Risk factors for lead complications in cardiac pacing: a population-based cohort study of 28,860 Danish patients

[Treatment with cardiac electronic implantable devices]

Cardiac device therapy provides not only treatment options for bradyarrhythmia but also advanced treatment for heart failure and preventive measures against sudden cardiac death. In heart failure treatment it enables synergistic reverse remodelling and reduces pharmacological side effects. Cardiac resynchronization therapy (CRT) has revolutionized the treatment of reduced left ventricular ejection fraction (LVEF) and left bundle branch block by decreasing the mortality and morbidity with improvement of the quality of life and resilience. Conduction system pacing (CSP) as an alternative method of physiological stimulation can improve heart function and reduce the risk of pacemaker-induced cardiomyopathy. Leadless pacers and subcutaneous/extravascular defibrillators offer less invasive options with lower complication rates. The prevention of infections through preoperative and postoperative strategies enhances the safety of these therapies.

Prophylactic epicardial pacemaker implantation in tricuspid valve replacement

OBJECTIVES

Patients undergoing surgical tricuspid valve replacement (TVR) are at high risk of atrioventricular conduction disorders. Because implanting a lead through the tricuspid bioprosthesis is discouraged, the patients who undergo TVR in our centre are usually given a prophylactic epicardial pacemaker. Our aim was to assess the benefits and risks of this strategy.

METHODS

Among the patients who underwent TVR with prophylactic epicardial pacemaker implantation, clinical evaluations and pacemaker reports were analysed retrospectively after surgery. The need for cardiac pacing were assessed by characterizing the atrioventricular conduction, while the risks were evaluated by listing and adjudicating post-operative events.

RESULTS

A total of 80 patients were analysed (mean age was 57 ± 16 years old, 30% males). TVR was isolated in 28 (35%) patients, but most often associated with another valve surgery. In the postoperative period, heart rhythm was analysed in 59/80 patients during a median follow-up of 35 months. Cardiac pacing was needed in 46% patients: 14% had complete pacing dependency, 17% had high degree AV block, while 15% had a high ventricular pacing rate (>80%). No pre- or per-operative variables could predict cardiac pacing requirement. Post-operatively, a spontaneous heart rate >70 bpm (P = 0.02) and the presence of narrow QRS (P = 0.03) were significantly associated with a lower risk of cardiac pacing requirement. Complications related to epicardial pacemaker were documented in 2 (2.5%) patients.

CONCLUSIONS

After TVR, cardiac pacing was needed in 46% of patients for post-operative atrioventricular conduction disorders. This high incidence associated with an acceptable safety profile supports a prophylactic epicardial pacing strategy for the patients undergoing TVR.

Analysis of prescription medication rules of traditional Chinese medicine for bradyarrhythmia treatment based on data mining

BACKGROUND

Multiple studies have revealed that Traditional Chinese Medicine (TCM) prescriptions can provide protective effect on the cardiovascular system, increase the heart rate and relieve the symptoms of patients with bradyarrhythmia. In China, the TCM treatment of bradyarrhythmia is very common, which is also an effective complementary therapy. In order to further understand the application of Chinese medicines in bradyarrhythmia, we analyzed the medication rules of TCM prescriptions for bradyarrhythmia by data mining methods based on previous clinical studies.

METHODS

We searched studies reporting the clinical effect of TCM on bradyarrhythmia in the PubMed and Chinese databases China National Knowledge Infrastructure database, and estimated publication bias by risk of bias tools ROB 2. Descriptive analysis, hierarchical clustering analysis and association rule analysis based on Apriori algorithm were carried out by Microsoft Excel, SPSS Modeler, SPSS Statistics and Rstidio, respectively. Association rules, co-occurrence and clustering among Chinese medicines were found.

RESULTS

A total of 48 studies were included in our study. Among the total 99 kinds of Chinese medicines, 22 high-frequency herbs were included. Four new prescriptions were obtained by hierarchical cluster analysis. 81 association rules were found based on association rule analysis, and a core prescription was intuitively based on the grouping matrix of the top 15 association rules (based on confidence level), of which Guizhi, Zhigancao, Wuweizi, Chuanxiong, Danshen, Danggui, Huangqi, Maidong, Dangshen, Rougui were the most strongly correlated herbs and in the core position.

CONCLUSION

In this study, data mining strategy was applied to explore the TCM prescription for the treatment of bradyarrhythmia, and high-frequency herbs and core prescription were found. The core prescription was in line with the treatment ideas of TCM for bradyarrhythmia, which could intervene the disease from different aspects and adjust the patient's Qi, blood, Yin and Yang, so as to achieve the purpose of treatment.

Device-related complications in subcutaneous versus transvenous ICD: a secondary analysis of the PRAETORIAN trial

BACKGROUND

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial.

METHODS AND RESULTS

The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047).

CONCLUSION

This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice.

