Figure 5.

Tracking check algorithm; 1 — atrial mechanical ventricular pacing (AM-VP) rhythm at or above the tracking check rate; 2 — after the median ventricular rate reaches tracking check rate, the tracking check extends the post-ventricular atrial refractory period (PVARP) until the following AM occurs within; 3 — the tracking check estimates the location of the next AM; 4 — AM occurs in the expected range — appropriate tracking is confirmed, and the PVARP is returned to its basic value. Copyright Medtronic. Used with permission [30]; ECG — electrocardiogram; AR — atrial refractory sensing.