Shufu Chang

TNF-α-induced cardiomyocyte apoptosis contributes to cardiac dysfunction after coronary microembolization in mini-pigs.

This experimental study was designed to clarify the relationship between cardiomyocyte apoptosis and tumour necrosis factor‐alpha (TNF‐α) expression, and confirm the effect of TNF‐α on cardiac dysfunction after coronary microembolization (CME) in mini‐pigs. Nineteen mini‐pigs were divided into three groups: sham‐operation group (n = 5), CME group (n = 7) and adalimumab pre‐treatment group (n = 7; TNF‐α antibody, 2 mg/kg intracoronary injection before CME). Magnetic resonance imaging (3.0‐T) was performed at baseline, 6th hour and 1 week after procedure. Cardiomyocyte apoptosis was detected by cardiac‐TUNEL staining, and caspase‐3 and caspase‐8 were detected by RT‐PCR and immunohistochemistry. Furthermore, serum TNF‐α, IL‐6 and troponin T were analysed, while myocardial expressions of TNF‐α and IL‐6 were detected. Both TNF‐α expression (serum level and myocardial expression) and average number of apoptotic cardiomyocyte nuclei were significantly increased in CME group compared with the sham‐operation group. Six hours after CME, left ventricular end‐systolic volume (LVESV) was increased and the left ventricular ejection fraction (LVEF) was decreased in CME group. Pre‐treatment with adalimumab not only significantly improved LVEF after CME (6th hour: 54.9 ± 2.3% versus 50.4 ± 3.9%, P = 0.036; 1 week: 56.7 ± 4.2% versus 52.7 ± 2.9%, P = 0.041), but also suppressed cardiomyocyte apoptosis and the expression of caspase‐3 and caspase‐8. Meanwhile, the average number of apoptotic cardiomyocytes nuclei was inversely correlated with LVEF (r = −0.535, P = 0.022). TNF‐α‐induced cardiomyocyte apoptosis is likely involved in cardiac dysfunction after CME. TNF‐α antibody therapy suppresses cardiomyocyte apoptosis and improves early cardiac function after CME.

Changes in left ventricular ejection fraction and coronary flow reserve after coronary microembolization

Introduction Although coronary microembolization (CME) is a frequent phenomenon in patients undergoing percutaneous coronary intervention, few data are available on the changes in left ventricular ejection fraction (LVEF) and coronary flow reserve (CFR) after CME. Material and methods In this study, six miniature swine of either sex (body weight 21-25 kg) were used to prepare a CME model. After coronary angiography, 1.2 × 105 microspheres (42 µm) were selectively infused into the left anterior descending artery via an infusion catheter. Left ventricular ejection fraction was evaluated using transthoracic echocardiography; myocardial blood flow was measured using coloured microspheres; and CFR and coronary pressure were measured using Doppler and a pressure wire. Results Left ventricular ejection fraction was 0.77 ±0.08 at baseline, 0.69 ±0.08 at 2 h, 0.68 ±0.08 at 6 h, and 0.76 ±0.06 at 1 week (2 h vs. baseline p < 0.05; 6 h vs. baseline p < 0.01). After CME, left ventricular end systolic volume (LVESV) and end diastolic volume (LVEDV) were significant larger 1 week later (p < 0.01 for both), while CFR was significantly reduced at 6 h (1.24 ±0.10 at 6 h vs. 1.77 ±0.30 at baseline, p < 0.01) and myocardial blood flow remained unchanged. Serum ET-1 level was significantly higher only at 6 h after CME (6 h vs. baseline p < 0.05). Conclusions Reduction of CFR and LVEF is significant at 6 h after CME and recovers 1 week later with left ventricular dilation.

