The role of gender and sex hormones in ischemic–reperfusion injury in isolated rat hearts

Morphine exacerbates myocardial ischemia/reperfusion injury by overactivation of NLRP3 inflammasome via suppression of p-TRPV1 in male rats

The pathology of early MIRI (myocardial ischemia/reperfusion injury) is characterized by sterile inflammation. TRPV1 (transient receptor potential vanilloid 1) and NLRP3 inflammasome sense harmful stimulation and modulate inflammation in cardiomyocytes. We recently demonstrated morphine downregulated p-TRPV1 and exacerbated MIRI. In this study, we investigate the potential crosstalk of TRPV1 and NLRP3 inflammasome activities and a potential modulatory effect of morphine on the interaction in MIRI. In vivo and in vitro experiments were conducted. Coding RNA and pharmacological modulations were used in this study. We found MI/R (myocardial ischemia and reperfusion) upregulated p-TRPV1 without change in expression of NLRP3 inflammasome. Giving morphine during myocardial ischemia increased ventricular arrythmia, reduced heart rate and +dp/dt Max in reperfusion, and increased serum cTnI (cardiac troponin I) and infarct size. Suppression of p-TRPV1 but enhancement of NLRP3 inflammasome activity at the end of MI/R were detected. The alterations were reversed by an opioid μ-receptor antagonist or a NLRP3 inhibitor. Giving TRPV1 antagonist or knockdown of TRPV1 in cultured primary cardiomyocytes inhibited p-TRPV1 but increased NLRP3 inflammasome and the downstream cytokines and LDH (lactate dehydrogenase) in the supernatants. Conversely, treatment with capsaicin (a TRPV1 agonist) or upregulation of TRPV1 via transfection of Ad-TRPV1 elevated p-TRPV1 and reduced NLRP3 and LDH. The results indicated morphine treatment during myocardial ischemia aggravates MIRI by increasing the activity of NLRP3 inflammasome, via suppressing the inhibitory effect of p-TRPV1 on NLRP3 inflammasome. Targeting the signal chain of opioid μ-receptor agonist/TRPV1/NLRP3 inflammasome may find a novel way to improve MIRI.

Sex differences in extracorporeal cardiopulmonary resuscitation for out-of-hospital cardiac arrest: nationwide multicenter retrospective study in Japan

BACKGROUND

Previous studies examining sex differences in patients undergoing extracorporeal cardiopulmonary resuscitation (ECPR) for out-of-hospital cardiac arrest (OHCA) have indicated that women have favorable outcomes; however, detailed evidence remains lacking. We aimed to investigate sex differences in the backgrounds and outcomes of patients undergoing ECPR for OHCA.

METHODS

This study was a secondary analysis of the registry from the SAVE-J II study, a retrospective multicenter study conducted in Japan from 2013 to 2018. Adult patients without external causes who underwent ECPR for OHCA were included. The primary outcome was a favorable neurological outcome (Cerebral Performance Status 1 or 2) at hospital discharge. We used multilevel logistic regression to evaluate the association of sex differences, adjusting for center-level (hospital) and individual-level variables (patient background, cardiac arrest situation, and in-hospital intervention factors). For sensitivity analyses, we performed three models of multilevel logistic regression when selecting confounders.

RESULTS

Among the 1819 patients, 1523 (83.7%) were men, and 296 (16.3%) were women. The median age (61.0 vs. 58.0 years), presence of a witness (78.8% vs. 79.2%), and occurrence of bystander CPR (57.5% vs. 61.6%) were similar between groups. Women were more likely to present with an initial non-shockable rhythm (31.7% vs. 49.7%), as well as a non-shockable rhythm at hospital arrival (52.1% vs. 61.5%) and at ECMO initiation (48.1% vs. 57.1%). The proportion of favorable neurological outcomes was 12.3% in males and 15.9% in females (p = 0.10). Multilevel logistic regression analysis showed that the female sex was significantly associated with a favorable neurologic outcome at discharge (adjusted odds ratio: 1.60 [95% confidence interval: 1.05-2.43]; p = 0.03). This advantage in women was consistently observed in the sensitivity analyses.

CONCLUSIONS

The female sex is significantly associated with favorable neurological outcomes at hospital discharge in patients who received ECPR for OHCA.

Social determinants and pre-arrest care patterns associated with cardiac arrest and mortality

BACKGROUND

Understanding the impact of social determinants of health (SDOH) on CA, including access to care pre-cardiac arrest (CA) can improve outcomes. Large databases, such as Epic Cosmos, can help identify trends in patient demographics and SDOH that identify gaps in care. The purpose of this study was to determine the incidence of CA and subsequent mortality in a large national database across patient demographics and social determinants and characterize pre-arrest care patterns.

METHODS

This was a retrospective cohort study using a large national deidentified electronic health database (Epic Cosmos) with 227 million patients. Inclusion criteria was ED encounter for CA (ICD-10-CM: I46). Patient demographics and social determinants included age, sex, race, ethnicity, social vulnerability index (SVI, a composite measure with greater SVI representing more vulnerability). The primary outcome was difference in CA incidence between groups, reported as odds ratios (ORs). The secondary outcomes were 1) incidence of pre-arrest care within 30 days and 2) post-arrest mortality at 7,30, and 180 days. Statistical analysis was performed using Chi-squared analysis (unadjusted OR) and aggregated logistic procedure (adjusted OR).

RESULTS

There were 201,846 ED visits for CA between April 20, 2020, and April 19, 2023 (0.11% incidence). For all ages, males had a higher incidence of CA (OR 1.76, p < 0.0001). Black, Native Hawaiian or Pacific Islander, and American Indian or Alaska Native had a higher OR of CA while Asian patients were less likely than White patients (adjusted OR 1.85, 1.44,1.51, and 0.81 respectively, all p < 0.0001). Hispanic/Latino patients had a lower OR of CA (adjusted OR 0.72, p < 0.0001). CA was more common in the highest SVI quartile compared to the lowest (adjusted OR 1.71, p < 0.0001). Significant heterogeneities were identified in pre-arrest care across patient demographics and social determinants, where ED visits were more common than office visits among male patients, patients in the highest SVI, Hispanic/Latino, and minority patients, except for Asian patients. Post-arrest mortality after 30 days was highest in females, Black patients, and patients in the highest SVI.

