Cardiovascular autonomic effects of electronic cigarette use: a systematic review

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.

Impact of Electronic Cigarette use on Cardiovascular Health: Current Evidence, Causal Pathways, and Public Health Implications

Electronic cigarette (e-cigarette) use is increasing in Europe and the USA. While mounting evidence exists regarding an array of associated adverse health effects, to date limited evidence exists regarding the health effects of e-cigarette use on cardiovascular (CV) disease (CVD). The present review summarizes the effects of e-cigarette use on CV health. A search strategy of in vivo experimental, observational studies (including population-based cohort studies), and interventional studies was conducted in PubMed, MEDLINE, and Web of Science (April 1, 2009-April 1, 2022). The main findings revealed that the influence of e-cigarette on health are attributed mainly to the individual and interactive effects of flavors and additives used in e-cigarette fluids, along with the extended heating. The above collectively stimulate prolonged sympathoexcitatory CV autonomic effects, such as increased heart rate and diastolic blood pressure (BP), as well as decreased oxygen saturation. Hence, e-cigarette users are at increased risk of developing atherosclerosis, hypertension, arrhythmia, myocardial infarction, and heart failure. Such risks are anticipated to increase, especially among the young who are increasingly adopting e-cigarette use particularly with flavored additives. Further investigations are urgently needed to evaluate the long-term effects of e-cigarette use, particularly among susceptible population groups such as youth.

Assessing acute nicotine impact on choroidal thickness: a randomized, double-blinded study comparing smoking cessation aids, including nicotine gum and electronic cigarettes

PURPOSE

To explore whether differences in choroidal thickness arise from nicotine consumption in healthy young individuals, specifically comparing the effects of nicotine gum to electronic cigarette (vaping), while maintaining a consistent 4 mg nicotine dosage.

METHODS

In a randomized double-blinded prospective cross-sectional study, 20 healthy participants (mean age ± standard deviation: 23 ± 2.36 years) were randomly assigned to either the nicotine gum or vaping group. Choroidal thickness (ChT) measurements were conducted using optical coherence tomography (OCT) (Topcon 3D OCT-1 Maestro System) at baseline, 30, and 60 min after ingesting 4 mg of nicotine, with ChT measurements taken from five different horizontal areas.

RESULTS

Neither the nicotine delivery method (gum or vaping) demonstrated a statistically significant impact on ChT mean scores among subjects in the five measured areas at baseline, 30, and 60 min (p > 0.05). However, significant differences were observed in ChT mean scores within subjects across the five areas (F (1.83, 72) = 36.43, p < 0.001), regardless of other study factors such as group, time, and visit (p > 0.05). A statistically significant interaction was identified between the factors of area and time concerning participants' ChT mean scores when stratified by the type of smoking (tobacco, vaping, and dual) (p = 0.003).

CONCLUSION

The results of this study revealed that nicotine, up to particular concentration of 4 mg, does not have a statistically significant vasoconstrictive effect on choroidal thickness, regardless of the delivery method, within the examined group. These findings offer valuable insights into the relationship between nicotine intake and choroidal dynamics in young adults.

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.

Longitudinal associations between anxiety sensitivity and substance use in adolescents: Mediation by depressive affect

Though anxiety sensitivity (AS)-fear of anxiety-related experiences-is primarily tied to anxiety vulnerability, AS has also been prospectively associated with general negative affect and depression. Furthermore, depression has been longitudinally associated with different forms of substance use, and some AS subfactors (e.g., cognitive concerns) have been associated more consistently with depression and substance use than others. However, no previous study has investigated if longitudinal associations of AS with substance use may be mediated by depression or whether aspects of AS may be prospectively associated with substance use among adolescents. Hence, the present study tested depressive affect (the negative affective aspect of depression) as a prospective mediator of AS associations with substance use and examined longitudinal AS subfactor associations with substance use and problems. High school 9th graders (N = 2,877; Mage = 14.1 years; 55.3% female) completed self-report measures at baseline and at 6 months and 1 year later. Depressive affect mediated AS associations with subsequent alcohol, cigarette, electronic cigarette, cannabis, benzodiazepine, and opioid use. Also, AS cognitive and social concerns (vs. physical concerns) were more consistently associated with later depressive affect and substance use and problems. Current findings suggest that adolescents high in anxiety sensitivity tend to prospectively experience greater depressive affect, which in turn is related to a higher likelihood of engaging in several different forms of substance use. Thus, it is possible that interventions which target AS (particularly AS cognitive concerns) may help to treat or prevent depression and substance use among adolescents. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Cardiovascular dysfunction induced by combined exposure to nicotine inhalation and high-fat diet

