Effects of Aging on the Collateral Circulation, and Therapeutic Implications

Assessing different brain oxygenation components in elderly patients under propofol or sevoflurane anesthesia: A randomized controlled study

STUDY OBJECTIVE

Elderly patients undergoing pathophysiological changes necessitate clinical tools for cerebral monitoring. This prospective randomized controlled study aimed to explore how cerebral monitoring using Δo2Hbi, ΔHHbi, and ΔcHbi manifests in elderly patients under either propofol or sevoflurane anesthesia.

DESIGN

Single-center, prospective, randomization.

SETTING

A single tertiary hospital (Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea).

PATIENTS

Enrolled 100 patients scheduled for urologic surgery under general anesthesia. Inclusion criteria were (a) age 70-80 years, (b) American Society of Anesthesiologists (ASA) physical status I-II.

INTERVENTION

Patients were double-blind randomized to receive propofol-based or sevoflurane anesthesia. Cerebral oximetry-related parameters were measured at 5, 10, 15, 20, and 30 min in a setting devoid of surgery-related factors.

MEASUREMENTS

The primary outcome focused on the Δo2Hbi pattern in the left and right sides within the propofol and sevoflurane groups.

MAIN RESULTS

We analyzed 100 patients, 50 patients in each group. In the propofol group, the left Δo2Hbi decreased from 1.4 (3.7) at 5 min to -0.1 (1.8) at 30 min (P < 0.0001), and the right Δo2Hbi decreased from 2.9 (4.2) at 5 min to -0.06 (2.3) at 30 min (P < 0.0001). In the sevoflurane group, the left Δo2Hbi decreased from 1.1 (3.4) at 5 min to -1.4 (4.4) at 30 min (P < 0.0001), and the right Δo2Hbi decreased from 2.0 (3.2) at 5 min to -1.2 (3.9) at 30 min (P < 0.0001). There were no significant differences between the two groups. ΔHHbi did not exhibit significant changes after an initial decrease at 5 min and showed no significant differences between the two groups.

CONCLUSIONS

In cerebral oximetry, Δo2Hbi and ΔHHbi could emerge as a valuable approach for discerning changes in the underlying baseline status of the brain in elderly patients during anesthesia.

Impaired post-stroke collateral circulation in sickle cell anemia mice

Patients with sickle cell anemia (SCA) have a high incidence of ischemic stroke, but are usually excluded from thrombolytic therapy due to concerns for cerebral hemorrhage. Maladaptation to cerebral ischemia may also contribute to the stroke propensity in SCA. Here we compared post-stroke cortical collateral circulation in transgenic sickle (SS) mice, bone marrow grafting-derived SS-chimera, and wildtype (AA) controls, because collateral circulation is a critical factor for cell survival within the ischemic penumbra. Further, it has been shown that SS mice develop poorer neo-collateral perfusion after limb ischemia. We used the middle cerebral artery (MCA)-targeted photothrombosis model in this study, since it is better tolerated by SS mice and creates a clear infarct core versus peri-infarct area. Compared to AA mice, SS mice showed enlarged infarction and lesser endothelial proliferation after photothrombosis. SS-chimera showed anemia, hypoxia-induced erythrocyte sickling, and attenuated recovery of blood flow in the ipsilateral cortex after photothrombosis. In AA chimera, cerebral blood flow in the border area between MCA and the anterior cerebral artery (ACA) and posterior cerebral artery (PCA) trees improved from 44% of contralateral level after stroke to 78% at 7 d recovery. In contrast, blood flow in the MCA-ACA and MCA-PCA border areas only increased from 35 to 43% at 7 d post-stroke in SS chimera. These findings suggest deficits of post-stroke collateral circulation in SCA. Better understanding of the underpinnings may suggest novel stroke therapies for SCA 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.

Identifying 'fast progressors' likely to benefit from mechanical thrombectomy

OBJECTIVES

Although the effect of mechanical thrombectomy in large vessel occlusions has been clearly demonstrated, there are different opinions about the treatment of patients with low ASPECT scores. We conducted this research to explore the utility of mechanical thrombectomy for the fast progressor patients.

METHODS

We evaluated 394 patients with large vessel occlusion (LVO) who applied to our center between 2012 and 2020 retrospectively. Patients with posterior system stroke and who admitted 6 h after the onset of symptoms, were not included in the study. The remaining 256 patients were divided into two groups as computed tomography angiography source image Alberta stroke program early computer tomography score (CTA-SI ASPECT) ≤ 6 and > 6. Modified rankin scale (mRS) 0-2 defined as good clinical outcome. Thrombolysis in cerebral infarction (TICI) score 2c-3 was accepted as successful recanalization.

RESULTS

The mean age of the patients in the fast-progressive group (23.4%; n = 60) was 66.3 ± 11.6 years, whereas the mean age of the CTA-SI ASPECTS > 6 group (76.6%; n = 196) was 62.4 ± 12.8 years (p = 0.034) A statistically significant difference was found between the groups regarding 90-day mRS (p < 0.001). Whereas 61.7% of the patients with a CTA-SI ASPECTS > 6 had a 90-day mRS 0-2, this rate was 28.3% for patients with a CTA-SI ASPECTS ≤ 6.

CONCLUSION

According to our study, approximately 1/3 of patients with ASPECTS ≤ 6 benefit from mechanical thrombectomy. In this patient group, age emerged as a determinant of good clinical outcome.

Age-Related Utilization of Thrombus Aspiration in Patients With ST-Segment Elevation Myocardial Infarction: Findings From the Improving Care for Cardiovascular Disease in China Project

Background

There are some controversies on the utilization and benefits of thrombus aspiration in patients with ST-segment elevation myocardial infarction (STEMI). However, a few studies investigated this issue and the age-associated effects among the large population in China. Hence, we aimed to figure out the age-associated utilization and in-hospital outcomes of thrombus aspiration to improve therapeutic decisions in clinical routine.

Methods

We retrospectively recruited 13,655 eligible STEMI patients from the database of the Improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome project. These subjects were allocated into primary percutaneous coronary intervention (PPCI)-only group and thrombus aspiration group after being subdivided into three age groups (G21−50, G51−75, and G76−95). After 1:1 propensity score matching for PPCI-only and thrombus aspiration groups, a total of 8,815 matched patients were enrolled for the subsequent analysis. The primary outcome was in-hospital cardiovascular death, and the key safety outcome was in-hospital stroke.

