Sympathomimetic Effects of Acute E-Cigarette Use: Role of Nicotine and Non-Nicotine Constituents

Increased PHLPP1 expression through ERK-4E-BP1 signaling axis drives nicotine induced oxidative stress related damage of cardiomyocytes

Nicotine, a key constituent of tobacco/electronic cigarettes causes cardiovascular injury and mortality. Nicotine is known to induce oxidative stress and mitochondrial dysfunction in cardiomyocytes leading to cell death. However, the underlying mechanisms remain unclear. Pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) is a member of metal-dependent protein phosphatase (PPM) family and is known to dephosphorylate several AGC family kinases and thereby regulate a diverse set of cellular functions including cell growth, survival, and death. Our lab has previously demonstrated that PHLPP1 removal reduced cardiomyocyte death and cardiac dysfunction following injury. Here, we present a novel finding that nicotine exposure significantly increased PHLPP1 protein expression in the adolescent rodent heart. Building upon our in vivo finding, we determined the mechanism of PHLPP1 expression in cardiomyocytes. Nicotine significantly increased PHLPP1 protein expression without altering PHLPP2 in cardiomyocytes. In cardiomyocytes, nicotine significantly increased NADPH oxidase 4 (NOX4), which coincided with increased reactive oxygen species (ROS) and increased cardiomyocyte apoptosis which were dependent on PHLPP1 expression. PHLPP1 expression was both necessary and sufficient for nicotine induced mitochondrial dysfunction. Mechanistically, nicotine activated extracellular signal-regulated protein kinases (ERK1/2) and subsequent eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) to increase PHLPP1 protein expression. Inhibition of protein synthesis with cycloheximide (CHX) and 4EGI-1 abolished nicotine induced PHLPP1 protein expression. Moreover, inhibition of ERK1/2 activity by U0126 significantly blocked nicotine induced PHLPP1 expression. Overall, this study reveals a novel mechanism by which nicotine regulates PHLPP1 expression through ERK-4E-BP1 signaling axis to drive cardiomyocyte injury.

Nicotine Impairs Smooth Muscle cAMP Signaling and Vascular Reactivity

OBJECTIVE

This study aimed to determine nicotine's impact on receptor-mediated cyclic adenosine monophosphate (cAMP) synthesis in vascular smooth muscle (VSM). We hypothesize that nicotine impairs β adrenergic-mediated cAMP signaling in VSM, leading to altered vascular reactivity.

METHODS

The effects of nicotine on cAMP signaling and vascular function were systematically tested in aortic VSM cells and acutely isolated aortas from mice expressing the cAMP sensor TEpacVV (Camper), specifically in VSM (e.g., CamperSM).

RESULTS

Isoproterenol (ISO)-induced β-adrenergic production of cAMP in VSM was significantly reduced in cells from second-hand smoke (SHS)-exposed mice and cultured wild-type VSM treated with nicotine. The decrease in cAMP synthesis caused by nicotine was verified in freshly isolated arteries from a mouse that had cAMP sensor expression in VSM (e.g., CamperSM mouse). Functionally, the changes in cAMP signaling in response to nicotine hindered ISO-induced vasodilation, but this was reversed by immediate PDE3 inhibition.

CONCLUSIONS

These results imply that nicotine alters VSM β adrenergic-mediated cAMP signaling and vasodilation, which may contribute to the dysregulation of vascular reactivity and the development of vascular complications for nicotine-containing product users.

Direct health implications of e-cigarette use: a systematic scoping review with evidence assessment

Background

E-cigarettes are often marketed as a less harmful alternative to traditional tobacco cigarettes. Despite their popularity, the evidence regarding their effects on human health remains unclear and is filled with complexities.

Objectives

This systematic review aims to elucidate the direct effects of electronic cigarette use on human health, carefully distinguishing between the specific characteristics of the populations studied.

Methodology

Adhering to the PRISMA guidelines, we conducted a comprehensive search in PubMed/Medline, Web of Science, Scopus, and Google Scholar databases without date restrictions, including articles in both Spanish and English. This approach enabled the identification and analysis of primary studies to understand the direct effect of electronic cigarettes on human health.

Results

A total of 33 studies were included that evaluated cardiovascular, pulmonary, renal, weight and fertility effects. Only five studies analyzed e-cigarettes in healthy populations and seven studies compared healthy individuals against smokers. The effects evaluated on smokers or former tobacco smokers were apparently positive, however, among healthy individuals, increased heart rate, mean arterial pressure, oxidative stress, alteration of respiratory epithelial cells and increased airflow resistance were found.

Conclusion

Smokers or former smokers who switch to e-cigarettes may reduce their exposure to carcinogens and lower their risk of developing severe health issues associated with conventional smoking. However, in healthy individuals who have never smoked traditional cigarettes, the use of e-cigarettes introduces several cardiovascular and respiratory adverse effects. These findings suggest that while e-cigarettes can be a strategic harm reduction tool for smokers, they are not a safe option for non-smokers.

Formaldehyde and the Transient Receptor Potential Ankyrin-1 Contribute to Electronic Cigarette Aerosol-induced Endothelial Dysfunction in Mice

Electronic Nicotine Delivery Systems (ENDS) aerosol exposures can induce endothelial dysfunction (ED) in healthy young humans and animals. Thermal degradation of ENDS solvents, propylene glycol and vegetable glycerin (PG: VG), generates abundant formaldehyde (FA) and other carbonyls. Because FA can activate the transient receptor potential ankyrin-1 (TRPA1) sensor, we hypothesized that FA in ENDS aerosols provokes TRPA1-mediated changes that include ED and 'respiratory braking' - biomarkers of harm. To test this, wild-type (WT) and TRPA1-null mice were exposed by inhalation to either filtered air, PG: VG-derived aerosol, or formaldehyde (FA, 5 ppm). Short-term exposures to PG: VG and FA induced ED in female WT but not in female TRPA1-null mice. Moreover, acute exposures to PG: VG and FA stimulated respiratory braking in WT but not in TRPA1-null female mice. Urinary metabolites of FA (ie, N  -1,3-thiazolidine-4-carboxylic acid, TCA; N  -1,3-thiazolidine-4-carbonyl glycine, TCG) and monoamines were measured by LC-MS/MS. PG: VG and FA exposures significantly increased urinary excretion of both TCA and TCG in both WT and TRPA1-null mice. To confirm that inhaled FA directly contributed to urinary TCA, mice were exposed to isotopic 13C-FA gas (1 ppm, 6 h).13C-FA exposure significantly increased the urine level of 13C-TCA in the early collection (0-3 h) supporting a direct relationship between inhaled FA and TCA. Collectively, these data suggest that ENDS use may increase CVD risk dependent on FA, TRPA1, and catecholamines, yet independently of either nicotine or flavorants. This study supports that levels of FA in ENDS-derived aerosols should be lowered to mitigate CVD risk in people who use ENDS.

Arrhythmogenic effects of acute electronic cigarette compared to tobacco cigarette smoking in people living with HIV

The leading cause of death in people living with HIV (PLWH) is cardiovascular disease, and the high prevalence of tobacco cigarette (TC) smoking is a major contributor. Switching to electronic cigarettes (ECs) has been promoted as a harm reduction strategy. We sought to determine if acute EC compared to TC smoking had less harmful effects on arrhythmogenic risk factors including acute changes in hemodynamics, heart rate variability (HRV), and ventricular repolarization (VR). In PLWH who smoke, changes in hemodynamics, HRV, and VR were compared pre/post acutely using an EC, TC, or puffing on an empty straw on different days in random order, in a crossover study. Thirty-seven PLWH (36 males, mean age 40.5 ± 9.1 years) participated. Plasma nicotine was greater after TC versus EC use (10.12 ± 0.96 vs. 6.18 ± 0.99 ng/mL, respectively, p = 0.004). HR increased significantly, and similarly, after acute EC and TC smoking compared to control. Changes in HRV that confer increased cardiac risk (LF/HF ratio) were significantly smaller after acute EC versus TC use, consistent with a harm reduction effect. In a post-hoc analysis of PLWH with and without positive concurrent recreational drug use as indicated by point of care urine toxicology testing, this differential effect was only seen in PLWH not currently using recreational drugs. Changes in VR were not different among the three exposures. In PLWH who smoke, EC compared to TC smoking resulted in smaller adverse changes in HRV. This differential effect was accompanied by a smaller increase in plasma nicotine, and was negated by concurrent recreational drug use. Additional studies are warranted in this vulnerable population disproportionately affected by tobacco-related health disparities.

Chronic nicotine exposure is associated with electrophysiological and sympathetic remodeling in the intact rabbit heart

Nicotine is the primary addictive component of tobacco products. Through its actions on the heart and autonomic nervous system, nicotine exposure is associated with electrophysiological changes and increased arrhythmia susceptibility. To assess the underlying mechanisms, we treated rabbits with transdermal nicotine (NIC, 21 mg/day) or control (CT) patches for 28 days before performing dual optical mapping of transmembrane potential (RH237) and intracellular Ca2+ (Rhod-2 AM) in isolated hearts with intact sympathetic innervation. Sympathetic nerve stimulation (SNS) was performed at the first to third thoracic vertebrae, and β-adrenergic responsiveness was additionally evaluated following norepinephrine (NE) perfusion. Baseline ex vivo heart rate (HR) and SNS stimulation threshold were higher in NIC versus CT (P = 0.004 and P = 0.003, respectively). Action potential duration alternans emerged at longer pacing cycle lengths (PCL) in NIC versus CT at baseline (P = 0.002) and during SNS (P = 0.0003), with similar results obtained for Ca2+ transient alternans. SNS shortened the PCL at which alternans emerged in CT but not in NIC hearts. NIC-exposed hearts tended to have slower and reduced HR responses to NE perfusion, but ventricular responses to NE were comparable between groups. Although fibrosis was unaltered, NIC hearts had lower sympathetic nerve density (P = 0.03) but no difference in NE content versus CT. These results suggest both sympathetic hypoinnervation of the myocardium and regional differences in β-adrenergic responsiveness with NIC. This autonomic remodeling may contribute to the increased risk of arrhythmias associated with nicotine exposure, which may be further exacerbated with long-term use.NEW & NOTEWORTHY Here, we show that chronic nicotine exposure was associated with increased heart rate, increased susceptibility to alternans, and reduced sympathetic electrophysiological responses in the intact rabbit heart. We suggest that this was due to sympathetic hypoinnervation of the myocardium and diminished β-adrenergic responsiveness of the sinoatrial node following nicotine treatment. Though these differences did not result in increased arrhythmia propensity in our study, we hypothesize that prolonged nicotine exposure may exacerbate this proarrhythmic remodeling.

