Pulse Generator Longevity Research Articles

Reconditioned and new pacemakers in low-resource countries: A pilot study

Abstract Introduction: Cardiac pacemakers have brought a paradigm shift to the management of symptomatic bradyarrhythmia. It has led to a dramatic reduction in morbidity and mortality from cardiovascular disease over the many decades. Despite these merits, pacemakers remain unaffordable and beyond reach for many patients in low-and middle-income countries (LMICs) including Nigeria. These challenges and regulatory obstacles may be overcome with postmortem pacemaker reuse if they are proven to be feasible and safe as cost-effective strategy to provide life-saving therapy to patients in LMICs. The aim of this pilot study was to review the usefulness of reconditioned pacemakers among patients that could not afford new devices. Materials and Methods: A total of 16 patients were recruited for the pilot study. These included patients with a pacing indication who could not afford a new pacemaker or a battery change. The 16 patients were grouped into A and B. Group B had 8 patients that received new pacemaker batteries. Group A comprised 8 patients who received refurbished pacemaker batteries. All the pacemaker leads used in the study for both the groups were new. Implant charges were free. Ethical approval was got from the University of Port Harcourt Teaching Hospital, and the Cardiocare Multispecialty Hospital, Abuja, before commencement of the study. The refurbished pacemaker batteries were donated by the relatives of deceased patients, with a minimum 70% of remaining battery life. The donated pacemaker batteries were received from Pace4 life and My Heart Your Heart, University of Michigan, Michigan, United States. These reconditioned batteries were resterilized. Pacemaker functions were rechecked before and after sterilization. The devices were programmed on nonpacing (ODO) mode with adaptive pacing mode swift off. These devices were shipped to us for use. All sterile techniques were followed during implantation. Data were collected on wound healing and device malfunction during implant and follow-up for 3 months. Results: The average age for the patients was 62 ± 13 years. There was no pocket hematoma among both the groups. There were no complications during the 1–3-month follow-up period. There was no evidence of lead or battery malfunction among the two groups. The means of battery longevity for the new and refurbished pacemakers were 10.38 and 10.57 years, respectively. There was no statistical difference between the pulse generator longevity among new and refurbished pacemakers with P = 0.681. There was no infection and device malfunction in the 3 months. Conclusion: The reused pacemaker batteries are safe and do no increased risk of infection and malfunction. This provides an effective option for patients who cannot afford a new device or a replacement battery.

Longevity of Implantable Pulse Generators in Bilateral Deep Brain Stimulation for Movement Disorders

Longevity of Implantable Pulse Generators in Bilateral Deep Brain Stimulation for Movement Disorders

Longevity of Implantable Pulse Generators in Bilateral Deep Brain Stimulation for Movement Disorders

Deep brain stimulation (DBS) is a well-established therapy for otherwise intractable movement disorders. Thus far, most patients receive nonrechargeable implantable pulse generators (IPG). Eventually, another intervention to replace the IPG is inevitable. We assessed IPG model-specific differences in longevity in patients planned for IPG replacement. Also, we evaluated the influence of the total electric energy delivered (TEED), the amount of previous IPG replacements, and previous IPG model changes on the longevity. We collected the demographic data and DBS settings of 47 patients (19 with Parkinson's disease, 7 with essential tremor, and 21 with dystonia) that were treated either with Medtronic's Kinetra® (N = 16) or Activa® PC (N = 31). Statistical analysis was performed using Mann-Whitney U test and Spearman's rank correlation. Battery longevity was shorter in the Activa PC than in the Kinetra (40.16 ± 15.22 vs. 70.35 ± 24.45 months; p < 0.001). Further analysis showed an inverse correlation of the longevity to TEED (r = -0.529; p < 0.001) and the number of previous IPG replacements (r = -0.588; p < 0.001). Furthermore, patients with more frequent replacements had higher TEED (r = 0.501; p < 0.001) and patients, whose Kinetra was replaced with the Activa PC before, had shorter IPG longevity (28.36 ± 9.82 vs. 45.78 ± 14.19 months; p = 0.006). Our findings imply that IPG longevity is shorter in the Activa PC compared to the Kinetra. Higher TEED and more frequent IPG replacements might reduce IPG longevity.

