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What are the variations in pulse rate?

Definition of pulse rate 
It is defined as the number of beats per minute. Normally it ranges between 60 to 100 beats per minute with average 72 beats per minute in an adult. Usually it remains 130 beats per minute at birth.

How to count the pulse rate?
You should count the pulse rate for one full minute by palpating the radial artery 
Normal pulse rate is 60 - 100 per minute
Sinus bradycardia - pulse rate < 60 per minute
Sinus tachycardia - pulse rate > 100 per minute.

What is Tachycardia ?
Tachycardia is defined as pulse rate above 100 per minute. Normally this is found in children.Following are the causes of tachycardia

a. Sinus tachycardia 
Pulse rate is above 100 per minute with the impulse is originating from the SA node. Ihe heart rate in sinus tachycardia varies between 100-160 per minute. The common causes of sinus tachycardia are given below 
Physiological causes of Sinus tachycardia
  • Infants
  • Children
  • Emotion
  • Exertion.
Pathological causes of sinus tachycardia 
  • High output states: anaemia, fever, beriberi, thyrotoxicosis, pheochromocytoma, arteriovenous fistula. 
  • Tachyarrthmias: Supraventricular, ventricular.
  • Acute anterior wall myocardial infarction,cardiac failure, cardiogenic shock.myocarditis
  • Hypovolemia, hypotension.
  • Drugs (atropine, nifedipine, beta agonists salbutamol, thyroxine, catecholamines, nicotine,caffeine).
b.Relative tachycardia 

c. Paroxysmal tachycardia 
Pulse rate is above 160 beats per minute. It is classified  into two types:
1) Supraventricular (PSVT) [atrial (PAT) or nodal (PNT)].
2) Ventricular (VT).
Common causes of paroxysmal tachycardia are the following rheumatic carditis, ischaemic heart disease (1HD). thyrotoxicosis, hypertensive heart disease, cardiomyopathy. WPW syndrome.