Figure 16 u

Electrocardiogram marker channels of a patient with a dual-chamber pacemaker. Note that the atriaL pacing outputs (APs) are capturing the atrium, and there is appropriate P-wave sensing (As or AR). However, none of the ventricular outputs are capturing the ventricle. This is a tracing of a patient who had a pacemaker placed 3 weeks prior to acquisition of this ECG, and the pacing threshold had exceeded the tracing output.

Mitrani,R.D. and others,Cardiac Pacemakers,Hurst's The Heart,10th edition,Vol.1,pp.963-992