An exploratory propensity score matched comparison of second-generation and first-generation baroreflex activation therapy systems

Baroreflex activation therapy (BAT) is a device-based therapy for patients with treatment-resistant hypertension. In a randomized, controlled trial, the first-generation system significantly reduced blood pressure (BP) versus sham. Although an open-label validation study of the second-generation system demonstrated similar BP reductions, controlled data are not presently available. Therefore, this investigation compares results of first- and second-generation BAT systems. Two cohorts of first-generation BAT system patients were generated with propensity matching to compare against the validation group of 30 second-generation subjects. The first cohort was drawn from the first-generation randomized trial sham group and the second cohort from the active therapy group. Safety and efficacy were compared for the second-generation group relative to the first generation. At 6 months, second-generation BAT outperformed first-generation sham systolic BP reduction by 20 ± 28 mm Hg (mean ± standard deviation, P = .008), while BP reduction in first- and second-generation active groups was similar. At 12 months, efficacy was comparable between all three groups after the sham group had received 6 months of therapy; 47% of second-generation patients achieved goal systolic BP of 140 mm Hg or less after 12 months, comparable to 50% of patients at goal in the first-generation group (P > .999). Implant procedure time, system/procedural safety, and pulse generator longevity improved with the second-generation system. Propensity-matched cohort analysis of the first- and second-generation BAT systems suggests similar therapeutic benefit and superior BP reduction of the second-generation system relative to sham control. Implantation procedure duration and perioperative safety were improved with the second-generation device. These findings should be validated in a prospective randomized trial.

Deep Brain Stimulation Battery Longevity: Comparison of Monopolar Versus Bipolar Stimulation Modes.

Deep brain stimulation is an effective treatment for movement disorders, but it is relatively complex, invasive, and costly. Little is known about whether stimulation mode alters pulse generator (battery) longevity in routine clinical care. To compare battery longevity during monopolar versus bipolar stimulation in patients who underwent deep brain stimulation for movement disorders. We evaluated 2,902 programming adjustments and calculated the average stimulator settings for 393 batteries in 200 unique patients with Parkinson's disease and essential tremor. We classified the pulse generators into different stimulation modes (monopolar, bipolar, tripolar, double monopolar) and compared battery longevity with Kaplan Meier survival analyses using the log rank test. We exclusively implanted the Medtronic 3387 lead with adjacent electrode contacts separated by 1.5 mm. The mean pulse generator longevity was 47.6±1.6 months regardless of diagnosis or stimulation mode. Bipolar stimulation mode was associated with greater longevity than monopolar stimulation (56.1±3.4 versus 44.2±2.1 months, p=0.006). This effect was most pronounced when stimulation parameters were at low to moderate intensity settings. Double monopolar configuration was associated with less pulse generator longevity than conventional stimulation modes (37.8±5.6 versus 49.7±1.9, p=0.014). IPGs initially programmed in bipolar mode provided one year of additional battery longevity versus monopolar mode in this large retrospective series of patients with essential tremor and Parkinson's disease. Given satisfactory efficacy for motor symptoms, bipolar stimulation mode is a feasible alternative programming strategy at the initiation of DBS therapy.

Shorter Pulse Generator Longevity and More Frequent Stimulator Adjustments With Pallidal DBS for Dystonia Versus Other Movement Disorders

