The collateral circulation of the heart

The Importance of Pan-Immune Inflammation Value (PIV) in Predicting Coronary Collateral Circulation in Stable Coronary Artery Patients

In this study, the correlation between pan-immune-inflammation value (PIV) and coronary collateral circulation (CCC) in patients with chronic coronary syndrome (CCS) was analyzed. The study included 663 patients with CCS who underwent coronary angiography and had coronary stenosis of ≥95% in at least one major coronary vessel. The participants were divided into two groups: good CCC (Rentrop score 2-3) and poor CCC (Rentrop score 0-1). PIV score was calculated as monocyte x platelet x neutrophil/lymphocyte count. When the patient groups who developed good and poor CCC were compared, neutrophil/lymphocyte ratio (NLR) (P < .001), C-reactive protein (CRP) levels, CRP/albumin ratio (CAR) (P < .001), systemic immune-inflammation index (SII) (P < .001), and PIV (P < .001) were higher in patients with poor CCC. In multivariate logistic regression analysis, age, SII, NLR, CRP, CAR, and PIV were found to be independent predictors of poor CCC (P < .001, for all). Receiver operating characteristic (ROC) analysis demonstrated that a cut-off value of 442.2 for PIV predicted poor CCC slightly better compared to other markers, with 76.8% sensitivity and 70.1% specificity (area under ROC curve = 0.808 (95% CI: 0.764-0.851), P < .001). These findings suggest that PIV can be used as an independent predictor of CCC development.

Experimental and theoretical model of microvascular network remodeling and blood flow redistribution following minimally invasive microvessel laser ablation

Overly dense microvascular networks are treated by selective reduction of vascular elements. Inappropriate manipulation of microvessels could result in loss of host tissue function or a worsening of the clinical problem. Here, experimental, and computational models were developed to induce blood flow changes via selective artery and vein laser ablation and study the compensatory collateral flow redistribution and vessel diameter remodeling. The microvasculature was imaged non-invasively by bright-field and multi-photon laser microscopy, and optical coherence tomography pre-ablation and up to 30 days post-ablation. A theoretical model of network remodeling was developed to compute blood flow and intravascular pressure and identify vessels most susceptible to changes in flow direction. The skin microvascular remodeling patterns were consistent among the five specimens studied. Significant remodeling occurred at various time points, beginning as early as days 1-3 and continuing beyond day 20. The remodeling patterns included collateral development, venous and arterial reopening, and both outward and inward remodeling, with variations in the time frames for each mouse. In a representative specimen, immediately post-ablation, the average artery and vein diameters increased by 14% and 23%, respectively. At day 20 post-ablation, the maximum increases in arterial and venous diameters were 2.5× and 3.3×, respectively. By day 30, the average artery diameter remained 11% increased whereas the vein diameters returned to near pre-ablation values. Some arteries regenerated across the ablation sites via endothelial cell migration, while veins either reconnected or rerouted flow around the ablation site, likely depending on local pressure driving forces. In the intact network, the theoretical model predicts that the vessels that act as collaterals after flow disruption are those most sensitive to distant changes in pressure. The model results correlate with the post-ablation microvascular remodeling patterns.

Coronary Artery Occlusion with Sharp Blood Pressure Drop during General Anesthesia Induction: A Case Report

Most anesthetics reduce cardiac functions and lower blood pressure (BP), potentially causing excessive BP reduction in dehydrated patients or those with heart conditions, such as coronary artery disease (CAD). Considering the increased prevalence of cardiovascular disease with age, anesthesiologists must be cautious about BP reduction during general anesthesia in older adults. In the present case, a 76-year-old male patient with undiagnosed CAD in a hypovolemic state experienced a significant drop in systolic BP to the fifties during propofol and sevoflurane anesthesia. Despite the use of vasopressors, excessive hypotension persisted, leading to anesthesia suspension. Subsequent cardiac examinations, including computed tomography heart angio and calcium score, and coronary angiogram, revealed a near total occlusion of the proximal left anterior descending coronary artery (pLAD) and the formation of collateral circulation. After 5 days of hydration and anticoagulation medications and confirmation of normovolemic state, general anesthesia was attempted again and successfully induced; a normal BP was maintained throughout the surgery. Thus, it is important to conduct a thorough cardiac evaluation and maintain normovolemia for general anesthesia in older adults.

Experimental and Theoretical Model of Single Vessel Minimally Invasive Micro-Laser Ablation: Inducing Microvascular Network Remodeling and Blood Flow Redistribution Without Compromising Host Tissue Function

Overly dense microvascular networks are treated by selective reduction of vascular elements. Inappropriate manipulation of microvessels could result in loss of host tissue function or a worsening of the clinical problem. Here, experimental, and computational models were developed to induce blood flow changes via selective artery and vein laser ablation and study the compensatory collateral flow redistribution and vessel diameter remodeling. The microvasculature was imaged non-invasively by bright-field and multi-photon laser microscopy, and Optical Coherence Tomography pre-ablation and up to 30 days post-ablation. A theoretical model of network remodeling was developed to compute blood flow and intravascular pressure and identify vessels most susceptible to changes in flow direction. The skin microvascular remodeling patterns were consistent among the five specimens studied. Significant remodeling occurred at various time points, beginning as early as days 1-3 and continuing beyond day 20. The remodeling patterns included collateral development, venous and arterial reopening, and both outward and inward remodeling, with variations in the time frames for each mouse. In a representative specimen, immediately post-ablation, the average artery and vein diameters increased by 14% and 23%, respectively. At day 20 post-ablation, the maximum increases in arterial and venous diameters were 2.5x and 3.3x, respectively. By day 30, the average artery diameter remained 11% increased whereas the vein diameters returned to near pre-ablation values. Some arteries regenerated across the ablation sites via endothelial cell migration, while veins either reconnected or rerouted flow around the ablation site, likely depending on local pressure driving forces. In the intact network, the theoretical model predicts that the vessels that act as collaterals after flow disruption are those most sensitive to distant changes in pressure. The model results match the post-ablation microvascular remodeling patterns.

Influence of electrolyte imbalance on regional wall motion abnormalities in STEMI patients of North Indian origin

Assessing regional wall motion abnormalities (RWMA) in the myocardium may provide early diagnosis and treat chronic remodeling in STEMI patients. We assessed RWMA in 217 subjects with anterior STEMI admitted to Era University Hospital in Lucknow, UP, India. Besides abnormalities in the LAD territory, sub-sets of patients exhibited diffuse regional myocardial dysfunction. Interestingly, variations in serum electrolytes, specifically sodium and potassium, significantly affected the distribution and frequency of RWMA. Notably, RWMA occurred in the basal septum, apical septum, apex, and lateral wall in the anterior STEMI group. Additionally, the rate of regional dysfunction varied with serum urea and creatinine levels. This suggests that anterior STEMI can manifest myocardial abnormalities beyond the LAD territory. These findings indicate that ST-segment elevation might not be specific, possibly influenced by electrolyte changes affecting cardiac rhythm. Therefore, diagnosing and correcting region-specific wall motion abnormalities and electrolyte imbalances may improve outcomes in STEMI patients.

Are Thiols Useful Biomarkers for Coronary Collateral Circulation in Patients with Stable Coronary Artery Disease?

Our aim was to investigate the relationship between thiol, which is the main component of the antioxidant system, and coronary collateral circulation (CCC). Our patients consisted of people with stable coronary artery disease (sCAD) and total occlusion in at least one vessel (n = 249). We divided the patients into two groups, good and poor, according to their CCC degree. We determined that DM, total thiol, and disulfide are independent predictors of poor CCC in multivariate logistic regression analysis (OR: 1.012, 95% CI: 1.008-1.017, p < 0.001; OR: 1.022, 95% CI: 1.000-1.044, p = 0.044; OR: 2.671, 95% CI: 1.238-5.761, p = 0.012, respectively). The ROC analysis showed a cut-off value of 328.7 for native thiol regarding the prediction of poor CCC, with 67.4% specificity and 78% sensitivity. For disulfide, it revealed a cut-off value of 15.1 regarding the prediction of poor CCC, with 57.9% specificity and 69.5% sensitivity. In this study, we detected that the patients with sCAD who developed poor CCC had lower levels of native thiol, total thiol, and disulfide compared to those with good CCC. The most interesting finding of our study is that CCC formation is an effective predictor of the antioxidant cascade rather than the inflammation cascade in sCAD patients.

Increased Plasma Non-High-Density Lipoprotein Levels and Poor Coronary Collateral Circulation in Patients With Stable Coronary Artery Disease

BACKGROUND

This study investigated the relationship between coronary collateral circulation (CCC) and non-high-density lipoprotein cholesterol (non-HDL-C) in patients with stable coronary artery disease (CAD). Coronary collateral circulation plays a critical role in supporting blood flow, particularly in the ischemic myocardium. Previous studies show that non-HDL-C plays a more important role in the formation and progression of atherosclerosis than do standard lipid parameters.

