Pulsus alternans

mechanical alternans

Conspectus

 * Pulsus alternans was first described by Ludwig Traube in 1872 and defined as the beat-to-beat variability of the pulse amplitude in a patient with a sinus rhythm, independent of the respiratory cycle.
 * Only the strong beats but not the weak beats are appreciated as phase I Korotkoff sounds when the cuff pressure is initially lowered.
 * Pulsus alternans reflects myocardial dysfunction associated with cyclic fluctuations in preload, afterload, and contractility.
 * Pulsus alternans typically occurs with heart failure and may be precipitated by aortic regurgitation, hypovolemia, and tachycardia.

Associated Conditions

 * Aortic regurgitation
 * Ectopic beats in aortic stenosis
 * Hypovolemia
 * Left ventricular heart failure
 * Sympathetic activation in myocardial ischemia
 * Tachycardia

Related Chapters

 * Cardiac alternans
 * Electrical alternans

Suggested Readings

 * http://www.ncbi.nlm.nih.gov/pubmed/10533597
 * http://www.ncbi.nlm.nih.gov/pubmed/1634690