In a study from UC San Francisco, scientists found e-cigarettes and marijuana have harmful effects on the heart similar to those caused by tobacco cigarettes, opening the door to abnormal heart rhythms.
They found that cigarettes, e-cigarettes, and marijuana greatly interfere with the electrical activity, structure, and neural regulation of the heart.
For the heart to work well, it must pump blood efficiently and with the correct timing. The heart has its own electrical control system resulting from nerves that control it.
It also has the ability of electrical impulses to move through the heart muscle in a way that synchronizes the entire heart to correctly time the pumping.
If parts of the heart don’t correctly handle the electrical signals, then different regions of the heart act asynchronously—essentially fighting against each other, rather than functioning as a single efficient pump, resulting in arrhythmias that can be life-threatening.
Smoking tobacco leads to several kinds of harmful heart effects, including increasing the chances of arrhythmias.
E-cigarettes and heated tobacco products (sometimes called heat-not-burn products) have become popular because the public perceives them as being less harmful than smoking.
Similarly, legal recreational marijuana has become more common in recent years and is also frequently viewed by the public as being safer than smoking tobacco.
In this study, researchers exposed rats for eight weeks to a single daily session of exposure to Marlboro Red cigarette smoke, aerosol (“vapor”) from the popular e-cigarette JUUL, aerosol from the heated tobacco product IQOS, smoke from marijuana cigarettes, and smoke from modified marijuana that lacks all cannabinoids, compared to just air.
The exposures modeled a single session of actual smoking/vaping:
The rats inhaled the smoke or aerosol for five seconds twice a minute for five minutes, with clean air in between the smoke inhalations. This was done once per day for five days/week for eight weeks.
The team found during that time, the heart function in the rats exposed to the products (but not air) got progressively worse and blood pressure increased.
At the end of the study, they found that all the products led to increased scarring in the heart, a decrease in the number of blood vessels, a change in the type of nerves found in the heart, a reduction in the important ability to vary heart rate, and a higher likelihood of developing arrhythmias.
The team says all of these tobacco and marijuana products had similar effects.
And what’s really striking is that this was caused by a single realistic smoking/vaping session per day.
The results are consistent with various reports from the medical literature about heart rhythm disturbances in users of e-cigarettes or marijuana.
The observation of various physical disturbances in the heart, like the scarring and the nerve changes, suggests a similar explanation, despite the differences in nicotine or cannabinoid content.
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The study was conducted by Huiliang Qiu et al and published in the journal Heart Rhythm.
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