ostium during the procedure which can be confused with a dissection. Nitrates and repositioning of the wire to minimize wire bias should be performed before stenting the ostium.
• The approach to kinks in an artery such as the IMA is discussed elsewhere.

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