Deep brain stimulation has become a routine therapy for movement disorders, but it is relatively invasive and costly. Although stimulation intensity relates to battery longevity, less is known about how diagnosis and stimulation target contribute to this clinical outcome. Here we evaluate battery longevity in movement disorders patients who were treated at a tertiary referral center. To compare single channel pulse generator longevity in patients with movement disorders. With Institutional Review Board approval, we evaluated 470 consecutive Soletra implants for routine care. Battery longevity was estimated with Kaplan-Meier analyses, and group comparisons were performed with the log rank mean test. The frequency of clinic encounters for ongoing care was evaluated across diagnoses with analysis of variance (ANOVA). The mean pulse generator longevity was 44.9±1.4 months. Pallidal DBS for dystonia was associated with shorter battery longevity than subthalamic and thalamic DBS for Parkinson's disease and essential tremor (28.1±2.1 versus 47.1±1.8 and 47.8±2.6 months, respectively, mean±standard error, P<0.001), and dystonia patients required more frequent clinic visits for routine care (F=6.0, P=0.003). Pallidal DBS for Parkinson's disease and thalamic DBS for cerebellar outflow tremor were associated with shorter battery longevity, as well (35.3±4.6 and 26.4±4.3 months, respectively). Pallidal DBS for dystonia was associated with shorter battery longevity and more frequent stimulator adjustments versus DBS for Parkinson's disease and essential tremor. Characteristics of the stimulation target and disease pathophysiology both likely contribute to battery longevity in patients with movement disorders.

The Implantable Cardioverter-Defibrillator Minimalist

The implantable cardioverter-defibrillator (ICD) was devised to satisfy the unmet need for an effective, instantaneous therapy to prevent sudden cardiac death (SCD) due to ventricular fibrillation (VF) in at-risk, ambulatory patients. That therapy was a high-voltage electric shock delivered directly into the heart muscle. More than 3 decades later, shocks are still the defining operating characteristic of ICDs, and no other instantaneously effective therapy for VF exists. This elite status was clinched by large randomized clinical trials1,2 which demonstrated that ICDs improved mortality in patients with reduced left ventricular ejection fraction, regardless of pathogenesis or accompanying symptoms of heart failure (HF), by primary prevention of SCD due to ventricular tachyarrhythmia (VTA). Like bradycardia pacemakers for asystole, the ICD resides as a therapy genre of one, with no peer, and no competitor on the horizon. These sibling therapies for lethal heart rhythm disturbances will stand prominently among the greatest medical achievements of the 20th century. The ICD is a mature technology, and neither the technique nor the tools have changed much for several decades. Despite a certain evolutionary elegance of the operating system, the ICD is still a blunt instrument. Although it is true that some innovation has occurred, it is still a matter of a shock delivered by insulated metal conductors residing somewhere in direct proximity to the heart. No innovation beyond the fundamental of a timed shock for VF has proven to enhance mortality benefit. The basic design persists simply because no one can think of a suitable alternative and the self-satisfying aphorism that “shocks save lives.” Yet there is a growing intellectual dissatisfaction with the unintended consequences of this powerful, irreplaceable therapy. The stimulus for this self-inspection is an awareness of the very high morbidity risk overhead borne by the primary prevention patient, in particular, …

The reality of implantable cardioverter-defibrillator longevity: What can be done to improve cost-effectiveness?

r a o v s p Multiple clinical trials have demonstrated the mortality benefit of implantable cardioverter-defibrillator (ICD) therapy for the primary prevention of sudden cardiac death, expanding the indications for device therapy. However, ICDs are expensive and patient longevity often exceeds pulse generator longevity, so many patients will require replacement of pulse generators, which is associated with additional costs. Generator replacement also carries a substantial risk for complications even when performed electively. While the overall risk of initial implantation complicaions is 3.2% in the National Cardiovascular Data Registry ICD egistry, the risk of major complications for generator replaceents is 4.1%–5.8%, with complications including death. Risks are even higher for patients undergoing system upgrade, and risks of pocket-related adverse events requiring surgical intervention increase with every consecutive replacement. Therefore, it is eneficial to reduce the need for upgrade or replacement of pulse enerators. In the current issue of HeartRhythm, Thijssen et al assess the ongevity of 4673 ICDs implanted since 1996, identifying that 2% were replaced because of battery depletion. Overall, the ean device longevity was only 5.0 0.1 years and slightly onger at 5.5 0.1 years for devices replaced because of battery depletion.

