Chronic performance of steroid-eluting epicardial leads in a growing pediatric population: a 10-year comparison

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.

Epicardial Versus Endocardial Pacing in Paediatric Patients with Atrioventricular Block or Sinus Node Dysfunction: A Systematic Review and Meta-analysis

Pacing indications in children are clearly defined, but whether an epicardial (EPI) or an endocardial (ENDO) pacemaker performs better remains to be elucidated. This systematic review and meta-analysis aimed to directly compare the incidence of pacemaker (PM) lead-related complications, mortality, hemothorax and venous occlusion between EPI and ENDO in children with atrioventricular block (AVB) or sinus node dysfunction (SND). Literature search was conducted in MEDLINE (via PubMed), Scopus by ELSEVIER, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, and OpenGrey databases until June 25, 2022. Random-effects meta-analyses were performed to assess the pacing method's effect on lead failure, threshold rise, post-implantation infection and battery depletion and secondarily on all-cause mortality, hemothorax and venous occlusion. Several sensitivity analyses were also performed. Of 22 studies initially retrieved, 18 were deemed eligible for systematic review and 15 for meta-analysis. Of 1348 pediatric patients that underwent EPI or ENDO implantation, 542 (40.2%) had a diagnosis of congenital heart disease (CHD). EPI was significantly associated with higher possibility of PM-lead failure [pooled odds ratio (pOR) 3.00, 95% confidence interval (CI) 2.05-4.39; I2 = 0%]; while possibility for threshold rise, post-implantation infection and battery depletion did not differ between the PM types. Regarding the secondary outcome, the mortality rates between EPI and ENDO did not differ. In sensitivity analyses the results were consistent results between the two PM types. The findings suggest that EPI may be associated with increased PM-lead failure compared to ENDO while threshold rise, infection, battery depletion and mortality rates did not differ.

Intermittent Epicardial Lead Failure Detected Using a Continuous Ambulatory Electrocardiogram Monitor

A 69-year-old man received epicardial pacing leads for complete atrioventricular block that occurred during a mechanical tricuspid valve replacement procedure. During follow-up, the patient reported intermittent episodes of dizziness and bradycardia. Remote transmissions and device interrogations failed to elucidate the cause of his symptoms. A continuous ambulatory electrocardiogram (ECG) monitor was used as an alternative diagnostic tool. Multiple pauses were detected by the monitor and, upon review, these events were deemed to be due to the intermittent loss of capture by the epicardial lead. Once this diagnosis was made and the malfunctioning lead was replaced, the patient’s symptoms resolved. This case highlights the novel use of a continuous ambulatory ECG monitor in diagnosing intermittent loss of capture, which was not detected by remote monitoring or device interrogations.

Mini-invasive technique of implanting the first domestic wireless epicardial pacemaker with a MEMS-converter

This article describes a minimally invasive surgical technique for implanting the pacemaker with a microelectromechanical system (MEMS) converter of kinematic energy into electrical energy in patients with life-threatening rhythm disorders. This kind of technique is recommended for patients with cardiac pathology who are preparing for surgical treatment of the main pathology with simultaneous implantation of the pacemaker with MEMS-converter of kinematic energy into electrical energy. Implantation of the pacemaker should be performed in the most energy-efficient zone of the epicardium, determined in advance by the method of tissue echocardiography.

Minimally Invasive Implantation of a Micropacemaker Into the Pericardial Space

BACKGROUND

Permanent cardiac pacemakers require invasive procedures with complications often related to long pacemaker leads. We are developing a percutaneous pacemaker for implantation of an entire pacing system into the pericardial space.

METHODS

Percutaneous micropacemaker implantations were performed in 6 pigs (27.4-34.1 kg) using subxyphoid access to the pericardial space. Modifications in the implantation methods and hardware were made after each experiment as the insertion method was optimized. In the first 5 animals, nonfunctional pacemaker devices were studied. In the final animal, a functional pacemaker was implanted.