CONCLUSIONS

SDOH have a significant impact on the risk of CA, pre-arrest care patterns, and post-arrest mortality. Determining the impact that SDOH have on the CA care continuum provides can provide actionable targets to prevent CA and subsequent mortality.

Mortality and healthcare resource utilisation after cardiac arrest in the United States - A 10-year nationwide analysis prior to the COVID-19 pandemic

AIM

Understanding the public health burden of cardiac arrest (CA) is important to inform healthcare policies, particularly during healthcare crises such as the COVID-19 pandemic. This study aimed to analyse outcomes of in-hospital mortality and healthcare resource utilisation in adult patients with CA in the United States over the last decade prior to the COVID-19 pandemic.

METHODS

The United States (US) National Inpatient Sample was utilised to identify hospitalised adult patients with CA between 2010 and 2019. Logistic and Poisson regression models were used to analyse outcomes by adjusting for 47 confounders.

RESULTS

248,754 adult patients with CA (without "Do Not Resuscitate"-orders) were included in this study, out of which 57.5% were male. In-hospital mortality was high with 51.2% but improved significantly from 58.3% in 2010 to 46.4% in 2019 (P < 0.001). Particularly, elderly patients, non-white patients and patients requiring complex therapy had a higher mortality rate. Although the average hospital LOS decreased by 11%, hospital expenses have increased by 13% between 2010 and 2019 (each P < 0.001), presumably due to more frequent use of mechanical circulatory support (MCS, e.g. ECMO from 2.6% to 8.7% or Impella® micro-axial flow pump from 1.8% to 14.2%). Strong disparities existed among patient age groups and ethnicities across the US. Of note, the number of young adults with CA and opioid-induced CA has almost doubled within the study period.

CONCLUSION

Over the last ten years prior to the COVID-19 pandemic, CA-related survival has incrementally improved with shorter hospitalisations and increased medical expenses, while strong disparities existed among different age groups and ethnicities. National standards for CA surveillance should be considered to identify trends and differences in CA treatment to allow for standardised medical care.

Sex and gender differences in intensive care medicine

Despite significant advancements in critical care medicine, limited attention has been given to sex and gender disparities in management and outcomes of patients admitted to the intensive care unit (ICU). While "sex" pertains to biological and physiological characteristics, such as reproductive organs, chromosomes and sex hormones, "gender" refers more to sociocultural roles and human behavior. Unfortunately, data on gender-related topics in the ICU are lacking. Consequently, data on sex and gender-related differences in admission to the ICU, clinical course, length of stay, mortality, and post-ICU burdens, are often inconsistent. Moreover, when examining specific diagnoses in the ICU, variations can be observed in epidemiology, pathophysiology, presentation, severity, and treatment response due to the distinct impact of sex hormones on the immune and cardiovascular systems. In this narrative review, we highlight the influence of sex and gender on the clinical course, management, and outcomes of the most encountered intensive care conditions, in addition to the potential co-existence of unconscious biases which may also impact critical illness. Diagnoses with a known sex predilection will be discussed within the context of underlying sex differences in physiology, anatomy, and pharmacology with the goal of identifying areas where clinical improvement is needed. To optimize patient care and outcomes, it is crucial to comprehend and address sex and gender differences in the ICU setting and personalize management accordingly to ensure equitable, patient-centered care. Future research should focus on elucidating the underlying mechanisms driving sex and gender disparities, as well as exploring targeted interventions to mitigate these disparities and improve outcomes for all critically ill patients.

Age and sex differences in outcomes after in-hospital cardiac arrest

INTRODUCTION

While specific factors have been associated with outcomes after in-hospital cardiac arrest, the association between sex and outcomes remains debated. Moreover, age-specific sex differences in outcomes have not been fully characterized in this population.

METHODS

Adult patients (≥18 years) with an index in-hospital cardiac arrest were included from the Danish In-Hospital Cardiac Arrest Registry (DANARREST) from January 1st, 2017 to December 31st, 2018. Population-based registries were used to obtain data on patient characteristics, cardiac arrest characteristics, and outcomes. Unadjusted and adjusted estimates for return of spontaneous circulation (ROSC), survival to 30 days, survival to one year, duration of resuscitation, and post-cardiac arrest time-to-death were computed.

RESULTS

A total of 3266 patients were included, of which 2041 (62%) patients were male with a median age of 73 years (quartiles: 64, 80). Among 1225 (38%) female patients, the median age was 76 years (quartiles: 67, 83). Younger age was associated with higher odds of ROSC and survival. Sex was not associated with ROSC and survival in the unadjusted analyses. In the adjusted analyses, women had 1.32 (95%CI: 1.12, 1.54) times the odds of survival to 30 days and 1.26 (95%CI: 1.02, 1.57) times the odds of survival to one year compared to men. The overall association between sex and survival did not vary substantially across age categories, although female sex was associated with a higher survival within certain age categories. Among patients who did not achieve ROSC, female sex was associated with a shorter duration of resuscitation, which was more pronounced in younger age categories.

CONCLUSIONS

In this study of patients with in-hospital cardiac arrest, female sex was associated with a shorter duration of resuscitation among patients without ROSC but a higher survival to 30 days and one year. While the overall association between sex and outcomes did not vary substantially across age categories, female sex was associated with a higher survival within certain age categories.

Sex differences in acute cardiovascular care: a review and needs assessment

Despite significant progress in the care of patients suffering from cardiovascular disease, there remains a persistent sex disparity in the diagnosis, management, and outcomes of these patients. These sex disparities are seen across the spectrum of cardiovascular care, but, are especially pronounced in acute cardiovascular care. The spectrum of acute cardiovascular care encompasses critically ill or tenuous patients with cardiovascular conditions that require urgent or emergent decision-making and interventions. In this narrative review, the disparities in the clinical course, management, and outcomes of six commonly encountered acute cardiovascular conditions, some with a known sex-predilection will be discussed within the basis of underlying sex differences in physiology, anatomy, and pharmacology with the goal of identifying areas where improvement in clinical approaches are needed.