METHODS

A total of 226 patients with stable CAD and stenosis of more than 95% in at least 1 epicardial coronary artery were included in the study. Rentrop classification was used to assign patients into group 1 (n = 85; poor collateral) or 2 (n = 141; good collateral). To adjust for the observed imbalance in baseline covariates between study groups, propensity-score matching was used. Covariates were diabetes, Gensini score, and angiotensin-converting enzyme inhibitor use.

RESULTS

In the propensity-matched population, the plasma non-HDL-C level (mean [SD], 177.86 [44.0] mg/dL vs 155.6 [46.21] mg/dL; P = .001) was statistically higher in the poor-collateral group. LDL-C (odds ratio [OR], 1.23; 95% CI, 1.11-1.30; P = .01), non-HDL-C (OR, 1.34; 95% CI, 1.20-1.51; P = .01), C-reactive protein (OR, 1.21; 95% CI, 1.11-1.32; P = .03), systemic immune-inflammation index (OR, 1.14; 95% CI, 1.05-1.21; P = .01), and C-reactive protein to albumin ratio (OR, 1.11; 95% CI, 1.06-1.17; P = .01) remained independent predictors of CCC in multivariate logistic regression analysis.

CONCLUSION

Non-HDL-C was an independent risk factor for developing poor CCC in stable CAD.

The association of serum uric acid/albumin ratio with the development of coronary collateral circulation in patients with chronic total occluded coronary arteries

Introduction: Coronary collateral circulation (CCC) develops in chronic total occluded (CTO) vessels and protects the myocardium against ischemia in addition to the improvement of cardiac functions. Poor CCC is related to adverse cardiac events as well as poor prognosis. Serum uric acid/albumin ratio (UAR) has emerged as a novel marker associated with poor cardiovascular outcomes. We aimed to investigate whether there was an association between UAR and poor CCC in CTO patients. Methods: This study was comprised of 212 patients with CTO (92 with poor CCC and 120 with good CCC). All patients were graded based on Rentrop scores to poor CCC (Rentrop scores 0 and 1) and good CCC (Rentrop scores 2 and 3). Results: Poor CCC patients had higher frequencies of diabetes mellitus, triglyceride levels, Syntax and Gensini scores, uric acid, and UAR and lower lymphocyte, high-density lipoprotein cholesterol, and ejection fraction when compared to good CCC patients. UAR was an independent predictor of poor CCC in CTO patients. Furthermore, UAR had a better discriminative ability for patients with poor CCC from good CCC compared to serum uric acid and albumin. Conclusion: Based on the results of the study, the UAR could be used to detect poor CCC in CTO patients.

The many roles of urgent catheter interventions: from myocardial infarction to acute stroke and pulmonary embolism

INTRODUCTION

Cardiovascular diseases (CVDs) are the leading cause of cardiovascular mortality and a major contributor to disability worldwide. The prevalence of CVDs is continuously increasing, and from 1990 to 2019, it has doubled. Global cardiovascular mortality has increased from 12.1 million in 1990 to 18.6 million cases in 2019. The development of therapeutic options for these diseases is at the forefront of interest concerning the extensive socio-economic consequences. Modern endovascular transcatheter therapeutic options contribute to the reduction of cardiovascular morbidity and mortality.

AREAS COVERED

The article concentrates on the triad of the most common causes of acute cardiovascular mortality and morbidity - myocardial infarction, ischemic stroke, and pulmonary embolism. Current evidence-based indications, specific interventional techniques, and remaining unsolved issues are reviewed and compared. A personal perspective on the possible implications for the future is provided.

EXPERT OPINION

Primary angioplasty for ST-segment elevation myocardial infarction is a well-established therapeutic option with proven mortality benefits. We suppose that catheter-based interventions for acute stroke will spread quickly from centers of excellence to routine clinical practice. We believe that ongoing research will provide a basis for the expansion of interventional treatment of pulmonary embolism soon.

Association between engagement in exercise training and peak cardiac biomarker concentrations following ST-elevation myocardial infarction

Background

Regular exercise training is an important factor in prevention of myocardial infarction (MI). However, little is known whether exercise engagement prior to MI is related to the magnitude of post-MI cardiac biomarker concentrations and clinical outcomes.

Objectives

We tested the hypothesis that exercise engagement in the week prior MI is related to lower cardiac biomarker concentrations following ST-elevated MI (STEMI).

Methods

We recruited hospitalised STEMI patients and assessed the amount of exercise engagement in the 7 days preceding MI onset using a validated questionnaire. Patients were classified as 'exercise' if they performed any vigorous exercise in the week prior MI, or as 'control' if they did not. Post-MI peak concentrations of high-sensitive cardiac troponin T (peak-hs-cTnT) and creatine kinase (peak-CK) were examined. We also explored whether exercise engagement prior MI is related to the clinical course (duration of hospitalisation and incidence of in-hospital, 30-day and 6-month major adverse cardiac events (reinfarction, target vessel revascularisation, cardiogenic shock or death)).

Results

In total, 98 STEMI patients were included, of which 16% (n=16) was classified as 'exercise', and 84% (n=82) as 'control'. Post-MI peak-hs-cTnT and peak-CK concentrations were lower in the exercise group (941 (645-2925) ng/mL; 477 (346-1402) U/L, respectively) compared with controls (3136 (1553-4969) ng/mL, p=0.010; 1055 (596-2019) U/L, p=0.016, respectively). During follow-up, no significant differences were found between both groups.

Conclusion

Engagement in exercise is associated with lower cardiac biomarker peak concentrations following STEMI. These data could provide further support for the cardiovascular health benefits of exercise training.

Blood flow modeling reveals improved collateral artery performance during the regenerative period in mammalian hearts

Collateral arteries bridge opposing artery branches, forming a natural bypass that can deliver blood flow downstream of an occlusion. Inducing coronary collateral arteries could treat cardiac ischemia, but more knowledge on their developmental mechanisms and functional capabilities is required. Here we used whole-organ imaging and three-dimensional computational fluid dynamics modeling to define spatial architecture and predict blood flow through collaterals in neonate and adult mouse hearts. Neonate collaterals were more numerous, larger in diameter and more effective at restoring blood flow. Decreased blood flow restoration in adults arose because during postnatal growth coronary arteries expanded by adding branches rather than increasing diameters, altering pressure distributions. In humans, adult hearts with total coronary occlusions averaged 2 large collaterals, with predicted moderate function, while normal fetal hearts showed over 40 collaterals, likely too small to be functionally relevant. Thus, we quantify the functional impact of collateral arteries during heart regeneration and repair-a critical step toward realizing their therapeutic potential.

Effect of Collateral Flow on Catheter-Based Assessment of Cardiac Microvascular Obstruction

Cardiac microvascular obstruction (MVO) associated with acute myocardial infarction (heart attack) is characterized by partial or complete elimination of perfusion in the myocardial microcirculation. A new catheter-based method (CoFI, Controlled Flow Infusion) has recently been developed to diagnose MVO in the catheterization laboratory during acute therapy of the heart attack. A porcine MVO model demonstrates that CoFI can accurately identify the increased hydraulic resistance of the affected microvascular bed. A benchtop microcirculation model was developed and tuned to reproduce in vivo MVO characteristics. The tuned benchtop model was then used to systematically study the effect of different levels of collateral flow. These experiments showed that measurements obtained in the catheter-based method were adversely affected such that collateral flow may be misinterpreted as MVO. Based on further analysis of the measured data, concepts to mitigate the adverse effects were formulated which allow discrimination between collateral flow and MVO.

Correlation of serum Vascular Endothelial growth factor (VEGF) and cardiovascular risk factors on collateral formation in patients with acute coronary artery syndrome

Coronary collaterals serve as an alternative source of blood flow in obstructive coronary heart disease. Coronary collateral development by releasing various angiogenic growth factors, including vascular endothelial growth factor-A (VEGF-A). Cardiovascular risk factors strongly associated with coronary artery disease include age, sex, elevated serum cholesterol, disturbed carbohydrate metabolism, and elevated blood pressure. A better understanding of the effects of these cardiovascular risk factors and serum VEGF-A level on collateral recruitment is necessary for a better prognosis in coronary artery diseases and new insight for further therapeutic promotion of coronary collaterals.220 consecutive patients undergoing coronary angiography with a mean age of 61 ± 9.83 were selected for the analysis. Two millilitres of blood were taken from the patients for analysis. The blood serum VEGF concentration was quantified via the ELISA method. Angiograms and other clinical reports were collected. Significant coronary artery disease was diagnosed in those with ≥ 70% of stenosis in at least one of the coronary arteries. The angiographic and clinical data were documented. The collateral grading was done according to the Rentrop Scoring system. The serum vascular endothelial growth factor level was correlated with the collateral score and cardiovascular risk factors like age, sex, type ll diabetes, blood pressure, and cholesterol level. An increase in the level of the collateral score was noted with an increase in the level of VEGF in blood serum. A significant association was founded between serum VEGF level and cardiovascular risk factors on collateral formation in patients with diabetes and hypertension. This article is protected by copyright. All rights reserved.