Results

We observed that the ratio of STEMI patients undergoing thrombus aspiration to PPCI-only reduced with aging. For patients ≤ 75 years, the culprit lesion suffered from thrombus aspiration was mainly located in the left anterior descending branch, and left-ventricular ejection fraction (LVEF) was lower (G21−50: 54.9 ± 8.9 vs. 56.0 ± 8.7%, P = 0.01; G51−75: 53.9 ± 9.6 vs. 54.8 ± 9.0%, P = 0.001) and the rate of regional wall motion abnormality was higher (G21−50: 75.7 vs. 66.5%, P &lt; 0.001; G51−75: 75.4 vs. 69.1%, P &lt; 0.001) in the thrombus aspiration group. By contrast, for patients &gt; 75 years, the right coronary artery was the predominant culprit lesion undergoing thrombus aspiration, LVEF (63.1 ± 10.5 vs. 53.1 ± 9.5%, P = 0.985) and the regional wall motion abnormality (79.2 vs. 74.2%, P = 0.089) were comparable between the two treatment groups. Thrombus aspiration neither reduced the in-hospital risk of cardiovascular death, all-cause death, recurrent myocardial infarction, acute stent thrombosis, heart failure, cardiogenic shock, and sudden cardiac arrest nor increased stroke risk compared with the PPCI-only group. However, after adjustment for age, thrombus aspiration presented the tendency to reduce the incidence of sudden cardiac arrest (4.9 vs. 2.5%, P = 0.06) and in-hospital cardiovascular death at 3 days (hazard ratio 0.46; 95% CI, 0.20–1.06; log-rank P = 0.08) in G76−95 group and tended to increase the incidence of heart failure in G51−75 (5.7 vs. 6.9%, P = 0.07).

Conclusion

The thrombus aspiration neither significantly reduced the in-hospital incidence of major adverse cardiac events nor increased stroke risk. However, it might play a protective role in reducing in-hospital sudden cardiac arrest and increasing survival from cardiovascular death at 3 days for the elderly.

Association between the triglyceride glucose index and coronary collateralization in coronary artery disease patients with chronic total occlusion lesions

Background

Recent studies have substantiated the role of the triglyceride glucose (TyG) index in predicting the prognosis of coronary artery disease (CAD) patients, while no relevant studies have revealed the association between the TyG index and coronary collateralization in the event of coronary chronic total occlusion (CTO). The current study intends to explore whether, or to what extent, the TyG index is associated with impaired collateralization in CAD patients with CTO lesions.

Methods

The study enrolled 1093 CAD patients undergoing cardiac catheterization for at least one CTO lesion. Data were collected from the Beijing Anzhen Hospital record system. The degree of collaterals was determined according to the Rentrop classification system. The correlation between the TyG index and coronary collateralization was assessed.

Results

Overall, 318 patients were included in a less developed collateralization (Rentrop classification 0-1) group. The TyG index was significantly higher in patients with impaired collateralization (9.3±0.65 vs. 8.8±0.53, P<0.001). After adjusting for various confounding factors, the TyG index remained correlated with the occurrence of impaired collateralization, with odds ratios (ORs) of 1.59 and 5.72 in the T2 and T3 group compared with the first tertile group (P<0.001). In addition, subgroup analysis showed that higher TyG index values remained strongly associated with increased risk of less developed collateralization. To compare the risk assessment efficacy for the formation of collateralization between the TyG index and other metabolic abnormality indicators, an area under the receiver-operating characteristic (ROC) curve (AUC) was obtained. A significant improvement in the risk assessment performance for impaired collateralization emerged when adding the TyG index into a baseline model.

Conclusions

The increased TyG index is strongly associated with less developed collateralization in CAD patients with CTO lesions and its risk assessment performance is better than single metabolic abnormality indicators.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01574-x.

The association of interferon-alpha with development of collateral circulation after artery occlusion

Background

Previous studies have demonstrated that interferon (IFN) signaling is enhanced in patients with poor collateral circulation (CC). However, the role and mechanisms of IFN‐alpha in the development of CC remain unknown.

Methods

We studied the serum levels of IFN‐alpha and coronary CC in a case–control study using logistics regression, including 114 coronary chronic total occlusion (CTO) patients with good coronary CC and 94 CTO patients with poor coronary CC. Restricted cubic splines was used to flexibly model the association of the levels of IFN‐alpha with the incidence of good CC perfusion restoration after systemic treatment with IFN‐alpha was assessed in a mice hind‐limb ischemia model.

Results

Compared with the first IFN‐alpha tertile, the risk of poor CC was higher in the third IFN‐alpha tertile (OR: 4.79, 95% CI: 2.22–10.4, p < .001). A cubic spline‐smoothing curve showed that the risk of poor CC increased with increasing levels of serum IFN‐alpha. IFN‐alpha inhibited the development of CC in a hindlimb ischemia model. Arterioles of CC in the IFN‐alpha group were smaller in diameter than in the control group.

Conclusion

Patients with CTO and with poor CC have higher serum levels of IFN‐alpha than CTO patients with good CC. IFN‐alpha might impair the development of CC after artery occlusion.

Determinants of Leptomeningeal Collateral Status Variability in Ischemic Stroke Patients

BACKGROUND

Collateral status is an indicator of a favorable outcome in stroke. Leptomeningeal collaterals provide alternative routes for brain perfusion following an arterial occlusion or flow-limiting stenosis. Using a large cohort of ischemic stroke patients, we examined the relative contribution of various demographic, laboratory, and clinical variables in explaining variability in collateral status.

METHODS

Patients with acute ischemic stroke in the anterior circulation were enrolled in a multi-center hospital-based observational study. Intracranial occlusions and collateral status were identified and graded using multiphase computed tomography angiography. Based on the percentage of affected territory filled by collateral supply, collaterals were graded as either poor (0-49%), good (50-99%), or optimal (100%). Between-group differences in demographic, laboratory, and clinical factors were explored using ordinal regression models. Further, we explored the contribution of measured variables in explaining variance in collateral status.