Prediction of Implantable Pulse Generator Longevity in Deep Brain Stimulation: Limitations and Possible Solutions in Clinical Practice

Background: Deep brain stimulation (DBS) is used in the treatment of movement disorders, chronic pain and certain neuropsychiatric conditions. Its effect is achieved through local stimulation of specific targets of the brain. Electrical pulses are delivered at settings that can be tailored to provide optimum symptom control. DBS is powered by an implantable pulse generator (IPG). These IPGs do not have an indefinite lifespan and will eventually become depleted. Therefore, regular checks are carried out to monitor the IPG’s power status. Objective: To evaluate the utility of computer-based prediction of IPG longevity in patients with DBS devices by imputing the device’s settings. Patients: Eighty-two IPGs in 47 consecutive patients were studied comparing the actual longevity of the IPGs with their predicted longevity using a computer-based calculator. Results: Our study showed that the predicted longevities were too different from actual longevities to have a role in clinical practice. The time difference varied by more than 12 months in some cases, with a correlation coefficient of <0.68. There were multiple reasons for this. Conclusion: The longevities of IPGs could not be predicted accurately enough for the computer-based calculator to have a role in clinical practice or the proactive scheduling of IPG replacement. However, rechargeable IPGs may help avoid premature replacements and battery depletions.

Impact of automatic threshold capture on pulse generator longevity

The automatic, threshold tracking, pacing algorithm developed by St. Jude Medical, verifies ventricular capture beat by beat by recognizing the evoked response following each pacemaker stimulus. This function was assumed to be not only energy saving but safe. This study estimated the extension in longevity obtained by AutoCapture (AC) compared with pacemakers programmed to manually optimized, nominal output. Thirty-four patients who received the St. Jude Affinity series pacemaker were included in the study. The following measurements were taken: stimulation and sensing threshold, impedance of leads, evoked response and polarization signals by 3501 programmer during followup, battery current and battery impedance under different conditions. For longevity comparison, ventricular output was programmed under three different conditions: (1) AC on; (2) AC off with nominal output, and (3) AC off with pacing output set at twice the pacing threshold with a minimum of 2.0 V. Patients were divided into two groups: chronic threshold is higher or lower than 1 V. The efficacy of AC was evaluated. Current drain in the AC on group, AC off with optimized programming or nominal output was (14.33 +/- 2.84) mA, (16.74 +/- 2.75) mA and (18.4 +/- 2.44) mA, respectively (AC on or AC off with optimized programming vs. nominal output, P < 0.01). Estimated longevity was significantly extended by AC on when compared with nominal setting [(103 +/- 27) months, (80 +/- 24) months, P < 0.01). Furthermore, compared with the optimized programming, AC extends the longevity when the pacing threshold is higher than 1 V. AC could significantly prolong pacemaker longevity; especially in the patient with high pacing threshold.

P2-2: Outcomes of six monthly stimulation threshold assessments in patients with pacing systems: A twentieth year follow-up

The purpose of this review was to evaluate the yield of atrial & ventricular stimulation threshold (ST) assessments at each routine six month pacemaker clinic (PC) visit. Since n 1983, and as reported in 1995, six monthly ST have been performed in all 886 actively followed pts: 73.34 ± 0.27 (range 16-102 yrs) with programmable output pacing systems (PS) to establish reduced output levels for safe capture margins while maintaining pulse generator longevity. All records of pts with PS implanted for greater than 24 months were retrospectively reviewed for ST stability.

13.6 Longevity and failure modes of ICD pulse generators: results from the International Multicenter Registry

13.6 Longevity and failure modes of ICD pulse generators: results from the International Multicenter Registry

13.6 Longevity and failure modes of ICD pulse generators: results from the International Multicenter Registry

13.6 Longevity and failure modes of ICD pulse generators: results from the International Multicenter Registry

13.6 Longevity and failure modes of ICD pulse generators: Results from the international multicenter registry

13.6 Longevity and failure modes of ICD pulse generators: Results from the international multicenter registry

Effect of modern pacing algorithms on generator longevity: a predictive analysis.

