Fully Inhibited Dual Chamber Pacing Mode

Abstract

A pacing mode is provided, in one embodiment, that permits missed or skipped ventricular beats. The mode monitors a full cardiac cycle (A-A interval) for the presence of intrinsic ventricular activity. If ventricular activity is present, a flag is set that is valid for the next cardiac cycle. At the beginning of the next cardiac cycle, the device determines if the flag is present. So long as the flag is present, the device will not deliver a ventricular pacing pulse in that cycle, even if there is no intrinsic ventricular activity. If there is no flag present at the start of a given cardiac cycle, a ventricular pacing pulse is delivered and this ventricular activity sets a flag for the subsequent cardiac cycle.

1 . A method of selectively providing cardiac pacing with an implantable medical device comprising: 
 setting a flag during a given cardiac cycle in response to ventricular activity; and    precluding a ventricular pacing pulse during a current cardiac cycle if the flag is present at the onset of the current cardiac cycle.    
   
   
       2 . The method of  claim 1 , wherein the flag is valid only for a cardiac cycle immediately succeeding the given cycle.  
   
   
       3 . The method of claim 1 , wherein the flag is valid only for one cardiac cycle subsequent to the given cardiac cycle.  
   
   
       4 . The method of  claim 1 , wherein the given cardiac cycle is defined by an A-A interval.  
   
   
       5 . The method of  claim 4 , wherein the ventricular activity may occur at any time during the A-A interval to set the flag.  
   
   
       6 . The method of  claim 1 , further comprising initiating an atrial escape interval at a start of the current cardiac cycle if the flag is present at the onset of the current cardiac cycle.  
   
   
       7 . The method of  claim 6 , further comprising: 
 delivering an atrial pacing pulse at the initiation of the atrial escape interval.    
   
   
       8 . The method of  claim 7 , wherein an intrinsic atrial depolarization initiates the atrial escape interval.  
   
   
       9 . The method of  claim 8 , wherein a scheduled atrial pacing pulse is inhibited.  
   
   
       10 . The method of  claim 1 , further comprising: 
 initiating an AV interval if, at the onset of the current cardiac cycle, the flag is absent;    delivering a ventricular pacing pulse at the expiration of the AV interval;    setting the flag for a subsequent cardiac cycle; and    initiating a VA interval with the delivered ventricular pace.    
   
   
       11 . The method of  claim 10 , further comprising: 
 restarting the VA interval if ventricular activity is sensed during the VA interval.    
   
   
       12 . The method of  claim 10 , further comprising: 
 mode switching to a dual chamber mode for at lease one cardiac cycle subsequent to delivering the ventricular pacing pulse.    
   
   
       13 . A computer readable medium including instructions that define a pacing mode that when implemented on an implantable medical device cause the implantable medical device to: 
 set a flag in response to ventricular activity occurring in a current cardiac cycle, wherein the flag is valid for a subsequent cardiac cycle;    determine if a flag is present at the start of a given cardiac cycle;    initiate an atrial escape interval if the flag is present at the start of the given cardiac cycle;    initiate an AV interval if no flag is present at the start of the given cardiac cycle;    deliver a ventricular pacing pulse at the completion of the AV interval; and    initiate a VA interval at the completion of the AV interval.    
   
   
       14 . The computer readable medium of  claim 13 , wherein the ventricular activity includes a ventricular pace or intrinsic ventricular depolarization.  
   
   
       15 . The computer readable medium of  claim 13 , wherein the AV interval is 80 ms.  
   
   
       16 . The computer readable medium of  claim 13 , wherein no ventricular pace is delivered during the atrial escape interval.  
   
   
       17 . The computer readable medium of  claim 13 , wherein sensed ventricular activity occurring during the VA interval will restart the VA interval.  
   
   
       18 . The computer readable medium of  claim 13 , wherein a second ventricular sense during the given cardiac cycle will terminate the atrial escape interval and initiate and VA interval.  
   
   
       19 . The computer readable medium of  claim 18 , wherein a third or subsequent ventricular sense during the given cardiac cycle will restart the VA interval.  
   
   
       20 . The computer readable medium of  claim 13 , wherein a first atrial sense or a first ventricular sense will inhibit a scheduled pacing pulse and initiate the subsequent interval.  
   
   
       21 . The computer readable medium of  claim 13 , further comprising instructions to cause the implantable medical device to: 
 mode switch to a dual chamber mode for at least one cardiac cycle immediately subsequent to the cardiac cycle in which the ventricular pacing pulse was delivered.    
   
   
       22 . A method of operating an implantable medical device in a mode, the method comprising: 
 setting a flag during a first cardiac cycle if a pre-established criteria is met during the first cardiac cycle;    determining whether the flag has been set at the initiation of a second cardiac cycle that is consecutive to the first cardiac cycle;    acting in a first manner during the second cardiac cycle and while remaining in the mode if the flag has been set;    acting in a second manner during the second cardiac cycle and while remaining in the mode if the flag has not been set.    
   
   
       23 . The method of  claim 22 , wherein setting the flag includes placing information in a memory.  
   
   
       24 . The method of  claim 22 , wherein setting the flag includes removing information from a memory.  
   
   
       25 . The method of  claim 22 , wherein the flag is valid only for the second cardiac cycle.  
   
   
       26 . The method of  claim 22 , wherein the pre-established criteria is the presence of ventricular activity.  
   
   
       27 . The method of  claim 26 , wherein the ventricular activity includes ventricular pacing or sensed intrinsic depolarization.  
   
   
       28 . The method of  claim 22 , wherein acting in the first manner includes initiating an atrial escape interval.  
   
   
       29 . The method of  claim 28 , wherein ventricular pacing is precluded during the atrial escape interval.  
   
   
       30 . The method of  claim 22 , wherein acting in the second manner includes: 
 initiating an AV interval;    delivering a ventricular pacing pulse at the expiration of the AV interval; and    initiating a VA interval.    
   
   
       31 . The method of  claim 30 , further comprising: 
 setting a second flag during the second cardiac cycle in response to the ventricular pacing pulse, wherein the second flag is only valid for a third cardiac cycle that is consecutive to the second cardiac cycle.    
   
   
       32 . An implantable medical device (IMD) having mode-switching capability for delivering pacing therapy in a selected mode, comprising: 
 an atrial lead;    a ventricular lead;    a memory;    a processing module in electronic communication with the ventricular lead and the memory wherein the processing module sets a flag in the memory during a first cardiac cycle if a pre-established criteria is sensed or delivered via the ventricular lead during the first cardiac cycle and determines whether the flag has been set at the initiation of a second cardiac cycle that is consecutive to the first cardiac cycle; and    a controller that initiates an atrial escape interval and precludes ventricular pacing during the second cardiac cycle and while remaining in the selected mode if the flag has been set and the controller initiates an AV interval and a ventricular pacing pulse during the second cardiac cycle and while remaining in the selected mode if the flag has not been set.    
   
   
       33 . A method of selectively providing cardiac pacing with an implantable medical device comprising: 
 setting a flag during a given cardiac cycle in response to ventricular activity; and    delivering a ventricular pacing pulse during a current cardiac cycle only if a flag is absent at the onset of the current cardiac cycle.