RESULTS

386 patients with collateral status classified as poor (n = 64), good (n = 125), and optimal (n = 197) were included. Median time from symptom onset to CT was 120 (IQR: 78-246) minutes. In final multivariable model, male sex (OR 1.9, 95% CIs [1.2, 2.9], p = 0.005) and leukocytosis (OR 1.1, 95% CIs [1.1, 1.2], p = 0.001) were associated with poor collaterals. Measured variables only explained 44.8-53.0% of the observed between-patient variance in collaterals.

CONCLUSION

Male sex and leukocytosis are associated with poorer collaterals. Nearly half of the variance in collateral flow remains unexplained and could be in part due to genetic differences.

Association between short-term exposure to ambient fine particulate matter and myocardial injury in the CATHGEN cohort

Exposure to fine particulate matter (PM_2.5) has been associated with a higher risk for coronary events. Elevated circulating cardiac troponins (cTn) are suggestive of myocardial injury in both ischemic and non-ischemic conditions. However, little is known about the association between PM_2.5 and cTn. In this study, we investigated short-term PM_2.5 effects on cardiac troponin T (cTnT), as well as N-terminal-pro brain natriuretic peptide (NT-pro BNP) and inflammatory biomarkers among cardiac catheterized participants. We analyzed 7444 plasma cTnT measurements in 2732 participants who presented to Duke University Hospital with myocardial infarction symptoms between 2001 and 2012, partly along with measurements of NT-pro BNP and inflammatory biomarkers. Daily PM_2.5 concentrations were predicted by a neural network-based hybrid model and were assigned to participants' residential addresses. We applied generalized estimating equations to assess associations of PM_2.5 with biomarker levels and the risk of a positive cTnT test (cTnT > 0.1 ng/mL). The median plasma cTnT concentration at presentation was 0.05 ng/mL and the prevalence of a positive cTnT test was 35.4%. For an interquartile range (7.6 μg/m³) increase in PM_2.5 on the previous day, cTnT concentrations increased by 7.7% (95% CI: 3.4-12.3) and the odds ratio of a positive cTnT test was 1.08 (1.01-1.16). Participants under 60 years (effect estimate: 15.2%; 95% CI: 7.4-23.5) or living in rural areas (12.3%; 95% CI: 4.8-20.3) were more susceptible. There was evidence for increases in fibrinogen and NT-pro BNP associated with elevated PM_2.5 on the concurrent and previous two days. Our study suggests that acute PM_2.5 exposure may elevate indicators of myocardial tissue damage. This finding substantiates the association of air pollution exposure with adverse cardiovascular events.

Effect of Recruitment of Acute Coronary Collaterals on In-Hospital Mortality and on Left Ventricular Function in Patients Presenting With ST Elevation Myocardial Infarction

Recruitment of the coronary collateral circulation is frequently observed during ST elevation myocardial infarction (STEMI) and is of uncertain significance. The aim of this study was to identify and determine the predictors and prognostic implications of the presence of robust collaterals during STEMI. All patients presenting to a large tertiary centre with a STEMI undergoing percutaneous coronary intervention from 2010 to 2018 were reviewed. Patients with poor collateral recruitment were defined as those with Rentrop grade 0 or 1 collaterals, whilst patients with robust collateral recruitment were defined as Rentrop grade 2 or 3. A total of 1,625 patients were included in the study, with 1,280 (78.8%) patients having poor collateral recruitment and 345 patients (21.2%) having robust collateral recruitment. Patients with robust collaterals were younger (63.1 vs 65.1 years, p < 0.05), had a longer ischemic time (628.5 minutes vs 433.1 minutes, p < 0.0001), and more likely to have a chronic total occlusion of a noninfarct related artery (10.4% vs 5.3%, p < 0.001). The presence of robust collaterals was associated with higher rates of normal or mildly impaired left ventricular function (83.5% vs 63.2%, p < 0.0001) and lower in-hospital mortality (2.1% vs 7.6%, p < 0.0001). After correcting for left ventricular function, collateral recruitment was not an independent predictor of mortality. In conclusion, in patients presenting with STEMI, the presence of robust coronary collaterals appears to be associated with improved left ventricular function. Further research is required to identify mechanisms of collateral maturation and recruitment.

Prediction contribution of the cranial collateral circulation to the clinical and radiological outcome of ischemic stroke

BACKGROUND AND AIM

The extent of penumbra tissue and outcome in stroke patients depend on the collateral cranial vasculature. To provide optimal individualized care for stroke patients in the emergency room setting we investigated the predictive capability of a stringent evaluation of the collateral vessels in ischemic stroke on clinical outcome and infarct size.

METHODS

We retrospectively studied uniform clinical and radiological data of 686 consecutive patients admitted to the emergency department with suspected acute ischemic stroke. Cranial collateral vasculature status was graded using the initial CT-angiography. Outcome was measured by mRS, NIHSS and final infarct size at hospital discharge. All data were used to build a linear regression model to predict the patients´ outcome.

RESULTS

Univariate and multivariate analyses showed significant effects of the whole brain collateral vessel score on all outcome variables. Atherosclerosis and piale collateral status were associated with the final infarct volume (FIV). Atherosclerosis and age were associated with the NIHSS at discharge. The presence of atherosclerosis, glucose level on admission and age were associated with the mRS at discharge. The multivariate models were able to predict 29% of the variance of the mRS at discharge, 24% of the variance in FIV and 17% of the variance of the NIHSS at discharge. The whole brain collateral status and the presence of atherosclerosis were the most relevant predictors for the clinical and radiological outcome.

CONCLUSION

The whole brain collateral vasculature status is clearly associated with clinical and radiological outcome but in a multivariate model seems not sufficiently predictive for FIV, mRS and NIHSS outcome at discharge in non-preselected patients admitted to the emergency department with ischemic stroke.