Smoking and high-fat diet (HFD) consumption are two modifiable risk factors for cardiovascular (CV) diseases, and individuals who are overweight or obese due to unhealthy diet are more likely to use tobacco products. In this study, we aim to investigate the combined effects of nicotine (the addictive component of all tobacco products) and HFD on CV health, which are poorly understood. C57BL/6N male mice were placed on either HFD (60 kcal% fat) or regular diet (22 kcal% fat) and exposed to air or nicotine vapor for 10-12 wk. CV function was monitored by echocardiography and radiotelemetry, with left ventricular (LV) catheterization and aortic ring vasoreactivity assays performed at end point. Mice on HFD exhibited increased heart rate and impaired parasympathetic tone, whereas nicotine exposure increased sympathetic vascular tone as evidenced by increased blood pressure (BP) response to ganglionic blockade. Although neither nicotine nor HFD alone or in combination significantly altered BP, nicotine exposure disrupted circadian BP regulation with reduced BP dipping. LV catheterization revealed that combined exposure to nicotine and HFD led to LV diastolic dysfunction with increased LV end-diastolic pressure (LVEDP). Moreover, combined exposure resulted in increased inhibitory phosphorylation of endothelial nitric oxide synthase and greater impairment of endothelium-dependent vasodilation. Finally, a small cohort of C57BL/6N females with combined exposure exhibited similar increases in LVEDP, indicating that both sexes are susceptible to the combined effect of nicotine and HFD. In summary, combined exposure to nicotine and HFD leads to greater CV harm, including both additive and new-onset CV dysfunction.NEW & NOTEWORTHY Nicotine product usage and high-fat diet consumption are two modifiable risk factors for cardiovascular diseases. Here, we demonstrate that in mice, combined exposure to inhaled nicotine and high-fat diet results in unique cardiovascular consequences compared with either treatment alone, including left ventricular diastolic dysfunction, dysregulation of blood pressure, autonomic dysfunction, and greater impairment of endothelium-dependent vasorelaxation. These findings indicate that individuals who consume both nicotine products and high-fat diet have distinctive cardiovascular risks.

E-cigarettes and arrhythmogenesis: a comprehensive review of pre-clinical studies and their clinical implications

Electronic cigarette use has grown exponentially in recent years, and while their popularity has increased, the long-term effects on the heart are yet to be fully studied and understood. Originally designed as devices to assist with those trying to quit traditional combustible cigarette use, their popularity has attracted use by teens and adolescents who traditionally have not smoked combustible cigarettes. Acute effects on the heart have been shown to be similar to traditional combustible cigarettes, including increased heart rate and blood pressure. The main components of electronic cigarettes that contribute to these arrhythmic effects are found in the e-liquid that is aerosolized and inhaled, comprised of nicotine, flavourings, and a combination of vegetable glycerin (VG) and propylene glycol (PG). Nicotine can potentially induce both ventricular and atrial arrhythmogenesis, with both the atrial and ventricular effects resulting from the interactions of nicotine and the catecholamines they release via potassium channels. Atrial arrhythmogenesis, more specifically atrial fibrillation, can also occur due to structural alterations, which happens because of nicotine downregulating microRNAs 133 and 590, both post-transcriptional growth factor repressors. Liquid flavourings and the combination of PG and VG can possibly lead to arrhythmic events by exposing users to acrolein, an aldehyde that stimulates TRPA1 that in turn causes a change towards sympathetic activation and autonomic imbalance. The design of these electronic delivery devices is constantly changing; therefore, it has proven extremely difficult to study the long-term effects on the heart caused by electronic cigarettes but will be important to understand given their rising popularity. The arrhythmic effects of electronic cigarettes appear similar to traditional cigarettes as well; however, a comprehensive review has not been compiled and is the focus of this article.

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.

Pod-based e-cigarettes versus combustible cigarettes: The impact on peripheral and cerebral vascular function and subjective experiences

INTRODUCTION

The vaping epidemic in the US has been largely attributed to the emergence of pod-based e-cigarette devices. While these devices continue to be promoted as alternatives to cigarettes, their impact on cardiovascular and behavioral outcomes remains incompletely understood. This study assessed the impact of pod-based e-cigarettes on peripheral and cerebral vascular function, along with subjective experiences among adult cigarette smokers.

METHODS

In a crossover laboratory design study, a total of 19 (e-cigarette naïve) cigarette smokers (aged 21-43 years) attended two lab sessions. In one session, participants smoked a cigarette and in the other, vaped a pod-based e-cigarette. Participants completed questions assessing subjective experiences. Peripheral macrovascular and microvascular function was assessed via brachial artery FMD and reactive hyperemia, while cerebral vascular function was assessed as the blood velocity response of the middle cerebral artery during hypercapnia. Measurements were taken before and after exposure.

RESULTS

Compared with baseline, there was a reduction in peripheral macrovascular function (indexed by FMD), following e-cigarette (pre=9.3±4.3%; post=6.4±4.1%) and cigarette use (pre=10.2±3.7%; post=6.8±3.8%; main effect of time p<0.0001). Cerebral vascular function (indexed by cerebral vasodilatory response during hypercapnia) was also reduced following e-cigarette (pre=53±19%; post=44±15%) and cigarette use (pre=54±21%; post=44±17%; main effect of time p<0.01). The magnitude of reduction in peripheral and cerebral vascular function was similar between conditions (condition × time, p>0.05). Compared with vaping an e-cigarette, participants scored higher for measures of satisfaction, taste, puff liking, and suppression of craving following smoking (p>0.05).

