System and method for recognizing pacemaker-mediated tachycardia

Claim 1

A system for detecting the occurrence of a pacemaker mediated tachycardia (PMT) in a patient having an implantable pacemaker, said system comprising: first detection means within said implantable pacemaker for detecting a prescribed sequence of cardiac cycles, each cardiac cycle of said prescribed sequence comprising a P-wave followed by a V-pulse at a rate faster than a reference rate, the time interval between said P-wave and said V-pulse of each cardiac cycle comprising a P-V delay; means for momentarily changing said P-V delay in a selected cardiac cycle; and second detection means for detecting if a V-P interval associated with said selected cardiac cycle remains substantially unchanged from a V-P interval associated with at least one cardiac cycle immediately preceding said selected cardiac cycle, said V-P interval comprising the time interval between a V-pulse and a P-wave within a cardiac cycle; a substantially unchanged V-P interval within said changed cardiac cycle providing an indication that said prescribed sequence of cardiac cycles comprises a PMT.

Claim 2

A system for detecting the occurrence of a pacemaker mediated tachycardia (PMT) in a patient having an implantable pacemaker, said system comprising: first detection means within said implantable pacemaker for detecting a prescribed sequence of cardiac cycles, each cardiac cycle of said prescribed sequence comprising a P-wave followed by a V-pulse at a rate faster than a reference rate, the time interval between said P-wave and said V-pulse of each cardiac cycle comprising a P-V delay; means for momentarily changing said P-V delay in a selected cardiac cycle; and second detection means for detecting if a V-P interval associated with said selected cardiac cycle remains substantially unchanged from a V-P interval associated with at least one cardiac cycle immediately preceding said selected cardiac cycle, said V-P interval comprising the time interval between a V-pulse and a P-wave within a cardiac cycle; a substantially unchanged V-P interval within said changed cardiac cycle providing an indication that said prescribed sequence of cardiac cycles comprises a PMT.

Claim 22

A system for detecting the occurrence of a pacemaker mediated tachycardia (PMT) in a patient having an implantable pacemaker, said system comprising: tachycardia detection means for detecting a tachycardia condition in a heart of said patient, said heart having atria and ventricles, said tachycardia condition comprising a plurality of consecutive cardiac cycles that exceed a prescribed rate, each cardiac cycle of said tachycardia condition including a P-wave followed by a V-pulse, the occurrence of said P-wave evidencing a non-paced contraction of the atria, and the occurrence of said V-pulse evidencing a paced contraction of the ventricles, said paced contraction of the ventricles resulting from application of said V-pulse to one of said ventricles, said V-pulse being generated by said pacemaker upon a failure of said pacemaker to sense a natural contraction of the ventricles within a prescribed P-V delay subsequent to sensing said P-wave; modifying means responsive to said tachycardia detection means for modifying said P-V delay for a fixed number of cardiac cycles upon the detection of said tachycardia condition, whereby each of said fixed number of cardiac cycles includes a modified P-V delay; and comparison means for comparing if a second V-P interval occurring after said modified P-V delay remains substantially unchanged relative to a first V-P interval occurring before said modified P-V delay, a V-P interval comprising the time interval between a V-pulse and the subsequent occurrence of a P-wave; a substantially unchanged second V-P interval relative to said first V-P interval providing an indication that said tachycardia condition comprises a PMT.

Claim 23

A system for detecting the occurrence of a pacemaker mediated tachycardia (PMT) in a patient having an implantable pacemaker, said system comprising: tachycardia detection means for detecting a tachycardia condition in a heart of said patient, said heart having atria and ventricles, said tachycardia condition comprising a plurality of consecutive cardiac cycles that exceed a prescribed rate, each cardiac cycle of said tachycardia condition including a P-wave followed by a V-pulse, the occurrence of said P-wave evidencing a non-paced contraction of the atria, and the occurrence of said V-pulse evidencing a paced contraction of the ventricles, said paced contraction of the ventricles resulting from application of said V-pulse to one of said ventricles, said V-pulse being generated by said pacemaker upon a failure of said pacemaker to sense a natural contraction of the ventricles within a prescribed P-V delay subsequent to sensing said P-wave; modifying means responsive to said tachycardia detection means for modifying said P-V delay for a fixed number of cardiac cycles upon the detection of said tachycardia condition, whereby each of said fixed number of cardiac cycles includes a modified P-V delay; and comparison means for comparing if a second V-P interval occurring after said modified P-V delay remains substantially unchanged relative to a first V-P interval occurring before said modified P-V delay, a V-P interval comprising the time interval between a V-pulse and the subsequent occurrence of a P-wave; a substantially unchanged second V-P interval relative to said first V-P interval providing an indication that said tachycardia condition comprises a PMT.

Claim 35

A method for detecting a PMT in a patient having an implanted pacemaker, said method comprising the steps of: (a) sensing a P-wave followed by a V-pulse in a plurality of successive cardiac cycles; (b) sensing if the plurality of successive cardiac cycles sensed in step (a) occurs at a rate in excess of a tachycardia reference rate (TRR); (c) increasing a P-V delay in a single cardiac cycle when the rate of the plurality of successive cardiac cycles sensed in step (b) exceeds the TRR; (d) measuring a V-V time interval associated with said single cardiac cycle, said V-V time interval comprising the elapsed time between a first V-pulse and a second V-pulse, a first P-wave occurring after the first V-pulse and prior to the second V-pulse, the increased P-V delay of step (c) being included in the V-V time interval as the time interval between the first P-wave and the second V-pulse; (e) measuring a P-P time interval associated with said single cardiac cycle, said P-P time interval comprising the elapsed time between said first P-wave and a second P-wave, said second P-wave occurring after the second V-pulse, the increased P-V delay of step (c) being included in the P-P time interval as the time interval between the first P-wave and the second V-pulse; (f) measuring the difference between said V-V time interval and said P-P time interval; and (g) indicating a PMT condition when the difference between said V-V time interval and said P-P time interval is less than a prescribed difference.

Claim 36

A method for detecting a PMT in a patient having an implanted pacemaker, said method comprising the steps of: (a) sensing a P-wave followed by a V-pulse in a plurality of successive cardiac cycles; (b) sensing if the plurality of successive cardiac cycles sensed in step (a) occurs at a rate in excess of a tachycardia reference rate (TRR); (c) increasing a P-V delay in a single cardiac cycle when the rate of the plurality of successive cardiac cycles sensed in step (b) exceeds the TRR; (d) measuring a V-V time interval associated with said single cardiac cycle, said V-V time interval comprising the elapsed time between a first V-pulse and a second V-pulse, a first P-wave occurring after the first V-pulse and prior to the second V-pulse, the increased P-V delay of step (c) being included in the V-V time interval as the time interval between the first P-wave and the second V-pulse; (e) measuring a P-P time interval associated with said single cardiac cycle, said P-P time interval comprising the elapsed time between said first P-wave and a second P-wave, said second P-wave occurring after the second V-pulse, the increased P-V delay of step (c) being included in the P-P time interval as the time interval between the first P-wave and the second V-pulse; (f) measuring the difference between said V-V time interval and said P-P time interval; and (g) indicating a PMT condition when the difference between said V-V time interval and said P-P time interval is less than a prescribed difference.