Predictors of left ventricular remodelling and failure in right ventricular pacing in the young

Changes in Non-invasive Myocardial Stroke Work Related to Variation in Pacing Sites and Heart Rates in Adolescents

Non-invasive assessment of myocardial work is a newly described technique to assess myocardial energetics. This has not been previously studied to assess the effects of right ventricular pacing at different sites or at different heart rates in children. We aimed to study the effects of right ventricular apical, septal, and His bundle pacing on myocardial work along with the effects of increasing heart rate. This was a prospective pilot study performed on six patients with structurally normal hearts and function following an electrophysiology study. Global work index and global work efficiency was highest during His pacing and lowest during right ventricular apical pacing. The global constructive work, index, and efficiency were progressively worse with increasing heart rates. In this prospective pilot study, we demonstrated that myocardial work indices differ depending on myocardial activation pattern and at different heart rates in pediatric patients. Myocardial performance as assessed by myocardial work efficiency is worse when pacing is performed at the right ventricular apex when compared to His and right ventricular septal pacing. Myocardial performance can be affected by higher heart rates, following a work-frequency relationship.

Left bundle branch area pacing in children: case series

Background

Left bundle branch area pacing (LBBAP) is a new concept that provides physiological pacing with a narrow QRS duration. Recently published data suggest that LBBAP may prevent deleterious effects of right ventricular pacing, namely pacemaker-induced cardiomyopathy, especially in patients with expected high ventricular pacing burden, which may be of particular importance in children.

Case summary

Herein, we report successful implantation of Medtronic SelectSecure (Model 3830, Medtronic Inc.) right ventricle electrode in the region of left bundle branch area in three consecutive children (two 16-year-old and one 8-year-old). Indication for pacemaker implantation was third-degree atrioventricular block in all cases. Implantations were performed under general anaesthesia, and there were no acute complications. During the median follow-up of 6 months, there were no adverse events and the electrical parameters of the device remained stable.

Discussion

Compared with adult patients, implantation of pacemakers in children may still be challenging, not only because of smaller body size but also due to continuing growth and a higher rate of lead and device-related complications. We have demonstrated that implantation of LBBAP in children is feasible and could be worth considering, particularly in patients with expected high ventricular pacing burden. Further studies are needed to assess the efficacy and safety of LBBAP in children during long-term observation.

Dual- Vs Single-Chamber Ventricular Pacing in Isolated Congenital Complete Atrioventricular Block in Infancy

BACKGROUND

The optimal pacemaker programming strategy for infants with isolated congenital complete atrioventricular block (CCAVB) remains unresolved. Dual-chamber pacing maintains atrioventricular synchrony and physiological heart rate variability but increases the burden of ventricular pacing on a myocardium that may be inherently prone to left ventricular (LV) dysfunction.

OBJECTIVES

This study sought to compare clinical outcomes of dual (DDD)- vs single (VVI)- chamber pacing in infants with CCAVB (DAVINCHI).

METHODS

A multicenter retrospective study (2006-2023) identified infants with CCAVB and pacemaker implant at <1 year, with single-site ventricular pacing and no significant congenital heart disease. Outcome measured were clinically significant LV dysfunction, mortality, and complications.

RESULTS

A total of 109 infants (64% autoimmune CCAVB) were identified, 60.6% had VVI pacing. Over a median follow-up of 5 years, 60 complications occurred in 47 subjects (43.1%). Smaller infants had more complications. Clinically significant LV dysfunction developed in 11 (10.1%) and was more frequent in DDD (21% vs 3%; P = 0.006). LV dysfunction resulted in mortality in 1 patient and 10 patients required a change in pacing mode. Independent risk factors for LV dysfunction were DDD pacing and neonatal implant. Right ventricular pacing lead placement had a higher HR (HR: 2.67) for LV dysfunction but was not statistically significant (P = 0.2).

CONCLUSION

DDD pacing increases LV dysfunction risk compared with VVI in infants with CCAVB. Single-chamber LV apical pacing should be considered in infants with isolated CCAVB who require pacing. There is a high risk of pacing-related complications, particularly with an increased risk of ventricular lead complications in low-weight neonates.

Transcoronary study of biomarkers in patients with heart failure: Insights into intracardiac production

AIMS

Biomarkers are pivotal in the management of heart failure (HF); however, their lack of cardiac specificity could limit clinical utility. This study aimed to investigate the transcoronary changes and intracardiac production of these biomarkers.

METHODS

Transcoronary gradients for B-type natriuretic peptide (BNP) and five novel biomarkers-galectin-3 (Gal-3), soluble suppression of tumourigenicity 2 (sST2), tissue inhibitor of metalloproteinase 1 (TIMP-1), growth differentiation factor 15 (GDF-15) and myeloperoxidase (MPO)-were determined using femoral artery (FA) and coronary sinus (CS) samples from 30 HF patients and 10 non-HF controls. Intracardiac biomarker production was assessed in an HF canine model using real-time quantitative PCR (qPCR) and western blot (WB) analysis.

RESULTS

Compared with the control group, levels of all detected biomarkers were significantly elevated in the HF group, while transcoronary gradients were only observed for BNP, Gal-3 and TIMP-1 levels in the HF group (BNP: FA: 841.5 ± 727.2 ng/mL vs. CS: 1132.0 ± 959.1 ng/mL, P = 0.005; Gal-3: FA: 9.5 ± 3.0 ng/mL vs. CS: 19.7 ± 16.4 ng/mL, P = 0.002; and TIMP-1: FA: 286.7 ± 68.9 ng/mL vs. CS: 377.3 ± 108.9 ng/mL, P = 0.001). Real-time qPCR and WB analysis revealed significant elevation of BNP, Gal-3 and TIMP-1 in the cardiac tissues of the HF group relative to other groups.

CONCLUSIONS

This study provided evidence of transcoronary changes in BNP, Gal-3 and TIMP-1 levels in HF patients, offering insights into their intracardiac production. These findings enhance the understanding of the biology of these biomarkers and may inform their clinical application.

