Myocardial Ischemia Induces Interleukin-6 and Tissue Factor Production in Patients With Coronary Artery Disease

The association of coronary flow changes and inflammatory indices to ischaemia-reperfusion microvascular damage and left ventricular remodelling

BACKGROUND

The aim of this study was to investigate the effect of coronary flow (CF) changes and inflammatory indices on myocardial microcirculation--assessed by myocardial contrast echocardiography (MCE)--and on left ventricular remodelling, in an experimental ischaemia-reperfusion model.

METHODS

In 15 pigs, weighing 30 +/- 5 kg, ligation of the left anterior descending (LAD) coronary artery was performed, followed by reperfusion for 120 min. Peak, mean, duration and volume of systolic and diastolic components of CF distal to the LAD ligation were measured using a butterfly flowmeter and their ratio was calculated. The following two-dimensional echocardiography indices of LV geometry/function were measured from the apical four-chamber view: LV end-systolic (ESD) and end-diastolic (EDD) dimension long- (Ls, Ld) and short-axis (Ss, Sd) and their ratio (Ld/Sd, Ls/Ss, defined as the sphericity index). Interleukin (IL) 1beta, 6, 10 and tumour necrosis factor (TNF) were measured in samples obtained from the LV cavity and coronary sinus. A 0.5 ml/min injection slow bolus over 30 s of SonoVue was made into the left ventricle (LV) in order to assess myocardial perfusion by MCE. Standard apical four-chamber views were digitally acquired and stored for off-line analysis using the Echofit system. The peak intensity (Ac) of the microbubbles at the apex, distally to ligation, was normalised with respect to the peak intensity of the microbubbles in the LV cavity. All parameters were recorded at baseline, immediately after ligation and at 5, 15, 30, 60, 120 min during reperfusion. The percentage changes of CF indices, echocardiographic parameters, interleukins and Ac between baseline and reperfusion were calculated.

RESULTS

Mean systolic CF, systolic volume, peak and mean diastolic flow (MDF) changes and epicardial mean CF, Ld/Sd, Ls/Ss changes and coronary sinus IL-6 (IL-6 cs) were inversely correlated with Ac changes during reperfusion. At 5 and 15 min of reperfusion (hyperaemic phase), the greatest median increase of mean diastolic (172% and 86%), and mean systolic CF (713% and 344%) and the greatest reduction of Ac (-41% at 5 min) compared to baseline (P < 0.05) were observed. The maximum increase of IL-6 cs (40%) was detected at 120 min. ROC analysis showed that of all examined echocardiography indices an increase of mean diastolic CF > 22% was the best predictor of a >25% reduction of Ac with 76% sensitivity and 65% specificity (area 71%, CI 54%-85%, P = 0.02). In addition an >32% increase of IL-6 at 120 min of reperfusion predicted a >25% reduction of Ac with a 76% sensitivity and 65% specificity (area 71% CI 61%-97%, P = 0.01).

CONCLUSION

Changes of mean diastolic CF and IL-6 cs are associated with alterations in myocardial microvascular integrity after ischaemia-reperfusion and may be used as a predictor of myocardial dysfunction.

Psychobiology of depression/distress in congestive heart failure

Heart failure affects millions of Americans and new diagnosis rates are expected to almost triple over the next 30 years as our population ages. Affective disorders including clinical depression and anxiety are common in patients with congestive heart failure. Furthermore, the presence of these disorders significantly impacts quality of life, medical outcomes, and healthcare service utilization. In recent years, the literature has attempted to describe potential pathophysiologic mechanisms relating affective disorders and psychosocial stress to heart failure. Several potential mechanisms have been proposed including autonomic nervous system dysfunction, inflammation, cardiac arrhythmias, and altered platelet function. These mechanisms are reviewed in this article. Additional novel mechanisms such as mental stress-induced myocardial ischemia are also discussed.