Deacetylation of MRTF-A by SIRT1 defies senescence induced down-regulation of collagen type I in fibroblast cells

Aging provokes both morphological and functional changes in cells, which are accompanied by a fundamental shift in gene expression patterns. One of the characteristic alterations associated with senescence in fibroblast cells is the down-regulation of collagen type I genes. In the present study, we investigated the contribution of myocardin-related transcription factor A, or MRTF-A, in this process. In mouse embryonic fibroblast (MEF) cells and human foreskin fibroblast (HFF) cells, senescence, induced by either progressive passage or treatment with hydrogen peroxide (H₂O₂), led to augmented lysine acetylation of MRTF-A paralleling down-regulation of collagen type I and SIRT1, a lysine deacetylase. SIRT1 interacted with MRTF-A to promote MRTF-A deacetylation. SIRT1 over-expression or activation by selective agonists enhanced trans-activation of the collagen promoters by MRTF-A. On the contrary, SIRT1 depletion or inhibition by specific antagonists suppressed trans-activation of the collagen promoters by MRTF-A. Likewise, mutation of four lysine residues within MRTF-A rendered it more potent in terms of activating the collagen promoters but unresponsive to SIRT1. Importantly, SIRT1 activation in senescent fibroblasts mitigated repression of collagen type I expression whereas SIRT1 inhibition promoted the loss of collagen type I expression prematurely in young fibroblasts. Mechanistically, SIRT1 enhanced the affinity of MRTF-A for the collagen type I promoters. In conclusion, our data unveil a novel mechanism that underscores aging-associated loss of collagen type I in fibroblasts via SIRT1-mediated post-translational modification of MRTF-A.

Skeletal muscle as an experimental model of choice to study tissue aging and rejuvenation

Skeletal muscle is among the most age-sensitive tissues in mammal organisms. Significant changes in its resident stem cells (i.e., satellite cells, SCs), differentiated cells (i.e., myofibers), and extracellular matrix cause a decline in tissue homeostasis, function, and regenerative capacity. Based on the conservation of aging across tissues and taking advantage of the relatively well-characterization of the myofibers and associated SCs, skeletal muscle emerged as an experimental system to study the decline in function and maintenance of old tissues and to explore rejuvenation strategies. In this review, we summarize the approaches for understanding the aging process and for assaying the success of rejuvenation that use skeletal muscle as the experimental system of choice. We further discuss (and exemplify with studies of skeletal muscle) how conflicting results might be due to variations in the techniques of stem cell isolation, differences in the assays of functional rejuvenation, or deciding on the numbers of replicates and experimental cohorts.

Changes of the coronary arteries and cardiac microvasculature with aging: Implications for translational research and clinical practice

Aging results in functional and structural changes in the cardiovascular system, translating into a progressive increase of mechanical vessel stiffness, due to a combination of changes in micro-RNA expression patterns, autophagy, arterial calcification, smooth muscle cell migration and proliferation. The two pivotal mechanisms of aging-related endothelial dysfunction are oxidative stress and inflammation, even in the absence of clinical disease. A comprehensive understanding of the aging process is emerging as a primary concern in literature, as vascular aging has recently become a target for prevention and treatment of cardiovascular disease. Change of life-style, diet, antioxidant regimens, anti-inflammatory treatments, senolytic drugs counteract the pro-aging pathways or target senescent cells modulating their detrimental effects. Such therapies aim to reduce the ineluctable burden of age and contrast aging-associated cardiovascular dysfunction. This narrative review intends to summarize the macrovascular and microvascular changes related with aging, as a better understanding of the pathways leading to arterial aging may contribute to design new mechanism-based therapeutic approaches to attenuate the features of vascular senescence and its clinical impact on the cardiovascular system.

Who will benefit more from low-dose alteplase in acute ischemic stroke?

OBJECTIVES

Controversy persists over the benefits of low-dose versus standard-dose intravenous alteplase for the treatment of acute ischemic stroke. We sought to determine individual patient factors that contribute to the risk-benefit balance of low-dose alteplase treatment.

METHODS

Observational study using data from the Enhanced Control of Hypertension and Thrombolysis Stroke Study (ENCHANTED), an international, randomized, open-label, blinded-endpoint trial that assessed low-dose (0.6 mg/kg) versus standard-dose (0.9 mg/kg) intravenous alteplase in acute ischemic stroke patients. Logistic regression models were used to estimate the benefit of good functional outcome (scores 0 or 1 on the modified Rankin scale at 90 days) and risk (symptomatic intracerebral hemorrhage), under both regimens for individual patients. The net advantage for low-dose, relative to standard-dose, alteplase was calculated by dividing excess benefit by excess risk according to a combination of patient characteristics. The algorithms were externally validated in a nationwide acute stroke registry database in South Korea.

RESULTS

Patients with an estimated net advantage from low-dose alteplase, compared with without, were younger (mean age of 66 vs. 75 years), had lower systolic blood pressure (148 vs. 160 mm Hg), lower National Institute of Health Stroke Scale score (median of 8 vs. 16), and no atrial fibrillation (10.3% vs. 97.4%), diabetes mellitus (19.2% vs. 22.4%), or premorbid symptoms (defined by modified Rankin scale = 1) (16.3% vs. 37.8%).

CONCLUSION

Use of low-dose alteplase may be preferable in acute ischemic stroke patients with a combination of favorable characteristics, including younger age, lower systolic blood pressure, mild neurological impairment, and no atrial fibrillation, diabetes mellitus, or premorbid symptoms.

Neuroimaging selection for thrombectomy in pediatric stroke: a single-center experience

Background

The extended time window for endovascular therapy in adult stroke represents an opportunity for stroke treatment in children for whom diagnosis may be delayed. However, selection criteria for pediatric thrombectomy has not been defined.

Methods

We performed a retrospective cohort study of patients aged <18 years presenting within 24 hours of acute large vessel occlusion. Patient consent was waived by our institutional IRB. Patient data derived from our institutional stroke database was compared between patients with good and poor outcome using Fisher’s exact test, t-test, or Mann-Whitney U-test.

Results

Twelve children were included: 8/12 (66.7%) were female, mean age 9.7±5.0 years, median National Institutes of Health Stroke Scale (NIHSS) 11.5 (IQR 10–14). Stroke etiology was cardioembolic in 75%, dissection in 16.7%, and cryptogenic in 8.3%. For 2/5 with perfusion imaging, Tmax >4 s appeared to better correlate with NIHSS. Nine patients (75%) were treated: seven underwent thrombectomy alone; one received IV alteplase and thrombectomy, and one received IV alteplase alone. Favorable outcome was achieved in 78% of treated patients versus 0% of untreated patients (P=0.018). All untreated patients had poor outcome, with death (n=2) or severe disability (n=1) at follow-up. Among treated patients, older children (12.8±2.9 vs 4.2±5.0 years, P=0.014) and children presenting as outpatient (100% vs 0%, P=0.028) appeared to have better outcomes.

