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Y. A. Abdulhameed et al.
differences in the neurogenic and NO-dependent endothelial intervals, with their
band powers being markedly increased in FM patients. No significant differences
were found during the same comparisons for normalized band power within the
NO-independent endothelial interval.
26.4.2.2 Spectral Power in Instantaneous Heart Frequency
Fluctuations
The IHF analysis results are summarised in Fig. 26.2 (lower panel). Fluctuations
in the IHF signal (derived from the ECG) in the frequency intervals associated with
myogenic (FI-III), nitric oxide-dependent endothelial activity (FI-V) and nitric oxideindependent endothelial activity (FI-VI) (p = 0.000006, p = 0.003 and p = 0.003),
respectively decreased significantly in febrile malaria compared to NM (Fig. 26.2),
although the spectral power around 0.021 Hz tended to be lower for FM (Fig. 26.2a).
But in the FI-II frequency interval associated with respiratory activity, FM exhibited
a significantly higher normalised spectral power (p = 0.0001) compared to NM
(Fig. 26.2), a similar finding being evident in the IHF absolute power (although not
shown here). In a similar manner, the power of the IHF oscillations of the NFM group
was significantly higher (p = 0.004) within the FI-II respiratory frequency interval
when compared to NM, but markedly lower in the frequency intervals associated
with myogenic (FI-III), neurogenic (FI-IV) and NO-related endothelial activity (FIV) (p = 0.017 and p = 0.018 respectively). No significant difference was observed
in any of the frequency intervals of IHF normalised spectral power in the FM and
NFM comparison.
26.4.2.3 Coherence Between Fluctuations in IHF in Left and Right
Ankles
Figure 26.3 presents the averaged coherence between IHF1 and IHF2, showing that
there is significant coherence in the oscillations reflecting respiratory (II), myogenic
(III), neurogenic (IV) and NO-independent endothelial activity (VI), but most pronounced in the NM group, whilst within the high frequencies (> 0.1 Hz) the coherence is diminished in NFM and extremely small in FM (Fig. 26.3a). The coherence in
frequency intervals II, III, IV, V and VI is significantly smaller in FM (p = 0.000000, p
= 0.00000, p = 0.0000000 , p = 0.000000 and p = 0.00000004, respectively) and NFM
(p = 0.0008, p = 0.0005, p = 0.0038, p = 0.0021 and p = 0.0068, respectively) when
compared to the NM group. In the FM–NFM comparison, however, the coherence
did not differ significantly in any frequency interval.
Y. A. Abdulhameed et al.
differences in the neurogenic and NO-dependent endothelial intervals, with their
band powers being markedly increased in FM patients. No significant differences
were found during the same comparisons for normalized band power within the
NO-independent endothelial interval.
26.4.2.2 Spectral Power in Instantaneous Heart Frequency
Fluctuations
The IHF analysis results are summarised in Fig. 26.2 (lower panel). Fluctuations
in the IHF signal (derived from the ECG) in the frequency intervals associated with
myogenic (FI-III), nitric oxide-dependent endothelial activity (FI-V) and nitric oxideindependent endothelial activity (FI-VI) (p = 0.000006, p = 0.003 and p = 0.003),
respectively decreased significantly in febrile malaria compared to NM (Fig. 26.2),
although the spectral power around 0.021 Hz tended to be lower for FM (Fig. 26.2a).
But in the FI-II frequency interval associated with respiratory activity, FM exhibited
a significantly higher normalised spectral power (p = 0.0001) compared to NM
(Fig. 26.2), a similar finding being evident in the IHF absolute power (although not
shown here). In a similar manner, the power of the IHF oscillations of the NFM group
was significantly higher (p = 0.004) within the FI-II respiratory frequency interval
when compared to NM, but markedly lower in the frequency intervals associated
with myogenic (FI-III), neurogenic (FI-IV) and NO-related endothelial activity (FIV) (p = 0.017 and p = 0.018 respectively). No significant difference was observed
in any of the frequency intervals of IHF normalised spectral power in the FM and
NFM comparison.
26.4.2.3 Coherence Between Fluctuations in IHF in Left and Right
Ankles
Figure 26.3 presents the averaged coherence between IHF1 and IHF2, showing that
there is significant coherence in the oscillations reflecting respiratory (II), myogenic
(III), neurogenic (IV) and NO-independent endothelial activity (VI), but most pronounced in the NM group, whilst within the high frequencies (> 0.1 Hz) the coherence is diminished in NFM and extremely small in FM (Fig. 26.3a). The coherence in
frequency intervals II, III, IV, V and VI is significantly smaller in FM (p = 0.000000, p
= 0.00000, p = 0.0000000 , p = 0.000000 and p = 0.00000004, respectively) and NFM
(p = 0.0008, p = 0.0005, p = 0.0038, p = 0.0021 and p = 0.0068, respectively) when
compared to the NM group. In the FM–NFM comparison, however, the coherence
did not differ significantly in any frequency interval.