Cardiac Resynchronization Therapy for Pacing-Related Dysfunction Post Cardiac Surgery in Neonates

An infant with DiGeorge syndrome, multiple comorbidities, and truncus arteriosus type II underwent repair complicated by heart block necessitating placement of a dual-chamber bipolar pacing system with right ventricular leads and subsequent resynchronization with placement of left ventricular apical pacing leads. Resynchronization therapy improved QRS duration from 180 ms to 100 ms and ejection fraction from 25% to 54% over the course of 4 weeks with gradual return to normal function and eventual discharge.

Conduction System Pacing in Children and Congenital Heart Disease

Permanent cardiac pacing in children with congenital complete atrioventricular block (CCAVB) and/or congenital heart disease (CHD) is challenging. Conduction system pacing (CSP) represents a novel pacing strategy aiming to preserve physiological ventricular activation. Patients with CCAVB or CHD are at high risk of developing pacing-induced cardiomyopathy with chronic conventional right ventricular myocardial pacing. CSP may be a valuable pacing modality in this particular setting because it can preserve ventricular synchrony. In this review, we summarise implantation techniques, the available clinical evidence and future directions related to CSP in CCAVB and CHD.

Longitudinal echocardiographic parameters before and after pacemaker placement in congenital complete heart block

BACKGROUND

Congenital complete heart block (CCHB) is seen in 1:15,000-1:20,000 live births, with risk of left ventricular (LV) dysfunction or dilated cardiomyopathy in 7%-23% of subjects.

OBJECTIVE

The purpose of this study was to investigate serial changes in LV size and systolic function in paced CCHB subjects to examine the effect of time from pacemaker on echocardiographic parameters.

METHODS

Single-center retrospective cohort analysis of paced CCHB subjects was performed. Echocardiographic data were collected before and after pacemaker placement. Linear mixed effect regression of left ventricular end-diastolic dimension (LVEDD) z-score, left ventricular shortening fraction (LVSF), and left ventricular ejection fraction (LVEF) was performed, with slopes compared before and after pacemaker placement.

RESULTS

Of 114 CCHB subjects, 52 had echocardiographic data before and after pacemaker placement. Median age at CCHB diagnosis was 0.6 [interquartile range 0.0-3.5] years; age at pacemaker placement 3.4 [0.5-9.0] years; and pacing duration 10.8 [5.2-13.7] years. Estimated LVEDD z-score was 1.4 at pacemaker placement and decreased -0.08 per year (95% confidence interval [CI] -0.12 to -0.04; P = .002) to 0.2 (95% CI -0.3 to +0.3) 15 years postplacement. Estimated LVSF decreased -1.1% per year (95% CI -1.7% to -0.6%; P <.001) from 6 months prepacemaker placement to 34% (95% CI 32%-37%) 4 years postplacement. There was no significant change in LVSF between 4 and 15 years postplacement. Estimated LVEF did not change significantly after pacemaker placement, with estimated LVEF 59% (95% CI 55%-62%) 15 years postplacement.

CONCLUSION

In 52 paced CCHB subjects, estimated LVEDD z-score decreased significantly after pacemaker placement, and estimated LVSF and LVEF remained within normal limits at 15 years postpacemaker placement.

Postoperative Atrioventricular Block in Pediatric Patients: Impact of Congenital Cardiac Malformations and Medications

Postoperative atrioventricular block may occur after pediatric cardiac surgery. A small proportion of those who develop atrioventricular block will require pacemaker placement. The primary aim of this study was to determine factors associated with postoperative atrioventricular block. Secondary aims included determining factors associated with pacemaker placement in those with atrioventricular block. Data from the PHIS data were utilized to identify patients under 18 years of age who underwent cardiac surgery. Those who did and did not develop atrioventricular block. Univariable analyses and regression analyses were conducted to determine factors associated with postoperative atrioventricular block. Similar analyses were conducted to determine factors associated with pacemaker placement in those with atrioventricular block. A total of 43,716 admissions were identified. Of these, 2093 (5%) developed atrioventricular block and 480 (1% of total admissions) underwent pacemaker placement. Approximately 70% of those with atrioventricular block received steroids but this was not associated with a decrease in pacemaker placement. Risk factors (congenital malformations of the heart, comorbidities, medications) associated with increased risk of atrioventricular block and pacemaker placement were identified. Postoperative atrioventricular block occurred in 5% of pediatric admissions for cardiac surgery. Of these admissions with postoperative atrioventricular block, 23% required pacemaker placement. Isoproterenol and steroids were not associated with a reduction in the likelihood of pacemaker placement.

A Study to Analyse the Feasibility and Effectiveness of Left Bundle Branch Area Pacing Used in Young Children

This study aimed to investigate the feasibility and effectiveness of left bundle branch area pacing (LBBaP) in young children. From September 2020 to May 2021, a total of 31 children (≤ 7 years) with complete atrioventricular block were included. All patients were scheduled to undergo LBBaP. Pacing parameters, and cardiac function and synchrony were evaluated during follow-up. LBBaP succeeded in 21 children (3.3 ± 2.1 years old), with a success rate of 70.9%. LBBaP failed in nine children, who eventually received right ventricular septal pacing (RVSP). The average postoperative QRS duration in patients of LBBaP group was narrower than that of RVSP group: 100.9 ± 9.1 versus 114.2 ± 11.9 ms (P = 0.002). The median follow-up duration was 12 [interquartile range (IQR) 6-15] months. At last time of follow-up, the capture threshold of ventricular electrode in patients of LBBaP group were significantly lower than that of RVSP group (0.70 ± 0.25 versus 1.39 ± 0.94 V, P = 0.011). The echo-left ventricular ejection fraction (LVEF) in patients in the LBBaP group was better than that in the RVSP group (66.1 ± 3.3 versus 63.1 ± 2.2%, P = 0.025). LBBaP can be safely and effectively administered in young children. Satisfactory pacing parameters, and narrow QRS durations were obtained.

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.

Effect of carvedilol versus placebo on cardiac function in anthracycline-exposed survivors of childhood cancer (PREVENT-HF): a randomised, controlled, phase 2b trial

BACKGROUND

Carvedilol improves cardiac function in patients with heart failure but remains untested as cardioprotective therapy in long-term childhood cancer survivors (ie, those who have completed treatment for childhood cancer and are in remission) at risk for heart failure due to high-dose anthracycline exposure. We aimed to evaluate the activity and safety of low-dose carvedilol for heart failure risk reduction in childhood cancer survivors at highest risk for heart failure.