Conclusions

Perfusion imaging is feasible in pediatric stroke and may help identify salvageable tissue in extended time windows, though penumbral thresholds may differ from adult values. Further studies are needed to define criteria for thrombectomy in this unique population.

Cardiovascular drugs attenuated myocardial resistance against ischaemia-induced and reperfusion-induced injury in a rat model of repetitive occlusion

Objective

We investigated the impact of cardioprotective drugs on ST-elevation, arrhythmias and infarct size in a rat model of repetitive coronary artery occlusion.

Methods

Seventy Sprague-Dawley rats were randomised to two control and five treatment groups. Placebo was either implantation of a pneumatic occluder onto the left anterior descending coronary artery (LAD) without starting repetitive occlusion (SHAM) or subsequent RO of the LAD over 10 days without medication (ROP). Treatment groups underwent RO and additionally received nitroglycerin (NTG), metoprolol, verapamil (VER), ranolazine (RAN) or candesartan (CAN). Two weeks after the intervention, rats underwent a single, sustained LAD occlusion followed by reperfusion. To evaluate differences in cardiac resistance against myocardial ischaemia and reperfusion injury, cardiac surrogate parameters including maximal ST-elevation, arrhythmias and infarct size were assessed.

Results

Compared with sham, RO alone and RO plus nitroglycerin were associated with significantly lower maximal ST-elevation and percentage of infarcted myocardium (SHAM 0.12 mV, ROP 0.06 mV (p=0.004), NTG 0.05 mV (p=0.005); SHAM 16.2%, ROP 6.6% (p=0.008), NTG 5.9% (p=0.006). Compared with RO alone, RO plus RAN was accompanied by increased ST-elevation (0.13 mV, p=0.018) and RO plusVER or CAN by more infarcted myocardium (14.2%, p=0.004% and 15.5%, p=0.003, respectively). Rats treated with VER, RAN or CAN tended to severe arrhythmias more frequently than those of the control groups.

Conclusions

RO led to an increased myocardial resistance against ischaemia and reperfusion injury. Concomitant administration of nitroglycerin did not affect the efficacy of RO. Cardiovascular channel or receptor blockers reduced the efficacy of RO.

Pre-stroke warfarin enhancement of collateralization in acute ischemic stroke: a retrospective study

BACKGROUND

Warfarin therapies not only are used to prevent stroke in patients with high risk of cardioembolism such as patients with atrial fibrillation (AF) and rheumatic heart disease (RHD), but also was associated with lower stroke severity and more favorable functional outcomes in patients with acute ischemic stroke due to middle cerebral artery occlusion. It was speculated that pre-stroke warfarin may promote collateralization and result in reduced stroke severity. This study aimed to investigate the association between pre-stroke warfarin use and leptomeningeal collaterals in patients with acute ischemic stroke due to occlusion of the middle cerebral artery.

METHODS

We enrolled consecutive acute ischemic stroke patients (occlusion of the middle cerebral artery within 24 h) with known history of AF and/or RHD at the neurology department of the West China Hospital from May 2011 to April 2017. Computed tomography angiography (CTA) before treatment was used to detect the thrombus. Regional leptomeningeal collateral (rLMC) score based on CTA images was used to assess collateral circulation. Prior use of warfarin was recorded. Univariate and multivariate analyses were performed to detect the association of prior warfarin use with the collateral circulation.

RESULTS

A total of 120 patients were included; 29 (24.2%) were taking warfarin before stroke. The international normalized ratio (INR) in patients with prior warfarin use was 1.53 ± 1.00, compared with 1.02 ± 0.09 in patients without prior warfarin use (P < 0.001). Prior oral warfarin therapy was inversely associated with poor rLMC (OR = 0.07, 95%CI 0.01-0.44, P = 0.005). There were no associations between prior warfarin use and initial stroke severity or functional outcomes at 3 months.

CONCLUSION

Warfarin use seems improve collateralization in patients with acute stroke. However, clinical controlled studies should be used to verify this claim.

Mechanical Thrombectomy in Elderly Stroke Patients with Mild-to-Moderate Baseline Disability

Background

The number of elderly patients suffering from ischemic stroke is rising. Randomized trials of mechanical thrombectomy (MT) generally exclude patients over the age of 80 years with baseline disability. The aim of this study was to understand the efficacy and safety of MT in elderly patients, many of whom may have baseline impairment.

Methods

Between January 2015 and April 2017, 96 patients ≥80 years old who underwent MT for stroke were selected for a chart review. The data included baseline characteristics, time to treatment, the rate of revascularization, procedural complications, mortality, and 90-day good outcome defined as a modified Rankin Scale (mRS) score of 0-2 or return to baseline.

Results

Of the 96 patients, 50 had mild baseline disability (mRS score 0-1) and 46 had moderate disability (mRS score 2-4). Recanalization was achieved in 84% of the patients, and the rate of symptomatic hemorrhage was 6%. At 90 days, 34% of the patients had a good outcome. There were no significant differences in good outcome between those with mild and those with moderate baseline disability (43 vs. 24%, p = 0.08), between those aged ≤85 and those aged > 85 years (40.8 vs. 26.1%, p = 0.19), and between those treated within and those treated beyond 8 h (39 vs. 20%, p = 0.1). The mortality rate was 38.5% at 90 days. The Alberta Stroke Program Early CT Score (ASPECTS) and the National Institutes of Health Stroke Scale (NIHSS) predicted good outcome regardless of baseline disability (p < 0.001 and p = 0.009, respectively).

Conclusion

Advanced age, baseline disability, and delayed treatment are associated with sub-optimal outcomes after MT. However, redefining good outcome to include return to baseline functioning demonstrates that one-third of this patient population benefits from MT, suggesting the real-life utility of this treatment.

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.

