Download Heart rate variability by Poincaré plot and spectral analysis in young

Heart rate variability by Poincaré plot and spectral analysis in young healthy subjects and
patients with type 1 diabetes
Przemysław Guzik, MD, PhD, Bartosz Bychowiec, MD, Jarosław Piskorski*, PhD,
Adam Węgrzynowski**, MD, Tomasz Krauze, MSc, Raphael Schneider*** Ing.,
Piotr Liszkowski**, MD, Andrzej Wykrętowicz, MD, PhD,
Bogna Wierusz-Wysocka***, MD, PhD and Henryk Wysocki, MD, PhD
Department of Cardiology-Intensive Therapy, University of Medical Sciences in Poznań,
Przybyszewskiego 49, 60-355 Poznań, Poland;
*Institute of Physics, University of Zielona Góra, Zielona Góra, Poland;
**Department of Diabetology, University of Medical Sciences in Poznań, Poland
***Klinikum rechts der Isar, TUM, Munich, Germany;
e-mail: [email protected]
Abstract: An abnormal autonomic modulation of the
heart rate is common in young patients with type 1
diabetes (IDDM). Both spectral heart rate variability
(HRV) and the Poincaré plot (PP) analysis of RR
intervals has been employed in the evaluation of
autonomic control of the heart rate. However, spectral
HRV and not the PP HRV has been used in IDDM
patients. We aimed to describe HRV with the use of
spectral and PP analysis in young IDDM patients and
healthy subjects. Resting 5 minutes ECG was recorded
in 70 healthy young volunteers (19 – 28 years old, 32
female) and 39 young IDDM patients (18-34 years, 17
female). Compared with healthy volunteers, IDDM
patients presented significantly reduced values of SD1
(p<0.0001), SD2 (p<0.0001), the area of imaginary
ellipse of PP (p<0.0001), HF (p=0.0116) and LF/HF
(p=0.0013) and not quite significantly decreased ratio
of SD2/SD1 (p=0.0765). The values of TP and LF did
not differ significantly between IDDM patients and
healthy volunteers. In conclusion, similarly to the
spectral approach to HRV, the Poincaré plot analysis
reveals that patients with IDDM have reduced HRV,
which may be secondary to some autonomic
dysfunction. Both spectral HRV and PP analysis
showed that short term HRV is abnormal in IDDM
patients. Conversely, the PP analysis but not spectral
HRV demonstrated that the total and long-term HRV is
also impaired in IDDM patients.
INTRODUCTION
Poor glycemic control plays an important role in
the development and progression of autonomic
dysfunction in patients with type 1 diabetes
mellitus (IDDM).1,2 It has been demonstrated on
several occasions that reduced cardiovascular
autonomic function may be measured by heart rate
variability (HRV).3-7
The Poincaré plot (PP) analysis of RR
intervals (RRI) is a nonlinear HRV method and it
has been shown to reflect autonomic control of the
heart rate.8-21 To the best of our knowledge it
seems that PP analysis has not been used as a
measure of HRV in IDDM patients.
In this study we used both spectral and
PP-derived analysis of HRV to evaluate the
autonomic control of the heart rate in young
IDDM patients and healthy people.
SUBJECTS & METHODS
Patients with type 1 diabetes.
Thirty nine young IDDM patients (18-34 years, 17
female) with at least 5 years history of the disease
and the presence of sinus rhythm were recruited in
the study.
Healthy subjects
Seventy young healthy volunteers (19 – 28 years
old, 32 female) agreed to participate in the study.
Protocol & methods.
The study was performed in a warm and quiet
room with all individuals resting for 15 minutes in
supine position and breathing spontaneously.
Afterward, 3-channel chest ECG was recorded by
an A/D converter with sampling frequency of
1600 Hz (Porti 5, TMSI, The Netherlands) for 5
minutes. The recorded signals were evaluated with
special software - RASCHlab from the libRASCH
project (v. 0.6.1; www.librasch.org, Germany).22
After an automatic evaluation of ECG, the visual
inspection and all necessary corrections were
done. The values of RRIs were retrieved from the
stored recordings and used in further analysis.
Measurement of heart rate and its variability
64
RESULTS
Compared with healthy volunteers, IDDM patients
presented significantly reduced values of SD1
(60.0+/-52.0 vs. 25.4+/-13.7 ms; p<0.0001), SD2
(115.0+/-54.0 vs. 61.5+/-24.9 ms; p<0.0001), S
(29276+/-46524 vs. 5751+/-5200 ms2; p<0.0001),
HF (447.6+/-384.5 vs. 268.4+/-273.7 ms2;
p=0.0116) and LF/HF (2.1+/-1.2 vs. 3.3+/-2.7;
p=0.0013) whereas the ratio SD2/SD1 was not
quite significantly decreased (2.4+/-0.8 vs. 2.7+/0.9; p=0.0765). The values of TP (3088+/-4484 vs.
1908+/-1584 ms2; n.s.) and LF (837.5+/-803.5 vs.
631.7+/-571.5 ms2; n.s.) did not differ significantly
between IDDM patients and healthy volunteers.
All results are shown on Figures 2-5.