Comparison of Acute Effects of E-cigarettes With and Without Nicotine and Tobacco Cigarettes on Hemodynamic and Endothelial Parameters: A Systematic Review and Meta-analysis

INTRODUCTION

Smoke from traditional cigarettes and e-cigarette aerosols have distinct chemical compositions that may impact blood pressure (BP) and heart rate (HR) differently.

AIMS

This study compared the impact of nicotine-containing e-cigarettes (EC+) versus nicotine-free (EC-) on BP, HR and endothelial markers, and assessed if EC+ posed fewer risks than tobacco cigarettes (TC).

METHODS

Electronic databases were searched from inception until November 2023 for studies reporting changes in systolic and diastolic BP (SBP, DBP) and HR and endothelial parameters before and after the use of EC+, EC- and TC. Data were analyzed using weighted mean differences (WMDs) and 95% confidence intervals (CIs).

RESULTS

Fifteen studies (n = 752) were included in our meta-analysis. We demonstrate that EC+ significantly increased systolic BP (WMD = 3.41, 95% CI [0.1,6.73], p = 0.04], diastolic BP (WMD = 3.42, 95% CI [1.75, 5.09]; p < 0.01], and HR (WMD = 5.36 BPM, 95% CI [1.87, 8.85]; p < 0.01) compared to EC-. However, EC+ was observed to cause less detrimental effect on SBP (WMD = - 4.72 mmHg, 95% CI [- 6.58, - 2.86], p < 0.01), and HR (WMD = - 3.11 BPM, 95% CI [- 4.54, - 1.68]; p < 0.01) as compared to TC with no difference on DBP (WMD = - 1.14 mmHg, 95% CI [- 2.38, 0.1]; p = 0.07). EC+ also led to greater deterioration of endothelial parameters as compared to EC- but to a lesser degree as compared to TC.

CONCLUSION

EC+ shows greater impairment in hemodynamic and endothelial parameters than EC- but less than TC. Additional studies are needed to evaluate prolonged effects of EC use.

Addressing Cardiovascular Toxicity Risk of Electronic Nicotine Delivery Systems in the Twenty-First Century: "What Are the Tools Needed for the Job?" and "Do We Have Them?"

Cigarette smoking is positively and robustly associated with cardiovascular disease (CVD), including hypertension, atherosclerosis, cardiac arrhythmias, stroke, thromboembolism, myocardial infarctions, and heart failure. However, after more than a decade of ENDS presence in the U.S. marketplace, uncertainty persists regarding the long-term health consequences of ENDS use for CVD. New approach methods (NAMs) in the field of toxicology are being developed to enhance rapid prediction of human health hazards. Recent technical advances can now consider impact of biological factors such as sex and race/ethnicity, permitting application of NAMs findings to health equity and environmental justice issues. This has been the case for hazard assessments of drugs and environmental chemicals in areas such as cardiovascular, respiratory, and developmental toxicity. Despite these advances, a shortage of widely accepted methodologies to predict the impact of ENDS use on human health slows the application of regulatory oversight and the protection of public health. Minimizing the time between the emergence of risk (e.g., ENDS use) and the administration of well-founded regulatory policy requires thoughtful consideration of the currently available sources of data, their applicability to the prediction of health outcomes, and whether these available data streams are enough to support an actionable decision. This challenge forms the basis of this white paper on how best to reveal potential toxicities of ENDS use in the human cardiovascular system-a primary target of conventional tobacco smoking. We identify current approaches used to evaluate the impacts of tobacco on cardiovascular health, in particular emerging techniques that replace, reduce, and refine slower and more costly animal models with NAMs platforms that can be applied to tobacco regulatory science. The limitations of these emerging platforms are addressed, and systems biology approaches to close the knowledge gap between traditional models and NAMs are proposed. It is hoped that these suggestions and their adoption within the greater scientific community will result in fresh data streams that will support and enhance the scientific evaluation and subsequent decision-making of tobacco regulatory agencies worldwide.

Nicotine Formulation Influences the Autonomic and Arrhythmogenic Effects of Electronic Cigarettes

INTRODUCTION

Evidence is mounting that electronic cigarette (e-cig) use induces cardiac sympathetic dominance and electrical dysfunction conducive to arrhythmias and dependent upon nicotine. A variety of nicotine types and concentrations are available in e-cigs, but their relative cardiovascular effects remain unclear. Here we examine how different nicotine forms (racemic, free base, and salt) and concentrations influence e-cig-evoked cardiac dysfunction and arrhythmogenesis and provide a mechanism for nicotine-salt-induced autonomic imbalance.

METHODS

ECG-telemetered C57BL/6J mice were exposed to filtered air (FA) or e-cig aerosols from propylene glycol and vegetable glycerin solvents either without nicotine (vehicle) or with increasing nicotine concentrations (1%, 2.5%, and 5%) for three 9-minute puff sessions per concentration. Spontaneous ventricular premature beat (VPB) incidence rates, heart rate, and heart rate variability (HRV) were compared between treatments. Subsequently, to test the role of β1-adrenergic activation in e-cig-induced cardiac effects, mice were pretreated with atenolol and exposed to either FA or 2.5% nicotine salt.

RESULTS

During puffing and washout phases, ≥2.5% racemic nicotine reduced heart rate and increased HRV relative to FA and vehicle controls, indicating parasympathetic dominance. Relative to both controls, 5% nicotine salt elevated heart rate and decreased HRV during washout, suggesting sympathetic dominance, and also increased VPB frequency. Atenolol abolished e-cig-induced elevations in heart rate and declines in HRV during washout, indicating e-cig-evoked sympathetic dominance is mediated by β1-adrenergic stimulation.

CONCLUSIONS

Our findings suggest that inhalation of e-cig aerosols from nicotine-salt-containing e-liquids could increase the cardiovascular risks of vaping by inducing sympathetic dominance and cardiac arrhythmias.

IMPLICATIONS

Exposure to e-cig aerosols containing commercially relevant concentrations of nicotine salts may increase nicotine delivery and impair cardiac function by eliciting β1-adrenoceptor-mediated sympathoexcitation and provoking ventricular arrhythmias. If confirmed in humans, our work suggests that regulatory targeting of nicotine salts through minimum pH standards or limits on acid additives in e-liquids may mitigate the public health risks of vaping.

The potential health effects associated with electronic-cigarette

A good old gateway theory that electronic-cigarettes (e-cigarettes) are widely recognized as safer tobacco substitutes. In actuality, demographics also show that vaping cannibalizes smoking, the best explanation of the data is the "common liability". However, the utilization of e-cigarette products remains a controversial topic at present. Currently, there has been a widespread and substantial growth in e-cigarette use worldwide owing to their endless new flavors and customizable characteristics. Furthermore, e-cigarette has grown widespread among smokers as well as non-smokers, including adolescents and young adults. And some studies have shown that e-cigarette users are at greater risk to start using combustible cigarettes while e-cigarettes use was also observed the potential benefits to people who want to quit smoking or not. Although it is true that e-cigarettes generally contain fewer toxic substances than combustible cigarettes, this does not mean that the chemical composition in e-cigarettes aerosols poses absolutely no risks. While concerns about toxic substances in e-cigarettes and their widespread use in the population are reasonable, it is also crucial to consider that e-cigarettes have been associated with the potential for promoting smoking cessation and the clinically relevant improvements in users with smoking-related pathologies. Meanwhile, there is still short of understanding of the health impacts associated with e-cigarette use. Therefore, in this review, we discussed the health impacts of e-cigarette exposure on oral, nasal, pulmonary, cardiovascular systems and brain. We aspire for this review to change people's previous perceptions of e-cigarettes and provide them with a more balanced perspective. Additionally, we suggest appropriate adjustments on regulation and policy for e-cigarette to gain greater public health benefits.

The Rising Use of E-Cigarettes: Unveiling the Health Risks and Controversies

The use of e-cigarettes has tremendously increased in recent times due to the widespread availability of e-cigarettes in diverse flavors, reduced cost compared to regular cigarettes, and misconception of being comparatively safe, which have led to around 2.55 million US middle and high school students smoking e-cigarettes. These devices use a nicotine-rich liquid, which is aerosolized electronically, producing vapors that may also include hazardous chemicals and heavy metals. E-cigarettes are associated with e-cigarette or vaping-associated lung injury, which presents as an acute respiratory ailment mirroring various pulmonary diseases. Additionally, it causes endothelial dysfunction, alters blood lipid profile by elevating circulating levels of low-density lipoprotein cholesterol, increases sympathetic tone, and is found to correlate with arterial stiffening, hence negatively affecting respiratory, cardiovascular, and overall health. We aim to provide a comprehensive analysis of the data on e-cigarettes and their harmful effects on health in comparison to conventional cigarette use by highlighting the pathophysiology of e-cigarette-induced adverse effects and critically analyzing the data both in favor and against its use. Our review concludes that no matter how much nicotine an e-cigarette contains, evidence shows that using it increases the risk of cardiovascular disease, albeit maybe not as much as smoking regular tobacco. Nonetheless, it is crucial to note that the long-term effects of e-cigarette usage are still not fully understood, and existing data have provided opposing viewpoints.

