Aerosols produced by e-cigarettes can temporarily disrupt heart function by causing heart rhythm disturbances in mice, a study in Nature Communications reveals.
“Our findings demonstrate that short-term exposure to e-cigarettes can destabilize heart rhythm through specific chemicals within e-liquids,” said Alex Carll, a University of Louisville professor and study leader. “These findings suggest that the use of e-cigarettes with certain flavors or solvent carriers can alter the electrical conduction of the heart and lead to arrhythmias. These effects could increase the risk of atrial or ventricular fibrillation and sudden cardiac arrest.”
Electronic cigarettes release nicotine without burning tobacco. As a result, e-cigarette aerosol contains far less carbon monoxide, tar, and carcinogenic compounds than cigarette smoke, leading e-cigarettes to be thought of as less harmful. However, the impact of e-cigarette aerosols on cardiac function and the roles of some of its components remain relatively unexamined.
The authors of this work have analyzed mice to study the real-time effects of e-cigarette aerosols on the electrical properties of the heart.
The use of electronic cigarettes with certain flavors or solvent vehicles can alter the electrical conduction of the heart and cause arrhythmias
Alex Carll
University of Louisville
Researchers at the University of Louisville (USA) conducted a series of experiments in which they exposed mice to 5 different e-cigarette aerosols, the primary smoke from 2 different reference cigarettes, and acrolein (a gas produced by e-cigarettes and cigarettes) with each experiment involving 6 to 8 mice.
The objective, explains Regina Dalmau, a cardiologist at the La Paz University Hospital in Madrid, to the Science Media Center, was to analyze the effect of different aerosols on the electrophysiological properties of the myocardial cell, corroborating previous evidence that attributed to these aerosols a potential effect on the autonomic regulation and showing proarrhythmic effects with the capacity to induce ventricular arrhythmias, which are potentially malignant.
Mice were then monitored during the inhalation challenge, after challenge, first between 4 to 9 minutes after each challenge, and then from 9 to 28 minutes after the final challenge.
It was discovered that inhalation of e-cigarette aerosols induces cardiac arrhythmias, alters ventricular repolarization, and alters heart rate in miceall through modulation of the autonomic nervous system during exposure.
The authors found that several of the effects, including increases in heart rate, lingered late after exposure. However, others remained comparable at levels shortly after exposure.
This work adds to a growing body of evidence about the potential toxicity and health impacts of e-cigarettes.
“The data is important because it provides new evidence about the relationship between e-cigarette use and its role in normal heart rhythms, something we didn’t know before,” he explains. Aruni Bhatnagar. “This is very concerning given the rapid growth in e-cigarette use, particularly among youth.”
The authors suggest that the nature and magnitude of these responses may depend on the chemicals in the e-liquids, such as nicotine, solvents, and flavors. Menthol-flavored e-liquids, for example, have been shown to affect atrial conduction (the conduction of electrical impulses through the heart’s atria).
In addition, e-cigarette solvents were found to alter heart rhythm more overtly in male than female mice, suggesting a role for biological sex. However, only 4 female mice were used in these analyses, and the authors point out the need for caution in interpreting these findings.
Researchers acknowledge that responses seen in rodents may be different than those seen in humans. They also note that repeated exposure to e-cigarette aerosols can lead to tolerance in humans, reducing cardiac responses, especially in adults with a history of smoking.
However, they conclude, “data showing that specific ingredients in e-cigarette liquids promote arrhythmias indicate that there is an urgent need for more research on the cardiac effects of these components in both animals and humans.”