Glucocorticoid ameliorates early cardiac dysfunction after coronary microembolization and suppresses TGF-β1/Smad3 and CTGF expression

OBJECTIVES This study was designed to evidence the protective effect of glucocorticoid therapy on cardiac dysfunction after coronary microembolization (CME), and to clarify its mechanism with the expression of transforming growth factor-beta 1 (TGF-β1)/Smad3 and connective tissue growth factor (CTGF). METHODS Eighteen mini-pigs were studied, including Sham-operation group (n=4), CME group (n=8) and Glucocorticoid therapy group (n=6, received methylprednisolone 25mg/kg intravenously 30 min before CME). Magnetic resonance imaging (3.0-T) was performed at baseline, 6th hour and one week after operation to evaluate cardiac function. Serum TGF-β1, CTGF and troponin T were also detected. Myocardial expressions of TGF-β1, CTGF and Smad3 were detected by western blot and immunohistochemistry. Total collagen expression was demonstrated by Masson Trichrome stain. RESULTS Compared with Sham-operation group, left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) in CME group were increased at 6th hour after CME, while left ventricular ejection fraction (LVEF) was decreased significantly. Compared with CME group, methylprednisolone greatly improved LVEF after CME (6th hour: 56.0 ± 3.2% vs. 51.8 ± 3.8%, P=0.030; one week: 57.8 ± 3.2% vs. 54.6 ± 2.6%, P=0.053). We found that methylprednisolone not only significantly decreased serum TGF-β1, CTGF and troponin T, but also reduced myocardial expressions of TGF-β1, CTGF and Smad3 after CME. In addition, collagen volume fraction in glucocorticoid therapy group was markedly lower than that in CME group. CONCLUSIONS Glucocorticoid therapy could improve early cardiac function after CME, and its mechanism could be associated with TGF-β1/Smad3 and CTGF suppression.

Exenatide Reduces Tumor Necrosis Factor-α-induced Apoptosis in Cardiomyocytes by Alleviating Mitochondrial Dysfunction.

Background:Tumor necrosis factor-&agr; (TNF-&agr;) plays an important role in progressive contractile dysfunction in several cardiac diseases. The cytotoxic effects of TNF-&agr; are suggested to be partly mediated by reactive oxygen species (ROS)- and mitochondria-dependent apoptosis. Glucagon-like peptide-1 (GLP-1) or its analogue exhibits protective effects on the cardiovascular system. The objective of the study was to assess the effects of exenatide, a GLP-1 analogue, on oxidative stress, and apoptosis in TNF-&agr;-treated cardiomyocytes in vitro. Methods:Isolated neonatal rat cardiomyocytes were divided into three groups: Control group, with cells cultured in normal conditions without intervention; TNF-&agr; group, with cells incubated with TNF-&agr; (40 ng/ml) for 6, 12, or 24 h without pretreatment with exenatide; and exenatide group, with cells pretreated with exenatide (100 nmol/L) 30 mins before TNF-&agr; (40 ng/ml) stimulation. We evaluated apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and flow cytometry, measured ROS production and mitochondrial membrane potential (MMP) by specific the fluorescent probes, and assessed the levels of proteins by Western blotting for all the groups. Results:Exenatide pretreatment significantly reduced cardiomyocyte apoptosis as measured by flow cytometry and TUNEL assay at 12 h and 24 h. Also, exenatide inhibited excessive ROS production and maintained MMP. Furthermore, declined cytochrome-c release and cleaved caspase-3 expression and increased bcl-2 expression with concomitantly decreased Bax activation were observed in exenatide-pretreated cultures. Conclusion:These results suggested that exenatide exerts a protective effect on cardiomyocytes, preventing TNF-&agr;-induced apoptosis; the anti-apoptotic effects may be associated with protection of mitochondrial function.

Impact of Neutrophil to Lymphocyte Ratio (NLR) Index and Its Periprocedural Change (NLRΔ) for Percutaneous Coronary Intervention in Patients With Chronic Total Occlusion.

