Pacemaker Operating Modes
1 - Chamber paced
A (atrium), V (ventricle), D (dual/both)
2 - Chamber sensed
A, V, D, O (if sensing is temporarily disabled)
3 - Response to sensed events
I - Inhibits pulse in response to sensed event
T - Triggers pulse in response to sensed event (A triggered only response has no clinical purpose)
D - Pulses can be either inhibited or triggered
O - No response to sensed events
4 - Rate modulation
R - Paced rate changes based on perceived physiologic need
(4th position is left blank if this function is not present)
Timing:
• Lower rate limit (50-60 bpm) - The lowest rate at which the device will allow the heart to beat
• Maximum tracking rate (a.k.a. upper rate limit) (120-130 bpm) - The fastest rate at which the device will pace the heart
• AV Delay (150-200 bpm) - The period of time the pacemaker waits after a sensed or paced atrial depolarization before pacing the ventricle if intrinsic ventricular conduction is not sensed
• Post-ventricular atrial refractory period (PVARP) (250-300 bpm) - The period of time after ventricular depolarization during which an atrial impulse sensed by the atrial lead will be ignored for timing cycle purposes. (PVARP is a safety feature: prevents sensing and inappropriate tracking of retrograde P waves which would trigger pacemaker-mediated tachycardia)
Additional Settings:
• Sensitivity - The voltage a lead must measure in order to respond to an intrinsic depolarization (i.e. either inhibit or trigger a pacing spike)
• Output - The voltage the pacemaker delivers to the myocardium in order to initiate depolarization (programmed as voltage x pulse width)
• Mode Switching - Mode can automatically change with changes in heart rhythm
- Dr. Eric Strong @DrEricStrong - Strong Medicine https://www.youtube.com/c/EricsMedi
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