Heart Rate
How to Measure
- Count the number of beats over 15, 30 or 60 seconds and multiply to estimate beats per minute.
Normal Range
- 60 - 100bpm
Causes of Bradycardia (
- Physiological - high cardiac fitness
- Beta blockers
- Hypothyroidism
- Raised intracranial pressure
- Heart block
- Sick sinus syndrome
Causes of Tachycardia (>100bpm)
- Sinus tachycardia - physical exertion, infection, anxiety, thyrotoxicosis, stimulant drugs, shock
- Atrial fibrillation / flutter - aberrant conduction, parenchymal damage
- Supraventricular tachycardia - aberrant conduction pathways/ re-entry
Rhythm
How to Assess
- Feel the pulse for at least thirty seconds and determine whether the beats fall in time or are irregular.
Interpretation
- Regular: sinus rhythm
- Sinus arrhythmia: rhythmic variations in vagal tone with respiration
- Regularly irregular (regular heart rate with occasional missed or extra beats): second degree heart block, premature ventricular contractions
- Irregularly irregular: atrial fibrillation
Character
Weak pulseAtherosclerosis, tamponade, LV failure, cervical rib, aortic dissection, dehydration
Strong pulseExercise, pregnancy, anxiety, fever, hyperthyroidism, acute alcoholism
Waterhammer / collapsing pulse: strong pulse with sudden drop in intensity following its peakAortic regurgitation, patent ductus arteriosus
Pulsus alternans: regular alternation between strong and weak beats, especially palpated in peripheral arteriesLeft ventricular failure
Bisferiens pulse (double beating pulse)Aortic regurgitation
Bigeminal pulse: two close beats followed by a pause.Premature ventricular complexes
Pulsus tardis & parvis: weak pulse with a delayed systolic peak.Aortic stenosis
Pulsus paradoxus: weak pulse during inspiration, strong during expirationConstrictive pericarditis, tamponade, PE, tension PTX, asthma / COPD, shock, pregnancy, obesity
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
- Autonomic dysfunction
- Low intravascular volume - blood / fluid / electrolyte loss
- Vasodilation - nitrates, alcohol, fever
- Cardiac impairment
- Chronic disease - diabetes mellitus, chronic renal failure, chronic liver disease,
- Brain tumour - paraneoplastic syndrome
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