Reactive hyperemia in the nonused internal mammary artery after median sternotomy

Doppler spectrum analysis was performed in the nonused internal mammary artery in a group of patients who underwent myocardial revascularization using the contralateral internal mammary artery and in both internal mammary arteries in a group of patients who underwent median sternotomy for cardiac surgical procedures in which the internal mammary artery was not used. In all nonused internal mammary arteries the preoperatively triphasic systolic flow pattern had postoperatively converted into a unidirectional systolic flow pattern with a large diastolic flow component, characterized by a significant increase in the diastolic flow parameters and a significant decrease in the resistance and pulsatility indices. This effect had almost subsided at 6 months postoperatively. This study indicates that the reactive hyperemia observed in the nonused internal mammary artery in the early postoperative period is mainly caused by the temporarily increased metabolic demand of the anterior thoracic wall and mediastinum, rather than by the metabolic demand of the anterior diaphragm and the contralateral rectus abdominis muscle after deprivation of their main nutritional vessel.