New Insights From MRI and Cell Biology Into the Acute Vascular-Metabolic Implications of Electronic Cigarette Vaping

Figures

• 

  FIGURE 1. Cascade of events following e-cigarette inhalation, initiating vascular inflammation and dysfunction. Ultra-fine particles (UFP) and free radicals, deposited on the respiratory tract are taken up by endothelial cells. This process drives endothelial activation that triggers inflammation signaling, eventually leading to vascular dysfunction (original figure).

• 

  FIGURE 2. Multi-vascular MRI protocol. The 50-min MRI protocol included a measure of peripheral vascular reactivity (PVR) to cuff-induced ischemia, followed by cerebrovascular reactivity (CVR) and aortic pulse wave velocity (PWV) quantification. PVR was assessed in the femoral vessels via multiple techniques. To stimulate reactive hyperemia the cuff was placed around the upper thigh and inflated for 5 min. CVR to hypercapnia in the form of volitional apnea was measured in the superior sagittal sinus (artwork modified from Caporale et al., 2019; Supplementary Figure B1, with permission from RSNA publisher).

• 

  FIGURE 3. Arterial velocimetry at baseline and hyperemia. (A) Blood flow velocity in the superficial femoral artery, during baseline and post-cuff occlusion (reactive hyperemia). Systolic, retrograde, and baseline velocities are indicated (Vs, Vr, and Vb, respectively). Post-ischemia, hyperemia is evaluated in terms of hyperemic index (HI) as the slope of the initial part of the velocity-time curve, peak average velocity (VP), and duration of hyperemia, referred to as time of forward flow (TFF). (B) Axial MR image of the thigh perpendicular to the femoral artery. (C) Pre- vs. post-electronic cigarette (e-cig) vaping differences for two parameters, in non-smokers, after a single episode of non-nicotinized e-cig vaping. The same MRI protocol was executed before and after e-cig use (modified from Caporale et al., 2019; Figures 2, 5, with permission from RSNA publisher).

• 

  FIGURE 4. Venous oximetry and flow-mediated dilation. (A) Post-cuff release venous oxygen saturation (SvO2) interleaved with vessel wall imaging to derive femoral artery flow-mediated dilation (FMD) measurement at 60, 90, and 120 s following cuff deflation, with respect to the lumen at rest (B). (B–D) Pre vs. post-e-cig vaping differences for the extracted metrics: (B,D) luminal FMD (FMDL), (C) pre-cuff occlusion baseline SvO2 [SvO2(b)], washout time (TW), and overshoot (A,B are original, produced from data already published in Caporale et al., 2019; (C,D) are modified from Caporale et al., 2019; Figure 5, with permission from RSNA publisher).