The pathophysiology of myocardial ischaemia

Eph-ephrin signaling couples endothelial cell sorting and arterial specification

Cell segregation allows the compartmentalization of cells with similar fates during morphogenesis, which can be enhanced by cell fate plasticity in response to local molecular and biomechanical cues. Endothelial tip cells in the growing retina, which lead vessel sprouts, give rise to arterial endothelial cells and thereby mediate arterial growth. Here, we have combined cell type-specific and inducible mouse genetics, flow experiments in vitro, single-cell RNA sequencing and biochemistry to show that the balance between ephrin-B2 and its receptor EphB4 is critical for arterial specification, cell sorting and arteriovenous patterning. At the molecular level, elevated ephrin-B2 function after loss of EphB4 enhances signaling responses by the Notch pathway, VEGF and the transcription factor Dach1, which is influenced by endothelial shear stress. Our findings reveal how Eph-ephrin interactions integrate cell segregation and arteriovenous specification in the vasculature, which has potential relevance for human vascular malformations caused by EPHB4 mutations.

Pathophysiological mechanisms underlying increased circulating cardiac troponin in noncardiac surgery: a narrative review

Assay-specific increases in circulating cardiac troponin are observed in 20-40% of patients after noncardiac surgery, depending on patient age, type of surgery, and comorbidities. Increased cardiac troponin is consistently associated with excess morbidity and mortality after noncardiac surgery. Despite these findings, the underlying mechanisms are unclear. The majority of interventional trials have been designed on the premise that ischaemic cardiac disease drives elevated perioperative cardiac troponin concentrations. We consider data showing that elevated circulating cardiac troponin after surgery could be a nonspecific marker of cardiomyocyte stress. Elevated concentrations of circulating cardiac troponin could reflect coordinated pathological processes underpinning organ injury that are not necessarily caused by ischaemia. Laboratory studies suggest that matching of coronary artery autoregulation and myocardial perfusion-contraction coupling limit the impact of systemic haemodynamic changes in the myocardium, and that type 2 ischaemia might not be the likeliest explanation for cardiac troponin elevation in noncardiac surgery. The perioperative period triggers multiple pathological mechanisms that might cause cardiac troponin to cross the sarcolemma. A two-hit model involving two or more triggers including systemic inflammation, haemodynamic strain, adrenergic stress, and autonomic dysfunction might exacerbate or initiate acute myocardial injury directly in the absence of cell death. Consideration of these diverse mechanisms is pivotal for the design and interpretation of interventional perioperative trials.

Considerations for choosing an optimal animal model of cardiovascular disease

The decision to use the optimal animal model to mimic the various types of cardiovascular disease is a critical one for a basic scientist. Clinical cardiovascular disease can be complex and presents itself as atherosclerosis, hypertension, ischemia/reperfusion injury, myocardial infarcts, and cardiomyopathies, amongst others. This may be further complicated by the simultaneous presence of two or more cardiovascular lesions (for example, atherosclerosis and hypertension) and co-morbidities (i.e., diabetes, infectious disease, obesity, etc). This variety and merging of disease states creates an unusually difficult situation for the researcher who needs to identify the optimal animal model that is available to best represent all of the characteristics of the clinical cardiovascular disease. The present manuscript reviews the characteristics of the various animal models of cardiovascular disease available today, their advantages and disadvantages, with the goal to allow the reader access to the most recent data available for optimal choices prior to the initiation of the study. The animal species that can be chosen, the methods of generating these models of cardiovascular disease, as well as the specific cardiovascular lesions involved in each of these models are reviewed. A particular focus on the JCR:LA-cp rat as a model of cardiovascular disease is discussed.

Primary versus iatrogenic (post-PCI) coronary microvascular dysfunction: a wire-based multimodal comparison

BACKGROUND

Although there are studies examining each one separately, there are no data in the literature comparing the magnitudes of the iatrogenic, percutaneous coronary intervention (PCI)-induced, microvascular dysfunction (Type-4 CMD) and coronary microvascular dysfunction (CMD) in the setting of ischaemia in non-obstructed coronary arteries (INOCA) (Type-1 CMD).

OBJECTIVES

We aimed to compare the characteristics of Type-1 and Type-4 CMD subtypes using coronary haemodynamic (resistance and flow-related parameters), thermodynamic (wave energy-related parameters) and hyperemic ECG changes.

METHODS

Coronary flow reserve (CFR) value of <2.5 was defined as CMD in both groups. Wire-based multimodal perfusion markers were comparatively analysed in 35 patients (21 INOCA/CMD and 14 CCS/PCI) enrolled in NCT05471739 study.

RESULTS

Both groups had comparably blunted CFR values per definition (2.03±0.22 vs 2.11±0.37; p: 0.518) and similar hyperemic ST shift in intracoronary ECG (0.16±0.09 vs 0.18±0.07 mV; p: 0.537). While the Type-1 CMD was characterised with impaired hyperemic blood flow acceleration (46.52+12.83 vs 68.20+28.63 cm/s; p: 0.017) and attenuated diastolic microvascular decompression wave magnitudes (p=0.042) with higher hyperemic microvascular resistance (p<0.001), Type-4 CMD had blunted CFR mainly due to higher baseline flow velocity due to post-occlusive reactive hyperemia (33.6±13.7 vs 22.24±5.3 cm/s; p=0.003).

CONCLUSIONS

The perturbations in the microvascular milieu seen in CMD in INOCA setting (Type-1 CMD) seem to be more prominent than that of seen following elective PCI (Type-4 CMD), although resulting reversible ischaemia is equally severe in the downstream myocardium.

