A new study from University of Louisville researchers in the Christina Lee Brown Envirome Institute has found that exposure to e-cigarette aerosols can cause heart arrhythmias in animal models -; both in the form of premature and skipped heart beats. [...] The researchers tested the cardiac impacts of inhaled e-cigarette aerosols solely from the main two ingredients in e-liquids (nicotine-free propylene glycol and vegetable glycerin) or from flavored retail e-liquids containing nicotine. They found 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.