RESULTS

Successful placement of the entire nonfunctional pacing system into the pericardial space was demonstrated in 2 of the first 5 animals, and successful implantation and capture was achieved using a functional system in the last animal. A sheath was developed that allows retractable features to secure positioning within the pericardial space. In addition, a miniaturized camera with fiberoptic illumination allowed visualization of the implantation site before electrode insertion into myocardium. All animals studied during follow-up survived without symptoms after the initial postoperative period.

CONCLUSIONS

A novel micropacemaker system allows cardiac pacing without entering the vascular space or surgical exposure of the heart. This pericardial pacemaker system may be an option for a large number of patients currently requiring transvenous pacemakers but is particularly relevant for patients with restricted vascular access, young children, or those with congenital heart disease who require epicardial access.

Epicardial left ventricular leads via minimally invasive technique: a role of steroid eluting leads

Background

We retrospectively assessed two types of sutureless screw-in left ventricular (LV) leads (steroid eluting vs. non-steroid eluting) in cardiac resynchronization therapy (CRT) implantation with regards to their electrical performance.

Methods

Between March 2008 and May 2014 an epicardial LV lead was implanted in 32 patients after failed transvenous LV lead placement using a left-sided lateral minithoracotomy or video-assisted thoracoscopy (mean age 64 ± 9 years). Patients were divided into two groups according to the type of implanted lead. Steroid eluting (SE) group: 21 patients (Myodex™ 1084 T; St. Jude Medical) and non-steroid eluting (NSE) group: 11 patients (MyoPore® 511,212; Greatbatch Medical).

Results

All epicardial leads could be placed successfully, without any intraoperative complications or mortality. With regard to the implanted lead following results were observed: sensing (mV): SE 8.8 ± 6.1 vs. NSE 10.1 ± 5.3 (p = 0.380); pacing threshold (V@0.5 ms): SE 1.0 ± 0.5 vs. NSE 0.9 ± 0.5 (p = 0.668); impedance (ohms): SE 687 ± 236 vs. NSE 790 ± 331 (p = 0.162). At the follow-up (2.6 ± 1.9 years) the following results were seen: sensing (mV): SE 8.7 ± 5.0 vs. NSE 11.2 ± 6.6 (p = 0.241), pacing threshold (V@0.5 ms): SE 1.4 ± 0.5 vs. NSE 1.0 ± 0.3 (p = 0.035), impedance (ohms): SE 381 ± 95 vs. NSE 434 ± 88 (p = 0.129).

Conclusions

Based on the results no strong differences have been found between the both types of epicardial LV leads (steroid eluting vs. non-steroid eluting) in CRT implantation in short- and midterm.

Surgical Aspects of Cardiac Resynchronisation Therapy

Despite significant advances in the pharmacological treatment of heart failure, rates of mortality and morbidity from the condition remain a concern. The introduction of cardiac resynchronisation therapy (CRT) has been a welcome addition to the treatment strategy of patients who display ventricular dyssynchrony. Several control studies have shown significant benefits from this intervention in particular improved mortality and reduction in symptom burden. In this short review, we focus on several concepts of CRT and discuss the implications of surgical implantation of the left ventricular (LV) lead as compared to the standard transvenous approach.

Single chamber permanent epicardial pacing for children with congenital heart disease after surgical repair

Background

To analyze the 10-year experience of single chamber permanent epicardial pacemaker placement for children with congenital heart diseases (CHD) after surgical repair.

Methods

Between 2002 and 2014, a total of 35 patients with CHD (age: 26.9 ± 23.2 months, weight: 9.7 ± 5.6 kg) received permanent epicardial pacemaker placement following corrective surgery. Echocardiography and programming information of the pacemaker, as well as major adverse cardiac events (MACE) as heart failure or sudden death, were recorded during follow-up (46.8 ± 33.8 months).

