Figure 4. Bradycardia and high grade block develop just prior to death after weekly LPS.

Telemetry tracings from a mouse that died 57 days after weekly LPS 20 mg/kg i.p. Each strip is 2.5 seconds. The top panel shows the baseline ECG at 10 pm, 18 hours prior to death, with a heart rate of 640 beats per minute (bpm). The mouse had normal activity. The remaining panels show telemetry tracings during last two hours before death. At 3:09 pm, there was a junctional tachycardia at 720 bpm with a shift in the QRS axis, consistent with increased automaticity from another region or fascicle. One hour later at 4:04 pm, sinus rhythm returned (with p waves) at 540 bpm. However 1.5 hours later at 5:34 pm, episodes of high grade block occurred with sustained bradycardia at 384 bpm, then 10 minutes later at 5:44 pm progressive high grade AV block and an idioventricular escape rhythm just prior to death.