Pacemaker lead infection in young patients

Transient pacing in pigs with complete heart block via myocardial injection of mRNA coding for the T-box transcription factor 18

The adenovirus-mediated somatic transfer of the embryonic T-box transcription factor 18 (TBX18) gene can convert chamber cardiomyocytes into induced pacemaker cells. However, the translation of therapeutic TBX18-induced cardiac pacing faces safety challenges. Here we show that the myocardial expression of synthetic TBX18 mRNA in animals generates de novo pacing and limits innate and inflammatory immune responses. In rats, intramyocardially injected mRNA remained localized, whereas direct myocardial injection of an adenovirus carrying a reporter gene resulted in diffuse expression and in substantial spillover to the liver, spleen and lungs. Transient expression of TBX18 mRNA in rats led to de novo automaticity and pacemaker properties and, compared with the injection of adenovirus, to substantial reductions in the expression of inflammatory genes and in activated macrophage populations. In rodent and clinically relevant porcine models of complete heart block, intramyocardially injected TBX18 mRNA provided rate-adaptive cardiac pacing for one month that strongly correlated with the animal's sinus rhythm and physical activity. TBX18 mRNA may aid the development of biological pacemakers.

New Guidelines of Pediatric Cardiac Implantable Electronic Devices: What Is Changing in Clinical Practice?

Guidelines are important tools to guide the diagnosis and treatment of patients to improve the decision-making process of health professionals. They are periodically updated according to new evidence. Four new Guidelines in 2021, 2022 and 2023 referred to pediatric pacing and defibrillation. There are some relevant changes in permanent pacing. In patients with atrioventricular block, the heart rate limit in which pacemaker implantation is recommended was decreased to reduce too-early device implantation. However, it was underlined that the heart rate criterion is not absolute, as signs or symptoms of hemodynamically not tolerated bradycardia may even occur at higher rates. In sinus node dysfunction, symptomatic bradycardia is the most relevant recommendation for pacing. Physiological pacing is increasingly used and recommended when the amount of ventricular pacing is presumed to be high. New recommendations suggest that loop recorders may guide the management of inherited arrhythmia syndromes and may be useful for severe but not frequent palpitations. Regarding defibrillator implantation, the main changes are in primary prevention recommendations. In hypertrophic cardiomyopathy, pediatric risk calculators have been included in the Guidelines. In dilated cardiomyopathy, due to the rarity of sudden cardiac death in pediatric age, low ejection fraction criteria were demoted to class II. In long QT syndrome, new criteria included severely prolonged QTc with different limits according to genotype, and some specific mutations. In arrhythmogenic cardiomyopathy, hemodynamically tolerated ventricular tachycardia and arrhythmic syncope were downgraded to class II recommendation. In conclusion, these new Guidelines aim to assess all aspects of cardiac implantable electronic devices and improve treatment strategies.

Transvenous Lead Extraction in Adult Patient with Leads Implanted in Childhood-Is That the Same Procedure as in Other Adult Patients?

BACKGROUND

Lead management in children and young adults is still a matter of debate.

METHODS

To assess the course of transvenous lead extraction (TLE) in adults with pacemakers implanted in childhood (CIP) we compared 98 CIP patients with a control group consisting of adults with pacemakers implanted in adulthood (AIP).

RESULTS

CIP patients differed from AIP patients with respect to indications for TLE and pacing history. CIP patients were four-eight times more likely to require second-line or advanced tools. Furthermore, CIP patients more often than AIP were prone to developing complications: major complications (MC) (any) 2.6 times; hemopericardium 3.2 times; severe tricuspid valve damage 4.4 times; need for rescue cardiac surgery 3.7 times. The rate of procedural success was 11% lower because of 4.8 times more common lead remnants and 3.1 times more frequent permanently disabling complications.

CONCLUSIONS

Due to system-related risk factors TLE in CIP patients is more difficult and complex. TLE in CIP is associated with an increased risk of MC and incomplete lead removal. A conservative strategy of lead management, acceptable in very old patients seems to be less suitable in CIP because it creates a subpopulation of patients at high risk of major complications during TLE in the future.

Effect of fibrotic capsule debridement during generator replacement on cardiac implantable electronic device infection risk

BACKGROUND

Cardiovascular implantable electronic device (CIED) replacement is increasingly common. It has been proposed that capsule removal at the time of CIED replacement may reduce infection rates. In this study, we aimed to assess how pocket capsule removal impacted infection rates in patients undergoing CIED replacement.

METHODS

We retrospectively reviewed the medical records of patients who underwent CIED replacement from 2006 to 2016 at a single centre. We retrieved patient data, procedure details, and clinical outcomes. To evaluate the relationship between capsule removal and CIED infection, we used the Cox proportional hazard model, with adjustment for multiple variables.

RESULTS

During the study period, 773 patients underwent device replacement. Of these patients, 194 (25%) underwent capsule debridement during the replacement procedure. The mean patient age was 75 ± 15 years, and 281 (36.3%) were females. The replaced CIEDs included DDD pacemakers (32%), VDD pacemakers (15%), VVI/AAI pacemakers (13%), defibrillators (22%), and cardiac resynchronization therapy devices (CRT-D/P) (17%). During an average follow-up of 3.6 years, 42 (5%) patients experienced a CIED infection. Multivariate analysis revealed that patients who underwent capsule removal had a significantly lower risk of CIED infection, with a hazard ratio of 0.32 (95% confidence interval, 0.12-0.83; P = 0.019).

