Sections of a Holter ECG of a patient two weeks after
acute myocardial infarction. The patient survived without complications.
"Local tachogram": Subsequent to the PVC the RR intervals
shorten, and after a few beats a counterreaction is initiated. The RR intervals
gradually increase between the 6th and the 12th beat followed by an eventual
return of the system to its initial frequency.
Sections of a Holter ECG and local tachogram of a patient
two weeks after acute myocardial infarction. The patient died suddenly three
months later. HRT is almost entirely absent.
Calculation of Turbulence Onset
Calculation of Turbulence Slope
Quantification of HRT
(1) Turbulence Onset: percentage difference between the average
value of the first two normal intervals following the PVC and of
the last two normal intervals preceding the PVC. Initially, TO is
determined for each individual PVC, followed by the determination
of the average value of all individual measurements.
(2) Turbulence Slope: steepest slope of a linear regression line
through five consecutive measurement points in the averaged
tachogram. The Turbulence Slope calculations are based on the
averaged tachogram and expressed in ms per RR interval.