Computer-Assisted Reporting System for the Follow-up of Patients with Cardiac Pacemakers

The implantation of large numbers of permanent cardiac pacemakers carries with it the responsibility for continual reassessment of all aspects of patient management. Experience with more than 4,000 pacemaker implants and replacements since 1963 has led to the development of a comprehensive computer-assisted data collection, management, and reporting system for the follow-up of patients with cardiac pacemakers. Over a seven-year period, data forms have been developed for the detailed documentation of pre-operative, intraoperative and follow-up information. These were designed in the form of checklists suitable for direct computer entry using mark-sense document readers. Special emphasis has been placed on pre-operative indications, selection of appropriate pacing systems, reliable follow-up methodology, and monitoring the performance of various pulse-generators. This system makes possible the rapid computer production of hospital records and reports to involved physicians and can be used to schedule follow-up assessments as required. The information also can be used for hospital statistics, billing, research, and pacemaker registration at the provincial, state of federal level. Experience has shown that a computer-assisted methodology is the only practical means of providing adequate follow-up for a large group of patients. In addition, direct access to relevant information helps to create an environment in which essential research can be carried out in the face of demanding clinical practice.     

Prospective Evaluation of Defibrillation Threshold and Postshock Rhythm in Young ICD Recipients

Background: Adaptation of implantable cardioverter defibrillator (ICD) systems to the needs of pediatric and congenital heart patients is problematic due to constraints of vascular and thoracic anatomy. An improved understanding of the defibrillation energy and postshock pacing requirements in such patients may help direct more tailored ICD therapy. We describe the first prospective evaluation of defibrillation threshold (DFT) and postshock rhythm in this population. Methods: We prospectively studied patients ≤60 kg at time of ICD intervention. DFTs were obtained using a binary search protocol with three VF inductions. Postshock pacing was programmed using a stepwise protocol, lowering the rate prior to each VF induction. Results: Twenty patients were enrolled: 11 had channelopathy, five congenital heart disease, and four cardiomyopathy. The median age was 16 years, median weight 48 kg. Twelve patients had a transvenous high‐voltage coil; eight had pericardial +/? subcutaneous coil(s). Median DFT was 7 J (range 3–31 J); 19/20 patients had DFT ≤15 J and all patients <25 kg had DFT ≤9 J (n = 6). There was no difference in DFT between patients with transvenous versus pericardial +/? subcutaneous coils (median 7 J vs 6 J, P = 0.59). No patient with normal atrioventricular conduction prior to defibrillation required postshock pacing (n = 16). There were no adverse events. Conclusions: These data suggest that many pediatric ICD patients have low DFTs and adequate postshock escape rhythm. This may help determine appropriate parameters for future design of pediatric‐specific ICDs. (PACE 2012;35:1487–1493)     

Improved Efficacy of Mode Switching During Atrial Fibrillation Using Automatic Atrial Sensitivity Adjustment

Automatic mode switching (AMS) during atrial fibrillation (AF) in a dual chamber pacemaker is dependent on the accurate detection of an atrial electrogram. As atrial amplitude is often reduced during AF compared with sinus rhythm, this may result in failure of the AMS and a rapid ventricular response. In addition, undersensing of AF may result in competitive atrial pacing that sustains AF. We hypothesize that the use of automatic atrial sensitivity adjustment (ASA) may enhance AF sensing in a dual chamber pacemaker. We studied the AMS response with and without ASA of the Marathon DDDR (model 294–09, Intermedics, Inc.) pacemaker in 10 patients with paroxysmal AF. Intracardiac atrial electrograms during sinus rhythm and induced AF were recorded onto an analog tape recorder. They were replayed into the pacemaker to assess the AMS response at various starting atrial sensitivities from 3.5 to 0.8 mV with ASA activated and without. Atrial amplitude was reduced during AF. The higher the initial atrial sensitivity, the better is the AMS response and the lower the incidence of AF undersensing. The percentage of AMS before ASA ranged from 2.1% at an atrial sensitivity 3.5 mV to 95.6% at highest sensitivity of 0.5 mV (P < 0.05). After 10 minutes of ASA, the AMS response was improved from 1.7% to 50.6% and from 9.5% to 50.9% at starting atrial sensitivities of 3.5 mV and 2.5 mV, respectively (P < 0.05 in both instances). Undersensing during AF was also significantly reduced after ASA from 70% to 10% at a sensitivity of 3.5 mV and from 33.8% to 10.8% at 2.5 mV. There was no increase in oversensing. In four patients with paroxysmal AF with an implanted pacemaker, ASA improved AMS response in patients with a low implant atrial amplitude. In conclusion, efficacy of mode switching and AF sensing are dependent on the programmed atrial sensitivity, which can be enhanced with the use of ASA, particularly when P wave sensing during AF is borderline.