H2S Donors with Cytoprotective Effects in Models of MI/R Injury and Chemotherapy-Induced Cardiotoxicity

Hydrogen sulfide (H2S) is an endogenous signaling molecule that greatly influences several important (patho)physiological processes related to cardiovascular health and disease, including vasodilation, angiogenesis, inflammation, and cellular redox homeostasis. Consequently, H2S supplementation is an emerging area of interest, especially for the treatment of cardiovascular-related diseases. To fully unlock the medicinal properties of hydrogen sulfide, however, the development and refinement of H2S releasing compounds (or donors) are required to augment its bioavailability and to better mimic its natural enzymatic production. Categorizing donors by the biological stimulus that triggers their H2S release, this review highlights the fundamental chemistry and releasing mechanisms of a range of H2S donors that have exhibited promising protective effects in models of myocardial ischemia-reperfusion (MI/R) injury and cancer chemotherapy-induced cardiotoxicity, specifically. Thus, in addition to serving as important investigative tools that further advance our knowledge and understanding of H2S chemical biology, the compounds highlighted in this review have the potential to serve as vital therapeutic agents for the treatment (or prevention) of various cardiomyopathies.

Coronary Flow Evaluation in Heart Transplant Patients Compared to Healthy Controls Documents the Superiority of Coronary Flow Velocity Reserve Companion as Diagnostic and Prognostic Tool

Background

Distinct contributions by functional or structural alterations of coronary microcirculation in heart transplantation (HT) and their prognostic role have not been fully elucidated. We aimed to identify the mechanisms of coronary microvascular dysfunction (CMD) in HT and their prognostic implications.

Methods

134 patients, surviving at least 5 years after HT, without evidence of angiographic vasculopathy or symptoms/signs of rejection were included. 50 healthy volunteers served as controls. All underwent the assessment of rest and hyperemic coronary diastolic peak flow velocity (DPVr and DPVh) and coronary flow velocity reserve (CFVR) and its inherent companion that is based on the adjusted quadratic mean: CCFVR = √{(DPVr)2 + (DPVh)2}. Additionally, basal and hyperemic coronary microvascular resistance (BMR and HMR) were estimated.

Results

Based on CFVR and DPVh, HT patients can be assigned to four endotypes: endotype 1, discordant with preserved CFVR (3.1 ± 0.4); endotype 2, concordant with preserved CFVR (3.4 ± 0.5); endotype 3, concordant with impaired CFVR (1.8 ± 0.3) and endotype 4, discordant with impaired CFVR (2.0 ± 0.2). Intriguingly, endotype 1 showed lower DPVr (p &lt; 0.0001) and lower DPVh (p &lt; 0.0001) than controls with lower CFVR (p &lt; 0.0001) and lower CCFVR (p &lt; 0.0001) than controls. Moreover, both BMR and HMR were higher in endotype 1 than in controls (p = 0.001 and p &lt; 0.0001, respectively), suggesting structural microvascular remodeling. Conversely, endotype 2 was comparable to controls. A 13/32 (41%) patients in endotype 1 died in a follow up of 28 years and mortality rate was comparable to endotype 3 (14/31, 45%). However, CCFVR was &lt; 80 cm/s in all 13 deaths of endotype 1 (characterized by preserved CFVR). At multivariable analysis, CMD, DPVh &lt; 75 cm/s and CCFVR &lt; 80 cm/s were independent predictors of mortality. The inclusion of CCFVR &lt; 80 cm/s to models with clinical indicators of mortality better predicted survival, compared to only adding CMD or DPVh &lt; 75 cm/s (p &lt; 0.0001 and p = 0.03, respectively).

Conclusion

A normal CFVR could hide detection of microvasculopathy with high flow resistance and low flow velocities at rest. This microvasculopathy seems to be secondary to factors unrelated to HT (less rejections and more often diabetes). The combined use of CFVR and CCFVR provides more complete clinical and prognostic information on coronary microvasculopathy in HT.

Cardiac ischemia on-a-chip to investigate cellular and molecular response of myocardial tissue under hypoxia

Tissue engineering has enabled the development of advanced and physiologically relevant models of cardiovascular diseases, with advantages over conventional 2D in vitro assays. We have previously demonstrated development of a heart on-a-chip microfluidic model with mature 3D anisotropic tissue formation that incorporates both stem cell-derived cardiomyocytes and cardiac fibroblasts within a collagen-based hydrogel. Using this platform, we herein present a model of myocardial ischemia on-a-chip, that recapitulates ischemic insult through exposure of mature 3D cardiac tissues to hypoxic environments. We report extensive validation and molecular-level analyses of the model in its ability to recapitulate myocardial ischemia in response to hypoxia, demonstrating the 1) induction of tissue fibrosis through upregulation of contractile fibers, 2) dysregulation in tissue contraction through functional assessment, 3) upregulation of hypoxia-response genes and downregulation of contractile-specific genes through targeted qPCR, and 4) transcriptomic pathway regulation of hypoxic tissues. Further, we investigated the complex response of ischemic myocardial tissues to reperfusion, identifying 5) cell toxicity, 6) sustained contractile irregularities, as well as 7) re-establishment of lactate levels and 8) gene expression, in hypoxic tissues in response to ischemia reperfusion injury.

Hypoxia signaling and oxygen metabolism in cardio-oncology

Cardio-oncology is a rapidly growing field in cardiology that focuses on the management of cardiovascular toxicities associated with cancer-directed therapies. Tumor hypoxia is a central driver of pathologic tumor growth, metastasis, and chemo-resistance. In addition, conditions that mimic hypoxia (pseudo-hypoxia) play a causal role in the pathogenesis of numerous types of cancer, including renal cell carcinoma. Therefore, therapies targeted at hypoxia signaling pathways have emerged over the past several years. Though efficacious, these therapies are associated with significant cardiovascular toxicities, ranging from hypertension to cardiomyopathy. This review focuses on oxygen metabolism in tumorigenesis, the role of targeting hypoxia signaling in cancer therapy, and the relevance of oxygen metabolism in cardio-oncology. This review will specifically focus on hypoxia signaling mediated by hypoxia-inducible factors and the prolyl hydroxylase oxygen-sensing enzymes, the cardiovascular effects of specific cancer targeted therapies mediated on VEGF and HIF signaling, hypoxic signaling in cardiovascular disease, and the role of oxygen in anthracycline cardiotoxicity. The implications of these therapies on myocardial biology and cardiac function are discussed, underlining the fine balance of hypoxia signaling in cardiac homeostasis. Understanding these cardiovascular toxicities will be important to optimize treatment for cancer patients while mitigating potentially severe cardiovascular side effects.