The ageing heart: the systemic and coronary circulation

Most cardiovascular disease (CVD) occurs in patients over the age of 60. However, most evidence-based current cardiovascular guidelines lack evidence in an older population, due to the under-representation of older patients in randomised trials. Blood pressure rises with age due to increasing arterial stiffness, and stricter control results in improved outcomes. Myocardial ischaemia is also more common with increasing age, due to a combination of coronary artery disease and myocardial changes. However, despite higher rates of adverse outcomes, older patients are offered guideline-based therapy less frequently. Frailty is an independent predictor of mortality in adults over the age of 60, yet remains poorly assessed; slow gait speed is a key marker for the development of frailty and for adverse outcomes following intervention. Few trials have assessed frailty independent of age; however, there is evidence that non-frail older patients derive significant benefit from therapy, highlighting the urgent need to include frailty as a measure in clinical trials of treatment in CVD.In this review, the authors appraise the literature in regard to the cardiovascular changes with ageing, specifically in relation to the systemic and coronary circulation and with a particular emphasis on frailty and its implication in the evaluation and treatment of CVD.

Which Coronary Lesions Are More Prone to Cause Acute Myocardial Infarction?

Background

According to common belief, most myocardial infarctions (MIs) are due to the rupture of nonsevere, vulnerable plaques with < 70% obstruction. Data from recent trials challenge this belief, suggesting that the risk of coronary occlusion is, in fact, much higher after severe stenosis. The aim of this study was to investigate whether or not acute ST-elevation MIs result from high-grade stenoses by evaluating the presence of coronary collateral circulation (CCC).

Methods

We retrospectively included 207 consecutive patients who had undergone primary percutaneous coronary intervention for acute ST-elevation MI. Collateral blood flow distal to the culprit lesion was assessed by two investigators using the Rentrop scoring system.

Results

Out of the 207 patients included in the study, 153 (73.9%) had coronary collateral vessels (Rentrop 1-3). The Rentrop scores were 0, 1, 2, and 3 in 54 (26.1%), 50 (24.2%), 51 (24.6%), and 52 (25.1%) patients, respectively. Triglycerides, mean platelet volume (MPV), white cell (WBC) count, and neutrophil count were significantly lower in the group with good collateral vessels (p = 0.013, p = 0.002, p = 0.003, and p = 0.021, respectively).

Conclusion

More than 70% of the patients with acute MI had CCC with Rentrop scores of 1-3 during primary coronary angiography. This shows that most cases of acute MI in our study originated from underlying high-grade stenoses, challenging the common believe. Higher serum triglycerides levels, greater MPV, and increased WBC and neutrophil counts were independently associated with impaired development of collateral vessels.

Association of serum mimecan with angiographic coronary collateralization in patients with stable coronary artery disease and chronic total occlusion

BACKGROUND AND AIMS

Mimecan/osteoglycin is identified as an emerging biomarker of coronary atherosclerosis. We investigated whether and to what extent serum mimecan reflects angiographic coronary collateralization in patients with stable coronary artery disease and chronic total occlusion.

METHODS

Serum levels of mimecan were determined in 559 consecutive patients with stable angina and angiographic total occlusion of at least one major coronary artery. The degree of collaterals supplying the distal aspect of a total occlusion from the contra-lateral vessel was graded as poor (Rentrop score of 0 or 1) or good coronary collateralization (Rentrop score of 2 or 3).

RESULTS

Serum mimecan was significantly higher in patients with poor collateralization than in those with good collateralization, and correlated inversely with Rentrop score (adjusted Spearmen's r = -0.443, p < 0.001). The prevalence of poor coronary collaterals increased stepwise from the lowest to the highest quartile of serum mimecan (OR 2.140, 95% CI 1.793-2.555; p for trend < 0.001). After adjusting for age, gender, traditional risk factors for coronary artery disease, history of myocardial infarction, severity of coronary artery disease, renal function and C-reactive protein, serum mimecan (per SD) remained an independent determinant for poor collateralization (OR 2.674, 95% CI 2.057-3.475, p < 0.001). The diagnostic value of mimecan (per SD) for detecting poor collateralization was consistent when the patients were specified by gender, age, body mass index, presence or absence of hypertension and diabetes, and status of renal function (OR 2.075-6.932, p interaction ≥ 0.059).

CONCLUSION

Increased serum mimecan is associated with poor angiographic coronary collateralization in patients with chronic total occlusion.

Transmural distribution and connectivity of coronary collaterals within the human heart

Despite the importance of collateral vessels in human hearts, a detailed analysis of their distribution within the coronary vasculature based on three-dimensional vascular reconstructions is lacking. This study aimed to classify the transmural distribution and connectivity of coronary collaterals in human hearts. One normotrophic human heart and one hypertrophied human heart with fibrosis in the inferior wall from a previous infarction were obtained. After filling the coronary arteries with fluorescent replica material, hearts were frozen and alternately cut and block-face imaged using an imaging cryomicrotome. Transmural distribution, connectivity, and diameter of collaterals were determined. Numerous collateral vessels were found (normotrophic heart: 12.3 collaterals/cm(3); hypertrophied heart: 3.7 collaterals/cm(3)), with 97% and 92%, respectively, of the collaterals located within the perfusion territories (intracoronary collaterals). In the normotrophic heart, intracoronary collaterals {median diameter [interquartile range (IQR)]: 91.4 [73.0-115.7] μm} were most prevalent (74%) within the left anterior descending (LAD) territory. Intercoronary collaterals [median diameter (IQR): 94.3 (79.9-107.4) μm] were almost exclusively (99%) found between the LAD and the left circumflex artery (LCX). In the hypertrophied heart, intracoronary collaterals [median diameter (IQR): 101.1 (84.8-126.0) μm] were located within both the LAD (48%) and LCX (46%) territory. Intercoronary collaterals [median diameter (IQR): 97.8 (89.3-111.2) μm] were most prevalent between the LAD-LCX (68%) and LAD-right coronary artery (28%). This study shows that human hearts have abundant coronary collaterals within all flow territories and layers of the heart. The majority of these collaterals are small intracoronary collaterals, which would have remained undetected by clinical imaging techniques.

