Figure 2

LV-based pacing modes markedly improve LV hemodynamic performance compared with RV pacing. Analysis of rats implanted with RV bipolar electrode and LV bipolar electrode. (A) ECG recordings during normal sinus rhythm (NSR) and the various ventricular pacing modes. Note LBBB like QRS pattern during RV pacing and a remarkable QRS shortening during BiV pacing. Note similar timing and morphology of the retrograde p-waves (marked by arrows), indicating that the component of AV-dyssynchrony is similar in all three ventricular modes of pacing. (B) PV-loop recordings during RV pacing, LV pacing and BiV pacing. Note the profound effects of LV pacing and BiiV pacing in comparison with RV pacing.