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  2. Heart rate variability - Wikipedia

    en.wikipedia.org/wiki/Heart_rate_variability

    Heart rate variability visualized with R-R interval changes Electrocardiogram (ECG) recording of a canine heart that illustrates beat-to-beat variability in R–R interval (top) and heart rate (bottom). Heart rate variability (HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the ...

  3. MDCalc - Wikipedia

    en.wikipedia.org/wiki/MDCalc

    MDCalc is a free online medical reference for healthcare professionals that provides point-of-care clinical decision-support tools, including medical calculators, scoring systems, and algorithms. [1] MDCalc is also a mobile and web app. [ 2 ] The decision-support tools are based on published clinical research, [ 3 ] and MDCalc’s content is ...

  4. Heart rate - Wikipedia

    en.wikipedia.org/wiki/Heart_rate

    On the ECG, instantaneous heart rate is calculated using the R wave-to-R wave (RR) interval and multiplying/dividing in order to derive heart rate in heartbeats/min. Multiple methods exist: [citation needed] HR = 1000 · 60/(RR interval in milliseconds) HR = 60/(RR interval in seconds) HR = 300/number of "large" squares between successive R waves.

  5. Poincaré plot - Wikipedia

    en.wikipedia.org/wiki/Poincaré_plot

    An RR tachograph is a graph of the numerical value of the RR-interval versus time. In the context of RR tachography, a Poincaré plot is a graph of RR(n) on the x-axis versus RR(n + 1) (the succeeding RR interval) on the y-axis, i.e. one takes a sequence of intervals and plots each interval against the following interval. [3]

  6. Pan–Tompkins algorithm - Wikipedia

    en.wikipedia.org/wiki/Pan–Tompkins_algorithm

    The average RR is computed in two ways to consider both regular and irregular heart rhythm. In the first method RRaverage1 is computed as the mean of the last RR intervals. In the second method RRaverage2 is computed as the mean of the last RR intervals that fell between the limits specified as: = %

  7. QT interval - Wikipedia

    en.wikipedia.org/wiki/QT_interval

    The QT interval is a measurement made on an electrocardiogram used to assess some of the electrical properties of the heart.It is calculated as the time from the start of the Q wave to the end of the T wave, and approximates to the time taken from when the cardiac ventricles start to contract to when they finish relaxing.

  8. Heart rate turbulence - Wikipedia

    en.wikipedia.org/wiki/Heart_rate_turbulence

    To clarify, they listed the time from one heartbeat's R-wave to the next R-wave (called RR intervals) and synchronized these lists to the time of the PVC beat and averaged the values in the list. A plot of this averaged RR interval list (called a PVC tachogram) not only confirmed their observation that heart rate sped up for a few beats after a ...

  9. Aortic valve area calculation - Wikipedia

    en.wikipedia.org/wiki/Aortic_valve_area_calculation

    From these, it is easy to calculate the area (in cm 2) of the aortic valve by simply dividing the LV stroke volume (in cm 3) by the AV VTI (in cm) measured on the spectral Doppler display using continuous-wave Doppler. [citation needed] Stroke volume = 0.785(π/4) x Diameter 2 x VTI of LVOT Cross sectional area of LVOT = 0.785(π/4) x LVOT ...