Abstract

Nicotine-free e-cigarette aerosol inhalation in young, healthy nonsmokers resulted in transient impairment of vascular reactivity and endothelial function by using quantitative MRI metrics across multiple vascular beds.

Background

Previous studies showed that nicotinized electronic cigarettes (hereafter, e-cigarettes) elicit systemic oxidative stress and inflammation. However, the effect of the aerosol alone on endothelial function is not fully understood.

Purpose

To quantify surrogate markers of endothelial function in nonsmokers after inhalation of aerosol from nicotine-free e-cigarettes.

Materials and Methods

In this prospective study (from May to September 2018), nonsmokers underwent 3.0-T MRI before and after inhaling nicotine-free e-cigarette aerosol. Peripheral vascular reactivity to cuff-induced ischemia was quantified by temporally resolving blood flow velocity and oxygenation (SvO 2 ) in superficial femoral artery and vein, respectively, along with artery luminal flow-mediated dilation. Precuff occlusion, resistivity index, baseline blood flow velocity, and SvO 2 were evaluated. During reactive hyperemia, blood flow velocity yielded peak velocity, time to peak, and acceleration rate (hyperemic index); SvO 2 yielded washout time of oxygen-depleted blood, rate of resaturation, and maximum SvO 2 increase (overshoot). Cerebrovascular reactivity was assessed in the superior sagittal sinus, evaluating the breath-hold index. Central arterial stiffness was measured via aortic pulse wave velocity. Differences before versus after e-cigarette vaping were tested with Hotelling T2 test.

Results

Thirty-one healthy never-smokers (mean age, 24.3 years ± 4.3; 14 women) were evaluated. After e-cigarette vaping, resistivity index was higher (0.03 of 1.30 [2.3%]; P < .05), luminal flow-mediated dilation severely blunted (−3.2% of 9.4% [−34%]; P < .001), along with reduced peak velocity (−9.9 of 56.6 cm/sec [−17.5%]; P < .001), hyperemic index (−3.9 of 15.1 cm/sec2 [−25.8%]; P < .001), and delayed time to peak (2.1 of 7.1 sec [29.6%]; P = .005); baseline SvO 2 was lower (−13 of 65 %HbO 2 [−20%]; P < .001) and overshoot higher (10 of 19 %HbO 2 [52.6%]; P < .001); and aortic pulse wave velocity marginally increased (0.19 of 6.05 m/sec [3%]; P = .05). Remaining parameters did not change after aerosol inhalation.

Conclusion

Inhaling nicotine-free electronic cigarette aerosol transiently impacted endothelial function in healthy nonsmokers. Further studies are needed to address the potentially adverse long-term effects on vascular health.

© RSNA, 2019

Online supplemental material is available for this article.