We assessed the association between neutrophil to lymphocyte ratio (NLR) and chronic coronary total occlusion (CTO), as well as clinical prognosis of percutaneous coronary intervention (PCI). Patients referred for elective coronary angiography for stable angina pectoris were enrolled, including a CTO (n = 160) and a non-CTO group (n = 160). Neutrophil to lymphocyte ratio on admission and post-PCI was measured, and NLRΔ was defined as the change between the 2 values. Subgroup analysis was performed based on the value of NLRΔ (≥0.5 vs <0.5). Clinical characteristics, angiographic data, and follow-up data were recorded. Compared with the non-CTO group, the total white blood cell count, neutrophil counts, and NLR were significantly higher in the CTO group. In the NLRΔ ≥ 0.5 subgroup, the incidence of severe dissection, slow coronary flow, in-stent restenosis (ISR), and major adverse cardiac events (MACEs) was obviously higher. In multivariate analysis, NLRΔ was independently and positively associated with higher risks of ISR and MACE. The NLR could be a potential predictor of CTO, and NLRΔ is independently associated with the adverse clinical outcomes in patients who underwent PCI.

Evaluation of Preprocedural Laboratory Parameters as Predictors of Drug-Eluting Stent Restenosis in Coronary Chronic Total Occlusion Lesions

This retrospective, single-center study assessed the prognostic value of several emerging inflammatory markers as predictors of in-stent restenosis (ISR) after drug-eluting stent implantation for coronary chronic total occlusion (CTO) lesions. Consecutive patients (n = 416) who underwent successful percutaneous coronary intervention (PCI) for documented CTO lesions and with follow-up angiography were enrolled. Preprocedural high-sensitivity C-reactive protein (hsCRP), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and red cell distribution width (RDW) were analyzed. At mean follow-up of 14.4 ± 3.3 months, ISR occurred in 72 patients. Compared with the non-ISR group, preprocedural hsCRP level, PLR, NLR, and RDW were significantly higher in the ISR group. The ISR group also had significantly greater proportions of patients with diabetes and smoking history, lower estimated glomerular filtration rate, higher low-density lipoprotein cholesterol (LDL-C) level and neutrophil count, longer stent length, and higher rate of severe dissection. In multivariate analysis, NLR (odds ratio [OR]: 3.110; 95% confidence interval [CI], 2.102-4.063; P < .001) and PLR (OR: 1.029; 95% CI, 1.016-1.143; P < .001) were independent predictors of ISR, along with LDL-C level and stent length. In conclusion, higher preprocedural NLR and PLR levels were independent risk factors for the development of ISR in patients who underwent PCI for CTO lesions.

Coronary Microembolization with Normal Epicardial Coronary Arteries and No Visible Infarcts on Nitrobluetetrazolium Chloride-Stained Specimens: Evaluation with Cardiac Magnetic Resonance Imaging in a Swine Model.

Objective To assess magnetic resonance imaging (MRI) features of coronary microembolization in a swine model induced by small-sized microemboli, which may cause microinfarcts invisible to the naked eye. Materials and Methods Eleven pigs underwent intracoronary injection of small-sized microspheres (42 µm) and catheter coronary angiography was obtained before and after microembolization. Cardiac MRI and measurement of cardiac troponin T (cTnT) were performed at baseline, 6 hours, and 1 week after microembolization. Postmortem evaluation was performed after completion of the imaging studies. Results Coronary angiography pre- and post-microembolization revealed normal epicardial coronary arteries. Systolic wall thickening of the microembolized regions decreased significantly from 42.6 ± 2.0% at baseline to 20.3 ± 2.3% at 6 hours and 31.5 ± 2.1% at 1 week after coronary microembolization (p < 0.001 for both). First-pass perfusion defect was visualized at 6 hours but the extent was largely decreased at 1 week. Delayed contrast enhancement MRI (DE-MRI) demonstrated hyperenhancement within the target area at 6 hours but not at 1 week. The microinfarcts on gross specimen stained with nitrobluetetrazolium chloride were invisible to the naked eye and only detectable microscopically. Increased cTnT was observed at 6 hours and 1 week after microembolization. Conclusion Coronary microembolization induced by a certain load of small-sized microemboli may result in microinfarcts invisible to the naked eye with normal epicardial coronary arteries. MRI features of myocardial impairment secondary to such microembolization include the decline in left ventricular function and myocardial perfusion at cine and first-pass perfusion imaging, and transient hyperenhancement at DE-MRI.

