Recombinant hirudin enhances cardiac output and decreases systemic vascular resistance during reperfusion after cardiopulmonary bypass in a porcine model

Traditional Chinese Medicine for Coronary Heart Disease: Clinical Evidence and Possible Mechanisms

Coronary heart disease (CHD) remains a major cause of mortality with a huge economic burden on healthcare worldwide. Here, we conducted a systematic review to investigate the efficacy and safety of Chinese herbal medicine (CHM) for CHD based on high-quality randomized controlled trials (RCTs) and summarized its possible mechanisms according to animal-based researches. 27 eligible studies were identified in eight database searches from inception to June 2018. The methodological quality was assessed using seven-item checklist recommended by Cochrane Collaboration. All the data were analyzed using Rev-Man 5.3 software. As a result, the score of study quality ranged from 4 to 7 points. Meta-analyses showed CHM can significantly reduce the incidence of myocardial infarction and percutaneous coronary intervention, and cardiovascular mortality (P < 0.05), and increase systolic function of heart, the ST-segment depression, and clinical efficacy (P < 0.05). Adverse events were reported in 11 studies, and CHMs were well tolerated in patients with CHD. In addition, CHM exerted cardioprotection for CHD, possibly altering multiple signal pathways through anti-inflammatory, anti-oxidation, anti-apoptosis, improving the circulation, and regulating energy metabolism. In conclusion, the evidence available from present study revealed that CHMs are beneficial for CHD and are generally safe.

Diannexin reduces no-reflow after reperfusion in rabbits with large ischemic myocardial risk zones

INTRODUCTION AND AIMS

In patients with ST-segment elevation myocardial infarction who receive percutaneous coronary intervention and stenting, a large zone with no-reflow is associated with adverse outcomes. During myocardial ischemia/reperfusion, phosphatidylserine (PS) translocates to the surface of endothelial cells triggering attachment of platelets and leukocytes, thus impairing microvascular blood flow. Diannexin, a recombinant dimer of the endogenous human annexin V protein, binds PS and thus inhibits the adverse effects of PS. It has been shown to attenuate postischemic reperfusion injury in several experimental models. We speculated that Diannexin would reduce no-reflow in the heart after coronary artery occlusion (CAO) and reperfusion. Rabbits received: (1) Diannexin 5 min pre-CAO (diannexin pre ischemia [DPI], 400 μg/kg, n = 17), or (2) Diannexin 5 min pre-coronary reperfusion (diannexin pre reperfusion [DPR], 400 μg/kg, n = 20), or (3) saline (Cont, n = 18), with 30 min CAO and 3 h reperfusion. In a secondary analysis, rabbits were divided into two groups based on the overall average risk zone size of 29% of the left ventricle (LV): small (<29% of LV) and large (>29% of LV).

RESULTS

Overall, risk zones and infarct size, and the no-reflow zone were similar in all groups. In hearts with large risk zones the no-reflow area was significantly smaller in both drug-treated groups (DPI, 22 ± 5% and DPR, 22 ± 3% vs. control 40 ± 3%, P < 0.006), the hemorrhagic areas were significantly smaller, and infarct size was reduced at the P < 0.06 level compared with control. In animals with small risk zones there were no significant differences. Diannexin treatment did not affect hemodynamics or LV function.

CONCLUSION

Diannexin was cardioprotective in rabbits with a severe ischemic insult. This is important, because large infarcts accompanied by no-reflow in humans are associated with increased complications. In animals with small risk zones, no significant drug effect was observed.

Antithrombin reduces pulmonary hypertension during reperfusion after cardiopulmonary bypass in a pig

BACKGROUND

Antithrombin (AT) may alleviate many cardiopulmonary bypass (CPB) and ischemia-reperfusion (I/R)-related adverse effects. Using a porcine model of clinical cardiac surgery on CPB, we tested the effects of supplementary AT on myocardial and lung I/R injury.

METHODS

Twenty pigs undergoing 60-min aortic clamping and 75-min normothermic perfusion were randomized in a blinded setting to receive an intravenous (i.v.) bolus of AT (250 IU/kg) (AT group, n = 10) or placebo (n = 10) 15 min before aortic declamping. An additional group of five animals received 500 IU/kg AT in an open-label setting (AT+). Thrombin-antithrombin complexes (TAT), activated clotting times (ACT), AT and myeloperoxidase (MPO) activities, troponin T, and several hemodynamic parameters were measured before CPB and after weaning from CPB up to 120 min after aortic declamping. After 120 min of reperfusion, myocardial and lung biopsies were taken for histological examination.

RESULTS

AT effectively inhibited coagulation as assessed by ACT. In the AT and AT+ groups only, cardiac output (CO) and stroke volume (SV) showed a trend of post-ischemic recovery during the first 15 min after CPB. AT-attenuated reperfusion induced an increase in pulmonary arterial diastolic pressure (PAPD) but did not have significant effects on systemic or pulmonary vascular resistance. The effects of AT on SV, CO, and PAPD were fortified in the AT+ group. AT did not show effects on inflammatory changes in either myocardial or pulmonary tissue specimens. AT did not reduce post-ischemic troponin T release.

CONCLUSION

Supplementary AT, in doses with significant anticoagulant effect, did not alleviate myocardial I/R injury in terms of histological inflammatory changes or post-ischemic troponin T release. Instead, however, AT-attenuated reperfusion induced an increase in pulmonary pressure after CPB. Mechanisms and clinical implications of these effects remain to be explored.

Thrombin generation during reperfusion after coronary artery bypass surgery associates with postoperative myocardial damage

BACKGROUND

Cardiopulmonary bypass and coronary artery bypass grafting (CABG) result in significant thrombin generation and activation of fibrinolysis. Thrombin contributes to myocardial ischemia-reperfusion injury in animal studies, but the role of thrombin in myocardial damage after CABG is unknown.