Results

Acute ventricular stimulation threshold was 1.34 ± 0.72 V and no significant increase was observed at the last follow-up as 1.37 ± 0.81 V (p = 0.93). Compared with initial pacemaker implantation, the last follow-up didn’t show significant increases in impedance (p = 0.327) or R wave (p = 0.635). Four patients received pacemaker replacement because of battery depletion. 7/35 (20 %) of patients experienced MACE. Although the age and body weight were similar between patients with and without MACE, the patients with MACE were with complex CHD (100 % vs.55.6 %, p = 0.04).

Conclusion

High-degree iatrogenic atrioventricular block was the primary reason for placement of epicardial pacemaker for patients with CHD after surgical repair. Pacemaker placement with the steroid-eluting leads results in acceptable outcomes, however, the pacemaker type should be optimized for the children with complex CHD.

Improving pacemaker therapy in congenital heart disease: contractility and resynchronization

Designed as effective therapy for patients with symptomatic bradycardia, implantable cardiac pacemakers initially served to improve symptoms and survival. With initial applications to the elderly and those with severe myocardial disease, extended longevity was not a major concern. However, with design technology advances in leads and generators since the 1980s, pacemaker therapy is now readily applicable to all age patients, including children with congenital heart defects. As a result, emphasis and clinical interests have advanced beyond simply quantity to quality of life. Adverse cardiac effects of pacing from right ventricular apical or epicardial sites with resultant left bundle branch QRS configurations have been recognized. As a result, and with the introduction of newer catheter-delivered pacing leads, more recent studies have focused on alternative or select pacing sites such as septal, outflow tract, and para-bundle of His. This is especially important in dealing with pacemaker therapy among younger patients and those with congenital heart disease, with expected decades of artificial cardiac stimulation, in which adverse myocellular changes secondary to pacing itself have been reported. As a correlate to these alternate or select pacing sites, applications of left ventricular pacing, either via the coronary sinus, intraseptal or epicardial, alone or in combination with right ventricular pacing, have gained interest for patients with heart failure. Although cardiac resynchronization pacing has, to date, had limited clinical applications among patients with congenital heart disease, the few published reports do indicate potential benefits as a bridge to cardiac transplant.

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.

Failure of epicardial pacing leads in congenital heart disease: not uncommon and difficult to predict

AIMS

We evaluate the incidence of epicardial lead failure and try to identify risk factors in patients with congenital heart disease.

METHODS

All patients with a congenital heart defect and an epicardial pacing system, implanted within a timeframe of 25 years, were included in this study. Patients' medical records and lead data were reviewed. Lead failure was defined as the primary endpoint.

RESULTS

In total 198 active epicardial leads (atrial 40, ventricular 158) were implanted in 93 patients (median age at implantation 4.4 years (range 0-58.6)). During a total follow-up of 1235 lead-years, 29 lead failures (14.6%, 4 atrial, 25 ventricular) were documented in 22 patients (23.7%). Lead failure occurred at a median time period of 4.8 years (range 1.2-24.1) after implantation. Five-year freedom of lead failure was 88%. The only independent predictor for lead failure was the age at implantation (HR 0.44; 95%CI 0.20-0.97, p = 0.04), other characteristics failed to predict lead failure. Sudden cardiac death occurred in four patients (4.3%), in one a lead failure was documented.

CONCLUSION

A high incidence of epicardial lead failures is found in patients with congenital heart disease. Unfortunately, it is difficult to predict this potentially life-threatening complication.

A single institution experience with pacemaker implantation in a pediatric population over 25 years

BACKGROUND

With the development of new technical devices and software more appropriate for pediatric patients, pacemaker implantations in children and young adults have increased over time. It is necessary to monitor the mid- and long-term consequences. The decision for the implantation of a cardiovertor defibrillator (ICD) in children remains challenging despite technical improvements.

OBJECTIVE

To assess the safety of pacemaker implantation in children, to review old and new indications, and to point out changes of management over time.

PATIENTS AND METHODS

Between 1984 and 2009, 181 patients required the implantation of a pacemaker or an ICD device at the Heart and Diabetes Centre in Bad Oeynhausen, Germany. Their charts have been reviewed pro- and retrospectively for indications, complications, longevity of the device, and the natural course.

