The carotid pulse should be used when assessing the character of the pulse, which refers to the strength or volume of a pulse. The character of a pulse can suggest various pathologies.
Waterhammer/Large volume pulse
Cause: Aortic regurgitation
Cause: Aortic stenosis
Cause: Aortic stenosis with aortic regurgitation
Occurs in left ventricular systolic impairment. The pulse alternates between low and high volume; a low ejection fraction produces the low volume pulse, which leads to ventricular filling and stronger contraction due to Startling’s law in the subsequent pulse.
A large drop in pulse volume (corresponding to >10mmHg blood pressure) upon inspiration.
- Pericardial effusion
- Severe asthma
Double impulse apex beat
Cause: Hypertrophic obstructive cardiomyopathy (HOCM)
Absent radial pulse
Occasionally, a radial pulse may be completely absent and cannot be palpated or found on ultrasound.
- Iatrogenic e.g. post-catheterisation, radial artery harvest
- Congenital absence
- Aortic dissection involving the subclavian artery
- Peripheral artery embolism
- Compression by cervical rib
- Takayasu’s arteritis