The prognostic value of the CHA2DS2-VASc score in coronary collateral circulation and long-term mortality in coronary artery disease

BACKGROUND

The CHA2DS2-VASc score is used to determine thromboembolic risk in cases of atrial fibrillation. The predictive value of this score in predicting coronary collateral circulation in chronic total occlusion is unknown.

OBJECTIVE

The aim of this study was to investigate the relationship between the CHA2DS2-VASc score and coronary collateral circulation in patients with chronic total occlusion.

METHODS

A total of 189 patients, who underwent coronary angiography and had a chronic total occlusion in at least one coronary artery, were enrolled in this study. The Rentrop scoring system was used for grouping the patients, and patients were classified as having poorly developed coronary collateral circulation (Rentrop grade 0 or 1) or well-developed coronary collateral circulation (Rentrop grade 2 or 3).

RESULTS

The CHA2DS2-VASc score of the good coronary collateral circulation group was significantly lower than the other group (3.1±1.7 vs. 3.7±1.7, p=0.021). During the follow-up period, 30 (32.2%) patients in the poorly developed coronary collateral circulation group and 16 (16.7%) patients in the well-developed coronary collateral circulation group died (p=0.028). According to the multivariable Cox regression model, the CHA2DS2-VASc score [hazard ratio (HR): 1.262, p=0.009], heart rate (HR: 1.049, p=0.003), LVEF (HR: 0.975, p=0.039), mean platelet volume (HR: 1.414, p=0.028), and not taking acetylsalicylic acid during admission (HR: 0.514, p=0.042) were independently associated with a higher risk of mortality.

CONCLUSIONS

The CHA2DS2-VASc score is closely related to coronary collateral development and predicts mortality in patients with chronic total occlusion.

The Effect of Long-Term External Counterpulsation Combined with Exercise Therapy on the Establishment of Collateral Circulation in Patients with Coronary Artery Occlusive Disease

Objective

By detecting the levels of external counterpulsation combined with exercise therapy on the levels of moesin, angiopoietin-like protein2 (Angptl 2), angiopoietin-like protein (Angptl 3), hypoxia inducible factor-1α (HIF-1α), and RNA-34a (miR-34a) in patients with coronary artery occlusive disease, the effect of external counterpulsation combined with exercise therapy on the establishment of occluded coronary collateral circulation was studied.

Methods

A retrospective analysis of 166 patients with coronary heart disease was confirmed by coronary angiography results that at least one coronary artery (anterior descending branch, circumflex branch, and right coronary artery) was completely occluded and was classified into the control group (routine medication) and the treatment group (routine drug therapy plus exercise therapy and external counterpulsation) according to the treatment plan of the patient. The serum levels of moesin, Angptl 2, Angptl 3, and HIF-1α were detected by enzyme-linked immunosorbent assay (ELISA) test. The index of microcirculatory resistance (IMR) and coronary flow reserve (CFR) of the two groups of patients were measured before and after 2 weeks of treatment. The formation of collateral circulation was analyzed according to the Rentrop classification method.

Results

After treatment, the IMR levels of the two groups were significantly decreased, and the CFR levels were significantly increased. The decrease of IMR level and the increase of CFR level in the experimental group were better than those in the control group (P < 0.05). There was no significant difference in the positive detection rate of moesin antibody between the two groups, but the OD detection value of the treatment group decreased significantly (P < 0.05). The levels of Angptl 2, Angptl 3, and miR-34a in the treatment group were lower than those in the control group, while the relative expression of HIF-1α was higher than that in the control group. The difference was statistically significant (P < 0.05). External counterpulsation combined with exercise therapy improved the formation rate of collateral circulation (P < 0.05).

Conclusions

External counterpulsation combined with exercise therapy can reduce moesin antibody, Angptl 2, Angptl 3, and miR-34a levels increase HIF-1α levels, and promote the establishment of occluded coronary collateral circulation.

The essential role for endothelial cell sprouting in coronary collateral growth

RATIONALE

Coronary collateral growth is a natural bypass for ischemic heart diseases. It offers tremendous therapeutic benefit, but the process of coronary collateral growth isincompletely understood due to limited preclinical murine models that would enable interrogation of its mechanisms and processes via genetic modification and lineage tracing. Understanding the processes by which coronary collaterals develop can unlock new therapeutic strategies for ischemic heart disease.

OBJECTIVE

To develop a murine model of coronary collateral growth by repetitive ischemia and investigate whether capillary endothelial cells could contribute to the coronary collateral formation in an adult mouse heart after repetitive ischemia by lineage tracing.

METHODS AND RESULTS

A murine model of coronary collateral growth was developed using short episodes of repetitive ischemia. Repetitive ischemia stimulation resulted in robust collateral growth in adult mouse hearts, validated by high-resolution micro-computed tomography. Repetitive ischemia-induced collateral formation compensated ischemia caused by occlusion of the left anterior descending artery. Cardiac function improved during ischemia after repetitive ischemia, suggesting the improvement of coronary blood flow. A capillary-specific Cre driver (Apln-CreER) was used for lineage tracing capillary endothelial cells. ROSA mT/mG reporter mice crossed with the Apln-CreER transgene mice underwent a 17 days' repetitive ischemia protocol for coronary collateral growth. Two-photon and confocal microscopy imaging of heart slices revealed repetitive ischemia-induced coronary collateral growth initiated from sprouting Apelin⁺ endothelial cells. Newly formed capillaries in the collateral-dependent zone expanded in diameter upon repetitive ischemia stimulation and arterialized with smooth muscle cell recruitment, forming mature coronary arteries. Notably, pre-existing coronary arteries and arterioles were not Apelin⁺, and all Apelin⁺ collaterals arose from sprouting capillaries. Cxcr4, Vegfr2, Jag1, Mcp1, and Hif1⍺ mRNA levels in the repetitive ischemia-induced hearts were also upregulated at the early stage of coronary collateral growth, suggesting angiogenic signaling pathways are activated for coronary collaterals formation during repetitive ischemia.

CONCLUSIONS

We developed a murine model of coronary collateral growth induced by repetitive ischemia. Our lineage tracing study shows that sprouting endothelial cells contribute to coronary collateral growth in adult mouse hearts. For the first time, sprouting angiogenesis is shown to give rise to mature coronary arteries in response to repetitive ischemia in the adult mouse hearts.

Modulating mitochondrial dynamics attenuates cardiac ischemia-reperfusion injury in prediabetic rats

Mitochondria are extraordinarily dynamic organelles that have a variety of morphologies, the status of which are controlled by the opposing processes of fission and fusion. Our recent study shows that inhibition of excessive mitochondrial fission by Drp1 inhibitor (Mdivi-1) leads to a reduction in infarct size and left ventricular (LV) dysfunction following cardiac ischemia-reperfusion (I/R) injury in high fat-fed induced pre-diabetic rats. In the present study, we investigated the cardioprotective effects of a mitochondrial fusion promoter (M1) and a combined treatment (M1 and Mdivi-1) in pre-diabetic rats. Wistar rats were given a high-fat diet for 12 weeks to induce prediabetes. The rats then subjected to 30 min-coronary occlusions followed by reperfusion for 120 min. These rats were intravenously administered M1 (2 mg/kg) or M1 (2 mg/kg) combined with Mdivi-1 (1.2 mg/kg) prior to ischemia, during ischemia or at the onset of reperfusion. We showed that administration of M1 alone or in combination with Mdivi-1 prior to ischemia, during ischemia or at the onset of reperfusion all significantly attenuated cardiac mitochondrial ROS production, membrane depolarization, swelling and dynamic imbalance, leading to reduced arrhythmias and infarct size, resulting in improved LV function in pre-diabetic rats. In conclusion, the promotion of mitochondrial fusion at any time-points during cardiac I/R injury attenuated cardiac mitochondrial dysfunction and dynamic imbalance, leading to decreased infarct size and improved LV function in pre-diabetic rats.

Traditional Cardiovascular Risk Factors and Coronary Collateral Circulation: A Meta-Analysis

Objective: Patients with well-developed coronary collateral circulation (CC) usually have low mortality, improved cardiac function, and reduced infarct size. Currently, there is conflicting evidence on the association between traditional cardiovascular risk factors (diabetes, hypertension, and smoking habit) and CC.

Design: We performed a meta-analysis of case-control studies to better understand such associations.

Data Sources: We searched the MEDINE, EMBASE, and Science Citation Index databases to identify relevant studies.

Eligibility Criteria for Selecting Studies: Case control studies reporting data on risk factors (smoking habit, hypertension, and diabetes mellites) in comparing cases between poor CC and well-developed CC groups. Well-developed CC was the primary outcome of this meta-analysis

Data Extraction and Synthesis: Relevant data were extracted by two independent investigators. We derived pooled odds ratios (ORs) with random effects models. We performed quality assessments, publication bias, and sensitivity analysis to ensure the reliability of our results.