RESULTS

Indications have been high-degree atrioventricular block in 65% (postoperative 55%) and sinus node dysfunction in 24% (postoperative 90%), including three patients with vasovagally mediated significant bradycardia. Eleven percent required the implantation of an ICD device secondary to significant ventricular arrhythmias. The indication was class II in one-third of all patients. Complications requiring revision occurred in six patients (3.3%); one of them required removal of the device due to an infection. Ten patients died, but none related to pacemaker implantation.

CONCLUSION

Pacemaker implantation even in young pediatric patients is generally safe. No complication led to the death of a patient. The number of class II indications has been increasing. The future aim is to improve pediatric algorithms and to prevent unnecessary pacing.

An epicardial pacing safety net: an alternative technique for pacing in the young

Epicardial pacing is the standard approach for permanent pacing in small children and patients with functionally univentricular physiology. The longevity of epicardial leads, however, is compromised by increased occurrences of exit block and lead fractures. We report our experience with a technique of placing a second ventricular lead, and attaching it to the atrial port of a dual chamber pacemaker to prevent the need for early re-operation in the event of failure of the primary epicardial lead. A retrospective review showed that, over the period from 2001 through 2007, epicardial ventricular pacemakers had been placed in 88 patients. In 6 of these, we had placed 2 ventricular leads, their median weight being 8.0 kilograms, with a range from 4.2 to 31.8 kilograms. Fracture of a lead occurred in 1 of the patients (17%) 8 months after placement, requiring reprogramming to pace from the atrial port. This possibility avoided the need for repeated emergent surgery. At a median follow-up of 1.5 years, with a range from 0.3 to 4.4 years, there have been no complications. During the same time period, overall failure of epicardial leads at our institution was 13%. Placement of a second ventricular epicardial pacing lead, attached to the atrial port of a dual chamber pacemaker, therefore, may provide a safe and effective means of ventricular pacing in the setting of epicardial lead failure, and may obviate the need for repeat, potentially urgent, pacemaker surgery.

Successful cardiac resynchronization with single-site left ventricular pacing in children

BACKGROUND

Dyssynchronous left ventricular (LV) contraction due to permanent right ventricular apex (RVA) pacing or delayed electrical activation as typically observed in left bundle brunch block (LBBB) has a negative impact on LV function. Objective was to evaluate the impact of epicardial single-site LV pacing in children on LV function and resynchronization.

PATIENTS

Single-site epicardial LV free wall pacing was established in 6 children with congenital heart disease and echocardiographic signs of LV dyssynchrony. Reasons for dyssynchrony were either long-term RVA pacing (n=5; pacing duration: 7.7+/-2.4 years) or LBBB with drug-resistant congestive heart failure (n=1).

RESULTS

After 1 month of single-site LV pacing, LV ejection fraction increased (41+/-6 versus 53+/-8%) and LV enddiastolic volume decreased (70+/-22 versus 63+/-18 ml/m(2)) as compared to pre-implant measurements. Interventricular mechanical delay decreased (67+/-15 versus 16+/-15 ms) and intraventricular synchrony was restored (septal-to-posterior wall motion delay: 312+/-24 versus 95+/-57 ms). Accordingly, circumferential 2D strain demonstrated a decrease of LV mechanical delay (201+/-35 versus 99+/-23 ms).

CONCLUSION

After 1 month of single-site LV pacing, conventional and 2D strain derived echocardiographic measurements indicated improved ventricular function and synchronization in children with previous RVA pacing or LBBB. Further studies are needed to evaluate whether single-site LV pacing may be sufficient for resynchronization therapy.

Equivalent performance of epicardial versus endocardial permanent pacing in children: a single institution and manufacturer experience

BACKGROUND

Children requiring permanent pacing have a lifelong need for follow-up. Epicardial leads have traditionally fared worse than endocardial counterparts. We tested the hypothesis that steroid-eluting epicardial and endocardial leads had equivalent outcomes.