The Link Between Sex Hormones and Susceptibility to Cardiac Arrhythmias: From Molecular Basis to Clinical Implications

It is well-known that gender is an independent risk factor for some types of cardiac arrhythmias. For example, males have a greater prevalence of atrial fibrillation and the Brugada Syndrome. In contrast, females are at increased risk for the Long QT Syndrome. However, the underlying mechanisms of these gender differences have not been fully identified. Recently, there has been accumulating evidence indicating that sex hormones may have a significant impact on the cardiac rhythm. In this review, we describe in-depth the molecular interactions between sex hormones and the cardiac ion channels, as well as the clinical implications of these interactions on the cardiac conduction system, in order to understand the link between these hormones and the susceptibility to arrhythmias.

Cardiac function and tolerance to ischemia/reperfusion injury in a rat model of polycystic ovary syndrome during the postmenopausal period

AIMS

There is much controversy regarding whether cardiovascular events increase in women with polycystic ovary syndrome (PCOS) with aging. Considering the lack of possibility of certain investigations in humans, animal models of PCOS may be suitable resources to obtain the useful data needed. In this study; we aimed to investigate whether cardiac function and tolerance to ischemia/reperfusion (I/R) injury worsen in postmenopausal rats, who had PCOS at younger ages, compared to controls.

MAIN METHODS

The hearts of aged rats with a history of PCOS and their controls were isolated and perfused in a Langendorff apparatus. Values of hemodynamic parameters, including left ventricular systolic pressure (LVSP), left ventricular developed pressure (LVDP), rate pressure product (RPP) and peak rates of positive and negative changes in left ventricular pressure (±dp/dt) were recorded using a power lab system. Blood serum levels of total testosterone (TT) and estradiol (E2) were determined by ELISA kits. Generalized Estimating Equation Model and t-student unpaired test results were used to compare the findings documented between two groups.

KEY FINDINGS

No statistically significant differences were observed in hemodynamic parameters of the heart including, LVSP, LVDP, RPP and ±dp/dt, between the rats of two groups of study, at baseline or before ischemia and after I/R. Nor were any significant differences observed in the levels of two hormones between the two groups (p > 0.05).

SIGNIFICANCE

History of PCOS during reproductive ages should not be considered an important risk factor for reduction in cardiac contractile function or less tolerance to I/R injury during the postmenopausal period.

Sex-specific differences in survival after out-of-hospital cardiac arrest: a nationwide, population-based observational study

Background

It remains unclear whether men have more favorable survival outcomes after out-of-hospital cardiac arrest (OHCA) than women.

Methods

We reviewed a total of 386,535 patients aged ≥ 18 years with OHCA who were included in the Japanese registry from 2013 to 2016. The study endpoints were the rates of 1-month survival and neurologically intact survival (Cerebral Performance Category Scale score = 1 or 2). Based on age, the reviewed patients were categorized into the following eight groups: < 30, 30–39, 40–49, 50–59, 60–69, 70–79, 80–89, and ≥ 90 years. The survival outcomes in men and women were compared using hierarchical propensity score matching.

Results

The crude survival rate was significantly higher in men than in women in five groups: 30–39, 40–49, 50–59, 60–69, and 70–79 years (all P < 0.001). Similarly, the crude neurologically intact survival rate was significantly higher in men than in women in seven groups: < 30, 30–39, 40–49, 50–59, 60–69, 70–79, and 80–89 years (all P < 0.005). However, multivariate logistic regression analysis of each group revealed no significant sex-specific differences in 1-month survival outcomes (all P > 0.02). Moreover, after hierarchical propensity score matching, the survival outcomes did not significantly differ between both sexes (all P > 0.05).

Conclusions

No significant sex-specific differences were found in the rates of 1-month survival and neurologically intact survival after OHCA.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2547-x) contains supplementary material, which is available to authorized users.

Sports activity and paediatric out-of-hospital cardiac arrest at schools in Japan

BACKGROUND

Sudden cardiac death during exercise or sports is an important problem among young athletes and non-athletes. An understanding of the epidemiological features of sports-related out-of-hospital cardiac arrest (OHCA) among children is crucial for planning approaches for prevention and better outcomes of paediatric OHCAs. We assessed the characteristics and outcomes of sports-related OHCA among children at schools in Japan to prevent sports-related paediatric OHCA at schools.

METHODS

The Stop and Prevent cardIac aRrest, Injury, and Trauma in Schools (SPIRITS) is a nationwide, prospective, observational study linking databases of two nationally representative registries. Data on the characteristics and outcomes of sports-related paediatric OHCA at schools in Japan were obtained from these databases.

RESULTS

Between 2008 and 2015, 188 sports-related paediatric OHCAs due to presumed cardiac origin occurred. The greatest proportion of OHCA during or after sports was due to long-distance running (21.8%), followed by soccer/futsal (13.3%), basketball (12.2%), and baseball/rubber-ball baseball (11.2%). We also assessed the association between prehospital factors and one-month survival with favourable neurological outcome after sports-related OHCA. The proportions of ventricular fibrillation as the first documented rhythm, bystander cardiopulmonary resuscitation (CPR), and public-access defibrillation (PAD) were 87.8%, 87.2%, and 63.3%, respectively. Compared with the non-PAD group, the adjusted odds ratio (95% confidence interval) of the PAD group was 3.64 (1.78-7.45).

CONCLUSIONS

In Japan, 188 schoolchildren experienced OHCAs of cardiac origin occurring during or after sports activity at schools during the 8-year period. Increasing PAD is essential to enhance better neurological outcome after sports-related OHCA among students.

The impact of sex and age on neurological outcomes in out-of-hospital cardiac arrest patients with targeted temperature management

Background

There are conflicting data regarding sex-based differences in the outcomes of out-of-hospital cardiac arrest (OHCA) patients, and whether the specific sex advantage is age-specific remains unclear. We assessed the impact of the interactions between sex and age on the neurological outcomes of OHCA patients receiving targeted temperature management (TTM).

