Chronic ventricular pacing in children: toward prevention of pacing-induced heart disease

Conduction System Pacing in Pediatrics and Congenital Heart Disease: A Case Report and Literature Review

Conduction system pacing involving either His bundle pacing (HBP) or left bundle branch pacing (LBBP) is a modality that has been introduced as a safe and effective alternative to right ventricular (RV) pacing to help prevent pacemaker-associated cardiomyopathy. While HBP has been employed in the pediatric and congenital populations, several small studies have shown LBBP to be safe and effective in the pediatric population. We present a patient with congenital atrioventricular block and postoperative ventricular septal defect repair cardiomyopathy with subsequent left ventricular function improvement following a transition from an RV epicardial pacemaker system to an LBBP system. This case report serves as a foundation for a review of the current state of LBBP in pediatrics and congenital heart disease.

miR Profile of Chronic Right Ventricular Pacing: a Pilot Study in Children with Congenital Complete Atrioventricular Block

Chronic ventricular pacing can lead to pacing-induced cardiomyopathy (PICM). Clinical data alone is insufficient to predict who will develop PICM. Our study aimed to evaluate the circulating miR profile associated with chronic right ventricular pacing in children with congenital complete AV block (CCAVB) and to identify candidate miRs for longitudinal monitoring. Clinical data and blood were collected from chronically paced children (N = 9) and compared with non-paced controls (N = 13). miR microarrays from the buffy coat revealed 488 differentially regulated miRs between groups. Pathway analysis predicted both adaptive and maladaptive miR signaling associated with chronic pacing despite preserved ventricular function. Greater profibrotic signaling (miRs-92a, 130, 27, 29) and sodium and calcium channel dysregulation (let-7) were seen in those paced > 10 years with the most dyregulation seen in a patient with sudden death vs. those paced < 10 years. These miRs may help to identify early adverse remodeling in this population.

To go left or right? Driving towards the best direction in paediatric pacing

BACKGROUND

Permanent pacing in children with isolated congenital complete atrioventricular block may cause left ventricular dysfunction. To prevent it, alternative pacing sites have been proposed: left ventricular epicardial or selective right ventricular endocardial pacing.

AIMS

To compare the functional outcome (left ventricular systolic function and synchrony) in paediatric patients with congenital complete atrioventricular block and left ventricular apical epicardial or right ventricular transvenous mid-septal pacing.

METHODS

Retrospective study. Epicardial leads were implanted by standard surgical technique, transvenous leads by 3D electroanatomic mapping systems. 3D mapping acquired 3D right ventricular local pacing map and defined the narrowest paced QRS site. 3D mapping guided screw-in bipolar leads on that ventricular site. Electrocardiogram (ECG) (QRS duration) and echocardiographic data (synchrony: interventricular mechanical delay, septal to posterior wall motion delay, systolic dyssynchrony index; contractility: global longitudinal strain, ejection fraction) were recorded. Data are reported as median [interquartile ranges]. p < 0.05 was significant.

RESULTS

There were 19 transvenous systems (age 8.8 [6-14] years; right ventricular mid-septum) and 17 epicardial systems (0.04 [0.001-0.6] years; left ventricular apex). Post-implantation QRS significantly widened either in endocardial or in epicardial patients. Most patients reached 4-year follow-up. One-year and 4-year ejection fraction and global longitudinal strain were mostly within normal limits and did not show significant differences between the two groups and between the same endocardial/epicardial group. Synchrony parameters were within normal limits in the two groups.

CONCLUSIONS

Left ventricular apical epicardial pacing and 3D mapping-guided right ventricular mid-septal pacing preserved left ventricular contractility and synchrony in children and adolescents with congenital complete atrioventricular block at short-/mid-term follow-up, without relevant significant differences between the two groups.

Preliminary study on left bundle branch area pacing in children:clinical observation of 12 cases

OBJECTIVE

To explore the safety and feasibility of left bundle branch area pacing (LBBAP) in children.

