Effect of vacuum-assisted closure on blood flow in the peristernal thoracic wall after internal mammary artery harvesting

Abstract

Vacuum-assisted closure (VAC) is a recently introduced method for the treatment of poststernotomy mediastinitis. The aim was to examine the effects of VAC negative pressure on peristernal soft tissue blood flow after internal mammary artery harvesting. Microvascular blood flow was measured using laser Doppler velocimetry in a porcine sternotomy wound model. The effect of VAC negative pressure on blood flow to the wound edge was investigated on the right side, where the internal mammary artery was intact, and on the left side, where the internal mammary artery had been removed. Before removal of the left internal mammary artery, the blood flow was similar in the right and left peristernal wound edges, 2.5 cm from the edge (27+/-4 perfusion units (PU) on the right side and 32+/-3 PU on the left side, in muscle tissue). When the left internal mammary artery was surgically removed, the blood flow on the left side decreased (19+/-3 PU, in muscle tissue), while the skin blood flow was not affected. VAC negative pressure induced an immediate increase in wound edge blood flow both on the right side (43+/-9 PU, in muscle tissue at -75 mmHg), where the internal mammary artery was intact, and on the left side, where the internal mammary artery had been removed (49+/-11 PU, in muscle tissue at -75 mmHg). The increase in blood flow was similar on both sides at -75 mmHg and at -125 mmHg. The peristernal wound edge microvascular blood flow is decreased when the left internal mammary artery is removed. VAC therapy stimulates blood flow in the peristernal thoracic wall after internal mammary artery harvesting.