New Imaging Signatures of Cardiac Alterations in Ischaemic Heart Disease and Cerebrovascular Disease Using CMR Radiomics

Background: Ischaemic heart disease (IHD) and cerebrovascular disease are two closely inter-related clinical entities. Cardiovascular magnetic resonance (CMR) radiomics may capture subtle cardiac changes associated with these two diseases providing new insights into the brain-heart interactions. Objective: To define the CMR radiomics signatures for IHD and cerebrovascular disease and study their incremental value for disease discrimination over conventional CMR indices. Methods: We analysed CMR images of UK Biobank's subjects with pre-existing IHD, ischaemic cerebrovascular disease, myocardial infarction (MI), and ischaemic stroke (IS) (n = 779, 267, 525, and 107, respectively). Each disease group was compared with an equal number of healthy controls. We extracted 446 shape, first-order, and texture radiomics features from three regions of interest (right ventricle, left ventricle, and left ventricular myocardium) in end-diastole and end-systole defined from segmentation of short-axis cine images. Systematic feature selection combined with machine learning (ML) algorithms (support vector machine and random forest) and 10-fold cross-validation tests were used to build the radiomics signature for each condition. We compared the discriminatory power achieved by the radiomics signature with conventional indices for each disease group, using the area under the curve (AUC), receiver operating characteristic (ROC) analysis, and paired t-test for statistical significance. A third model combining both radiomics and conventional indices was also evaluated. Results: In all the study groups, radiomics signatures provided a significantly better disease discrimination than conventional indices, as suggested by AUC (IHD:0.82 vs. 0.75; cerebrovascular disease: 0.79 vs. 0.77; MI: 0.87 vs. 0.79, and IS: 0.81 vs. 0.72). Similar results were observed with the combined models. In IHD and MI, LV shape radiomics were dominant. However, in IS and cerebrovascular disease, the combination of shape and intensity-based features improved the disease discrimination. A notable overlap of the radiomics signatures of IHD and cerebrovascular disease was also found. Conclusions: This study demonstrates the potential value of CMR radiomics over conventional indices in detecting subtle cardiac changes associated with chronic ischaemic processes involving the brain and heart, even in the presence of more heterogeneous clinical pictures. Radiomics analysis might also improve our understanding of the complex mechanisms behind the brain-heart interactions during ischaemia.

Unfolded protein response during cardiovascular disorders: a tilt towards pro-survival and cellular homeostasis

The endoplasmic reticulum (ER) is an organelle that orchestrates the production and proper assembly of an extensive types of secretory and membrane proteins. Endoplasmic reticulum stress is conventionally related to prolonged disruption in the protein folding machinery resulting in the accumulation of unfolded proteins in the ER. This disruption is often manifested due to oxidative stress, Ca²⁺ leakage, iron imbalance, disease conditions which in turn hampers the cellular homeostasis and induces cellular apoptosis. A mild ER stress is often reverted back to normal. However, cells retaliate to acute ER stress by activating the unfolded protein response (UPR) which comprises three signaling pathways, Activating transcription factor 6 (ATF6), inositol requiring enzyme 1 alpha (IRE1α), and protein kinase RNA-activated-like ER kinase (PERK). The UPR response participates in both protective and pro-apoptotic responses and not much is known about the mechanistic aspects of the switch from pro-survival to pro-apoptosis. When ER stress outpaces UPR response then cell apoptosis prevails which often leads to the development of various diseases including cardiomyopathies. Therefore, it is important to identify molecules that modulate the UPR that may serve as promising tools towards effective treatment of cardiovascular diseases. In this review, we elucidated the latest advances in construing the contribution imparted by the three arms of UPR to combat the adverse environment in the ER to restore cellular homeostasis during cardiomyopathies. We also summarized the various therapeutic agents that plays crucial role in tilting the UPR response towards pro-survival.

Cardiac Dysfunction in Severely Burned Patients: Current Understanding of Etiology, Pathophysiology, and Treatment

Patients who experience severe burn injuries face a massive inflammatory response resulting in hemodynamic and cardiovascular complications. Even after immediate and appropriate resuscitation, removal of burn eschar and covering of open areas, burn patients remain at high risk for serious morbidity and mortality. As a result of the massive fluid shifts following the initial injury, along with large volume fluid resuscitation, the cardiovascular system is critically affected. Further, increased inflammation, catecholamine surge, and hypermetabolic syndrome impact cardiac dysfunction, which worsens outcomes of burn patients. This review aimed to summarize the current knowledge about the effect of burns on the cardiovascular system.A comprehensive search of the PubMed and Embase databases and manual review of articles involving effects of burns on the cardiovascular system was conducted.Many burn units use multimodal monitors (e.g., transpulmonary thermodilution) to assess hemodynamics and optimize cardiovascular function. Echocardiography is often used for additional evaluations of hemodynamically unstable patients to assess systolic and diastolic function. Due to its noninvasive character, echocardiography can be repeated easily, which allows us to follow patients longitudinally.The use of anabolic and anticatabolic agents has been shown to be beneficial for short- and long-term outcomes of burn survivors. Administration of propranolol (non-selective β-receptor antagonist) or oxandrolone (synthetic testosterone) for up to 12 months post-burn counteracts hypermetabolism during hospital stay and improves cardiac function.A comprehensive understanding of how burns lead to cardiac dysfunction and new therapeutic options could contribute to better outcomes in this patient population.

Expert consensus on peri-operative myocardial injury screening in noncardiac surgery: A literature review

Peri-operative myocardial injury, detected by dynamic and elevated cardiac troponin (cTn) concentrations, is a common complication of noncardiac surgery that is strongly associated with 30-day mortality. Although active screening for peri-operative myocardial injury has been suggested in recent guidelines, clinical implementation remains tentative due to a lack of examples on how to tackle such an interdisciplinary project at a local level. Moreover, consensus on which assay and cTn cut-off values should be used has not yet been reached, and guidance on whom to screen is lacking. In this article, we aim to summarise local examples of successfully implemented cTn screening practices and review the current literature in order to provide information and suggestions for patient selection, organisation of a screening programme, caveats and a potential management pathway.