METHODS

This study observed 12 children attempted LBBAP from January 2019 to January 2021 in the department of pediatric cardiology of Anzhen Hospital prospectively.Clinical data, pacing parameters, electrocardiograms, intracardiac electrograms, echocardiographic measurements and complications were recorded at implant and during follow-up.

RESULTS

The 12 patients aged between 3 and 14 years old and weighted from 13 to 48kg. Eleven patients were diagnosed with third-degree atrioventricular block and 1 patient (case 4) suffered from cardiac dysfunction due to right ventricular apical pacing (RVAP). Left bundle branch area pacing was successfully achieved in all patients with narrow QRS complexes and V₁ lead showed changes like right bundle branch block in the pacing electrocardiogram. Left ventricular ejection fraction in case 4 recovered on the 3rd day after LBBAP. The median of left ventricular end diastolic diameter Z score of the 12 patients decreased from 1.75 to1.05 3 months after implantation (p<0.05). The median of paced QRS duration was 103ms. The median of pacing threshold, R-wave amplitude and impedance were 0.85V, 15mV and 717Ω respectively and remained stable during follow-up. No complications such as loss of capture, lead dislodgement or septal perforation occurred.

CONCLUSIONS

Left bundle branch area pacing can be performed safely in children with narrow QRS duration and stable pacing parameters. Cardiac dysfunction caused by long-term RVAP can be corrected by LBBAP quickly. This article is protected by copyright. All rights reserved.

Outcomes in Congenital and Childhood Complete Atrioventricular Block: A Meta-analysis

BACKGROUND

The long-term outcomes of patients with congenital and childhood complete atrioventricular block (CCAVB/ CAVB) after pacemaker implantation are unclear.

METHODS

We performed a meta-analysis of all the studies of CCAVB. A systematic search of PubMed and CENTRAL databases from 1^st January 1967 to 31^st January 2020 was performed. The quality of studies included was critically appraised using the Newcastle-Ottawa scale, and outcome data were analyzed using the restricted maximum likelihood function.

RESULTS

Twenty-nine studies were eligible for analysis, with a total of 1553 patients. The all-cause-mortality was 5.7 % [95% CI: 2.5-9.9%], while PICM was seen in 3.8% [95% CI: 1.2-7.2]. Diagnosis at birth [effect size (ES)(95%CI): -2.23 (-0.36 to -0.10); p<0.001], presence of congenital heart disease ([ES(95%CI): -0.67 (0.41 to 0.93); p<0.001], younger age at pacemaker implantation ([ES(95%CI): -0.01 (-0.02 to -0.001); p=0.02], and duration of pacing [ES(95%CI): -0.03 (-0.05 to -0.003); p=0.03], were associated with an higher mortality on binominal logistic regression. None of the parameters were significant on multivariate analysis.

CONCLUSION

Pooled proportional mortality in patients with CCAVB and CAVB is 5.7% with an infrequent incidence of PICM (3.8%) in the paced patients with AVB suggesting that pacing in these patients is an effective management strategy with a low incidence of long-term side effects. Registry and randomized data can throw additional light regarding the natural history and appropriate management strategy in these patients. This article is protected by copyright. All rights reserved.

Original Article--Outcomes of Pacing in Egyptian Pediatric Population

Objectives

Permanent pacemakers are widely used in the pediatric population due to congenital and surgically acquired rhythm disturbances. The diversity and complexity of congenital heart diseases make device management a highly individualized procedure in pediatric pacing. We are also faced with special problems in pediatric age group as growth, children’s activity and infection susceptibility. This study aimed to present our institute’s experience in pediatric and adolescent pacemaker implantation and long-term outcomes.

Methods

This cross-sectional observational study included 100 pediatric patients who visited our outpatient clinics at Ain Shams University Hospitals for regular follow up of their previously implanted permanent pacemakers. All patients were subjected to history taking, clinical examination, ECG recording, echocardiography and elaborate device programming. Data about device types, device components’ longevity, subsequent procedures, complications were collected, with comparison between epicardial and endocardial pacemakers.