Senescence marker protein-30 deficiency impairs angiogenesis under ischemia

Aging decreases collateral-dependent flow recovery following acute arterial obstruction. However, the mechanisms are partially understood, therefore critical management has been lacked in clinical setting. Senescence marker protein-30 (SMP30) is a novel aging marker, which is assumed to act as an anti-aging factor in various organs. Therefore, we studied the effect of SMP30 on ischemia-induced collateral growth in SMP30 knockout (KO) mice, young and old C57BL/6 mice. The SMP30 expression in gastrocnemius tissue was decreased in old mice compared to that of young mice. The recovery of cutaneous blood flow in hind limb after femoral artery ligation and tissue capillary density recoveries were suppressed in SMP30 KO and old mice compared to those in young mice. Nitric oxide generation induced by l-arginine and GSH/GSSG in aorta of SMP30 KO and old mice were lower than those in young mice. The levels of NADPH oxidase activity and superoxide production in the ischemic tissue were higher in SMP30 KO and old mice than in young mice. The phosphorylated eNOS and Akt levels and VEGF levels in ischemic muscle were lower in SMP30 KO and old mice than in young mice. Deficiency of SMP30 exacerbates oxidative stress related to NADPH oxidase activity enhancement and impairs eNOS activity, which leads to rarefaction of angiogenesis induced by ischemia. These results suggest that SMP30 plays a key role in disrupting collateral growth under ischemia in aging.

Circulating MicroRNAs Characterizing Patients with Insufficient Coronary Collateral Artery Function

BACKGROUND

Coronary collateral arteries function as natural bypasses in the event of coronary obstruction. The degree of collateral network development significantly impacts the outcome of patients after an acute myocardial infarction (AMI). MicroRNAs (miRNAs, miRs) have arisen as biomarkers to identify heterogeneous patients, as well as new therapeutic targets in cardiovascular disease. We sought to identify miRNAs that are differentially expressed in chronic total occlusion (CTO) patients with well or poorly developed collateral arteries.

METHODS AND RESULTS

Forty-one CTO patients undergoing coronary angiography and invasive assessment of their coronary collateralization were dichotomized based on their collateral flow index (CFI). After miRNA profiling was conducted on aortic plasma, four miRNAs were selected for validation by real-time quantitative reverse transcription polymerase chain reaction in patients with low (CFI<0.39) and high (CFI>0.39) collateral artery capacity. We confirmed significantly elevated levels of miR423-5p (p<0.05), miR10b (p<0.05), miR30d (p<0.05) and miR126 (p<0.001) in patients with insufficient collateral network development. We further demonstrated that each of these miRNAs could serve as circulating biomarkers to discriminate patients with low collateral capacity (p<0.01 for each miRNA). We also determined significantly greater expression of miR30d (p<0.05) and miR126 (p<0.001) in CTO patients relative to healthy controls.

CONCLUSION

The present study identifies differentially expressed miRNAs in patients with high versus low coronary collateral capacity. We have shown that these miRNAs can function as circulating biomarkers to discriminate between patients with insufficient or sufficient collateralization. This is the first study to identify miRNAs linked to coronary collateral vessel function in humans.

Mitochondrial Aldehyde Dehydrogenase 2 Regulates Revascularization in Chronic Ischemia: Potential Impact on the Development of Coronary Collateral Circulation

OBJECTIVE

Revascularization is an essential process to compensate for cardiac underperfusion and, therefore, preserves cardiac function in the face of chronic ischemic injury. Recent evidence suggested a vital role of aldehyde dehydrogenase 2 (ALDH2) in cardiac protection after ischemia. This study was designed to determine whether ALDH2 regulates chronic ischemia-induced angiogenesis and to explore the underlying mechanism involved. Moreover, the clinical impact of the ALDH2 mutant allele on the development of coronary collateral circulation (CCC) was evaluated.

APPROACH AND RESULTS

Mice limb ischemia was performed. Compared with wild-type, ALDH2 deletion significantly reduced perfusion recovery, small artery and capillary density, and increased muscle atrophy in this ischemic model. In vitro, ALDH2-knockdown reduced proliferation, migration and hypoxia triggered endothelial tube formation of endothelial cells, the effects of which were restored by ALDH2 transfection. Further examination revealed that ALDH2 regulated angiogenesis possibly through hypoxia-inducible factor-1α/vascular endothelial growth factor pathways. To further discern the role of ALDH2 deficiency in the function of bone marrow stem/progenitor cells, cross bone marrow transplantation was performed between wild-type and ALDH2-knockout mice. However, there was no significant improvement for wild-type bone marrow transplantation into knockout mice. ALDH2 genotyping was screened in 139 patients with chronic total occlusion recruited to Zhongshan Hospital (2011.10-2014.4). Patients with poor CCC (Rentrop 0-1; n=51) exhibited a higher frequency of the AA genotype than those with enriched CCC (Rentrop 2-3; n=88; 11.76% versus 1.14%; P=0 0.01). However, the AA group displayed less enriched CCC frequency in Logistic regression model when compared with the GG group (odds ratio=0.08; 95% confidence interval, 0.009-0.701; P=0 0.026). Furthermore, serum vascular endothelial growth factor level tended to be lower in patients with ALDH2 mutation.

CONCLUSIONS

This study demonstrated that ALDH2 possesses an intrinsic capacity to regulate angiogenesis via hypoxia-inducible factor-1α and vascular endothelial growth factor. Patients with ALDH2-deficient genotype displayed a higher risk of developing poor CCC. Therapeutic individualization based on ALDH2 allele distribution may thus improve the therapeutic benefit, especially in the East Asian decedents.

Molecular controls of arterial morphogenesis

Formation of arterial vasculature, here termed arteriogenesis, is a central process in embryonic vascular development as well as in adult tissues. Although the process of capillary formation, angiogenesis, is relatively well understood, much remains to be learned about arteriogenesis. Recent discoveries point to the key role played by vascular endothelial growth factor receptor 2 in control of this process and to newly identified control circuits that dramatically influence its activity. The latter can present particularly attractive targets for a new class of therapeutic agents capable of activation of this signaling cascade in a ligand-independent manner, thereby promoting arteriogenesis in diseased tissues.

The effect of aging on the cutaneous microvasculature

Aging is associated with a progressive loss of function in all organs. Under normal conditions the physiologic compensation for age-related deficits is sufficient, but during times of stress the limitations of this reserve become evident. Explanations for this reduction in reserve include the changes in the microcirculation that occur during the normal aging process. The microcirculation is defined as the blood flow through arterioles, capillaries and venules, which are the smallest vessels in the vasculature and are embedded within organs and tissues. Optimal strategies to maintain the microvasculature following surgery and other stressors must use multifactorial approaches. Using skin as the model organ, we will review the anatomical and functional changes in the microcirculation with aging, and some of the available clinical strategies to potentially mitigate the effect of these changes on important clinical outcomes.