Phytochemical Profile, Antioxidant, Cardioprotective and Nephroprotective Activity of Romanian Chicory Extract

The present study analyzed the methanol extract and tincture obtained from the spontaneous Romanian Cichorium intybus species, in order to evaluate polyphenols content and some biological properties. Chromatographic and spectrophotometric methods were used for the analysis of polyphenols and the antioxidant capacity was assessed in vitro with DPPH● (2,2-diphenyl-picrylhydrazil) and FRAP (ferric-reducing antioxidant power) tests. The cardio-protective effects of Cichorii herba tincture on myocardial ischemia induced by isoprenaline and nephroprotection on renal failure induced by gentamicin were evaluated on rats. Also, aspartate aminotrasferase (AST), alanine aminotransferase (ALT), creatine kinase-MB (CK-MB) and creatinine clearance (CrCl) were measured. The antioxidant effect was evaluated by determining total oxidative stress (TOS), oxidative stress index (OSI, total antioxidant capacity (TAC), malondyaldehide (MDA), total thiols (SH) and total nitrites and nitrates (NOx). Cichoric acid was the main polyphenolic compound. The extracts had moderate in vitro antioxidant activity but the in vivo antioxidant and anti-inflammatory effects were significant and associated with myocardial and renal dysfunction improvement. The results were attributed to the content of polyphenols in the extracts, for which reason C. intybus may be considered an important raw material for pharmaceuticals formulations recommended in the prevention or treatment of heart or kidney diseases.

Rationale, experimental data, and emerging clinical evidence on early and preventive use of levosimendan in patients with ventricular dysfunction

Acute ventricular dysfunction (AVD) is a complex condition with substantial morbidity and mortality, still featuring unique therapeutic challenges. Levosimendan is a calcium sensitizer and ATP-dependent potassium channel opener that was developed as an inodilating drug for the treatment of acute heart failure and cardiogenic shock. Differently from other more widely used inotropic agents, levosimendan has some exclusive characteristics, in terms of mechanisms of action, pharmacodynamic profile, and haemodynamic effects. This may have important clinical implications. In particular, in patients with AVD or in patients with pre-existing severe ventricular impairment undergoing planned myocardial stress, the administration of levosimendan before the onset of overt symptoms or before cardiovascular therapeutic procedures may have the potential to bridge the patient through the critical phase. In this review, we will focus on the rationale, the existing experimental data, and the emerging clinical experience supporting an early, even preventive use of levosimendan in severe ventricular dysfunction, beyond its recognized indications.

Determining the Significance of Coronary Plaque Lesions: Physiological Stenosis Severity and Plaque Characteristics

The evaluation of coronary lesions has evolved in recent years. Physiologic-guided revascularization (particularly with pressure-derived fractional flow reserve (FFR)) has led to superior outcomes compared to traditional angiographic assessment. A greater importance, therefore, has been placed on the functional significance of an epicardial lesion. Despite the improvements in the limitations of angiography, insights into the relationship between hemodynamic significance and plaque morphology at the lesion level has shown that determining the implications of epicardial lesions is rather complex. Investigators have sought greater understanding by correlating ischemia quantified by FFR with plaque characteristics determined on invasive and non-invasive modalities. We review the background of the use of these diagnostic tools in coronary artery disease and discuss the implications of analyzing physiological stenosis severity and plaque characteristics concurrently.

Improvements in Key Cardiopulmonary Exercise Testing Variables Following Cardiac Rehabilitation in Patients With Coronary Artery Disease

PURPOSE

Improvements in cardiorespiratory fitness ((Equation is included in full-text article.)O2peak) post-cardiac rehabilitation (post-CR) are used to gauge therapeutic efficacy. The aim of the present study was to assess the effect of supervised CR on other cardiopulmonary exercise testing (CPX) variables, specifically those that reflect ventilatory efficiency and (Equation is included in full-text article.)O2 changes in relation to changes in work rate (WR).

METHODS

Patients (n = 142; mean age 63 ± 9 y; 23% female) with coronary artery disease (CAD) participated in supervised CR for 3 to 6 mo completing 60 ± 17 sessions (range: 32-96 sessions), with intensity derived from the baseline CPX. CPX was completed at baseline and post-CR on a cycle ergometer. The minimum heart rate (HR) during cycling was set 5 to 10 beats/min above the HR at ventilatory anaerobic threshold (VAT) while the maximum HR remained below the ischemic threshold observed during CPX, and this intensity was maintained for 25 min. (Equation is included in full-text article.)O2peak, peak O2 pulse, the minute ventilation/carbon dioxide production ((Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2) slope, the oxygen uptake efficiency slope (OUES), and the Δ(Equation is included in full-text article.)O2/ΔWR slope were determined at baseline and post-CR.

RESULTS

Following CR, there were significant improvements (all P < .001) in (Equation is included in full-text article.)O2peak (17.7 ± 4.7 mL/kg/min vs 20.9 ± 5.4 mL/kg/min), peak O2 pulse (11.6 ± 3.2 mL/beat vs 13.4 ± 3.6 mL/beat), (Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2 slope (28.4 ± 5.3 vs 27.5 ± 4.7), OUES (1.8 ± 0.5 vs 2.0 ± 0.6), and Δ(Equation is included in full-text article.)O2/ΔWR slope (9.1 ± 1.2 mL/min/W vs 9.6 ± 1.1 mL/min/W).

CONCLUSION

Key markers of ventilatory efficiency and (Equation is included in full-text article.)O2 kinetics during CPX significantly improve following CR. Expanding the list of variables assessed via CPX may provide better resolution in validation of CR therapeutic efficacy in patients with CAD.

