Influence of Lactation on Internal Mammary Artery Size and Flow

Abstract

This prospective study compared internal mammary artery blood flow and diameter and hospital mortality after coronary artery bypass grafting in 3 groups of patients: group 1, 32 women who had breast fed; group 2, 21 women who had not breast fed; and group 3, 30 average-sized males. Mean internal mammary artery flow was significantly lower in group 2 (94 mL·min−1 in group 1, 65 mL·min−1 in group 2, 105 mL·min−1 in group 3). Mean distal internal mammary artery diameter was also less in group 2 (1.35 mm in group 1, 1 mm in group 2, 1.5 mm in group 3). Postoperative myocardial infarction occurred in 1 patient in group 1, 4 in group 2, and 1 in group 3. Anterior myocardial infarction in the 4 patients in group 2 was caused by internal mammary artery spasm. Hospital mortality was 3.13% in group 1, 9.52% in group 2, and 3.33% in group 3. The angina-free period in group 1 was significantly longer than in group 2 (4.5 versus 1.7 years). It was concluded that in women who had not breast fed, the internal mammary artery diameter was inadequate to supply myocardial demand and the graft was prone to lifethreatening spasm.