What is the pathophysiology of ventricular premature complexes (VPCs)?

Updated: Nov 26, 2016
  • Author: Jatin Dave, MD, MPH; Chief Editor: Jose M Dizon, MD  more...
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Answer

Very few studies have evaluated the pathophysiology of VPCs in human subjects. Most of the information is derived from animal studies. Three common mechanisms exist for VPCs, (1) automaticity, (2) reentry, and (3) triggered activity, as follows:

  • Automaticity: This is the development of a new site of depolarization in nonnodal ventricular tissue, which can lead to a VPC. In animal models, focal mechanisms without evidence of macro-reentry play a major role in the origin of ventricular arrhythmia associated with ischemic cardiomyopathy. Increased automaticity could be due to electrolyte abnormalities or ischemic myocardium.

  • Reentry circuit: Reentry typically occurs when slow-conducting tissue (eg, infarcted myocardium) is present adjacent to normal tissue. The slow-conducting tissue could be due to damaged myocardium, as in the case of a healed MI.

  • Triggered activity: After depolarizations triggered by a preceding impulse can lead to premature activation if the threshold is reached, and this can cause a VPC. Afterdepolarization can occur either during (early) or after (late) completion of repolarization. Early afterdepolarizations commonly are responsible for bradycardia associated VPCs, but they also can be present with ischemia and electrolyte abnormalities.


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