Acute cardiovascular effects of 4th generation electronic cigarettes and combusted cigarettes: implications for harm reduction

The health consequences associated with using electronic cigarettes (ECs) are of great public interest because of their potential role in smoking cessation. In 110 participants, including 41 nonusers, 34 people who exclusively use ECs (EC group), and 35 people who smoke tobacco cigarettes (TCs) including 12 dual users (collectively called the TC-D group), the heart rate (HR), blood pressure (BP), and heart rate variability (HRV) were compared at baseline. People in the EC or the TC-D groups were also compared after using a 4th generation EC with or without nicotine, a TC with or without nicotine (TC-D group only), and a straw-control. Baseline HR, BP, and HRV parameters were not different among the EC, the TC-D, and nonuser groups. In people who exclusively use ECs, acute nicotine-EC use increased HR and BP, and produced changes in HRV patterns suggestive of increased cardiac sympathetic influence. In people in the TC-D group, BP increased similarly after acutely smoking a nicotine-TC or a nicotine-EC. However, the increase in HR was significantly greater after smoking a TC compared with the nicotine-EC despite similar acute increases in plasma nicotine. Overall, all exposures containing nicotine significantly increased HR and BP in both cohorts when compared with non-nicotine exposures. Since acute EC use 1) produces an abnormal HRV pattern associated with increased cardiac sympathetic tone in people who chronically use ECs, and 2) similar hemodynamic increases compared with acute TC smoking in people who chronically smoke TCs including dual users, the role of ECs as part of a harm reduction strategy is questioned.NEW & NOTEWORTHY We found that nicotine, not the non-nicotine constituents in tobacco cigarette (TC) or electronic cigarette (EC) emissions, may be the instigator of the acute, potentially adverse, changes in hemodynamics and heart rate variability (HRV) that were recorded several minutes after tobacco product use. Furthermore, acute EC use produced an abnormal HRV pattern associated with increased cardiac risk in people who chronically smoke ECs and produced similar hemodynamic increases compared with acute TC use in people who chronically smoke TCs, including people who are dual users.

Chronic nicotine exposure is associated with electrophysiological and sympathetic remodeling in the intact rabbit heart

Nicotine is the primary addictive component in tobacco products. Through its actions on the heart and autonomic nervous system, nicotine exposure is associated with electrophysiological changes and increased arrhythmia susceptibility. However, the underlying mechanisms are unclear. To address this, we treated rabbits with transdermal nicotine (NIC, 21 mg/day) or control (CT) patches for 28 days prior to performing dual optical mapping of transmembrane potential (RH237) and intracellular Ca 2+ (Rhod-2 AM) in isolated hearts with intact sympathetic innervation. Sympathetic nerve stimulation (SNS) was performed at the 1 st - 3 rd thoracic vertebrae, and β-adrenergic responsiveness was additionally evaluated as changes in heart rate (HR) following norepinephrine (NE) perfusion. Baseline ex vivo HR and SNS stimulation threshold were increased in NIC vs. CT ( P = 0.004 and P = 0.003 respectively). Action potential duration alternans emerged at longer pacing cycle lengths (PCL) in NIC vs. CT at baseline ( P = 0.002) and during SNS ( P = 0.0003), with similar results obtained for Ca 2+ transient alternans. SNS reduced the PCL at which alternans emerged in CT but not NIC hearts. NIC exposed hearts also tended to have slower and reduced HR responses to NE perfusion. While fibrosis was unaltered, NIC hearts had lower sympathetic nerve density ( P = 0.03) but no difference in NE content vs. CT. These results suggest both sympathetic hypo-innervation of the myocardium and diminished β-adrenergic responsiveness with NIC. This autonomic remodeling may underlie the increased risk of arrhythmias associated with nicotine exposure, which may be further exacerbated with continued long-term usage.

NEW & NOTEWORTHY

Here we show that chronic nicotine exposure was associated with increased heart rate, lower threshold for alternans and reduced sympathetic electrophysiological responses in the intact rabbit heart. We suggest that this was due to the sympathetic hypo-innervation of the myocardium and diminished β- adrenergic responsiveness observed following nicotine treatment. Though these differences did not result in increased arrhythmia propensity in our study, we hypothesize that prolonged nicotine exposure may exacerbate this pro-arrhythmic remodeling.

Preliminary study on the E-liquid and aerosol on the neurobehavior of C. elegans

E-cigarettes, also known as electronic nicotine delivery systems (ENDS), are mainly used among adolescents and young adults. Similar to traditional cigarettes, different concentrations of nicotine are also added to E-cigarette's liquid (E-liquid), but due to the supplementation of chemicals such as propylene glycol (PG), vegetable glycerin (VG) and flavors, it is difficult to determine the risk after using E-cigarettes. And given to the specificity of the aerosol particle composition and atomization process of E-cigarettes, it is necessary to assess the neurotoxic effects of long-term E-cigarettes use. In this study, two commercial nicotine-containing (5%) and nicotine-free E-liquids were diluted to investigate the neurobehavioral changes and addictive tendencies of developing C. elegans after sub-chronic exposure to E-liquid. The results showed that sub-chronic exposure of E-liquid could lead to impaired growth and development of nematodes, abnormal general neuromotor behavior and advanced learning and memory behavior, and nicotine-containing E-liquid could also lead to increased addiction tendency of nematodes. Although the damage effect of nicotine free E-liquid is smaller than that of the nicotine-containing group, its toxic effect cannot be ignored. Further analysis of the neurotoxicity mechanism found that redox imbalance-mediated mitochondrial stress and aging may be important causes of E-liquid-induced biological damage. The biosafety of e-cigarette aerosols was also included in the assessment. The study found that the heated atomization process did not alter the E-liquid components, and E-cigarette aerosols still have the effect of interfering with the growth and development of nematodes and neurobehavior, and its addictive nature is also of concern. This study can provide new ideas for future studies on the neurotoxic effects and safety assessment of the E-cigarettes, and provide theoretical reference for the study on the injury mechanism of E-cigarettes.

Association of Electronic Cigarette Exposure on Cardiovascular Health: A Systematic Review and Meta-Analysis

Despite the growing use of electronic cigarettes (EC) in the Unites States, particularly among young people, and their perceived safety, current evidence suggests that EC usage may cause adverse clinical cardiovascular effects. Therefore, we aim to pool all studies evaluating the association of EC exposure with cardiovascular health. Medline, Cochrane CENTRAL, and Scopus were searched for studies from January 1, 2006 until December 31, 2022. Randomized and observational studies reporting cardiovascular outcomes, hemodynamic parameters, and biomarkers of platelet physiology, before and after acute or chronic EC exposure were pooled using a random-effects model. Overall, 27 studies (n = 863) were included. Heart rate increased significantly after acute EC exposure (weighted mean difference [WMD]: 0.76 bpm; 95% confidence interval [CI], 0.48, 1.03; P < 0.00001; I2 = 92%). Significant increases in systolic blood pressure (WMD: 0.28 mmHg; 95% CI, 0.06, 0.51; P = 0.01; I2 = 94%), diastolic blood pressure (WMD: 0.38 mmHg; 95% CI, 0.16, 0.60; P = 0.0006; I2 = 90%), and PWV (WMD: 0.38; 95% CI, 0.13, 0.63; P = 0.003; I2 = 100%) were also observed. Augmentation index increased significantly (SMD: 0.39; 95% CI, 0.11, 0.67; P = 0.007; I2 = 90%), whereas reduction in flow-mediated dilation (WMD: -1.48; 95% CI, -2.49, -0.47; P = 0.004; I2 = 45%) was observed. Moreover, significant rise in both soluble P-selectin (WMD: 4.73; 95% CI, 0.80, 8.66; P = 0.02; I2 = 98%) and CD40L (WMD: 1.14; 95% CI, 0.41, 1.87; P = 0.002; I2 = 79%) was observed. Our results demonstrate that smoking EC is associated with a significant increase in cardiovascular hemodynamic measures and biomarkers. Our findings can aid policymakers in making informed decisions regarding the regulation of EC to ensure public safety.

Cardiopulmonary Impact of Electronic Cigarettes and Vaping Products: A Scientific Statement From the American Heart Association

Vaping and electronic cigarette (e-cigarette) use have grown exponentially in the past decade, particularly among youth and young adults. Cigarette smoking is a risk factor for both cardiovascular and pulmonary disease. Because of their more limited ingredients and the absence of combustion, e-cigarettes and vaping products are often touted as safer alternative and potential tobacco-cessation products. The outbreak of e-cigarette or vaping product use-associated lung injury in the United States in 2019, which led to >2800 hospitalizations, highlighted the risks of e-cigarettes and vaping products. Currently, all e-cigarettes are regulated as tobacco products and thus do not undergo the premarket animal and human safety studies required of a drug product or medical device. Because youth prevalence of e-cigarette and vaping product use was as high as 27.5% in high school students in 2019 in the United States, it is critical to assess the short-term and long-term health effects of these products, as well as the development of interventional and public health efforts to reduce youth use. The objectives of this scientific statement are (1) to describe and discuss e-cigarettes and vaping products use patterns among youth and adults; (2) to identify harmful and potentially harmful constituents in vaping aerosols; (3) to critically assess the molecular, animal, and clinical evidence on the acute and chronic cardiovascular and pulmonary risks of e-cigarette and vaping products use; (4) to describe the current evidence of e-cigarettes and vaping products as potential tobacco-cessation products; and (5) to summarize current public health and regulatory efforts of e-cigarettes and vaping products. It is timely, therefore, to review the short-term and especially the long-term implications of e-cigarettes and vaping products on cardiopulmonary health. Early molecular and clinical evidence suggests various acute physiological effects from electronic nicotine delivery systems, particularly those containing nicotine. Additional clinical and animal-exposure model research is critically needed as the use of these products continues to grow.