Methods

Data collected from 2007 to 2012 for a multicenter, registry-based study of the Korean Hypothermia Network were analyzed. We used a multivariate logistic regression model with an interaction term (age × sex) as the final model for the outcomes. To evaluate the association between sex and outcome in specific age groups, all patients were divided into specific age subgroups, and the adjusted ORs and 95% CIs of good neurological outcomes for males were calculated for each age group. Finally, the ORs of a good neurological outcome for the specific age groups compared with the 50- to 59-year-old group were calculated for both sexes.

Results

In the interaction analysis, age was a negative prognostic factor (OR, 0.95 [95% CI, 0.93-0.98]), whereas sex was not associated with neurological outcomes (OR, 3.74 [95% CI, 0.85–16.35]), and reproductive age in females (age, < 50 years) was also not associated with good neurological outcomes. After the patients were divided into five age groups, sex was not an independent predictor of neurological outcomes across all age groups. Patients of both sexes aged < 40 years had significantly better outcomes than patients in the 50- to 59-year-old group (males, OR, 4.03 [95% CI, 1.86–8.73]; females, OR, 10.34 [95% CI, 1.99–53.85]). Males aged ≥ 70 years had significantly poorer neurological outcomes than those in the 50- to 59-year-old group (OR, 0.15 [95% CI, 0.07–0.32]), but this outcome was not observed for females (OR, 0.78 [95% CI, 0.20–3.14]).

Conclusions

Sex did not influence the neurological outcomes of TTM-treated OHCA patients. In contrast to the outcomes in males, the neurological outcomes of females worsened from 18 to 59 years of age and then remained constant.

Sub-therapeutic doses of fluvastatin and valsartan are more effective than therapeutic doses in providing beneficial cardiovascular pleiotropic effects in rats: A proof of concept study

BACKGROUND

Statins and sartans can, in therapeutic doses, induce pleiotropic cardiovascular effects. Similar has recently been shown also for sub-therapeutic doses. We thus explored and compared the cardiovascular pleiotropic efficacy of sub-therapeutic vs. therapeutic doses.

METHODS

Wistar rats were randomly divided into 7 groups receiving fluvastatin, valsartan and their combination in sub-therapeutic and therapeutic doses, or saline. After 6weeks, the animals were euthanised, their hearts and thoracic aortas isolated, and blood samples taken. Endothelium-dependent relaxation of the thoracic aortae and ischaemic-reperfusion injury of the isolated hearts were assessed along with the related serum parameters and genes expression.

RESULTS

Fluvastatin and valsartan alone or in combination were significantly more effective in sub-therapeutic than therapeutic doses. The sub-therapeutic combination greatly increased thoracic aorta endothelium-dependent relaxation and maximally protected the isolated hearts against ischaemia-reperfusion injury and was thus most effective. Beneficial effects were accompanied by increased levels of nitric oxide (NO) and decreased levels of asymmetric dimethylarginine (ADMA) in the serum (again prominently induced by the sub-therapeutic combination). Furthermore, nitric oxide synthase 3 (NOS3) and endothelin receptor type A (EDNRA) genes expression increased, but only in both combination groups and without significant differences between them. In the therapeutic dose groups, fluvastatin and valsartan decreased cholesterol values and systolic blood pressure.

CONCLUSION

Sub-therapeutic doses of fluvastatin and valsartan are more effective in expressing cardiovascular pleiotropic effects than therapeutic doses of fluvastatin and/or valsartan. These results could be of significant clinical relevance.

Arrhythmogenic effect of androgens on the rat heart

In most species androgens shorten the cardiac action potential and reduce the risk of afterdepolarizations. Despite the central role of the rat model in physiological studies, the effects of androgens on the rat heart are still inconclusive. We therefore performed electrophysiological studies on the perfused rat right ventricular free wall. We found a correlation between androgenic activity and a propensity to generate ventricular ectopic action potentials. We also found that the testosterone treatment increased action potential duration at 90 % of repolarization (APD90), while androgenic inhibition increased the time to peak and decreased APD90. We observed that the voltage-gated potassium channel Kv4.3 and the bi-directional membrane ion transporter NCX in the rat myocardium were regulated by androgenic hormones. One possible explanation for these findings is that due to the expression of specific ion channels in the rat myocardium, the action potential response to its hormonal background is different from those described in other experimental models. Our results indicate that androgenic control of NCX expression plays a key role in determining arrhythmogenicity in the rat heart.

Cardioprotective effects of silver fir (Abies alba) extract in ischemic-reperfused isolated rat hearts

Background

Silver fir trunk extract (SFTE) is a complex mixture of antioxidative polyphenols (lignans and phenolic acids) from the trunks of silver fir trees (Abies alba, lignum). In our previous study, we have shown that SFTE exerts strong antioxidative and protective effects against atherogenic, diet-induced arterial wall damage.

Objective

The aim of the present study was to test the potential protective effects of SFTE and its compounds, two phenolic acids (p-coumaric and protocatechuic acids) in ischemia–reperfusion injury of isolated rat hearts.

Design

Isolated hearts of Wistar rats aged 4–8 weeks were exposed to perfusion, ischemia, and reperfusion periods. The experiments were performed using the following five groups: control, SFTE (10 µg/L), SFTE (100 µg/L), protocatechuic acid, and p-coumaric. Aortas were isolated to measure vascular responses in the presence of N^ω-Nitro-L-arginine.

Results

SFTE dose-dependently reduced ischemic-reperfusion heart damage, which was indicated as the decrease in the lactate dehydrogenase (LDH) release rate and arrhythmias duration by 80% and an increase in coronary flow rate during the reperfusion period. Two tested compounds (p-coumaric and protocatechuic acids) acted less cardioprotective, since they decreased the duration of arrhythmias only by 40 and 45%, respectively, and did not decrease LDH release rates during the reperfusion period. Only p-coumaric acid increased coronary flow rates, whereas protocatechuic acid did not.

