Post on 30-Dec-2015
Heart Rate Variability
in the Evaluation of Functional Status
Giedrius Varoneckas
Institute Psychophysiology and RehabilitationVyduno Str. 4, Palanga, Lithuania
e-mail: giedvar@ktl.mii.lt
Background
• Autonomic heart rate (HR) control, measured by means of
HR variability, might be seen as characteristic of
cardiovascular function, responsible for energetic supply of
any activities, physical, mental, or emotional
• There is generally agreed, that all activities followed by
increased sympathetic influence involves an increase of HR
frequency and a decrease of HR variability (HRV)
• Such model is appropriate for the main population, although
not for all: an exception might be well-trained sportsmen
with high quality achievements
Hypothesis
• HR frequency and HRV might be used for evaluation of quality
of work of operators mental or physical work loads
• HR frequency and HRV responses are not uniform for all
subjects
• The level of HR and HRV responses and direction of HRV
changes are dependent on their baseline level related to the
subject’s functional status
Autonomic HR control goes through three main mechanisms
• balance between of sympathetic-parasympathetic
branches of autonomic nervous system
(HR frequency and oscillatory structure)
• tonic control (HR variability)
• reflex control (mainly baroreflex)
Methods
• HR response - to active orthostatic test (AOT)
- to exercise (bicycle ergometry - BE)
• HR analysis using Poincare plot of RR intervals, collected
during complex of tests (sleep, wakefulness, AOT, and BE),
as a measure of overall ability to adapt to environmental
changes: internal or external
Power spectrum of RR interval sequence
(Fast Fourier analysis or autoregression analysis)
• HR variability at rest in stationary situation
Three main frequency components were measured: very low frequency component (VLFC), low frequency component (LFC),
high frequency component (HFC)
in absolute (ms) and relative (percent) values for evaluation of autonomic humoral,sympathetic-parasympathetic and parasympathetic control, correspondingly.
HR analysis using power spectrum
Heart rate analysis during active orthostatic test
RRRRBB, s = RR, s - RR, s = RR, s - RRBB, s, s
Maximal HR response to active orthostatic test (AOT)Maximal HR response to active orthostatic test (AOT)
Supine Standing-up Up-right
RR, ms
RR
RRB
RRB
%100,
,,%
sRR
sRRRR B
B
HR response to standard physical load
Heart rate analysis using Poincare plot
RR r
RRmin RRmax
RRrt
P, square of the plot, representing
overall HR variability
RRr, difference on plot diagonal between minimal (RRmin) and
maximal (RRmax) RR values
RRt, maximal HR variability, or tonic
control level, as maximal width-
difference between of two points at
parallel tangential lines determining
plot
RRmin, maximal HR frequency
RRmax, HR frequency at its minimal
level
Baseline level of autonomic control at rest (in supine) makes possible to evaluate
• balance between of P/S activation
• tonic control level, depending of P/S interaction
• reflex control level might be drawn from HR maximal response to AOT
Patterns of time and frequency domain HR characteristics
Rhythmogram patterns during quiet supine
Well-trained sportsman
Trainedsportsman
Sportsman
Non-trained healthy subject
HR and respiration patterns according prevalence of vagal control
maximal influence
high input
normal vagal control
Range of the HRV patterns of healthy Ss and the differences of
HR responses to deep breathing
enables to suspect
different HR responses to AOT, exercise, other activities,
involving changes of interplay between of P/S control
Rhythmogram patterns during quiet supine
Well-trained sportsman
Trainedsportsman
Sportsman
Non-trained healthy subject
• strongly reduced HRV pattern - V ; S 0• slightly increased HFC – V ; S inspiration• maximal domination of HFC with dispersed periodicity - V ; S • lowering again HRV with dominating HFC of strong periodicity – V ; S
Patterns of HR periodical structure in healthy subject:
• strongly reduced HRV pattern - V ; S 0
• slightly increased HFC – V ; S inspiration
• maximal domination of HFC with dispersed periodicity - V ; S
• lowering again HRV with dominating HFC
of strong periodicity – V ; S
Patterns of HR responses to active orthostatic test
Well-trained sportsman
Trained sportsman
Sportsman
Non-trained healthy subject
Patterns of HR responses to standard physical load
Well-trained sportsman
Trained sportsman
Sportsman
Non-trained healthy subject
Correlation of HR and respiratory arrhythmia to maximal oxygen consumption in well-trained sportsmen
Oxygen consumption and HR parameters in relation to HR variability and fitness level
Vo2, maximal oxygen consumption
RR1, RR interval in supine
RR2, RR interval during standing
RRB, maximal HR response to AOT
RRW1, HR during 1st load of PWC170 test
RRW2, HR during 2nd load of PWC170 test
HR parameters at morning-time, day-time just after training, and evening-time in sportsmen with prevailing aerobic or anaerobic processes
0
0.5
1
1.5
0
0.02
0.04
0.06
0
0.2
0.4
0.6RR, s
RR, s
RRB, s
0
0.05
0.1
0.15
0.2RA, s
Morning Day (after Eveningtraining)
Morning Day (after Eveningtraining)
HR patterns during AOT of the same sportsman at excellent state and overtraining
