Arterial Pulse Types and Pulsus Paradoxus
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Direct answer
Pulsus paradoxus is an inspiratory fall in systolic blood pressure of more than 10 mmHg, seen in cardiac tamponade, severe asthma and COPD. Other pulse types each point to a specific lesion: collapsing pulses in aortic regurgitation, anacrotic pulses in severe aortic stenosis and alternans in severe left ventricular failure. Pulse shape, felt at the carotid or radial artery, gives a quick clue to the valve or chamber problem.
What you must remember
- Collapsing pulse: a quick upstroke and sudden downfall with a wide pulse pressure, seen in aortic regurgitation, patent ductus arteriosus and thyrotoxicosis.
- Anacrotic pulse: a slow-rising, small-volume pulse with a late peak, called pulsus parvus et tardus, from severe aortic stenosis.
- Bisferiens pulse: two systolic peaks, typical of mixed aortic stenosis and regurgitation or hypertrophic obstructive cardiomyopathy.
- Pulsus alternans: a regular rhythm with alternating strong and weak beats, a marker of severe left ventricular systolic failure.
- Pulsus paradoxus: an inspiratory fall in systolic pressure greater than 10 mmHg, from tamponade, severe asthma or COPD.
- Pulsus bigeminus: a pulse that comes in pairs because each premature ventricular beat is followed by a weak beat.
- Beck's triad: hypotension, raised jugular venous pressure and muffled heart sounds, the classic picture of tamponade.
Reading the pulse pattern
Each pulse type reflects a particular stroke volume, ejection pattern or respiratory effect on the heart. The table lists the main patterns with their classic causes.
| Pulse type | Character | Classic cause |
|---|---|---|
| Collapsing | Quick rise, sudden fall, wide pulse pressure | Aortic regurgitation, patent ductus |
| Anacrotic (parvus et tardus) | Slow rise, small volume, late peak | Severe aortic stenosis |
| Bisferiens | Two systolic peaks | Mixed aortic valve disease, HOCM |
| Alternans | Regular rhythm, alternating strong and weak beats | Severe left ventricular failure |
| Paradoxus | Systolic fall greater than 10 mmHg on inspiration | Tamponade, severe asthma |
To measure pulsus paradoxus, inflate the cuff above systolic pressure and deflate it slowly. The difference between the pressure at which sounds are heard only in expiration and the pressure at which they are heard through the whole cycle is the paradoxus. A small inspiratory fall is normal, so the 10 mmHg cut-off matters.
Alternans is most reliably felt when the rhythm is regular, and it signals advanced systolic failure rather than a valve lesion.
Where the exam tries to catch you
Pulse questions in NEET-PG often match a pattern to a valve lesion, so the traps below repeat the classic pairings.
- Trap: any inspiratory fall in pressure is called pulsus paradoxus. Correct: pulsus paradoxus needs a fall greater than 10 mmHg, because normal breathing causes a small drop.
- Trap: a bounding pulse with a high pulse pressure is blamed on hypertension. Correct: a collapsing pulse with a wide pulse pressure points to aortic regurgitation, patent ductus or thyrotoxicosis.
- Trap: alternans is confused with bigeminy. Correct: alternans is a regular rhythm with alternating strong and weak beats, while bigeminy is ectopic-driven pairing of beats.
Frequently asked questions
What is the cut-off for pulsus paradoxus?
Pulsus paradoxus is defined as a fall in systolic blood pressure of more than 10 mmHg during inspiration. It is measured with a sphygmomanometer by comparing the pressure at which sounds appear only in expiration with the pressure at which they are heard throughout the cycle.
Which conditions cause pulsus paradoxus?
Cardiac tamponade is the classic cause of pulsus paradoxus, followed by severe asthma and COPD exacerbations. Constrictive pericarditis can produce it less often, so the finding alone does not separate these conditions.
What pulse is seen in severe aortic stenosis?
Severe aortic stenosis produces a slow-rising, small-volume pulse with a late peak, called pulsus parvus et tardus. The carotid upstroke is the best place to feel this pattern at the bedside.
What is pulsus bisferiens and where is it seen?
Pulsus bisferiens is a pulse with two systolic peaks, seen in mixed aortic stenosis and regurgitation and in hypertrophic obstructive cardiomyopathy. It reflects a sharp early peak followed by a second wave in the same systole.
How does pulsus alternans differ from pulsus bigeminus?
Pulsus alternans is a regular rhythm with alternating strong and weak beats, a marker of severe left ventricular systolic failure. Pulsus bigeminus is a pattern of paired beats caused by premature ventricular ectopics, in which each premature beat is followed by a weak pulse.