Variability of cardioinhibition in vasovagal syncope: differences between subgroups during cardioinhibition and beyond

Figures

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  Fig. 1. Definition of cardioinhibition. Two examples of definitions of cardioinhibition (CI) and asystole in two different subjects are shown. For all subjects, duration (D1) CI was defined as time from the start of the decrease in heart rate (HR) until minimum HR and magnitude CI (M1), namely: (HR at the start of HR decrease) — (the minimum HR ([M1]). In subjects with asystole, we defined the magnitude and duration of CI in a second way, namely as ‘duration2’ (D2), being from the start of HR decrease until the start of a HR pause ≥ 3 s, and ‘magnitude2’ (M2), namely: (HR at the start of the HR decrease) — (HR at the start of a HR pause ≥ 3 s)

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  Fig. 2. Hemodynamic parameters of 149 subjects with tilt-induced vasovagal syncope with marked, minimal and intermediate cardioinhibition, respectively. Subgroups were based on tertiles of the magnitude of cardioinhibition (CI). For each variable, the left panel represents the period around tilting in seconds, with negative timepoints reflecting the supine position. The right panels show the period around the start of CI, with the timepoint zero being the start of CI. The blue lines represent subjects with marked CI, the green lines are the subjects with intermediate CI and the red lines are subjects with minimal CI. The thin lines show the number of measurements for each point in time, as a percentage (with 100% at the top of the right axis). BP Blood pressure, HR heart rate, SV stroke volume, TPR total peripheral resistance

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  Fig. 3. Relation between age and supine heart rate (HR). The relation between supine HR before tilt-up is shown as a function of age. The black line shows the line of best fit used to calculate residuals. The relation was significant (p = 0.0056) albeit with limited explained variance (R2 = 0.05). The three subgroups of cardioinhibition (CI) severity are indicated. Note that the age ranges of the groups overlap, and that supine HR was highest for those with marked CI (red markers)