Turbulence Onset (TO) is the
percentage difference between the heart rate immediately
following PVC and the heart rate immediately preceding PVC. It
is calculated using the equation
TO = ((RR1 + RR2)  (RR2 + RR1)) / (RR2 + RR1) * 100
with RR2 and RR1 being the first two normal intervals preceding
the PVC and RR1 and RR2 the first two normal intervals following
the PVC. Initially, TO is determined foreach individual PVC,
followed by the determination of the average value of all
individual measurements. Positive values for Turbulence Onset
indicate deceleration, negative values indicate acceleration of
the sinus rhythm.
The Turbulence Slope (TS)
corresponds to the steepest slope of the linear regression line
for each sequence of five consecutive normal intervals in the
local tachogram. The Turbulence Slope calculations are based on
the averaged tachogram and expressed in ms per RR interval.
