Specifications

Post-Ventricular Atrial Refractory Period
The Post-Ventricular Atrial Refractory Period (PVARP) follows a paced,
sensed, or refractory sensed ventricular event in the DDDR, DDD, DDIR,
DDI, and VDD modes. It is intended primarily to prevent the sensing of
retrograde P-waves that might promote Pacemaker-Mediated Tachycardias
(PMTs) in atrial tracking modes. In the DDIR and DDI modes, PVARP
prevents atrial inhibition from retrograde P-waves.
The first portion of the PVARP is the programmable Post-Ventricular
Atrial Blanking period (PVAB). During the remainder of the PVARP,
intrinsic atrial events may be sensed as refractory sensed events (AR) and
identified on Marker Channel recordings and Marker Channel Diagrams,
but they do not affect stimulus timing. That is:
■
In the DDDR, DDD, and VDD modes, a SAV is not started.
■
In the DDDR, DDD, DDIR, and DDI modes, the scheduled atrial pace
is not inhibited.
Example of PVARP Operation
The duration of the PVARP may be selected as follows:
■
The PVARP should be programmed to a value greater than the
patient’s retrograde (VA) time when retrograde conduction is present.
■
Excessively long PVARPs may induce 2:1 block at high intrinsic rates
in atrial tracking modes (DDDR, DDD, and VDD).
Pacemaker Timing 12-17
9879EN-12_9501043EN/CTC.qxd 5/10/99 11:27 Page 12-17
P
P
DDD
A
V
P
PVARP
7 x 9 inches (178 mm x 229 mm)
Medtronic Confidential
Refer to the “Reference man.” category in doc#163256 for Printing
Instructions.
196407001 Rev A