Download Chapter 6: HRV Assessment and Interpretation

Overview of HRV Measurement
using the emWave PC
Turn on the data-logging feature of the emWave PC
To set the
emWavePC
program to collect
RR interval data:
In the emWavePC
program, go to
Settings, Options,
User Interface tab.
Uncheck Enable
Simple Interface.
Click the OK
button.
1
Go to Settings,
Options, Data
Logging tab.
Check the Simple
RR Log item.
Click the Show
Folder button to
open a window
that shows the
folder that will
contain the RR
interval files. Click
the OK button.
The default path to
the data files is
C:\Documents and
Settings\All
Users\Application
Data\Quantum
Intech\emWave
but can vary
depending on the
type of program
installation that
was done.
The emWavePC program will now produce an RR interval file automatically for each
session until the options are reset.
2
Run a
session with
the
emWavePC
program to
create an
RR interval
file.
The data file
name is
constructed
from the
current user
name, date
and time.
3
Analyzing the data
Interbeat interval data file can be analyzed by a free HRV analysis program available
from: http://www.it.uku.fi/biosignal/winhrv.shtml
Email the program authors at [email protected]
to get the password for downloading the program. (It may take them a couple of days to
respond.)
The program will give you a report that you can print or you can export this data to an
Excel spreadsheet and keep adding your different subjects to it in order to run stats.
The minimum length for analysis is 5 minutes; so if you are including the 1 minute / 6
breaths breathing collections as part of your research- you will need to send those files
to IHM. See the instructions for that below.
Start the HRV
software. It will
ask for a data
file. Navigate in
the Get Data File
dialog box to:
C:\Documents
and Settings\All
Users\Applicatio
n Data\Quantum
Intech\emWave
(or the location
indicated by the
Show Folder
button) Select
the data file that
you want to
process. Click
the Open button.
4
The program
will produce
an HRV
analysis.
You can
change the
range of
values
selected for
analysis by
dragging the
vertical bars
in the data
display at
the top of
the screen.
5. Email the two saved files to Jackie Waterman at HeartMath
[email protected]
5
Within the body of the email, include the age and gender along with either the
name of the client, and/or their id code for each file you attach. You may also
want to include any heart medications if taking medical history is part of your
protocol as well as pertinent diagnosis (e.g. bypass surgery, diabetic)The files
that you will be sending are located in the folder described above when you were
turning on the logging feature. (C:\Documents and Settings\All Users\Application
Data\Quantum Intech\emWave) They will have “ .dat “ at the end. You can
change the name of the file as you would any other file name, but leave the dat
extension along with the date and time info. Since the 10 minute STAAR is
collected first and then the 1 minute breathing, the oldest file should be a little bit
larger in size. They are both very small files and will email very easily as
attachments. For questions, please call Jackie at 831-338-8769
6. HeartMath will return results to you via email.
Background Information on HRV Measurement and
Interpretation
6
Overview
Heart-rhythm analysis is more than a measurement of heart rate; it is a much
deeper measurement of the complex interactions between the brain, the heart
and multiple systems in the body. It’s important to understand that the heart
rhythm can be measured from two perspectives that offer different levels of
information about the client’s psychophysiological status.
The most common measurement of HRV involves quantifying the amount of HRV
over a given time period. Although the amount of HRV is clearly an important
factor to measure, the rhythms and patterns contained in the HRV are more
reflective of emotional states. Therefore, when considering HRV, it's possible to
assess 1) how much variability is occurring (the amplitude of the wave) and 2)
the pattern of the heart rhythm (coherent or incoherent).
Measuring the Overall Amount of HRV
The amount of HRV (amplitude) is related to age. Younger individuals have a
greater range in the natural beat-to-beat variation than older individuals.
Abnormally low HRV, relative to one’s age, is a strong and independent predictor
of future health problems, including all causes of mortality. In addition, low levels
of HRV are considered a psychophysiological marker of impaired emotional
regulation and psychological adjustment. Thus, HRV is an important indicator of
both physiological resiliency and behavioral flexibility, reflecting the individual’s
capacity to adapt effectively to stress and environmental demands. The amount
of HRV one has, relative to age, is therefore an indicator of overall vitality or
system depletion. Overall system depletion does not typically occur over short
time periods unless the patient has been exposed to an extreme trauma. Rather,
reductions in the amount of overall HRV, in the absence of a clinical disorder
such as diabetes, tend to occur over months and years, often because of the
cumulative effects of chronic depletion stemming from emotional stress.
7
If the goal of the HRV measurement is assessment, it is best to assess the
overall amount of HRV a client or patient has over a 24-hour period with an
ambulatory ECG recording device. However, if an individual has chronically low
HRV, a shorter 10-minute measurement can be done as a screening test. The
amount of HRV can vary considerably during different times of the day and night
because of a wide range of state-specific factors, including the current emotional
state, heart rate and mental workload. Therefore, if screening indicates a low
HRV, a 24-hour test should be performed before any medically relevant
conclusions are reached (e.g. assessment of risk for sudden cardiac death,
diabetic neuropathy and other patient-specific risks.)
Measuring the Patterns in the Heart Rhythm
While the amount of HRV can and often does covary with specific emotional
states, we have found that it is the pattern of the heart’s rhythm that is primarily
reflective of the emotional state. Furthermore, we have found that changes in the
heart-rhythm pattern are independent of heart rate; One can have a coherent or
incoherent pattern at high or low heart rates. Thus it is the rhythm, rather than the
rate, that is most directly related to emotional dynamics and physiological
synchronization.
8