Results: In total, 18 studies that had 4,746 enrolled patients were analyzed. Our results showed that hypertension and smoking habit did not (OR = 0.94, 95% CI: 0.75–1.17, p = 0.564 and OR = 1.00, 95% CI: 0.84–1.18, p = 0.970, respectively), and diabetes did (OR = 0.50, 95% CI: 0.38–0.67, p = 0.00001) affect the development of CC.

Conclusion: Unlike hypertension and smoking habit, diabetes was associated with poor CC formation.

Trial Registration Number:https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=87821, identifier: CRD42018087821.

Angiogenic effects of cell therapy within a biomaterial scaffold in a rat hind limb ischemia model

Critical limb ischemia (CLI) is a life- and limb-threatening condition affecting 1-10% of humans worldwide with peripheral arterial disease. Cellular therapies, such as bone marrow-derived mesenchymal stem cells (MSCs) have been used for the treatment of CLI. However, little information is available regarding the angiogenic potency of MSCs and mast cells (MC) in angiogenesis. The aim of this study was to evaluate the ability of MCs and MSCs to induce angiogenesis in a rat model of ischemic hind limb injury on a background of a tissue engineered hydrogel scaffold. Thirty rats were randomly divided into six control and experimental groups as follows: (a) Control healthy (b) Ischemic positive control with right femoral artery transection, (c) ischemia with hydrogel scaffold, (d) ischemia with hydrogel plus MSC, (e) ischemia with hydrogel plus MC and (f) ischemia with hydrogel plus MSC and MCs. 106 of each cell type, isolated from bone marrow stroma, was injected into the transected artery used to induce hind limb ischemia. The other hind limb served as a non-ischemic control. After 14 days, capillary density, vascular diameter, histomorphometry and immunohistochemistry at the transected location and in gastrocnemius muscles were evaluated. Capillary density and number of blood vessels in the region of the femoral artery transection in animals receiving MSCs and MCs was increased compared to control groups (P < 0.05). Generally the effect of MCs and MSCs was similar although the combined MC/MSC therapy resulted in a reduced, rather than enhanced, effect. In the gastrocnemius muscle, immunohistochemical and histomorphometric observation showed a great ratio of capillaries to muscle fibers in all the cell-receiving groups (P < 0.05). The data indicates that the combination of hydrogel and cell therapy generates a greater angiogenic potential at the ischemic site than cell therapy or hydrogels alone.

Intermittent appearance of right coronary fistula and collateral circulation: A case report

BACKGROUND

Congenital coronary artery fistula can lead to symptoms of chest tightness, chest pain, or exertional dyspnea, which is a congenital vascular malformation that should not be ignored. Patients who have such malformations are frequently observed with different concurrent abnormal anatomic structures. Collateral circulation may have a positive effect on improving the patients' symptoms.

CASE SUMMARY

A 53-year-old female experienced episodic chest discomfort for the past month with symptoms manifesting when she was agitated or overexerted. After a positive treadmill test, the patient underwent coronary angiography. “Ghostlike” intermittent appearance of coronary ventricular fistula and collateral branching were observed. The patient was diagnosed with a right coronary ventricular fistula and collateral circulation.

CONCLUSION

This case shows the likelihood of collateral circulation in patients with coronary artery fistula. This may provide medical staff with novel solutions to treat insufficiency of myocardial blood supply induced by cardiovascular malformations.

Non-high-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio serve as a predictor for coronary collateral circulation in chronic total occlusive patients

Objective

The present study investigated the potential correlation between non-high-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio (non-HDL-C/HDL) and the formation of coronary collateral circulation (CCC) in coronary artery disease cases with chronic total occlusive (CTO) lesions.

Methods

Two experienced cardiologists identified and selected patients with CTO lesions for retrospective analysis. The 353 patients were divided into a CCC poor formation group (Rentrop 0–1 grade, n = 209) and a CCC good formation group (Rentrop 2–3 grade, n = 144) based on the Cohen-Rentrop standard. A comparison of non-HDL-C/HDL ratios between the two groups was performed. The Spearman test was used to obtain the correlation between the cholesterol ratio and Rentrop grade. Independent predictors of CCC were analyzed using logistic regression. Receiver operating characteristic (ROC) curve analysis was also performed to quantify the predictive value of research indicator.

Results

The non-HDL-C/HDL ratio in the CCC poor formation group was elevated markedly compared to the CCC good formation group [( 3.86 ± 1.40) vs ( 3.31 ± 1.22), P = 0.000]. The Spearman test results indicated that non-HDL-C/HDL negatively correlated with Rentrop grade (r = − 0.115, P = 0.030). Multivariate logistic regression analysis showed that non-HDL-C/HDL ratio was an independent predictor of CCC formation (OR = 1.195, 95%CI = 1.020–1.400, P = 0.027). The area under the curve of ROC for detecting CCC poor formation was 0.611 (95% CI: 0.551–0.671, P = 0.000) with an optimal cut-off value of 2.77.

Conclusion

Non-HDL-C/HDL negatively correlated with the formation of CCC and served as an independent predictor of CCC formation, which may be used as a biomarker for the evaluation of CCC.

Contradictory Effect of Coronary Collateral Circulation on Regional Myocardial Perfusion That Assessed by Quantitative Myocardial Perfusion Scintigraphy

Background

Previous studies showed conflicting results about the contribution of coronary collateral circulation (CCC) to myocardial perfusion and function. The aim of this study was to investigate these contradictory problems by gated myocardial perfusion scintigraphy (gated MPS) for the first time.

Methods

The current cohort was retrospectively selected among patients who underwent gated MPS and coronary angiography within 2 months. Two different groups including 96 patients were assessed by gated MPS to detect the understanding of the miscellaneous effect of CCC on myocardial perfusion. Group 1 consisted of those who had collateral arteries that were not-well-developed (Rentrop grade 0 - 1) (n = 58), while group 2 consisted of those who had collateral arteries that were well-developed (Rentrop grade 2 - 3) (n = 38).

Results

There was no statistically significant difference between groups 1 and 2 in terms of perfusion and functional parameters obtained from gated MPS. Furthermore, no statistically significant difference was found in the phase analysis parameters which is a novel technique to evaluate left ventricular synchronization. On the other hand the left ventricular mass index values were high and quite close to the statistically significant value (P = 0.059) in group 2.

Conclusions

The current results that obtained by using the gated MPS technique for the first time in the evaluation of CCC showed that the well-developed collateral circulation has a positive effect on myocardial perfusion and function, but this effect was not statistically significant. Results need to be supported by large scale of patients’ size.

Cholesterol Efflux and Collateral Circulation in Chronic Total Coronary Occlusion: Effect-Circ Study

Background

The mechanism through which high‐density lipoprotein (HDL) induces cardioprotection is not completely understood. We evaluated the correlation between cholesterol efflux capacity (CEC), a functional parameter of HDL, and coronary collateral circulation (CCC). We additionally investigated whether A1BP (apoA1‐binding protein) concentration correlates with CEC and CCC.

Methods and Results

In this case‐control study, clinical and angiographic data were collected from 226 patients (mean age, 58 years; male, 72%) with chronic total coronary occlusion. CEC was assessed using a radioisotope and J774 cells, and human A1BP concentration was measured using enzyme‐linked immunosorbent assay. Differences between the good and poor CCC groups were compared, and associations between CEC, A1BP, and other variables were evaluated. Predictors of CCC were identified by multivariable logistic regression analysis. The CEC was higher in the good than in the poor CCC group (22.0±4.6% versus 20.2±4.7%; P=0.009). In multivariable analyses including age, sex, HDL‐cholesterol levels, age (odds ratio [OR], 0.96; P=0.003), and CEC (OR, 1.10; P=0.004) were identified as the independent predictors of good CCC. These relationships remained significant after additional adjustment for diabetes mellitus, acute coronary syndrome, and Gensini score. The A1BP levels were not significantly correlated with CCC (300 pg/mL and 283 pg/mL in the good CCC and poor CCC groups, respectively, P=0.25) or CEC.

Conclusions

The relationship between higher CEC and good CCC indicates that well‐functioning HDL may contribute to CCC and may be cardioprotective; this suggests that a specific function of HDL can have biological and clinical consequences.

Does the extent of collaterals influence the severity of the myocardial injury as assessed by elevation in biomarkers?

Introduction: Quantitative analysis of cardiac biomarkers, troponin I and CPK-MB, estimates the extent of myocardial injury while extent of benefit from coronary collateral circulation (CCC) to protect myocardium during acute myocardial infarction (AMI) needs validation. We analysed if the extent of collaterals had impact on baseline biomarkers at the time of coronary angiogram.

Methods: We analysed 3616 consecutive patients who presented with AMI and underwent invasive coronary angiography (CAG) with intent to revascularisation with biomarkers assessment at the time of CAG. CCC to Infarct related artery (IRA) were graded as per Rentrop grading viz. poorly-developed CCC (Grade 0/1 as Group A) and well-developed CCC (Grade 2/3 as Group B).