Results

Our study population ranged in age from 8 months to 18 years (mean 13.12 ± 5.04 years), 51 were males and 53 patients had congenital heart disease. Epicardial pacing represented 26% of our total population using only VVIR pacemakers, while endocardial pacing represented 74% of our population with 58.1% of them being VVIR pacemakers. First battery longevity was higher in endocardial batteries (108 months vs. 60 months, p value: 0.007). First lead longevity was also higher in endocardial leads (105 moths vs. 58 months, p value: 0.006). Complication rate was 25%; 8 patients had early complications (one insulation break in endocardial group). Late complications occurred in 17 patients (10 patients had lead fracture; 9 of them were endocardial, 2 insulation breaks in endocardial leads, 3 patients from epicardial group had lead failure of capture). In total, 16 patients had lead-related complications. There was no statistically significant difference between different lead models regarding lead-related complications.

Conclusion

Pacemakers in children are generally safe, but still having high rates of lead-related complications. Lead failure of capture was more common in epicardial leads. These complications had no relation to the model of the leads. Endocardial pacemakers showed higher first lead and first battery longevity compared to epicardial pacemakers.

His Bundle and Left Bundle Pacing in Pediatrics and Congenital Heart Disease: A Single Center Experience

Long-term right ventricular pacing is associated with left ventricular dysfunction and cardiomyopathy, particularly in pediatric patients and those with congenital heart disease (CHD). Research has shown that pacing-induced cardiomyopathy can be reversed with nonselective or selective His bundle pacing in adults, however, the information available about the use of this type of therapy in pediatrics and CHD is scarce. We performed a retrospective chart review of all the cases of His or left bundle pacing at the University of Minnesota, division of Pediatric Cardiology from January of 2019 to April of 2020. Parametric data are presented as mean ± standard deviation. Non-parametric data are presented as median value with interquartile ranges. Eight patients, ages 8 to 18 years (median of 11.5) and weight from 21.5 to 81.6 kg (median of 40 kg) underwent this procedure successfully. The most common structural heart disease was a repaired peri-membranous ventricular septal defect. Three patients (37.5%) had selective and three (37.5%) had nonselective His bundle pacing, and two patients (25%) had left bundle pacing. There were two cases of pacing-induced cardiomyopathy and each had a 14% and 16% improvement of the ejection fraction after nonselective His bundle pacing. There were no procedural complications. Selective and nonselective His bundle, as well as left bundle pacing may be a feasible procedure in pediatric patients with and without CHD. This procedure may improve pacing-induced cardiomyopathy in this population.

Evolution of ventricular function in children with permanent right ventricular pacing after tetralogy of Fallot repair: A midterm follow-up

OBJECTIVE

We aim to evaluate the midterm effect of chronic apical right ventricular (RV) pacing on right and left ventricular (LV) function using different modalities of echocardiography including conventional echocardiography, tissue Doppler imaging and two-dimension speckle tracking echocardiography.

METHODS

This case-control study enrolled 49 patients divided into two groups: a paced group and a nonpaced group. The paced group included 23 patients that underwent tetralogy of Fallot (TOF) repair and required permanent pacemaker insertion for postoperative complete heart block. The nonpaced group included 26 patients that had TOF repair at the same period.

RESULTS

The median age for the paced and nonpaced groups was 6 and 8 years, respectively (P = .169). The follow-up duration after TOF surgical repair was 4 years for the paced patients and 5 years for nonpaced patients (P = .411). In the nonpaced group, the QRS duration increased and LV global longitudinal strain (GLS) decreased significantly with increasing duration after TOF repair, P value was .006 and .042, respectively. In the paced group, tricuspid annular systolic plane excursion (TAPSE) was significantly correlated with age (r = .578; P = .004) and duration following TOF correction (r = .724; P < .001).

CONCLUSION

Chronic RV apical pacing in children after TOF repair was associated with better clinical status, preservation of RV systolic function, and prevention of progressive QRS prolongation. RV pacing was not associated with progressive deterioration of LV systolic function with increasing the time interval following TOF repair. Therefore, RV pacing can be beneficial in corrected TOF patients presenting with RV failure.

