Physiology of Cardiac Pacing in Children: The Importance of the Ventricular Pacing Site

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

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.

The Current State and Future Potential of Pediatric and Congenital Electrophysiology

Pediatric electrophysiologists specialize in the diagnosis and treatment of rhythm abnormalities in pediatric, congenital heart disease, and inherited arrhythmia syndrome patients. The field originated out of the unique knowledge base that rhythm management in young patients required. In the 1970s, pediatric electrophysiology was recognized as a distinct cardiac subspecialty and it has evolved rapidly since that time. Despite the considerable growth in personnel, technology, and complexity that the field has undergone, further opportunities to progress pediatric electrophysiology exist. In this review, we highlight some of the clinical focus of pediatric and adult congenital electrophysiologists to date and identify areas within this specialty where the pediatric and congenital electrophysiology community could come together in order to drive improvements in rhythm management for patients.

Emergency Pacing via the Umbilical Vein and Subsequent Permanent Pacemaker Implantation in a Neonate

A dying neonate with congenital complete atrioventricular block underwent an emergency temporary pacing via the umbilical vein 1 h after birth. Implantation of a permanent epicardial pacemaker system was performed at the age of 10 days. During the follow-up period of 3 months, the child had been growing well with the VVIR pacemaker.

Pacing device therapy in infants and children: a review

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

Ventricular resynchronization by implementation of direct his bundle pacing in a patient with congenital complete AV block and newly diagnosed cardiomyopathy

Congenital complete atrioventricular block (CCAVB) is usually due to failure of AV nodal conduction with preservation of the His Purkinje system, typically present at birth. While most patients with CCAVB ultimately require pacemaker therapy to restore physiologic heart rates, recent studies have suggested that chronic right ventricular (RV) pacing in patients with CCAVB can have detrimental effects on cardiac structure and function, and may account for a 7-10% incidence of congestive heart failure in these patients. Since the His Purkinje system is preserved in CCAVB, this patient population could be uniquely well served by direct His bundle pacing (DHBP) which would be expected to restore physiologic activation of both ventricles. We present a case of a young woman who presented with RV pacing-induced cardiomyopathy who responded dramatically to DHBP.

Pacemaker upgrade causing new-onset heart failure in a patient with complete congenital atrioventricular block

For infants with congenital complete atrioventricular block (CCAVB), the choice of pacing modalities is limited. Due to their size and surgical limitations, neonates typically start with an epicardial right ventricular pacing system, then upgrade to right-sided dual-chamber pacing once appropriate size is achieved. These modes are generally well tolerated. However, the reported case involved a patient with CCAVB who paradoxically experienced congestive heart failure after upgrading to a dual-chamber system, a theoretically superior pacing modality. With conversion to biventricular pacing, a relatively new modality for adults with very little pediatric experience to date, the patient's symptoms dramatically improved.

Survival analysis in patients with preserved left ventricular function and standard indications for permanent cardiac pacing randomized to right ventricular apical or septal outflow tract pacing

BACKGROUND

Optimal right ventricular (RV) pacing site in patients referred for permanent cardiac pacing remains controversial. A prospective randomized trial was done to compare long-term effect of permanent RV apex (RVA) vs RV outflow tract (RVOT) pacing on the all-cause and cardiovascular mortality.

METHODS AND RESULTS

A total of 122 consecutive patients (70 men, 69 +/-11 years), with standard pacing indications were randomized to RVA (66 patients) or RVOT (56 patients) ventricular lead placement. After the 10-year follow-up period the mortality data were summarized on the basis of an intention-to-treat analysis. During the long-term follow-up, 31 patients from the RVA group died vs 24 patients in the RVOT group (hazard ratio (HR), 0.96; 95% confidence interval (CI), 0.57-1.65; P=0.89). There were 10 cardiovascular deaths in the RVA and 12 in the RVOT group (HR, 1.04; 95%CI, 0.45-2.41; P=0.93). There were no differences in the all-cause or cardiovascular mortality between the pacing sites after adjustment for age, gender, arterial hypertension, atrial fibrillation, New York Heart Association class and left ventricular end-diastolic diameter.

CONCLUSIONS

The RVOT provides no additional benefit in terms of long-term survival over RVA pacing.