METHODS

PREVENT-HF was a randomised, double-blind, phase 2b trial done at 30 hospitals in the USA and Canada. Patients were eligible if they had any cancer diagnosis that resulted in at least 250 mg/m2 cumulative exposure to anthracycline by age 21 years; completed their cancer treatment at least 2 years previously; an ejection fraction of at least 50% or fractional shortening of at least 25%, or both; and bodyweight of at least 40 kg. Patients were randomly assigned (1:1) with automated computer-generated permuted block randomisation (block size of 4), stratified by age at diagnosis, time since diagnosis, and history of chest-directed radiotherapy, to carvedilol (up-titrated from 3·125 g per day to 12·5 mg per day) or placebo orally for 2 years. Participants, staff, and investigators were masked to study group allocation. The primary endpoint was to establish the effect of carvedilol on standardised left ventricular wall thickness-dimension ratio Z score (LVWT/Dz). Treatment effects were analysed with a linear mixed-effects model for normally distributed data with a linear time effect and testing the significance of treatment*time interaction in the modified intention-to-treat (mITT) cohort (ie, all randomly assigned participants who had a baseline and at least one subsequent echocardiogram measurement). Safety was assessed in the ITT population (ie, all randomly assigned participants). This trial was registered with ClinicalTrials.gov, NCT027175073, and enrolment and follow-up are complete.

FINDINGS

Between July 3, 2012, and June 22, 2020, 196 participants were enrolled, of whom 182 (93%) were eligible and randomly assigned to either carvedilol (n=89) or placebo (n=93; ITT population). Median age was 24·7 years (IQR 19·6-36·6), 91 (50%) participants were female, 91 (50%) were male, and 119 (65%) were non-Hispanic White. As of data cutoff (June 10, 2022), median follow-up was 725 days (IQR 378-730). 151 (n=75 in the carvedilol group and n=76 in the placebo group) of 182 participants were included in the mITT population, among whom LVWT/Dz was similar between the two groups (-0·14 [95% CI -0·43 to 0·16] in the carvedilol group vs -0·45 [-0·77 to -0·13] in the placebo group; difference 0·31 [95% CI -0·10 to 0·73]; p=0·14). Two (2%) of 89 patients in the carvedilol group two adverse events of grade 2 or higher (n=1 shortness of breath and n=1 arthralgia) and none in the placebo group. There were no adverse events of grade 3 or higher and no deaths.

INTERPRETATION

Low-dose carvedilol appears to be safe in long-term childhood cancer survivors at risk for heart failure, but did not result in significant improvement of LVWT/Dz compared with placebo. These results do not support the use of carvedilol for secondary heart failure prevention in anthracycline-exposed childhood cancer survivors.

FUNDING

National Cancer Institute, Leukemia & Lymphoma Society, St Baldrick's Foundation, Altschul Foundation, Rally Foundation, American Lebanese Syrian Associated Charities.

Pacing in Pediatric Patients with Postoperative Atrioventricular Block

Surgery for congenital heart disease may compromise atrioventricular (AV) nodal conduction, potentially resulting in postoperative AV block. In the majority of cases, AV nodal function recovers during the early postoperative period and may only require short-term pacing support, typically provided via temporary epicardial wires. Permanent pacing is indicated when the postoperative AV block persists for more than 7 to 10 days due to the risk of mortality if a pacemaker is not implanted. Although there is a subset of patients who may have late recovery of AV nodal function, those with continued postoperative AV block will need lifelong pacing therapy.

Observations of interventricular septal behavior during left bundle branch pacing

INTRODUCTION

Left bundle branch pacing (LBBP) involves the deployment of the lead deep inside the septum. Penetration of the septum by the lead depends on the texture of the septum, rapidity of rotations, operator experience, and implantation tools.

OBJECTIVES

The aim of our study was to assess the behavior of the lumenless lead during rapid rotations and the physiological property of the interventricular septum(IVS) during LBBP.

METHODS

Patients undergoing LBBP between January 2021 and December 2022 were retrospectively included in the study.

RESULTS

Among 255 attempted patients, 20 (7.9%) had procedural failure(no LBB capture-four, inability to penetrate septum-seven, and dislodgements after sheath removal-nine). Septal penetration achieved in 248/255 patients (97.2%). Lead movement inside the IVS was assessed by lead traverse time. Based on the behavior of the IVS (n = 255), three different responses were noted. Type-I response(normal/firm septum) in 93.7% (n = 239) characterized by constant and progressive movement of lead. Neither perforation nor further change in premature-ventricular-complex morphology beyond M-beat were observed despite additional few unintentional rotations indicating the protective mechanism of LV-endocardium. Type-II response(soft/cheesy septum) in 3.5% (n = 9) characterized by hyper-movement of lead without resistance due to altered texture of septum and poor LV subendocardial barrier resulting in perforation. No patients in this group had LV dysfunction or associated coronary artery disease. In type-III response, seen in 2.8% (n = 7), lead could not be penetrated due to scar in IVS.

CONCLUSION

Three different patterns of responses were observed during LBBP. The most distinct type-ll response was associated with soft/cheesy septum with hyper-movement of the lead predisposing for future dislodgments in patients without structural heart disease.

The estimated glomerular filtration rate predicts pacemaker-induced cardiomyopathy

Clinical predictors for pacemaker-induced cardiomyopathy (PICM) (e.g., a wide QRS duration and left bundle branch block at baseline) have been reported. However, factors involved in the development of PICM in patients with preserved left ventricular ejection fraction (LVEF) remain unknown. This study aimed to determine the risk factors for PICM in patients with preserved LVEF. The data of 113 patients (average age: 71.3 years; men: 54.9%) who had echocardiography before and after pacemaker implantation (PMI) among 465 patients undergoing dual-chamber PMI were retrospectively analyzed. Thirty-three patients were diagnosed with PICM (18.0/100 person-years; 95% CI 12.8-25.2). A univariate Cox regression analysis showed that an estimated glomerular filtration rate (eGFR) ≤ 30 mL/min/1.73 m2 (HR 3.47; 95% CI 1.48-8.16) and a past medical history of coronary artery disease (CAD) (HR 2.76; 95% CI 1.36-5.60) were significantly associated with the onset of PICM. After adjusting for clinical variables, an eGFR ≤ 30 mL/min/1.73 m2 (HR 2.62; 95% CI 1.09-6.29) and a medical history of CAD (HR 2.32; 95% CI 1.13-4.80) were independent risk factors for developing PICM. A medical history of CAD and low eGFR are independent risk factors for PICM in patients with preserved LVEF at baseline. These results could be helpful in predicting a decreased LVEF by ventricular pacing before PMI. Close follow-up by echocardiography is recommended to avoid a delay in upgrading to physiological pacing, such as cardiac resynchronization therapy or conduction system pacing.