Cardiomyopathy in Children: Classification and Diagnosis: A Scientific Statement From the American Heart Association

In this scientific statement from the American Heart Association, experts in the field of cardiomyopathy (heart muscle disease) in children address 2 issues: the most current understanding of the causes of cardiomyopathy in children and the optimal approaches to diagnosis cardiomyopathy in children. Cardiomyopathies result in some of the worst pediatric cardiology outcomes; nearly 40% of children who present with symptomatic cardiomyopathy undergo a heart transplantation or die within the first 2 years after diagnosis. The percentage of children with cardiomyopathy who underwent a heart transplantation has not declined over the past 10 years, and cardiomyopathy remains the leading cause of transplantation for children >1 year of age. Studies from the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry have shown that causes are established in very few children with cardiomyopathy, yet genetic causes are likely to be present in most. The incidence of pediatric cardiomyopathy is ≈1 per 100 000 children. This is comparable to the incidence of such childhood cancers as lymphoma, Wilms tumor, and neuroblastoma. However, the published research and scientific conferences focused on pediatric cardiomyopathy are sparcer than for those cancers. The aim of the statement is to focus on the diagnosis and classification of cardiomyopathy. We anticipate that this report will help shape the future research priorities in this set of diseases to achieve earlier diagnosis, improved clinical outcomes, and better quality of life for these children and their families.

Transvenous dual-chamber pacemaker after paediatric heart transplantation using left ventricle pacing through the coronary sinus

A 12‐year‐old child with end‐stage heart failure due to restrictive cardiomyopathy was submitted to orthotopic heart transplantation. Primary graft dysfunction required venous arterial extra‐corporeal membrane oxygenation. Heart function normalized, but complete atrioventricular block remained after 3 weeks. A dual‐chamber pacing with transvenous left ventricle pacing through the coronary sinus was performed. At 5‐year follow‐up, the patient is stable with the same pacing system and with preserved ventricular function.

Pacing Induced Ventricular Dysfunction in a Child: Improvement with Reduction in Paced Rate

Right ventricular (RV) pacing can be associated with impairment of left ventricular (LV) function due to electrical dyssynchrony and myocardial remodeling (Janousek et al. in J Cardiovasc Electrophysiol 15:470-474, 2004). RV-pacing induced ventricular dysfunction is reversible by techniques such as biventricular pacing and LV apical or LV free wall pacing or turning the pacemaker off which have all been shown to restore synchrony and improve left ventricular function (Janousek et al. in J Cardiovasc Electrophysiol 15:470-474, 2004; Geldorp et al. in Heart Fail Rev 16:305-314, 2011). We describe an infant with RV-pacing induced cardiomyopathy who improved when the pacing rate was reduced thus demonstrating the relationship between pacing rate and development of LV dysfunction.

A Review of Surgical Atrioventricular Block with Emphasis in Patients with Single Ventricle Physiology

We perceived an increased incidence of surgical atrioventricular (AV) block in patients with single ventricle physiology undergoing two ventricle rehabilitation for hypoplastic left heart syndrome compared to the overall incidence of surgical AV block for our institution. Retrospective investigation of our center's data revealed a statistically significant increase in the incidence of surgical AV block in the single ventricle population and two ventricle rehabilitation population compared to the two ventricle population. Here we review the literature with respect to historic definitions, incidence, risk factors, pre- and post-op management, current indications for pacemaker placement and added cost and comorbidity associated with surgical AV block. We then offer possible strategies for decreasing the incidence of surgical AV block within both the single and two ventricle populations.

