Pulsus alternans

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Varun Kumar, M.B.B.S.; Mohamed Moubarak, M.D. [2]


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.


The mechanism of pulsus alternans was referred to Starling's law of the heart.[2] The ejection fraction will decrease significantly in cases of left ventricular dysfunction, which is the most important cause of pulsus alternans, causing reduction in stroke volume, and this reduction results in an increase in the end-diastolic volume. As explained by Starling's law, during the next cycle of systolic phase, the myocardial muscle will be stretched more than usual and causes an increase in myocardial contraction, this in turn results in a stronger systolic pulse.

Pulsus alternans trace.jpg



The presence of pulsus alternans almost indicate severe left ventricular failure, and patients should undergo further investigations for proper management.

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Pulsus alternans in itself is not a life threatening condition, but in most of cases it indicate sever left ventricular failure and further investigations should be done.

Common Causes

The most common cause of pulsus alternans is Left ventricular failure, other causes include:

Causes by Organ System

Cardiovascular Cardiac tamponade, Meadows syndrome, premature ventricular contraction, severe aortic regurgitation
Chemical / poisoning No underlying causes
Dermatologic No underlying causes
Drug and Toxin Side Effect No underlying causes
Ear Nose Throat No underlying causes
Endocrine No underlying causes
Environmental No underlying causes
Gastroenterologic No underlying causes
Genetic [No underlying causes
Hematologic No underlying causes
Iatrogenic No underlying cause
Infectious Disease No underlying causes
Musculoskeletal / Ortho No underlying causes
Neurologic No underlying cause
Nutritional / Metabolic No underlying cause
Obstetric/Gynecologic No underlying cause
Oncologic No underlying causes
Opthalmologic No underlying causes
Overdose / Toxicity [No underlying causes
Psychiatric No underlying causes
Pulmonary Asthma
Renal / Electrolyte No underlying causes
Rheum / Immune / Allergy No underlying causes
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous No underlying causes

Causes in Alphabetical Order


  1. Euler D (1999) Cardiac alternans: mechanisms and pathophysiological significance. Cardiovascular Research. Vol. 42. P. 583-590. PMID 10533597
  2. GLEASON WL, BRAUNWALD E (1962). "Studies on Starling's law of the heart. VI. Relationships between left ventricular enddiatolic volume and stroke volume in man with observations on the mechanism of pulsus alternans". Circulation. 25: 841–8. PMID 13899176.

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