CONCLUSIONS

Similar to smoking, vaping a pod-based e-cigarette leads to an impairment in peripheral and cerebral vascular function while providing a reduced subjective experience compared with a cigarette among adult smokers. While these data challenge the notion that e-cigarette use is a safe and satisfactory alternative to cigarette use, large longitudinal studies are needed to assess the long-term impact of pod-based e-cigarette devices on cardiovascular and behavioral outcomes.

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.

Clinical testing of the cardiovascular effects of e-cigarette substitution for smoking: a living systematic review

Some persons who smoke have substituted e-cigarettes for tobacco cigarettes, either completely or partially. What effect does this have on cardiovascular functioning? We conducted a living systematic review on human clinical studies measuring the cardiovascular effects of e-cigarette substitution for smoking. The Scopus, PubMed, and CENTRAL Cochrane Library databases were searched on January 31 and April 29, 2021. Three secondary searches and a grey literature search were conducted. Included study designs were randomized controlled trials, quasi-experimental clinical trials, and cohort studies. Risk of bias and study quality were evaluated with the JBI Critical Appraisal tools and the Oxford Catalogue of Bias. The systematic review covered 25 studies comprising 1810 participants who smoked. Twenty studies were rated at high risk of bias, and five as some concerns. A tabular synthesis by direction of effect was conducted due to heterogeneity in the data. Nearly two-thirds of the test analyses indicated that e-cigarette use had no significance difference compared with tobacco cigarettes on heart rate, blood pressure, and in other cardiovascular tests. In two studies, participants with hypertension experienced a clinically relevant reduction in systolic blood pressure after 1 year of e-cigarette use. E-cigarette substitution incurs no additional cardiovascular risks, and some possible benefits may be obtained, but the evidence is of low to very low certainty. An update search on May 30, 2022 retrieved five studies that did not alter our conclusion.Registration PROSPERO #CRD42021239094.

Vaping and Mental Health Conditions in Children: An Umbrella Review

The e-cigarette (EC) epidemic began in the United States (US) in 2007; since 2014 EC is the most commonly used form of tobacco. However, the mental health implications of vaping are grossly unknown. The aim of this umbrella review is to provide astate-of-the-art summary of existing research concerning vaping and mental health conditions in children. Following the PRISMA Statement 2020 guidelines, a systematic search was conducted across PubMed, Cochrane Library, and Google Scholar up to April 15th, 2022 to locate relevant studies. The Joana Briggs Institute (JBI) methodology for umbrella reviews and quality appraisal tool was utilized. Six studies, pooling a total of 846,510 adolescents aged 21 years or below, were included by collating 85 primary clinical studies. Of these, 58.8% of the primary clinical studies originated in the US, with 4.7% from Canada, South Korea, and the United Kingdom each; 3.5% each from England and Taiwan; 2.4% each from Australia, France, Hawaii, Mexico, and Russia; and 1.2% each from Denmark, Greece, Hong Kong, Iceland, New Zealand, Poland, and Switzerland. Overall, significant associations were found between mental health outcomes, including depression and suicidality, among current EC users and those who had ever used EC. Compared to adolescents who had never used EC, both depression and anxiety were reportedly higher among EC users. Impulsive behaviors, reported as impulsivity, were also found to be correlated with the adoption of EC use. However, there is a lack of evidence regarding the impact of EC use on mental health outcomes in children. This umbrella review highlights the urgent need to further explore the effects of current EC use from a psychiatric and public health perspective.

Chronic health effects associated with electronic cigarette use: A systematic review

Introduction

Over the last decade, e-cigarette use has been on the rise but with growing health concerns. The objective of this systematic review was to update findings for chronic health outcomes associated with e-cigarette use from the 2018 National Academies of Sciences, Engineering, and Medicine (NASEM) report.

Methods

Three bibliographic databases were searched to identify studies comparing the chronic health effects of e-cigarette users (ECU) to non-smokers (NS), smokers, and/or dual users indexed between 31 August 2017 and 29 January 2021. Two independent reviewers screened abstracts and full texts. Data were extracted by one reviewer and verified by a second one. Outcomes were synthesized in a narrative manner using counts and based on statistical significance and direction of the association stratified by study design and exposure type. Risk of bias and certainty of evidence was assessed. The protocol was prospectively registered on Open Science Framework https://osf.io/u9btp.

Results

A total of 180 articles were eligible. This review focused on 93 studies for the 11 most frequently reported outcomes and from which 59 reported on daily e-cigarette use. The certainty of evidence for all outcomes was very low because of study design (84% cross-sectional) and exposure type (27% reported on exclusive ECU, i.e., never smoked traditional cigarettes). Overall, the summary of results for nearly all outcomes, including inflammation, immune response, periodontal and peri-implant clinical parameters, lung function, respiratory symptoms, and cardiovascular disease, suggested either non-significant or mixed results when daily ECU was compared to NS. This was also observed when comparing exclusive ECU to NS. The only notable exception was related to oral health where most (11/14) studies reported significantly higher inflammation among daily ECU vs. NS. Compared to the smokers, the exclusive-ECUs had no statistically significant differences in inflammation orperiodontal clinical parameters but had mixed findings for peri-implant clinical parameters.