Results: Both groups (A and B) were matched for demographics, traditional risk factors, SYNTAX 1 Score, time to CAG from onset of angina and eGFR. 36.59% of patients had Non-ST segment elevation myocardial infarction (NSTEMI) as compared to 63.41% ST -segment elevation infarction (STEMI). Overall Troponin I (P =0.01, P =0.01) and CPK MB (P =0.00, P =0.002) values were lower in group B in both NSTEMI and STEMI groups respectively. Troponin I and CPK-MB were significantly lower in group B [with NSTEMI for SVD (Single vessel disease) (P =0.05) and DVD (Double vessel disease) (P =0.04),but not for TVD (Triple vessel disease) and with STEMI in SVD (P =0.01), DVD (P =0.01) and TVD (P =0.001)].

Conclusion: Patients with well-developed coronary collaterals had a lower rise in biomarkers in AMI as compared to those with poor collaterals amongst both NSTEMI and STEMI groups.

Visfatin and 25-Hydroxyvitamin D3 Levels Affect Coronary Collateral Circulation Development in Patients with Chronic Coronary Total Occlusion

Background: Coronary collateral circulation (CCC) plays a vital role in the myocardial blood supply, especially forischemic myocardium. Evidence suggests that the visfatin and 25-hydroxyvitamin D3 [25(OH)D3] levels are related to the degree and incidence of vascular stenosis associated with coronary artery disease; however, few studies have evaluated the effect of visfatin and 25(OH)D3 on CCC development in patients with chronic total occlusion (CTO).This study aimed to evaluate the relationship between the serum visfatin and 25(OH)D3 levels and CCC in patients with CTO.Methods: A total of 189 patients with CTO confirmed by coronary angiography were included. CCC was graded from 0 to 3 according to the Rentrop-Cohen classification. Patients with grade 0 or grade 1 collateral development were included in the poor CCC group (n = 82), whereas patients with grade 2 or grade 3 collateral development were included in the good CCC group (n = 107). The serum visfatin and 25(OH)D3 levels were measured by ELISA.Results: The visfatin level was significantly higher in the poor CCC group than in the good CCC group, and the 25(OH)D3 level was significantly lower in the poor CCC group than in the good CCC group (P = 0.000). Correlation analysis showed that the Rentrop grade was negatively correlated with the visfatin level (r = − 0.692, P = 0.000) but positively correlated with the 25(OH)D3 level (r = 0.635, P = 0.000). Logistic regression analysis showed that the visfatin and 25(OH)D3 levels were independent risk factors for CCC (odds ratio 1.597, 95% confidence interval 1.300–1.961, P = 0.000 and odds ratio 0.566, 95% confidence interval 0.444–0.722, P = 0.000, respectively). The visfatin and25(OH)D3 levels can effectively predict the CCC status.Conclusion: Serum visfatin and 25(OH)D3 levels are related to CCC development and are independent predictors of poor CCC.

Coronary remodeling and biomechanics: Are we going with the flow in 2020?

Under normal conditions, coronary blood flow (CBF) provides critical blood supply to the myocardium so that it can appropriately meet the metabolic demands of the body. Dogmatically, there exist several known regulators and modulators of CBF that include local metabolites and neurohormonal factors that can influence the function of the coronary circulation. In disease states such as diabetes and myocardial ischemia, these regulators are impaired or shifted such that CBF is reduced. Although functional considerations have been and continued to be well studied, more recent evidence builds upon established studies that collectively suggest that the relative roles of coronary structure, biomechanics, and the influence of cardiac biomechanics via extravascular compression may also play a significant role in dictating CBF. In this mini review, we discuss these regulators of CBF under normal and pathophysiological conditions and their potential influence on the control of CBF.

<p>Chronic Total Occlusion of the Left Main Coronary Artery in an HIV-Infected Patient</p>

Coronary artery disease (CAD) is amongst the leading causes of death in human immunodeficiency virus (HIV)-infected persons. Severe left main disease (LMD) occurs in approximately five percent of HIV-infected patients, with chronic total occlusion (CTO) of this vessel being an even rarer phenomenon. We describe a non-adherent HIV-infected patient with a left main coronary artery (LMCA) CTO that presented with heart failure with mildly reduced ejection fraction (HFrEF) and ventricular tachycardia (VT).

The study of myocardial ischemia-reperfusion treatment through computational modelling

Reperfusion of the blood flow to ischemic myocardium is the standard treatment for patients suffering myocardial infarction. However, the reperfusion itself can also induce myocardial injury, in which the actual mechanism and its risk factors remain unclear. This work aims to study the mechanism of ischemia-reperfusion treatment using a three-dimensional (3D) oxygen diffusion model. An electrical model is then coupled to an oxygen model to identify the possible region of myocardial damage. Our findings show that the value of oxygen exceeds its optimum (>1.0) at the ischemic area during early reperfusion period. This complication was exacerbated in a longer ischemic period. While a longer reperfusion time causes a continuous excessive oxygen supply to the ischemic area throughout the reperfusion time. This work also suggests the use of less than 0.8 of initial oxygen concentration in the reperfusion treatment to prevent undesired upsurge at the early reperfusion period and further myocardial injury. We also found the region at risk for myocardial injury is confined in the ischemic vicinity revealed by its electrical conductivity impairment. Although there is a risk that reperfusion leads to myocardial injury for excessive oxygen accumulation, the reperfusion treatment is helpful in reducing the infarct size.

Circulating CD34+VEGFR-2+ endothelial progenitor cells correlate with revascularization-mediated long-term improvement of cardiac function in patients with coronary chronic total occlusions

BACKGROUND

Endothelial progenitor cells (EPCs) participate in angiogenesis and neocollateralization. This study assessed if circulating EPCs can predict long-term improvement of global left ventricular systolic function in patients with coronary chronic total occlusions (CTOs) underwent successful percutaneous coronary intervention (PCI).

METHODS

In this single-center, prospective, observational study, 115 consecutive patients with CTOs were evaluated by standard transthoracic echocardiography (ECHO) before and 9-12 months after PCI. Numbers of circulating putative EPCs were determined by flow cytometry analysis of mononuclear cells isolated from peripheral blood samples drawn before and 72 h after PCI.

RESULTS

At mean 11.3 ± 2.5 months post vs. before PCI (all P < .05): by SAQ-7 summary scores, angina frequency, physical limitation and quality of life scores were greater; by ECHO, LVEDd decreased and LVEF increased, which were more significant in patients with Rentrop grades 2/3 vs. 0/1. At 72 h post vs. before PCI, CD34⁺VEGFR-2⁺CD133^- (0.82 ± 0.32 × 10⁶/L vs. 1.00 ± 0.39 × 10⁶/L, P = .003), CD34⁺VEGFR-2⁺CD133⁺ (0.24 ± 0.12 × 10⁶/L vs. 0.27 ± 0.14 × 10⁶/L, P = .028), and CD14⁺Tie2⁺VEGFR-2⁺ (6.60 ± 3.32 × 10⁶/L vs. 7.82 ± 3.91 × 10⁶/L, P = .006) cell numbers were lower. The baseline levels of CD34⁺VEGFR-2⁺cells (P = .001) and CD14⁺Tie2⁺VEGFR-2⁺cells (P < .001) were association with the grade of collateralization. In addition, the baseline and peri-procedural decrease of circulating CD34⁺VEGFR-2⁺ cells correlated with the increase of LVEF (P < .001, P < .001, respectively) and the decrease of LVEDd (P = .022, P = .029, respectively) at follow-up.

CONCLUSIONS

In this small study, the baseline levels of circulating CD34⁺VEGFR-2+ EPCs and its reduction after successful revascularization of CTOs correlated with long-term improvement in global LV systolic function.

Correlation between ischemia-modified albumin level and coronary collateral circulation

OBJECTIVE

To investigate the correlation between ischemia-modified albumin (IMA) levels and coronary collateral circulation (CCC) in patients with chronic total occlusive (CTO).

METHODS

Coronary angiography was performed in the Department of Cardiology, Zhongnan Hospital of Wuhan University from 2017 to 08 to 2019-02 to identify 128 patients with CTO lesions in at least one major coronary artery. According to the Rentrop evaluation criteria, the degree of CCC formation was divided into the poor CCC formation group (Rentrop0-1 grade,n = 69) and the good CCC formation group (Rentrop2-3 grade,n = 59). The IMA level of the patients was measured using an albumin-cobalt binding assay. The general data, routine blood panel, total bilirubin (TBIL), blood lipids, uric acid (UA), left ventricular ejection fraction (LVEF) and other indicators of the patients were recorded and analyzed while assessing the patients' blood vessel occlusion.

