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Heart Rate
Variability (HRV),
Heartbeats, and
Autonomic Nervous
System (ANS)
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(professionals and
individuals) for
experience sharing and
in-depth discussions at  
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Do you have     
- are you monitoring   
- are you taking
prescription drugs?
- are you aware of drug
side effects on ANS?
- self-improvement tips
Read more......
Feeling dizzy      
or even fainted?
- are you low in blood
pressure or heart rate?
- are you taking
prescription drugs?
- You may experience
Baroreflex failure
Read more......
Irregular heartbeats?
- often noticing abnormal
heartbeats (missing,
uneven, or super-fast)?
- Yo might have cardiac
- Most sudden death
events are preceded by
irregular heartbeats
Read more......
Mitral Valve Prolapse?
- Mitral valve is the
bicuspid valve between left
atrium and ventricle
- If mitral valve is not
closed properly (called
mitral valve prolapse
MVP), the blood may
backflow during pumping
- there is a strong
connection between panic
attackes and MVP
- How to detect it?
Read more......
Am I having   
- autonomic nervous
system works to fine tune
body conditions depending
on physiological needs
- ANS consists of two
branches: sympathetic and
- do you have balanced
- what are the symptoms of
Read more......
What is Autonomic Nervous System (ANS)?
Glimpse of Facts on ANS

  • The autonomic nervous system (ANS ) is the part of the peripheral nervous system that acts as
    a feedback control system
  • ANS functions below the level of consciousness.  Its actions are mostly involuntary and
  • ANS controls 90% of body and mental activities, including heart rate, respiration rate, digestion,
    and sexual arousal (see Table 1 below)
  • ANS is divided into two subsystems: the sympathetic nervous system (SNS) and
    parasympathetic nervous system (PNS).  Both are opposing in general, but sometimes
    complimenting and cooperating to meet physiological needs (see Figure 1)
  • SNS responds to “fight or flight” and acts as an accelerator, while PNS responds to “rest and
    digest” and acts as a brake
  • The primary function of the immune system is to keep virus, bacteria, and foreign matters from
    invading the body;  In contrast, ANS’s main functions is to help body cope with internal and
    external changes
  • Some people manage stress better than others.  An efficient ANS system might be the
  • Several uncomfortable or complex symptoms are due to ANS imbalance or dysautonomia
Figure 1: Autonomic Nervous System
Table 1: Main Functions of Autonomic Nervous System
In-depth Understanding of ANS
Autonomic Nervous System (see Figure 2 below)
  • The autonomic nervous system conveys sensory impulses from the blood vessels, the heart and all of the organs in
    the chest, abdomen and pelvis through nerves to other parts of the brain (mainly the medulla, pons and
  • These impulses often do not reach our consciousness, but elicit largely automatic or reflex responses through the
    efferent autonomic nerves
  • Thereby eliciting appropriate reactions of the heart, the vascular system, and all the organs of the body to
    variations in environmental temperature, posture, food intake, stressful experiences and other changes to which all
    individuals are exposed.
  • The above information is cited from Wilson-Pauwels ; Stewart•Akesson: Autonomic Nerves. 1997
Figure 2: The Feedback Loop of Autonomic
    Nervous System
  • When resting, our body maintains a constant and stable condition called
    “Homeostasis”; Body temperature, blood pressure, cardiac output, respiration,
    and endocrine secretions are controlled by negative feedback mechanisms
  • ANS is the primary system responsible for these feedback mechanisms

  • At resting and under homeostasis, ANS is at balance with LF/HF close to 1.0
  • When the body conducts a specific activity, ANS provides timely and proper
    support (Sympathetic nerve activated during exercise; Parasympathetic nerve
    activated during recovery)
  • When the body is off balance or unhealthy, ANS becomes over-active or under-
    active in certain branches (Depression causes parasympathetic withdrawal;
    Lack of sleep decrease overall ANS function)

  • HRV parameters reflect the present activities exerted by ANS
  • Deviation of any HRV parameter from normal or baseline value is an indication of
    abnormal ANS activity
  • Homeostatic patient parameters (such as BP, heart rate, body temperature)
    may still be normal
  • HRV parameters are early indicators of body stress and disease
Homeostasis, ANS, and HRV
ANS Imbalance or Dysautonomia
Conventional definition of ANS imbalance /
  • fast heart rate, shortness of breath, dizzy/lightheaded, weak, fatigued/exhausted
    ,  memory loss, chest discomfort/pain, anxiety, palpitations,  nausea, vomiting,
    bloating, abdominal pain, diarrhea, and constipation (Using a standard  
    dysautonomia scale to obtain a total score)

Definition of ANS imbalance / dysautonomia by HRV
  • Any severe deviation of HRV parameters from normal values can be judged as
    ANS imbalance or dysautonomia
  • Normal values can be obtained from the HRV-Age-Sex correlation (see Figure 3)

Cause of ANS imbalance / dysfunction
  • ANS exhibits unusual or extraordinary activities in order to support, supplement,
    or compensate other organ systems in unhealthy states - Most frequently
    encountered (about 80% of dysautonomia cases in our clinical observation)
  • ANS itself has incomplete, imbalanced, deteriorated, or damaged functions
    (insufficient or  excessive secretion of neurotransmitters, defected receptors,
    neuropathy, spinal lateral bending) – Less frequent (about 20% among
    dysautonomia cases)
  • Genetic factors play an important role

Read more on Dysautonomia at Dysautonomia Information Network
Figure 3: HRV-Sex-Age Correlations (Normal
  • The above statistical correlation is established by taking HRV data
    published in literature for healthy volunteers and conducting regression
    analysis (30 peer-reviewed journal papers covering world-wide regions and
    demographics including our own published data; report on file with Sun
  • 1996 International HRV Standard does provide certain HRV normal ranges.  
    However, the range is too broad to be useful as a guide for health status