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. The condition is relatively rare, and patients with the greatest risk for developing pulsus alternans include those with heart failure,

cardiomyopathy Cardiomyopathy is a group of primary diseases of the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. A ...

, coronary artery disease, or other cardiac risk factors.

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, cardiac ventricle, gall ...

will decrease significantly, causing reduction in

stroke volume In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the ventricle (heart), ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an Echocardiography, echocardiogram and subtra ...

, 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 amount of blood present in ventricle at the end of diastole. Because greater EDVs cause greater ...

. 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

Pulsus alternans is diagnosed by first palpating the radial or femoral arteries, feeling for a regular rhythm but alternating strong and weak pulses. Next, a blood pressure cuff is used to confirm the finding: the cuff is elevated past systolic pressure and then slowly lowered cuff towards the systolic level. If alternating loud and soft

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

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 novelist, short story writer, poet, playwright, literary critic, travel writer, essayist, and painter. His modernist works reflect on modernity, social alienation ...

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

{{DEFAULTSORT:Pulsus Alternans Cardiovascular diseases