Cardiovascular effects of electronic cigarettes

Introduction:
This text provides an overview of the potential adverse effects of electronic cigarettes (ECs) on cardiovascular health. It describes the constituents, level of exposure of toxicants, and potential mechanisms of cardiovascular toxicity of ECs compared with tobacco cigarettes. additionally, the text reviews available human data on cardiovascular effects of ECs to assess likely cardiovascular harm and provides relevant advice for clinicians treating patients with cardiovascular disease (CVD) who are seeking to use ECs to aid in smoking cessation.

Key points:

* ECs generate a vapor or aerosol that delivers nicotine for inhalation without combusting tobacco.
* ECs deliver neither carbon monoxide nor most of the thousands of combustion products found in cigarette smoke.
* Propylene glycol and vegetable glycerin, when heated, can form thermal dehydration products such as acetaldehyde, formaldehyde, propylene oxide, acetol, allyl alcohol, glyoxal, and methylglyoxal.
* ECs generate both highly reactive, short-lived free radicals, and stable, long-lived free radicals.
* Particles generated by ECs are reported to have a bimodal size distribution, including both nanoparticles and submicron particles.
* Most e-liquids are flavoured, and thousands of different flavours are currently available.
* Nicotine delivered via EC aerosol enters the mouth during the particle phase, and diffuses out of the particles into the vapour phase in the airways.
* Cigarette smoking results in intermittent peaks and troughs of nicotine in the blood throughout the day, while EC users tend to spread out their puffs more evenly throughout the day leading to lower blood nicotine levels and lesser magnitude of arterial spikes.

Main message:
The text highlights that although ECs might pose some cardiovascular risk, particularly in people with pre-existing CVD, the risk is less than that of cigarette smoking. If the adoption of ECs with appropriate design and safety regulations can reduce the prevalence of smoking, cardiovascular health is likely to improve in this population. however, a possible disadvantage of increased EC use is persistent dual use with tobacco cigarettes, which might result in lower rates of smoking cessation and an adverse effect on cardiovascular health.

Benowitz, Neal L., and Joseph B. Fraiman. “Cardiovascular Effects of Electronic Cigarettes.” Nature Reviews Cardiology 14, no. 8 (august 2017): 447–56. https://doi.org/10.1038/nrcardio.2017.36.