Conclusions

This review provides an update to the 2018 NASEM report on chronic health effects of e-cigarette use. While the number of studies has grown, the certainty of evidence remains very low largely because of cross-sectional designs and lack of reporting on exclusive e-cigarette exposure. There remains a need for higher quality intervention and prospective studies to assess causality, with a focus on exclusive e-cigarette use.

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.

Health Effects of Electronic Cigarettes: An Umbrella Review and Methodological Considerations

E-cigarettes are often marketed as a safer alternative to combustible cigarettes. However, their health effects, especially those associated with long-term use, remain largely uncertain. We conducted an umbrella review of the cardiopulmonary and carcinogenic risks of e-cigarette use, distinguishing between short-term and long-term health effects. The search for systematic reviews was conducted across four electronic databases through 25 January 2022. Methodological quality was assessed using the AMSTAR-2 quality appraisal tool. Seventeen systematic reviews, including five meta-analyses, were included in our umbrella review. There was a clear underreporting of e-cigarette devices and e-liquid types, e-cigarette and cigarette exposure, and the health and smoking status of study participants. Overall, the findings suggest that short-term use of e-cigarettes may be associated with acute cardiopulmonary risks, although to a lesser extent than cigarette use. Long-term e-cigarette use may have pulmonary/respiratory benefits in those who switch from chronic cigarette smoking, particularly in individuals with asthma and chronic obstructive pulmonary disease (COPD). Evidence on intermediate and long-term carcinogenic effects is lacking. This umbrella review underscores the urgent need for systematic reviews with better adherence to established reporting guidelines, consistent definitions of duration of e-cigarette use, a focus on newer devices, and accounting for the impacts of former or current smoking.

Developmental Effects of Electronic Cigarette Use

Electronic cigarettes have gained widespread acceptance among adolescents and young adults. As a result of this popularity, there are concerns regarding the potential harm of primary, secondhand and thirdhand electronic cigarette exposures on fetal and postnatal development. In vitro studies have shown that constituents in electronic cigarette liquids, including nicotine, flavorings, and carrier agents can alter cellular processes and growth. Additionally, aerosolized electronic cigarette emissions have been shown to disrupt organ development and immune responses in preclinical studies. In clinical studies, an association between electronic cigarette use and frequent respiratory symptoms, greater asthma severity and impaired mucociliary clearance has been demonstrated with adolescent and young adult users of electronic cigarettes having twice the frequency of cough, mucus production, or bronchitis compared to nonusers. Along with the popularity of electronic cigarette use, secondhand electronic cigarette exposure has increased substantially; with almost one-fourth of middle and high school children reporting exposure to secondhand vapors. The health consequences of secondhand electronic cigarette exposure on children and other vulnerable populations are poorly understood but detectable levels of cotinine have been measured in nonusers. Pregnant women and their offspring are another vulnerable group at increased risk for health consequences from electronic cigarette exposure. Nicotine crosses the placenta and can disrupt brain and lung development in preclinical studies. This article will focus on the physiological and health effects associated with primary or secondhand exposure to electronic cigarettes. It is expected that with ongoing availability of electronic cigarettes as well as the accumulation of additional follow-up time for long-term outcomes, the risks associated with exposure will become better clarified. © 2022 American Physiological Society. Compr Physiol 12:3337-3346, 2022.

Polycyclic aromatic hydrocarbons associated long non-coding RNAs and heart rate variability in coke oven workers

Epidemiological studies have showed that polycyclic aromatic hydrocarbons (PAHs) were associated with heart rate variability (HRV), but the role of long non-coding RNAs (lncRNAs) in the association is unknown. We aimed to identify PAHs-related lncRNAs and assess their associations with HRV among coke oven workers. Differential lncRNAs expression between 12 exposed workers and 12 controls was tested by Human 8X60k LncRNA Arrays in discovery stage, then selected NR_024564 was validated in 353 workers using droplet digital RT-PCR. Microarray results showed that 1234 lncRNAs were downregulated with 805 lncRNAs upregulated in exposed group (≥ 2-fold change). In validation stage, no significant association was observed between NR_024564 and PAH exposure or HRV in total subjects, while urinary 2-hydroxyfluorene (2-OHFlu) was inversely related to root mean square successive difference (RMSSD). However, in current smokers, NR_024564 was inversely related to urinary 2-OHFlu, 2-hydroxyphenanthrene, 1-hydroxypyrene (1-OHP), and total PAHs metabolites (ΣOH-PAHs), of which 1-OHP accounted for the strongest estimation for interaction with smoking status (P_interaction = 0.011). Also, the positive associations of NR_024564 with RMSSD and high frequency power showed an interaction with smoking status (P_interaction = 0.034 and 0.023, respectively). Also, urinary 2-OHFlu and ΣOH-PAHs were inversely associated with RMSSD in current smokers. In addition, elevated NR_024564 was dose-responsive related to increased RMSSD in above high-PAHs groups among smokers (all P_trend < 0.05). Our results revealed that NR_024564 and its interactions with smoking status might act as novel mechanisms regulating the adverse effects of PAHs on HRV.

