Overview
The heart rate is an invaluable vital sign that is commonly used as part of the assessment of a patient's haemodynamic state.
Normal Range
- 60 - 100bpm
How to Measure
- Count the number of beats over 15, 30 or 60 seconds and multiply to estimate beats per minute.
Tachycardia
Heart rate greater than 100 beats per minute.
Causes of Tachycardia
Sinus Tachycardia
- Stress - physical exertion, anxiety, emotional stress, trauma, pain
- Fever
- Haemodynamic insufficiency - hypovolaemia, shock
- Anaemia
- Cardiovascular - pulmonary embolism, coronary ischaemia / infarction
- Endocrine - hypoglycaemia, thyrotoxicosis, phaeochromocytoma
- Drugs - beta agonists, anticholinergics, theophylline, caffeine, amphetamine, cocaine, alcohol
Other Rhythms
- Atrial - atrial fibrillation, atrial flutter, focal atrial tachycardia, multifocal atrial tachycardia
- Junctional - AV nodal reentrant tachycardia, AV reentrant tachycardia
- Ventricular tachycardia
Bradycardia
Heart rate less than 60 beats per minute.
Causes of Bradycardia
Sinus Bradycardia
- Sinus node disease - idiopathic degeneration, myocardial infarction, infiltration, connective tissue disease, cardiac surgery, Lyme disease, endocarditis
- Physiological - high cardiac fitness
- Autonomic - neurocardiogenic syncope, carotid sinus hypersensitivity
- Drugs - beta blockers, calcium channel blockers, digoxin, adenosine, ivabradine, clonidine, acetylcholinesterase inhibitors
- Hypothyroidism
- Hypothermia
- Hyperkalaemia
- Obstructive sleep apnoea
- Raised intracranial pressure
Other Rhythms
- Sinus node - sinus arrhythmia, sinus arrest, second or third degree sinoatrial exit block
- Atrial - atrial fibrillation with slow ventricular response, atrial flutter with variable block, trial escape rhythm
- AV node - second or third degree atrioventricular block, junctional escape rhythm
- Ventricular escape rhythm
Postural Tachycardia
How To Elicit
- Measure the heart rate with the patient lying down, and then remeasure it after the patient has been standing for one minute.
Interpretation
- Postural tachycardia is present if there is a rise of >20bpm following standing.
Causes of Postural Tachycardia
- Reduced intravascular volume - dehydration, haemorrhage
- Cardiac - congestive cardiac failure, cardiomyopathy, myocarditis, constrictive pericarditis, aortic stenosis
- Drugs - nitrates, anticholinergics, antidepressants, antihypertensives, levodopa
- Prolonged bed rest
- Alcohol
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