CONCLUSIONS

Capsule debridement during CIED replacement was associated with a significant reduction of CIED infection risk. There is a need for randomized controlled studies to confirm these findings.

A Minimally Invasive Approach for Placing Sew-On Epicardial Leads in the Child

Traditionally, pacing leads are placed transvenously, although smaller pediatric patients who require permanent pacemakers may benefit from delaying tranvenous lead placement until they are larger. Alternative, minimally invasive atrioventricular pacing options have not previously existed for this patient population, leaving many of these children with large sternotomies or thoracotomies. Using three port sites and an adjustable shaft dual-needle suturing device, we placed a steroid-eluting, sew-on epicardial lead on the right atrium of a 9-year-old patient. This is one of the earliest reported cases of a minimally invasive technique for sew-on epicardial lead placement on the atrium of a child. Although based on a single case, we believe that this approach is safe, reliable, and reproducible and that it can be used to place leads on any aspect of the heart. Adoption of this technique will allow for earlier atrioventricular pacing, which may decrease the incidence of pacemaker syndrome, and thus improve overall outcomes in this patient population.

Antibiotic Prophylaxis Practices in Pediatric Cardiac Implantable Electronic Device Procedures: A Survey of the Pediatric And Congenital Electrophysiology Society (PACES)

Cardiac implantable electronic device (CIED) infections are associated with significant morbidity in the pediatric device population, with a tenfold higher risk of infection in children compared to adults. The 2010 American Heart Association (AHA) guidelines recommend a single dose of systemic antibiotic (ABX) prophylaxis prior to CIED implantation and no post-operative (OP) ABX. However, there is limited data regarding adherence to this recommendation among the pediatric community. To assess current clinical practices for CIED ABX prophylaxis in pediatrics; whether the AHA guidelines are being followed; and if not, the reasons for non-adherence. An anonymous web-based survey was sent to physician members of the Pediatric And Congenital Electrophysiology Society regarding ABX prophylaxis for new CIED implants and reoperations. 75 (25%) members responded. Only 7% of respondents follow the 2010 AHA guidelines. While all respondents give pre-OP IV ABX, 64% routinely treat patients with 24-h post-OP IV ABX with additional oral or IV therapy. 69% of respondents are cognizant of the guidelines but 88% of those cognizant do not follow the guidelines for a variety of reasons including lack of data and different substrate (pediatric patients). 79% stated that pediatric-specific data would be required for them to change their practice and follow the published guidelines. The majority of pediatric EP physicians who responded to this survey do not follow the current AHA guidelines on ABX prophylaxis and administer post-OP ABX. Most pediatric EP physicians believe that the increased risk of infection in children merits additional ABX.

Overcoming the current issues surrounding device leads: reducing the complications during extraction

INTRODUCTION

The implantation rate of cardiac implantable electronic devices has consistently increased in the last 20 years, as have the related complication rates. The most relevant issue is the removal of pacing and implantable cardioverter defibrillator (ICD) leads, which a few months after implantation tend to develop intravascular fibrosis, often making extraction a challenging and risky procedure. Areas covered: The transvenous lead extraction (TLE) scenario is constantly evolving. TLE is a key procedure in lead management strategies. Many efforts have been made to develop new TLE approaches and techniques allowing a safe and effective procedure for patients. The increasing rate of cardiac implantable electronic device (CIED) implantations and of CIED related complications highlight the importance of TLE. Lead related- and patient-related factors may change the future of extractions. We review the current status of TLE, focusing on the strategies available to perform the optimal procedure in the right patient and reducing procedure related complications. Expert commentary: Understanding the importance of an accurate TLE risk stratification is mandatory to optimize the procedural risk-to-benefits ratio. The use of adequate tools, techniques and approaches, and appropriate training are cornerstones for the achievement of safer procedures.

Lead extraction outcomes in patients with congenital heart disease

Aims

Patients with congenital heart disease (CHD) are at increased risk for intracardiac device malfunction and infection that may necessitate extraction; however, the risk of extraction is poorly understood. This study addresses the safety of extraction in patients with structural heart disease and previous cardiac surgery.

Methods and results

This retrospective study included 40 CHD and 80 matched control patients, who underwent transvenous lead extractions between 2001 and 2014. Only leads >12 months were included. There were 77 leads in CHD patients and 146 in controls. The mean age was 38 ± 16 years in CHD patients. Ninety per cent of CHD patients had ≥1 cardiac surgeries when compared with 21% of controls (P < 0.001). The number of abandoned leads was significantly different (17 vs. 3, P < 0.001). Lead age was similar with an average duration of 83 ± 87 months in CHD patients and 62 ± 65 months in controls (P = 0.24). There was no significant difference in extraction techniques. Manual traction was successful in 40% of CHD patients and 47% of controls, and advanced techniques were used in 60 and 53% of CHD patients and controls, respectively. Complete extraction was achieved in 94% of the patients in both groups. There was no significant difference in complications.

