Some cardiac effects of e-cigarette ingredients are similar to or worse than conventional cigarettes.
Exposure to e-cigarette aerosols can cause heart arrhythmias in animal models — both in the form of premature and skipped heartbeats. These are the findings of a new study from University of Louisville (UofL) researchers in the Christina Lee Brown Envirome Institute. Published on October 25 in Nature Communications, the research suggests that exposure to specific chemicals within e-cigarette liquids (e-liquids) promotes arrhythmias and cardiac electrical dysfunction.
“Our findings demonstrate that short-term exposure to e-cigarettes can destabilize heart rhythm through specific chemicals within e-liquids,” said Alex Carll, assistant professor in the UofL Department of Physiology who led the study. “These findings suggest that e-cigarette use involving certain flavors or solvent vehicles may disrupt the heart’s electrical conduction and provoke arrhythmias. These effects could increase the risk for atrial or ventricular fibrillation and sudden cardiac arrest.”
Heart Rate Changes from E-Cigarette Aerosols
The cardiac impacts of inhaled e-cigarette aerosols solely from the two main ingredients in e-liquids (nicotine-free propylene glycol and vegetable glycerin) or from flavored retail e-liquids containing nicotine were tested by the scientists. They discovered that for all e-cigarette aerosols, the animals’ heart rate slowed during puff exposures and sped up afterwards as heart rate variability declined, indicating fight-or-flight stress responses. Additionally, e-cigarette puffs from a menthol-flavored e-liquid or from propylene glycol alone caused ventricular arrhythmias and other conduction irregularities in the heart.
Conducted in collaboration with Daniel Conklin and Aruni Bhatnagar, professors in the UofL Division of Environmental Medicine, this work adds to a growing body of research on the potential toxicity and health impacts of e-cigarettes reported by the American Heart Association Tobacco Regulation and Addiction Center, for which UofL serves as the flagship institute.
“The findings of this study are important because they provide fresh evidence that the use of e-cigarettes could interfere with normal heart rhythms — something we did not know before,” Bhatnagar said. “This is highly concerning given the rapid growth of e-cigarette use, particularly among young people.”
Concerns Over E-Cigarette Popularity and Health Risks
As e-cigarette use has grown nationwide, many people have been debating the potential advantages and harms of vaping. Vaping exposes users and bystanders to little if any carbon monoxide, tar or cancer-causing nitrosamines compared with conventional cigarettes, because it does not involve combustion. However, e-cigarettes can deliver aldehydes, particles, and nicotine at levels comparable to combustible cigarettes. Vaping might help smokers quit combustible cigarettes, but the appeal and addictiveness of e-cigarettes may encourage youth to vape amidst unknown long-term risks or take up smoking. Before the COVID-19 pandemic, more than 25% of high schoolers and 10% of middle schoolers in the U.S. reported using e-cigarettes.
Additional research by Carll and Matthew Nystoriak, an associate professor of medicine at UofL, to determine the effects of vape flavorings on the heart recently received $3.6 million in research funding from the National Institutes of Health.
“Our team’s findings that specific ingredients in e-cigarette liquids promote arrhythmias indicates there is an urgent need for more research into the cardiac effects of these components in both animals and humans,” Carll said.
Reference: “E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice” by Alex P. Carll, Claudia Arab, Renata Salatini, Meredith D. Miles, Matthew A. Nystoriak, Kyle L. Fulghum, Daniel W. Riggs, Gregg A. Shirk, Whitney S. Theis, Nima Talebi, Aruni Bhatnagar and Daniel J. Conklin, 25 October 2022, Nature Communications.
DOI: 10.1038/s41467-022-33203-1
Research reported in this publication was supported by the National Heart, Lung, And Blood Institute (NHLBI) of the National Institutes of Health (NIH) and the Food and Drug Administration (FDA) Center for Tobacco Products (CTP) under Award Number R01HL147353 (A.P.C.), R01HL163818 (A.P.C. and M.A.N.), U54HL120163 (A.B.), and R01HL122676 (D.J.C.), the National Institute of General Medical Sciences of the NIH under Award Number P30GM127607 (A.B.), the Jewish Heritage Fund for Excellence (M.A.N. and A.P.C.), a Fellowship from the American Heart Association (AHA) Tobacco Regulation and Addiction Center (AHA FX-ATRAC-UL1-05; A.P.C.), and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) Scholarship – Process no {88881.131525/2016-01} (C.A. and R.S.). Research reported in this publication was supported by NHLBI and FDA Center for Tobacco Products (CTP). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, the FDA, or the AHA.
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