Conclusions

We conclude that the SFTE exerted the strongest cardioprotective effect, whereas its constituents (the p-coumaric and protocatechuic acids) were less effective in inducing cardioprotection.

Associations among gender, marital status, and outcomes of adult in-hospital cardiac arrest: A retrospective cohort study

AIM

To analyse the association between gender and outcomes of in-hospital cardiac arrest (IHCA) and the influences of age and marital status on the gender-based difference in clinical outcome.

METHODS

This retrospective observational study conducted in a single medical centre evaluated patients who had experienced IHCA from 2006 to 2014. Multivariate logistic regression analysis was used to study associations between independent variables and outcomes. Patients 18-49 years old were considered of reproductive age. The presence or absence of a legitimate spouse was retrieved from the family pedigree presented in the medical records. Reproductive age and marital status were each analysed as an interaction term with gender.

RESULTS

A total of 1524 patients, of which 598 were women (39.2%), were included in this study. There were 269 patients (17.7%) of reproductive age and 490 patients (32.2%) without a living spouse. Only 215 patients (14.1%) survived to hospital discharge. Among these, 110 patients (7.2%) demonstrated a favourable neurological status. Our analysis indicated that being female was inversely associated with a favourable neurological outcome (odds ratio [OR], 0.51; 95% confidence interval [CI], 0.29-0.87; p=0.02). Being female without a living spouse was inversely associated with a favourable neurological outcome (OR, 0.43; 95% CI, 0.17-0.96; p=0.05). Neither female nor female-associated interaction terms were significantly associated with survival to hospital discharge.

CONCLUSION

Female patients with IHCA had worse neurological outcomes than their male counterparts, especially for women without a living spouse. However, survival outcome did not differ between genders.

Estrogenic Impact on Cardiac Ischemic/Reperfusion Injury

The increase in cardiovascular disease and metabolic syndrome incidence following the onset of menopause has highlighted the role of estrogen as a cardiometabolic protective agent. Specifically regarding the heart, estrogen induced an improvement in cardiac function, preserved calcium homeostasis, and inhibited the mitochondrial apoptotic pathway. The beneficial effects of estrogen in relation to cardiac ischemia/reperfusion (I/R) injury, such as reduced infarction and ameliorated post-ischemic recovery, have also been shown. Nevertheless, controversial findings exist and estrogen therapy is reported to be related to a higher rate of thromboembolic events and atrial fibrillation in post-menopausal women. Therefore, greater clarification is needed to evaluate the exact potential of estrogen use in cases of cardiac I/R injury. This article reviews the effects of estrogen, in both acute and chronic treatment, and collates the studies with regard to their in vivo, in vitro, or clinical trial settings in cases of cardiac I/R injury and myocardial infarction.

Sex- and gender-specific research priorities in cardiovascular resuscitation: proceedings from the 2014 Academic Emergency Medicine Consensus Conference Cardiovascular Resuscitation Research Workgroup

Significant sex and gender differences in both physiology and psychology are readily acknowledged between men and women; however, data are lacking regarding differences in their responses to injury and treatment and in their ultimate recovery and survival. These variations remain particularly poorly defined within the field of cardiovascular resuscitation. A better understanding of the interaction between these important factors may soon allow us to dramatically improve outcomes in disease processes that currently carry a dismal prognosis, such as sudden cardiac arrest. As part of the 2014 Academic Emergency Medicine consensus conference "Gender-Specific Research in Emergency Medicine: Investigate, Understand, and Translate How Gender Affects Patient Outcomes," our group sought to identify key research questions and knowledge gaps pertaining to both sex and gender in cardiac resuscitation that could be answered in the near future to inform our understanding of these important issues. We combined a monthly teleconference meeting of interdisciplinary stakeholders from largely academic institutions with a focused interest in cardiovascular outcomes research, an extensive review of the existing literature, and an open breakout session discussion on the recommendations at the consensus conference to establish a prioritization of the knowledge gaps and relevant research questions in this area. We identified six priority research areas: 1) out-of-hospital cardiac arrest epidemiology and outcome, 2) customized resuscitation drugs, 3) treatment role for sex steroids, 4) targeted temperature management and hypothermia, 5) withdrawal of care after cardiac arrest, and 6) cardiopulmonary resuscitation training and implementation. We believe that exploring these key topics and identifying relevant questions may directly lead to improved understanding of sex- and gender-specific issues seen in cardiac resuscitation and ultimately improved patient outcomes.

Aromatase transgenic upregulation modulates basal cardiac performance and the response to ischemic stress in male mice

Estrogen in females is conventionally considered a cardioprotective influence, but a role for estrogen in male cardioprotection has yet to be defined. Estrogen biosynthesis from testosterone is regulated by aromatase. Aromatase has recently been shown to be expressed in the adult heart, although little is known about its involvement in the regulation of myocardial function and stress responses. The goal of this study was to determine whether upregulation of tissue aromatase expression could improve ischemic resilience in male hearts. Isolated hearts from male transgenic aromatase-overexpressing (AROM+; high estrogen, low testosterone) mice and wild-type (WT) mice (12 wk) were Langendorff perfused and subjected to ischemia-reperfusion (25 min ischemia and 60 min of reperfusion). Basal systolic function was lower in AROM+ hearts (dP/d tmax: 4,121 ± 255 vs. 4,992 ± 283 mmHg/s, P < 0.05) and associated with augmented Akt phosphorylation, consistent with a suppressor action of estrogen on contractility. Ischemic contracture was attenuated in AROM+ hearts (43 ± 3 vs. 55 ± 4 mmHg, P < 0.05), yet AROM+ hearts were more arrhythmic in early reperfusion. At the end of 60 min of reperfusion, AROM+ systolic functional recovery was lower (left ventricular developed pressure: 39 ± 6 vs. 56 ± 5 %basal, P < 0.05) and diastolic dysfunction was accentuated (36 ± 4 vs. 24 ± 2 mmHg, P < 0.05). This is the first study to show that in vivo aromatase upregulation modulates basal cardiac performance and the response to ischemic stress. These data suggest that while chronic exposure to enhanced estrogenic influence may have benefits in limiting ischemic contracture severity, acute functional recovery in reperfusion is compromised. A temporally targeted, tissue-specific intervention combining aromatase treatment with inotropic support may offer therapeutic potential for men and women.