Electronic Nicotine Delivery System: End to Smoking or Just a New Fancy Cigarette

Smoking and tobacco chewing are the predominant causes of oral cancer. Tobacco is the second-most widely consumed psychoactive substance. There are numerous ways to quit smoking, of which one is electronic cigarettes (e-cigarettes). E-cigarette use is a brand-new, global trend. E-cigarette is a battery-operated device that heats a liquid to create a vapor that the consumer inhales. Several countries have acknowledged that the first step toward electronic nicotine delivery system (ENDS) management is a precise classification of ENDS within the limits of current legislation. Countries have currently categorized ENDS into four generations. People's perceptions about tobacco products have altered recently as a consequence of the advertising of ENDS. The likelihood of starting to smoke cigarettes was four times higher in adolescents who used ENDS, and the probability of quitting was reduced and often prolonged in those who used ENDS. In addition, ENDS normalizes smoking-like actions including inhaling in and exhaling smoke. Adverse marketing via geographic locations and social media platforms, as well as nicotine's irreversible effects on growing adolescent and young adult brains that predispose individuals to addicted behaviors, may be responsible for their rising appeal among teenagers. Despite this, ENDS use has risen among young individuals who have never smoked and undoubtedly face more health risks than those who do not use ENDS. The oral cavity is the first to encounter ENDS in individuals and where it initially affects the human system. As a known contributor to cardiovascular diseases, neurological conditions, and cancers, nicotine seems to be a serious cause for concern. This review provides a concise summary of the research on the components, mode of action, applications, and effects of e-cigarettes on oral as well as systemic systems.

The cardiovascular consequences of electronic cigarette smoking: a narrative review

INTRODUCTION

E-cigarettes have emerged as a popular alternative to traditional tobacco smoking in recent years. Despite their growing popularity, concerns have arisen regarding the cardiovascular implications of e-cigarette use.

AREAS COVERED

This narrative review aims to highlight the latest evidence on the impact of e-cigarettes on cardiovascular health.

EXPERT OPINION

Numerous studies have demonstrated that e-cigarette use can lead to acute adverse cardiovascular effects. Inhalation of e-cigarette aerosols exposes users to a wide range of potentially harmful substances that have been implicated in critical pathophysiologic pathways of cardiovascular disease, namely endothelial dysfunction, oxidative stress, inflammation, sympathetic overdrive, and arterial stiffness. While long-term epidemiological studies specifically focusing on the cardiovascular effects of e-cigarettes are still relatively scarce, early evidence suggests a potential association between e-cigarette use and an increased risk of adverse cardiovascular events. However, it is essential to recognize that e-cigarettes are relatively new products, and the full extent of their long-term cardiovascular impact has not been fully elucidated. In the meantime, promoting tobacco cessation strategies that are evidence-based and regulated, along with rigorous monitoring of e-cigarette use patterns and associated health outcomes, are essential steps in safeguarding cardiovascular health in the face of this emerging public health challenge.

Nicotine and Microvascular Responses in Skeletal Muscle from Acute Exposure to Cigarettes and Vaping

Despite claims of safety or harm reduction for electronic cigarettes (E-cig) use (also known as vaping), emerging evidence indicates that E-cigs are not likely safe, or necessarily safer than traditional cigarettes, when considering the user's risk of developing vascular dysfunction/disease. E-cigs are different from regular cigarettes in that E-cig devices are highly customizable, and users can change the e-liquid composition (such as the base solution, flavors, and nicotine level). Since the effects of E-cigs on the microvascular responses in skeletal muscle are poorly understood, we used intravital microscopy with an acute (one-time 10 puff) exposure paradigm to evaluate the individual components of e-liquid on vascular tone and endothelial function in the arterioles of the gluteus maximus muscle of anesthetized C57Bl/6 mice. Consistent with the molecular responses seen with endothelial cells, we found that the peripheral vasoconstriction response was similar between mice exposed to E-cig aerosol or cigarette smoke (i.e., 3R4F reference cigarette); this response was not nicotine dependent, and endothelial cell-mediated vasodilation was not altered within this acute exposure paradigm. We also report that, regardless of the base solution component [i.e., vegetable glycerin (VG)-only or propylene glycol (PG)-only], the vasoconstriction responses were the same in mice with inhalation exposure to 3R4F cigarette smoke or E-cig aerosol. Key findings from this work reveal that some component other than nicotine, in inhaled smoke or aerosol, is responsible for triggering peripheral vasoconstriction in skeletal muscle, and that regardless of one's preference for an E-cig base solution composition (i.e., ratio of VG-to-PG), the acute physiological response to blood vessels appears to be the same. The data suggest that vaping is not likely to be 'safer' than smoking towards blood vessels and can be expected to produce and/or result in the same adverse vascular health outcomes associated with smoking cigarettes.

Characterization and Summarization of the Impact of Electronic Cigarettes on the Cardiovascular System: A Systematic Review and Meta-Analysis

Electronic cigarettes may increase the risk of long-term cardiovascular morbidity. To protect the heart, awareness should be raised of the risks and limits of E-cigarette aerosol exposure. Thus, this systematic review and meta-analysis assessed the cardiovascular risk of e-smoking. This systematic review was conducted by using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. We searched PubMed, Embase, Scopus, Web of Science, and Science Direct databases in December 2022 to identify studies investigating e-cigarettes' impact on the heart. The study was supported by meta-analysis and qualitative review. Out of the initial 493 papers, only 15 met the inclusion criteria and were included in the study. The cumulative number of participants in the myocardial infarction (MI) group was 85,420, and in the sympathetic groups in whom the systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), and heart rate (HR) were measured, were 332 cigarette smokers. The control group included the "never use," "non-smokers," and "never smoke." The pooled analysis showed a significant difference between the e-cigarette smokers and the control group regarding the risk of developing MI in former smokers (OR= 0.12; 95% CI: 0.01-1.72, P = 0.12) and never smoked (OR= 0.02; 95% CI: 0.00-0.44, P = 0.01) favoring the control group. The pooled analysis of the included studies showed a significant difference between the e-cigarette smokers with nicotine and the control group regarding the mean difference (MD) of the SBP (MD = 2.89; 95% CI: 1.94-3.84; P < 0.001), the DBP (MD = 3.10; 95% CI: 0.42-5.78; P = 0.02), the MBP (MD = 7.05; 95% CI: 2.70-1.40; P = 0.001), and HF (MD = 3.13; 95% CI: 0.96-5.29; P = 0.005) favoring the control group. We conclude that using e-cigarettes has a detrimental effect on cardiac health. The risk of severe cardiac conditions increases with e-cigarettes. Thus, vaping can do more harm than good. Consequently, the misleading notion that e-cigarettes are less harmful should be challenged.

Electronic Nicotine Delivery Systems and Cardiovascular/Cardiometabolic Health

The use of electronic nicotine delivery systems, specifically electronic cigarettes (e-cig), has risen dramatically within the last few years; the demographic purchasing these devices is now predominantly adolescents that are not trying to quit the use of traditional combustible cigarettes, but rather are new users. The composition and appearance of these devices has changed since their first entry into the market in the late 2000s, but they remain composed of a battery and aerosol delivery system that is used to deliver breakdown products of propylene glycol/vegetable glycerin, flavorings, and potentially nicotine or other additives. Manufacturers have also adjusted the type of nicotine that is used within the liquid to make the inhalation more palatable for younger users, further affecting the number of youth who use these devices. Although the full spectrum of cardiovascular and cardiometabolic consequences of e-cig use is not fully appreciated, data is beginning to show that e-cigs can cause both short- and long-term issues on cardiac function, vascular integrity and cardiometabolic issues. This review will provide an overview of the cardiovascular, cardiometabolic, and vascular implications of the use of e-cigs, and the potential short- and long-term health effects. A robust understanding of these effects is important in order to inform policy makers on the dangers of e-cigs use.

Current Evidence on Prevention of Atrial Fibrillation: Modifiable Risk Factors and the Effects of Risk Factor Intervention

Atrial fibrillation (AF) is one of the most encountered arrhythmias in clinical practice. It is also estimated that the absolute AF burden may increase by greater than 60% by 2050. It is inevitable that AF will become one of the largest epidemics in the world and may pose a major health problem for countries. Although AF rarely causes mortality in the acute period, it causes a significant increase in mortality and morbidity, including a fivefold increase in the risk of stroke, a twofold increase in dementia, and a twofold increase in myocardial infarction in the chronic period. Despite all the advances in the treatment of AF, it is better understood day by day that preventing AF may play a key role in reducing AF and its related complications. Modification of the main modifiable factors such as quitting smoking, abstaining from alcohol, changing eating habits, and exercise seems to be the first step in preventing AF. The strict adherence to the treatment process of secondary causes predisposing to AF such as DM, hypertension, obesity, and sleep apnea is another step in the prevention of AF. Both an individual approach and global public health campaigns can be highly beneficial to reduce the risk of AF. In this review, we aimed to summarize the current evidence on the relationship between modifiable risk factors and AF, and the impact of possible interventions on these factors in preventing or reducing the AF burden in the light of recently published guidelines and studies.

Electronic Cigarette Nicotine Flux, Nicotine Yield, and Particulate Matter Emissions: Impact of Device and Liquid Heterogeneity

INTRODUCTION

Electronic cigarettes (ECIGs) heat a nicotine-containing liquid to produce an inhalable aerosol. ECIG power (wattage) and liquid nicotine concentration are two factors that predict nicotine emission rate ("flux"). These factors can vary greatly across devices and users.

AIMS AND METHODS

The purpose of this study was to examine ECIG device and liquid heterogeneity in "real world" settings and the association with predicted nicotine flux, nicotine yield, and total particulate matter (TPM) emissions. Past 30-day ECIG users (n = 84; mean age = 23.8 years [SD = 9.6]) reported device and liquid characteristics. Device power was measured via multimeter, device display screens, or obtained via labeling. Liquid nicotine concentration was obtained via labeling or through chemical analysis. Predicted nicotine flux, nicotine yield, and TPM associated with 10 4-second puffs were calculated for participants' primary devices.

RESULTS

Participants' primary devices were box mods (42.9%), disposable vapes (20.2%), and pod mods (36.9%). Most participants (65.5%) reported not knowing their primary device wattage. Rebuildable/box mods had the greatest power range (11.1-120.0 W); pod mod power also varied considerably (4.1-21.7 W). Unlike device wattage, most participants (95.2%) reported knowing their liquid nicotine concentration, which ranged from 3.0 to 86.9 mg/ml (M = 36.0, SD = 29.3). Predicted nicotine flux varied greatly across products (range =12.0-160.1 μg/s, M = 85.6 μg/s, SD = 34.3). Box mods had the greatest variability in wattage and predicted nicotine flux, nicotine yield, and TPM yield.

