Expansion
Stroke volume divided by arterial compliance
Expansion
Pulse pressure = systolic - diastolic, normally about 40 mmHg, and it is determined by stroke volume divided by arterial compliance.
Widened pulse pressure:
- Aortic regurgitation, where diastolic pressure falls as blood leaks back
- Arterial stiffening with age, causing isolated systolic hypertension
- High output states: anaemia, thyrotoxicosis, pregnancy, sepsis, arteriovenous fistula
- Patent ductus arteriosus
Narrowed pulse pressure:
- Hypovolaemia and any low stroke volume state
- Aortic stenosis
- Cardiac tamponade and constrictive pericarditis
- Severe heart failure
A narrowing pulse pressure is an early and often overlooked sign of haemorrhage, appearing before the systolic pressure falls, because compensatory vasoconstriction raises the diastolic value while stroke volume is already falling.