Pacing induced cardiomyopathy: recognition and management

Right ventricle (RV) apex continues to remain as the standard pacing site in the ventricle due to ease of implantation, procedural safety and lack of convincing evidence of better clinical outcomes from non-apical pacing sites. Electrical dyssynchrony resulting in abnormal ventricular activation and mechanical dyssynchrony resulting in abnormal ventricular contraction during RV pacing can result in adverse LV remodelling predisposing some patients for recurrent heart failure (HF) hospitalisation, atrial arrhythmias and increased mortality. While there are significant variations in the definition of pacing induced cardiomyopathy (PIC), combining both echocardiographic and clinical features, the most acceptable definition for PIC would be left ventricular ejection fraction (LVEF) of <50%, absolute decline of LVEF by ≥10% and/or new-onset HF symptoms or atrial fibrillation (AF) after pacemaker implantation. Based on the definitions used, the prevalence of PIC varies between 6% and 25% with overall pooled prevalence of 12%. While most patients undergoing RV pacing do not develop PIC, male sex, chronic kidney disease, previous myocardial infarction, pre-existing AF, baseline LVEF, native QRS duration, RV pacing burden, and paced QRS duration are the factors associated with increased risk for PIC. While conduction system pacing (CSP) using His bundle pacing and left bundle branch pacing appear to reduce the risk for PIC compared with RV pacing, both biventricular pacing and CSP may be used to effectively reverse PIC.

The history of cardiac pacing in the young and a look to the future

PURPOSE OF REVIEW

The purpose of this review is to explore the historical and serendipitous events that led to the creation of modern-day pacemakers. In addition, this review will explore how contemporary conduction site-specific pacing has overcome some of the deleterious effects from historical chronic right ventricular apical pacing.

RECENT FINDINGS

Recently, there have been tremendous advances in not just the lead design but the tools required to promote more physiologic pacing. Although cardiac resynchronization pacing has been around for nearly 2 decades, this review also introduces and discusses the early results of His-bundle pacing and left bundle branch pacing and some of the potential applicability of this technology for our children.

SUMMARY

Pacemakers have evolved significantly in the last 30 years through collaborative partnerships between physicians and engineers. The future of cardiac pacing is bright compared to the field of electrotherapy 50 years ago. Future iterations of pacemakers must consider unusual anatomy and growing children. Pediatric patients contribute to a small percentage of the overall device volume, but the majority of these patients will have a pacemaker for life. We need to be proactive and consider what are the best short and long-term solutions for this cohort.

Long term clinical outcomes in patients requiring cardiac pacing due to congenital complete heart block

Background

Isolated congenital complete heart block (CCHB) is rare cardiac condition associated with maternal Anti-Rho antibodies. It is managed with permanent pacemaker insertion. We sought to determine the long-term outcomes of individuals with CCHB who had undergone pacemaker insertion.

Methods

A database search was performed at a UK tertiary cardiac referral centre. The online medical records of patients with CCHB were analysed for pacing requirements and complications, echocardiographic data, and clinical status.

Results

A total of 72 patients (female n = 46) were identified, 20% of whom were autoantibody positive. Mean age of initial implantation was 15.5 years (SD 12.7) with mean follow up of 21 years (SD 8.3). 88% of patients were NYHA class I at censure of data. Major adverse cardiac events (MACE) were observed in 2 patients with 0% mortality throughout the follow up period. 16 patients (22.2%) developed cardiomyopathy, of which 15 had CRT devices inserted.Five patients had device related infections and 7 required system extractions. Mean left ventricular ejection fraction on most recent echocardiogram was 53.7% (SD 8.40) with no significant change compared with their historic scan. Mild tricuspid regurgitation was the most frequently observed valvular pathology, identified in 28% of patients. Only 2 patients (2.7%) had severe valve incompetence but neither required surgical intervention.

Conclusion

Long-term outcomes for patients with congenital complete heart block who undergo pacemaker insertion are highly favourable. Despite high pacing requirements over an extended period, the incidence of MACE and pacing related complications is low. Cardiac function and valvular competence are largely preserved but dilated cardiomyopathy remains a late concern in a minority; ongoing clinical surveillance is paramount in this population.

Novel Radiomics Features for Automated Detection of Cardiac Abnormality in Patients with Pacemaker

Cardiac pacemakers are used in the treatment of patients with symptomatic bradycardia. The pacemaker paces the heart at the predetermined rate to maintain uninterrupted cardiac activity. Usually, pacemaker lead will be connected to the right atrium (RA) and right ventricle (RV) in dual-chamber pacemaker implantation and RV alone in single-chamber pacemaker implantation. This alters the route of proper conduction across the myocardial cells. The cell-to-cell conduction transmission in pacing delays the activation of selected intraventricular myocardial activation. Pacing-induced cardiomyopathy (PICM) is most commonly defined as a drop in left ventricle ejection fraction (LVEF) in the setting of chronic, high-burden right ventricle (RV) pacing. Currently, very few effective treatments are standard for PICM which rely on the detection of the RV pacing. Such treatments have primarily focused on upgrading to cardiac resynchronization therapy (CRT) when LVEF has dropped. However, the early and accurate detection of these stress factors is challenging. Cardiac desynchrony and interventricular desynchrony can be determined by various echocardiographic techniques, including M-mode, Doppler method, tissue Doppler method, and speckle tracking echocardiography which is subjective measures and shows a significant difference between RV and LV preejection period where the activation of LV is delayed considerably. Computer-aided diagnosis (CAD) is a noninvasive technique that can classify the ultrasound images of the heart in pacemaker-implanted patients and healthy patients with normal left ventricular systolic function and further detect the variations in pacemaker functions in its early stage using heart ultrasound images. Developing such a system requires a vast and diverse database to reach optimum performance. This paper proposes a novel CAD tool for the accurate detection of pacemaker variations using machine learning models of decision tree, SVM, random forest, and AdaBoost. The models have been used to extract radiomics features in terms of textures and then screened by their Relief-F scores for selection and ranking to be classified into nine groups consisting of up to 250 radiomics features. Ten best features were fed to the machine learning models. The R-wave dataset achieved a maximum test performance accuracy of 97.73% with four features in the random forest model. The T-wave dataset achieved a maximum test performance accuracy of 96.59% with three features in the SVM model. Our experimental results demonstrate the system's robustness, which can be developed as an early and accurate detection system for pacing-induced cardiomyopathy.