CONCLUSIONS

ECIG device and liquid heterogeneity influence nicotine and other toxicant emissions. Better measurement of ECIG device and liquid characteristics is needed to understand nicotine and toxicant emissions and to inform regulatory policy.

IMPLICATIONS

ECIG device and liquid heterogeneity cause great variability in nicotine flux and toxicants emitted. These data demonstrate the need to examine device and liquid characteristics to develop empirically informed, health-promoting regulatory policies. Policies may include setting product standards such that ECIG products cannot (1) have nicotine fluxes much greater than that of a cigarette to decrease the risk of dependence, (2) have nicotine fluxes that are very low and thus would have minimal appeal to cigarette smokers and may serve as starter products for youth or nontobacco users, and (3) emit large amounts of particulate matter and other toxicants.

Use of Swedish smokeless tobacco during pregnancy: A systematic review of pregnancy and early life health risk

BACKGROUND AND AIMS

Smokeless tobacco is a heterogeneous product group with diverse composition and prevalence globally. Tobacco use during pregnancy is concerning due to the risk of adverse pregnancy outcomes and effects on child health. Nicotine may mediate several of these effects. This systematic review measured health outcomes from Swedish smokeless tobacco (snus) use during pregnancy.

METHOD

Literature search was conducted by an information specialist in May 2022. We included human studies of snus use during pregnancy compared with no tobacco use, assessed risk of bias, conducted a meta-analysis and assessed confidence in effect-estimates using Grading of Recommendations, Assessment, Development and Evaluations (GRADE).

RESULTS

We included 18 cohort studies (42 to 1 006 398 participants). Snus use during pregnancy probably (moderate confidence in risk estimates) increase the risk of neonatal apnea, adjusted odds ratio 95% confidence interval [aOR (95% CI)] 1.96 (1.30 to 2.96). Snus use during pregnancy possibly (low confidence in risk estimates) increase the risk of stillbirths aOR 1.43 (1.02 to 1.99), extremely premature births aOR 1.69 (1.17 to 2.45), moderately premature birth aOR 1.26 (1.15 to 1.38), SGA aOR 1.26 (1.09 to 1.46), reduced birth weight mean difference of 72.47 g (110.58 g to 34.35 g reduction) and oral cleft malformations aOR 1.48 (1.00 to 2.21). It is uncertain (low confidence in risk estimates, CI crossing 1) whether snus use during pregnancy affects risk of preeclampsia aOR 1.11 (0.97 to 1.28), antenatal bleeding aOR 1.15 (0.92 to 1.44) and very premature birth aOR 1.26 (0.95 to 1.66). Risk of early neonatal mortality and altered heart rate variability is uncertain, very low confidence. Snus using mothers had increased prevalence of caesarean sections, low confidence.

CONCLUSIONS

This systematic review reveals that use of smokeless tobacco (snus) during pregnancy may adversely impact the developing child.

E-cigarette aerosol impairs male mouse skeletal muscle force development and prevents recovery from injury

To date, there has been a lag between the rise in E-cigarette use and an understanding of the long-term health effects. Inhalation of E-cigarette aerosol delivers high doses of nicotine, raises systemic cytokine levels, and compromises cardiopulmonary function. The consequences for muscle function have not been thoroughly investigated. The present study tests the hypothesis that exposure to nicotine-containing aerosol impairs locomotor muscle function, limits exercise tolerance, and interferes with muscle repair in male mice. Nicotine-containing aerosol reduced the maximal force produced by the extensor digitorum longus (EDL) by 30%-40% and, the speed achieved in treadmill running by 8%. Nicotine aerosol exposure also decreased adrenal and increased plasma epinephrine and norepinephrine levels, and these changes in catecholamines manifested as increased muscle and liver glycogen stores. In nicotine aerosol exposed mice, muscle regenerating from overuse injury only recovered force to 80% of noninjured levels. However, the structure of neuromuscular junctions (NMJs) was not affected by e-cigarette aerosols. Interestingly, the vehicle used to dissolve nicotine in these vaping devices, polyethylene glycol (PG) and vegetable glycerin (VG), decreased running speed by 11% and prevented full recovery from a lengthening contraction protocol (LCP) injury. In both types of aerosol exposures, cardiac left ventricular systolic function was preserved, but left ventricular myocardial relaxation was altered. These data suggest that E-cigarette use may have a negative impact on muscle force and regeneration due to compromised glucose metabolism and contractile function in male mice.NEW & NOTEWORTHY In male mice, nicotine-containing E-cigarette aerosol compromises muscle contractile function, regeneration from injury, and whole body running speeds. The vehicle used to deliver nicotine, propylene glycol, and vegetable glycerin, also reduces running speed and impairs the restoration of muscle function in injured muscle. However, the predominant effects of nicotine in this inhaled aerosol are evident in altered catecholamine levels, increased glycogen content, decreased running capacity, and impaired recovery of force following an overuse injury.

E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice

E-cigarette use has surged, but the long-term health effects remain unknown. E-cigarette aerosols containing nicotine and acrolein, a combustion and e-cigarette byproduct, may impair cardiac electrophysiology through autonomic imbalance. Here we show in mouse electrocardiograms that acute inhalation of e-cigarette aerosols disturbs cardiac conduction, in part through parasympathetic modulation. We demonstrate that, similar to acrolein or combustible cigarette smoke, aerosols from e-cigarette solvents (vegetable glycerin and propylene glycol) induce bradycardia, bradyarrhythmias, and elevations in heart rate variability during inhalation exposure, with inverse post-exposure effects. These effects are slighter with tobacco- or menthol-flavored aerosols containing nicotine, and in female mice. Yet, menthol-flavored and PG aerosols also increase ventricular arrhythmias and augment early ventricular repolarization (J amplitude), while menthol uniquely alters atrial and atrioventricular conduction. Exposure to e-cigarette aerosols from vegetable glycerin and its byproduct, acrolein, diminish heart rate and early repolarization. The pro-arrhythmic effects of solvent aerosols on ventricular repolarization and heart rate variability depend partly on parasympathetic modulation, whereas ventricular arrhythmias positively associate with early repolarization dependent on the presence of nicotine. Our study indicates that chemical constituents of e-cigarettes could contribute to cardiac risk by provoking pro-arrhythmic changes and stimulating autonomic reflexes.

Embolic Stroke Following Ingestion of Liquid Nicotine Refill Solution

The use of e-cigarettes is gaining popularity despite knowing about cardiovascular health risks. Cases of intentional or accidental intoxication following ingestion of the refill solution are also a growing concern. Most of these cases were fatal and related to cardiac arrest and hypoxic brain injury. We report the case of a 54-year-old woman who developed bilateral acute ischemic stroke in the anterior and posterior cerebral circulation following intentional oral intake of e-liquid nicotine refill solution. The diagnostic work-up concluded an etiology of embolic stroke of undetermined source, most likely of cardiac origin. We assume that sympathetic overactivation lead to temporary cardiac arrhythmia and subsequent thrombi formation. Moreover, we discuss several additional pathogenic aspects of oral intake of e-liquid refill solution for the development of central nervous system pathology. This case expands the clinical spectrum of health hazards associated with the introduction of e-cigarettes and raises awareness of the need for preventive measures.

Risk and safety profile of electronic nicotine delivery systems (ENDS): an umbrella review to inform ENDS health communication strategies

OBJECTIVES

This umbrella review aims to summarise the evidence about electronic nicotine delivery systems' (ENDS) risk and safety health profile to inform ENDS health communication strategies.

DATA SOURCES AND STUDY SELECTION

Six databases were searched for systematic reviews presenting evidence on ENDS-related health effects. Ninety reviews divided into five categories were included: toxicity=20, health effects=40, role in smoking cessation=24, role in transition to combustible cigarettes (CCs)=13 and industry marketing claims=4.

DATA EXTRACTION

Findings were synthesised in narrative summaries. Meta-analyses were conducted by study type when appropriate. Quality assessment was conducted using the Measurement Tool to Assess Systematic Reviews. The Institute of Medicine's Levels of Evidence Framework was used to classify the evidence into high-level, moderate, limited-suggestive and limited-not-conclusive.

DATA SYNTHESIS

We found high-level evidence that ENDS exposes users to toxic substances; increases the risk of respiratory disease; leads to nicotine dependence; causes serious injuries due to explosion or poisoning; increases smoking cessation in clinical trials but not in observational studies; increases CC initiation; and exposure to ENDS marketing increases its use/intention to use. Evidence was moderate for ENDS association with mental health and substance use, limited-suggestive for cardiovascular, and limited-not-conclusive for cancer, ear, ocular and oral diseases, and pregnancy outcomes.

CONCLUSIONS

As evidence is accumulating, ENDS communication can focus on high-level evidence on ENDS association with toxicity, nicotine addiction, respiratory disease, ENDS-specific harm (explosion, poisoning) and anti-ENDS industry sentiment. Direct comparison between the harm of CCs and ENDS should be avoided.

PROSPERO REGISTRATION NUMBER

CRD42021241630.

Electronic Cigarette and Atherosclerosis: A Comprehensive Literature Review of Latest Evidences

Coronary artery diseases (CAD), also known as coronary heart disease (CHD), are the world’s leading cause of death. The basis of coronary artery disease is the narrowing of the heart coronary artery lumen due to atherosclerosis. The use of electronic cigarettes has increased significantly over the years. However, harmful effects of electronic cigarettes are still not firm. The aim of this article is to review the impact of electronic cigarette and its role in the pathogenesis of atherosclerosis from recent studies. The results showed that several chemical compounds, such as nicotine, propylene glycol, particulate matters, heavy metals, and flavorings, in electronic cigarette induce atherosclerosis with each molecular mechanism that lead to atherosclerosis progression by formation of ROS, endothelial dysfunction, and inflammation. Further research is still needed to determine the exact mechanism and provide more clinical evidence.