Conclusion

Lead extraction can be safely performed in patients with CHD. Despite anatomic abnormalities and longer implantation times, the difficulty of lead extraction in patients with CHD is comparable with controls.

Prevention, Diagnosis, and Treatment of Cardiac Implantable Electronic Device Infections

Cardiac implantable electronic device (CIED) infections are complex medical problems that are increasingly encountered. They are associated with significant morbidity and mortality with tremendous economic cost. The current review will emphasize the prevention, diagnosis, and treatment of this clinical entity using the relatively limited evidence that is currently available. Because there is a paucity of high quality evidence regarding prevention, diagnosis, and treatment of CIED infections, this review will attempt to summarize the best evidence as well as to suggest, when possible, paradigms for care. The topic of CIED infections is a dynamic one as the scope of CIED continues to widen. Furthermore, there are promising advancements in CIED technology which may help reduce its occurrence the future. Unfortunately, significant gaps in knowledge remain, and definitive recommendations regarding CIED infections and future studies should be directed at improving our ability to prevent infections.

Identification of bacteriology and risk factor analysis of asymptomatic bacterial colonization in pacemaker replacement patients

Background

Recent researches revealed that asymptomatic bacterial colonization on PMs might be ubiquitous and increase the risk of clinical PM infection. Early diagnosis of patients with asymptomatic bacterial colonization could provide opportunity for targeted preventive measures.

Objective

The present study explores the incidence of bacterial colonization of generator pockets in pacemaker replacement patients without signs of infection, and to analyze risk factors for asymptomatic bacterial colonization.

Methods

From June 2011 to December 2013, 118 patients underwent pacemaker replacement or upgrade. Identification of bacteria was carried out by bacterial culture and 16S rRNA sequencing. Clinical risk characteristics were analyzed.

Results

The total bacterial positive rate was 37.3% (44 cases), and the coagulase-negative Staphylococcus aureus detection rate was the highest. Twenty two (18.6%) patients had positive bacterial culture results, of which 50% had coagulase-negative staphylococcus. The bacterial DNA detection rate was 36.4 % (43 cases). Positive bacterial DNA results from pocket tissues and the surface of the devices were 22.0% and 29.7%, respectively. During follow-up (median, 27.0 months), three patients (6.8%, 3/44) became symptomatic with the same genus of microorganism, S. aureus (n=2) and S. epidermidis (n=1). Multivariable logistic regression analysis showed that history of bacterial infection, use of antibiotics, application of antiplatelet drugs, replacement frequency were independent risk factors for asymptomatic bacterial colonization.

Conclusion

There was a high incidence of asymptomatic bacterial colonization in pacemaker patients with independent risk factors. Bacterial culture combined genetic testing could improve the detection rate.

Genetic identification and risk factor analysis of asymptomatic bacterial colonization on cardiovascular implantable electronic devices

Asymptomatic bacterial colonization of cardiovascular implantable electronic devices (CIEDs) is widespread and increases the risk of clinical CIED infection. The aim of the study was to evaluate the incidence of bacterial colonization of generator pockets in patients without signs of infection and to analyze the relationship with clinical infection and risk factors. From June 2011 to December 2012, 78 patients underwent CIED replacement or upgrade. Exclusion criteria included a clinical diagnosis of CIED infection, bacteremia, or infective endocarditis. All patients were examined for evidence of bacterial 16S rDNA on the device and in the surrounding tissues. Infection cases were recorded during follow-up. The bacterial-positive rate was 38.5% (30 cases); the coagulase-negative Staphylococcus detection rate was the highest (9 cases, 11.5%). Positive bacterial DNA results were obtained from pocket tissue in 23.1% of patients (18 cases), and bacterial DNA was detected on the device in 29.5% of patients (23 cases). During follow-up (median 24.6 months), two patients (6.7%, 2/30) became symptomatic with the same species of microorganism, S. aureus and S. epidermidis. Multivariable logistic regression analysis found that the history of bacterial infection, use of antibiotics, application of antiplatelet drugs, replacement frequency, and renal insufficiency were independent risk factors for asymptomatic bacterial colonization.

Cardiac pacing in paediatric patients with congenital heart defects: transvenous or epicardial?

AIMS

Cardiac pacing is a difficult technique in children, particularly in patients with congenital heart defects (CHDs). Few studies to date have addressed this topic.

METHODS AND RESULTS

We performed a retrospective analysis of the results of a single centre. Between 1982 and 2008, 287 patients with CHD, median age of 5 years (25-75%, 1-11) underwent cardiac pacing for sinus node dysfunction (SND) and atrioventricular block (AVB); 97% of patients underwent at least one heart surgery. Endocardial systems (Endo) were implanted in 117 patients, epicardial systems (Epi) in 170, with 595 leads (228 Endo, 367 Epi). Endocardial systems showed a significantly older age group with more frequent SND; Epi a younger age group, with more frequent AVB, greater number of surgical interventions. Perioperative complications were mortality 0.6% (Epi), pericardial effusion 0.6% (Epi), and haemothorax 3.4% (Endo). The median follow-up is 5 (2-10) years: the pacing system failed in 29% of patients, 13% Endo, and 40% Epi (P < 0.0001). Multivariate analysis showed a significantly higher risk of failure for Epi, a lower implant age, greater the number of leads implanted. The risk of malfunction of the leads increases significantly for Epi and the younger age when implanted. The steroid-eluting leads have a lower risk of malfunction (P = 0.05), steroid-eluting Endo leads provide significantly better outcomes than Epi.

