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

Pathophysiology

One explanation is that in left ventricular dysfunction, the

ejection fraction An ejection fraction (EF) is the volumetric fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or heartbeat). It can refer to the cardiac atrium, ventricle, gall bladder, ...

will decrease significantly, causing reduction in stroke volume, hence causing an increase in

end-diastolic volume In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right or left ventricle at end of filling in diastole which is ammount of blood present in ventricle at the end of diastole systole. Because greater EDVs cause g ...

. 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. There may initially be a tachycardia as a compensatory mechanism to try to maintain cardiac output. Other explanation is due to the heterogeneity of the refractory period between the healthy and diseased myocardial cells.

Diagnosis

Begin by palpating the radial or femoral arteries, feeling for a regular rhythm but alternating strong and weak pulses. Next use a blood pressure cuff to confirm the finding: Inflate the blood pressure cuff past systolic pressure and then slowly lower cuff pressure towards the systolic level. If alternating loud & soft

Korotkoff sounds Korotkoff sounds are the sounds that medical personnel listen for when they are taking blood pressure using a non-invasive procedure. They are named after Nikolai Korotkov, a Russian physician who discovered them in 1905, when he was working at t ...

are heard, pulsus alternans is indicated.

Clinical significance

A finding of pulsus alternans is indicative of severe left-sided heart failure. (Bates)

In literature

D.H. Lawrence David Herbert Lawrence (11 September 1885 – 2 March 1930) was an English writer, novelist, poet and essayist. His works reflect on modernity, industrialization, sexuality, emotional health, vitality, spontaneity and instinct. His best-k ...

elegantly describes pulsus alternans in his novel '' Sons and Lovers'':

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

External links

Cardiovascular diseases {{med-sign-stub