Cardiopulmonary Consequences of Vaping in Adolescents: A Scientific Statement From the American Heart Association

Although the US Food and Drug Administration has not approved e-cigarettes as a cessation aid, industry has at times positioned their products in that way for adults trying to quit traditional cigarettes; however, their novelty and customizability have driven them into the hands of unintended users, particularly adolescents. Most new users of e-cigarette products have never smoked traditional cigarettes; therefore, understanding the respiratory and cardiovascular consequences of e-cigarette use has become of increasing interest to the research community. Most studies have been performed on adult e-cigarette users, but the majority of these study participants are either former traditional smokers or smokers who have used e-cigarettes to switch from traditional smoking. Therefore, the respiratory and cardiovascular consequences in this population are not attributable to e-cigarette use alone. Preclinical studies have been used to study the effects of naive e-cigarette use on various organ systems; however, almost all of these studies have used adult animals, which makes translation of health effects to adolescents problematic. Given that inhalation of any foreign substance can have effects on the respiratory and cardiovascular systems, a more holistic understanding of the pathways involved in toxicity could help to guide researchers to novel therapeutic treatment strategies. The goals of this scientific statement are to provide salient background information on the cardiopulmonary consequences of e-cigarette use (vaping) in adolescents, to guide therapeutic and preventive strategies and future research directions, and to inform public policymakers on the risks, both short and long term, of vaping.

Secondary Prevention after Myocardial Infarction: What to Do and Where to Do It

Acute myocardial infarction is a manifestation of atherosclerosis which may be fatal. In-hospital and short-term mortality rates after an acute myocardial infarction have declined in the past few decades. However, although long-term mortality has decreased, it remains unacceptably high. This review paper summarises the non-pharmacological interventions (smoking cessation, physical activity, nutrition, and psychosocial intervention) and pharmacological approaches (antiplatelet and lipid-lowering therapy, renin-angiotensin-aldosterone system inhibitors, beta-blockers, and glucose-lowering drugs) to secondary prevention after a myocardial infarction. The provision of secondary prevention services is established through cardiac rehabilitation, which consists of several discussed components. Finally, we discuss the quality indicators for long-term care after an acute myocardial infarction.

Flavored and Nicotine-Containing E-Cigarettes Induce Impaired Angiogenesis and Diabetic Wound Healing via Increased Endothelial Oxidative Stress and Reduced NO Bioavailability

The prevalent use of electronic cigarettes (e-cigarettes) has increased exponentially in recent years, especially in youth who are attracted to flavored e-cigarettes. Indeed, e-cigarette or vaping product use-associated lung injury (EVALI) cases started to emerge in the United States in August 2019, resulting in 2807 hospitalized cases and 68 deaths as of 18 February 2020. In the present study, we investigated, for the first time, whether flavored and nicotine containing e-cigarettes induce endothelial dysfunction to result in impaired angiogenesis and wound healing particularly under diabetic condition. Nicotine containing e-cigarettes with various contents of nicotine (0, 1.2%, 2.4%), and flavored e-cigarettes of classic tobacco, mint, menthol, and vanilla or fruit from BLU (nicotine 2.4%) or JUUL (nicotine 3%), were used to treat endothelial cells in vitro and streptozotocin-induced diabetic mice in vivo. Endothelial cell superoxide production, determined by dihydroethidium (DHE) fluorescent imaging and electron spin resonance (ESR), was markedly increased by exposure to e-cigarette extract (e-CSE) in a nicotine-content dependent manner, while nitric oxide (NO) bioavailability detected by DAF-FM fluorescent imaging was substantially decreased. All of the different flavored e-cigarettes examined also showed significant effects in increasing superoxide production while diminishing NO bioavailability. Endothelial cell apoptosis evaluated by caspase 3 activity was markedly increased by exposure to e-CSE prepared from flavored and nicotine containing e-cigarettes. Endothelial monolayer wound assays revealed that nicotine-containing and flavored e-cigarettes induced impaired angiogenic wound repair of endothelial cell monolayers. Furthermore, vascular endothelial growth factor (VEGF) stimulated wound healing in diabetic mice was impaired by exposure to e-CSEs prepared from nicotine-containing and flavored e-cigarettes. Taken together, our data demonstrate for the first time that flavored and nicotine-containing e-cigarettes induce endothelial dysfunction through excessive ROS production, resulting in decreased NO bioavailability, increased endothelial cell apoptosis, and impairment in angiogenesis and wound healing, especially under diabetic condition. These responses of endothelial dysfunction likely underlie harmful effects of e-cigarettes in endothelial-rich organs, such as heart and lungs. These data also indicate that rigorous regulation on e-cigarette use should be enforced in diabetic and/or surgical patients to avoid severe consequences from impaired angiogenesis/wound healing.

Cardiovascular Outcomes among Combustible-Tobacco and Electronic Nicotine Delivery System (ENDS) Users in Waves 1 through 5 of the Population Assessment of Tobacco and Health (PATH) Study, 2013-2019

BACKGROUND

Prior studies have not clearly established risk of cardiovascular disease (CVD) among smokers who switch to exclusive use of electronic nicotine delivery systems (ENDS). We compared cardiovascular disease incidence in combustible-tobacco users, those who transitioned to ENDS use, and those who quit tobacco with never tobacco users.

METHODS

This prospective cohort study analyzes five waves of Population Assessment of Tobacco and Health (PATH) Study data, Wave 1 (2013-2014) through Wave 5 (2018-2019). Cardiovascular disease (CVD) incidence was captured over three intervals (Waves 1 to 3, Waves 2 to 4, and Waves 3 to 5). Participants were adults (40+ years old) without a history of CVD for the first two waves of any interval. Change in tobacco use status, from exclusive past 30 day use of any combustible-tobacco product to either exclusive past 30 day ENDS use, dual past 30 day use of ENDS and combustible-tobacco, or no past 30 day use of any tobacco, between the first two waves of an interval was used to predict onset of CVD between the second and third waves in the interval. CVD incidence was defined as a new self-report of being told by a health professional that they had congestive heart failure, stroke, or a myocardial infarction. Generalized estimating equation (GEE) analyses combined 10,548 observations across intervals from 7820 eligible respondents.

RESULTS

Overall, there were 191 observations of CVD among 10,548 total observations (1.7%, standard error (SE) = 0.2), with 40 among 3014 never users of tobacco (1.5%, SE = 0.3). In multivariable models, CVD incidence was not significantly different for any tobacco user groups compared to never users. There were 126 observations of CVD among 6263 continuing exclusive combustible-tobacco users (adjusted odds ratio [AOR] = 1.44; 95% confidence interval (CI) 0.87-2.39), 15 observations of CVD among 565 who transitioned to dual use (AOR = 1.85; 0.78-4.37), and 10 observations of CVD among 654 who quit using tobacco (AOR = 1.18; 0.33-4.26). There were no observations of CVD among 53 who transitioned to exclusive ENDS use.

CONCLUSIONS

This study found no difference in CVD incidence by tobacco status over three 3 year intervals, even for tobacco quitters. It is possible that additional waves of PATH Study data, combined with information from other large longitudinal cohorts with careful tracking of ENDS use patterns may help to further clarify this relationship.

Acute Effects of Electronic and Tobacco Cigarette Smoking on Sympathetic Nerve Activity and Blood Pressure in Humans

Acute tobacco cigarette (TC) smoking increases blood pressure and sympathetic nerve activity, whereas there are scarce data on the impact of electronic cigarette (EC) smoking. We assessed the acute effects of TC, EC and sham smoking on blood pressure, heart rate and sympathetic nervous system. Methods: We studied 12 normotensive male habitual smokers (mean age 33 years) free of cardiovascular disease. The study design was randomized and sham controlled with three experimental sessions (sham smoking, TC smoking and EC smoking). After baseline measurements at rest, the subjects were then asked to smoke (puffing habits left uncontrolled) two TC cigarettes containing 1.1 mg nicotine, EC smoking or simulated smoking with a drinking straw with a filter (sham smoking), in line with previous methodology. Results: EC smoking at 5 and 30 min compared to baseline was accompanied by the augmentation of mean arterial pressure (MAP) and heart rate (p < 0.001 for all). The muscle sympathetic nerve activity (MSNA) decrease was significant during both TC and EC sessions (p < 0.001 for both comparisons) and was similar between them (−25.1% ± 9.8% vs. −34.4% ± 8.3%, respectively, p = 0.018). Both MSNA decreases were significantly higher (p < 0.001 for both comparisons) than that elicited by sham smoking (−4.4% ± 4.8%). Skin sympathetic nerve activity increase was significant in both TC and EC groups (p < 0.001 for both comparisons) and similar between them (73.4% ± 17.9% and 71.9% ± 7%, respectively, p = 0.829). Conclusions: The unfavorable responses of sympathetic and arterial pressure to EC smoking are similar to those elicited by TC in healthy habitual smokers.

Electronic Cigarette Exposure Causes Vascular Endothelial Dysfunction Due to NADPH Oxidase Activation and eNOS Uncoupling

We recently reported a mouse model of chronic electronic cigarette (e-cig) exposure-induced cardiovascular pathology, where long-term exposure to e-cig vape (ECV) induces cardiac abnormalities, impairment of endothelial function, and systemic hypertension. Here, we delineate the underlying mechanisms of ECV-induced vascular endothelial dysfunction (VED), a central trigger of cardiovascular disease. C57/BL6 male mice were exposed to ECV generated from e-cig liquid containing 0, 6, or 24 mg/ml nicotine for 16 and 60 weeks. Time-dependent elevation in blood pressure and systemic vascular resistance were observed, along with an impairment of acetylcholine-induced aortic relaxation in ECV-exposed mice, compared to air-exposed control. Decreased intravascular nitric oxide (NO) levels and increased superoxide generation with elevated 3-nitrotyrosine levels in the aorta of ECV-exposed mice were observed, indicating that ECV-induced superoxide reacts with NO to generate cytotoxic peroxynitrite. Exposure increased NADPH oxidase expression, supporting its role in ECV-induced superoxide generation. Downregulation of endothelial nitric oxide synthase (eNOS) expression and Akt-dependent eNOS phosphorylation occurred in the aorta of ECV-exposed mice, indicating that exposure inhibited de novo NO synthesis. Following ECV exposure, the critical NOS cofactor tetrahydrobiopterin was decreased, with a concomitant loss of its salvage enzyme, dihydrofolate reductase. NADPH oxidase and NOS inhibitors abrogated ECV-induced superoxide generation in the aorta of ECV exposed mice. Together, our data demonstrate that ECV exposure activates NADPH oxidase and uncouples eNOS, causing a vicious cycle of superoxide generation and vascular oxidant stress that triggers VED and hypertension with predisposition to other cardiovascular disease.