CONCLUSION

Cardiac pacing in paediatric patients with CHD shows satisfactory results in the long term. Endocardial systems show significantly better results than Epi systems. A younger age when implanted is a risk factor for complications at follow-up.

Pacing device therapy in infants and children: a review

The number of pediatric pacemakers implanted is still relatively small. Children requiring pacing therapy have characteristics that are distinct from those of adults, including physical size, somatic growth, and cardiac anomalies. Considering these features, long-term follow-up of pediatric pacemaker implantation is necessary. Selection of appropriate generators, pacing modes, pacing sites, and leads is important. Generally, epicardial leads are commonly used in small infants. On the other hand, the use of endocardial leads in children is increasing worldwide because of their benefits over epicardial leads, such as minimal invasiveness, lower pacing threshold, and longer generator longevity. Endocardial leads are not suitable for patients with intracardiac shunts because of the high risk of systemic thrombosis. Venous occlusion is another significant problem with endocardial leads. With the increase in the number of pacing device implantations, the incidence of infection from such devices is also increasing. Complete device removal is sometimes recommended to treat device infection, but experience in the removal of endocardial leads in children is still scarce. This article gives an overview of pacing therapy in the pediatric population, including discussions on new pacing systems, such as remote monitoring systems, magnetic imaging compliant pacemaker systems, and leadless pacing devices.

Clinical experience of entirely subcutaneous implantable cardioverter-defibrillators in children and adults: cause for caution

AIMS

This paper describes our clinical experience of using an entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) in children and adults. Maintaining lead integrity and long-term vascular access are critical challenges of ICD therapy, especially in younger patients. The S-ICD has considerable theoretical advantages in selected patients without pacing indications, particularly children and young adults. Although sensing in an S-ICD may be influenced by age, pathology, and posture, there are currently few published data on clinical sensing performance outside the setting of intra-operative testing or in younger patients.

METHODS AND RESULTS

Patients were selected by a multi-disciplinary team on clinical grounds for S-ICD implantation from a broad population at risk of sudden arrhythmic death. Sixteen patients underwent implantation [median age 20 years (range 10-48 years)]. Twelve had primary electrical disease and four had congenital structural heart disease. There were no operative complications, and ventricular fibrillation (VF) induction testing was successful in all cases. During median follow-up of 9 months (range 3-15 months), three children required re-operation. Eighteen clinical shocks were delivered in six patients. Ten shocks in four patients were inappropriate due to T-wave over-sensing. Within the eight shocks for ventricular arrhythmia, three were delivered for VF, among which two had delays in detection with time to therapy of 24 and 27 s.

CONCLUSION

The S-ICD is an important new option for some patients. However, these data give cause for caution in light of the limited published data regarding clinical sensing capabilities, particularly among younger patients.

Long-term outcome of transvenous bipolar atrial leads implanted in children and young adults with congenital heart disease

AIMS

Atrial leads are often implanted in paediatric patients needing a pacemaker (PM). The aim of this study is the evaluation of their outcome in young patients.

METHODS AND RESULTS

We evaluated transvenous atrial leads outcome in children and young adults from a single centre, with a retrospective analysis. A P< 0.05 was considered significant. Between 1992 and 2008, 110 patients, 75 with congenital heart defects (d-transposition of great arteries status/post, s/p, Mustard 41%, atrioventricular septal defect 11%, tetralogy 9%, ventricular septal defect 8%), aged 13.3 ± 5.3 years, underwent PM implantation with bipolar atrial transvenous leads for sinus node dysfunction (50%), atrioventricular block (38%), cardiomyopathies, and primary ventricular arrhythmias (12%). Leads are steroid-eluting (98%), tined (59%), screw-in (41%), polyurethane-insulated (72%), silicone-insulated (28%), and have been positioned by transcutaneous puncture of subclavian vein into right atrial appendage/remnant (RAA, 50%), right atrial free wall/septum (25%), left atrium (s/p Mustard, 25%). Follow-up duration is 6.4 ± 4.8 (range 0.1-18) years. At multivariate analysis, younger age at implant was a risk factor for lead failure (4 leads, 3.5%) (P= 0.03); 16 leads (14%) dislodged post-implantation and 12 were successfully repositioned, the others extracted or abandoned. Dislocation occurred more frequently with screw-in leads (P= 0.03) positioned outside RAA (P= 0.02). Atrial threshold showed a small but significant increase, 0.002 V/month (P< 0.001), impedance showed a decrease (0.6 Ω/month, P< 0.001), P-wave showed no significant difference.