Case report: A rare complication after the implantation of a cardiac implantable electronic device: Contralateral pneumothorax with pneumopericardium and pneumomediastinum

Cardiac implantable electronic devices (CIED) including pacemakers (PM), implantable cardioverter defibrillators (ICD), and cardiac resynchronized therapy (CRT) have become the mainstay of therapy for many cardiac conditions, consequently drawing attention to the risks and benefits of these procedures. Although CIED implantation is usually a safe procedure, pneumothorax remains an important complication and may contribute to increased morbidity, mortality, length of stay, and hospital costs. On the other hand, pneumopericardium and pneumomediastinum are rare but potentially fatal complications. Accordingly, a high degree of awareness about these complications is important. Pneumothorax almost always occurs on the ipsilateral side of implantation. The development of contralateral pneumothorax is uncommon and may be undetected on an initial chest radiograph. Contralateral pneumothorax with concurrent pneumopericardium and pneumomediastinum is much rarer. We describe a rare case of concurrent right-sided pneumothorax with pneumopericardium and pneumomediastinum after left-sided pacemaker implantation and highlight the risk factors, management, and possible ways to prevent the complications.

Impact of socioeconomic aspects on cardiac implantable electronic device treatment and application of the EHRA guidelines : A European comparison

BACKGROUND

Cardiac implantable electronic devices (CIED) have become an indispensable part in everyday clinical practice in cardiology. The indications for CIED implantation are based on the guidelines of the European Heart Rhythm Association (EHRA). Nevertheless, numbers of CIED implantations in Europe are subject to considerable differences. We hypothesized that reimbursements linked to the respective health systems may influence implantation behavior.

METHODS

Based on the EHRA White Book 2017, CIED implantation data as well as socioeconomic key figures were collected, in particular gross domestic product (GDP) and share of gross domestic product spent on healthcare. Implantation numbers for pacemakers, implantable cardioverter defibrillators and cardiac resynchronization treatment as well as all in total were assessed, compared with the health care expenditures and visualized using heat maps.

RESULTS

Total implantation numbers per 100,000 inhabitants varied from 196.53 (Germany) to 2.81 (Kosovo). Higher implantation numbers correlated moderately with a higher GDP (r = 0.456, p 0.002) and higher health expenditure (r = 0.586, p < 0.001). The annual financial resources per inhabitant were also subject to fluctuations ranging from 9476 $ (Switzerland) to 140 $ (Ukraine); however, there were countries with high financial means, such as Switzerland or Scandinavian countries, which showed significantly lower implantation rates.

CONCLUSION

There were considerable differences in CIED implantations in Europe. These seem to be explained in part by socioeconomic disparities within Europe. Also, a potential influence by the respective remuneration system is likely.

Lead complications after cardiac surgery in patients with cardiac implantable electronic devices

OBJECTIVES

Manipulation of the heart during cardiac surgery in patients with cardiac implantable electronic devices may result in lead damage or -displacement, but whether cardiac surgery truly infers an excess risk of lead failure is not known. The objective of this study was to examine risk of lead complications after cardiac surgery in patients with cardiac implantable electronic devices.

METHODS AND RESULTS

We conducted a nationwide nested case-control study. The source population comprised all Danish patients ≥18 of age who underwent a de novo cardiac implantable electronic device implantation during 1998-2017. For inclusion, patients had to be alive and event-free 6 months after implantation. Cases were matched 1:30 to controls on time, age, sex and device type using risk set sampling. We used conditional logistic regression to estimate incidence rate ratios (IRRs) for the association between cardiac surgery and lead-related reoperation.

RESULTS

Our final population consisted of 67,621 patients. We identified 1437 (2.1%) incident cases of lead-related reoperations and 42,698 controls. Risk of lead complications was highest within six months of cardiac surgery (IRR 9.7, 95% CI 6.3-14.8, adjusted IRR 9.6, 95% CI 6.2-14.7), and at one year, the relative risk of lead-related reoperation was close to unity (adjusted IRR 1.2, 95% CI 0.8-1.7).

CONCLUSION

Cardiac surgery was associated with a considerable risk of lead complications in patients with de novo cardiac implantable electronic devices.

Canadian Heart Rhythm Society Task Force Report on Physician Training and Maintenance of Competency for Cardiovascular Implantable Electronic Device Therapies: Executive Summary

Physicians engaged in cardiovascular implantable electronic device (CIED)-related practice come from diverse training backgrounds with variable degrees of CIED implant training. The objective of the Canadian Heart Rhythm Society Task Force on CIED Implant Training was to establish a common structure and content for training programs in CIED implantation, related activities and maintenance of competency. This executive summary presents the essence of the report with key recommendations included, with the complete version made available in a linked supplement. The goals are to ensure that future generations of CIED implanters are better prepared for continuously evolving CIED practice and quality care for all Canadians.

Single-Pass VDD Pacing Lead for Cardiac Resynchronization Therapy: A Reliable Alternative

(1) Background: Cardiac resynchronization therapy (CRT) systems can be simplified by excluding the atrial lead and using a Ventricular-Dual-Dual (VDD) pacing lead. Possible disadvantages might include atrial undersensing and Ventricular-Ventricular-Inhibition (VVI) pacing. Because literature data concerning these systems are scarce, we analyzed their benefits and technical safety. (2) Methods: this retrospective study compared 50 patients implanted with VDD–CRT systems (group A), mainly because of unfavorable venous anatomy concerning the complication rate, with 103 subjects with Dual-Dual-Dual (DDD)–CRT systems (group B) implanted during 2000–2016 and 49 (group C) during 2016–2020. To analyze the functional parameters of the devices, we selected subgroups of 27 patients (subgroup A) and 47 (subgroup B) patients with VDD–CRT in 2000–2016, and 36 subjects (subgroup C) with DDD–CRT implanted were selected in 2017–2020. (3) Results: There was a trend of a lower complication rate with VDD–CRT systems, especially concerning infections during 2000–2016 (p = 0.0048), but similar results were obtained after rigorous selection of patients and employment of an upgraded design of devices/leads. With a proper device programing, CRT pacing had similar results, atrial undersensing being minimal (p = 0.65). For VDD-systems, VVI pacing was recorded only 1.7 ± 2.24% of the time. (4) Conclusions: In patients with a less favorable venous anatomy, VDD–CRT systems may represent a safe alternative regarding complications rates and functional parameters.