RESULTS

The proportion of platelet count and diabetes in the poor CCC group was higher than that in the good CCC group (P < 0.05). The ratio of ischemia-modified albumin and total bilirubin in the poor CCC group was lower than that in the good CCC group (P < 0.05). Multivariate logistic regression analysis showed that ischemia-modified albumin was positively correlated with CCC formation [OR = 1.190,95% CI (1.092-1.297),P < 0.001], while diabetes was negatively correlated with CCC formation [OR = 0.285,95% CI (0.094-0.864), P < 0.05]. Ischemic modified albumin predicted good formation of CCC according to the ROC curve, and the area under the ROC curve was 0.769(95% CI,0.686-0.851, P<0.001); the optimal cut-off value was 63.35 KU/L, and the sensitivity was 71.2%,specificity is 71%.

CONCLUSION

The IMA level is closely related to good formation of CCC. Higher IMA levels can be used as an effective predictor of good CCC formation in patients with CTO.

The Roles of AMPK in Revascularization

Coronary heart disease (CHD) is the most common and serious illness in the world and has been researched for many years. However, there are still no real effective ways to prevent and save patients with this disease. When patients present with myocardial infarction, the most important step is to recover ischemic prefusion, which usually is accomplished by coronary artery bypass surgery, coronary artery intervention (PCI), or coronary artery bypass grafting (CABG). These are invasive procedures, and patients with extensive lesions cannot tolerate surgery. It is, therefore, extremely urgent to search for a noninvasive way to save ischemic myocardium. After suffering from ischemia, cardiac or skeletal muscle can partly recover blood flow through angiogenesis (de novo capillary) induced by hypoxia, arteriogenesis, or collateral growth (opening and remodeling of arterioles) triggered by dramatical increase of fluid shear stress (FSS). Evidence has shown that both of them are regulated by various crossed pathways, such as hypoxia-related pathways, cellular metabolism remodeling, inflammatory cells invasion and infiltration, or hemodynamical changes within the vascular wall, but still they do not find effective target for regulating revascularization at present. 5′-Adenosine monophosphate-activated protein kinase (AMPK), as a kinase, is not only an energy modulator but also a sensor of cellular oxygen-reduction substances, and many researches have suggested that AMPK plays an essential role in revascularization but the mechanism is not completely understood. Usually, AMPK can be activated by ADP or AMP, upstream kinases or other cytokines, and pharmacological agents, and then it phosphorylates key molecules that are involved in energy metabolism, autophagy, anti-inflammation, oxidative stress, and aging process to keep cellular homeostasis and finally keeps cell normal activity and function. This review makes a summary on the subunits, activation and downstream targets of AMPK, the mechanism of revascularization, the effects of AMPK in endothelial cells, angiogenesis, and arteriogenesis along with some prospects.

The HEART score in the era of the European Society of Cardiology 0/1-hour algorithm

Background:

The European Society of Cardiology’s 0/1-hour algorithm improves the early triage of patients towards “rule-out” or “rule-in” of non-ST-segment elevation myocardial infarction. The HEART score is a risk stratification tool for patients with undifferentiated chest pain. We sought to evaluate the performance of the European Society of Cardiology 0/1-hour algorithm and the HEART score to evaluate chest pain patients in the emergency department.

Methods:

In this prospective study, we applied the European Society of Cardiology 0/1-hour algorithm and the HEART score in 1355 consecutive patients who presented to the emergency department with symptoms suggestive of acute coronary syndrome without ST-segment elevation. Patients were followed for non-ST-segment elevation myocardial infarctions and major adverse cardiac events at 30 days: death, non-ST-segment elevation myocardial infarction, or unplanned coronary revascularization.

Results:

The European Society of Cardiology 0/1-hour algorithm classified 921 (68.0%) patients as “rule-out” and the HEART score classified 686 (50.6%) patients as “low-risk”. The 30-day incidence of non-ST-segment elevation myocardial infarctions was 0.32% in the European Society of Cardiology 0/1-hour algorithm “rule-out” patients versus 0.29% in the HEART score “low-risk” patients ( p=0.75). The rate of major adverse cardiac events was 7.7% in the European Society of Cardiology 0/1-hour algorithm “rule-out” patients versus 1.1% in the HEART score “low-risk” patients ( p<0.001).

Conclusion:

The European Society of Cardiology 0/1-hour algorithm identified more patients with low risk of non-ST-segment elevation myocardial infarctions at 30 days whereas for major adverse cardiac events, the HEART score had a greater capacity to detect low-risk patients.

The dynamics of monocytes in the process of collateralization

Collateralization is an important way for patients with coronary heart disease to supply blood flow to the ischemic area. At present, research on the mechanism of collateral circulation mainly focuses on the inflammatory response. Monocytes are the kernel of inflammatory response during arteriogenesis. Therefore, we reviewed the recent developments in this field in terms of the dynamic changes of monocytes during collateralization. We searched and scanned PubMed for the following terms until November 2018: collateral, collateralization, monocyte, macrophage, and arteriogenesis. Articles were obtained and examined to figure out the dynamics of monocytes in the progress of collateralization. Substantial research shows that recruitment, infiltration, and phenotypic transformation of monocytes can affect function in various ways, respectively. Mechanical or chemical factors that can produce effects on collateral development may be due partly to impact on dynamics of monocytes. Although mechanisms of dynamics of monocytes during arteriogenesis are not elucidated clearly, there is no doubt that deeper exploration of the underlying mechanisms will contribute to pharmaceutical development aiming for promoting collateral development.

Cardioprotection during ischemia by coronary collateral growth

Ischemic heart diseases (IHD) cause millions of deaths around the world annually. While surgical and pharmacological interventions are commonly used to treat patients with IHD, their efficacy varies from patient to patient and is limited by the severity of the disease. One promising, at least theoretically, approach for treating IHD is induction of coronary collateral growth (CCG). Coronary collaterals are arteriole-to-arteriole anastomoses that can undergo expansion and remodeling in the setting of coronary disease when the disease elicits myocardial ischemia and creates a pressure difference across the collateral vessel that creates unidirectional flow. Well-developed collaterals can restore blood flow in the ischemic area of the myocardium and protect the myocardium at risk. Moreover, such collaterals are correlated to reduced mortality and infarct size and better cardiac function during occlusion of coronary arteries. Therefore, understanding the process of CCG is highly important as a potentially viable treatment of IHD. While there are several excellent review articles on this topic, this review will provide a unified overview of the various aspects related to CCG as well as an update of the advancements in the field. We also call for more detailed studies with an interdisciplinary approach to advance our knowledge of CCG. In this review, we will describe growth of coronary collaterals, the various factors that contribute to CCG, animal models used to study CCG, and the cardioprotective effects of coronary collaterals during ischemia. We will also discuss the impairment of CCG in metabolic syndrome and the therapeutic potentials of CCG in IHD.

Atypical presentation of critical left main disease in an HIV-infected patient

Coronary artery disease is currently one of the leading causes of mortality in patients with HIV. Severe left main disease (LMD) occurs in ~6% of the HIV-infected patients. We describe a case report of an atypical presentation of silent critical LMD in an HIV-infected patient who underwent a low-risk exercise stress test. The cardiovascular disease team should be vigilant for this latent phenomenon, specifically within this subpopulation despite the high Duke treadmill score.

Reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion

BACKGROUND

The extent of coronary collateral formation is a primary determinant of the severity of myocardial damage and mortality after coronary artery occlusion. Type 2 diabetes mellitus (T2DM) represents an important risk factor for impaired collateral vessel growth. However, the mechanism of reduced coronary collateralization in type 2 diabetic patients remains unclear.

METHODS

With the reference to the recent researches, this review article describes the pathogenic effects of T2DM on collateral development and outlines possible clinical and biochemical markers associated with reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion (CTO).

RESULTS

Diffuse coronary atherosclerosis in T2DM reduces pressure gradient between collateral donor artery and collateral recipient one, limiting collateral vessel growth and function. An interaction between advanced glycation end-products and their receptor activates several intracellular signaling pathways, enhances oxidative stress and aggravates inflammatory process. Diabetic condition decreases pro-angiogenic factors especially vascular endothelial growth factor and other collateral vessel growth related parameters. Numerous clinical and biochemical factors that could possibly attenuate the development of coronary collaterals have been reported. Increased serum levels of glycated albumin, cystatin C, and adipokine C1q tumor necrosis factor related protein 1 were associated with poor coronary collateralization in type 2 diabetic patients with stable coronary artery disease and CTO. Diastolic blood pressure and stenosis severity of the predominant collateral donor artery also play a role in coronary collateral formation.

CONCLUSIONS

T2DM impairs collateral vessel growth through multiple mechanisms involving arteriogenesis and angiogenesis, and coronary collateral formation in patients with T2DM and CTO is influenced by various clinical, biochemical and angiographic factors. This information provides insights into the understanding of coronary pathophysiology and searching for potential new therapeutic targets in T2DM.

