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

Abstract

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, flavorings, and a combination of vegetable glycerin and propylene glycol. 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 with 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 flavorings and the combination of propylene glycol and vegetable glycerin 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.

A case report of vaping associated sudden cardiac arrest in a young healthy patient

“…Electronic cigarettes were initially introduced as an alternative to conventional tobacco cigarettes to attract consumers to a ‘healthier’ substitute 1 , 2 , 4 . The reasoning behind the claim that electronic cigarettes are ‘healthier’ lies in the assumption that fewer toxic chemicals are being released during aerosolization than tobacco combustion.…”

“…Electronic cigarettes contain three components: a heating element, a power source (such as a battery), and a solvent or liquid (e-liquid), which undergoes aerosolization and is ultimately inhaled 4 , 6 . The amount of aerosolized inhaled content is based on not only the actions of the user but also the voltage of the e-cigarette and the e-liquid ingredients.…”

“…The amount of aerosolized inhaled content is based on not only the actions of the user but also the voltage of the e-cigarette and the e-liquid ingredients. While the makeup of the inhaled aerosolized vapor varies, it generally includes a combination of a flavoring agent and a solvent, such as vegetable glycerin (VG), propylene glycol (PG), or a combination thereof, with or without nicotine 4 , 7 . Inhaled toxicants are also generated through the thermolysis of e-liquid content, comprised of aldehydes, volatile organic compounds, and metals 4 , 8 .…”

“…Given the novelty and continuous evolution of e-cigarettes, literature evaluating the electrophysiologic effects of non-nicotine vaping remains limited, with the majority being preclinical studies 4 . In a study evaluating the electrophysiologic effects of aerosols generated from nicotine-free e-cigarettes in mice, ventricular tachyarrhythmias were noted to increase significantly upon exposure to nicotine-free PG while exposure to VG aerosols elicited bradyarrhythmias and repolarization changes 9 .…”

“…In a study evaluating the electrophysiologic effects of aerosols generated from nicotine-free e-cigarettes in mice, ventricular tachyarrhythmias were noted to increase significantly upon exposure to nicotine-free PG while exposure to VG aerosols elicited bradyarrhythmias and repolarization changes 9 . Given that both the sympathetic and parasympathetic nervous systems regulate heart rate, abnormalities noted in heart rate variation reflect an imbalance of autonomic functioning 4 . These outcomes suggest that there may be a risk of cardiovascular electrophysiologic disturbances resulting from autonomic abnormalities resulting in proarrhythmic states manifesting as lengthened ventricular repolarization, accelerated atrioventricular conduction, decreased heart rate variability, and increased ventricular arrhythmias 9 .…”