Reuse of Explanted DDD Pacemakers as VDD--论文代写范文精选

心脏起搏器是昂贵的设备,不过一般人别无选择。在许多情况下，对于心脏起搏器病人,，处理仍处于良好状态的起搏器将是一个浪费。然而心脏起搏器的重用与广泛的技术、医学、伦理和法律方面相关。

Abstract
Re-use of DDD pulse generators explanted from patients died of unrelated causes is associated with an additional cost of two transvenous leads if implanted as DDD itself, and high rate of infection according to some studies. We studied the clinical and economical aspects of reutilization of explanted DDD pacemakers programmed to VDD mode. Out of 28 patients who received VDD pacemaker during the period, October 2000- September 2001 in the Department of Cardiology, PGIMER, Chandigarh, 5 poor patients were implanted with explanted DDD pulse generators programmed to VDD mode. Each implantation was planned and carried out according to a standard protocol. The age ranged from 45 to 75 (mean-61) years. The indications for pacing were complete heart block (4) and second degree AV block (1). The clinical profile, costs and complications, if any were noted and followed up at regular intervals. The results were compared with patients who received new DDD pulse generators during this period. The additional cost for the atrial lead was not required in these patients. None of these patients had any local site infection. Compared to the two-lead system, the single lead system provided more rapid implantation and minimized complications associated with placement of an atrial lead. The explanted DDD pacemaker can be safely reused as VDD mode with same efficacy in selected patient population. This is associated with lower cost and complications compared to reimplantation as DDD itself.
Key words: Explanted pacemakers, VDD, DDD

Introduction
Technology is outpacing the financial resources available for health care all over the world. Pacemakers are among the expensive devices, and when indicated properly they have no alternative. In many instances pacemakers outlive the patients and it would be a waste to dispose these pacemakers that are still in good condition having considerable battery life left without allowing others to benefit.  However the reuse of pacemakers is associated with widespread technical, medical, ethical and legal considerations.

Reuse of DDD pulse generators explanted from patients dying of unrelated causes is associated with an additional cost of two transvenous leads, if reimplanted in DDD mode itself. There are also reports of unacceptably high rates of infection associated with reuse of explanted pacemakers. We studied the clinical and economical aspects of utilization of explanted DDD pacemakers programmed to VDD mode.
Materials and methods

During the period October 2000 to December 2001 (15 months) the patients who received pacemakers in PGIMER, Chandigarh were studied. Out of these patients, those who received generators explanted from patients who had died of unrelated causes were noted. We used explanted dual chamber pulse generators (Medtronic, Prodigy DR, model 7860, bipolar) after programming to VDD mode, with the use of new VDD lead (58-13.5-9F) in poor patients who could not afford a new pulse generator. Appropriate preprocedural evaluation was done in these patients to achieve optimal patient selection for VDD mode. The pulse generators had been explanted postmortem from patients who died of causes other than pacemaker failure after informed consent from the nearest relative. The generators were properly cleansed in antiseptic solution and sterilized with ethylene oxide and reliably tested for function and battery life. The recipient’s consent was also sought after proper explanation of the risks and benefits.

These patients were followed up after one month of implantation initially and three monthly thereafter. They were compared with those patients who received DDD pacing during the same period regarding cost, complications and procedural time. To assess the quality of life (QOL), a standard questionnaire (Table1) was given to the patients during their last follow up visit of the study period. The questionnaire contained 7 questions, 3 related to the general QOL and 4 specific to the pacemaker related symptoms. Each question contained 4 responses, the individual score varying from 1-4 according to severity. The total score in each patient was calculated.

Discussion 
We studied 5 patients who received explanted DDD programmable pulse generators, which were programmed to VDD mode prior to implantation. Analysis of cost effectiveness and safety in these poor and unaffordable patients revealed that these generators can be safely and effectively used at a significantly lower cost.

The rationale for the reuse of pacemakers is based on the following facts. The current lithium battery pacemakers have an expected life greater than 10 yrs. In high-risk subgroups of patients with coronary artery disease and atrioventricular block, the 3-year mortality approaches 60%1 and thus many pacemakers would have more than 5 years of life left when the recipients die. Pringle et al reported a mortality rate of 58% within 2 years of last generator implant based on a retrospective examination of 169 consecutive pacemaker patient-deaths2. It should also be noted that in patients with severe cardiac diseases such as heart failure and cardiomyopathy, more sophisticated pacemakers are often implanted, and these patients do die earlier from their original disease. Thus the waste of pacemaker life is aggravated.

Mugica et al reviewed over 3,500 patients who had a 10-year follow up and reported no significant difference in the actuarial survival of those patients given explanted generator compared to those received newer one 3. Rosengarten et al observed similar incidence of pacemaker related complications and survival among new and refurbished pacemakers in a prospective comparative study over a mean follow up period of 36 months4. Such experiences have repeatedly confirmed that when properly carried out, re-use of pacemakers does not pose any additional risk with considerable reduction in cost. The lack of widespread acceptance of pacemaker re-use is, therefore, not alone due to technical or medical considerations, but is related to ethical and legal problems associated with this approach. 

The ethical and legal issues involve both the retrieval of a still usable pacemaker from a deceased patient and the selection of the patient to receive such a pacemaker. In countries such as Sweden, pacemakers are considered to be the property of the state and can be removed routinely without the need for consent from the families of patients who have died. In many other countries including Canada, US and India, once the pacemaker has been implanted regardless of the source of funding for this procedure, the device is considered to belong to the patient. Retrieval of such a device therefore requires the consent of the next of kin or the living will of the patient. In view of theoretical risks of reimplantation of cadaveric explants, informed consent of the recipient also should be sought, after proper explanation of possible risks involved in the re-use.

The clinical problem of reuse of pacemaker in the recipient is mainly based on the rate of infection and battery life. The risk of re-use is that an instrument might be improperly selected due to an inaccurate history of use, or improperly cleansed, tested or sterilized. Explanted pacemakers should be considered for re-use only when the reliable clinical record indicates that the instrument has had no malfunction and has an arbitrarily set minimum battery life of 5 years. After proper electronic testing, the pulse generators are to be washed under sterile conditions in distilled water and then gas sterilized with ethylene oxide for two hours at 55°C and 60% humidity. The device is released for implantation after essential aeration for 48 hours at 55°C in an aeration device or in the appropriate sterilizer. Mond et al described a high rate of infection with the reuse of explanted pacemakers5. Based on a retrospective case control study, which involved 100 patients who received re-used pacemakers, Linde et al concluded that the re-use of pacemakers could be carried out without increased risk to the patient provided a proper routine for technical control and sterilization is followed6. Experiences of other authors have also confirmed the short- and long-term safety of re-use of cadaveric explants7,8,9. 

None of our patients had local site infection. Battery life of the pulse generators was properly assessed prior to implantation by a pacing system analyzer in all. The average battery life of these 5 pulse generators at the time of implantation was 89.4months (at 60 bpm, output 4 V, pulse width 0.4 ms and VDD mode). The re-use as VDD system resulted in avoiding the need of atrial lead placement leading to reduction in fluoroscopy time and virtual nonexistence of complications related to atrial lead, apart from reducing the cost significantly. The cost reduction by   Rs 16,000/- per patient was significant considering the baseline economic status of these poor patients. There was no significant difference in the duration of hospital stay, need of antibiotics or additional cost to the patients. Proper atrial sensing, the most essential component of VDD pacing was also unaltered on follow up. Similarly, none of these patients had pacemaker syndrome, pacemaker-mediated tachycardia or atrial arrhythmias on follow up. There was no significant difference in the quality of life score between those received explanted pulse generator and newer one.

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