Metabolic Disturbances Identified in Plasma Samples from ST-Segment Elevation Myocardial Infarction Patients

ST-segment elevation myocardial infarction (STEMI) is the most severe form of myocardial infarction (MI) and the main contributor to morbidity and mortality caused by MI worldwide. Frequently, STEMI is caused by complete and persistent occlusion of a coronary artery by a blood clot, which promotes heart damage. STEMI impairment triggers changes in gene transcription, protein expression, and metabolite concentrations, which grants a biosignature to the heart dysfunction. There is a major interest in identifying novel biomarkers that could improve the diagnosis of STEMI. In this study, the phenotypic characterization of STEMI patients (n = 15) and healthy individuals (n = 19) was performed, using a target metabolomics approach. Plasma samples were analyzed by UPLC-MS/MS (ultra-high-performance liquid chromatography-tandem mass spectrometry) and FIA-MS (MS-based flow injection analysis). The goal was to identify novel plasma biomarkers and metabolic signatures underlying STEMI. Concentrations of phosphatidylcholines, lysophosphatidylcholines, sphingomyelins, and biogenic amines were altered in STEMI patients in relation to healthy subjects. Also, after multivariate analysis, it was possible to identify alterations in the glycerophospholipids, alpha-linolenic acid, and sphingolipid metabolisms in STEMI patients.

Pressure overload leads to coronary plaque formation, progression, and myocardial events in ApoE-/- mice

Hypercholesterolemia and hypertension are two major risk factors for coronary artery diseases, which remain the major cause of mortality in the industrialized world. Current animal models of atherosclerosis do not recapitulate coronary plaque disruption, thrombosis, and myocardial infarction occurring in humans. Recently, we demonstrated that exposure of the heart to high pressure, by transverse aortic constriction (TAC), induced coronary lesions in ApoE-/- mice on chow diet. The aim of this study was to characterize the magnitude and location of coronary lesions in ApoE-/- mice after TAC and to assess the susceptibility of coronary plaque to disruption, leading to myocardial events. Here, we describe a reliable pathological condition in mice characterized by the development of coronary lesions and its progression, leading to myocardial infarction; this model better recapitulates human disease. Following TAC surgery, about 90% of ApoE-/- mice developed coronary lesions, especially in the left anterior descending artery, with 59% of the mice manifesting a different magnitude of LAD stenosis. Myocardial events, identified in 74% of the mice, were mainly due to coronary plaque thrombosis and occlusion. That TAC-induced development and progression of coronary lesions in ApoE-/- mice, leading to myocardial events, represents a potentially novel and important tool to investigate the development of coronary lesions and its sequelae in a setting that better resemble human conditions.

Left ventricular hypertrophy contributes to Myocardial Ischemia in Non-obstructive Coronary Artery Disease (the MicroCAD study)

BACKGROUND

The underlying mechanisms causing myocardial ischemia in non-obstructive coronary artery disease (CAD) are still unclear. We explored whether left ventricular hypertrophy (LVH) was associated with myocardial ischemia in patients with stable angina and non-obstructive CAD.

METHODS

132 patients (mean age 63 ± 8 years, 56% women) with stable angina and non-obstructive CAD diagnosed as <50% stenosis by coronary computed tomography angiography (CCTA) underwent myocardial contrast stress echocardiography. Left ventricular (LV) hypertrophy (LVH) was identified by LV mass index >46.7 g/m^2.7 in women and >49.2 g/m^2.7 in men. Patients were grouped according to presence or absence of myocardial ischemia by myocardial contrast stress echocardiography. The number of LV segments with ischemia at peak stress was taken as a measure of the extent of myocardial ischemia.

RESULTS

Myocardial ischemia was found in 52% of patients, with on average 5 ± 3 ischemic LV segments per patient. The group with myocardial ischemia had higher prevalence of LVH (23 vs. 10%, p = 0.035), while age, sex and prevalence of hypertension did not differ between groups (all p > 0.05). In multivariable regression analyses, LVH was associated with presence of myocardial ischemia (odds ratio 3.27, 95% confidence interval [1.11-9.60], p = 0.031), and larger extent of myocardial ischemia (β = 0.22, p = 0.012), independent of confounders including age, hypertension, obesity, hypercholesterolemia, calcium score and segment involvement score by CCTA.

CONCLUSIONS

LVH was independently associated with both presence and extent of myocardial ischemia in patients with stable angina and non-obstructive CAD by CCTA. These results suggest LVH as an independent contributor to myocardial ischemia in non-obstructive CAD.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, identifier NCT018535271.

Analysis of ischaemic crisis using the informational causal entropy-complexity plane

In the present work, an ischaemic process, mainly focused on the reperfusion stage, is studied using the informational causal entropy-complexity plane. Ischaemic wall behavior under this condition was analyzed through wall thickness and ventricular pressure variations, acquired during an obstructive flow maneuver performed on left coronary arteries of surgically instrumented animals. Basically, the induction of ischaemia depends on the temporary occlusion of left circumflex coronary artery (which supplies blood to the posterior left ventricular wall) that lasts for a few seconds. Normal perfusion of the wall was then reestablished while the anterior ventricular wall remained adequately perfused during the entire maneuver. The obtained results showed that system dynamics could be effectively described by entropy-complexity loops, in both abnormally and well perfused walls. These results could contribute to making an objective indicator of the recovery heart tissues after an ischaemic process, in a way to quantify the restoration of myocardial behavior after the supply of oxygen to the ventricular wall was suppressed for a brief period.

Progressive Decrease in Coronary Vascular Function Associated With Type 2 Diabetic Heart Disease

Background: The causal factors underpinning the onset and progression of diabetic heart disease (DHD) remain to be fully elucidated. Myocardial function is critically dependent on optimal coronary blood flow. Considering vascular disease occurs early in diabetes due to endothelial dysfunction, this study aimed to determine whether impaired coronary perfusion contributes to the origins of myocardial dysfunction in DHD, or whether coronary and cardiac dysfunction are independent pathologies associated with diabetes.