Judgement of valence of musical sounds by hand and by heart, a machine learning paradigm for reading the heart

The intention of the experiment is to investigate whether different sounds have influence on heart signal features in the situation the observer is judging the different sounds as positive or negative. As the heart is under (para)sympathetic control of the nervous system this experiment could give information about the processing of sound stimuli beyond the conscious processing of the subject. As the nature of the influence on the heart signal is not known these signals are to be analysed with AI/machine learning techniques. Heart rate variability (HRV) is a variable derived from the R-R interval peaks of electrocardiogram which exposes the interplay between the sympathetic and parasympathetic nervous system. In addition to its uses as a diagnostic tool and an active part in the clinic and research domain, the HRV has been used to study the effects of sound and music on the heart response; among others, it was observed that heart rate is higher in response to exciting music compared with tranquilizing music while heart rate variability and its low-frequency and high-frequency power are reduced. Nevertheless, it is still unclear which musical element is related to the observed changes. Thus, this study assesses the effects of harmonic intervals and noise stimuli on the heart response by using machine learning. The results show that noises and harmonic intervals change heart activity in a distinct way; e.g., the ratio between the axis of the ellipse fitted in the Poincaré plot increased between harmonic intervals and noise exposition. Moreover, the frequency content of the stimuli produces different heart responses, both with noise and harmonic intervals. In the case of harmonic intervals, it is also interesting to note how the effect of consonance quality could be found in the heart response.

Respiratory and Cardiovascular Health Effects of e-Cigarette Substitution: Protocol for Two Living Systematic Reviews

Background

Despite the clear risks of tobacco use, millions of people continue to smoke. Electronic nicotine delivery systems (ENDS), commonly called e-cigarettes, have been proposed as a substitute for those who are unwilling or unable to quit. Current systematic and narrative reviews on the health effects of ENDS use, particularly respiratory and cardiovascular effects, have come to differing conclusions.

Objective

We conducted two systematic reviews to critically assess and synthesize available human studies on the respiratory and cardiovascular health effects of ENDS substitution for people who smoke. The primary goal is to provide clinicians with evidence on the health effects of ENDS substitution to inform their treatment recommendations and plans. The twin goal of the reviews is to promote health literacy in ENDS users with facts on the health effects of ENDS.

Methods

These two reviews will be living systematic reviews. The systematic reviews will be initiated through a baseline review. Studies will be evaluated using the JBI quality assessment tools and a checklist of biases drawn from the Centre for Evidence Based Medicine Catalogue of Bias. A narrative synthesis is planned because of the heterogeneity of data. A search for recently published studies will be conducted every 3 months, and an updated review will be published every 6 months for the duration of the project or possibly longer.

Results

The baseline and updated reviews will be published in a peer-reviewed journal. The findings of the reviews will be reported in a white paper for clinicians and a fact sheet for people who use ENDS.

Conclusions

The substitution of ENDS for cigarettes is one way to potentially reduce the risks of smoking. Clinicians and their patients need to understand the potential benefits and possible risks of substituting ENDS for cigarettes. Our living systematic reviews seek to highlight the best and most up-to-date evidence in this highly contentious and fast-moving field of research.

Trial Registration

PROSPERO CRD42021239094; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=239094

International Registered Report Identifier (IRRID)

DERR1-10.2196/29084

Vaping and cardiac disease

Tobacco cigarette smoking is the most prevalent reversible risk factor for cardiovascular disease in the USA. Electronic cigarettes, invented as an alternative nicotine source for smokers unable or unwilling to stop smoking, have gained skyrocketing popularity, but their cardiovascular risk remains uncertain. Although data recently analysed in a Cochran report do support their superior effectiveness to other forms of nicotine replacement therapies for smoking cessation, electronic cigarettes are also frequently used by non-smokers-especially high school students. There are no long-term outcome studies on the cardiovascular risk of vaping electronic cigarettes, but the effects of electronic cigarettes on known risk factors for cardiovascular disease, including neurohumoural activation, oxidative stress and inflammation, endothelial function and thrombosis, have been studied. In this review, we summarise evidence in humans that supports the notion that while electronic cigarettes may be less harmful than traditional cigarettes, they are not harmless. Additionally, the increasing popularity of vaping marijuana with its unknown cardiovascular risks as well as the outbreak in 2019 of EVALI (electronic cigarette, or vaping, product use-associated lung injury) related to bootlegged vaping products raise further concerns. Before physicians can confidently advise their smoking patients about the role of electronic cigarettes as a means of smoking cessation to lower cardiovascular risk, improved regulation and quality control is necessary.

