| Pulsus alternans | |
|---|---|
| Other names | Cardiac alternans, mechanical alternans |
 | |
| Pulse pressure waveform displaying the variation in pressure between beats in pulsus alternans. | |
| Specialty | Cardiology |
Pulsus alternans is a physical finding with arterial pulse waveform showing alternating strong and weak beats.[1] It is almost always indicative ofleft 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, coronary artery disease, or other cardiac risk factors.[2]
One explanation is that in left ventricular dysfunction, theejection fraction will decrease significantly, causing reduction instroke volume, hence causing an increase inend-diastolic volume. As a result, during the next cycle ofsystolic phase, themyocardial muscle will be stretched more than usual and as a result there will be an increase in myocardial contraction, related to theFrank–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 therefractory period between the healthy and diseased myocardial cells.[citation needed]
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 softKorotkoff sounds are heard, pulsus alternans is indicated.[3]
A finding of pulsus alternans is indicative of severe left-sided heart failure.[4]
D. H. Lawrence 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....
