Pulsus alternans

Pulsus alternans
Pulse pressure waveform displaying the variation in pressure between beats in pulsus alternans.
Classification and external resources
DiseasesDB	11040

Pulsus alternans is a physical finding with arterial pulse waveform showing alternating strong and weak beats.^[1] It is almost always indicative of left ventricular systolic impairment, and carries a poor prognosis.

Pathophysiology

In left ventricular dysfunction, the ejection fraction will decrease significantly, causing reduction in stroke volume, hence causing an increase in end-diastolic volume. There may initially be a tachycardia as a compensatory mechanism to try to keep the cardiac output constant. As a result, during the next cycle of systolic phase, the myocardial muscle will be stretched more than usual and as a result there will be an increase in myocardial contraction, related to the Frank–Starling physiology of the heart. This results, in turn, in a stronger systolic pulse .

Physical examination

Arterial waveform.

Palpate radial or femoral arteries, feel for regular rhythm but alternating strong and weak pulses Use blood pressure cuff to confirm: Raise blood pressure cuff to over systolic level then, lower slowly towards the systolic level, if hearing alternating loud & soft korotkoff sounds, pulses alternans is indicated.^[2]

Clinical significance

Indicative of severe Left-sided heart failure ^[3]

In literature

D.H. Lawrence, in his famous novel, "Sons and Lovers" elegantly describes pulsus alternans:

"Then he felt her pulse. There was a strong stroke and a weak one, like a sound and its echo. That was supposed to betoken the end."

References

1. Euler, DE (June 1999). "Cardiac alternans: mechanisms and pathophysiological significance.". Cardiovascular research 42 (3): 583–90. doi:10.1016/s0008-6363(99)00011-5. PMID 10533597.
2. Bates
3. (Bates)