Researchers from the University of Louisville’s Christina Lee Brown Envirome Institute found that exposure to the aerosols from e-cigarettes could cause both premature and skipped heartbeats in animals.

This happened when testing the main two ingredients in e-liquids (nicotine-free propylene glycol and vegetable glycerin), and flavored retail e-liquids containing nicotine.

“Short-term exposure to e-cigarettes can destabilize heart rhythm through specific chemicals within e-liquids,” said study author Alex Carll, an assistant professor at the institute. “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.”

While vaping does not involve combustion, thus exposing users and bystanders to little if any carbon monoxide, tar or cancer-causing nitrosamines, these e-cigarettes can deliver aldehydes, particles, and nicotine at levels comparable to conventional cigarettes.