E-Cigarettes and Cardiopulmonary Health: Review for Clinicians

Electronic cigarettes (e-cigarettes) are battery powered electronic nicotine delivery systems that use a propylene glycol/vegetable glycerin base to deliver vaporized nicotine and flavorings to the body. E-cigarettes became commercially available without evidence regarding their risks, long-term safety, or utility in smoking cessation. Recent clinical trials suggest that e-cigarette use with counseling may be effective in reducing cigarette use but not nicotine dependence. However, meta-analyses of observational studies demonstrate that e-cigarette use is not associated with smoking cessation. Cardiovascular studies reported sympathetic activation, vascular stiffening, and endothelial dysfunction, which are associated with adverse cardiovascular events. The majority of pulmonary clinical trials in e-cigarette users included standard spirometry as the primary outcome measure, reporting no change in lung function. However, studies reported increased biomarkers of pulmonary disease in e-cigarette users. These studies were conducted in adults, but >30% of high school-age adolescents reported e-cigarette use. The effects of e-cigarette use on cardiopulmonary endpoints in adolescents and young adults remain unstudied. Because of adverse clinical findings and associations between e-cigarette use and increased incidence of respiratory diseases in people who have never smoked, large longitudinal studies are needed to understand the risk profile of e-cigarettes. Consistent with the Centers for Disease Control and Prevention recommendations, clinicians should monitor the health risks of e-cigarette use, discourage nonsmokers and adolescents from using e-cigarettes, and discourage smokers from engaging in dual use without cigarette reduction or cessation.

E-Cigarette Toxicology

Since the spread of tobacco from the Americas hundreds of years ago, tobacco cigarettes and, more recently, alternative tobacco products have become global products of nicotine addiction. Within the evolving alternative tobacco product space, electronic cigarette (e-cigarette) vaping has surpassed conventional cigarette smoking among adolescents and young adults in the United States and beyond. This review describes the experimental and clinical evidence of e-cigarette toxicity and deleterious health effects. Adverse health effects related to e-cigarette aerosols are influenced by several factors, including e-liquid components, physical device factors, chemical changes related to heating, and health of the e-cigarette user (e.g., asthmatic). Federal, state, and local regulations have attempted to govern e-cigarette flavors, manufacturing, distribution, and availability, particularly to underaged youths. However, the evolving e-cigarette landscape continues to impede timely toxicological studies and hinder progress made toward our understanding of the long-term health consequence of e-cigarettes.

Comparison of Oxidative Effects of Electronic Cigarette and Tobacco Smoke Exposure Performed Experimentally

OBJECTIVE

Cigarette smoking is a life-threatening habit that has rapidly spread in every socioeconomic part of the public worldwide. There exist mechanisms of nicotine delivery available to use in the hope of halting cigarette smoking, and the electronic cigarette (EC) is one of the common methods used for tobacco smoking replacement. This study aimed to investigate experimentally the oxidative effects of tobacco smoke and EC smoke which contain nicotine.

METHOD

We constructed smoke circuit rooms for exposing the rats to EC or tobacco smoke. Three groups were created, the control group (N = 8); the electronic cigarette group (N = 8), exposure to electronic cigarette smoke for 2 h per day; and the tobacco group (N = 8), exposure to traditional cigarette smoke for 2 h per day. After the first and second week of exposure, blood samples were obtained, and serum oxidative stress index (OSI), paraoxonase 1 (PON1) activity, and prolidase levels were evaluated.

RESULTS

Higher values of OSI and prolidase levels were detected in the first week of EC or tobacco smoke exposure in both study groups (p < 0.001) when compared with the control group, and partial decrements were observed in the second week. By contrast, elevated PON1 levels were observed in the second week after EC or tobacco smoke exposure. The highest OSI levels were observed in the tobacco smoke group (p < 0.001). The lowest values of PON1 levels were detected in the first week of the electronic cigarette smoke group, and this decremental value was statistically different than normal, the second week of the electronic cigarette smoke group, the first week of the traditional cigarette smoke exposure group, and the second week of the traditional cigarette smoke exposure group values (p < 0.000).

CONCLUSION

Our results indicate that EC smoke induced oxidative stress. Therefore, ECs are potentially risky for human health and can lead to important health problems.

Electronic cigarettes and health with special focus on cardiovascular effects: position paper of the European Association of Preventive Cardiology (EAPC)

BACKGROUND

Tobacco use is the single largest preventable risk factor for premature death of non-communicable diseases and the second leading cause of cardiovascular disease. In response to the harmful effects of tobacco smoking, the use of electronic cigarettes (e-cigarettes) has emerged and gained significant popularity over the past 15 years. E-cigarettes are promoted as safe alternatives for traditional tobacco smoking and are often suggested as a way to reduce or quit smoking. However, evidence suggests they are not harmless.

DISCUSSION

The rapid evolution of the e-cigarette market has outpaced the legislator's regulatory capacity, leading to mixed regulations. The increasing use of e-cigarettes in adolescents and young individuals is of concern. While the long-term direct cardiovascular effects of e-cigarettes remain largely unknown, the existing evidence suggests that the e-cigarette should not be regarded as a cardiovascular safe product. The contribution of e-cigarette use to reducing conventional cigarette use and smoking cessation is complex, and the impact of e-cigarette use on long-term cessation lacks sufficient evidence.

CONCLUSION

This position paper describes the evidence regarding the prevalence of e-cigarette smoking, uptake of e-cigarettes in the young, related legislations, cardiovascular effects of e-cigarettes and the impact of e-cigarettes on smoking cessation. Knowledge gaps in the field are also highlighted. The recommendations from the population science and public health section of the European Association of Preventive Cardiology are presented.

Immediate physiological effects of acute electronic cigarette use in humans: A systematic review and meta-analysis

BACKGROUND

Electronic cigarettes (e-cigs) are widely used devices that were initially created to aid in smoking cessation. However, their acute physiological effects are unclear and there have been a number of E-cig and Vaping Acute Lung Injury (EVALI) events reported.

RESEARCH QUESTION

What are the immediate physiological effects (i.e. cardiovascular, respiratory or blood-based responses) of acute e-cig usage in humans?

STUDY DESIGN AND METHODS

PubMed, Web of Science, Cochrane and Scopus databases were searched for English or French peer-reviewed articles published until May 20, 2021 and measuring at least one physiological parameter before and after using an e-cig. The study followed PRISMA guidelines and assessed article quality using the Downs and Black checklist. Independent extraction was conducted by two reviewers. Data were pooled using random-effect models. Sensitivity analysis and meta-regressions were performed to explore heterogeneity.

MAIN OUTCOMES

Systolic and diastolic blood pressure, heart rate, augmentation index (AIx75), fraction of exhaled nitric oxide (FeNO), and spirometry were the most frequently assessed parameters and were therefore chosen for meta-analyses.

RESULTS

Of 19823 articles screened, 45 articles were included for the qualitative synthesis, and 27 articles (919 patients) were included in meta-analyses. Acute use of nicotine e-cig was associated with increased heart rate(SMD = 0.71; 95%CI 0.46-0.95), systolic blood pressure (SMD = 0.38; 95%CI 0.18-0.57), diastolic blood pressure (SMD = 0.52; 95%CI 0.33-0.70), and augmentation index AIx75 (SMD = 0.580; 95%CI 0.220-0.941), along with decreased FeNO (SMD = -0.26; 95%CI -0.49 to -0.04). E-cig exposure wasn't associated with significant changes in any spirometry measure.

INTERPRETATION

Acute use of nicotine e-cigs was associated with statistically significant cardiovascular and respiratory responses. These devices have a physiological impact that could be clinically relevant, especially in terms of cardiovascular morbidity. However, the direct consequences of long-term e-cig use needs to be further explored.

Short-Term Cardiovascular Effects of E-Cigarettes in Adults Making a Stop-Smoking Attempt: A Randomized Controlled Trial

Simple Summary

E-cigarettes are popular for smoking cessation but knowledge of their effect on cardiovascular health is limited. We compared the short-term cardiovascular effects in 248 smokers who quit smoking using e-cigarettes with or without nicotine or prescription nicotine replacement therapy (NRT). All participants received behavioural support. We assessed the cardiovascular effects of these stop smoking methods 3 days following quit date. Our work suggests that e-cigarettes offer similar vascular health benefits to that of NRT. This happens at a very early stage in the stop smoking process (3 days).

Abstract

Smoking increases cardiovascular disease (CVD) risk by leading to endothelial injury. E-cigarettes remain a popular way to stop smoking. Evidence on their effect on cardiovascular health is growing but remains limited, particularly in the short-term. The main objective of this study was to compare short-term cardiovascular effects in smokers who quit smoking using e-cigarettes with or without nicotine or prescription nicotine replacement therapy (NRT). This was a single-centre (Sheffield, UK) pragmatic three-arm randomised controlled trial which recruited adult smokers (≥10 cigarettes per day), who were willing to attempt to stop smoking with support (n = 248). Participants were randomised to receive either: (a) behavioral support and e-cigarettes with 18 mg/mL nicotine (n = 84); (b) behavioral support and e-cigarettes without nicotine (n = 82); (c) behavioral support and NRT (n = 82). Flow Mediated Dilation (%FMD), peak cutaneous vascular conductance responses to acetylcholine (ACh) and sodium nitroprusside (SNP) and mean arterial pressure (MAP) were recorded at baseline and three days after stopping smoking. General Linear Models were used to compare changes between groups and changes from follow-up. Adjusting for baseline, at follow-up, all outcomes (for the 208 participants that completed the 3-day assessments) with the exception of SNP had improved significantly over baseline and there were no differences between groups (%FMD F = 1.03, p = 0.360, df = 2,207; ACh F = 0.172, p = 0.84, df = 2,207; SNP F = 0.382, p = 0.68, df = 2,207; MAP F = 0.176, p = 0.84, df = 2,207). For smokers ≥20 cigarettes per day, benefits were also pronounced. Smoking cessation showed positive cardiovascular impact even after a 3-day period and the effects did not differ between nicotine-containing e-cigarettes, nicotine-free e-cigarettes and NRT.

