The RYTHMIQTM algorithm aims to minimize right ventricular pacing and has been implemented in modern Boston Scientific dual-chamber pacemakers and implantable cardioverter-defibrillators. When the atrioventricular conduction is preserved, the RHYTHMIQTM algorithm operates in AAI mode with VVI back-up pacing and switches to DDD mode if a loss of atrioventricular conduction is suspected. While in DDD mode, the AV Search +™ algorithm is used to search for restored atrioventricular conduction with periodic automatic extension of the AV interval. By design, the algorithm cannot switch from DDD to AAI without this AV search+ phase (basically 300ms AV delay, looking for 25 VS but stops if 2VP within a rolling window of 10 ventricular cycles).
Here you can clearly see that the device goes from DDD (last VP, first strip) to AAI with VVI back-up (following AS and VS). How can it be?
The only thing I could think of was a manual programing of the RYTHMIQ in a dependant patient paced in DDD. Actually this is the case: this tracing has been recorded during the device interrogation/programming, the day of the implant. This is a funny behavior of BS scientific devices to store events which occured during the manual interrogation.
If you have any question about this tracing don't hesitate. Please send us your tracing too!
DR Sylvain Ploux
Sun, 20/12/2015 - 09:48
Hello,
The RYTHMIQTM algorithm aims to minimize right ventricular pacing and has been implemented in modern Boston Scientific dual-chamber pacemakers and implantable cardioverter-defibrillators. When the atrioventricular conduction is preserved, the RHYTHMIQTM algorithm operates in AAI mode with VVI back-up pacing and switches to DDD mode if a loss of atrioventricular conduction is suspected. While in DDD mode, the AV Search +™ algorithm is used to search for restored atrioventricular conduction with periodic automatic extension of the AV interval. By design, the algorithm cannot switch from DDD to AAI without this AV search+ phase (basically 300ms AV delay, looking for 25 VS but stops if 2VP within a rolling window of 10 ventricular cycles).
Here you can clearly see that the device goes from DDD (last VP, first strip) to AAI with VVI back-up (following AS and VS). How can it be?
The only thing I could think of was a manual programing of the RYTHMIQ in a dependant patient paced in DDD. Actually this is the case: this tracing has been recorded during the device interrogation/programming, the day of the implant. This is a funny behavior of BS scientific devices to store events which occured during the manual interrogation.
If you have any question about this tracing don't hesitate. Please send us your tracing too!
S Ploux