Pressure (Pulsus) Alternans

Pressure Alternans is a sign of a failing ventricle. It can be seen in Left Ventricular pressure tracing or arterial waveform (shown above) where it represents severe left ventricular dysfunction. In severe Right ventricular dysfunction, Pulsus or Pressure Alternans can be seen in the Right ventricular pressure tracing recored from a Swan-Ganz catheter.

Notice the beat-to-beat variation in the pressure tracing. Pulsus Alternans is felt to be a manifestation of decreased myocardial contractility. Decreased contractility is attributed to deletion of the number of myocardial cells contracting on alternate beats. Another mechanism which may be involved (to a lesser extent) in creating this effect is an alteration in diastolic volume leading to beat-to-beat variation in preload. (Hemodynamic Rounds, Mort Kern, MD, Wiley-Liss 1993)