E-cigarette Smoking (Vaping) and Markers of Vascular Wall Damage in Young Subjects without Cardiovascular Disease

Aim: to investigate the effect of nicotine-containing vapes in comparison with traditional tobacco smoking on markers of vascular wall damage: high sensitivity C-reactive protein (hsCRP), albuminuria (AU), and ankle-brachial index (ABI).

Material and Methods: We examined 369 young subjects without cardiovascular diseases (age median 21 [20;21] years) (159 men and 210 women). The hsCRP levels in the serum were assessed by immunochromatographic express method. AU was investigated in daily urine by a quantitative reflex photometry. ABI was determined by plethysmography.

Results: All subjects were divided into groups: non-smokers (n=196, 53.1%), smokers of traditional cigarettes (n=83, 22.5%) and smokers of nicotine-containing vapes (n=90, 24.4%). The groups did not differ in main anthropometric data. Median hsCRP levels in smokers (14.30 [11; 16.5] mg/l in tobacco-smokers and 13.15 [9.65; 17.5] mg/l in vapers) were significantly higher vs nonsmokers (3.0 [2; 5.6] mg/l). In tobacco-smokers (33.0  [21.5;  60]  mg)  and  vape  smokers  (45.0  [20;  115]  mg),  the  median  AU  was  statistically  significantly  higher  than  in  non-smokers  (12.0 [10; 20] mg). ABI levels were significantly lower in the groups of tobacco smokers (0.98 [0.91; 0.99]) and vapers (0.85 [0.79; 0.93]) when compared with nonsmokers (1.125 [1.01; 1.18]), and the median ABI in vapers was lower than in tobacco smokers (p<0.001). In the group of tobacco smokers, the hsCRP level correlated with the smoker's index (rs=0.31, p<0.05), and AU (rs=0.54, p<0.05) and ABI (rs=-0.28, p<0.05) with a daily inhaled nicotine dose. In the group of vapers, CRP was associated with smoking experience (rs=0.338, p<0.05), AU with a daily inhaled nicotine dose (rs=0.79,  p<0.05), and  ABI with  BMI (rs=-0.33,  p<0.05), heart  rate (rs=-0.24,  p<0.05) and  smoking experience  (rs=-0.235, p<0.05). According to the results of multivariate regression analysis the hsCRP level was related with only the smoking experience (B=0.91±0.19, p=0.000005), AU level with the daily inhaled nicotine dose (B=1.59±0.7, p=0.0121) and smoking experience (B=3.07±1.23, p=0.0179), and ABI level with only smoking experience (B=-0.09±0.004, p=0.0419).

Conclusion: In smokers, both traditional and vapers, the levels of hsCRP, AU are significantly higher, and the ABI is lower than in healthy young nonsmokers. The most significant influence on the level of hsCRP is exerted by the experience of  tobacco  and  vape  smoking;  to  the  AU  level  – the experience of tobacco and vaping and the daily inhaled nicotine dose, and by the value of the ABI – the experience of vaping.

Effects of physical exercise on baroreflex sensitivity and renal sympathetic nerve activity in chronic nicotine-treated rats

Chronic nicotine exposure may increase cardiovascular risk by impairing the cardiac autonomic function. Besides, physical exercise (PE) has shown to improve cardiovascular health. Thus, we aimed to investigate the effects of PE on baroreflex sensitivity (BRS), heart rate variability (HRV), and sympathetic nerve activity (SNA) in chronically nicotine-exposed rats. Male Wistar rats were assigned to four independent groups: Control (treated with saline solution), Control+Ex (treated with saline and submitted to treadmill training), Nicotine (treated with Nicotine), and Nicotine+Ex (treated with nicotine and submitted to treadmill training). Nicotine (1 mg·kg-1) was administered daily for 28 consecutive days. PE consisted of running exercise (60%-70% of maximal aerobic capacity) for 45 min, 5 days per week, for 4 weeks. At the end of the protocol, cardiac BRS, HRV, renal SNA (rSNA), and renal BRS were assessed. Nicotine treatment decreased absolute values of HRV indexes, increased low frequency/high frequency ratio of HRV, reduced the bradycardic and sympatho-inhibitory baroreceptor reflex responses, and reduced the rSNA. PE effectively restored time-domain HRV indexes, the bradycardic and sympatho-inhibitory reflex responses, and the rSNA in chronic nicotine-treated rats. PE was effective in preventing the deterioration of time-domain parameters of HRV, arterial baroreceptor dysfunction, and the rSNA after nicotine treatment.

Toxicity of electronic cigarettes: A general review of the origins, health hazards, and toxicity mechanisms

Electronic cigarettes (E-cigarette) are an alternative for traditional cigarette smokers to quit smoking. Based on the current understanding, electronic cigarettes have rapidly become popular among existing smokers and former non-smokers. However, increasing research at different levels reveals that e-cigarettes are unsafe. This review provides an overview of the toxicology of e-cigarettes based on existing in vivo and in vitro studies and compares their toxicity with that of traditional cigarettes. Moreover, we describe the associated toxicity components in e-cigarettes, as well as the potential mechanism by which e-cigarettes exert toxic effects. As is known to all, the nicotine in traditional cigarettes and e-cigarettes has certain toxicity. Besides, a few studies have shown that propylene glycol and vegetable glycerin mixture and flavoring agents in e-cigarettes also are the key components causing adverse effects in animals or cells. There is insufficient scientific evidence on the toxicity of e-cigarettes due to the lack of standardized research methods, prompting the need to conduct a comprehensive toxicity assessment of e-cigarette toxicity to elucidate the safety issues of e-cigarettes. Eventually, a basis for decision-making on whether people use e-cigarettes will be obtained.

Risk Factors and Medical Symptoms Associated With Electronic Vapor Product Use Among Adolescents and Young Adults

The use of electronic vapor products (EVPs) has increased dramatically in the past decade. The objectives of our study were to examine the frequency of EVP use; to identify demographic characteristics, risk-taking behaviors, and beliefs about vaping; and to determine symptoms associated with EVPs among adolescents. A questionnaire addressing these objectives was administered to a convenience sample of subjects aged 12 to 23 years. Among 494 completed questionnaires, 80% of responders were considered experimenters/nonusers (never tried or tried one time) and 20% were considered frequent users (at least once a month). We identified demographic features and risk-taking behaviors associated with EVP use. In the previous 6 months, frequent users were more likely to report headache, cough, sleep disturbances, dehydration, weakness, racing heart, chest pain, and tremors. Our findings provide evidence to support efforts to decrease EVP use through screening, education, and preventative strategies.

Evaluation of the relationship between the level of addiction and exhaled carbon monoxide levels with QT dispersion in smokers

INTRODUCTION

Smoking increases the risk of arrhythmia. QT dispersion (QTd) is an important indicator for the determination of ventricular arrhythmia. In this study, we aimed to determine the arrhythmia risk by evaluating QTd in smokers and to assess the relationship between the level of nicotine addiction and carbon monoxide (CO) level in the expiratory air.

METHODS

This study was designed as a single-center, cross-sectional study. Among the chronic smokers referred to the Smoking Cessation Clinic of a tertiary hospital between October 2019 and January 2020, all those who had no risk factors for cardiac arrhythmias, except smoking, were included in the study. Sociodemographic data and smoking characteristics of the participants were collected and exhaled CO levels were measured. QT intervals were measured in all leads by using a 12-lead standard electrocardiogram (ECG), and heart rate corrected QT (QTc) intervals, QT dispersion (QTd), and corrected QT dispersion (QTcd) were calculated.

RESULTS

The mean age of the 250 patients was 37.2±9.3 years and the majority of patients (65%) were male. The mean amount of smoking was 25.74±16.03 packs/year and the mean value of CO was 12.36±7.06 ppm. The mean QTd was 23.83±13.12 ms, and the mean QTcd was 26.63±15.02 ms. A statistically significant relationship was found between QTd and QTcd and level of addiction, consumption of sticks/day and packs/year, and exhaled CO values (all p<0.001).

CONCLUSIONS

It was found that as the level of addiction, cigarette use amount, exhaled CO levels, and BMI increased in smokers, QT dispersion and arrhythmia risk increased.

Cardiorespiratory and Immunologic Effects of Electronic Cigarettes

PURPOSE OF REVIEW

Although e-cigarettes have become popular, especially among youth, the health effects associated with e-cigarette use remain unclear. This review discusses current evidence relating to the cardiovascular, pulmonary, and immunological effects of e-cigarettes.

RECENT FINDINGS

The use of e-cigarettes by healthy adults has been shown to increase blood pressure, heart rate, and arterial stiffness, as well as resistance to air flow in lungs. Inhalation of e-cigarette aerosol has been shown to elicit immune responses and increase the production of immunomodulatory cytokines in young tobacco-naïve individuals. In animal models, long-term exposure to e-cigarettes leads to marked changes in lung architecture, dysregulation of immune genes, and low-grade inflammation. Exposure to e-cigarette aerosols in mice has been shown to induce DNA damage, inhibit DNA repair, and promote carcinogenesis. Chronic exposure to e-cigarettes has also been reported to result in the accumulation of lipid-laden macrophages in the lung and dysregulation of lipid metabolism and transport in mice. Although, the genotoxic and inflammatory effects of e-cigarettes are milder than those of combustible cigarettes, some of the cardiorespiratory effects of the two insults are comparable. The toxicity of e-cigarettes has been variably linked to nicotine, as well as other e-cigarette constituents, operating conditions, and use patterns.

SUMMARY

The use of e-cigarettes in humans is associated with significant adverse cardiorespiratory and immunological changes. Data from animal models and in vitro studies support the notion that long-term use of e-cigarettes may pose significant health risks.