Does lung ischemia and reperfusion have an impact on coronary flow? A quantitative coronary blood-flow analysis with inflammatory cytokine profile.

OBJECTIVE: Ischemia-reperfusion (IR) injury remains a major cause of early morbidity and mortality after lung transplantation with poorly documented extrapulmonary repercussions. To determine the hemodynamic effect due to lung IR injury, we performed a quantitative coronary blood-flow analysis in a swine model of in situ lung ischemia and reperfusion. METHODS: In 14 healthy pigs, blood flow was measured in the ascending aorta, left anterior descending (LAD), circumflex (Cx), right coronary artery (RCA), right common carotid artery (RCCA), and left internal mammary artery (LIMA), along with left-and right-ventricular pressures (LVP and RVP), aortic pressure (AoP), and pulmonary artery pressure (PAP). Cardiac Troponin (cTn), interleukin 6 and 10 (IL-6 and IL-10), and tumor necrosis factor A (TNF-A) were measured in coronary sinus blood samples. The experimental (IR) group (n=10) underwent 60 min of lung ischemia followed by 60 min of reperfusion by clamping and releasing the left pulmonary hilum. Simultaneous measurements of all parameters were made at baseline and during IR. The control group (n=4) had similar measurements without lung IR. RESULTS: In the IR group, total coronary flow (TCF=LAD+Cx+RCA blood-flow) decreased precipitously and significantly from baseline (113±41 ml min"1) during IR (p<0.05), with the lowest value observed at 60 min of reperfusion (-37.1%, p<0.003). Baseline cTn (0.08±0.02 ng ml(-1)) increased during IR and peaked at 45 min of reperfusion (+138%, p<0.001). Baseline IL-6 (9.2±2.17 pg ml(-1)) increased during IR and peaked at 60 min of reperfusion (+228%, p<0.0001). Significant LVP drop at 5 min of ischemia (p<0.05) was followed by a slow return to baseline at 45 min of ischemia. A second LVP drop occurred at reperfusion (p<0.05) and persisted. Conversely, RVP increased throughout ischemia (p<0.05) and returned toward baseline during reperfusion. Coronary blood flow and hemodynamic profile remained unchanged in the control group. IL-10 and TNF-A remained below the measurable range for both the groups. CONCLUSIONS: In situ lung IR has a marked negative impact on coronary blood flow, hemodynamics, and inflammatory profile. In addition, to the best of our knowledge, this is the first study where coronary blood flow is directly measured during lung IR, revealing the associated increased cardiac risk.

Effect of dobutamine combined with intra-aortic balloon counterpulsation on left ventricular function early after acute myocardial infarction: experimental study.

Acute myocardial infarction (AMI) causes left ventricular (LV) remodeling, which forms the substrate for its early and late complications. The purpose of this study was to compare the acute effect of dobutamine or intra-aortic balloon pumping (IABP), alone or in combination, on LV function in the early phase of an experimental AMI. In 18 pigs, AMI was induced by ligation of the left anterior descending artery (LAD). IABP or dobutamine infusion at a rate of 5 µg/kg/min, or a combination of the two, was applied immediately after ligation of the LAD. Echocardiographic measurements of the long and short LV axes were obtained before (baseline) and post LAD ligation and at the end of each intervention for 5, 15, and 30 min. The fractional shortening (FS) of both axes, as well as the ejection fraction (EF), was calculated. The combination of dobutamine with IABP increased the EF significantly after the AMI in comparison to dobutamine or IABP alone, and improved the stroke volume, cardiac output, and long axis FS in comparison to IABP alone. Dobutamine alone produced a significantly higher increase of EF in comparison to IABP alone. These results indicate that the combination of dobutamine with IABP may be useful during AMI.