In a small group of healthy young people who did not smoke or vape, the vaping of a nicotine-free e-cigarette (e-cigarette) caused transient changes in blood vessels similar to those seen in early atherosclerosis,  The acute changes that was seen after one-time vaping – inhaling and exhaling the evaporated aerosol mist from the heated liquid in a battery-powered e-cigarette – suggesting that repeated vaping will lead to chronic vascular endothelial dysfunction, say the authors of this MRI study.
The study by Alessandra Caporale, PhD, a postdoctoral researcher from the Laboratory of Structural, Physiologic and Functional Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, and colleagues, was published online August 20 in Radiology .
The study used nicotine-free e-cigarettes; therefore, the findings shatter any false belief that only the nicotine in e-cigarettes is harmful to health.
"Endothelial dysfunction ̵
"The damage of cigarettes is obviously well known," Wehrli summed up, "but what was not well known [and what was shown in this study] was that e-cigarettes – although advertised as relatively harmless – could actually eventually cause harm that similar to cigarettes and not related to nicotine. "
Parents of students in secondary and high school, whose use of e-cigarettes has increased dramatically, should be aware of EES injuries, Wehrli and Caporale emphasized.
The many flavors that e-cigarettes come in "attract young people and potentially attract them to potential lifelong addiction," Caporale said. She noted that some e-cigarettes contain more nicotine than what's on the label.
Not like Benign as Some Believe
Similarly, Karen M. Wilson, MD, MPH, pediatrician at Icahn School of Medicine at Mount Sinai, New York City, who was not involved in the study, told Medscape Medical News that "it has been this story that electronic cigarettes create this harmless" water vapor ", thus making them useful for adults who want to quit smoking.
But" what we really start to understand "is that in addition to nicotine, the aerosol contains other potentially toxic particles, she said.
According to Wilson, although it is unknown what the effects will be after 20 or 30 years, this study suggests that, as with smoking, "we are likely to see a increase in cardiovascular disease "from vaping.
It is important that" some of these vascular changes in the lungs or direct irritation from the toxins and particles in the aerosol [may be] precipitate "the recently seen cluster of cases of severity like lung disease in young people who had guns, Wilson said.
As recently reported, from July to August 8, there were 12 confirmed cases and 13 cases under examination by teenagers and young adults in Wisconsin who were admitted to hospitals for severe post-vaping lung problems.
Newer e-cigarette models, such as Juul (Juul Labs), which have nicotine salt, make it easier to inhale higher concentrations of nicotine, Wilson pointed out. "When [young people] recognizes that it is dangerous, they are already addicted."
It is important that the current study shows that "even without nicotine, [e-cigarettes are] is still harmful," she emphasized, adding that there is no need to inhale anything except air or, if necessary, medicines, such as albuterol for asthma.
Similarly, Deepak L. Bhatt, MD, MPH, a cardiologist at Brigham and Women's Hospital and professor at Harvard Medical School in Boston, Massachusetts, told Medscape Medical News, "Vaping is growing among young people at an alarming rate, and the widespread perception among them is that this is safe for health. " Bhatt was not involved in the study.
"However, this study shows that these aerosols negatively affect markers of endothelial function as assessed by MRI and adds to the growing literature that vaping is poor for cardiovascular disease.
" Unfortunately, the full clinical effect of vaping will not known for several years, "he noted.
Effect of aerosols on blood vessels
The e-liquid in e-cigarettes contains propylene glycol, glycerine, flavorings and various amounts of nicotine. On heating, the aerosol that forms formaldehyde and acetaldehyde (likely) carcinogens) and tiny metal particles (probably from the heating element).
When inhaled, the lung alveoli reach blood vessels and can cause systemic oxidative stress and inflammation, as reported in studies of e-cigarettes containing nicotine,
To investigate this in e-cigarettes without nicotine, Caporale and colleagues conducted an MRI study in 17 men and 14 women aged 18 to 35 years. The participants had never smoked or weapons. Their body mass index was 18 to 35 kg / m 2 and they had no apparent cardiovascular or neurovascular disease.
Under supervision, participants participated in a "vaping challenge" in which they inhaled for 3 seconds (without coughing or swallowing the vapor) 16 times, using a disposable cigarette (Eco-series; Epuffer) containing propylene glycol, glycerol and flavor , but no nicotine. A 3.7-volt battery operated the e-cigarettes.
Participants underwent MRI scan of the superficial femoral artery and vein, the superior sagittal sinus, and the aorta before and after the vaping challenge.
The researchers determined fluid-mediated femoral artery expansion and oxygen saturation in the femoral vein by narrowing the blood vessels in the upper leg using a cuff, and then releasing the cuff.
"The blood flow is completely disturbed for the femoral artery and vein for a few minutes, and then it is released, and then blood will flow through the artery and return to the heart through the veins," Wehrli explained.
The researchers also assessed the cerebrovascular reactivity of the sagittal sinus using a respiratory arrest, where participants held their breath for 30 seconds and breathed normally for 2 minutes three times.
MRI imaging was used to determine aortic pulse wave velocity.
A comparison of pre- and post-vaping M RI data following a single vaping challenge yielded the following results:
a 34% reduction in femoral artery mediated dilation and a 25.8% blood flow acceleration ( P <.001 for both), indicates endothelial dysfunction;
a 20% reduction in oxygen saturation of the femoral veins ( P <0.001), indicating microvascular impairment; and
a 3% increase in aortic pulse wave velocity ( P = 0.05), suggesting aortic stiffening.
There were no statistically significant differences in the cerebrovascular reactivity of the sagittal sinus ( P = .08).
"Although 31 is not a very large number [of participants]the effects we observed [were] were very statistically significant," Wehrli emphasized.
Related studies support current findings
It would be unethical to conduct this experiment using tobacco cigarettes in non-smokers, Wehrli noted.
However, the team has previously conducted a study showing similar adverse vascular effects in long-term cigarette smokers.
another recent study, demonstrated that nicotine-free e-cigarette vaping caused a transient increase in serum markers of inflammation (C-reactive protein) and oxidative stress, reaching the peak 1 to 2 hours after vaping and returning to baseline within 6 hours. These results support the findings in the present study.
The research was funded by the National Heart, Lung and Blood Institute. The authors have not provided any relevant financial conditions.
Radiology. Published online August 20, 2019.
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