Stratos LV/LV-T Technical Manual 125

5.3Testing for Retrograde Conduction

Retrograde conduction from the ventricle to the atrium can be assumed when a 1:1 relationship between the ventricular stimulation and atrial depolarization has been obtained with a constant coupling interval during ventricular stimulation. The Stratos CRT-Ps feature a test for measuring retrograde conduction time. During operation of this test, the patient is paced at an increased ventricular rate over several cycles while the retrograde conduction time is measured.

Both the programmer display and printout provide measured retrograde conduction times (minimum, mean and maximum). The duration of time that the test is conducted may be selected.

To prevent retrograde P-waves from triggering ventricular pulses, thereby mediating a “re-entry” tachycardia (pacemaker mediated tachycardia, PMT), the programmed post-ventricular atrial refractory period must be longer than the retrograde conduction time.

5.4Non-Invasive Programmed Stimulation (NIPS)

WARNING

NIPS - Life threatening ventricular arrhythmias can be induced by stimulation in the ventricle. Ensure that an external cardiac defibrillator is accessible during tachycardia testing. Only physicians trained and experienced in tachycardia induction and reversion protocols should use non- invasive programmed stimulation (NIPS).

5.4.1 Description

The implanted CRT-P/lead system may be used in conjunction with the programmer to generate externally controlled pacing pulses. Burst Stimulation or Programmed Stimulation may be selected with up to four extra stimuli at pacing rates to 800 ppm.