Incidence of Morbidity and Mortality in a Cohort of Congenital Complete Heart Block Patients Followed Over 40 Years

BACKGROUND

Congenital Complete Heart Block (CCHB), seen in 1:15,000-20,000 births, commonly requires pacemaker placement by young adulthood. There is limited understanding of cardiac morbidity and mortality.

OBJECTIVE

Determine long-term incidence of cardiac morbidity and mortality in subjects with CCHB and identify associated risk factors.

METHODS

Retrospective cohort analysis of subjects with CCHB at Children's Hospital of Philadelphia between 1976-2018. The primary outcome is a composite of death, left ventricular systolic dysfunction, heart failure, cardiomyopathy, or cardiac resynchronization therapy (CRT). Cox proportional hazard models assessed independent risk factors for the primary outcome and its components (death, heart failure and/or cardiomyopathy, CRT).

RESULTS

One-hundred-fourteen subjects (58% female, median age at last visit 15.2 years) were included. Eighty-eight (77%) underwent pacemaker implantation, with median age at placement 1.9 years (IQR, 0.1-8.0 years). Twenty-six subjects (23%) reached the primary outcome - 7 (6%) died and 14 (12%) were diagnosed with heart failure and/or cardiomyopathy. Median time from diagnosis to primary outcome was 3.1 years (IQR, 0.0-10.8 years). There were no significant associations between age at diagnosis less than 1-year (hazard ratio [HR]: 1.5, 95% CI 0.6-3.9), fetal diagnosis (HR: 2.3, 0.96-5.6), or maternal antibody positivity (HR: 2.4, 0.9-6.6) and the primary outcome. Fetal diagnosis had a higher associated hazard of heart failure and/or cardiomyopathy (HR: 4.5, 1.3-15.0).

CONCLUSION

In 114 subjects with CCHB, 23% reached the composite outcome of cardiac morbidity and mortality, with no significant association between age at diagnosis, fetal diagnosis, and maternal antibody status with composite cardiac morbidity and mortality.

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.

Angiography-guided mid/high septal implantation of ventricular leads in patients with congenital heart disease

BACKGROUND

Conduction system pacing prevents pacing-induced cardiomyopathy, but it can be challenging to perform in patients with congenital heart disease (CHD), and mid/high septal lead implantation is an alternative. This study aimed to assess intraprocedural angiography's utility as a guide for mid/high-septal lead implantation in CHD patients.

METHODS

The study subjects were CHD patients with Class I/IIa indications for permanent pacemaker implantation. To guide septal lead implantation, we performed an intraprocedural right ventricular angiogram in anteroposterior, 40° left anterior oblique, and 30° right anterior oblique. The primary endpoint was the lead tip in the mid/high septum on computed tomography (CT). The secondary endpoints were complications and systemic ventricular function on follow-up.

RESULTS

From January 2008 to December 2018, we enrolled 27 patients (mean age: 30 ± 20 years; M:F 17:10) with CHD (unoperated: 20, operated: 7). The mean paced QRS duration was 131.7 ± 5.8 ms, and CT done in 22/27 patients confirmed the lead tip in the mid-septum in 16, high septum in 5, and apical septum in 1 patient. There were no procedural complications, and during a mean follow-up of 58 ± 35.2 months, there was no significant change in the systemic ventricular ejection fraction (56.4 ± 8.3% vs 53.9 + 5.9%, P = .08). Two patients with Eisenmenger syndrome died because of refractory heart failure.

CONCLUSIONS

Intraprocedural angiography is safe and useful to guide mid/high-septal lead implantation in CHD patients. Mid/high septal lead position preserves systemic ventricular function in patients with CHD during medium-term follow-up.

2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

2021 PACES Expert Consensus Statement on the Indications and Management of Cardiovascular Implantable Electronic Devices in Pediatric Patients: Developed in collaboration with and endorsed by the Heart Rhythm Society (HRS), the American College of Cardiology (ACC), the American Heart Association (AHA), and the Association for European Paediatric and Congenital Cardiology (AEPC) Endorsed by the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS)

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

2021 PACES Expert Consensus Statement on the Indications and Management of Cardiovascular Implantable Electronic Devices in Pediatric Patients

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consenus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology, (ACC) and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate follow-up in pediatric patients.

Three-dimensional mapping for His-bundle pacing in pediatric patients, a case series

INTRODUCTION

Pediatric patients who receive pacemakers may have a lifetime of repeat exposure to fluoroscopy. His bundle pacing may provide better long-term pacing for these patients. To minimize fluoroscopy and for improved localization of the His bundle, we utilized three-dimensional mapping to guide His bundle pacing and we follow-up short-term results.

METHODS

An Octapolar Livewire catheter (Abbott, Minneapolis, USA) was used for mapping and location of the His bundle while 3-dimensional mapping via the EnSite Precision system (Abbott Medical, Abbott Park, IL) was utilized to create a 3-dimensional geometry. The EnSite Precision system also mapped and recorded His bundle signal strengths and earliest ventricular activation or retrograde His bundle activation.

RESULTS

Three patients are presented and followed for 4-5 months. The ages ranged from 10 to 15 years with 1 male patient. Diagnoses including progressive atrioventricular block, alternating bundle branch block and atrioventricular canal defect with complete heart block. All patients received selective His-bundle pacing systems. The range in fluoroscopy time was 6.4 to 9.9 min with 5.64 mGy to 10.18 mGy. Stable lead thresholds, impedances and sensing were present at last follow-up.