CONCLUSIONS

Transvenous bipolar atrial leads have good long-term results in young patients, with a very low rate of lead failure. Older age at implant can further reduce this rate. Lead dislodgement is frequent in the post-operative period.

How to truly value implantable cardioverter-defibrillators technology: up-front cost or daily cost?

BACKGROUND

We calculated the daily cost of implantable cardioverter-defibrillators (ICDs) based on their actual longevity to prove whether the up-front cost is a reliable parameter for the ICD purchasing-process. METHODS. Longevity of single chamber (SC), double chamber (DC), and biventricular (BiV) ICDs from Medtronic (MDT), Guidant (GDT), and St. Jude Medical (SJM) was measured in all the patients implanted in years 2000, 2001, 2002 who reached device replacement within December 31, 2009. The cost of each ICD (device + lead/s) was normalized for its own longevity. Data are expressed as median (25th-75th percentile).

RESULTS

A total of 123/153 patients completed the study, 70 percent being alive 8 years after implantation. MDT devices had a superior longevity compared with GDT and SJM (p < .001). Fifty-eight percent of replaced ICDs had a service life at least 1 year shorter than the manufacturers' prediction. Longer-lasting devices had a significantly lower daily cost: €4.8 (4.6-5.7) versus €6.8 (6.2-9.2) and €6.9 (6.2-7.6) for SC (p < .001); €6.9 (6.8-7.7) versus €12.6 (11.8-13.3) and €13.4 (10.3-16.1) for DC; €8.5 (8.3-10.3) versus €15.4 (15.1-15.8) and €14.6 (14.1-14.9) for BiV (p < .005).

CONCLUSIONS

The true cost of ICD treatment is strictly dependent on device longevity, whereas device up-front cost is unreliable. This aspect should be valued in the technology purchasing process, and could set the basis for an outcome-based reimbursement system. Our observations may be the benchmark respectively for ICD longevity and daily ICD cost in future comparisons. Independent observations in the real-life scenario are needed to properly value newer technologic improvements.

Infective endocarditis in congenital heart disease

Congenital heart disease (CHD) has become the leading risk factor for pediatric infective endocarditis (IE) in developed countries after the decline of rheumatic heart disease. Advances in catheter- and surgery-based cardiac interventions have rendered almost all types of CHD amenable to complete correction or at least palliation. Patient survival has increased, and a new patient population, referred to as adult CHD (ACHD) patients, has emerged. Implanted prosthetic material paves the way for cardiovascular device-related infections, but studies on the management of CHD-associated IE in the era of cardiovascular devices are scarce. The types of heart malformation (unrepaired, repaired, palliated) substantially differ in their lifetime risks for IE. Streptococci and staphylococci are the predominant pathogens. Right-sided IE is more frequently seen in patients with CHD. Relevant comorbidity caused by cardiac and extracardiac episode-related complications is high. Transesophageal echocardiography is recommended for more precise visualization of vegetations, especially in complex type of CHD in ACHD patients. Antimicrobial therapy and surgical management of IE remain challenging, but outcome of CHD-associated IE from the neonate to the adult is better than in other forms of IE.

CONCLUSION

Primary prevention of IE is vital and includes good dental health and skin hygiene; antibiotic prophylaxis is indicated only in high-risk patients undergoing oral mucosal procedures.

Axillary versus infraclavicular placement for endocardial heart rhythm devices in patients with pediatric and congenital heart disease

Our objective was to evaluate the implant and mid-term outcomes of transvenous pacemaker or internal cardioverter-defibrillator placement by alternative axillary approaches compared to the infraclavicular approach in a pediatric and congenital heart disease population. We conducted a retrospective review of all patients with new endocardial heart rhythm devices placed at 4 pediatric arrhythmia centers. A total of 317 patients were included, 63 had undergone a 2-incision axillary approach, 51 a retropectoral axillary approach, and 203 an infraclavicular approach. Congenital heart disease was present in 62% of the patients. The patients with the 2-incision axillary approach were younger and smaller. The patients with the retropectoral axillary approach were less likely to have undergone previous cardiac surgery and were more likely to have had an internal cardioverter-defibrillator placed. The duration of follow-up was 2.4 ± 1.9 years for the 2-incision axillary, 2.6 ± 2.6 years for retropectoral axillary, and 3.5 ± 1.4 years for the infraclavicular technique (p = 0.01). No differences were seen in implant characteristics, lead longevity, implant complications, lead fractures or dislodgements, inappropriate internal cardioverter-defibrillator discharges, or device infections among the 3 groups. In conclusion, our data support that the outcomes of axillary approaches are comparable to the infraclavicular approach for endocardial heart rhythm device placement and that axillary approaches should be considered a viable option in patients with pediatric and congenital heart disease.

Long-term RV threshold behavior by automated measurements: safety is the standpoint of pacemaker longevity!

BACKGROUND

We studied long-term right ventricular (RV) pacing threshold (RVPT) behavior in patients consecutively implanted with pacemakers capable of automatic output reprogramming tracked by automatic RV threshold measurement (automatic verification of capture [AVC]).

METHODS

All the patients had state-of-the art steroid-eluting bipolar pacing leads and were RV-paced by an AVC algorithm from the three American manufacturers. Follow-up occurred twice in the first year after implantation, then yearly until approaching elective replacement indicator.