t, s
Concluding the presented results
• HRV might be very useful for evaluation of physical training
process, however
• the range and a direction of HR and its variability are
dependent on functional status (e.g. fitness) of particular
person and could be evaluated in relation to its baseline level
Sleep, being non-uniform state, due to shifts of sleep stages,
followed by the changes in autonomic HR control, might be
seen as a specific testing condition of the latter without an use
of work load
Non-REM sleep is characterized by an increase of
parasympathetic control and a slight decrease of sympathetic
one, while REM sleep is followed by withdrawal of
parasympathetic and an increase of sympathetic one
Looking from the point of presented classification of HR
variability pattern at wakefulness might be expected similar
dependence of a responses to shifts of sleep stages on initial
HR frequency and HR variability before sleep
RR interval, HR variability, and respiratory arrhythmia as functions of sleep stages in trained sportsmen and non-trained healthy subjects
0,04
0,08
0,12
Non-trained healthysubjects
Trained sportsmen
0.75
0.95
1.15
1.35
0,04
0,08
0,12RR, s RA, s
W 1 2 3 4 REM W 1 2 3 4 REM W 1 2 3 4 REM
RR, s
Poincare plots and power spectra of all-night HR recording
Sportsman Healthy subject CAD patient
Absolute (ms2) & relative characteristics (%) of power spectra of all-night HR recording
0
1000
2000
3000
4000
5000
6000
ULFC VLFC LFC HFC
S(f), ms2
0
10
20
30
40
50
ULFC VLFC LFC HFC
S(f),%
Sportsmen
Normals
CAD pts
50
70
90
110
3
5
7
Heart rate, stroke volume, and cardiac output as a functions of sleep stages
1
1
1RR, s SV, ml CO, l/min
90
100
110
120
70
90
110
130
70
90
110
130
W 1 2 3 4 REM
RR, % SV, % CO, %
W 1 2 3 4 REM W 1 2 3 4 REM
Healthy Ss CAD Pts
An example of HR power spectra during individual sleep stages in a healthy Ss
Sveikieji
0
25
50
75
100
Tipinës
0
25
50
75
100
Redukuotosios
0
25
50
75
100
B LM1 LM2 LM3 LM4 GM
NLLDK, % NLDK, % NADK, %
Changes of HR power spectrum components impact during shifts of sleep stages
Healthy Ss
CAD pts - typical
CAD pts - reduced
W Stage 1 Stage 2 Stage 3 Stage 4 REM
VLFC, % LFC, % HFC, %
The restorative function of sleep towards the cardiovascular system in trained sportsmen and non-trained healthy Ss
RR, ms
0,8
0,9
1
1,1
1,2
1,3
W 1 2 3 4
SV ml
40
80
120
W 1 2 3 4
CO, l/min
3
4
5
6
7
W 1 2 3 4
RR, ms
0,8
0,9
1
1,1
1,2
W 1 2 3 4Sleep cycles
I II III IV REMSleep stages:
SV, ml
30
70
110
W 1 2 3 4
Sleep cycles
CO, l/min.
2
3
4
5
6
7
W 1 2 3 4
Sleep cycles
RRB
20
30
40
50
RRB
20
30
40
50
Day Evening Morning
TPR
800
1200
1600
2000
2400
TPR
800
1400
2000
2600
Tra
ined
sp
ort
smen
Hea
lth
y S
s
The restorative function of sleep towards the cardiovascular system in healthy SS and CAD pts
RR, ms
0,8
0,9
1
1,1
1,2
1,3
W 1 2 3 4
SV, ml
40
80
120
W 1 2 3 4
CO, l/min
3
4
5
6
7
W 1 2 3 4
RR, ms
0,8
0,9
1
1,1
1,2
W 1 2 3 4Sleep cycles
I II III IV REMSleep stages:
SV, ml
40
80
120
W 1 2 3 4
Sleep cycles
CO, l/min.
3
5
7
W 1 2 3 4
Sleep cycles
RRB
20
30
40
50
RRB
20
30
40
50
Day-time Evening Morning
TPR
800
1200
1600
2000
TPR
800
1400
2000
2600
3200
CA
D p
tsH
ealt
hy
Ss
HR variability during different testing conditions in healthy subject and CAD pts
Sleep AOT evening-time AOT morning-time AOT day-time + Exercise test
CA
D p
tsH
ealt
hy
sub
jec
ts
HR variability in well-trained sportsman and non-trained subject
Sleep AOT evening-time
AOT morning-time
well-trained sportsman
non-trained subject
HR variability in CAD patient with and without HR restoration
with HR
restoration
inability to restore
Sleep AOT evening-time
AOT morning-time
Total sleep time
0
100
200
300
400
TST0
100
200
300
400
TST
min min
Healthy Subjects Pts with HR restoration
CAD Patients Pts showing Inability to restore
*
0
50
100
150
200
WASO Stage 1 Stage 2 Stage 3 Stage 4 REM
min
*
*
Restoration of HR control Inability to restore HR
*
Sleep structure in CAD patients with
* p<.05
Sleep structure in subjects distributed according to the HR reflex control changes during sleep
1 group 2 group 3 group
TST, min 326.1 319.5 310.5*1
Sleep Efficiency, % 87.8 85.9*1 84.1*1
REM latency, min 95.2 94.5 90.1
WASO, % 12.2 14.1*1 15.9*1
BM, % 2.6 2.7 2.9
Stage 1, % 8.8 9.7 10.6*1
Stage 2, % 52.1 53.3 53.5
Stages 3, % 8.6 6.8*1 5.6*1,2
Stages 4, % 2.6 1.2*1,2 .94*1
REM Sleep, % 13.1 12.2 10.6*1,2
Concluding the last session
restoration of both P and S control of HR, as well as
hemodynamics was dependent on a level of autonomic
HR control, e.g. on the subjects functional status at
baseline level
Conclusions
• Autonomic HR control measured by means of HR variability at baseline level is dependent on the subject’s functional status
• The responses of functional testing (physical, mental, or sleep) depends on the baseline level of autonomic control, i.e. HR variability pattern
• Both of them, baseline autonomic control and its modifications during individual testing conditions might, be used for training or work (physical or mental) process control
• This is true for responses to physical work load, reflex testing, or shifts of sleep stages, as well as to ability to recover cardiovascular system during sleep