Avoiding implant complications in cardiac implantable electronic devices: what works?

Nearly one in ten patients experience complications in relation to cardiac implantable electronic device (CIED) implantations. CIED complications have serious implications for the patients and for the healthcare system. In light of the rising rates of new implants and consistent rate of complications, primary prevention remains a major concern. To guide future efforts, we sought to review the evidence base underlying common preventive actions made during a primary CIED implantation.

Device infections related to cardiac resynchronization therapy in clinical practice-An analysis of its prevalence, risk factors and routine surveillance at a single center university hospital

Background

The implantation rates of cardiac implantable electronic devices have steadily increased, accompanied by a steeper rise of device related infections (DRI).

Hypothesis

The prevalence of DRI for cardiac resynchronization therapy (CRT) is higher in clinical practice than reported previously, even at a university hospital, and likely higher than reported to the national device registry.

Methods

Electronic medical records of consecutive patients undergoing a CRT procedure between January 2016 and December 2017 were analyzed. Clinical history, procedure related variables and complications were reviewed by specialists in cardiology and infectious diseases.

Results

A total of 171 patients, mean aged 74 years, 138 males (80.7%) were included. Twelve DRI occurred in 10 patients during mean 2.5 years follow‐up, giving a prevalence of 7% (incidence of 29/1000 person‐years). Reoperation, pocket haematoma, ≥3 procedures, previous device infection and indwelling central venous line were the strongest predictive factors according to univariate analysis. Out of 63/171 (36.8%) major complications, 31(49.2%) were lead‐related. There were 49/171 (28.7%) reoperations and 15/171 (8.8%) minor complications. The number major complications and DRI reported to the national device registry were 7/171 (4.1%) and 2/171 (0.6%), respectively, reflecting a 5‐fold underreporting.

Conclusions

The high rate of CRT device infections is in sharp contrast to those reported by others and to the national device registry. Although a center specific explanation cannot be excluded, the high rates highlight a major issue with registries, reinforcing the need for better surveillance and automatic reporting of device related complications.

Driving following defibrillator implantation: a nationwide register-linked survey study

AIMS

Patients are restricted from driving following implantable cardioverter defibrillator (ICD) implantation or shock. We sought to investigate how many patients are aware of, and adhere to, the driving restrictions, and what proportion experience an ICD shock or other cardiac symptoms while driving.

METHODS AND RESULTS

We performed a nationwide survey of all living Danish residents 18 years or older who received a first-time ICD between 2013 and 2016 (n = 3913) and linked their responses with nationwide registers. Of 2741 respondents (47% primary prevention, 83% male, median age 67 years), 2513 (92%) held a valid driver's license at ICD implantation, 175 (7%) of whom had a license for professional driving. Many drivers were unaware of driving restrictions: primary prevention 58%; secondary prevention 36%; post-appropriate shock 28%; professional drivers 55%. Almost all (94%) resumed non-professional driving after ICD implantation, more than one-third during the restricted period; 35% resumed professional driving. During a median follow-up of 2.3 years, 5 (0.2%) reported receiving an ICD shock while driving, one of which resulted in a traffic accident. The estimated risk of harm was 0.0002% per person-year.

CONCLUSION

In this nationwide study, many ICD patients were unaware of driving restrictions, and more than one third resumed driving during a driving restriction period. However, the rate of reported ICD shocks while driving was very low.

Cardiac Contractility Modulation in Patients with Heart Failure with Reduced Left Ventricular Ejection Fraction

Cardiac contractility modulation is an innovative therapy conceived for the treatment of heart failure. It is a device-based therapy, employing multiple electrodes to deliver relatively high-voltage (~7.5 V) biphasic signals to the endocardium of the right ventricular septum, in order to improve heart failure symptoms, exercise capacity and quality of life. Multiple clinical and mechanistic studies have been conducted to investigate the potential usefulness of this technology and, as of now, they suggest that it could have a place in therapy and meet a relevant medical need for a specific sub-category of underserved heart failure patients with reduced left ventricular ejection fraction. More studies are needed to further investigate its effect on outcomes such as mortality and rate of hospitalizations.