CONCLUSIONS

His bundle pacing in our 3 pediatric patients including one with altered His-bundle physiology (case 3 with atrioventricular canal defect) was successful with good short-term follow-up results.

Permanent His Bundle Pacing in Patients With Congenital Complete Heart Block: A Multicenter Experience

OBJECTIVES

This study retrospectively assessed the safety and efficacy of permanent His bundle pacing (HBP) in patients with congenital complete heart block (CCHB).

BACKGROUND

HBP has become an accepted form of pacing in adults. Its role in CCHB is not known.

METHODS

Seventeen patients with CCHB who underwent successful HBP were analyzed at 6 academic centers between 2016 and 2019. Nine patients had de novo implants, and 8 patients had previous right ventricular (RV) leads. Three RV paced patients had reduced left ventricular ejection fractions at the time of HBP. Implant/follow-up device parameters, New York Heart Association functional class, QRS duration, and left ventricular ejection fraction data were analyzed.

RESULTS

Patients' mean age was 27.4 ± 11.3 years, 59% were women, and mean follow-up was 385 ± 279 days. The following parameters were found to be statistically significant between implant and follow-up, respectively: impedance, 602 ± 173 Ω versus 460 ± 80 Ω (p < 0.001); and New York Heart Association functional class, 1.7 ± 0.9 versus 1.1 ± 0.3 (p = 0.014). In patients with previous RV pacing, HBP resulted in a significant decrease in QRS duration: 167.1 ± 14.3 ms versus 118.3 ± 13.9 ms (p < 0.0001). In de novo implants, HBP resulted in increases in QRS duration compared with baseline: 111.1 ± 19.4 ms versus 91.0 ± 4.8 ms (p = 0.016). Other parameters exhibited no statistically significant differences. During follow-up, 2 patients required lead revision due to elevated pacing thresholds.

CONCLUSIONS

HBP seems to be safe and effective, with improvement in clinical outcomes in patients with CCHB. Larger studies with longer follow-up periods are required to confirm our findings.

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.

Right ventricular septal pacing via transmural approach for resynchronization in a child with postoperative heart block

An infant with transposition of the great arteries was paced for postoperative heart block (single-site, right ventricular [RV] epicardial). She developed severe left ventricular (LV) dysfunction and septal dyskinesis. Resynchronization was performed at the age of 4 with an LV epicardial lead and an RV septal endocardial lead. The endocardial lead was affixed to the interventricular septum, then tunneled through the RV free wall and attached to an abdominal pulse generator. QRS duration decreased (176 to 122 ms) and LV ejection fraction improved (26 to 61%) and remained stable for 8 years. We present a case of successful resynchronization in congenital heart disease using a transmural RV septal lead.

Pacemaker Implantation in Neonates and Infants: Favorable Outcomes with Epicardial Pacing Systems

The implantation of pacemakers (PM) in neonates and infants requires particular consideration of small body size, marked body growth potential, and the decades of future pacing therapy to be expected. The aim of this study is to quantify the complications of implantation and outcome occurring at our center and to compare these with other centers. Retrospective analysis of 52 consecutive patients undergoing PM implantation at a single tertiary care center within the first year of life. PMs were implanted at a median age of 3 months (range 0-10 months). Structural heart defects were present in 44 of 52 patients. During a median follow-up time of 40.4 months (range 0.1-114 months), measurements for sensing, pacing thresholds, and lead impedance remained stable. No adverse pacing effect was observed in left ventricular function or dimensions over time. There were 20 reoperations in 13 patients at a median time of 4.7 years (range 0.05-8.2 years) after implantation, for end of battery life (n = 10), lead dysfunction (n = 3), device dislocation (n = 3), infection (n = 3), and diaphragmatic paresis (n = 1). No PM-related mortality occurred. Epicardial pacemaker implantation in neonates and infants is an invasive but safe and effective procedure with a relatively low risk of complications. Our current implantation technique and the use of bipolar steroid-eluting electrodes, which we prefer to implant on the left ventricular apex, lead to favorable long-term results.

Left ventricular apical pacing in children: feasibility and long-term effect on ventricular function

AIMS

Left ventricular apical pacing (LVAP) has been reported to preserve left ventricular (LV) function in chronically paced children with complete atrioventricular block (CAVB). We sought to evaluate long-term feasibility of LVAP and the effect on LV mechanics and exercise capacity as compared to normal controls.

METHODS AND RESULTS

Thirty-six consecutive paediatric patients with CAVB and LVAP in the absence (N = 22) or presence of repaired structural heart disease (N = 14, systemic LV in all) and 25 age-matched normal controls were cross-sectionally studied after a median of 3.9 (interquartile range 2.1-6.8) years of pacing using echocardiography and exercise stress testing. Pacemaker implantation was uneventful and there was no death. Probability of the absence of pacemaker-related surgical revision (elective generator replacement excluded) was 89.0% at 5 years after implantation. Left ventricular apical pacing patients had lower maximum oxygen uptake (P = 0.009), no septal to lateral but significant apical to basal LV mechanical delay (P < 0.001) which correlated with decreased LV contraction efficiency (P = 0.001). Left ventricular ejection fraction and global longitudinal LV strain were, however, not different from controls. Results were similar in both the presence and absence of structural heart disease.

CONCLUSION

Left ventricular apical pacing is technically feasible with a low reintervention rate. Mechanical synchrony between LV septum and free wall is maintained at the price of an apical to basal mechanical delay associated with LV contraction inefficiency as compared to healthy controls. Global LV systolic function is, however, not negatively affected by LVAP.

