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

Abstract

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.

Figure 1

The total blood flow changes using coronary electromagnetic flow meter probes in normal and ischaemic myocardium before and during application of −50 mmHg. The measurements were performed at the proximal part of the right coronary artery, the left anterior descending artery and the circumflex coronary artery in six pigs. The change in total coronary artery blood flow is shown as mean values ± standard error of the mean. Statistical analysis was performed using Student’s paired t‐test, and significance was defined as *P < 0·05 and not significant (n.s.) at P > 0·05.

Figure 2

The blood flow measured using coronary electromagnetic flow meter probes in normal myocardium. The measurements were performed at the proximal part of the right coronary artery (RCA), left anterior descending artery (LAD) and circumflex coronary artery (CCX) in the myocardium in six pigs, with a topical negative pressure of −50 mmHg. The results are shown as mean values ± standard error of the mean. Statistical analysis was performed using Student’s paired t‐test, and significance was defined as *P < 0·05 and not significant (n.s.) at P > 0·05. occl, occlusion.

Figure 3

The blood flow measured using coronary electromagnetic flow meter probes before and after 20 minutes of left anterior descending artery (LAD) occlusion. The measurements were performed at the proximal part of the right coronary artery (RCA), LAD and circumflex coronary artery (CCX) in six pigs. Results are shown as mean values ± standard error of the mean. Statistical analysis was performed using Student’s paired t‐test, and significance was defined as *P < 0·05 and not significant (n.s.) at P > 0·05.

Figure 4

The blood flow measured using coronary electromagnetic flow meter probes in ischaemic myocardium. The measurements were performed at the proximal part of the right coronary artery (RCA), the left anterior descending artery (LAD) and the circumflex coronary artery (CCX) in the myocardium in six pigs, with a topical negative pressure of −50 mmHg. The results are shown as mean values ± standard error of the mean. Statistical analysis was performed using Student’s paired t‐test, and significance was defined as *P < 0·05 and not significant (n.s.) at P > 0·05.