Long-Term Technical Performance of the Osypka QT-5® Ventricular Pacemaker Lead

Background: Lead-associated complications and technical issues in patients with cardiac implantable electronic devices are common but underreported in the literature. Methods: All patients undergoing implantation of the Osypka QT-5^® ventricular lead at the University Clinic St. Pölten between 1 January 2006 and 31 December 2012 were retrospectively analyzed (n = 211). Clinical data including pacemaker follow-up examinations and the need for lead revisions were assessed. Kaplan–Meier analysis to estimate the rate of lead dysfunction during long-term follow-up was conducted. Results: Patients were followed for a median of 5.2 years (interquartile range (IQR) 2.0–8.7). R-wave sensing properties at implantation, compared to last follow-up, remained basically unchanged: 9.9 mV (IQR 6.8–13.4) and 9.6 mV (IQR 5.6–12.0), respectively). Ventricular pacing threshold significantly increased between implantation (0.5 V at 0.4 ms; IQR 0.5–0.8) and the first follow-up visit (1.0 V at 0.4 ms; IQR 0.8–1.3; p < 0.001) and this increase persisted throughout to the last check-up (0.9 V at 0.4 ms; IQR 0.8–1.2). Impedance significantly declined from 1142 Ω (IQR 955–1285) at implantation to 814 Ω (IQR 701–949; p < 0.001) at the first check-up, followed by a further decrease to 450 Ω (IQR 289–652; p < 0.001) at the last check-up. Overall, the Osypka QT-5^® ventricular lead was replaced in 36 patients (17.1%). Conclusions: This report shows an unexpected high rate of technical issues of the Osypka QT-5^® ventricular lead during long-term follow-up.

Assessing safety of leadless pacemaker (MICRA) at various implantation sites and its impact on paced QRS in Indian population

Background

In this study we report our experience in implanting MICRA TPS (transcatheter pacing system) at various RV sites; observing its safety, and impact on paced QRS in Indian population.

Material & methods

35 patients with MICRA TPS deployed from March 2017 to December 2019 at Army Hospital Research and Referral, New Delhi, at RVOT, apical septum and mid septum of RV were enrolled in the study. These patents were followed up and impact of implantation site, procedure related complications, change in pacing parameters, left ventricular ejection fraction and duration of paced QRS were monitored.

Results

Sick sinus syndrome was the commonest indication of pacing in this study (51.5%), followed by high degree AV block (34.2%). Mean follow up of 1.4 years showed no change in left ventricular ejection fraction, electrical parameters or change in pacing thresholds after implantation. Mean pQRS was broadest (166.60 ms) in apically implanted MICRA TPS and narrowest in mid septum group 139.33 ms. Among 35 cases, in our study one patient developed pericardial effusion, and other had intermittent diaphragmatic pacing.

Conclusion

Among these three implantation sites mid septum deployment is associated with narrowest paced QRS in Indian population.

Novel bradycardia pacing strategies

The adverse effects of ventricular dyssynchrony induced by right ventricular (RV) pacing has led to alternative pacing strategies, such as biventricular, His bundle (HBP), LV septal (LVSP) and left bundle branch pacing (LBBP). Given the overlap, LVSP and LBBP are also collectively referred to as left bundle branch area pacing (LBBAP). Although among these alternative pacing sites HBP is theoretically the ideal strategy as it maintains a physiological ventricular activation, its application requires more skills and is associated with the most complications. LBBAP, where the ventricular pacing lead is advanced through the interventricular septum to its left side, creates ventricular activation that is only slightly more dyssynchronous. Preliminary studies have shown that LBBAP is feasible, safe and encounters less limitations than HBP. Further studies are needed to differentiate between LVSP and LBBP with regard to acute functional and long-term clinical outcome.

Cardiac contractility modulation for the treatment of heart failure with reduced ejection fraction

There has been a progressive evolution in the management of patients with chronic heart failure and reduced ejection fraction (HFrEF), including cardiac resynchronisation therapy (CRT) in those that fulfil pre-defined criteria. However, there exists a significant proportion with refractory symptoms in whom CRT devices are not clinically indicated or ineffective. Cardiac contractility modulation (CCM) is a novel therapy that incorporates administration of non-excitatory electrical impulses to the interventricular septum during the absolute refractory period. Implantation is analogous to a traditional transvenous pacemaker system, but with the use of two right ventricular leads. Mechanistic studies have shown augmentation of left ventricular contractility and beneficial global effects on reverse remodeling, primarily through alterations in calcium handling. This appears to occur without increasing myocardial oxygen consumption. Data from clinical trials have shown translational improvements in functional capacity and quality of life, though long-term outcome data are lacking. This review explores the rationale, evidence base and limitations of this nascent technology.

Wide Frequency Characterization of Intra-Body Communication for Leadless Pacemakers

Leadless Cardiac Pacemakers (LCP) have the potential to revolutionize Cardiac Rhythm Management (CRM). Current LCPs can only pace a single location of the heart limiting their use to patients requiring single-chamber stimulation. A Multi-node system of synchronized LCPs could be used in a significantly larger patient population. Synchronization using standard communication techniques involves high power consumption decreasing the longevity of the device. In this work, we investigate Galvanic Intra Body Communication (IBC) as a method to synchronize multi-node LCP systems. First, an accurate computational torso model was used for quasi-static simulations to estimate channel pathloss in the frequency range [40 kHz-20 MHz]. The model was then verified with in-vivo measurements using a novel experimental setup, where two LCP devices were placed in the right atrium, right ventricle and left ventricle. All channels involved in a potential multi-node LCP system were characterized. The orientation of the transducers relative to each other had a great impact on the results, with the attenuation level ranging between 55 dB and 70 dB between the best and worst orientations. The best results were achieved in the MHz range. Coupled with the fact that it does not require additional electrodes, this study suggests Galvanic IBC be superior to conventional communication methods for LCP devices. This analysis defines a methodology for galvanic IBC channel characterization for LCP systems, which is an important step for the design of efficient transceivers for IBC applications. More experiments with larger datasets are needed to bring this method to practice.