Methods: Synchrotron radiation microangiography was used to image the coronary circulation of type-2 diabetic db/db and non-diabetic db/+ mice in vivo at 8, 16, and 24 weeks of age. We further assessed vascular function based on the vasodilatory responses to acetylcholine (ACh, 3 μg/kg/min), sodium nitroprusside (SNP, 5 μg/kg/min) and the Rho-kinase inhibitor, fasudil (20 mg/kg, i.v.). Cardiac function was assessed using echocardiography, and cardiac eNOS and ROCK expression were measured using immunohistochemistry.

Results: Coronary and cardiac function were normal in 8-week-old diabetic mice. However, by 16 weeks of age, diabetic mice had advanced cardiac dysfunction. In comparison, normal coronary perfusion was preserved in diabetes until 24 weeks of age. Moreover, only the 24-week-old diabetic mice showed clear evidence of advanced coronary vascular dysfunction, based on (i) the absence of a vasodilatory response to ACh, and (ii) an exaggerated vasodilatory response to fasudil. Interestingly, fasudil also restored normal coronary perfusion in the 24-week-old diabetic heart by restoring blood flow to previously constricted vessels (diameter < 100 μm). Importantly, there was a ubiquitous decrease, and increase, in the cardiac expression of eNOS and ROCK, respectively.

Conclusion: These results suggest that both cardiac and coronary dysfunction appear to have independent origins associated with diabetes and Rho-kinase pathway may be playing a role in the onset and progression of DHD.

Ghrelin Preserves Ischemia-Induced Vasodilation of Male Rat Coronary Vessels Following β-Adrenergic Receptor Blockade

Acute myocardial infarction (MI) triggers an adverse increase in cardiac sympathetic nerve activity (SNA). Whereas β-adrenergic receptor (β-AR) blockers are routinely used for the management of MI, they may also counter β-AR-mediated vasodilation of coronary vessels. We have reported that ghrelin prevents sympathetic activation following MI. Whether ghrelin modulates coronary vascular tone following MI, either through the modulation of SNA or directly as a vasoactive mediator, has never been addressed. We used synchrotron microangiography to image coronary perfusion and vessel internal diameter (ID) in anesthetized Sprague-Dawley rats, before and then again 30 minutes after induction of an MI (left coronary artery ligation). Rats were injected with either saline or ghrelin (150 µg/kg, subcutaneously), immediately following the MI or sham surgery. Coronary angiograms were also recorded following β-AR blockade (propranolol, 2 mg/kg, intravenously). Finally, wire myography was used to assess the effect of ghrelin on vascular tone in isolated human internal mammary arteries (IMAs). Acute MI enhanced coronary perfusion to nonischemicregions through dilation of small arterioles (ID 50 to 250 µm) and microvessel recruitment, irrespective of ghrelin treatment. In ghrelin-treated rats, β-AR blockade did not alter the ischemia-induced vasodilation, yet in saline-treated rats, β-AR blockade abolished the vasodilation of small arterioles. Finally, ghrelin caused a dose-dependent vasodilation of IMA rings (preconstricted with phenylephrine). In summary, this study highlights ghrelin as a promising adjunct therapy that can be used in combination with routine β-AR blockade treatment for preserving coronary blood flow and cardiac performance in patients who suffer an acute MI.

Cardiogenic Shock: Recent Developments and Significant Knowledge Gaps

PURPOSE OF REVIEW

Patients with cardiogenic shock (CS) continue to have high rates of morbidity and mortality. We aimed to describe current principles in the management of CS including coronary revascularization, medical management, mechanical circulatory support, and supportive care.

RECENT FINDINGS

Revascularization is still recommended, but trials have not found a benefit in the revascularization of nonculprit artery lesions. New mechanical circulatory support options are available, but optimal use remains uncertain. Overall improvement in outcomes appears to have plateaued. There remain substantial knowledge gaps about the management of CS. The ideal timing and selection criteria for mechanical support remain under-developed. There has been little systematic study to inform medical management or supportive care of this patient population. A more expansive research focus is necessary to improve the care of CS.

Erectile Dysfunction and Ischaemic Heart Disease

Erectile dysfunction (ED) is a common disorder that affects the quality of life of many patients. It is prevalent in more than half of males aged over 60 years. Increasing evidence suggests that ED is predominantly a vascular disorder. Endothelial dysfunction seems to be the common pathological process causing ED. Many common risk factors for atherosclerosis such as diabetes, hypertension, smoking, obesity and hyperlipidaemia are prevalent in patients with ED and so management of these common cardiovascular risk factors can potentially prevent ED. Phosphodiesterase type 5 inhibitors provide short-term change of haemodynamic factors to help initiate and maintain penile erection. They have been shown to be an effective and safe treatment strategy for ED in patients with heart disease, including those with ischaemic heart disease and hypertension.

Role of Calcium Channel Blockers in Myocardial Preconditioning

Coronary heart disease is the leading cause of mortality and morbidity worldwide. The effects of coronary heart disease are usually attributable to the detrimental effects of acute myocardial ischaemia-reperfusion injury. Newer strategies such as ischaemic or pharmacological preconditioning have been shown to condition the myocardium to ischaemia-reperfusion injury and thus reduce the final infarct size. This review investigates the role of calcium channel blockers in myocardial preconditioning. Additionally, special attention is given to nicorandil whose mechanism of action may be associated with the cardioprotective effects of preconditioning. There are still many uncertainties in understanding the role of these agents in preconditioning, but future research in this direction will certainly help reduce coronary heart disease.

Nanomedicine for the cardiac myocyte: Where are we?

Biomedical achievements in the last few decades, leading to successful therapeutic interventions, have considerably improved human life expectancy. Nevertheless, the increasing load and the still suboptimal outcome for patients with cardiac dysfunction underlines the relevance of continuous research to develop novel therapeutics for these diseases. In this context, the field of nanomedicine has attracted a lot of attention due to the potential novel treatment possibilities, such as controlled and sustained release, tissue targeting, and drug protection from degradation. For cardiac myocytes, which constitute the majority of the heart by mass and are the contractile unit, new options have been explored in terms of the use of nanomaterials (NMs) for therapy, diagnosis, and tissue engineering. This review focuses on the advances of nanomedicine targeted to the cardiac myocyte: first presenting the NMs used and the principal cardiac myocyte-based afflictions, followed by an overview of key advances in the field, including NMs interactions with the cardiac myocyte, therapy delivery, diagnosis based on imaging, and tissue engineering for tissue repair and heart-on-a-chip devices.

