Heart rate variability

Humans have studied heart rate variability (HRV) in its simplest form for thousands of years simply by noticing the quickening of the pulse rate after the increase of exercise or other forms of arouse states.

Heart rate variability is defined as the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the variation in the beat-to-beat interval.

HRV serves as important index of pathological changes and is use to diagnose cardiovascular risk in man. The more regularly one’s heart beats, the lower is one’s HRV, and the less regularly one’s heart beats, the greater is one’s HRV.

It is also known to predict illness before any physical symptoms emerge, which means that it can also be used to quantify risk of ill health.
Heart rate variability

Sinus tachycardia

Sinus tachycardia (also colloquially known as sinus tach or sinus tachy) is a physiological mechanism occurring appropriately in response to sympathetic activation and/or parasympathetic withdrawal, such as during exercise, anxiety, pain, hypovolemia, orthostatic hypotension, fever, infections, heart failure, pericarditis, diabetes-related autonomic dysfunction, drug abuse, catecholamine infusions, anticholinergic drugs, tobacco, caffeine, alcohol and beta-blocking agent withdrawal.

It is a sinus rhythm with an elevated rate of impulses, defined as a rate greater more than 100 beats/min (bpm) in an average adult. The normal resting heart rate in the average adult ranges from 60–100 bpm.

Inappropriate sinus tachycardia is a form of focal atrial tachycardia originating along the superior aspect of the crista terminalis in the “sinus node region” at rates above physiologic range, without relation to metabolic or physiologic demands. Sinus tachycardia is inappropriate when there is no known cause for the sinus tachycardia, Inappropriate sinus tachycardia occurs usually in young females in their 30s.
Sinus tachycardia