Pharmacogenomics and end-organ susceptibility to injury in the perioperative period

Genomic medicine has provided new mechanistic understanding for many complex diseases over the last 5-10 years. More recently genomic approaches have been applied to the perioperative paradigm, facilitating identification of patients at high risk for adverse events, as well as those who will respond better/worse to specific pharmacologic therapies. The consistent biological theme emerging is that while inflammation is important in healing from surgical trauma, patients who are too robustly proinflammatory appear to be at higher risk for adverse perioperative events. Precise predictors of each adverse event are being elucidated so that corrective therapeutics can be instituted to improve outcomes in high-risk patients. While the field of perioperative genomics could be considered in its infancy, such approaches are the wave of the future.

Inflammatory response and cardioprotection during open-heart surgery: the importance of anaesthetics

Open-heart surgery triggers an inflammatory response that is largely the result of surgical trauma, cardiopulmonary bypass, and organ reperfusion injury (e.g. heart). The heart sustains injury triggered by ischaemia and reperfusion and also as a result of the effects of systemic inflammatory mediators. In addition, the heart itself is a source of inflammatory mediators and reactive oxygen species that are likely to contribute to the impairment of cardiac pump function. Formulating strategies to protect the heart during open heart surgery by attenuating reperfusion injury and systemic inflammatory response is essential to reduce morbidity. Although many anaesthetic drugs have cardioprotective actions, the diversity of the proposed mechanisms for protection (e.g. attenuating Ca(2+) overload, anti-inflammatory and antioxidant effects, pre- and post-conditioning-like protection) may have contributed to the slow adoption of anaesthetics as cardioprotective agents during open heart surgery. Clinical trials have suggested at least some cardioprotective effects of volatile anaesthetics. Whether these benefits are relevant in terms of morbidity and mortality is unclear and needs further investigation. This review describes the main mediators of myocardial injury during open heart surgery, explores available evidence of anaesthetics induced cardioprotection and addresses the efforts made to translate bench work into clinical practice.

The fibrin-derived peptide Bbeta15-42 is cardioprotective in a pig model of myocardial ischemia-reperfusion injury

OBJECTIVE

The fibrin-derived peptide Bbeta15-42 has been shown to reduce infarct size in rodent models of ischemia-reperfusion injury. To increase its potential for translation into the clinic, we studied the effects of Bbeta15-42 in pigs, whose coronary anatomy is similar to that of humans. In addition, we evaluated the pharmacokinetics and safety of Bbeta15-42 in several species, including humans.

DESIGN

Animal study and phase I trial.

SETTING

University hospital and contract research laboratories.

SUBJECTS

Pigs/healthy volunteers.

INTERVENTIONS

Male farm-bred Landrace pigs were subjected to 1 hr of left anterior descending coronary artery occlusion followed by 3 hrs of reperfusion. At the time of reperfusion, Bbeta15-42 (2.4 mg/kg, n = 6) or random peptide (control; 2.4 mg/kg, n = 6) was administered as an intravenous bolus. As a positive control, pigs were subjected to ischemic preconditioning (n = 6). Cardiac damage and hemodynamics were recorded. Biodistribution and pharmacokinetics of Bbeta15-42 were determined in rats and dogs. In a phase I trial involving 30 male healthy volunteers, pharmacokinetics and safety were tested in a randomized, double-blinded, placebo-controlled, parallel-group, single ascending dose study.

MEASUREMENTS AND MAIN RESULTS

Bbeta15-42 and ischemic preconditioning significantly reduced myocardial infarct size and troponin I levels. Bbeta15-42 also reduces interleukin-6 levels, underlining its anti-inflammatory properties. Furthermore, in humans, the pharmacokinetics of the peptide Bbeta15-42 were comparable to those of animals, and no serious adverse effects were observed.

CONCLUSIONS

Bbeta15-42 elicits cardioprotection in pigs and is clinically safe in phase I testing of humans. This study confirms the new concept of a pathogenic role of fibrin derivatives in myocardial reperfusion injury, which can be inhibited by peptide Bbeta15-42.

Matrix metalloproteinase inhibitors as therapy for inflammatory and vascular diseases

Matrix metalloproteinases (MMPs) have outgrown the field of extracellular-matrix biology and have progressed towards being important regulatory molecules in cancer and inflammation. This rise in status was accompanied by the development of various classes of inhibitors. Although clinical trials with synthetic inhibitors for the treatment of cancer were disappointing, recent data indicate that the use of selective inhibitors might lead to new therapies for acute and chronic inflammatory and vascular diseases. In this Review, we compare the major classes of MMP inhibitors and advocate that future drug discovery should be based on crucial insights into the differential roles of specific MMPs in pathophysiology obtained with animal models, including knockout studies.

