Apparatus and methods of adjusting atrioventricular pacing delay intervals in a rate adaptive pacemaker

Abstract

Provided herewith are methods and apparatus for optimizing an atrioventricular (AV) pacing delay interval. One manner described involves dynamically programming an AV interval in cardiac resynchronization therapy (CRT) device having a rate-adaptive AV (RAAV) feature in such a way that not less than a minimum AV interval is maintained. That is, the AV interval is not allowed to be reduced so much that the P-wave is truncated by the QRS complex. In this form of the invention, the AV interval is reduced by one millisecond per one bpm increase in heart rate (and vice versa for reducing heart rate) but maintained at a value calculated from the end of the P-wave (PWend) and the beginning of the QRS complex (QRSbeg) or delivery of a ventricular pacing stimulus or to the end of the end of the QRS complex (QRSend).

1 . An apparatus for adjusting rate-adaptive atrioventricular (RAAV) pacing interval in a triple chamber cardiac resynchronization therapy (CRT) delivery device, comprising:
 means for measuring a heart rate change of a subject receiving pacing therapy from an implanted pacing device that includes an active rate-adaptive AV (RAAV) interval feature;   means for determining the end of a P-wave (PWend) for an atrial depolarization;   means for determining one of a beginning of a QRS complex (QRSbeg) and an end of the QRS complex (QRSend) accompanying the P-wave; and   means for limiting adjustment of an operating AV interval by the RAAV interval feature to maintain a lower limit on time elapsed between PWend and one of the ending of the QRSbeg, QRSend, and delivery of a ventricular pacing stimulus to preserve atrial-ventricular filling characteristics.   
   
   
       2 . An apparatus according to  claim 1 , further comprising:
 means for calculating a sensed-AV (SAV) interval based upon the operating AV interval value.   
   
   
       3 . An apparatus according to  claim 2 :
 wherein the calculated SAV interval is decremented in the event that the changing heart rate indicates an increasing HR.   
   
   
       4 . An apparatus according to  claim 3 , wherein the SAV interval is decremented between about 0.25 milliseconds (ms) and about 3 ms for each additional beat per minute (bpm) the HR increases. 
   
   
       5 . An apparatus according to  claim 1 , further comprising:
 means for calculating a paced-AV (PAV) interval based upon the operating AV interval value.   
   
   
       6 . An apparatus according to  claim 5 , wherein the calculated PAV interval is decremented in the event that the HR excursion indicates an increasing HR. 
   
   
       7 . An apparatus according to  claim 6 , wherein the PAV interval is decremented between about 0.25 milliseconds (ms) and about 3 ms for each additional beat per minute (bpm) the HR increases. 
   
   
       8 . A method of adjusting a rate-adaptive atrio-ventricular (RAAV) pacing interval in pacing therapy delivery device, comprising:
 measuring a heart rate change of a subject receiving pacing therapy from an implanted pacing device that includes an active rate-adaptive AV (RAAV) interval feature;   determining the end of a P-wave (PWend) for an atrial depolarization;   determining one of a beginning of the QRS complex (QRSbeg) and an end of the QRS complex (QRSend) accompanying the P-wave; and   limiting adjustment of an operating AV interval by the RAAV interval feature to maintain a lower limit on time elapsed between PWend and one of the ending of the QRSbeg, QRSend, and delivery of a ventricular pacing stimulus.   
   
   
       9 . A method according to  claim 8 , further comprising:
 calculating one of a sensed-AV (SAV) interval and a paced-AV (PAV) interval based upon the operating AV interval value.   
   
   
       10 . A method according to  claim 9 , wherein one of the calculated SAV and the calculated PAV interval is decremented in the event that the HR excursion indicates an increasing HR. 
   
   
       11 . A method according to  claim 10 , wherein one of the SAV interval and the PAV interval is decremented between about 0.25 milliseconds (ms) and about 3 ms for each additional beat per minute (bpm) the HR increases. 
   
   
       12 . A method according to  claim 8 , further comprising:
 calculating a paced-AV (PAV) interval based upon the operating AV interval value.   
   
   
       13 . A method according to  claim 8 , wherein the heart rate excursion is measured via a temporary cardiac sensing lead. 
   
   
       14 . A method according to  claim 8 , wherein the heart rate excursion is measured via a temporary pacing and sensing lead in electrical communication with the heart. 
   
   
       15 . A method according to  claim 8 , wherein the heart rate excursion is measured via a chronic pacing and sensing lead in communication with the heart. 
   
   
       16 . A method according to  claim 8 , wherein the heart rate excursion is measured via a subcutaneous cardiac sensing array in a position spaced from, but in electrical communication with, the heart. 
   
   
       17 . A method according to  claim 8 , wherein the heart rate excursion is measured via at least one surface sensing electrode in communication with the heart. 
   
   
       18 . A method according to  claim 8 , wherein the heart rate excursion is measured via a temporary pacing lead in communication with the heart. 
   
   
       19 . A computer medium for storing executable instructions operable under computer processor control to adjust a rate-adaptive atrioventricular (RAAV) pacing therapy delivery device, comprising:
 instructions for measuring a heart rate change of a subject receiving pacing therapy from an implanted pacing device that includes an active rate-adaptive AV (RAAV) interval feature;   instructions for determining the end of a P-wave (PWend) for an atrial depolarization;   instructions for determining one of the beginning of a QRS complex (QRSbeg) and the end of the QRS complex (QRSend) accompanying the P-wave; and   instructions for limiting adjustment of an operating AV interval by the RAAV interval feature to maintain a lower limit on time elapsed between PWend and one of the ending of the QRSbeg, QRSend, and delivery of a ventricular pacing stimulus.   
   
   
       20 . A computer readable medium according to  claim 19 , further comprising:
 instructions for calculating one of a sensed-AV (SAV) interval and a paced-AV (PAV) interval based upon the operating AV interval value.   
   
   
       21 . An apparatus adapted to control adjustment of a rate-adaptive atrioventricular (RAAV) interval in an implantable pacing therapy delivery device, comprising:
 a pair of electrodes adapted to measuring a heart rate change of a subject receiving pacing therapy from an implanted pacing device that includes an active rate-adaptive AV (RAAV) interval feature;   means for determining the end of a P-wave (PWend) for an atrial depolarization;   circuitry adapted to measure one of the beginning of a QRS complex (QRSbeg) and the end the QRS complex (ORSend) accompanying the P-wave; and   means for instructions for limiting adjustment of an operating AV interval by the RAAV interval feature to maintain a lower limit on time elapsed between PWend and one of the ending of the QRSbeg, QRSend, and delivery of a ventricular pacing stimulus.