Contribution of lectin-like oxidized low-density lipoprotein receptor-1 and LOX-1 modulating compounds to vascular diseases

The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the major receptor for binding and uptake of oxidized low-density lipoprotein (oxLDL) in endothelial cells. LOX-1 is also expressed in macrophages, smooth muscle cells and platelets. Following internalization of oxLDL, LOX-1 initiates a vicious cycle from activation of pro-inflammatory signaling pathways, thus promoting an increased reactive oxygen species formation and secretion of pro-inflammatory cytokines. LOX-1 plays a pivotal role in the development of endothelial dysfunction, foam cell and advanced lesions formation as well as in myocardial ischemia. Furthermore, it is known that LOX-1 plays a pivotal role in mitochondrial DNA damage, vascular cell apoptosis, and autophagy. A large number of studies provide evidence of a LOX-1's role in endothelial dysfunction, hypertension, diabetes, and obesity. In addition, novel insights into LOX-1 ligands and the activated signaling pathways have been gained. Recent studies have shown an interaction of LOX-1 with microRNA's, thus providing novel tools to regulate LOX-1 function. Because LOX-1 is increased in atherosclerotic plaques and contributes to endothelial dysfunction, several compounds were tested in vivo and in vitro to modulate the LOX-1 expression in therapeutic approaches.

WDR26 promotes mitophagy of cardiomyocytes induced by hypoxia through Parkin translocation

Myocardial ischemia is a heart condition caused by reduction of blood flow to the heart, preventing heart from receiving enough oxygen. Myocardial ischemia is the most common cause of death globally. Heart ischemic preconditioning (IPC) has a protective effect against myocardial cell death induced by ischemia and ischemia-reperfusion injury. WDR26 has recently been identified as a protein that is increased following rat cardiac IPC. WDR26 can promote the proliferation of H9c2 cells and protect cardiomyocytes against oxidative stress through inhibiting apoptosis. However, its role in myocardial ischemia is unclear. The aim of this study was to explore the role of WDR26 in myocardial ischemia and H9c2 cell hypoxia. Our results showed that WDR26 is induced by myocardial ischemia and H9c2 cell hypoxia. WDR26 protects H9c2 cells against hypoxia injury through inhibiting LDH release and increasing cell viability. WDR26 promotes hypoxia-induced autophagy in hypoxia of H9c2 cells. We further demonstrated that in H9c2 cell hypoxia, WDR26 increases mitochondrial membrane potential, thereby increases Parkin translocation of mitochondria. After Parkin is translocated at mitochondria, WDR26 can increase mitochondrial protein ubiquitination in hypoxia of H9c2 cells. WDR26 is a mediator of response to hypoxia, and WDR26 plays an important role in hypoxia-mediated autophagy and mitophagy. This study provides novel insights into the protective role of WDR26 in cardiomyocyte injury during hypoxia. WDR26 may serve as a potential target for the treatment of myocardial ischemia.

[Cardioprotection via the arm? : How a blood pressure cuff decreases infarct sizes]

Cardiovascular diseases and especially myocardial infarctions are responsible for a high morbidity and mortality throughout Europe. An essential aspect of myocardial infarction is ischemia/reperfusion injury which represents the necrosis of myocytes following reperfusion. One possible option to counteract ischemia/reperfusion injury is the much researched process of remote ischemic conditioning (RIC), whereby a certain tissue (e.g. skeletal muscle) is subjected to several cycles of short periods (e.g. 5 min) of ischemia and reperfusion and leads to the protection of another organ (e.g. the heart). Despite substantial efforts to elucidate the underlying mechanisms during the last decades, this phenomenon is not yet completely understood. Clinical studies mainly concentrated on laboratory and radiological parameters, which led to better understanding of RIC; however, large clinical studies evaluating the possible influence on mortality are still lacking. This review article provides an introduction to RIC and summarizes the current understanding of known pathomechanisms and the results of important clinical studies.

Increase in ultrasonic intensity of blood speckle across moderate coronary artery stenosis is an independent predictor of functional coronary artery stenosis measured by fractional flow reserve: pilot study

Background and Aims

The degree of coronary artery stenosis should be assessed both anatomically and functionally. We observed that the intensity of blood speckle (IBS) on intravascular ultrasound (IVUS) is low proximal to a coronary artery stenosis, and high distal to the stenosis. We defined step-up IBS as the distal minus the proximal IBS, and speculated that this new parameter could be used for the functional evaluation of stenosis on IVUS. The aims of this study were to assess the relationships between step-up IBS and factors that affect coronary blood flow, and between step-up IBS and fractional flow reserve (FFR).

Methods and Results

This study enrolled 36 consecutive patients with angina who had a single moderate stenosis in the left anterior descending artery. All patients were evaluated by integrated backscatter IVUS and intracoronary pressure measurements. FFR was calculated from measurements using a coronary pressure wire during hyperemia. Conventional gray-scale IVUS images were recorded, and integrated backscatter was measured in three cross-sectional slices proximal and distal to the stenosis. Step-up IBS was calculated as (mean distal integrated backscatter value) − (mean proximal integrated backscatter value). Stepwise multiple linear regression analysis showed that the heart rate (r = 0.45, P = 0.005), ejection fraction (r = −0.39, P = 0.01), and hemoglobin level (r = −0.32, P = 0.04) were independently correlated with step-up IBS, whereas proximal and distal IBS were not associated with these factors. There was a strong inverse correlation between step-up IBS and FFR (r = −0.84, P < 0.001), which remained significant on stepwise multiple linear regression analysis.

Conclusions

The newly defined parameter of step-up IBS is potentially useful for the functional assessment of coronary artery stenosis.