The Smoking Paradox: A Twist in the Tale of Vasospastic Angina

Cigarette smoking is undoubtedly the single most important risk factor and trigger for vasospastic angina, a condition also known as Prinzmetal angina secondary to coronary artery vasospasm. Even decades before vasospastic angina was first described by Dr. Myron Prinzmetal and his colleagues in 1959, there had been suspected connections between smoking and coronary artery vasospasm in what was alluded to then as "tobacco angina." The intimate relationship between smoking and vasospastic angina has since been extensively researched and validated through decades of epidemiological and clinical studies. The fact that smoking would aggravate vasospastic angina comes with very little surprise, as it has been shown to adversely impact many of the disease processes thought to underlie vasospastic angina, including autonomic dysfunction, endothelial dysfunction, smooth muscle hyperactivity, and genetic susceptibility. While avoidance of smoking is the first logical step in managing smokers with vasospastic angina, there have been reported cases of vasospastic angina paradoxically triggered by smoking cessation or relieved with smoking resumption or nicotine replacement therapy. Thus, there appears to be patient-specific factors that could significantly alter the close connection between smoking and vasospastic angina, warranting further mechanistic investigations. In this review, we will examine this complicated relationship between smoking and vasospastic angina from multiple perspectives (historical, mechanistic, and clinical) and call attention to the "smoking paradox," which, with further elucidation, may provide additional insight into the complex mechanisms of VSA and potentially new strategies to treat medically refractory VSA, at least in selected individuals.

α3* Nicotinic Acetylcholine Receptors in the Habenula-Interpeduncular Nucleus Circuit Regulate Nicotine Intake

Allelic variation in CHRNA3, the gene encoding the α3 nicotinic acetylcholine receptor (nAChR) subunit, increases vulnerability to tobacco dependence and smoking-related diseases, but little is known about the role for α3-containing (α3*) nAChRs in regulating the addiction-related behavioral or physiological actions of nicotine. α3* nAChRs are densely expressed by medial habenula (mHb) neurons, which project almost exclusively to the interpeduncular nucleus (IPn) and are known to regulate nicotine avoidance behaviors. We found that Chrna3^tm1.1Hwrt hypomorphic mice, which express constitutively low levels of α3* nAChRs, self-administer greater quantities of nicotine (0.4 mg kg^-1 per infusion) than their wild-type littermates. Microinfusion of a lentivirus vector to express a short-hairpin RNA into the mHb or IPn to knock-down Chrna3 transcripts markedly increased nicotine self-administration behavior in rats (0.01-0.18 mg kg^-1 per infusion). Using whole-cell recordings, we found that the α3β4* nAChR-selective antagonist α-conotoxin AuIB almost completely abolished nicotine-evoked currents in mHb neurons. By contrast, the α3β2* nAChR-selective antagonist α-conotoxin MII only partially attenuated these currents. Finally, micro-infusion of α-conotoxin AuIB (10 μm) but not α-conotoxin MII (10 μm) into the IPn in rats increased nicotine self-administration behavior. Together, these data suggest that α3β4* nAChRs regulate the stimulatory effects of nicotine on the mHb-IPn circuit and thereby regulate nicotine avoidance behaviors. These findings provide mechanistic insights into how CHRNA3 risk alleles can increase the risk of tobacco dependence and smoking-related diseases in human smokers.SIGNIFICANCE STATEMENT Allelic variation in CHRNA3, which encodes the α3 nicotinic acetylcholine receptor (nAChR) subunit gene, increases risk of tobacco dependence but underlying mechanisms are unclear. We report that Chrna3 hypomorphic mice consume greater quantities of nicotine than wild-type mice and that knock-down of Chrna3 gene transcripts in the habenula or interpeduncular nucleus (IPn) increases nicotine intake in rats. α-Conotoxin AuIB, a potent antagonist of the α3β4 nAChR subtype, reduced the stimulatory effects of nicotine on habenular neurons, and its infusion into the IPn increased nicotine intake in rats. These data suggest that α3β4 nAChRs in the habenula-IPn circuit regulate the motivational properties of nicotine.

Vaping Instead of Cigarette Smoking: A Panacea or Just Another Form of Cardiovascular Risk?

Since 2007, the electronic cigarette (EC), with its increasingly diverse array of device options, has gained popularity both among long-term tobacco cigarette (TC) smokers and among never-smoking youth. The absence of a number of known toxic by-products of TC smoking has helped cultivate the perception that ECs are healthy. However, an expanding literature has provided concerning evidence that a number of EC constituents, including nicotine, and their thermal degradation by-products may have adverse effects, including cardiovascular effects. In this review, we discuss the cardiovascular risks associated with EC vaping and compare this risk profile with TC smoking. Acknowledging the dynamic nature of EC vaping, we will focus on the latest developments, including the introduction of the pod-like device, which is the most popular EC device used today. We discuss the implications of a new, unique, nicotine chemistry that mimics the efficient and addictive nicotine delivery of TCs. Furthermore, we touch on the outbreak of the lethal lung disease associated with ECs, which exposed the lack of quality control in the EC industry. Along the way, we will identify the limitations of current knowledge and provide suggestions for future research. Overall, we conclude that although ECs may once have held promise as part of a harm-reduction strategy in people who smoke lethal TCs, this role has been largely offset by the unconscionable marketing to our youth, in addition to a failure of regulation and enforcement, leading to significant harm, especially in never-smokers who use them.