Pulse generator (PG) longevity is of major importance to the quality of care of pacemaker patients. A series of automatic algorithms affect PG longevity. This study investigated the individual and combined effects of three algorithms incorporated in the Medtronic Kappa 700 pacemaker series: Capture Management periodically measures the stimulation threshold and adjusts the PG output, Sinus Preference allows the sinus rate to prevail in a specified range below the sensor rate, and Search AV allows an extension of the AV interval if spontaneous conduction is observed. The effects of Capture Management, Sinus Preference, and Search AV on device longevity were studied in 21 consecutive patients treated in the VDD and DDDR modes. Patients were followed for 1 year. The data were analyzed using an equation provided by the manufacturer. Capture Management was activated in 20 patients. For 11 PGs at the basic settings, longevity was extended by 5.2%, whereas reprogrammed PGs had no gain. Sinus Preference was active in four DDDR patients, who gained 12.0 +/- 5.3%atrial sensing from it, with a resultant longevity gain of1.4 +/- 0.45 months(NS). Search AV was active in 19 patients and 8 responders gained 7.8 +/- 4.4 months PG longevity. The overall longevity in this study was 106.3 +/- 8.4 months with all features as programmed, whereas the longevity without Capture Management and Search AV algorithms would be 98.2 +/- 4.9 months, saving 8.1 +/- 5.8 months(range 0-18) of battery life. Thus, two algorithms: Capture Management and Search AV, have clinical relevance in the extension of PG longevity.

Long-term experience with a preshaped left ventricular pacing lead.

This study describes a long-term experience with a new LV pacing lead. The study population consisted of 62 patients (85% men, 71 +/- 10 years old) with advanced dilated cardiomyopathy, in NYHA Class III or IV despite optimal drug therapy, and a QRS duration > 150 ms. Patients in sinus rhythm were implanted with a triple chamber pacemaker to maintain atrioventricular synchrony. A dual chamber pacemaker was implanted in patients in atrial fibrillation for biventricular pacing only. A clinical evaluation and interrogation of the resynchronization pacemaker were performed at implant, at 1 week (W1), one (M1), four (M4), and seven (M7) months after implantation. A longer follow-up (2 years) is available for patients implanted at the authors institution. LV measurements were pacing threshold at 0.5-ms pulse duration and pacing impedance. R wave amplitude (mV) was measured at the time of implantation only. The system was successfully implanted in 86% of patients with the latest design of the lead. Mean R wave amplitude at implant was 15 +/- 7 mV and mean pacing impedance was 1054 +/- 254 omega. Between implant (n = 38) and M7 (n = 15), pacing threshold rose from 0.73 +/- 0.54 to 1.57 +/- 0.60 V (P < 0.001). In conclusion, the situs lead was successfully implanted in a high percentage of patients. In addition, low pacing threshold and high impedance measured during follow-up are consistent with a low pacing current drain, ensuring a durable pulse generator longevity.

Influence of pacing parameters on pacemaker longevity

This study retrospectively assessed the parameters that affect pulse generator longevity in 78 patients implanted with dual-chamber pacemakers. Longevity was studied in 52 generators: 14 Cosmos II, 17 Relay, 11 Ellite II, and 10 Thera DR. The lifetimes of Cosmos II and Ellite II were significantly prolonged compared to those of Relay and Thera DR. The comparative study was conducted to evaluate the effect of low-impedance leads (ThinLine I, n = 10) on generator longevity compared with a standard lead (Irox, n = 16). No significant variation in pacing threshold was found between the groups. However, the low-impedance group provided significantly lower cell voltage and higher cell impedance during all follow-up periods compared with the standard lead impedance group. The internal current of the pacemaker with rate response and sophisticated diagnostic memory function (Relay, n = 5, and Marathon DR, n = 5) increased significantly compared with the conventional pacemaker (Cosmos II, n = 5). In conclusion, the selection of unnecessary pacing parameters and the selection of low-impedance leads should be avoided in order to extend generator longevity.

The impact of automatic threshold tracking on pulse generator longevity in patients with different chronic stimulation thresholds.