Endurance exercise attenuates cardiotoxicity induced by androgen deprivation and doxorubicin

Doxorubicin (DOX) is associated with cardiac dysfunction and irreversible testicular damage. Androgen deprivation therapy (ADT) is administered prior to DOX treatment to preserve testicular function. However, ADT may exacerbate DOX-induced cardiac dysfunction. Exercise is cardioprotective, but the effects of exercise on cardiac function during combined ADT and DOX treatment are currently unknown. In this study, male Sprague-Dawley rats were randomly assigned to experimental groups: control (CON), ADT, DOX, or ADT+DOX. Animals received ADT or control implants on days 1 and 29 of the 56-day protocol. Animals remained sedentary (SED) or engaged in treadmill endurance exercise (TM) beginning on day 1. On day 15, the animals received DOX at 1 mg·(kg body mass)(-1)·d(-1) by intraperitoneal injection for 10 consecutive days, or an equivalent volume of saline. On day 57, cardiac function was assessed in vivo and ex vivo. Animals treated with DOX alone, or with combined ADT+DOX, showed significant (P < 0.05) reductions in left ventricular developed pressure (-21% and -27%), maximal rate of pressure development (-29% and -32%), and maximal rate of pressure decline (25% and 31%), respectively when compared with the sedentary control animals. Endurance exercise training attenuated (P > 0.05) cardiac dysfunction associated with combined ADT+DOX treatment, indicating that exercise during simultaneous ADT+DOX treatment is cardioprotective.

Sex and sex hormones in cardiac stress--mechanistic insights

Important sex differences in the onset and characteristics of cardiovascular disease are evident, yet the mechanistic details remain unresolved. Men are more susceptible to cardiovascular disease earlier in life, though younger women who have a cardiovascular event are more likely to experience adverse outcomes. Emerging evidence is prompting a re-examination of the conventional view that estrogen is protective and testosterone a liability. The heart expresses both androgen and estrogen receptors and is functionally responsive to circulating sex steroids. New evidence of cardiac aromatase expression indicates local estrogen production may also exert autocrine/paracrine actions in the heart. Cardiomyocyte contractility studies suggest testosterone and estrogen have contrasting inotropic actions, and modulate Ca(2+) handling and transient characteristics. Experimentally, sex differences are also evident in cardiac stress responses. Female hearts are generally less susceptible to acute ischemic damage and associated arrhythmias, and generally are more resistant to stress-induced hypertrophy and heart failure, attributed to the cardioprotective actions of estrogen. However, more recent data show that testosterone can also improve acute post-ischemic outcomes and facilitate myocardial function and survival in chronic post-infarction. The myocardial actions of sex steroids are complex and context dependent. A greater mechanistic understanding of the specific actions of systemic/local sex steroids in different cardiovascular disease states has potential to lead to the development of cardiac therapies targeted specifically for men and women.

Females of childbearing age have a survival benefit after out-of-hospital cardiac arrest

BACKGROUND

There is controversy regarding the association between age and being female and survival to hospital discharge after out-of-hospital cardiac arrest (OHCA). We hypothesized that younger females (aged 12-49 years) would be independently associated with increased survival after OHCA when compared to other age and sex groups.

METHODS

We conducted a secondary analysis of prospectively collected data from 29 United States cities that participate in the Cardiac Arrest Registry to Enhance Survival (CARES). Patients were included if they were ≥12 years of age and had a documented resuscitation attempt from October 1, 2005 through December 31, 2009. Hierarchical multivariable logistic regression analyses were used to estimate the associations between age and sex groups and survival to hospital discharge.

RESULTS

Females were less likely to have a cardiac arrest in public, was witnessed, or was treatable with defibrillation. Females in the 12-49 year old age group had a similar proportion of survival to hospital discharge when compared to age-matched males (females 11.6% vs. males 11.2%), while males ≥50 years old were more likely to survive when compared to age matched females (females 6.9% vs. males 9.6%). Age stratified regression models demonstrated that 12-49 year old females had the largest association with survival to hospital discharge (OR 1.55, 95% CI 1.20-2.00), while females in the ≥50 year old age group had a smaller increased odds of survival to hospital discharge (OR 1.18, 95% CI 1.03-1.35), which only lasted until the age of 55 years (OR 1.12, 95% CI 0.97-1.29).

CONCLUSIONS

Younger aged females were associated with increased odds of survival despite being found with poorer prognostic arrest characteristics.

Testosterone metabolites mediate its effects on myocardial damage induced by ischemia/reperfusion in male Wistar rats

The role of testosterone in cardiovascular (CV) homeostasis is in controversy, and the exact effects of testosterone on the cardiovascular system remain poorly understood. Testosterone is metabolized by aromatase into 17β-estradiol and by 5α-reductase into dihydrotestosterone (DHT). Thus, identification of these metabolites in the heart may help to explain the controversy regarding the cardiovascular effects of testosterone. We analyzed the expression patterns of these testosterone-metabolizing enzymes and assessed the effect of its enzymatic activity inhibition on ischemia (40 min)/reperfusion (4h, I/R) via the left anterior descendent coronary artery in intact and gonadectomized male rats. Myocardial damage was measured as percentage of infarcted area vs. area at risk. Aromatase and 5α-reductase protein expression was found in the left ventricle of intact and orchidectomized rats. Exogenous testosterone had no effect on I/R induced myocardial damage in intact male rats, meanwhile exogenous testosterone protects against I/R injury in orchidectomized rats. However, enzymatic inhibition of aromatase increased myocardial damage in the presence of testosterone, while enzymatic inhibition of 5α-reductase significantly decreased the level of myocardial damage. Our results also showed that sub-chronic inhibition of 5α-reductase resulted in myocardial protection in both groups. Furthermore, in orchidectomized and intact male rats IV treatment with DHT induces a significant increase in the myocardial damage induced by I/R. Thus, the effect of testosterone on cardiovascular pathophysiology could be related, at least in part to changes in the balance of testosterone 5α-reduction and aromatization.

