HEART RATE VARIABILITY

• DATTARAJ . SANSGIRI –10-548

• RAGHAV. NARASIMHAN – 11-501

• JUI . AGAM – 11-502

Variations in time interval between heartbeats.

Measured by variations in beat-tot-beat interval.

This is done either by using ECG recording or PPG graphs or Blood Pressure curves.

ECG recording along with Blood Pressure curves is used normally to be accurate.

The Sino-Atrial node generates such impulses 100-120 times per min !!!

Sympathetic Nervous

• Fight and Flight.

• Stimulates heart’s functioning.

• High sympathetic stimulation = High Heart Rate and Stroke Volume.

• Heart’s response to Sympathetic Stimulation =

5 secs.

Para-Sympathetic Nervous

• Calmness and Rest.

• Inhibits heart’s functioning.

• Acts only after Sympathetic Stimulation has taken place.

• Heart instantaneouslyresponds to para-Sympathetic Stimulation

Bio-feedback mechanism.

When changes are monitored and displayed on a computer screen, clearly indicate how radically our thoughts and emotions affect the heart and nervous system.

Factors affecting normal functioning of the Heart :

Respiration

Thermoregulation

Blood Pressure

Cardiac Output.

TIME – DOMAIN ANALYSIS

FREQUENCY – DOMAIN ANALYSIS

Calculates a number of variables that describe either the heart rate at any time or determine the intervals between successive normal complexes.

In a continuous electrocardiographic (ECG) recording each QRS complex is detected and the normal-to-normal (N-N) intervals or the instantaneous heart rate are determined.

TIME DOMAIN ANALYSIS

Some simple calculated time domain variables include :

Mean NN interval

Mean heart rate

Difference between the shortest and the longest N-N interval

Standard deviation of N-N intervals (SDNN) (estimate of overall HRV)

HRV triangular index (estimate of overall HRV)

Standard deviation of averages of N-N intervals (SDANN)

(estimate of long-term components of HRV)

Square root of the mean of squared deviation(RMSSD)(estimate of short-term components HRV).

Acting like a mirror reflecting emotional states this real time feedback can help us prevent, manage and reverse the harmful effects of stress and negative emotions.

It is believed that Heart Rate Variability (HRV) will become as common as pulse, blood pressure or temperature in patient charts in the near future.

It is found that lowered HRV is associated with aging, decreased autonomic activity, hormonal tonus, specific types of autonomic neuropathies (e.g. diabetic neuropathy) and increased risk of sudden cardiac death after acute heart attack.

Heart rate variability (HRV), a measure of autonomic function, can predict survival outcomes.

Heart rate, measured as beat-to-beat intervals, is not constant and varies in time. This property is known as heart rate variability (HRV) and it has been investigated in several diseases.

These include :

Diabetes

Cardiovascular Diseases

Myocardial Infraction

Detecting Cancer

As a complication of diabetes mellitus, Autonomic Neuropathy is developed.

Early and widespread neuronal degeneration of small nerve fibres of both sympathetic and parasympathetic tracts.

Reduced heart rate recovery (HRR) in coronary artery disease (CAD) is predictive of increased cardiovascular mortality and is related to reduced parasympathetic tonus.

HRR and HRV are significantly reduced in CAD.

The reduction in HRR is parallel to the changes in HRV parameters.

HRR, which can be measured easily in the recovery phase of exercise testing, can be used to detect the depression of parasympathetic tonus and to evaluate the basal autonomic balance in this patient group.

It is well-known that HRV is the strongest indicator of the autonomic function. Lowering certain HRV parameters may tell us that parasympathetic tonus is in trouble.

It cannot be used to make specific diagnoses. It serves as a strong marker of the autonomic health and estimates the possibility of developing cancer when the autonomic function is chronically low.

Helps catching a negative tendency in the autonomic function way before the first symptoms of cancer may occur.

RAGHAV.NARASIMHAN

BE – BIOM