Automatic adjustment of the stimulation output of pacemakers to changing stimulation thresholds using the Autocapture feature increases patient safety and decreases energy consumption. This study examined the impact of Autocapture on pulse generator longevity in patients with different chronic stimulation thresholds. Eighty patients (mean age 79 +/- 9 years; 37 men, 43 women) with Pacesetter Regency SR+ pacemakers were included in the study. Data were collected before discharge of the patients from the hospital, 6-12 weeks postimplant, and then every 6-12 months. Pulse generator longevity was calculated theoretically, assuming 100% stimulation with a stable threshold, at a pacing rate of 65 +/- 6 beats/min and 1% backup pulses. Theoretical pulse generator longevity was calculated for low (< 1 V), intermediate (> or = 1 V and < 2 V), and high (> or = 2 V) stimulation thresholds. Pulse generator longevity was compared among three groups: (A) Autocapture programmed On, (B) Autocapture programmed Off, (C) theoretical calculations using thresholds of patients in group A with the stimulation voltage programmed at twice pacing threshold, or at a minimum of 2.4 V. The mean follow-up time since implantation was 19 +/- 8 months. The calculated longevity benefits for patients in group A were 36%, 59%, and 30% compared to group B, and 19%, 32%, and 49% compared to group C in patients with low, intermediate, and high chronic stimulation thresholds, respectively. Theoretical calculations based on chronic stimulation thresholds in our patient population with Regency SR+ pacemakers suggest that Autocapture may markedly prolong pulse generator longevity in patients with a broad range of long-term pacing thresholds.

ICD THERAPY IN THE NEW MILLENNIUM

Remarkable progress has been made in the 15 years since ICD therapy was approved for human use. The early "shock boxes" had almost no diagnostic capabilities and required thoracotomy for epicardial patch implantation with typical duration of hospitalization of about a week. Pulse-generator longevity was less than 2 years. Modern devices provide detailed information about the morphology and rate of electrocardiographic signals before, during, and after arrhythmia therapy. The down-sizing of pulse generators and improvements in lead design and shock waveforms allow the simplicity of defibrillator implantation to approach that of pacemakers, with defibrillation thresholds comparable with those initially observed with epicardial patches. Despite the marked reduction in size and increase in diagnostic capabilities, device longevity is now longer than 6 years. Routine outpatient ICD implantation is presently feasible and will increase in frequency if ongoing primary prevention trials prove beneficial. Further advances in lead technology and arrhythmia discrimination should increase the efficacy and reliability of therapy. Finally, devices have the capabilities to treat multiple problems in addition to life-threatening ventricular arrhythmias including atrial arrhythmias and congestive heart failure.

Automatic capture verification by charge-neutral sensing.

Automatic capture verification can prolong pulse generator longevity and increase patient safety. However, the detection of evoked response following pacing is complicated due to afterpotentials caused by polarization of electrodes. This study describes a new capture verification scheme, which neutralizes the charges between the pacing electrodes. The hypothesis of the charge-neutral sensing is that the afterpotentials in the ring and the tip are opposite in polarity when pacing in a bipolar mode between ring and tip. Summing the unipolar signals sensed at the tip and the ring should effectively cancel the afterpotentials. This scheme was implemented in an external computer based system and tested during pacemaker implant/replacement on 23 patients during VVI pacing (17 acutely implanted leads and 6 chronic leads). Surface ECG was recorded to provide a marker for capture and noncapture. The pacing voltage was gradually decreased until a noncapture beat was noted. To avoid fusion beats, the pacing rate was programmed approximately 50% higher than the intrinsic rate. The evoked response was high pass filtered and the integral average was calculated for both capture and noncapture beats. The system signal to noise ratio (SNR) was expressed as ratio of the minimum integral average of all capture beats to the maximum integral average of all noncapture beats. The system SNR was 8.6 +/- 1.3 (mean +/- S.E.M; range 1.5-22.8), indicating that the charge-neutral sensing method has, on average, a ninefold safety margin in providing capture verification. Further, evaluation is needed to fully assess this feature in patients with chronic leads.