METHODS

We reviewed medical records of 148 children, mean age 8.2 +/- 4.8 years, in whom a dual-chamber pacemaker system with steroid-eluting leads from a single manufacturer was implanted. Primary outcome was mortality. Secondary outcomes included freedom from lead failure and pacemaker system reintervention. Loss of capture-sensing, lead displacement-fracture, exit block, and high thresholds constituted lead failure. Reintervention included need for lead revision or generator change.

RESULTS

There was no early mortality. Late mortality occurred once (0.5 +/- 0.5 deaths/1,000 patient-months) and eight times (3.4 +/- 1.2 deaths/1,000 patient-months) in the endocardial and epicardial groups, respectively. The relative hazard of endocardial versus epicardial site for lead failure was 0.408 (p = 0.038) and for reintervention was 0.629 (p = 0.002). Endocardial and epicardial groups differed in important ways: concomitant cardiac surgery 5% (3 of 61) versus 27% (27 of 99); congenital heart disease 33% (20 of 61) versus 90% (89 of 99); single ventricle physiology 13% (8 of 61) versus 52% (51/99); and age (10.5 +/- 4.5 years vs 5.5 +/- 5.2 years). Adjusting for these covariants, the relative hazard for freedom from lead failure for endocardial versus epicardial leads was 0.546 (p = 0.360). The adjusted relative hazard for freedom from reintervention was 0.157 (p = 0.045).

CONCLUSIONS

Technologic advances attenuate important differences in lead failure rates between endocardial and epicardial steroid-eluting pacing leads and thus bridge the performance gap between these fixation modes.

Pacemaker Lead Prolapse through the Pulmonary Valve in Children

BACKGROUND

Transvenous pacemaker leads in children are often placed with redundant lead length to allow for anticipated patient growth. This excess lead may rarely prolapse into the pulmonary artery and potentially interfere with valve function. We sought to determine the response to lead repositioning on pulmonary valve insufficiency.

METHODS

Retrospective reviews of demographics, lead type, implant duration, and radiography and echocardiography.

RESULTS

A total of 11 pediatric patients were identified with lead prolapse through the pulmonary valve, of which nine patients underwent procedures to retract and reposition the lead (age at implant 9 +/- 4 years, age at revision 13 +/- 4 years). The implant duration prior to revision was 4 +/- 3 years. Two leads required radiofrequency extraction sheaths for removal, two pulled back using a snare, while five leads were simply retracted and repositioned. Tricuspid regurgitation was none/trivial (three), mild (four), or moderate (two) and only two improved with repositioning or replacement. Pulmonary regurgitation preoperatively was mild (three), mild-moderate (two), or moderate (four) compared with trivial (three), mild (four), and moderate (two) after revision. Patients with longer-term implanted leads had less improvement in pulmonary insufficiency. Two patients had mild pulmonary stenosis from lead-related obstruction.

CONCLUSIONS

Prolapse of transvenous pacing leads into the pulmonary artery can occur when excess slack is left for growth. Leads can often be repositioned, but may require extraction and replacement, particularly if chronically implanted and adherent to valve apparatus. Lead revision does not always resolve pulmonary insufficiency, potentially leaving permanent valve damage.

Do daily threshold trend fluctuations of epicardial leads correlate with pacing and sensing characteristics in paediatric patients?

AIMS

To evaluate whether the magnitude of daily ventricular pacing threshold fluctuations (Deltafluctuation) in trend graphs of stored diagrams correlate with ventricular threshold and sensing changes over time.

METHODS AND RESULTS

A total of 56 children received AutoCapture devices (St. Jude Medical, Sylmar, CA, USA) connected to steroid-eluting epicardial leads. Maximum lead age at study closure was 12.2 years (median 4.0). Telemetry data and daily Deltafluctuation were obtained every 6 months. Regression slope coefficients and mean values of repeated measurements were calculated for each patient's course. High daily Deltafluctuation correlated with higher pacing thresholds (rho = 0.68, P < 0.001), lower impedances (rho = -0.38, P = 0.004), and a Deltafluctuation-incline (rho = 0.34, P = 0.01) over time. Furthermore, a Deltafluctuation-incline correlated with a pacing threshold-incline (rho = 0.34, P = 0.01). No correlation was observed for ventricular sensing. Higher daily Deltafluctuation were observed if lead age was > 5 years compared with <or= 5 years (0.75 vs. 0.55 V@0.5 ms, P = 0.028).