Gene Therapy for Restoring Heart Rhythm

Efforts to use gene therapy to create a biological pacemaker as an adjunct or replacement of electronic pacemakers have been ongoing for about 15 years. For the past decade, most of these efforts have focused on the hyperpolarization-activated cyclic nucleotide gated-(HCN) gene family of channels alone or in combination with other genes. The HCN gene family is the molecular correlate of the cardiac pacemaker current, If. It is a suitable basis for a biological pacemaker because it generates a depolarizing inward current primarily during diastole and is directly regulated by cyclic adenosine monophosphate (cAMP), thereby incorporating autonomic responsiveness. However, biological pacemakers based either on native HCN channels or on mutated HCN channels designed to optimize biophysical characteristics have failed to attain the desired basal and maximal physiological heart rates in large animals. More recent work has explored dual gene therapy approaches, combining an HCN variant with another gene to reduce outward current, increase an additional inward current, or enhance cAMP synthesis. Several of these dual gene therapy approaches have demonstrated appropriate basal and maximal heart rates with little or no reliance on a backup electronic pacemaker during the period of study. Future research, besides examining the efficacy of other gene combinations, will need to consider the additional issues of safety and persistence of the viral vectors often used to deliver these genes to a specific cardiac region.

Left ventricular synchrony and function in pediatric patients with definitive pacemakers

BACKGROUND

Chronic right ventricular pacing (RVP) induces a dyssynchronous contraction pattern,producing interventricular and intraventricular asynchrony. Many studies have shown the relationship of RVP with impaired left ventricular (LV) form and function.

OBJECTIVE

The aim of this study was to evaluate LV synchrony and function in pediatric patients receiving RVP in comparison with those receiving LV pacing (LVP).

METHODS

LV systolic and diastolic function and synchrony were evaluated in 80 pediatric patients with either nonsurgical or postsurgical complete atrioventricular block, with pacing from either the RV endocardium (n = 40) or the LV epicardium (n = 40). Echocardiographic data obtained before pacemaker implantation, immediately after it, and at the end of a mean follow-up of 6.8 years were analyzed.

RESULTS

LV diastolic function did not change in any patient during follow-up. LV systolic function was preserved in patients with LVP. However, in children with RVP the shortening fraction and ejection fraction decreased from medians of 41% ± 2.6% and 70% ± 6.9% before implantation to 32% ± 4.2% and 64% ± 2.5% (p < 0.0001 and p < 0.0001), respectively, at final follow-up. Interventricular mechanical delay was significantly larger with RVP (66 ± 13 ms) than with LVP (20 ± 8 ms). Similarly, the following parameters were significantly different in the two groups: LV mechanical delay (RVP: 69 ± 6 ms, LVP: 30 ± 11 ms, p < 0.0001); septal to lateral wall motion delay (RVP: 75 ± 19 ms, LVP: 42 ± 10 ms, p < 0.0001); and, septal to posterior wall motion delay (RVP: 127 ± 33 ms, LVP: 58 ± 17 ms, p < 0.0001).

CONCLUSION

Compared with RV endocardium, LV epicardium is an optimal site for pacing to preserve cardiac synchrony and function.

Permanent cardiac pacing in children: choosing the optimal pacing site: a multicenter study

BACKGROUND

We evaluated the effects of the site of ventricular pacing on left ventricular (LV) synchrony and function in children requiring permanent pacing.

METHODS AND RESULTS

One hundred seventy-eight children (aged <18 years) from 21 centers with atrioventricular block and a structurally normal heart undergoing permanent pacing were studied cross-sectionally. Median age at evaluation was 11.2 (interquartile range, 6.3-15.0) years. Median pacing duration was 5.4 (interquartile range, 3.1-8.8) years. Pacing sites were the free wall of the right ventricular (RV) outflow tract (n=8), lateral RV (n=44), RV apex (n=61), RV septum (n=29), LV apex (n=12), LV midlateral wall (n=17), and LV base (n=7). LV synchrony, pump function, and contraction efficiency were significantly affected by pacing site and were superior in children paced at the LV apex/LV midlateral wall. LV dyssynchrony correlated inversely with LV ejection fraction (R=0.80, P=0.031). Pacing from the RV outflow tract/lateral RV predicted significantly decreased LV function (LV ejection fraction <45%; odds ratio, 10.72; confidence interval, 2.07-55.60; P=0.005), whereas LV apex/LV midlateral wall pacing was associated with preserved LV function (LV ejection fraction ≥55%; odds ratio, 8.26; confidence interval, 1.46-47.62; P=0.018). Presence of maternal autoantibodies, gender, age at implantation, duration of pacing, DDD mode, and QRS duration had no significant impact on LV ejection fraction.