10000
80000
8000
n.s.
p<0.0001
60000
S [m s2]
T P [m s 2 ]
Heart rate, expressed in terms of RRI, and HRV
were measured in all recordings. For HRV
analysis 2 approaches were used:
- frequency domain HRV with assessment of
total power (TP), low frequency power (LF)
and high frequency power (HF), and LF to
HF ratio (LF/HF) according to published
references;7
- PP analysis with the use of home-made
scripts written in Matlab (The MathWorks
Inc,
USA)
according
to
published
references.8,9
There are 2 standard descriptors of PP (see Fig. 1
below), namely SD2 (measuring the dispersion of
points along the line of identity) and SD1
(assessing the dispersion of points across the
identity line).8,9 SD1 is a measure of short term
HRV whereas SD2 a measure of long and short
term HRV.8-11
6000
4000
40000
20000
2000
0
0
Healthy
IDDM
Healthy
IDDM
Figure 2. Total HRV by spectral (left part) and
Poincaré plot (right part) analyses in healthy people
and IDDM patients.
900
125
p=0.0116
450
300
75
50
25
150
0
0
Healthy
IDDM
Healthy
IDDM
Figure 3. Short-term HRV by spectral (left part) and
Poincaré plot (right part) analyses in healthy people
and IDDM patients.
2000
200
n.s.
1500
p<0.0001
150
S D 2 [m s]
LF [m s 2 ]
Additionally, we have combined SD1 and SD2 to
form two additional descriptors of PPs:
- S corresponding to the area of the imaginary
ellipse on the Poincaré plot and is expressed
by the formula S= π x SD1 x SD2;
- the ratio of SD2 to SD1 (SD2/SD1) by
analogy to LF/HF from spectral HRV
analysis.
We have reasons to believe that S illustrates the
total HRV and SD2/SD1 describes sympathovagal
balance.12
Statistical analysis
All continuous data were presented as means +/standard deviations (SD). Student t-test was
applied in statistical comparison of HRV
parameters between IDDM patients and healthy
subjects. Only p < 0.05 was considered
statistically significant. All graphs and analyses
were performed in Prism 4.02 for Windows
(GraphPad, USA).
p<0.0001
100
600
S D 1 [m s]
Figure 1. A sample of Poincaré plot with its descriptors
H F [m s 2 ]
750
1000
500
100
50
0
0
Healthy
IDDM
Healthy
IDDM
Figure 4. Short-term and long-term HRV by spectral
(left part) and Poincaré plot (right part) analyses in
healthy people and IDDM patients.
65
7
6
4
p=0.0013
3
S D 2/S D 1
5
LF /H F
p=0.0765
4
3
2
2
1
1
0
0
Healthy
IDDM
Healthy
IDDM
Figure 5. Sympathetic-parasympathetic balance by
spectral (left part) and Poincaré plot (right part)
analyses in healthy people and IDDM patients.
DISCUSSION
In this study we have found that young IDDM
patients, compared to healthy people, have
reduced HRV. This is a known phenomenon but
the new message is that the reduced HRV in
IDDM patients can also be found with the use of
PP analysis. Moreover, it appears that PP analysis
was more sensitive than spectral HRV to present
attenuated autonomic modulation of the heart rate
in diabetic patients.
Diabetic patients are at risk of the
premature atherosclerosis leading to increased
cardiovascular morbidity. The ischemic heart
disease with acute coronary syndromes, heart
failure, diabetic cardiomyopathy, myocardial
infarction, various arrhythmias and sudden cardiac
death are more common and happen earlier than in
non-diabetic people. Additionally, abnormal
glucose metabolism with insulin deficiency,
chronic inflammation and endothelial dysfunction
lead to repetitive tissue ischemia and may produce
autonomic neuropathy.1,2,3,6 Therefore, there are
many reasons for HRV reduction in the course of
diabetes. It may be secondary to the impaired
function of cardiovascular system, to the presence
of diabetic autonomic neuropathy and to the
occurrence of both complications of the disease.
In fact, the reduced HRV in IDDM
individuals was better reflected with PP analysis
than with spectral method in our study. The
spectral HRV showed that only HF presenting
short-term RRI variability was significantly
decreased in diabetics. As a results, the balance
between sympathetic and parasympathetic
influences on the heart rate was increased in
IDDM patients compared with healthy persons. As
it was shown, there was no significant difference
in TP (total HRV) and LF (short- and long-term
HRV) between IDDM and healthy subjects.
Conversely, PP analysis of HRV showed that S,
being a measure of total HRV (and also of short-
term HRV), and SD2, expressing both short- and
long term HRV, are diminished in IDDM patients.
Similarly, SD1 reflecting short-term HRV was
significantly reduced in the diabetic patients as
well. The sympathetic-parasympathetic balance
described by PP analysis (SD2/SD1) was also
increased in diabetic individuals although not quite
significantly (p=0.0765).
Quite a lot of studies have proven that the
PP analysis of HRV is a reliable tool for
describing
autonomic
modulation
of
cardiovascular system. These studies have been
performed both in physiological and in clinical
settings.8-21 Nevertheless, it seems that it is the first
time that the Poincaré plot analysis has been used
in young people with type 1 diabetes to describe
autonomic control of the hear rate. The diabetic
neuropathy is the most probable but not the sole
cause of the observed HRV reduction in IDDM
patients. Additionally, the prospect of using the PP
analysis of HRV as a tool for the diagnosis of
diabetic neuropathy is very promising, but we
have not investigated this possibility, as our
objectives in the present study have been different.
This problem calls for more research and shall be
addressed in future studies.
CONCLUSION.
Both the Poincaré plot analysis and the spectral
method reveal that patients with IDDM have
reduced HRV. It looks like not only the spectral
HRV but the Poincaré plot analysis of RRI is also
able to show impaired autonomic control of the
heart rate in young IDDM patients.
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