Diagnostic value of Flash dual-source CT coronary artery imaging combined with dual-energy myocardial perfusion imaging for coronary heart disease

The present study aimed to investigate the diagnostic value of Flash dual-source CT coronary angiography (DS-CTA) combined with dual-energy myocardial perfusion imaging (DS-CTP) for coronary heart disease (CHD), as a single-stage examination. A total of 60 patients with CHD underwent DS-CT examination, as well as coronary angiography (CAG), as the reference standard. The patients were divided into <50% and ≥50% stenosis groups based on their coronary angiograms. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the method for diagnosing stenosis of ≥50% were evaluated via DS-CTA combined with DS-CTP. Of the 60 patients, 59 showed satisfactory results that conformed to the diagnostic requirements. Using CAG as the reference standard, the sensitivity, specificity and positive and negative predictive values of the Flash DS-CT results in the ≥50% vascular stenosis group were 83.7, 92.7, 88.9 and 89.1%, respectively. The respective values for DS-CTA combined with DS-CTP for diagnosing CHD were 94.2, 91.1, 88.0 and 95.8%. Therefore, the results obtained indicate that DS-CTA combined with DS-CTP has a high diagnostic value for CHD. DS-CT is advantageous for diagnosing and prognosticating CHD.

Non-invasive imaging in coronary artery disease including anatomical and functional evaluation of ischaemia and viability assessment

Coronary artery disease has an important impact on the morbidity and mortality statistics and health economics worldwide. Diagnosis of coronary artery disease is important in risk stratification and guides further management. Invasive coronary angiography is the traditional method of imaging the coronary arteries and remains the gold standard. It detects luminal stenosis but provides little information about the vessel wall or plaques. Besides, not all anatomical lesions are functionally significant. This has lent itself to a wide variety of imaging techniques to identify and assess a flow-limiting stenosis. The approach to diagnosis of coronary artery disease is broadly based on anatomical and functional imaging. Coronary CT and MRI of coronary arteries provide an anatomical assessment of coronary stenosis. Coronary calcium score and coronary CT assess subclinical atherosclerosis by assessing the atherosclerotic plaque burden. The haemodynamic significance of a coronary artery stenosis can be assessed by stress radioisotope studies, stress echocardiography and stress MRI. The more recent literature also focuses on plaque assessment and identification of plaques that are likely to give rise to an acute coronary syndrome. There is an explosion of literature on the merits and limitations of the different imaging modalities. This review article will provide an overview of all the imaging modalities in the diagnosis of coronary artery disease.

Usefulness of contrast echocardiography for predicting the severity of angiographic coronary disease in non-ST-elevation myocardial infarction

Guidelines recommend coronary angiography in patients with non-ST-elevation myocardial infarction (NSTEMI) within 24 to 72 hours, a requirement that cannot always be met. The aim of this study was to evaluate the potential use of contrast echocardiography in prioritizing these patients by identifying those with NSTEMI and angiographically severe coronary artery disease (CAD). Echocardiography was performed before coronary angiography in 110 patients with NSTEMI (67 ± 12 years old, 31% women). Segmental myocardial perfusion and wall motion was scored using a 17-segment left ventricular model. CAD was assessed by quantitative coronary angiography. In the total study population, median troponin T level was 0.27 μg/L (0.13 to 0.86) and Thrombolysis In Myocardial Infarction risk score 3.1 ± 1.5. By quantitative coronary angiography 15% had normal coronary angiographic findings, whereas 1-, 2-, and 3-vessel disease were present in 35%, 27%, and 23%, respectively. Severe CAD (left main stem stenosis, 3-vessel disease, or multivessel disease including proximal stenosis in left anterior descending artery) was found in 42%. Number of segments with hypoperfusion increased with CAD severity from 4.1 ± 2.0 in patients with normal coronary arteries to 5.9 ± 2.4, 7.8 ± 3.5, and 10.4 ± 2.8 in patients with 1-, 2-, and 3-vessel disease, respectively (p<0.01). In multiple logistic regression analysis risk of severe CAD increased by 39% for every additional hypoperfused segment by echocardiography independent of wall motion abnormalities and Thrombolysis In Myocardial Infarction risk score. In conclusion, contrast echocardiography may be used for prediction of angiographic CAD severity in patients with NSTEMI awaiting coronary angiography.

Quantitative contrast stress echocardiography in assessment of restenosis after percutaneous coronary intervention in stable coronary artery disease

AIMS

Quantitative contrast stress echocardiography (CSE) can assess regional myocardial perfusion. The aim of this study was to evaluate the performance of quantitative CSE in the detection of restenosis after percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Thirty-three patients with stable coronary artery disease, scheduled for PCI, underwent CSE and quantitative coronary angiography (QCA) before and 9 months after PCI. Regional myocardial perfusion was analysed blinded to QCA results. QCA identified 38 significant stenoses (> or =50% diameter reduction). Before PCI, perfusion during stress was significantly reduced in regions supplied by stenotic arteries; blood flow velocity (Deltabeta) -3.9 (-9.0 to 0.5) s(-1), perfusion rate (DeltaA x beta) -175.0 (-518.0 to 58.5) s(-1), and refilling time (Deltart) 210 (-22 to 452)ms, compared with the perfusion increase seen in regions supplied by non-stenotic arteries; Deltabeta 1.6 (-0.7 to 4.4) s(-1), DeltaA x beta 151.7 (-67.0 to 300.5) s(-1), and Deltart -47 (-195 to 89) ms, all P < 0.05. At follow-up, regional stress-induced perfusion improved in 29 regions with successful PCI; Deltabeta 0.1 (-2.7 to 3.6), DeltaA x beta 30.5 (-133.3 to 232.1), and Deltart -99 (-247 to 125), all P < or = 0.01, although there was no improvement in nine regions with restenosis; Deltabeta 0.9 (-1.5 to 5.3), DeltaAxbeta 65.7 (-40.8 to 412.6), and Deltart -79 (-268 to 163), P = NS.

CONCLUSION

Quantitative CSE has the potential to detect angiographically significant coronary artery stenoses as well as angiographic success after PCI.