Identification of pacemaker dependent patients by serial decremental rate inhibition

Abstract

In a study of the concept of pacemaker dependence, 86 patients who had permanent ventricular demand (VVI) pacemakers implanted for more than six months and were in predominantly paced rhythm underwent repeated interruption of pacing both abruptly and after gradual reduction of paced rate. Non-invasive pace slowing was accomplished by timed inhibiting pulses applied to the chest wall. The results identified a small group (A) of patients, 8% of those tested, who consistently failed to develop an adequate escape rhythm and may thus be considered highly pacing dependent. A second group B, 26%, developed an adequate intrinsic rhythm with serial decremental rate inhibition (SDRI) but suffered symptoms with abrupt complete inhibition (ACI). The remaining 66%, group C, developed no symptoms in any test. Analysis of clinical pre-test data showed that syncope, atrioventricular block and a low rate prior to implant, and a long duration of pacing were associated with a higher degree of pacing dependence, but were not reliably predictive. The clinical significance and value of the results are discussed. We conclude that SDRI is a reliable test for the high degree of pacemaker dependence and can be helpful especially in planning a procedure which may involve interruption of pacing.

New Onset of Pacemaker Dependency After Permanent Pacemaker Implantation

“…The detection method of pacemaker dependency in the pacemaker clinic is also important. Compared with the sudden cessation of pacing, a gradual slowing of the pacing rate used in the present study allows the more consistent emergence of an escape rhythm in highly pacemaker dependent patients, 3 therefore, it is safer and better tolerated by patients. Backup temporary pacing at a rate of 30 beats/min for the evaluation of pacemaker dependency is also reliable, since patients who have a stable infranodal escape rhythm are reported to be unaffected by overdrive pacing at a rate of ≤50 beats/min 8 , 10 …”

“…Permanent pacemaker recipients who have no intrinsic or escape rhythm may develop complications under conditions of electromagnetic interference, lead dysfunction, or battery depletion. Few studies have examined the incidence of pacemaker dependency after device implantation 1‐3 . A recent report from the Canadian Trial of Physiologic Pacing (CTOPP) Investigators indicated that pacemaker dependency, defined as an intrinsic heart rate ≤60 beats/min, has an important influence on cardiovascular and total mortality, as does the selection of pacing mode 1 .…”

“…Similarly, a history of symptoms or signs of an emergent nature in the absence of pacing may constitute pacemaker dependency. However, different methods have been applied to evaluate pacemaker dependency, 2‐4 and there is no consensus with respect to its definition. This complicates the clinician's attempts to identify the patients at highest risk in the event of a sudden failure of the pacing system.…”

The Recall Genie:

“…For all of its importance to clinical research 5,6 and recall there are limited published studies on how bradycardia dependency should be measured or on the stability of the measurements 7 . Why, for example, should one consider only the extreme of 30 beats/min as dependence?…”

“…For all of its importance to clinical research 5,6 and recall there are limited published studies on how bradycardia dependency should be measured or on the stability of the measurements. 7 Why, for example, should one consider only the extreme of 30 beats/min as dependence? Many active elderly patients may have a significant clinical sequel to a sudden switch to 40 beats/min or to even faster escape rates.…”