Acute effects of electronic cigarettes on arterial pressure and peripheral sympathetic activity in young nonsmokers

Electronic cigarettes (e-cigarettes) are marketed as an alternative to smoking for those who want to decrease the health risks of tobacco. Tobacco cigarettes increase heart rate (HR) and arterial pressure, while reducing muscle sympathetic nerve activity (MSNA) through sympathetic baroreflex inhibition. The acute effects of e-cigarettes on arterial pressure and MSNA have not been reported: our purpose was to clarify this issue. Using a randomized crossover design, participants inhaled on a JUUL e-cigarette containing nicotine (59 mg/mL) and a similar placebo e-cigarette (0 mg/mL). Experiments were separated by ∼1 mo. We recorded baseline ECG, finger arterial pressure (n = 15), and MSNA (n = 10). Subjects rested for 10 min (BASE) and then inhaled once every 30 s on an e-cigarette that contained nicotine or placebo (VAPE) for 10 min followed by a 10-min recovery (REC). Data were expressed as Δ means ± SE from BASE. Heart rate increased in the nicotine condition during VAPE and returned to BASE values in REC (5.0 ± 1.3 beats/min nicotine vs. 0.1 ± 0.8 beats/min placebo, during VAPE; P < 0.01). Mean arterial pressure increased in the nicotine condition during VAPE and remained elevated during REC (6.5 ± 1.6 mmHg nicotine vs. 2.6 ± 1 mmHg placebo, during VAPE and 4.6.0 ± 1.7 mmHg nicotine vs. 1.4 ± 1.4 mmHg placebo, during REC; P < 0.05). MSNA decreased from BASE to VAPE and did not restore during REC (-7.1 ± 1.6 bursts/min nicotine vs. 2.6 ± 2 bursts/min placebo, during VAPE and -5.8 ± 1.7 bursts/min nicotine vs. 0.5 ± 1.4 bursts/min placebo, during REC; P < 0.05). Our results show that acute e-cigarette usage increases mean arterial pressure leading to a baroreflex-mediated inhibition of MSNA.NEW & NOTEWORTHY The JUUL e-cigarette is the most popular e-cigarette in the market. In the present study, inhaling on a JUUL e-cigarette increased mean arterial pressure and heart rate, and decreased muscle sympathetic nerve activity (MSNA). In contrast, inhaling on a placebo e-cigarette without nicotine elicited no sympathomimetic effects. Although previous tobacco cigarette studies have demonstrated increased mean arterial pressure and MSNA inhibition, ours is the first study to report similar responses while inhaling on an e-cigarette. Listen to this article's corresponding podcast at @ https://ajpheart.podbean.com/e/aerosolized-nicotine-and-cardiovascular-control/.

The Acute Effects of Electronic Cigarette Vaping and Tobacco Cigarette Smoking on Choroidal Thickness in Young, Healthy, Habitual, Dual Smokers

The present study aims to evaluate and compare the acute effects of tobacco cigarettes (TC) smoking and electronic cigarette (EC) vaping on foveal and choroidal thickness (CT) in young, healthy, dual smokers. Participants underwent four trials: 5 min TC; 5 min EC; 30 min EC; and 60 min nothing (sham trial). Scans before and immediately after each trial were obtained using spectral domain optical coherence tomography with the enhanced depth imaging mode. Changes in central foveal thickness (CFT), subfoveal choroidal thickness (SFCT), and CT at fourother points, 500 μm and 1000 μm temporally and nasally to the fovea, were measured. Forty-seven participants (33 male, 14 female; mean age 24.85 ± 1.57 years) were included. They smoked 13.53 ± 5.27 TCs/day for 6 ± 2.3 years and vaped ECs for the past 2.4 ± 1.08 years. We did not observe any statistically significant change in SFCT, CFT, and CT of the other points after any of the fourtrials. The acute changes in CFT and CT after EC vaping or TC smoking did not differ significantly compared to the sham trial. Smoking and vaping does not seem to result in statistically significant acute alterations in foveal and CT in young, dual smokers.

Beclin1 Haploinsufficiency accentuates second-hand smoke exposure -induced myocardial Remodeling and contractile dysfunction through a STING-mediated mechanism

Second-hand smoking evokes inflammation and cardiovascular diseases. Recent evidence has revealed a pivotal role for deranged autophagy in smoke exposure-induced cardiac anomalies. This study evaluated the impact of haploinsufficiency of the mTOR-independent autophagy protein Beclin1 on side-stream smoke exposure-induced cardiac anomalies and mechanism(s) involved. Adult WT and Beclin1 haploinsufficiency (Becn^+/-) mice were exposed to cigarette smoke for 1 h daily for 90 days. Echocardiographic, cardiomyocyte function, intracellular Ca²⁺, autophagy, mitophagy, apoptosis and inflammation were examined. DHE staining was employed to evaluate O₂^- level. Our data revealed that Beclin1 deficiency exacerbated smoke exposure-induced myocardial anomalies in geometry, fractional shortening, cardiomyocyte function, intracellular Ca²⁺ handling, TEM ultrastructure, and inflammation along with pronounced apoptosis and O₂^- production. Side-stream smoke provoked excessive autophagy/mitophagy, mtDNA release, and activation of innate immune response signals cyclic GMP-AMP synthase (cGAS) and its effector - stimulator of interferon genes (STING), the effect was abolished or unaffected by Becn haploinsufficiency. STING phosphorylation was overtly promoted by smoke exposure in Becn^+/- mice. Smoke exposure also suppressed phosphorylation of mTOR although it facilitated that of ULK1 in both groups. In vitro data revealed that inhibition of cGAS or STING failed to affect smoke extract-induced mitophagy although they abrogated smoke extract-induced cardiomyocyte dysfunction except cGAS inhibition in Becn^+/- mice. These data suggest that Beclin1 is integral in the maintenance of cardiac homeostasis under side-stream smoke exposure via a STING-mediated mechanism.

