Topical negative pressure effects on coronary blood flow in a sternal wound model

Several studies have suggested that mediastinitis is a strong predictor for poor long-term survival after coronary artery bypass surgery (CABG). In those studies, several conventional wound-healing techniques were used. Previously, we have shown no difference in long-term survival between CABG patients with topical negative pressure (TNP)-treated mediastinitis and CABG patients without mediastinitis. The present study was designed to elucidate if TNP, applied over the myocardium, resulted in an increase of the total amount of coronary blood flow. Six pigs underwent median sternotomy. The coronary blood flow was measured, before and after the application of TNP (-50 mmHg), using coronary electromagnetic flow meter probes. Analyses were performed before left anterior descending artery (LAD) occlusion (normal myocardium) and after 20 minutes of LAD occlusion (ischaemic myocardium). Normal myocardium: 171.3 +/- 14.5 ml/minute before to 206.3 +/- 17.6 ml/minute after TNP application, P < 0.05. Ischaemic myocardium: 133.7 +/- 18.4 ml/minute before to 183.2 +/- 18.9 ml/minute after TNP application, P < 0.05. TNP of -50 mmHg applied over the LAD region induced a significant increase in the total coronary blood flow in both normal and ischaemic myocardium.