Is phrenic nerve dysfunction after cardiac surgery related to internal mammary harvesting?

Although many surgeons feel that internal mammary artery (IMA) harvesting is a risk factor for phrenic nerve dysfunction (PND) following coronary artery bypass grafting surgery (CABG), objective data confirming this are lacking. We sought to compare two groups of cardiac surgical patients to determine if an association exists between IMA harvesting and PND following CABG.

Using inpatient medical records and chest radiographs, we performed a retrospective analysis of 25 consecutive CABG patients and 25 consecutive valve procedure patients in order to compare the incidence of PND following cardiac surgery with and without IMA harvesting.

Two patients were excluded. Thirty-one patients underwent IMA harvesting as part of their procedure, of whom 42% had PND evidenced on postextubation chest X-ray. Seventeen patients did not have IMA harvesting, and the incidence of PND in this group was 12% (p = 0.05). Both groups were similar in preoperative variables and operative techniques.

This study suggests IMA harvesting is indeed a risk factor for PND following CABG.