Complications and associated healthcare costs of transvenous cardiac pacemakers in Germany

Aim: This study evaluated the occurrence and associated costs of pacemaker complications in Germany from 2010 to 2013. Patients & methods: Patients with a de novo or replacement implantation of a single or dual chamber pacemaker between 2010 and 2013 were followed for 12 months post-implant using German health insurance claims data. A case-control analysis was performed using propensity score matching to estimate the costs of complications. Results: Out of 12,922 implanted patients, 12.0% had a complication in the year following the implant. Complications related to lead and pocket were found in 10.2% of all implanted patients; infections occurred in 1.7% patients. Healthcare costs up to 36 months post complication were on average €4627 higher than for pacemaker patients without a complication. Conclusion: Pacemaker complications are common and represent a burden for patients and healthcare systems generating substantial costs. Most of the pacemaker complications involved the pacing lead or pacemaker pocket.

Active periodic electrograms in remote monitoring of pacemaker recipients: the PREMS study

AIMS

Remote monitoring (RM) is considered as a standard of care for pacemaker recipients. Remote monitoring systems provide calendar-based intracardiac electrogram recordings (IEGM) only with the current pacemaker settings (passive IEGM). PREMS (Pacemaker Remote Electrogram Monitoring Study), an observational, multicentre trial, prospectively evaluated the clinical value of an active IEGM (aIEGM), including three 10-s sections (passive IEGM, encouraged sensing, and encouraged pacing), compared to other RM data and to its passive IEGM section. Secondary objectives included the added value of the aIEGM to fully assess the sensing and pacing functions of each lead.

METHODS AND RESULTS

Patients were enrolled within 3 months after pacemaker implantation and followed until the first transmitted aIEGM, which was analysed together with all other RM data. In total, 567 patients were enrolled (79 ± 9 years, 62% men, 19% single-chamber, and 81% dual-chamber pacemakers). Of 547 aIEGMs transmitted in 547 patients, 161 [29.4%; 95% confidence interval (95% CI) 25.6-33.3%] indicated at least one anomaly non-detectable with certainty-or at all-on other RM data, including atrial arrhythmia, extrasystoles, undersensing, oversensing, and loss of capture. In 21.7% of cases the detected events deserved a corrective action. The sensing and pacing function of each lead could be fully assessed in 77.3% of aIEGM (95% CI 72.6-82.0%) vs. 15.5% (95% CI 11.4-19.6%) when considering only the passive IEGM section (P < 0.001).

CONCLUSION

An active IEGM improves the clinical value of remote pacemaker follow-up. Furthermore, compared to a passive IEGM, the aIEGM increases the capability to fully assess remotely the sensing and pacing functions.

Leadless multisite pacing: A feasibility study using wireless power transfer based on Langendorff rodent heart models

INTRODUCTION

Fifteen to thirty percent of patients with impaired cardiac function have ventricular dyssynchrony and warrant cardiac resynchronization therapy (CRT). While leadless pacemakers eliminate lead-related complications, their current form factor is limited to single-chamber pacing. In this study, we demonstrate the feasibility of multisite, simultaneous pacing using miniaturized pacing nodes powered through wireless power transfer (WPT).

METHODS

A wireless energy transfer system was developed based on resonant coupling at approximately 200 MHz to power multiple pacing nodes. The pacing node comprises circuitry to efficiently convert the harvested energy to output stimuli. To validate the use of these pacing nodes, ex vivo studies were carried out on Langendorff rodent heart models (n = 4). To mimic biventricular pacing, two beating Langendorff rodent heart models, kept 10 cm apart, were paced using two distinct pacing nodes, each attached on the ventricular epicardial surface of a given heart.

RESULTS

All ex vivo Langendorff heart models were successfully paced with a simple coil antenna at 2 to 3 cm from the pacing node. The coil was operated at 198 MHz and 0.3 W. Subsequently, simultaneous pacing of two Langendorff heart models 30 cm apart using an output power of 5 W was reliably demonstrated.

CONCLUSION

WPT provides a feasible option for multisite, wireless cardiac pacing. While the current system remains limited in design, it offers support and a conceptual framework for future iterations and eventual clinical utility.

Leadless pacing

Leadless self-contained intracardiac pacemakers were developed with the aim of abolishing the short- and long-term risk of lead- and pocket-related complications associated with transvenous devices. Leadless pacemakers promise minimally invasive procedures, long battery lives, and small amounts of foreign materials in the body. Experiences with the pioneering single-chamber devices have provided reasons for optimism about the future of the leadless concept. In the future, as more patients receive and live longer with implantable devices, the total risk of procedure- and lead-related complications is expected to increase, adding a sense of urgency to the need for leadless alternatives to transvenous pacemakers. This review surveys the performance of currently available leadless pacemakers as well as emerging new innovative adaptations and applications of the leadless concept.

Living with a pacemaker: patient-reported outcome of a pacemaker system

Background

The aim of this study was to assess among pacemaker patients their overall satisfaction with the pacemaker system, pain, soreness/discomfort, cosmetic results, restrictions due to impaired movement of the shoulder/arm/chest, related sleep disturbances, and concern about possible device malfunction.

Methods

The seven-item questionnaire was mailed to patients from a single center who had a pacemaker implant or replacement between 2006 and 2016. A higher score indicated worse outcome on a visual analog scale (VAS) of 0–100 mm.