Low-dose bisphenol A and estrogen increase ventricular arrhythmias following ischemia-reperfusion in female rat hearts

Bisphenol A (BPA) is an environmental estrogenic endocrine disruptor that may have adverse health impacts on a range of tissue/systems. In previous studies, we reported that BPA rapidly promoted arrhythmias in female rodent hearts through alteration of myocyte calcium handling. In the present study we investigated the acute effects of BPA on ventricular arrhythmias and infarction following ischemia-reperfusion in rat hearts. Rat hearts were subjected to 20 min of global ischemia followed by reperfusion. In female, but not male hearts, acute exposure to 1 nM BPA, either alone or combined with 1 nM 17β-estradiol (E2), during reperfusion resulted in a marked increase in the duration of sustained ventricular arrhythmias. BPA plus E2 increased the duration ventricular fibrillation, and the duration of VF as a fraction of total duration of sustained ventricular arrhythmia. The pro-arrhythmic effects of estrogens were abolished by MPP combined with PHTPP, suggesting the involvements of both ERα and ERβ signaling. In contrast to their pro-arrhythmic effects, BPA and E2 reduced infarction size, agreeing with previously described protective effect of estrogen against cardiac infarction. In conclusion, rapid exposure to low dose BPA, particularly when combined with E2, exacerbates ventricular arrhythmia following IR injury in female rat hearts.

A low-dose atorvastatin and losartan combination directly improves aortic ring relaxation and diminishes ischaemic-reperfusion injury in isolated rat hearts

Background

The cardiovascular pleiotropic effects of statins and angiotensin receptor blockers (ARBs) could be of interest for innovative preventive approaches. We aimed to investigate whether low-dose atorvastatin and losartan, separately not possessing protective cardiovascular pleiotropic effects, express them when combined.

Material/Methods

Forty-five adult male Wistar rats were anaesthetized and their thoracic aortas and hearts were isolated. Relaxation of aortic rings, coronary flow rate and the extent of myocardial ischaemic-reperfusion injury were measured. Different concentrations (0.01, 0.1, 1.0 μM) of atorvastatin and losartan added to a perfusion medium were first tested. The separate drugs, which were ineffective, were then combined at the same concentrations and the concentration was tested in the same model.

Results

Low concentrations of atorvastatin or losartan (0.1 and 1 μM, respectively) produced no effects in isolated aorta. However, surprisingly, when these drug concentrations were combined, a significantly improved endothelium-dependent relaxation of the thoracic aorta was observed. Similarly, when combining individually ineffective concentrations of atorvastatin or losartan (0.01 and 0.1 μM, respectively), significantly increased coronary flow and a decreased extent of myocardial injury were observed. By using a nitric oxide-synthase inhibitor, we demonstrated that the vasodilatory effects obtained were nitric oxide-dependent. The degree of effectiveness by the combination was comparable to that obtained by 10-fold (atorvastatin) or 100-fold (losartan) higher concentrations of the separate drugs.

Conclusions

Our results revealed that remarkable additive/synergistic effects exist between low-doses of a statin (atorvastatin) and an ARB (losartan), resulting in important cardiovascular protection. This new concept could be valuable in cardiovascular prevention.

Cardiovascular effects induced by polymeric 3-alkylpyridinium salts from the marine sponge Reniera sarai

Water-soluble polymeric 3-alkylpyridinum salts (poly-APS), isolated from the marine sponge Reniera sarai, are natural products with promising biomedical applications. However, their ability to form non-specific cell membrane pores raises safety issues. Therefore, the aim of the present study was to investigate the direct toxic effects of poly-APS on the cardiovascular system. To study the impact of poly-APS toxicodynamics on vascular function, the relaxation and contraction responses of isolated rat thoracic aortas incubated in poly-APS solutions (0.01-10 μM) were tested. In addition, cardiac toxicity was studied by measuring coronary flow, lactate dehydrogenase release rate, left ventricular pressure, heart rate, and the duration of arrhythmias in isolated rat hearts perfused with poly-APS (0.001-1 μM). Poly-APS diminished endothelium-dependent relaxation and contraction in a concentration- and time-dependent manner. Endothelial function was affected earlier and to a greater extent than contractile responses. Likewise, in isolated hearts the most evident cardiotoxic effects were observed after perfusion with the highest concentration (1 μM) of poly-APS: compared to the control group the coronary flow and heart rate were diminished by 2.2- and 1.8-fold, while lactate dehydrogenase release rate and left ventricular pressure were increased by 7.8- and 2.2-fold (all P < 0.001). Further, poly-APS had evident proarrhythmogenic activity in a concentration-dependent manner. However, in the low concentration range (1-10 nM) poly-APS showed only minor toxicity. Our results confirmed the direct toxic effects of poly-APS on the rat cardiovascular system. Therefore, it seems reasonable to conclude that the use of poly-APS as therapeutic adjuvants has limited safety margins.

Low-dose atorvastatin, losartan, and particularly their combination, provide cardiovascular protection in isolated rat heart and aorta

Statins and angiotensin receptor blockers at therapeutic doses have beneficial cardiovascular effects, which can be applied for cardiovascular protection. We explored whether low doses of atorvastatin, losartan, and particularly their combination, possess important pleiotropic vasodilatory effects. Wistar rats were treated daily with low-dose atorvastatin (2 mg/kg, n = 15), low-dose losartan (5 mg/kg, n = 15), their combination (n = 15), or saline (n = 15). After 4, 6, or 8 weeks the animals were anesthetized, blood samples taken, and their hearts and thoracic aortas isolated. Two kinds of experiments were performed: the measurement of coronary flow rate after ischemia/reperfusion myocardial injury and endothelium-dependent relaxation of thoracic aorta. In both models, maximal vasodilation activity was obtained in rats treated for 6 weeks. In the ischemia/reperfusion myocardial injury model, coronary flow increased (atorvastatin or losartan 1.9-fold, P < 0.01; combination 2.4-fold, P < 0.001) compared with controls. In the thoracic aorta model, endothelium-dependent relaxation significantly increased only in the combination group compared with the control group (up to 1.4-fold; P < 0.01). Simultaneously, we detected increased anti-inflammatory activity and increased nitric oxide concentration, but no changes in lipids and blood pressure. In a rat model we showed important vasodilatory activity of low-dose atorvastatin, losartan, and particularly their combination. The effects of the low-dose combination were accompanied by, and probably at least partly achieved by, anti-inflammatory and nitric oxide pathways. Overall, these results could be valuable for the development of new vascular protective strategies focusing on a low-dose regimen of statins and sartans, and particularly their combination.

