1. A Different Approach to the Analysis of Pure Ventricular Parasystole
Agustin Castellanos, MD, FCCP, Federico Moleiro, MD, FCCP, Alberto Interian, MD, Robert J. Myerburg, MD 
CHEST 
Volume 107, Issue 5, Pages (May 1995)
DOI: /chest
Copyright © 1995 The American College of Chest Physicians Terms and Conditions

2. FIGURE 1
Artificial ventricular parasystole occurring when a nonsensing pacemaker (VVI) provided unintentional fixed rate (VOO) pacing. In both (noncontinuous) strips (lead 2), there was coexistence of sinus and parasystolic rhythms. Note that, consistently, there were three values for sinus beats interposed between consecutive manifest parasystolic beats (NISB). The corresponding values were 0, 2, and 3. TE=ectopic cycle length; TS=sinus cycle length; RP=ventricular refractory period.
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Copyright © 1995 The American College of Chest Physicians Terms and Conditions

3. FIGURE 2
Graph obtained from a mathematical model of pure ventricular parasystole showing the allowed number of sinus beats between manifest parasystolic beats in the so-called tE (ectopic cycle length)/ts (sinus cycle length); θ (ventricular refractory period)/ts plane. For each region, the allowed numbers are indicated by three integers separated by commas. The values expected from the calculations performed in Figure 1 fall in the site indicated by the X. The values obtained from the electrocardiographic tracings coincide with those predicted by the mathematical model (0,2,3) (from Gordon et al,3 with permission).
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Copyright © 1995 The American College of Chest Physicians Terms and Conditions