A new study conducted at the University of California, Los Angeles, found that if non-smokers use one electronic cigarette that contains nicotine, they experience a rise in adrenaline levels in their heart; however, if the e-cigarette is nicotine-free, there was no increase in the levels of adrenaline.
Unlike conventional cigarettes, e-cigs possess no tobacco or combustion and has no smoke. Instead, these devices provide nicotine with flavoring and other chemicals in a vapor.
Dr. Holly R. Middlekauff, senior author of the and Professor of medicine (cardiology) and physiology at the David Geffen School of Medicine at UCLA explained that in comparison with the tar of tobacco cigarette smoke, e-cigarettes deliver fewer carcinogens. But the safety of these kinds of cigarettes is in question.
Prior research had indicated raised sympathetic nerve activity in chronic e-cig users, increasing the adrenaline directed to the heart and these users are more vulnerable to oxidative stress. Both of these factors increase the risk of a heart attack.
The UCLA study objective was to find whether the above mentioned events are causes due to nicotine.
The team of researchers used the "heart rate variability" technique, acquired from a prolonged, non-invasive heart rhythm recording that by calculating the degree of variability in the time between heartbeats, indicated the amount of adrenaline on the heart.
This technique had been used in previous studies to find the link between increased adrenaline activity in the heart and cardiac risk.
Middlekauff commented that the people with or without known heart disease who shows a pattern of increased levels of adrenaline in the heart possess an increased risk of death.
In the study, which is the first to separate nicotine from other the non-nicotine components to focus on the impact of e-cigarettes on human heart, 33 healthy non-smoker adults (of both tobacco cigarette and e-cigarettes) were examined.
The participants were asked to use an e-cigarette without nicotine or an empty 'sham' device and an e-cigarette with nicotine on separate days. Their cardiac adrenaline activity was measured using heart rate variability and blood samples’ oxidative stress was measured by the enzyme plasma paraoxonase (PON1).
The findings associated with the abnormal heart rate variability suggested that adrenaline levels are increased by the use of e-cigarettes with nicotine and not with e-cigarettes without nicotine.
The researchers identified no changes in oxidative stress when exposed to e-cigarettes with or without nicotine.
However, according to Middlekauff, the number of markers studied for oxidative stress were not enough sufficient for causal effect, and therefore further studies are required.
She commented that the findings are contrary to the concept inhaled nicotine is safe. She also expressed hope that the study might discourage nonsmokers from taking up electronic cigarettes.