Figure 16 k

An electrocardiogram of a patient with sinus nodal dysfunction and first-degree atrioventricular block who has an implanted VVI pacemaker. Note that application of a magnet causes VVI pacing in the asynchronous mode at a rate of approximately 95 beats per minute. After the magnet is removed, the pacemaker reverts to VVI at 50 beats per minute until the patient's sinus rhythm inhibits pacemaker function.

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