Long-term pericardial catheterization is associated with minimum foreign-body response

OBJECTIVES

The goals of this study were to assess the feasibility and to characterize the foreign-body response of a long-term catheter in the pericardium.

BACKGROUND

Long-term access to the normal pericardial space provides opportunities for diagnostic sampling and therapeutic intervention.

METHODS

After thoracotomy, in 7 anesthetized canines, the pericardium was opened and a 5 French silicone vascular access catheter was advanced 10 cm into the pericardial sac toward the apex of the heart. A hydraulic coronary balloon occluder was implanted (N=6). Pericardium was sealed with Prolene suture. Catheters were tunneled to the nape of the neck, attached to a subcutaneous vascular access port, and buried in the fascia. Animals underwent multiple experimental coronary artery occlusions across months. At sacrifice, we assessed the histopathological response of pericardium and epicardium to chronically indwelling silicone catheters.

RESULTS

Post-mortem examinations were performed at 213 days post-operatively (mean, range=96-413, N=6), with one animal maintained for longer-term study. At sacrifice, all catheters were bidirectionally patent and completely mobile in the pericardium without evidence of tissue overgrowth around the intrapericardial segment. Adhesion tissue was found only at the site of catheter entry through the pericardium. Microscopic histopathological examination at catheter entry site, surrounding pericardium, and myocardium revealed minimum chronic inflammation.

CONCLUSIONS

This subcutaneous system provides dependable, chronic access to the normal pericardial space for drug delivery and sampling. The presence of a chronic silicone catheter in the pericardium does not precipitate clinically significant pathologic changes even after repeated ischemic events.

Etiology, pathogenesis and management of thoracic aortic aneurysm

Given the growing proportion of elderly people in Western societies and the increasing prevalence of chronic hypertension, the management of aneurysmal aortic disease is an ever growing challenge. Although degenerative changes in the aortic wall are common to thoracic aortic aneurysm (TAA) and to various types of dissection in general, TAA can result from specific heritable disorders of connective tissues. Today, increased awareness of vascular diseases and access to tomographic imaging equipment facilitate the diagnosis of TAA, even when asymptomatic. While most TAA cases with ascending aortic involvement are treated with surgical repair (primarily valve-preserving techniques), aneurysms of the distal arch and descending thoracic aorta are amenable to alternatives to classic open repair such as the emerging endovascular treatment techniques. In this Review, we provide a comprehensive overview of the etiology, pathophysiology and clinical management of patients with TAA, and discuss the most recent literature on the condition.

Pathogenesis of thoracic and abdominal aortic aneurysms

The major disease processes affecting the aorta are aortic aneurysms and dissections. Aneurysms are usually described in terms of their anatomic location, with thoracic aortic aneurysms (TAAs) involving the ascending and descending aorta in the thoracic cavity and abdominal aortic aneurysms (AAAs) involving the infrarenal abdominal aorta. Both thoracic and abdominal aortas are elastic arteries, and share similarities in their physical structures and cellular components. However, thoracic and abdominal aortas differ in their biochemical properties and the origin of their vascular smooth muscle cells (VSMCs). These similarities and differences between thoracic and abdominal aortas provide the basis for the various pathologic mechanisms observed in this disease. This review focuses on the comparison of the pathologic mechanisms involved in TAA and AAA.

Matrix metalloproteinases in development and disease

Matrix metalloproteinases (MMPs) are key modulators of many biological processes during pathophysiological events, such as skeletal formation, angiogenesis, cellular migration, inflammation, wound healing, coagulation, lung and cardiovascular diseases, arthritis, and cancer. Twenty-four members of the MMP family have been identified in humans, degrading many components of the extracellular matrix, cellular receptors, and cytokines. This review describes the molecular structure, activation and inhibition, and substrate specificity of MMPs, and their biological function in development and disease.