CONCLUSION

High amplitudes of daily Deltafluctuation correlate with higher and increasing pacing thresholds and lower impedances. Theoretically, this results from electrode microinstability on the epicardial surface. A decrease of the steroid-eluting potency of the electrode can be hypothesized to cause higher daily Deltafluctuation beyond a lead age of 5 years. Potential implications of marked daily Deltafluctuation are short-term follow-up and lead replacement in the presence of high pacing thresholds.

Single-centre experience on endocardial and epicardial pacemaker system function in neonates and infants

AIMS

Endocardial (ENDO) or epicardial (EPI) pacing systems are implanted in infants but it remains unclear which system should be preferred.

METHODS AND RESULTS

We evaluated the results of children <or=1 year who underwent pacemaker (PM) implantation at our centre with a retrospective analysis. Between 1992 and 2004, 56 patients, 37 of whom had other congenital heart defects (CHDs), received a PM at 4.4 +/- 3.8 months of age for atrioventricular block (n = 52) and sinus node dysfunction. Rate-responsive ventricular demand pacing (VVIR) PMs were implanted in 25 patients (19 ENDO), dual-chamber demand pacing (DDD) in 29, and rate-responsive atrial demand pacing (AAIR) in 2 (all EPI). Follow-up (FU) was 4.5 +/- 3.5 (range 0.3-13) years: 15 pacing system failures occurred among the 56 patients (26%) after 4.5 +/- 3.2 years, with a significantly reduced success rate for EPI (21-fold increase of the risk of failure) and complex CHD. Also in patients without surgery for CHD, EPI showed a worse outcome. Among the 91 leads implanted, failures occurred more significantly in EPI (18% of atrial, 24% of ventricular leads) than in ENDO (5% of ventricular leads). No venous occlusion was found at FU.

CONCLUSIONS

Single-lead, VVIR ENDO pacing had higher efficiency and safety than EPI, and it might be the best choice for PM implantation in infants. However, because of small patient numbers and lack of longer FU, these findings should be treated with caution.

Pacing in adults with congenital heart disease

Adults with congenital heart disease constitute one of the fastest growing populations in cardiology. Pacing is an integral part of their therapy and may reduce their morbidity and mortality significantly. The current generation of pacemakers is more sophisticated and complex, and they are being utilized for indications other than conduction abnormalities, such as termination of tachycardia and improvement of heart failure. The complex anatomy and history of multiple previous surgeries in adults with congenital heart disease, however, pose many limitations and technical challenges related to the placement of a pacemaker. Unique and innovative approaches to endocardial lead placement and improved epicardial leads is making pacemaker implantation more feasible in these patients.

Fractally coated myocardial pacemaker leads in children

We report our single centre experience with a new fractally coated myocardial unipolar lead (ELC35UP; Biotronik) in 96 pediatric patients (59% male, 41% female). Congenital heart disease (CHD) was associated in 89%. The age at implantation ranged between 2 days and 19 years, median for children with CHD 7.8 years, without CHD 4.7 years. Twenty percent of the children were younger than one year at implantation. Mean follow-up was 30 months (1-57 months). We compared our findings with a steroid eluting epicardial lead (CapSure EPI 4968; Medtronic) in 46 children with comparable age and sex-distribution. We found a lead survival of 87% after 57 months in the ELC35UP group (steroid lead: 87% after 129 months). Pacing energy thresholds were equal after 12 months (median 3.0 microjoules), but the sensing characteristics of the fractally coated lead was significantly superior to the steroid eluting lead with median R waves of 7.0 mV (steroid lead: 3.5 mV) after 12 months. Children with myocardial scar tissue requiring pacemaker therapy after surgery of CHD showed no differences in sensing and pacing thresholds in comparison to children with congenital rhythm disorders. The fractally coated screw-in lead offers technical advantages concerning the subxiphoidal implantation procedure.