Loss of c-Kit function impairs arteriogenesis in a mouse model of hindlimb ischemia

BACKGROUND

Arteriogenesis is a process whereby collateral vessels remodel usually in response to increased blood flow and/or wall stress. Remodeling of collaterals can function as a natural bypass to alleviate ischemia during arterial occlusion. Here we used a genetic approach to investigate possible roles of tyrosine receptor c-Kit in arteriogenesis.

METHODS

Mutant mice with loss of c-Kit function (Kit^W/W-v), and controls were subjected to hindlimb ischemia. Blood flow recovery was evaluated pre-, post-, and weekly after ischemia. Foot ischemic damage and function were assessed between days 1 to 14 post-ischemia while collaterals remodeling were measured 28 days post-ischemia. Both groups of mice also were subjected to wild type bone marrow cells transplantation 3 weeks before hindlimb ischemia to evaluate possible contributions of defective bone marrow c-Kit expression on vascular recovery.

RESULTS

Kit^W/W-v mice displayed impaired blood flow recovery, greater ischemic damage and foot dysfunction after ischemia compared to controls. Kit^W/W-v mice also demonstrated impaired collateral remodeling consistent with flow recovery findings. Because arteriogenesis is a biological process that involves bone marrow-derived cells, we investigated which source of c-Kit signaling (bone marrow or vascular) plays a major role in arteriogenesis. Kit^W/W-v mice transplanted with bone marrow wild type cells exhibited similar phenotype of impaired blood flow recovery, greater tissue ischemic damage and foot dysfunction as nontransplanted Kit^W/W-v mice.

CONCLUSION

This study provides evidence that c-Kit signaling is required during arteriogenesis. Also, it strongly suggests a vascular role for c-Kit signaling because rescue of systemic c-Kit activity by bone marrow transplantation did not augment the functional recovery of Kit^W/W-v mouse hindlimbs.

Translesional pressure gradient and leptomeningeal collateral status in symptomatic middle cerebral artery stenosis

BACKGROUND AND PURPOSE

Leptomeningeal collateral (LMC) status governs the prognosis of large artery occlusive stroke, although factors determining LMC status are not fully elucidated. The aim was to investigate metrics affecting LMC status in such patients by using computational fluid dynamics (CFD) models based on computed tomography angiography (CTA).

METHODS

In this cross-sectional study, patients with recent ischaemic stroke or transient ischaemic attack attributed to atherosclerotic M1 middle cerebral artery (MCA) stenosis (50%-99%) were recruited. Demographic, clinical and imaging data of these patients were collected. Ipsilesional LMC status was graded as good or poor by assessing the laterality of anterior and posterior cerebral arteries in CTA. A CFD model based on CTA was constructed to reflect focal hemodynamics in the distal internal carotid artery, M1 MCA and A1 anterior cerebral artery. Pressure gradients were calculated across culprit MCA stenotic lesions in CFD models. Predictors for good LMC status were sought in univariate and multivariate analyses.

RESULTS

Amongst the 85 patients enrolled (mean age 61.5 ± 10.9 years), 38 (44.7%) had good ipsilesional LMC status. The mean pressure gradient across MCA lesions was 14.8 ± 18.1 mmHg. Advanced age (P = 0.030) and a larger translesional pressure gradient (P = 0.029) independently predicted good LMCs. A lower fasting blood glucose level also showed a trend for good LMCs (P = 0.058).

CONCLUSIONS

Our study suggested a correlation between translesional pressure gradient and maturation of LMCs in intracranial atherosclerotic disease. Further studies with more exquisite and dynamic monitoring of cerebral hemodynamics and LMC evolution are needed to verify the current findings.

The role of coronary artery collaterals in the preservation of left ventricular function: a study to address a long-standing controversy

Introduction:

The functional significance of coronary artery collateral (CAC) vasculature in humans has been debated for decades and this has been compounded by the lack of a standard, systematic, objective method of grading and documenting CAC flow in man. CACs serve as alternative conduits for blood in obstructive coronary artery disease. This study aimed to evaluate the impact of CACs on left ventricular function in the presence of total coronary arterial occlusion.

Methods:

The study group included the coronary angiographic records of 97 patients (mean age: 59 ± 8 years). CACs were graded from 0–3 based on the collateral connection between the donor and recipient arteries. Left ventricular function was computed from the ventriculogram and expressed as ejection fraction (EF).

Results:

The mean EF of the patients with grades 0, 1, 2 and 3 CACs were calculated as 50.4, 47, 60.5 and 70%, respectively. A significant difference was recorded in the mean EF calculated for the different CAC grades (p = 0.001). There was a significant positive correlation (p < 0.001; r = 0.478) between the mean EF and the CAC grades.

Conclusion:

The patients with better coronary collateral grades had a higher mean EF. Therefore, as the grade of CACs increased, there was an improvement in their ability to preserve left ventricular function.

MiR-15b-5p Regulates Collateral Artery Formation by Targeting AKT3 (Protein Kinase B-3)

OBJECTIVE

To identify circulating microRNAs that are differentially expressed in severe coronary heart disease with well or poorly developed collateral arteries and to investigate their mechanisms of action in vivo and in vitro.

APPROACH AND RESULTS

In our study, we identified a circulating microRNA, miR-15b-5p, with low expression that, nevertheless, characterized patients with sufficient coronary collateral artery function. Moreover, in murine hindlimb ischemia model, in situ hybridization identified that miR-15b-5p was specifically expressed in vascular endothelial cells of adductors in sham group and was remarkably downregulated after femoral artery ligation. Overexpressed miR-15b-5p significantly inhibited arteriogenesis and angiogenesis in mice. In vitro, both under basal and vascular endothelial growth factor stimulation, loss-of-function or gain-of-function studies suggested that miR-15b-5p significantly promoted or depressed the migration and proliferation of endothelial cells. We identified AKT3 (protein kinase B-3) as a direct target of miR-15b-5p. Interestingly, AKT3 deficiency by injection with Chol-AKT3-siRNA obviously suppressed arteriogenesis and the recovery of blood perfusion after femoral ligation in mice.

CONCLUSIONS

These results indicate that circulating miR-15b-5p is a suitable biomarker for discriminating between patients with well-developed or poorly developed collaterals. Moreover, miR-15b-5p is a key regulator of arteriogenesis and angiogenesis, which may represent a potential therapeutic target for ischemic disease.

Plasma Omentin-1 Level as a Predictor of Good Coronary Collateral Circulation

Aims: Coronary collateral circulation (CCC) is crucial during an acute ischemic attack. Evidences showed that omentin-1 exhibited remarkable antiatherogenic effects and ischemia-induced revascularization. The aim of this study was to investigate the relationship between plasma omentin-1 levels and CCC in patients with ≥ 90% angiography-proven coronary occlusion.

Methods: 142 patients with ≥ 90% luminal diameter stenosis in at least one major epicardial coronary artery were recruited. Among them, 79 patients with Rentrop 0–1 grade were classified into the poor CCC group and 63 patients with Rentrop 2–3 grade were included into the good CCC group. The association between plasma omentin-1 levels and CCC status was assessed.

Results: Plasma omentin-1 level was significantly higher in patients with good CCC than those with poor CCC (566.57 ± 26.90 vs. 492.38 ± 19.70 ng/mL, p = 0.024). Besides, omentin-1 was positively correlated with total cholesterol (TC), high-density lipoprotein, and gensini score but inversely with hyperlipidemia and body mass index (all p values < 0.05). Multivariate regression analysis indicated that omentin-1 [odds ratio (OR) = 1.002, 95% confidence interval (CI): 1.000 – 1.004, p = 0.041)], TC, the number of the diseased vessels, a higher frequency of left circumflex artery and right coronary artery, chronic total occlusion, and gensini score remained as the independent predictors of good CCC.

Conclusion: Higher plasma omentin-1 level was associated with better CCC development. Our findings suggest that omentin-1 may be an alternative marker for adequate CCC in patients with ≥ 90% coronary occlusion.

Cyanate-Impaired Angiogenesis: Association With Poor Coronary Collateral Growth in Patients With Stable Angina and Chronic Total Occlusion

Background

Cyanate has recently gained attention for its role in the pathogenesis of vascular injury. Nonetheless, the effect of cyanate on angiogenesis remains unclear.

Methods and Results

In this study, we demonstrated that oral administration of cyanate impaired blood perfusion recovery in a mouse hind‐limb ischemia model. A reduction in blood perfusion recovery at day 21 was observed in the ischemic tissue of cyanate‐treated mice. Likewise, there were fewer capillaries in the ischemic hind‐limb tissue of cyanate‐exposed mice. Our in vitro study showed that cyanate, together with its carbamylated products, inhibited the migration, proliferation, and tube‐formation abilities of endothelial cells. Further research revealed that cyanate regulated angiogenesis partly by interrupting the vascular endothelial growth factor receptor 2/phosphatidylinositol 3‐kinase/Akt pathway. The serum concentrations of homocitrulline, a marker of cyanate exposure, were determined in 117 patients with stable angina and chronic total occlusion. Consistent with the antiangiogenic role of cyanate, homocitrulline levels were increased in patients with poor coronary collateralization (n=58) compared with those with high collateralization (n=59; 21.09±13.08 versus 15.54±9.02 ng/mL, P=0.009). In addition, elevated homocitrulline concentration was a strong predictor of poor coronary collateral growth.