RESULTS

Three hundred and twenty-one patients aged 73 ± 12 years were observed for 49 ± 26 months on average. At implantation, RVPT was 0.54 ± 0.2 V at 0.4 ms at an average 774 ± 217 Ω impedance. Forty-one of the 321 patients (12.8%) had a permanent RVPT increase above 1.5 V at 0.4 ms: RVPT was between 1.6 and 2.5 V in 29 of 321 (9%) patients, whereas it was between 2.6 and 3.5 V in seven of 321 (2.2%) patients, and >3.5 V in five of 321 (1.5%) patients. No exit block occurred because of automatic RV output adjustment by AVC algorithms. No predictor of RVPT increase was found at multivariable analysis. The maximum RVPT increase occurred within 12 months from implantation in 19 of 321 (5.9%) patients, between the first and the second year in 12 of 321 (3.7%), between the second and the sixth year in eight of 321 (2.5%), and after the sixth year in two of 321 (0.6%).

CONCLUSION

Despite technologic improvement in lead manufacturing, long-term increase of the RVPT occurs in about 13% of patients, possibly representing a serious safety issue in 3.7% when 2.5 V at 0.4 ms is exceeded. AVC algorithms can improve patients' safety by automatic tailoring of the pacing output to threshold fluctuations, while maximizing device longevity.

Actual pacemaker longevity: the benefit of stimulation by automatic capture verification

BACKGROUND

We evaluated the impact of an algorithm for automatic right ventricular (RV) stimulation compared to fixed-output pacing (FOP) stimulation on actual pacemaker longevity over a 9-year follow-up.

METHODS

Prospective observation of 300 patients implanted with VDDR/DDDR pacemakers in 1999-2000 up to October 31, 2008. Sixty-one patients were paced by Autocapture pacing (ACP), 239 were paced by FOP; they were seen twice yearly at the pacemaker clinic. Factors known to affect pacemaker longevity were collected: median heart rate, %A&V paced activity, pacing output, and impedance. Patients dead before pacemaker replacement, lost to follow-up, or who developed permanent atrial fibrillation were excluded from analysis.

RESULTS

One hundred twenty-six of three hundred patients completed the study. Adverse clinical events due to an increased RV threshold occurred in two FOP patients compared to none among ACP. Pacemaker replacement occurred in 1/34 ACP patients versus 60/92 FOP patients (P < 0.001). ACP was the single independent predictor of pacemaker longevity at multivariable analysis (hazard ratio = 0.03, P < 0.001) either in the overall population or in the specific patients subgroups (sick sinus syndrome, atrioventricular block, and neurally mediated syncope).

CONCLUSIONS

Automatic verification of stimulation is reliable at long term, and warrants superior safety in the event of pacing threshold changes. It allows a significant longevity increase compared to FOP stimulation that may heavily impact the patients' quality of life and the cost of pacing therapy. Moreover, it is a fundamental technology in a strategy of remote patient and device monitoring, and may enable automatic device follow-up operated by trained, nonmedical personnel.

Update on cardiovascular implantable electronic device infections and their management: a scientific statement from the American Heart Association

Despite improvements in cardiovascular implantable electronic device (CIED) design, application of timely infection control practices, and administration of antibiotic prophylaxis at the time of device placement, CIED infections continue to occur and can be life-threatening. This has prompted the study of all aspects of CIED infections. Recognizing the recent advances in our understanding of the epidemiology, risk factors, microbiology, management, and prevention of CIED infections, the American Heart Association commissioned this scientific statement to educate clinicians about CIED infections, provide explicit recommendations for the care of patients with suspected or established CIED infections, and highlight areas of needed research.

Problems with implantable cardiac device therapy

Implantable cardioverter-defibrillators (ICDs) improve survival in patients who have left ventricular dysfunction; however, they are associated with numerous problems at implant and during follow-up. The diagnosis and management of these problems is usually straightforward, but more difficult problems may include the management of patients who have elevated energy requirements to terminate ventricular fibrillation or of those who have postoperative device infections. Long-term issues in ICD patients include the occurrence of inappropriate or frequent appropriate shocks. ICD generators and leads are more prone to failures than are pacing systems alone; management of patients potentially dependent on "recalled" devices to deliver life-saving therapy is a particularly complex issue. The purpose of this article is to review the diagnosis and management of these more troublesome ICD problems.

Pacemaker Infections: A 10-Year Experience

BACKGROUND

Infection is a major complication of pacemaker and defibrillator (PPM/ICD) implantation. The experience in an Australian regional centre is reported.

METHODS

Ten years' (1994-2004) cases of PPM/ICD infection retrospectively analysed and compared to overall insertion data; management and outcomes examined.