The effects of testosterone on intestinal ischemia/reperfusion in rats

ABSTRACT Ischemic injury to the gut is believed to occur in many serious clinical conditions. Our aim was to investigate the postischemia/reperfusion (I/R) effects of exogenously administered testosterone on the intestines of normal and orchiectomized rats.Forty-eight rats were divided into eight groups of six animals: (1) Sham-operated control group; (2) Sham-operated + testosterone-treated group; (3) I/R group: Rats were subjected to the surgical procedures and underwent intestinal ischemia for 60 min followed by reperfusion for 60 min; (4) I/R + testosterone-treated group: Rats were subjected to the surgical procedures and received testosterone 100 mg/kg (i.p.); (5) I/R + orchiectomy group: Rats were subjected to the surgical procedures as well as orchiectomy; (6) orchiectomy group: Rats were subjected to the surgical procedures as well as orchiectomy; (7) orchiectomy + testosterone-treated group: Rats were subjected to the surgical procedures as well as orchiectomy and received testosterone 100 mg/kg (i.p.); and (8) I/R + orchiectomy + testosterone-treated group. The histological findings of this study paralleled the observed degree of lipid peroxidation (LPO) and protein oxidation. Intestinal mucosal injury was extensive in the I/R, I/R + orchiectomy, and I/R + orchiectomy + testosterone groups, but was less in the I/R + testosterone group. Histopathological injury also paralleled the degree of oxidative stress. Apoptotic enterocytes were more numerous in the I/R, I/R + orchiectomy, and I/R + orchiectomy + testosterone groups. Administration of testosterone in the presence of testes significantly protected intestinal tissue against I/R mucosal injuries, while administration of testosterone in the absence of testes did not significantly protect intestinal tissue against I/R mucosal injuries.

Both Mitochondrial KATP Channel Opening and Sarcolemmal KATP Channel Blockage Confer Protection Against Ischemia/Reperfusion-Induced Arrhythmia in Anesthetized Male Rats

Aim: This study was performed to assess the effect of selective sarcolemmal adenosine triphosphate (ATP)-sensitive K+ channel (KATP) inhibition and the mitochondrial KATP channel activation on ischemia and reperfusion (I/R)-induced arrhythmias in different gender of rats. We compared the effect of a selective sarcolemmal KATP channel blocker HMR 1098, a selective mitochondrial KATP channel opener diazoxide, a nonselective KATP channel opener pinacidil, and the combination of pinacidil with HMR 1098 on the incidence and duration of ventricular arrhythmias in 2 groups: anesthetized males (n = 31) and females (n = 31). Main Methods: Ischemia and reperfusion was produced by occluding the left main coronary artery of Sprague-Dowley rats for 6 minutes followed by re-opening of the artery for 6 minutes. Key Findings: The arrhythmia score and the duration of arrhythmias were significantly reduced by HMR 1098, diazoxide, and pinacidil in male rats. The combination of the pinacidil with HMR 1098 did not change the antiarrhythmic effect of pinacidil. The duration of arrhythmas was shorter in females than that in the corresponding males. Drug treatments were not effective in decreasing arrhythmias in female groups to the same extent as in the male group. However, the mitochondrial K ATP channel activation that is provided by the combination of pinacidil with HMR 1098 significantly decreased the total length of arrhythmias in females. Significance: Results of the current study indicate that both mitochondrial KATP channel activation and sarcolemmal KATP channel inhibition exert antiarrhythmic action in male rats. The antiarrhythmic effect of pinacidil is not depend on the sarcolemmal KATP channel opening. These results also indicate that KATP channel modulators show no discernable effect in female rats due to the already low incidence of arrhythmias in females.

Sex influences the susceptibility to reperfusion-induced sustained ventricular tachycardia and β-adrenergic receptor blockade in conscious rats

Reperfusion after a brief period of cardiac ischemia can lead to potentially lethal arrhythmias. Importantly, there are sex-related differences in cardiac physiology and in the types and severity of cardiac arrhythmias. Therefore, we tested the hypothesis that gonadal hormones influence the susceptibility to reperfusion-induced sustained ventricular tachycardia (VT), as well as the response to β-adrenergic receptor blockade. Male and female intact and gonadectomized rats were instrumented, and arterial pressure, temperature, ECG, and cardiac output were recorded. In addition, a snare was placed around the left main coronary artery. Tension was applied to the snare for determination of susceptibility to sustained VT produced by 3 min of occlusion and reperfusion of the left main coronary artery in conscious rats. Reperfusion culminated in sustained VT in 77% (10 of 13 susceptible) of female rats and 56% (9 of 16 susceptible) of male rats ( P > 0.05, male vs. female). β-Adrenergic receptor blockade prevented sustained VT in females only [1 of 9 susceptible females (11%) vs. 6 of 9 susceptible males (67%), P < 0.05]. Ovariectomy did not significantly reduce the susceptibility to reperfusion arrhythmias [5 of 9 susceptible (56%)]. In sharp contrast, orchidectomy significantly increased the susceptibility to reperfusion arrhythmias [9 of 9 susceptible (100%)]. Finally, β-adrenergic receptor blockade prevented sustained VT in ovariectomized females [0 of 4 susceptible (0%)] and orchidectomized males [0 of 7 susceptible (0%)], but the protective effect of β-blockade was due to a reduction in heart rate in males only. Thus gonadal hormones influence the susceptibility to reperfusion-induced arrhythmias, as well as the effects and mechanisms of β-adrenergic receptor blockade.