Patient selection for stroke endovascular therapy--DWI-ASPECTS thresholds should vary among age groups: insights from the RECOST study

BACKGROUND AND PURPOSE

The purpose of this study was to evaluate the benefits of endovascular intervention in large-vessel occlusion strokes, depending on age class.

MATERIALS AND METHODS

A clinical management protocol including intravenous treatment and mechanical thrombectomy was instigated in our center in 2009 (Prognostic Factors Related to Clinical Outcome Following Thrombectomy in Ischemic Stroke [RECOST] study). All patients with acute ischemic stroke with an anterior circulation major-vessel occlusion who presented within 6 hours were evaluated with an initial MR imaging examination and were analyzed according to age subgroups (younger than 50 years, 50-59 years, 60-69 years, 70-79 years; 80 years or older). The mRS score at 3 months was the study end point.

RESULTS

One hundred sixty-five patients were included in the analysis. The mean age was 67.4 years (range, 29-90 years). The mean baseline NIHSS score was 17.24 (range, 3-27). The mean DWI-derived ASPECTS was 6.4. Recanalization of TICI 2b/3 was achieved in 80%. At 3 months, 41.72% of patients had a good outcome, with a gradation of prognosis depending on the age subgroup and a clear cutoff at 70 years. Only 19% of patients older than 80 years had a good outcome at 3 months (mean ASPECTS = 7.4) with 28% for 70-79 years (mean ASPECTS = 6.8), but 58% for 60-69 years (mean ASPECTS = 6), 52% for 50-59 years (mean ASPECTS = 5.91), and 72% for younger than 50 years (mean ASPECTS = 6.31). In contrast, the mortality rate was 35% for 80 years and older, and 26% for 70-79 versus 5%-9% for younger than 70 years.

CONCLUSIONS

The elderly may benefit from thrombectomy when their ischemic core volume is low in comparison with younger patients who still benefit from acute recanalization despite larger infarcts. Stroke volume thresholds should, therefore, be related and adjusted to the patient's age group.

Resistance exercise and testosterone treatment alters the proportion of numerical density of capillaries of the left ventricle of aging Wistar rats

Changes in the heart compartments that leads to pathological cardiac hypertrophy can be related to testosterone reduction in aging males since heart cells are susceptible to androgens. Resistance exercise delays the changes of aging.

AIM

This study aimed to analyze alterations of the left ventricle of aged rats subjected to resistance exercise with administration of testosterone.

METHODS

Wistar rats were divided into five groups: C Group (control), S Group (sedentary), ST Group (sedentary treated with testosterone), T Group (trained) and TT Group (trained and treated with testosterone), strength training protocol and testosterone treatment were 16 weeks long. All groups were sacrificed at 16 months except for C group, sacrificed at 13 months.

RESULTS

There was no change in the weight of the heart or the left ventricle between the groups. ST group showed increase in Nv [cap] density of capillaries and collagen, with no differences in interstitial space. Both trained groups (T and TT) showed increase in the numerical density of capillaries (Nv [cap]) and in the interstitial space, with no changes in collagen.

CONCLUSION

Resistance exercise combined with testosterone triggered a response of compensatory adjustment in the increase of Nv [cap], collagen and interstitial space, increasing perfusion and nutrition to the heart.

Chronic stress impairs collateral blood flow recovery in aged mice

Chronic stress is associated with increased risk of cardiovascular diseases. Aging is also associated with vascular dysfunction. We hypothesize that chronic stress accelerates collateral dysfunction in old mice. Mice were subjected to either chronic social defeat (CSD) or chronic cold stress (CCS). The CSD mice were housed in a box inside an aggressor's cage and exposed to the aggressor. The CCS group was placed in iced water. After chronic stress, mice underwent femoral artery ligation (FAL) and flow recovery was measured. For the CSD group, appearance and use scores of the foot and a behavioral test were performed. CSD impaired collateral flow recovery after FAL. Further, stressed mice had greater ischemic damage, impaired foot function, and altered behavior. The CCS mice also showed impaired collateral flow recovery. Chronic stress causes hind limb collateral dysfunction in old mice, a conclusion reinforced by the fact that two types of stress produced similar changes.

Glycation: the angiogenic paradox in aging and age-related disorders and diseases

Angiogenesis is generally a quiescent process which, however, may be modified by different physiological and pathological conditions. The "angiogenic paradox" has been described in diabetes because this disease impairs the angiogenic response in a manner that differs depending on the organs involved and disease evolution. Aging is also associated with pro- and antiangiogenic processes. Glycation, the post-translational modification of proteins, increases with aging and the progression of diabetes. The effect of glycation on angiogenesis depends on the type of glycated proteins and cells involved. This complex link could be responsible for the "angiogenic paradox" in aging and age-related disorders and diseases. Using diabetes as a model, the present work has attempted to review the age-related angiogenic paradox, in particular the effects of glycation on angiogenesis during aging.

The human coronary collateral circulation: development and clinical importance

Coronary collaterals are an alternative source of blood supply to myocardium jeopardized by ischaemia. In comparison with other species, the human coronary collateral circulation is very well developed. Among individuals without coronary artery disease (CAD), there are preformed collateral arteries preventing myocardial ischaemia during a brief vascular occlusion in 20-25%. Determinants of such anastomoses are low heart rate and the absence of systemic arterial hypertension. In patients with CAD, collateral arteries preventing myocardial ischaemia during a brief occlusion are present in every third individual. Collateral flow sufficient to prevent myocardial ischaemia during coronary occlusion amounts to one-fifth to one-fourth the normal flow through the open vessel. Myocardial infarct size, the most important prognostic determinant after such an event, is the product of coronary artery occlusion time, area at risk for infarction, and the inverse of collateral supply. Well-developed coronary collateral arteries in patients with CAD mitigate myocardial infarcts and improve survival. Approximately one-fifth of patients with CAD cannot be revascularized by percutaneous coronary intervention or coronary artery bypass grafting. Therapeutic promotion of collateral growth is a valuable treatment strategy in those patients. It should aim at growth of large conductive collateral arteries (arteriogenesis). Potential arteriogenic approaches include the treatment with granulocyte colony-stimulating factor, physical exercise training, and external counterpulsation.