Results

The response rate was 75.5% and 342 questionniares were analyzed. Median age of respondents was 77.6 years and 57.0% were males. In total, 65 complications requiring surgery (10 pocket corrections (2.9%), 5 in females) occurred during a median follow-up of 5.6 years.The distribution of the primary outcome had a median score of 5 while the 75th percentile was 13. Cosmetic appearance was significantly associated with reoperation (but not other variables). Overall scores for men and women were 5 vs. 6, respectively, which achieved significance (p = 0.042). Median ratings of pain, soreness/discomfort, cosmetic appearance, range of motion, sleep, and concern about device malfunction were all ≤5. Females reported worse outcomes for all questions, except for cosmetic results and concern about malfunction.

Conclusions

The vast majority of patients report excellent overall satisfaction with the pacemaker system, and are not affected by pain, soreness/discomfort, or concern about device malfunction. They also reported favourable outcomes with respect to cosmetic results, shoulder movement, and sleep. However, some patients underwent a surgical correction of the pacemaker pocket.

Long-term results of combined cardiac contractility modulation and subcutaneous defibrillator therapy in patients with heart failure and reduced ejection fraction

BACKGROUND

Cardiac contractility modulation (CCM) is an electrical-device therapy for patients with heart failure with reduced ejection fraction (HFrEF). Patients with left ventricular ejection fraction (LVEF) ≤35% also have indication for an implantable cardioverter-defibrillator (ICD), and in some cases subcutaneous ICD (S-ICD) is selected.

HYPOTHESIS

CCM and S-ICD can be combined to work efficaciously and safely.

METHODS

We report on 20 patients with HFrEF and LVEF ≤35% who received CCM and S-ICD. To exclude device interference, patients received intraoperative crosstalk testing, S-ICD testing, and bicycle exercise testing while CCM was activated. Clinical and QOL measures before CCM activation and at last follow-up were analyzed. S-ICD performance was evaluated while both CCM and S-ICD were active.

RESULTS

Mean follow-up was 34.3 months. NYHA class improved from 2.9 ± 0.4 to 2.1 ± 0.7 (P < 0.0001), Minnesota Living With Heart Failure Questionnaire score improved from 50.2 ± 23.7 to 29.6 ± 22.8 points (P < 0.0001), and LVEF improved from 24.4% ± 8.1% to 30.9% ± 9.6% (P = 0.002). Mean follow-up time with both devices active was 22 months. Three patients experienced a total of 6 episodes of sustained ventricular tachycardia, all successfully treated with first ICD shock. One case received an inappropriate shock unrelated to the concomitant CCM. One patient received an LVAD, so CCM and S-ICD were discontinued.

CONCLUSIONS

CCM and S-ICD can be successfully combined in patients with HFrEF. S-ICD and CCM remain efficacious when used together, with no interference affecting their function.

Impact of intraoperative mechanical ventilation on left ventricular lead function in cardiac resynchronization therapy

BACKGROUND

Intraoperative controlled mechanical ventilation (CMV) changes the intrathoracic geometry and may impact postoperative left ventricular (LV) lead function after CRT implantation. This multicenter study investigates the effect of intraoperative ventilation setting (spontaneous breathing [SB] vs CMV) on postoperative LV lead function taking into account patients' body mass index (BMI).

METHODS

CRT implantation was performed at two centers during SB in 92 and during CMV in 73 patients. Follow-up was carried out after 3 ± 5 and 36 ± 53 days. Functional lead parameters (FLP; pacing threshold and impedance), postoperative adverse events (A;  phrenic nerve stimulation [PNS] and lead malfunction), and patients' BMI were assessed. Delta values of FLP between baseline and follow-up visits were analyzed applying an analysis of covariance model to detect subclinical alterations in LV lead function.

RESULTS

AE occurred in a total of 36 (21%) patients. PNS was observed in 26 (15%) patients and LV lead repositioning due to malfunction was necessary in 10 (6%) patients. Both AE and FLP delta values between baseline and follow-up were not associated with intraoperative ventilation settings nor the patients' BMI.

CONCLUSIONS

This study demonstrates that there is no impact of the intraoperative ventilation setting (SB vs CMV) on postoperative FLP or the occurrence of AE. This is also the case taking into account the BMI. With respect to these findings both approaches-sedation only or general anaesthesia including CMV-can be safely implemented during CRT implantation.

Placement Of Cardiac PacemaKEr Trial (POCKET) - rationale and design: a randomized controlled trial

Background

A pacemaker system consists of one or two leads connected to a device that is implanted into a pocket formed just below the collarbone. This pocket is typically subcutaneous, that is, located just above the pectoral fascia. Even though the size of pacemakers has decreased markedly, complications due to superficial implants do occur. An alternative technique would be intramuscular placement of the pacemaker device, but there are no randomized controlled trials (RCTs) to support this approach, which is the rationale for the Placement Of Cardiac PacemaKEr Trial (POCKET). The aim is to study if intramuscular is superior to subcutaneous placement of a pacemaker pocket.

