Mintek Pacemaker LV-T Manuale Utente

76  Stratos LV/LV-T Technical Manual   

Sensed events that occur during the refractory period have no 
effect on pacemaker timing.  These atrial or ventricular sensed 
events are classified as “unused” for normal CRT-P timing. 

In the Stratos CRT-Ps, the total atrial refractory period has been 
subdivided into an atrial refractory period (ARP), atrial far-field 
protection (FFP) and a PMT protection window (PMT).  In terms 
of priority FFP is first, ARP second and PMT third. 

When mode switching is turned ON, the atrial events in the atrial 
refractory period and the PMT protection window are used as the 
criteria in order to sense atrial tachyarrhythmias and to ensure 
high atrial rates are not transmitted to the ventricle. 

The behavior of BIOTRONIK CRT-Ps reacts differently 
depending on the timing interval in which the atrial event occurs.  
The behavior is summarized in Table 20. 

A

s

 occurs during 

the far-field 
protection (FFP) 

No consequence.  A

s

 is ignored (unused).  

Neither the AV delay nor the ARP is 
started.  There is no influence on mode 
switching. 

A

s

 occurs during 

the Atrial 
Refractory 
Period (ARP) 

The event influences mode switching. 

A

s

 occurs in the 

PMT protection 
window 

The AUI (atrial upper interval) starts.  The 
AV delay is not restarted.  Post-AES 
pacing is started if the atrial sense is 
classified as an AES. 

 

2.3.6.1  Atrial Refractory Period 
In all modes in which atrial depolarization can be sensed, the 
Stratos CRT-Ps will start an atrial refractory period upon each 
atrial depolarization (programmable: AUTO, 225…(25)…775).  In 
standard “Auto” setting, the atrial refractory period (ARP) is 
automatically preset to a minimum value of 225 ms and is 
automatically extended if the AV delay is longer.