Table 2.

List of abbreviations used in the algorithm description. The superscript ⁱ indicates the current beat, ⁱ⁺¹ the first next beat and ⁱ⁺² the second next beat.

AC = Closure of the aortic valve (fiducial point)
ACRdelay = Time position of AC with respect to the R peak (in ms)
AFPRdelay = Average FPRdelay estimated in the 5 beats preceding or following the current beat
AO = Opening of the aortic valve (fiducial point)
MC = Closure of the mitral valve (fiducial point)
MO = Opening of the mitral valve (fiducial point)
CFTP = Coarse FP Time Position: FP timing with a 5  ms precision (in ms)
D = D1 + D2
D1 = Distance (in amplitude) between IRP and the adjacent left minimum (in mg), see Fig. 5 panel c
D2 = Distance (in amplitude) between IRP and the adjacent right minimum (in mg), see Fig. 5 panel c
FP = Fiducial Point (either AC, AO, MC or MO)
FPRdelay = Time position of the generic FP with respect to the R peak (in ms)
HRFTP = HiRes FP Time Position: FP timing with 1  ms precision (in ms)
ICP = Isovolumic Contraction Point (anchor point used for detection of MC and AO)
|ICPd| = Absolute value of the ICP distance from the 0 g baseline (in mg)
ICP Rdelay = Time position of ICP with respect to the R peak (in ms)
ICP Rdelay ref = ICP Rdelay observed in the closest valid beat (the reference).
IRP = Isovolumic Relaxation Point (anchor point in S2 used for detection of AC and MO)
IRP Rdelay = Time position of IRP with respect to the R peak (in ms)
IRP Rdelay ref = IRP Rdelay observed in the closest valid beat among the last 20 beats (the reference).
RRI = RR Interval (in ms)
S1 = Peak in the SCG envelope corresponding to the first heart sound
S1si = 50 ms SCG segment starting after 25 ms from the R peak where ICP, MC and AO are searched for
S2 = Peak in the SCG envelope corresponding to the second heart sound
S2si = 60 ms SCG segment centered on Te where IRP, AC and MO are searched for
Te = End of T wave
Te Rdelay = Time position of Te with respect to the R peak (in ms)