Methods

In October 2016, we started to enroll 200 consecutive patients with an indication for bradycardia pacemaker implantation. Patients are randomized to random block sizes, stratified by age group (cut-off: 65 years) and sex, and then randomized to either subcutaneous or intramuscular implant. A concealed allocation procedure is employed, using sequentially numbered, sealed envelopes. Pocket site is blinded to the patient and in all subsequent care. The primary endpoint is patient overall satisfaction with the pocket location at 24 months as measured using a visual analog scale (VAS) 0-10. Secondary endpoints are: complications, patient-reported satisfaction at 1, 12, and 24 months (overall satisfaction, pain, discomfort, degree of unsightly appearance, movement problems, and sleep problems due to device).

Conclusions

POCKET is a prospective interventional RCT designed to evaluate if intramuscular is superior to subcutaneous placement of a bradycardia pacemaker during a two-year follow-up.

Incidence, predictors, and outcomes associated with pneumothorax during cardiac electronic device implantation: A 16-year review in over 3.7 million patients

BACKGROUND

Pneumothorax (PTX) is a potential complication of vascular access during cardiac implantable electronic device (CIED) procedures and is being scrutinized as a health care-acquired condition.

OBJECTIVE

The purpose of this study was to determine the trends in PTX incidence in the United Stated over a 16-year period and to determine whether PTX is associated with increased mortality after adjustment for other factors.

METHODS

Using weighted sampling in the largest inpatient health database in the United States (National Inpatient Sample), we evaluated data from patients with a primary procedure of CIED implantation from 1998 to 2013 who had at least 1 new vascular access (new or upgrade of prior CIED). The unadjusted and adjusted associations of PTX with mortality and other parameters were examined.

RESULTS

Among 3,764,703 CIED procedures, PTX occurred in 47,839 cases (1.3%). The apparent incidence of PTX peaked at 1.6% in 2012 and 2013, although this result may have been affected by a concomitant decrease of inpatient (vs outpatient) CIED. PTX was significantly associated with pulmonary complications, chest tube insertion, length of stay, and costs. Mortality was statistically higher in patients with PTX (1.2% vs 0.7%; P <.001), a relationship that remained significant in a multivariate logistic regression analysis (odds ratio 1.50, 95% confidence interval 1.36-1.65; P <.001). Age >80 years, female gender, Caucasian race, chronic obstructive pulmonary disease, and dual-chamber (vs single-chamber) device were all associated with higher odds for PTX occurrence. Placement of a chest tube was a major determinant of worse outcomes and higher costs.

CONCLUSION

PTX remains an important complication of CIED procedures and is associated with increased morbidity, mortality, and costs.

Is mortality a useful parameter for public reporting in pacemaker implantation? Results of an obligatory external quality control programme

AIMS

To evaluate if public reporting of pacemaker implantation-associated mortality is meaningful in a large contemporary patient cohort.

METHODS AND RESULTS

The database of the obligatory external quality control programme in the Federal State of Hessen, Germany, of patients undergoing permanent pacemaker (PPM) implantation was evaluated retrospectively. We compared the baseline features of patients who died compared with those who did not during hospitalization after PPM. Of 5079 patients who underwent PPM implantation in 2009, 74 (1.5%) died during the hospital stay. Cause of death was available in 70/74 patients (94.6%) who died. Deceased patients were older (79.6 ± 8.7 vs. 76.3 ± 9.9 years, P = 0.006), had worse American Society of Anesthesiologists (ASA) physical status (P < 0.001), lower ejection fraction (P < 0.001), a greater prevalence of high-degree atrioventricular-block (44.3 vs. 35.0%, P = 0.001), and were more likely to receive single-chamber devices (41.4 vs. 25.0%, P < 0.002). Perioperative complications were similar in both cohorts. Death was not attributable directly to PPM procedure in any patients but was related to (i) non-device-related infections (28.6%), (ii) heart failure (25.7%), (iii) extracardiac diseases (21.4%), (iv) multiorgan failure (8.6%), (v) previous resuscitation with hypoxic brain damage (8.6%), and (vi) arrhythmogenic death (7.1%).

CONCLUSION

Mortality associated with PPM implantation in vast majority of cases was not related to the procedure, but to comorbidities and other existing diseases at the time of PPM implantation. Thus, PPM implantation in-hospital mortality should not be chosen for public reporting comparing hospital quality, even after adjusting for baseline risk.

The impact of co-morbidity burden on appropriate implantable cardioverter defibrillator therapy and all-cause mortality: insight from Danish nationwide clinical registers

AIMS

In a nationwide cohort of primary (PP-ICD) and secondary prevention (SP-ICD) implantable cardioverter defibrillator (ICD) patients, we aimed to investigate the association between co-morbidity burden and risk of appropriate ICD therapy and mortality.

METHODS AND RESULTS

We identified all patients >18 years, implanted with first-time PP-ICD (n = 1873) or SP-ICD (n = 2461) in Denmark from 2007 to 2012. Co-morbidity was identified in administrative registers of hospitalization and drug prescription from pharmacies. Co-morbidity burden was defined as the number of pre-existing non-ICD indication-related co-morbidities including atrial fibrillation, diabetes, chronic obstructive pulmonary disease, chronic renal disease, liver disease, cancer, chronic psychiatric disease, and peripheral and/or cerebrovascular disease, and divided into four groups (co-morbidity burden 0, 1, 2, and ≥3). Through Cox models, we assessed the impact of co-morbidity burden on appropriate ICD therapy and mortality. Increasing co-morbidity burden was not associated with increased risk of appropriate therapy, irrespective of implant indication [all hazard ratios (HRs) 1.0-1.4, P = NS]. Using no co-morbidities as reference, increasing co-morbidity burden was associated with increased mortality risk in PP-ICD patients (co-morbidity burden 1, HR 2.1; comorbidity burden 2, HR 3.7; co-morbidity burden ≥3, HR 6.6) (all P < 0.001) and SP-ICD patients (co-morbidity burden 1, HR 2.2; co-morbidity burden 2, HR 3.8; co-morbidity burden ≥3, HR 5.8). With increasing co-morbidity burden, an increasing frequency of patients died without having utilized their device, with 72% PP-ICD and 45% SP-ICD patients with co-morbidity burden ≥3 dying without prior appropriate ICD therapy.