Assessment of the acute effects of glucocorticoid treatment on coronary microembolization using cine, first-pass perfusion, and delayed enhancement MRI

To assess the acute effects of methylprednisone treatment (MPT) on coronary microembolization (CME) by cardiac cine, first‐pass perfusion, and delayed gadolinium enhancement magnetic resonance imaging (DE‐MRI) in an experimental swine model.

Establishment of a Novel Mouse Model of Coronary Microembolization

Background:Coronary microembolization (CME) has been frequently seen in acute coronary syndromes and percutaneous coronary intervention. Small animal models are required for further studies of CME related to severe prognosis. This study aimed to explore a new mouse model of CME. Methods:The mouse model of CME was established by injecting polystyrene microspheres into the left ventricular chamber during 15-s occlusion of the ascending aorta. Based on the average diameter and dosage used, 30 C57BL/6 male mice were randomly divided into five groups (n = 6 in each): 9 &mgr;m/500,000, 9 &mgr;m/800,000, 17 &mgr;m/200,000, 17 &mgr;m/500,000, and sham groups. The postoperative survival and performance of the mice were recorded. The mice were sacrificed 3 or 10 days after the surgery. The heart tissues were harvested for hematoxylin and eosin staining and Masson trichrome staining to compare the extent of inflammatory cellular infiltration and fibrin deposition among groups and for scanning transmission electron microscopic examinations to see the ultrastructural changes after CME. Results:Survival analysis demonstrated that the cumulative survival rate of the 17 &mgr;m/500,000 group was significantly lower than that of the sham group (0/6 vs. 6/6, P = 0.001). The cumulative survival rate of the 17 &mgr;m/200,000 group was lower than those of the sham and 9 &mgr;m groups with no statistical difference (cumulative survival rate of the 17 &mgr;m/200,000, 9 &mgr;m/800,000, 9 &mgr;m/500,000, and sham groups was 4/6, 5/6, 6/6, and 6/6, respectively). The pathological alterations were similar between the 9 &mgr;m/500,000 and 9 &mgr;m/800,000 groups. The extent of inflammatory cellular infiltration and fibrin deposition was more severe in the 17 &mgr;m/200,000 group than in the 9 &mgr;m/500,000 and 9 &mgr;m/800,000 groups 3 and 10 days after the surgery. Scanning transmission electron microscopic examinations revealed platelet aggregation and adhesion, microthrombi formation, and changes in cardiomyocytes. Conclusion:The injection of 500,000 polystyrene microspheres at an average diameter of 9 &mgr;m is proved to be appropriate for the mouse model of CME based on the general conditions, postoperative survival rates, and pathological changes.

Exploration of Bivalirudin Use during Percutaneous Coronary Intervention for High Bleeding Risk Patients with Chronic Total Occlusion

The safety and efficacy of bivalirudin during percutaneous coronary intervention (PCI) in high bleeding risk patients with chronic total occlusion lesions (CTO) has not been studied till date. The use of bivalirudin may increase the thrombotic events during CTO-PCI.Between May 2013 and April 2014, a total of 117 high bleeding risk patients with CTOs underwent PCI. Bivalirudin was used in 89 cases with different strategies, including standard usage, combination of heparin, and additional bolus of bivalirudin on the basis of standard usage. The clinical characteristics, procedural details and antithrombotic strategies were assessed, and the bleeding and ischemic events were evaluated. The first 7 of 9 patients with standard application of bivalirudin exhibited acute thrombogenesis in the procedure. Heparin was then added in decreasing amounts in the next 8 patients wherein no thrombosis occurred; however, 2 patients had bleeding complications. The subsequent 72 patients were randomly assigned to the heparin bolus or additional bivalirudin bolus groups before the percutaneous transluminal coronary angioplasty (PTCA) was performed. The baseline clinical characteristics and procedure information were identical in both the groups. There were no ischemic and bleeding events in both the groups during the 6-month follow-up.Monotherapy with bivalirudin in CTO-PCI should be treated with caution, as the potential risk of thrombogenesis may be due to the long procedure time, the frequent change of equipment and temporary blood flow convection. Combination of heparin or an additional bolus of bivalirudin before PTCA was observed to be likely to decrease the incidence of thrombogenesis.