Congenital heart block: Pace earlier (Childhood) than later (Adulthood)

Congenital complete heart block (CCHB) occurs in 2-5% of pregnancies with positive anti-Ro/SSA and/or anti-La/SSB antibodies, and has a recurrence rate of 12-25% in a subsequent pregnancy. After trans-placental passage, these autoantibodies attack and destroy the atrioventricular (AV) node in susceptible fetuses with the highest-risk period observed between 16 and 28 weeks' gestational age. Many mothers are asymptomatic carriers, while <1/3 have a preexisting diagnosis of a rheumatic disease. The mortality of CCHB is predominant in utero and in the first months of life, reaching 15-30%. The diagnosis of CCHB can be confirmed by fetal echocardiography before birth and by electrocardiography after birth. Whether early in-utero detection and treatment might prevent or reverse this condition remains controversial. In addition to autoantibody-associated CCHB, there is also an isolated (absent structural heart disease) nonimmune early- or late-onset heart block detected later in childhood that may be associated with specific genetic markers or other pathogenic mechanisms. In isolated immune or non-immune CCHB, cardiac pacemakers are implanted in symptomatic patients, however, data on the natural history of CCHB in the adult life indicate that all patients, even if asymptomatic, should receive a pacemaker when first diagnosed. However, important issues have emerged in these patients wherein life-long conventional right ventricular apical pacing may produce left ventricular dysfunction (pacing-induced cardiomyopathy) necessitating a priori alternate site pacing or subsequent upgrading to biventricular pacing. All these issues are herein reviewed and two algorithms are proposed for diagnosis and management of CCHB in the fetus and in the older individual.

Comorbidity and long-term outcome in patients with congenital heart block and their siblings exposed to Ro/SSA autoantibodies in utero

OBJECTIVE

Congenital heart block (CHB) may develop in fetuses of Ro/SSA autoantibody-positive women. Given the rarity of CHB, information on comorbidity and complications later in life is difficult to systematically collect for large groups of patients. We therefore used nation-wide healthcare registers to investigate comorbidity and outcomes in patients with CHB and their siblings.

METHODS

Data from patients with CHB (n= 119) and their siblings (n= 128), all born to anti-Ro/SSA-positive mothers, and from matched healthy controls (n= 1,190) and their siblings (n= 1,071), were retrieved from the Swedish National Patient Register. Analyses were performed by Cox proportional hazard modelling.

RESULTS

Individuals with CHB had a significantly increased risk of cardiovascular comorbidity, with cardiomyopathy and/or heart failure observed in 20 (16.8%) patients versus 3 (0.3%) controls, yielding a HR of 70.0 (95% CI 20.8 to 235.4), and with a HR for cerebral infarction of 39.9 (95% CI 4.5 to 357.3). Patients with CHB also had a higher risk of infections. Pacemaker treatment was associated with a decreased risk of cerebral infarction but increased risks of cardiomyopathy/heart failure and infection. The risk of systemic connective tissue disorder was also increased in patients with CHB (HR 11.8, 95% CI 4.0 to 11.8), and both patients with CHB and their siblings had an increased risk to develop any of 15 common autoimmune conditions (HR 5.7, 95% CI 2.83 to 11.69 and 3.6, 95% CI 1.7 to 8.0, respectively).

CONCLUSIONS

The data indicate an increased risk of several cardiovascular, infectious and autoimmune diseases in patients with CHB, with the latter risk shared by their siblings.

Biventricular pacing for treating heart failure in children: A case report and review of the literature

BACKGROUND

Cardiac resynchronization therapy (CRT) can be used as an escalated therapy to improve heart function in patients with cardiac dysfunction due to long-term right ventricular pacing. However, guidelines are only targeted at adults. CRT is rarely used in children.

CASE SUMMARY

This case aimed to implement biventricular pacing in one child with heart failure who had a left ventricular ejection fraction < 35% at 4 years after implantation of an atrioventricular sequential pacemaker due to atrioventricular block. Postoperatively, echocardiography showed atrial sensing ventricular pacing and QRS wave duration of 120-130 ms, and cardiac function significantly improved after upgrading pacemaker.

CONCLUSION

Patients whose cardiac function is deteriorated to a level to upgrade to CRT should be upgraded to reverse myocardial remodeling as soon as possible.

Cardiac Resynchronization Therapy in Pediatrics

Cardiac resynchronization therapy (CRT) has proven to be a powerful and effective tool in the treatment of adults with severe dilated or ischemic cardiomyopathy. A substantial portion of the adult heart failure population has severely depressed systolic function, heart failure symptoms, QRS prolongation, and left bundle branch block. Indications for CRT in adults are commonly focused on these characteristics. However, pediatric patients represent a heterogeneous group with many etiologies of heart failure and anatomic variants, with most of them not fitting the typical adult CRT criteria. The heterogeneity of the pediatric population has hindered the identification of ideal candidates for CRT, but initial experience with CRT in various groups of pediatric patients has been encouraging. This article reviews indications for and outcomes of CRT in pediatric and congenital heart disease patients.

The Prevalence of Pacing-Induced Cardiomyopathy (PICM) in Patients With Long Term Right Ventricular Pacing - Is it a Matter Of Definition?

BACKGROUND

Chronic right ventricular pacing may contribute to deterioration in left ventricular ejection fraction (LVEF). The aim of the study was to identify the prevalence of pacing-induced cardiomyopathy (PICM) in patients with chronic right ventricular pacing.

METHODS

Patients attending a pacemaker clinic were retrospectively identified as having had transthoracic echocardiographic LVEF measurement during the 12 months prior to device implantation. Those with cardioverter-defibrillators or biventricular devices were excluded. The remaining patients were invited back for a repeat echocardiogram. Three (3) different definitions of PICM were employed: 1) follow-up LVEF of ≤40% if baseline LVEF was ≥50%, or an absolute reduction in LVEF ≥5% if baseline LVEF was <50%; 2) follow-up LVEF of ≤40% if baseline LVEF was ≥50%, or an absolute reduction in LVEF ≥10% if baseline LVEF was ≤50%; 3) absolute reduction in LVEF ≥10% irrespective of baseline LVEF. Alternate causes of cardiomyopathy were excluded following a chart review.

RESULTS

The study cohort of 118 included 67 males (mean age 77.8±10.5years) and 51 females (mean age 76.8±11.2years). The mean time between baseline and follow-up echocardiograms was 3.5+1.4years (range 1.5-6.4 years). The prevalence of PICM ranged from 5.9 to 39.0% depending on PICM definition. Multivariate analysis found that PICM was significantly associated with ventricular pacing burden (p=0.013).

CONCLUSIONS

The prevalence of pacing induced cardiomyopathy is dependent on current accepted clinical definitions. A clear definition of PICM is required for a better understanding of the clinical implications of right ventricular pacing.