RESULTS

A total 39 cases (79.5% male, median age 71.3 years) identified, 24 in the primary centre where 1481 procedures performed (infection rate 1.6%). Patients with infection had average 2.2 procedures performed (odds ratio for infection if >1 procedure=4.7); 14 (36%) first implantations, 35 (90%) pacemakers, 11 (28%) recurrent. No difference in operation duration or difficulty between infected and non-infected cases. Infection in 18 cases (46%) involved lead/s, 16 (41%) generator and 5 (13%) both. Median time to presentation was 7.9 months. Echocardiography demonstrated lead vegetations in 8 cases. Organisms identified in 25 (64%)-92% Staphylococci (65% S. aureus); blood cultures positive in 18. PPM/ICD removed in 26 (67%), including lead/s in 89%; average hospital stay 37 days. One death attributable to PPM/ICD infection (mortality 2.6%), median follow-up 29.3 months.

CONCLUSIONS

A PPM/ICD infection rate of 1.6% (endocarditis 0.3%) demonstrated. Second and subsequent procedures carried almost 5 times greater infection risk.

Risk Factors Related to Infections of Implanted Pacemakers and Cardioverter-Defibrillators

Background— The Prospective Evaluation of Pacemaker Lead Endocarditis study is a multicenter, prospective survey of the incidence and risk factors of infectious complications after implantation of pacemakers and cardioverter-defibrillators.

Methods and Results— Between January 1, 2000, and December 31, 2000, 6319 consecutive recipients of implantable systems were enrolled at 44 medical centers and followed up for 12 months. All infectious complications were recorded, and their occurrence was related to the baseline demographic, clinical, and procedural characteristics. Among 5866 pacing systems, 3789 included 2 and 117 had >2 leads; among 453 implantable cardioverter-defibrillators, 178 were dual-lead systems. A total of 4461 de novo implantations occurred and 1858 pulse generator or lead replacements. Reinterventions were performed before hospital discharge in 101 patients. Single- and multiple-variable logistic regression analyses were performed to identify risk factors; adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated. At 12 months, device-related infections were reported in 42 patients (0.68%; 95% CI, 0.47 to 0.89). The occurrence of infection was positively correlated with fever within 24 hours before the implantation procedure (aOR, 5.83; 95% CI, 2.00 to 16.98), use of temporary pacing before the implantation procedure (aOR, 2.46; 95% CI, 1.09 to 5.13), and early reinterventions (aOR, 15.04; 95% CI, 6.7 to 33.73). Implantation of a new system (aOR, 0.46; 95% CI, 0.24 to 0.87) and antibiotic prophylaxis (aOR, 0.4; 95% CI, 0.18 to 0.86) were negatively correlated with risk of infection.

Conclusions— This study identified several factors of risk of device infection and confirmed the efficacy of antibiotic prophylaxis in recipients of new or replacement pacemakers or implantable cardioverter-defibrillators.

Upgrading of VVIR pacemakers with nonfunctional endocardial ventricular leads to VDD pacemakers in adolescents

BACKGROUND

In some children with ventricular rate responsive demand (VVIR) pacemakers (PM), transvenous leads fail for technical reasons or patient's growth.

AIM

The aim of this study is to describe our experience in adolescents with a nonfunctional ventricular lead in whom the lead was abandoned and an additional VDD lead was implanted. Of the 136 children who received a VVIR PM with an endocardial lead in our center, seven patients aged 7 (0.3-12) years [median (range)] at initial implantation, after 10 (5-15) years showed lead malfunction and underwent atrial synchronous ventricular inhibited pacing (VDD) PM upgrading at 16 (10-20) years.

RESULTS

The VDD lead was inserted through the ipsilateral subclavian vein in five patients, the contralateral in two (venous occlusion in one and for operator choice in the first patient). The tip was positioned into the right ventricular apex, the atrial dipole along the lateral atrial wall. Fluoroscopy times were not significantly different from those measured in SSI PM implantation and in VVIR dual-chamber demand pacing (VVIR-DDD) upgrading. There were no intraprocedural complications. Follow-up duration is 12 (6-62) months. The VDD PM showed good function, no undersensing or oversensing. Tricuspid damage, new venous occlusion, and "twisting" of the two leads at x-ray were not documented. The first patient showed an infection of the old PM pocket after 1 year, local pain after 3 years, and endocarditis of the leads after 5 years.

CONCLUSION

The upgrading of VVIR PM to VDD PM with the abandonment of the nonfunctional lead is feasible, with no intraprocedural complications and good PM function. Lead endocarditis occurred in one patient.

Comparison of Modern Steroid-Eluting Epicardial and Thin Transvenous Pacemaker Leads in Pediatric and Congenital Heart Disease Patients

OBJECTIVE

Optimal pacemaker lead choice in pediatric patients eligible for either epicardial or transvenous leads remains unclear. We compared performances of modern thin transvenous (TTV) and steroid-eluting epicardial (SEE) leads in patients followed at one pediatric center.

METHODS

Retrospective review of patients with qualifying leads implanted from August 1997 to March 2004. Threshold energy (TE) at implant and follow-up, sensing thresholds, lead complications, and repeat pacing-related procedures were analyzed. Lead performances were compared using t-tests, Wilcoxon rank-sum tests and Cox regression. Survival curves were plotted using Kaplan-Meier analysis.

