What
is Heart Rate Variability?
Heart
rate variability studies examine alterations in the interval between heart
beats. Several physiological variables can affect the normal rhythm of the
heart and the interaction between the sympathetic and parasympathetic nervous
systems.
Heart
rate fluctuates based on a variety of conditions and can indicate the presence
of disease or forewarn impending cardiac diseases. These indicators may always
be present but sometimes may only occur occasionally at specific
times throughout the day. Heart rate is monitored to assess the
health of a subject or the significance of heart abnormalities. Data
acquisition of this caliber can have profound advancements in the way heart
conditions are understood and treatments are developed.
Monitoring
heart rate variability may be time consuming and difficult without the right
tools in place.
How
heart rate variability works
The
base of your heart rate is located in the
sinoatrial (SA) node of the heart. In this node, cells continuously generate an
electrical impulse which is spread through the entire heart muscle, causing a
contraction. The number of electrical impulses generated per minute is
equivalent to the heart beats per minute.
The autonomic nervous system largely controls the heart rate and
rhythm of the heart, and is broken down into two separate areas: the
parasympathetic nervous system and the sympathetic nervous system.
The parasympathetic nervous system affects the heart rate
through the release of acetylcholine by the vagus nerve. This can impede
activation of SA node activity and may also decrease HRV.
The sympathetic nervous system impacts the heart rate through a
release of epinephrine and norepinephrine. This usually increases activity of
the SA node and may increase HRV.
How
BIOPAC fits in
When
performing heart rate variability analysis, the importance of recording proper
data can not be overstated.
"Results
reveal that even a single heart period artifact, occurring within a 2-min
recording epoch, can lead to errors of estimate heart period variability that
are considerably larger than typical effect sizes in psychophysiological
studies."
—Berntson
& Stowell, 1998