OBJECTIVES

We measured thrombin generation and fibrin turnover during reperfusion after CABG to evaluate their associations with postoperative hemodynamic changes and myocardial damage.

METHODS

One hundred patients undergoing primary, elective, on-pump CABG were prospectively enrolled. Plasma prothrombin fragment F(1+2) and D-dimer were measured preoperatively and at seven time points thereafter. Mass of the Mb fraction of creatine kinase (Ck-Mbm) and troponin T (TnT) were measured on the first postoperative day.

RESULTS

Reperfusion induced an escalation of thrombin generation and fibrin turnover despite full heparinization. F(1+2) during early reperfusion associated with postoperative pulmonary vascular resistance index. F(1+2) at 6 h after protamine administration correlated with Ck-Mbm (r = 0.40, P < 0.001) and TnT (r = 0.44, P < 0.001) at 18 h postoperatively. Patients with evidence of myocardial damage (highest quintiles of plasma Ck-Mbm and TnT) had significantly higher F(1+2) during reperfusion than others (P < 0.002). Logistic regression models identified F(1+2) during reperfusion to independently associate with postoperative myocardial damage (odds ratios 2.5-4.4, 95% confidence intervals 1.04-15.7).

CONCLUSIONS

Reperfusion caused a burst in thrombin generation and fibrin turnover despite generous heparinization. Thrombin generation during reperfusion after CABG associated with pulmonary vascular resistance and postoperative myocardial damage.

Inhibition of thrombin during reperfusion improves immediate postischemic myocardial function and modulates apoptosis in a porcine model of cardiopulmonary bypass

OBJECTIVE

Transient left-ventricular dysfunction because of myocardial reperfusion injury is a significant problem after cardiac surgery, but the underlying complex pathophysiology is still poorly understood. The authors studied early functional recovery of the postischemic myocardium and explored potential effects of thrombin inhibition on procoagulatory, proinflammatory, and proapoptotic features of myocardial ischemia-reperfusion injury.

DESIGN

A randomized, blinded study.

SETTING

University research laboratory.

SUBJECTS

Porcine model.

INTERVENTIONS

Twenty pigs undergoing 60 minutes of aortic clamping and 75 minutes of normothermic cardiopulmonary bypass (CPB) received an intravenous bolus of r-hirudin (10 mg, 0.4mg/kg, n = 10) or placebo (n = 10) 15 minutes before aortic declamping, followed by a 135-minute intravenous infusion of r-hirudin (3.75 mg, 0.15 mg/kg/h) or placebo.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic parameters were measured before CPB, after weaning from CPB, and at 30, 60, 90, and 120 minutes after aortic declamping. Blood was sampled, and myocardial biopsies were taken before CPB, just before aortic declamping, during reperfusion, and after 120 minutes of reperfusion to measure thrombin antithrombin complexes and to quantitate leukocyte infiltration (myeloperoxidase activity) for histologic evaluation and detection of apoptosis with caspase-3 and the TUNEL method. The r-hirudin group showed significantly higher stroke volume and cardiac output than the control group at 60 minutes and at 90 minutes after aortic declamping (p < 0.05). Microthrombosis was not observed in either group, indicating sufficient anticoagulation and excluding intravascular clots as explanations for LV dysfunction in the current experiment. Instead, ample myocardial activation of inflammation was present, but only a trend of r-hirudin-associated anti-inflammatory effect was observed. Compared with the controls, TUNEL-positive myocytes were detected significantly less frequently in the r-hirudin group (0.05 +/- 0.06 v 0.13 +/- 0.07 TUNEL-positive nuclei %, p = 0.042).

CONCLUSIONS

The improved cardiac recovery in the r-hirudin group during reperfusion after cardioplegia-induced cardiac arrest was associated with significant differences in cardiomyocyte apoptosis and anti-inflammatory effects. Thus, in clinical cardiac surgery, inhibition of reperfusion- induced thrombin may offer beneficial effects by mechanisms other than direct anticoagulation.

Differential Effect of Heparin Coating and Complement Inhibition on Artificial Surface-Induced Eicosanoid Production

BACKGROUND

Contact between blood and artificial surfaces induces an inflammatory response including activation of leukocytes and platelets, as well as complement and other plasma cascade systems. In the present study we investigated the roles of complement and surface modification in polyvinyl chloride-induced synthesis of eicosanoids (arachidonic acid metabolites).

METHODS

Human whole blood was incubated in rotating loops of polyvinyl chloride or heparin-coated polyvinyl chloride tubing for 4 hours. Plasma concentrations of the eicosanoids leukotriene B4, prostaglandin E2 and thromboxane B2 were quantified.

RESULTS

Polyvinyl chloride induced a substantial increase in leukotriene B4, prostaglandin E2, and thromboxane B2. Inhibition of complement activation by the complement factor 3 binding peptide compstatin or blockade of the complement factor 5a receptor with a specific antagonist significantly and specifically inhibited the synthesis of leukotriene B4, whereas thromboxane B2 and prostaglandin E2 synthesis were apparently complement independent. The increase in all three mediators was significantly reduced by the heparin coating. Indomethacin abolished the increase of the cyclooxygenase products prostaglandin E2 and thromboxane B2, but had no effect on the increase of the lipoxygenase product leukotriene B4, consistent with the specificity of indomethacin for the cyclooxygenase and confirming the specificity of complement inhibition.

CONCLUSIONS

Polyvinyl chloride-induced increase in all three eicosanoids was attenuated by heparin coating, whereas complement inhibition selectively reduced the synthesis of leukotriene B4.