Differential effects of tobacco cigarettes and electronic cigarettes on endothelial function in healthy young people

Tobacco cigarette (TC) smoking has never been lower in the United States, but electronic cigarette (EC) vaping has reached epidemic proportions among our youth. Endothelial dysfunction, as measured by flow-mediated vasodilation (FMD) is a predictor of future atherosclerosis and adverse cardiovascular events and is impaired in young TC smokers, but whether FMD is also reduced in young EC vapers is uncertain. The aim of this study in otherwise healthy young people was to compare the effects of acute and chronic tobacco cigarette (TC) smoking and electronic cigarette (EC) vaping on FMD. FMD was compared in 47 nonsmokers (NS), 49 chronic EC vapers, and 40 chronic TC smokers at baseline and then after EC vapers (n = 31) and nonsmokers (n = 47) acutely used an EC with nicotine (ECN), EC without nicotine (EC0), and nicotine inhaler (NI) at ~4-wk intervals and after TC smokers (n = 33) acutely smoked a TC, compared with sham control. Mean age (NS, 26.3 ± 5.2 vs. EC, 27.4 ± 5.45 vs. TC, 27.1 ± 5.51 yr, P = 0.53) was similar among the groups, but there were more female nonsmokers. Baseline FMD was not different among the groups (NS, 7.7 ± 4.5 vs. EC:6.6 ± 3.6 vs. TC, 7.9 ± 3.7%∆, P = 0.35), even when compared by group and sex. Acute TC smoking versus control impaired FMD (FMD pre-/postsmoking, -2.52 ± 0.92 vs. 0.65 ± 0.93%∆, P = 0.02). Although the increase in plasma nicotine was similar after EC vapers used the ECN versus TC smokers smoked the TC (5.75 ± 0.74 vs. 5.88 ± 0.69 ng/mL, P = 0.47), acute EC vaping did not impair FMD. In otherwise healthy young people who regularly smoke TCs or ECs, impaired FMD compared with that in nonsmokers was not present at baseline. However, FMD was significantly impaired after smoking one TC, but not after vaping an equivalent "dose" (estimated by change in plasma nicotine) of an EC, consistent with the notion that non-nicotine constituents in TC smoke mediate the impairment. Although it is reassuring that acute EC vaping did not acutely impair FMD, it would be dangerous and premature to conclude that ECs do not lead to atherosclerosis.NEW & NOTEWORTHY In our study of otherwise healthy young people, baseline flow-mediated dilation (FMD), a predictor of atherosclerosis and increased cardiovascular risk, was not different among tobacco cigarette (TC) smokers or electronic cigarette (EC) vapers who had refrained from smoking, compared with nonsmokers. However, acutely smoking one TC impaired FMD in smokers, whereas vaping a similar EC "dose" (as estimated by change in plasma nicotine levels) did not. Finally, although it is reassuring that acute EC vaping did not acutely impair FMD, it would be premature and dangerous to conclude that ECs do not lead to atherosclerosis or increase cardiovascular risk.

Vaping Cardiovascular Health Risks: an Updated Umbrella Review

Purpose of Review

Modified risk products (MRP) such as electronic vaping cigarettes (EVC) and heat-not-burn cigarettes (HNBC) are alternatives to traditional combustion cigarettes (TCC) with an expanding consumer base. Yet, their cardiovascular health risks are still unclear. We aimed to summarize the evidence base on this topic by conducting an updated umbrella review.

Recent Findings

We identified 7 systematic reviews, totaling 183 studies and reports, ranging from in vitro and in animal studies to clinical studies in apparently healthy volunteers and patients at risk of cardiovascular disease. Overall, acute EVC use was associated with several toxic effects at molecular, cellular, tissue, organ, and system level. In addition, EVC impacted adversely on blood pressure (BP) management, caused tachycardia, and worsened arterial stiffness. Finally, EVC use was associated with an increased risk of adverse clinical events, including atrial fibrillation and myocardial infarction, even if the causal link is still debated. Most reviews highlighted that the detrimental impact of EVC was of lesser magnitude of that of TCC. In addition, the differential impact of liquids and nicotine was not clearly disentangled. Finally, no review included studies on HNBC.

Summary

The present umbrella review suggests that EVC, and likely HNBC, despite clearly causing an increase in overall cardiovascular risk, may represent a temporary lesser evil than TCC in a risk-reduction or risk-modification strategy, aiming for eventual abstinence from all tobacco or nicotine products.