RESULTS

A total of 370 implant procedures, 521 leads, and 1549 visits were evaluated. In all, 256 leads were SEE (49%, 184 implants) and 265 were TTV (51%, 186 implants). Median follow-up was 29 months (range 1-80 months). Patients with SEE systems were younger at implant (6 vs. 17 yrs, p < 0.001), and more had congenital heart defects (82% vs. 57%, p < 0.001). At follow-up, ventricular TEs were higher for SEE leads at implant (p < 0.001), 1 month (p < 0.001), and up to 4 years (p = 0.019). When compared across all follow-up durations combined, TTV TEs were significantly lower than SEE TEs for both atrial and ventricular leads (p < 0.001). A total of 70 repeat procedures were performed in 60 patients during the study period, which comprised 18% of SEE and 14% of TTV system patients (p = NS). In all, 18 TTV and 19 SEE leads failed (p = NS). Estimated freedom from lead failure at 1, 3, and 5 years was 97%, 88%, 85% for TTV leads and 96%, 92%, and 58% for SEE leads (log rank P = NS).

CONCLUSIONS

Both SEE and TTV leads showed good mid-term performance and survival in our cohort. Higher TEs seen for SEE leads, especially ventricular and unipolar leads, may result in higher current drain and thus more generator replacements than TTV systems. Lead failure rates were comparable across lead types. TTV leads offer a promising alternative to SEE systems in terms of performance for young patients without intracardiac shunting who do not require open-chest surgery for another indication.

[Pediatric cardiac pacing: indications, implant techniques, pacing mode]

Over the last years, pacing leads design and pacemaker (PM) generator size, reliability, and longevity have markedly improved, so that reliable paediatric implant can now be performed at any age with a low complication rate. Main indications include congenital and postoperative atrioventricular block (AVB) and postoperative sick sinus syndrome. Implantation of a PM is mandatory for children who are symptomatic from syncope or congestive heart failure and for those who have advanced block persisting more than 10 days after cardiac surgery. Criteria for pacing have been established in relation with the bradycardia and prophylactic pacing is recommended in children with congenital AVB and a mean heart rate <50 beats/minute. The majority of paediatric cardiologists recommend epicardial pacing in children less than 10 kg and when venous access to the heart is limited by congenital anomalies or prior operation; for older children, transvenous implantation has become the technique of choice. As heart rate is the main determinant of cardiac output at exercise in children with normal heart structures, the VVI-R mode is an alternative to dual chamber transvenous pacing in young patients. Patients with isolated sinus failure are paced in the atrium. Although the majority of patients are doing well, late complications within the paediatric population include venous thrombosis and difficulties in lead extraction. Myocardial dysfunction in children with congenital AVB is increasingly reported, but it is not determined whether it is due to the underlying disease or to right ventricular apical pacing and adverse remodelling.

Recent advances in pacemaker and implantable defibrillator therapy for young patients

PURPOSE OF REVIEW

This review is intended to highlight major clinical advances over the past year related to (1). biventricular pacing as a treatment for dilated myopathy, (2). growing clinical experience with implantable cardioverter defibrillators in pediatrics, (3). technical advances in standard antibradycardia pacing, and (4). an appraisal of the newly updated ACC/AHA/NASPE guidelines for device implant in children and adolescents.

RECENT FINDINGS

Complex rhythm devices are being used more frequently in children. Biventricular pacing to improve ventricular contractility is a rapidly evolving technology that has now been applied to children and young adults with intraventricular conduction delay, such as bundle branch block after cardiac surgery. Implantable defibrillators are also being used for an expanding list of conditions, although lead dysfunction is seen as a fairly common complication in active young patients. Guidelines for device implantation have been developed, but the weight of evidence remains somewhat limited by the paucity of pediatric data in this field.

SUMMARY

Thanks to refinements in lead design and generator technology, coupled with rapidly expanding clinical indications, pacemakers and implantable defibrillators have become increasingly important components of cardiac therapy for young patients. Expanded multicenter clinical studies will be needed to develop more objective guidelines for use of this advanced technology.

Pacemaker and defibrillator lead extraction

PURPOSE OF REVIEW

Continued growth in the elderly population and expanding indications have resulted in a progressive increase in the number of implants of pacemakers and defibrillators. Concomitant with these expanding numbers, more leads require removal, due especially to mechanical dysfunction, the need to upgrade to more complex devices, or local or systemic infection. Further, leads have become more complex, particularly for defibrillator systems, resulting in the development of powered extraction sheaths to expedite their removal. For these reasons, it is important to understand the expanding indications, procedural aspects, and limitations of arrhythmia device extraction.

RECENT FINDINGS

Expanded indications for lead extraction include upgrade to more complex systems, particularly pacemaker to defibrillator or biventricular device, extraction through occluded vasculature to produce a conduit for reimplantation, more frequent removal due to vascular overload with multiple leads, and a finite frequency of infection, occurring particularly with device replacement or revision. Powered sheaths now include laser and electrocautery systems, both improving the ease of lead explantation.

SUMMARY

Complication rates remain low but constant with extraction of larger numbers of leads using new technologies. Expansion of the use of biventricular systems, with implantation of coronary sinus electrodes, will continue to challenge lead extraction in terms of technology and safety. Design of leads that are easier to remove remains of paramount importance.