Download Dynamics of Heart Rate Turbulence

Dynamics of Heart Rate Turbulence
Axel Bauer, Raphael Schneider, Petra Barthel, Marek Malik and Georg Schmidt
Deutsches Herzzentrum München & 1. Medizinische Klinik der Technischen Universität München, Germany
Medical School, St. George’s Hospital, London, United Kingdom
Compensatory
Pause
RR-interval [ms]
1000
-3 -2 -1
Turbulence Slope
Turbulence Onset
800
Heart Rate Turbulence
600
Coupling
Interval
0
5
10
Beat Number
15
Methods: This study was performed in 743 patients of the
placebo arm of the EMIAT trial. Of these, 151 patients
were excluded because of atrial fibrillation, no VPC during
the Holter recording or missing Holter recording. During a
median follow up of 21 months, 509 patients survived and
82 patients died. Holter recordings were obtained in the
second or third week after index infarction. VPCs were
included, if they featured ≥3 consecutive sinus intervals
before and ≥15 consecutive sinus intervals after the ectopic
beat, and if they were followed by a compensatory pause
(defined as coupling interval + post-extrasystolic pause = 2
normal-to-normal intervals ±10%).
Actual Heart Rate =
1
3
60.000
⋅ (RRI (−3) + RRI (−2) + RRI (−1) )
The impact of the heart rate heart-rate turbulence was
separately analyzed in surviving and non-surviving patients.
The VPCs were sorted according to the actual heart rate.
For each percentile of heart rate, an averaged tachogram
was calculated. In each tachogram, the HRT-parameters TO
and TS were derived according to the previously published
technology.
Results: In surviving patients, 75.391 VPCs met the
inclusion criteria. In non-surviving patients, this figure was
24.816.
In both, surviving and non-surviving patients, heart-rate
turbulence decreased with increasing heart rates. The
characteristics of the correlations were somewhat different
for both parameters. Turbulence Onset was highest at low
heart rates and gradually decreased at higher heart rates. At
a heart rate of 80 bpm (non-survivors) and 100 bpm
(survivors) TO almost abolished, whereas Turbulence Slope
decreased over the whole range of heart rates. The slopes of
the regression lines were generally higher in surviving
patients than in non-surviving patients (Table).
Conclusions: The impact of heart rate on HRT maybe
twofold. At high heart rates, the duration of the
postextrasystolic pause progressively shortens, so that the
drop in diastolic arterial pressure diminishes and the
hemodynamic trigger of heart-rate turbulence becomes
weaker. Moreover, the sympatho-vagal balance is shifted in
favor of a prevailing sympathetic tone, so that the
baroreflex sensitivity may be attenuated.
VPC of survivors
VPC of non-survivors
-2
-1
0
40
60
80
100
6
Turbulence Slope [ms/RRI]
For each VPC, the actual heart rate was calculated from the
last three normal intervals by the formula:
Turbulence Onset [%]
Introduction: Heart-Rate Turbulence (HRT) is the
physiological short-term oscillation of the heart rate after a
single ventricular premature complex (VPC)1.
HRT probably reflects baroreflex activity triggered by the
transient perturbation of arterial blood pressure after a
VPC2,3. Therefore, the heart rate directly preceding the VPC
should influence HRT.
Aim of this study is to analyze the impact of the heart rate
on HRT.
4
2
0
40
120
Survivors
TO
Actual Heart Rate
60
80
100
120
Heart Rate [bpm]
Heart Rate [bpm]
Non-Survivors
TS
r = 0.93 1) r = 0.85 2)
TO
TS
r = 0.65 3) r = 0.85 4)
1)
TO = 0.044 ⋅ HR − 4.535
3) TO
= 0.02 ⋅ HR − 2.134
2)
TS = −0.061 ⋅ HR + 8.281
4) TS
= −0.044 ⋅ HR + 5.176
all correlations p < 0.0001
Literature:
1)
Schmidt, G., et al., Heart-rate turbulence after ventricular premature beats
as a predictor of mortality after acute myocardial infarction
Lancet, 1999. 353(9162): p. 1390-6.
2)
Malik, M., D. Wichterle, and G. Schmidt, Heart-Rate Turbulence.
G Ital Cardiol, 1999. 29: p. 65-9.
3)
Mrowka, R., et al., Blunted arterial baroreflexes causes "pathological" heart
rate turbulence.
Am J Physiol Regulatory Integrative Comp Physiol, 2000. 279: p. 1171-5.