Apparatus and methods for automatic adjustment of av interval to ensure delivery of cardiac resynchronization therapy

Abstract

Methods and apparatus of left ventricular pacing including automated adjustment of a atrio-ventricular (AV) pacing delay interval and intrinsic AV nodal conduction testing. Thus, in the event that the AV conduction test reveals a physiologically acceptable intrinsic PR interval then storing the physiologically acceptable PR interval in a memory structure (e.g., a median P-R from one or more cardiac cycles) and delivering fusion pacing using a decremented value of the intrinsic PR interval.

1 . A method of ventricular pacing including automated adjustment of atrio-ventricular (AV) pacing delay intervals and intrinsic AV nodal conduction testing comprising performing the following steps:
 (a) measuring an based upon timing of atrial depolarizations and depolarizations of a first ventricular chamber;   (b) responsive to the measured intrinsic PR interval falling within a defined range for said ventricular chamber, storing the measured intrinsic PR interval in a memory structure; and   (c) decrementing the stored intrinsic PR interval to define pre-excitation intervals (PEI) following subsequent atrial depolarizations;   (d) delivering fusion pacing pulses to a second ventricle on expirations of the PEI until expiration of: (i) a preset number of cardiac cycles or (ii) a preset time; and   (e) responsive to the expiration, repetition of steps a), b), c) and d).   
     
     
         2 . A method according to  claim 1 , wherein the measured intrinsic atrio-ventricular (PR) interval comprises an average of intervals between atrial depolarizations and depolarizations of the first ventricular chamber. 
     
     
         3 . A method according to  claim 1 , wherein the measured intrinsic atrio-ventricular (PR) interval comprises a weighted average of intervals between atrial depolarizations and depolarizations of the first ventricular chamber. 
     
     
         4 . A method according to  claim 1  wherein responsive to AV conduction block, the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         5 . A method according to  claim 1  wherein responsive to AV conduction block, the delivery of Bi-Ventricular pacing pulses is initiated. 
     
     
         6 . A method according to  claim 1  wherein responsive to unacceptably long intrinsic PR intervals, the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         7 . A method according to  claim 1  wherein responsive to unacceptably long intrinsic PR intervals, the delivery of Bi-Ventricular pacing pulses is initiated. and the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         8 . A method according to  claim 1  wherein responsive to unacceptably long intrinsic PR intervals, the delivery of Bi-Ventricular pacing pulses is initiated and the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         9 . A method according to  claim 1  wherein responsive to unacceptably long intrinsic PR intervals, the delivery of Bi-Ventricular pacing pulses is initiated and the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         10 . A method of ventricular pacing including automated adjustment of atrio-ventricular (AV) pacing delay intervals and intrinsic AV nodal conduction testing comprising performing the following steps:
 (a) measuring an intrinsic atrio-ventricular (PR) interval based upon timing of atrial depolarizations and depolarizations of a first ventricular chamber;   (b) responsive to the measured intrinsic PR interval falling within a defined range for said ventricular chamber, storing the measured intrinsic PR interval in a memory structure; and   (c) decrementing the stored intrinsic PR interval to define pre-excitation intervals (PEI) following subsequent atrial depolarizations;   (d) delivering fusion pacing pulses to a second ventricle on expirations of the PEI;   (e) detecting loss of capture of the second ventricle; and responsive to the detected loss of capture, repetition of steps a), b), c) and d).   
     
     
         11 . A method according to  claim 10 , wherein the measured intrinsic atrio-ventricular (PR) interval comprises an average of intervals between atrial depolarizations and depolarizations of the first ventricular chamber. 
     
     
         12 . A method according to  claim 10 , wherein the measured intrinsic atrio-ventricular (PR) interval comprises a weighted average of intervals between atrial depolarizations and depolarizations of the first ventricular chamber. 
     
     
         13 . A method according to  claim 10  wherein responsive to AV conduction block, the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         14 . A method according to  claim 10  wherein responsive to AV conduction block, the delivery of Bi-Ventricular pacing pulses is initiated. 
     
     
         15 . A method according to  claim 10  wherein responsive to unacceptably long intrinsic PR intervals, the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         16 . A method according to  claim 10  wherein responsive to unacceptably long intrinsic PR intervals, the delivery of Bi-Ventricular pacing pulses is initiated. and the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         17 . A method according to  claim 10  wherein responsive to unacceptably long intrinsic PR intervals, the delivery of Bi-Ventricular pacing pulses is initiated and the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         18 . A method according to  claim 10  wherein responsive to unacceptably long intrinsic PR intervals, the delivery of Bi-Ventricular pacing pulses is initiated and the preset time or preset number of cardiac cycles (AVEI) is incremented. 
     
     
         19 . A method of ventricular pacing including automated adjustment of atrio-ventricular (AV) pacing delay intervals and intrinsic AV nodal conduction testing comprising performing the following steps:
 (a) providing a stored data set of physiological responses and corresponding re-excitation intervals) PEI;   (b) measuring an intrinsic atrio-ventricular (PR) interval based upon timing of atrial depolarizations and subsequent depolarizations of a first ventricular chamber;   (c) responsive to the measured intrinsic PR interval falling within a defined range for said ventricular chamber, storing the measured intrinsic PR interval in a memory structure; and   (d) decrementing the stored intrinsic PR interval to define effective pre-excitation intervals (PEI) following subsequent atrial depolarizations;   (e) delivering fusion pacing pulses to a second ventricle on expirations of the effective PEI;   (f) detecting an occurrence of a physiological response within the stored data set, and   (g) responsive to the detection, setting the corresponding stored PEI as the effective PEI and subsequently delivering pacing pulses to the second ventricle on expirations of the effective PEI.   
     
     
         20 . A method according to  claim 19  wherein the physiologic response trigger comprises one of an upward or downward heart rate excursion, a sensed lack of ventricular synchrony.