LOUISVILLE, Ky. — A recent study by University of Louisville researchers shows that exposure to e-cigarette aerosols can cause heart arrhythmias in animal models, both as premature and skipped heartbeats.
The study, which published Tuesday, Oct. 25 in Nature Communications, shows exposure to certain e-cigarette ingredients can promote 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.”
The researchers tested two ingredients specifically from e-cigarette liquids, nicotine-free propylene glycol and vegetable glycerin, or from flavored retail e-liquids containing nicotine. The study showed that all e-cigarette aerosols slowed the animals' heart rate during puff exposures, then sped up afterward as heart rate variability declined, showing flight-or-fight stress responses.
The e-cigarette puffs from a menthol-flavored e-liquid or from propylene glycol also caused ventricular arrhythmias and other irregularities.
"The findings 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," said Aruni Bhatnagar, a professor in the UofL Division of Environmental Medicine. "This is highly concerning given the rapid growth of e-cigarette use, particularly among young people."
About one in seven high school students (14.1%) reported earlier this year using e-cigarettes during the previous 30 days, according to a survey by the Food and Drug Administration and Centers for Disease Control and Prevention. The survey found that 85% of middle and high school students who vape use flavored e-cigarettes. Fruit flavors were the most popular at 69%, followed by candy, dessert or other sweets flavors (38%), mint (29%) and menthol (27%).
While the interest in e-cigarettes has increased over time, its health effects have been debated. UofL researchers said since vaping does not involve combustion, it exposes users and bystanders to little if any carbon monoxide, tar or cancer-causing nitrosamines compared with conventional cigarettes. But e-cigarettes can deliver aldehydes, particles and nicotine at levels comparable to combustible cigarettes.
“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.