CONCLUSION

Fractally coated ventricular screw-in leads represent a feasible alternative to the common steroid eluting leads- especially in children requiring pacemaker therapy after surgery for CHD.

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.

Sympathetic Nerve Activity After Thoracoscopic Cardiac Resynchronization Therapy in Congestive Heart Failure

BACKGROUND

Sympathetic benefits of thoracoscopic cardiac resynchronization therapy (TCRT) in congestive heart failure (CHF) are unknown. We determined cardiac hemodynamics, functional status, and muscle sympathetic nerve activity (MSNA) in a group of TCRT patients. We aimed to compare these patients with CHF patients with cardiac asynchrony (ASY) to substantiate the beneficial effects of TCRT.

METHODS AND RESULTS

Eleven patients resynchronized by TCRT 6 +/- 1 months before study inclusion (SYN) and 10 matched ASY patients underwent blood pressure, heart rate, and MSNA recordings. All underwent functional status, cardiac index, and left ventricular ejection fraction (LVEF) assessments. SYN patients had shorter QRS duration and interventricular mechanical delays, longer 6 minute walking distance and lower New York Heart Association class (all P < .05) than ASY patients. MSNA of 56 +/- 2 bursts/min in ASY patients was higher than in SYN patients (48 +/- 3 bursts/min, P < .05). Cardiac index was higher in SYN patients than in ASY patients (2.8 +/- 0.2 versus 1.9 +/- 0.2 L.min.m2, P < .05, respectively). MSNA was highest in the patients with the lowest LVEF (r = -0.49, P < .05), cardiac index (r = -0.48, P < .05) and 6-minute walking distance (r = -0.50, P < .05).

CONCLUSION

Lower sympathetic nerve activities in TCRT patients are related to more favorable cardiac indexes and six minute walking distances suggesting a sympathetic, hemodynamic, and functional improvement by TCRT.

Patient, procedural, and hardware factors associated with pacemaker lead failures in pediatrics and congenital heart disease

OBJECTIVES

To examine outcomes of children with pacemakers over a 22-year period and identify risk factors for lead failure.

BACKGROUND

Small patient size, structural cardiac abnormalities, and growth may complicate pediatric pacemaker management. Better knowledge of risk factors for lead failure in these patients may help improve future outcomes.

METHODS

All pacemaker patients followed at one pediatric center 1980-2002 were included. Lead failures were identified retrospectively as leads repaired, replaced, or abandoned due to fracture, insulation break, dislodgement, or abnormalities in pacing or sensing. Risk factors were identified using logistic regression and Cox analyses.

RESULTS

A total of 1007 leads were implanted in 497 patients during the study period (5175 lead-years). Median age at implant was 9 years (0-55); 64% of patients had structural congenital heart disease. Median follow-up time was 6.2 years (0-22). Lead failure occurred in 155 leads (15%), and 115 patients (23%), with 28% of patients experiencing multiple failures. Significant independent correlates of lead failure included age <12 years at implant, history of structural congenital heart defects, and epicardial lead placement. Younger patients (<12 years) experienced significantly more lead fractures than older children (P = .005), while patients with congenital heart defects experienced more exit block. Epicardial leads were more likely to fail due to fracture or exit block, while transvenous leads failed more due to insulation breaks or dislodgements.

CONCLUSIONS

Pediatric pacing patients have a high incidence lead failures. These occur most commonly in younger patients, structural congenital heart disease, and those with epicardial lead systems. Approaches to pacing system implantation and follow-up in these patients need to be individualized, with special attention to minimizing risk of lead failures. Our findings suggest that expanded utilization of transvenous systems in smaller patients seems justified when anatomy permits.

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.