CONCLUSIONS

The site of ventricular pacing has a major impact on LV mechanical synchrony, efficiency, and pump function in children who require lifelong pacing. Of the sites studied, LV apex/LV midlateral wall pacing has the greatest potential to prevent pacing-induced reduction of cardiac pump function.

The zebrafish as a novel animal model to study the molecular mechanisms of mechano-electrical feedback in the heart

Altered mechanical loading of the heart leads to hypertrophy, decompensated heart failure and fatal arrhythmias. However, the molecular mechanisms that link mechanical and electrical dysfunction remain poorly understood. Growing evidence suggest that ventricular electrical remodeling (VER) is a process that can be induced by altered mechanical stress, creating persistent electrophysiological changes that predispose the heart to life-threatening arrhythmias. While VER is clearly a physiological property of the human heart, as evidenced by "T wave memory", it is also thought to occur in a variety of pathological states associated with altered ventricular activation such as bundle branch block, myocardial infarction, and cardiac pacing. Animal models that are currently being used for investigating stretch-induced VER have significant limitations. The zebrafish has recently emerged as an attractive animal model for studying cardiovascular disease and could overcome some of these limitations. Owing to its extensively sequenced genome, high conservation of gene function, and the comprehensive genetic resources that are available in this model, the zebrafish may provide new insights into the molecular mechanisms that drive detrimental electrical remodeling in response to stretch. Here, we have established a zebrafish model to study mechano-electrical feedback in the heart, which combines efficient genetic manipulation with high-precision stretch and high-resolution electrophysiology. In this model, only 90 min of ventricular stretch caused VER and recapitulated key features of VER found previously in the mammalian heart. Our data suggest that the zebrafish model is a powerful platform for investigating the molecular mechanisms underlying mechano-electrical feedback and VER in the heart.

Right or Left Ventricular Pacing in Young Minipigs With Chronic Atrioventricular Block

Background—

Left ventricular (LV) dyssynchrony may occur as a result of right ventricular (RV) pacing and is a known risk factor for the development of heart failure. In children with complete atrioventricular block, pacing-induced dyssynchrony lasting for decades might be especially deleterious for LV function. To determine the hemodynamic and ultrastructural remodeling after either RV free wall or LV apical pacing, we used a chronic minipig model.

Methods and Results—

Fourteen piglets 8 weeks of age underwent atrioventricular node ablation and were paced from either the RV free wall or the LV apex at 120 bpm for 1 year (7 age-matched minipigs served as controls with spontaneous heart rates of 104±5 bpm). Echocardiographic examinations, pressure-volume loops, patch-clamp investigations, and examinations of connexin43, calcium-handling proteins, and histomorphology were carried out. RV free wall–paced minipigs exhibited significantly more LV dyssynchrony than LV apex–paced animals, which was accompanied by worsening of LV function (maximum LV mechanical delay/LV ejection fraction: RV free wall pacing, 154±36 ms/28±3%, LV apical pacing, 52±19 ms/45±2%, control 47±14 ms/62±1%; P =0.0001). At the cellular level, both pacemaker groups exhibited a significant reduction in L-type calcium and peak sodium current, shortening of action potential duration and amplitude, increased cell capacity, and alterations in the calcium-handling proteins that were similar for RV free wall– and LV apex–paced animals.

Conclusions—

The observed molecular remodeling seemed to be more dependent on heart rate than on dyssynchrony. LV apical pacing is associated with less dyssynchrony, a more physiological LV contraction pattern, and preserved LV function as opposed to RV free wall pacing.

[Advances in cardiac pacing]

This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed.