- The heart rate is an invaluable vital sign that is commonly used as part of the assessment of a patient's haemodynamic state.
- 60 - 100bpm
How to Measure
- Count the number of beats over 15, 30 or 60 seconds and multiply to estimate beats per minute.
- Heart rate greater than 100 beats per minute.
Causes of Tachycardia
- Stress - physical exertion, anxiety, emotional stress, trauma, pain
- Haemodynamic insufficiency - hypovolaemia, shock
- Cardiovascular - pulmonary embolism, coronary ischaemia / infarction
- Endocrine - hypoglycaemia, thyrotoxicosis, phaeochromocytoma
- Drugs - beta agonists, anticholinergics, theophylline, caffeine, amphetamine, cocaine, alcohol
- Atrial - atrial fibrillation, atrial flutter, focal atrial tachycardia, multifocal atrial tachycardia
- Junctional - AV nodal reentrant tachycardia, AV reentrant tachycardia
- Ventricular tachycardia
- Heart rate less than 60 beats per minute.
Causes of 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
- Obstructive sleep apnoea
- Raised intracranial pressure
- 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
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.
- 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