Conclusions

Impaired angiogenesis induced by cyanate might contribute to poor coronary collateral growth.

Low-Dose Lithium Stabilizes Human Endothelial Barrier by Decreasing MLC Phosphorylation and Universally Augments Cholinergic Vasorelaxation Capacity in a Direct Manner

Lithium at serum concentrations up to 1 mmol/L has been used in patients suffering from bipolar disorder for decades and has recently been shown to reduce the risk for ischemic stroke in these patients. The risk for stroke and thromboembolism depend not only on cerebral but also on general endothelial function and health; the entire endothelium as an organ is therefore pathophysiologically relevant. Regardless, the knowledge about the direct impact of lithium on endothelial function remains poor. We conducted an experimental study using lithium as pharmacologic pretreatment for murine, porcine and human vascular endothelium. We predominantly investigated endothelial vasorelaxation capacities in addition to human basal and dynamic (thrombin-/PAR-1 receptor agonist-impaired) barrier functioning including myosin light chain (MLC) phosphorylation (MLC-P). Low-dose therapeutic lithium concentrations (0.4 mmol/L) significantly augment the cholinergic endothelium-dependent vasorelaxation capacities of cerebral and thoracic arteries, independently of central and autonomic nerve system influences. Similar concentrations of lithium (0.2–0.4 mmol/L) significantly stabilized the dynamic thrombin-induced and PAR-1 receptor agonist-induced permeability of human endothelium, while even the basal permeability appeared to be stabilized. The lithium-attenuated dynamic permeability was mediated by a reduced endothelial MLC-P known to be followed by a lessening of endothelial cell contraction and paracellular gap formation. The well-known lithium-associated inhibition of inositol monophosphatase/glycogen synthase kinase-3-β signaling-pathways involving intracellular calcium concentrations in neurons seems to similarly occur in endothelial cells, too, but with different down-stream effects such as MLC-P reduction. This is the first study discovering low-dose lithium as a drug directly stabilizing human endothelium and ubiquitously augmenting cholinergic endothelium-mediated vasorelaxation. Our findings have translational and potentially clinical impact on cardiovascular and cerebrovascular disease associated with inflammation explaining why lithium can reduce, e.g., the risk for stroke. However, further clinical studies are warranted.

Relationship between thrombospondin-1, endostatin, angiopoietin-2, and coronary collateral development in patients with chronic total occlusion

This study is aimed to investigate whether serum angiostatic factors (thrombospondin-1 [TSP-1] and endostatin) or angiogenic factors (angiopoietin-2 [Ang-2]) are related to coronary collateral vessel development in patients with chronic total occlusion (CTO).A total of 149 patients were enrolled in the study, and 39 patients with coronary artery disease but without significant stenosis were included in control group. In 110 patients with CTO lesion, 79 with Rentrop grades 2 to 3 collaterals were grouped as good collateral, while 31 with Rentrop grades 0 to 1 collaterals were grouped as poor collateral. Serum TSP-1, endostatin, and Ang-2 levels were studied.Serum endostatin level was significantly higher in poor collateral group compared with control group and good collateral group, respectively (96.2 ± 30.4 vs 77.8 ± 16.5 ng/mL, P = 0.007; 96.2 ± 30.4 vs 81.2 ± 30.4 ng/mL, P = 0.018). In multivariate analysis, decreased serum endostatin level was independently related to good coronary collateral development. Serum TSP-1 level was lower in patients with CTO compared with control group. However, no difference in TSP-1 level was detected between poor and good collateral group. The serum Ang-2 level did not show a significant difference among 3 groups.Circulatory endostatin may be a useful biomarker for coronary collateral development and potential target for therapeutic angiogenesis in patients with CTO.

Endothelial-Specific EphA4 Negatively Regulates Native Pial Collateral Formation and Re-Perfusion following Hindlimb Ischemia

Leptomeningeal anastomoses play a critical role in regulating vascular re-perfusion following obstruction, however, the mechanisms regulating their development remains under investingation. Our current findings indicate that EphA4 receptor is a novel negative regulator of collaterogenesis. We demonstrate that EphA4 is highly expressed on pial arteriole collaterals at post-natal day (P) 1 and 7, then significantly reduced by P21. Endothelial cell (EC)-specific loss of EphA4, EphA4f/f/Tie2::Cre (KO), resulted in an increase in the density but not diameter of pial collaterals compared to WT mice. ECs isolated from KO mice displayed a 3-fold increase in proliferation, enhanced migration, tube formation and elevated levels of phospho(p)-Akt compared to WT ECs. Attenuating p-Akt, using LY294002, reduced the proliferative and migration effects in the KO ECs. RNAseq analysis also revealed altered expression patterns for genes that regulate cell proliferation, vascular development, extracellular matrix and immune-mediate responses, namely MCP-1, MMP2 and angiopoietin-1. Lastly, we show that induction of hindlimb ischemia resulted in accelerated re-perfusion, collateral remodeling and reduced tissue necrosis in the absence of EC-specific EphA4 compared to WT mice. These findings demonstrate a novel role for EphA4 in the early development of the pial collateral network and suggests a role in regulating vascular remodeling after obstruction.

The challenge of translating ischemic conditioning from animal models to humans: the role of comorbidities

Following a period of ischemia (local restriction of blood supply to a tissue), the restoration of blood supply to the affected area causes significant tissue damage. This is known as ischemia-reperfusion injury (IRI) and is a central pathological mechanism contributing to many common disease states. The medical complications caused by IRI in individuals with cerebrovascular or heart disease are a leading cause of death in developed countries. IRI is also of crucial importance in fields as diverse as solid organ transplantation, acute kidney injury and following major surgery, where post-operative organ dysfunction is a major cause of morbidity and mortality. Given its clinical impact, novel interventions are urgently needed to minimize the effects of IRI, not least to save lives but also to reduce healthcare costs. In this Review, we examine the experimental technique of ischemic conditioning, which entails exposing organs or tissues to brief sub-lethal episodes of ischemia and reperfusion, before, during or after a lethal ischemic insult. This approach has been found to confer profound tissue protection against IRI. We discuss the translation of ischemic conditioning strategies from bench to bedside, and highlight where transition into human clinical studies has been less successful than in animal models, reviewing potential reasons for this. We explore the challenges that preclude more extensive clinical translation of these strategies and emphasize the role that underlying comorbidities have in altering the efficacy of these strategies in improving patient outcomes.

Epicardial adipose tissue is related to coronary collateral vessel formation in patients with acute coronary syndrome

OBJECTIVES

Epicardial adipose tissue (EAT) is the ectopic fat surrounding the heart, and it may contribute to coronary collateral vessel (CCV) formation. We aimed to evaluate the association of EAT with the presence of CCV in patients with acute coronary syndrome (ACS).

DESIGN

A total of 230 patients with ACS were included. The CCVs were graded according to the Rentrop scoring system, and a Rentrop grade 0-1 was accepted as low-grade CCV group, Rentrop grade 2-3 was accepted as high-grade CCV group.

RESULTS

According to angiography, 70 (30%) patients constituted the high-grade CCV group and 160 (70%) constituted the low-grade CCV group. The high-grade CCV group had thicker EAT than the low-grade CCV group (6.1 ± 1.4 vs. 5.3 ± 1.4 mm; p = 0.001). Multivariate logistic regression analysis showed that presence of CCV was independently associated with EAT thickness, ejection fraction, presenting with ST-segment elevation myocardial infarction, and presence of angina on admission. EAT thickness of > 5.7 mm can independently predict high-grade CCV with 73% sensitivity and 69% specificity (area under the curve or AUC: 0.65; 95% confidence interval or CI: 0.57-0.72).

CONCLUSIONS

EAT thickness on admission was associated with the presence of CCVs in patients with ACS.

Coronary Collateral Circulation and Cardiovascular Risk Factors: Is There a Paradox?

We sought to determine the association of major cardiovascular risk factors and other comorbidities with the presence or absence of coronary collateral (CC) circulation. All electronic medical records from 2010 to 2011 were retrospectively reviewed. A total of 563 patients were divided into 2 groups: CC present (180) and CC absent (383). Smoking (P = .012, odds ratio [OR] 1.58), hypercholesterolemia (P = .001, OR 2.21), and hypertension (P = .034, OR 1.75) were associated with the presence of CC. Increasing body mass index (BMI, P = .001) and decreasing estimated glomerular filtration rate (eGFR, P = .042) were associated with the absence of CC. On multivariable linear regression analysis, hypercholesterolemia (P = .001, OR 2.28), BMI (P = .012, OR 0.77), and eGFR (P = .001, OR 0.70) were found to be independently associated with CC. Our findings will help predict patient populations more likely to have presence or absence of CC circulation.