1. The Implantable Starr-Edwards Pacemaker
A. Castellanos, M.D., F.C.C.P., A. Ghahramani, M.D., R.J. Sung, M.D., R.J. Myerburg, M.D. 
CHEST 
Volume 68, Issue 4, Pages (October 1975)
DOI: /chest b
Copyright © 1975 The American College of Chest Physicians Terms and Conditions

2. FIGURE 1
During sinus rhythm, small “tracking pulses”3 or “blips”5 are seen on ascending portion of second, third, 11th, and 12th R waves. In contrast, pacemaker-induced (fifth to ninth) QRS complexes are preceded by large stimulus artifacts.
CHEST  , DOI: ( /chest b)
Copyright © 1975 The American College of Chest Physicians Terms and Conditions

3. FIGURE 2
Magnification of last part of Figure 1. First QRS complex is pacemaker escape; it is followed by three sinus beats. Distortion produced by small “tracking pulses”3 or “blips”5 is more marked in fourth and fifth R waves than in third R wave.
CHEST  , DOI: ( /chest b)
Copyright © 1975 The American College of Chest Physicians Terms and Conditions