Echocardiographic assessment of ventricular contraction and synchrony in children with isolated complete atrioventricular block and epicardial pacing: Implications of interventricular mechanical delay

AIMS

To assess the correlations between interventricular mechanical delay (IVMD) and cardiac function in children with isolated complete atrioventricular block and epicardial pacing.

METHODS AND RESULTS

We enrolled 13 children (six boys) with an epicardial dual-chamber pacemaker due to isolated complete or advanced atrioventricular block. The patients were 9.8 (range, 6.8-15.3) years old, and none had symptomatic heart failure at the follow-up visit. Ventricular pacing sites, which remained the same for 7.2 (1.6-12.3) years, were the left ventricle (LV) in two patients, right ventricle (RV) in four patients, and both ventricles in seven patients. IVMD was ≤40 ms in six patients (short IVMD group) and >40 ms in seven patients (long IVMD group). Compared with the long IVMD group, the short IVMD group was associated with better LV longitudinal strain (-20% [-24% to -18%] vs -16% [-20% to -13%], P < .05). The short IVMD group had superior LV mechanical synchrony than the long IVMD group (septal to lateral delay of the time to peak longitudinal strain 15 [-16-78] ms vs 78 [13-93] ms, P < .05; standard deviation of the time to peak radial strain 13 [9-34] ms vs 35 [18-64] ms, P < .05).

CONCLUSION

In children with epicardial pacing at LV, RV, or both ventricles, a left-sided contraction delay was associated with poorer LV contraction and impaired LV synchrony. IVMD will help to stratify patients during follow-up.

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.

Successful Treatment of an Infant with Left Ventricular Noncompaction Presenting with Fatal Ventricular Arrhythmia Treated with Cardiac Resynchronization Therapy and an Implantable Cardioverter Defibrillator

We herein report the successful treatment of a 4-year-old girl with left ventricular noncompaction (LVNC) who presented with incessant ventricular fibrillation at 5 months of age. An implantable cardioverter defibrillator (ICD) was implanted, and dual chamber (DDD) pacing was initiated at 7 months of age. At her 10-month follow-up, her left ventricular ejection fraction (LVEF) had decreased from 45% to 20% with mechanical dyssynchrony. After upgrading to cardiac resynchronization therapy (CRT), the LVEF improved to 50%. The usefulness of CRT in pediatric LVNC has not been fully elucidated. However, our case suggests that CRT therapy may be an effective option for LVNC-induced cardiac dysfunction.

What endocardial right ventricular pacing site shows better contractility and synchrony in children and adolescents?

AIMS

Right ventricular (RV) apical (RVA) pacing can induce left ventricular (LV) dyssynchrony, remodeling, and dysfunction in children with complete atrioventricular block (CAVB). We compared the functional outcome of RVA with RV alternative pacing sites (RVAPS), including para-Hisian, septal, and outflow tract sites.

METHODS

This is a single-center, retrospective study. Data were collected before pacemaker implantation (transvenous leads), postoperatively, at 6 months, and at 1-2-3-4 years. Electrocardiogram evaluation included QRS duration, axis, QTc/JTc, and QTc dispersion. Echocardiographic evaluation included 2-D/3-D assessment of ventricular dimensions (Z-score of LV end-diastolic dimension), function (ejection fraction), and synchrony.

RESULTS

From 2009 to 2015, 55 patients with CAVB, aged 3-17 years, with or without other congenital heart defects, underwent RVAPS (30 patients, median age 11 years) or RVA (25 patients, median 12 years). All leads were positioned into the septum. Before implantation, no significant differences in parameters were observed, except for higher Z-score in RVAPS than in RVA. After implantation, at a median follow-up of 2.5 (range 1-6) years, the two groups showed no significant differences in LV dimensions, contractility, and synchrony. QRS intervals of RVAPS were significantly shorter than RVA. Clinical status was good and contractility/synchrony indexes were normal or adequate in all patients.

CONCLUSIONS

In pediatric patients, RVAPS and RVA showed no significant differences in LV dimensions, contractility, and synchrony. Preimplantation dilated patients showed LV reverse remodeling. RVAPS demonstrated shorter QRS intervals. Therefore, septal pacing sites, either RVA or RVAPS, seem to determine good contractility and synchrony at a mid-term follow-up.

Key Role of Pacing Site as Determinant Factor of Exercise Testing Performance in Pediatric Patients with Chronic Ventricular Pacing

Chronic right ventricular (RV) apical pacing has been associated with deterioration of functional capacity and chronotropic incompetence during exercise testing in children. The effects of alternative pacing site on exercise performance in pediatric population remain unknown. We evaluated the influence of ventricular pacing site on exercise capacity in pediatric patients with complete congenital atrioventricular block requiring permanent pacemaker therapy. Sixty-four children paced from RV apex (n = 26), RV midseptum (n = 15) and left ventricular (LV) apex (n = 23) were studied cross-sectionally. Treadmill exercise stress testing was performed according to modified Bruce protocol. LV apical pacing was associated with greater exercise capacity. In comparison with the other study groups, children with RV apical pacing showed significantly lower VO₂peak (37 ± 4.11; p = 0.003), O₂ pulse (8.78 ± 1.15; p = 0.006), metabolic equivalents (7 ± 0.15; p = 0.001) and exercise time (6 ± 3.28; p = 0.03). Worse values in terms of maximum heart rate (139 ± 8.83 bpm; p = 0.008) and chronotropic index (0.6 ± 0.08; p = 0.002) were detected in the RV apical pacing group although maximal effort (respiratory exchange ratio) did not differ among groups (p = 0.216). Pacing from RV apex (odds ratio 9.4; confidence interval 2.5-18.32; Wald 4.91; p = 0.0036) and low peak heart rate achieved (odds ratio 3.66; confidence interval 0.19-7.4; Wald 4.083; p = 0.015) predicted significantly decrease in exercise capacity. Duration of pacing, gender, VVIR mode, baseline heart rate and QRS duration had not significant impact on exercise capacity. The site of ventricular pacing has the major impact on exercise capacity in children requiring permanent pacing. Among the sites assessed, LV apex is related to the better exercise performance.