CONCLUSION

Increasing co-morbidity burden was not associated with increased risk of appropriate ICD therapy. With increasing co-morbidity burden, mortality increased, and a higher proportion of patients died, without ever having utilized their device.

Management of Cardiac Electronic Device Infections: Challenges and Outcomes

Cardiac implantable electronic device (CIED) infection is an increasing problem. Reasons for this are uncertain, but likely relate to an increasing proportion of implantable cardioverter defibrillator (ICD) and cardiac resynchronisation therapy (CRT) devices implanted, as well as implantations in 'higher risk' candidates, i.e. patients with heart failure, diabetes and renal failure. Challenges within the field of CIED infections are multiple with prevention being the most important challenge. Careful prescription of CIED treatment and careful patient preparation before implantation is important. Diagnosis is often difficult and delayed by subtle signs of infection. Treatment of CIED infection includes complete system removal in centres experienced in CIED extraction and prolonged antibiotic therapy. Meticulous planning and preparation before system extraction and later CIED re-implantation is essential for better patient outcome. Future strategies for reducing CIED infection should be tested in sufficiently powered, multicentre, randomised controlled trials.

Procedural Success of Left Ventricular Lead Placement for Cardiac Resynchronization Therapy: A Meta-Analysis

OBJECTIVES

The goal of this study was to assess the contemporary and historical success rates of transvenous left ventricular (LV) lead placement for cardiac resynchronization therapy (CRT), their change over time, and the reasons for failure.

BACKGROUND

In selected patients, CRT improves morbidity and mortality, but the placement of the LV lead can be technically challenging.

METHODS

A literature search was used to identify all studies reporting success rates of LV lead placement for CRT via the coronary sinus (CS) route. A total of 164 studies were identified, and a meta-analysis was performed.

RESULTS

The studies included 29,503 patients: 74% (95% confidence interval [CI]: 72% to 76%) were male; their mean age was 66 years (95% CI: 65 to 67); their mean New York Heart Association functional class was 2.8 (95% CI: 2.7 to 2.9); the mean LV ejection fraction was 26% (95% CI: 25% to 28%); and the mean QRS duration was 155 ms (95% CI: 150 to 160). The overall rate of failure of implantation of an LV lead was 3.6% (95% CI: 3.1 to 4.3). The rate of failure in studies commencing before 2005 was 5.4% (95% CI: 4.4% to 6.5%), and from 2005 onward it was 2.4% (95% CI: 1.9% to 3.1%; p < 0.001). Causes of failure (reported for 39% of failures) also changed over time. Failure to cannulate and navigate the CS decreased from 53% to 30% (p = 0.01), and the absence of any suitable, acceptable vein increased from 39% to 64% (p = 0.007). The proportion of leads in a lateral or posterolateral final position (reported for 26% of leads) increased from 66% to 82% (p = 0.004).

CONCLUSIONS

The reported rate of failure to place an LV lead via the CS has decreased steadily over time. A greater proportion of failures in recent studies are due to coronary venous anatomy that is unsuitable for this technique.

Design and In Vivo Test of a Batteryless and Fully Wireless Implantable Asynchronous Pacing System

Goal: The aim of this study is to develop a novel fully wireless and batteryless technology for cardiac pacing.

METHODS

This technology uses radio frequency (RF) energy to power the implanted electrode in the heart. An implantable electrode antenna was designed for 1.2 GHz; then, it was tested in vitro and, subsequently, integrated with the rectifier and pacing circuit to make a complete electrode. The prototype implanted electrode was tested in vivo in an ovine subject, implanting it on the epicardial surface of the left ventricle. The RF energy, however, was transmitted to the implanted electrode using a horn antenna positioned 25 cm above the thorax of the sheep.

RESULTS

It was demonstrated that a small implanted electrode can capture and harvest enough safe recommended RF energy to achieve pacing. Electrocardiogram signals were recorded during the experiments, which demonstrated asynchronous pacing achieved at three different rates.

CONCLUSION

These results show that the proposed method has a great potential to be used for stimulating the heart and provides pacing, without requiring any leads or batteries. It hence has the advantage of potentially lasting indefinitely and may never require replacement during the life of the patient.

SIGNIFICANCE

The proposed method brings forward transformational possibilities in wireless cardiac pacing, and also in powering up the implantable devices.

Minimally invasive thoracoscopic technique for cardiac resynchronization therapy

Outcome of surgical left ventricular (LV) lead placement is not well defined in patients with failed percutaneous cardiac resynchronization therapy. An extended experience with epicardial LV lead placement is here reported, describing the minimally invasive procedure performed at our institution using a thoracoscopic surgical approach.