Ventricular depolarization pacemaker sensing

Fig. 7.7 (A) Twelve-lead ECG during pacing demonstrates left bundle-branch block morphology and inferiorly directed mean frontal plane axis, suggesting that the pacing electrode is in the right ventricular outflow tract. (B) Pacing lead placement in the right ventricular apex is indicated by the left bundle branch block morphology and the mean frontal plane superior axis. Notice that the pacemaker does not sense the premature ventricular depolarization (fourth QRS complex in all leads), which indicates that the sensitivity should be increased (by reducing the sensitivity value).

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