Dual-chamber epicardial pacing in preterm and low birth weight infants with congenital complete atrioventricular block: a staged approach

Abstract

Background

Congenital complete atrioventricular block (CCAVB) in preterm low birth weight neonates poses significant technical challenges for permanent pacemaker implantation. Epicardial pacing is generally preferred in this population; however, definitive implantation in infants weighing < 2500 g may be technically demanding. We evaluated the feasibility and safety of dual-chamber epicardial pacing in preterm low birth weight neonates with autoimmune-associated CCAVB.

Methods

Eight preterm neonates weighing < 2500 g underwent epicardial pacing between April 2021 and May 2022. All patients initially received temporary epicardial pacing via a subxiphoid approach for rhythm stabilization. Permanent dual-chamber epicardial pacemaker implantation was subsequently performed following clinical optimization and weight gain. Procedural outcomes, pacing performance, ventricular function, and device-related complications were analyzed descriptively.

Results

Temporary pacing was successfully established in all patients at a median postnatal age of 3 days (range, 0–12 days) and a median body weight of 2290 g (range, 1890–2440 g), without major complications. Permanent dual-chamber implantation was achieved in all cases at a median age of 18 days and a mean body weight of 2725 g. Electrical parameters, including sensing amplitudes and capture thresholds, remained stable throughout follow-up. One patient required ventricular lead repositioning due to persistent ventricular dysfunction, with subsequent functional improvement, while ventricular function remained stable or improved in the remaining patients. No device-related complications were observed during the follow-up period. The median follow-up duration was 24 months.

Conclusions

This study indicates that dual-chamber epicardial pacing is feasible and safe in selected preterm low birth weight neonates with CCAVB. When immediate permanent implantation is technically challenging, a staged approach may facilitate stabilization and subsequent definitive implantation with favorable early to short-term outcomes.

Introduction

Congenital complete atrioventricular block (CCAVB) is a rare but clinically significant disorder diagnosed in utero or early life, with an estimated prevalence of approximately 1 in 15,000 live births [1, 2]. In most cases, it is associated with transplacental passage of maternal anti-Ro/SSA or anti-La/SSB antibodies, resulting in immune-mediated injury of the fetal conduction system [3–5].

The clinical course of CCAVB is variable, ranging from asymptomatic bradycardia to severe hemodynamic compromise. Risk factors for adverse outcomes include fetal hydrops, low ventricular escape rates, prematurity, and low birth weight [6–8]. Early rhythm stabilization is therefore essential in symptomatic patients [3, 9].

Permanent pacemaker implantation is the definitive treatment; however, optimal timing, pacing mode, and device configuration in neonates remain incompletely defined, particularly in preterm low birth weight infants [10–12]. In this population, procedural risks are amplified due to small body size, tissue fragility, and limited physiological reserve [12].

Epicardial pacing is generally preferred in this age group; however, permanent implantation in infants weighing less than 2500 g remains technically challenging. In this context, a staged approach—consisting of initial temporary pacing followed by delayed permanent implantation after clinical stabilization and somatic growth—may represent a practical strategy when immediate implantation is not feasible [9, 12].

Despite this, data specifically addressing staged pacing strategies in preterm low birth weight infants remain limited. Therefore, this study aimed to evaluate the feasibility and safety of dual-chamber epicardial pacing using a staged approach in this high-risk population.

Materials and methods

Study design and patient selection

This retrospective observational study was conducted at a tertiary referral center and approved by the Institutional Review Board (Approval No: 462; July 14, 2023). The study was performed in accordance with the principles of the Declaration of Helsinki. Written informed consent for surgical procedures was obtained from the parents or legal guardians of all patients.

Preterm neonates diagnosed with congenital complete atrioventricular block (CCAVB) who required pacing support between April 2021 and May 2022 were reviewed. Inclusion criteria were: [1] prematurity [2], birth weight < 2500 g at the time of initial pacing intervention, and [3] hemodynamically significant bradycardia requiring urgent pacing support. Neonates weighing ≥ 2500 g at the time of initial intervention were excluded to maintain a homogeneous low birth weight study population.

Eight consecutive patients met the inclusion criteria. The decision to initiate temporary epicardial pacing was based on a combination of heart rate, hemodynamic instability, and clinical signs of low cardiac output, rather than a strict heart rate threshold alone. Although guideline recommendations suggest a ventricular rate ≤ 50 beats per minute as an indication for pacing, clinical and hemodynamic factors were also considered in decision-making. In our practice, a pragmatic threshold of approximately 50–55 beats per minute was used in conjunction with clinical findings.

Heart rate values presented in Table 1 represent the mean ventricular rate recorded prior to temporary pacemaker implantation.

Table 1.

Baseline clinical characteristics, pacing indications, and perioperative data of the study population

Pt	GA (wk)	HR (bpm)	HF	SVEF1 (%)	Indication	Age tPMI (d)	Wt tPMI (g)	Age pPMI (d)	Wt pPMI (g)	SVEF2 (%)	Associated cardiac findings	Maternal autoimmune disease
1	28	55	No	62	Bradycardia	3	1890	10	2200	65	PFO, PDA	Sjögren’s syndrome
2	29	52	No	60	Bradycardia	1	2180	54	3000	60	DORV with mitral atresia	SLE
3	31	50	No	58	Bradycardia	0	2300	10	2520	65	PDA	SLE
4	29	48	Yes	30	Bradycardia, clinical signs of low cardiac output	7	2410	18	2725	30*	PFO	Sjögren’s syndrome
5	32	49	Yes	40	Bradycardia, clinical signs of low cardiac output	4	2325	11	2560	57	PFO, PDA	SLE
6	30	50	No	60	Bradycardia	12	2440	29	2930	65	PFO, PDA	SLE
7	28	54	No	55	Bradycardia	1	2310	31	2820	55	PFO, PDA	SLE
8	28	54	No	65	Bradycardia	5	2270	68	3710	65	Tricuspid atresia (Type Ic)	Sjögren’s syndrome
Mean ± SD	29.3 ± 1.5	51.5 ± 2.6	–	58 ± 12	–	–	2300 ± 171	–	2725 ± 445	60 ± 12	–	–

* In Patient 4, the initial ventricular function remained impaired after right ventricular pacing (SVEF ~ 30%). Following surgical revision and relocation of the ventricular epicardial lead from the right ventricle to the left ventricle, ventricular function improved significantly to approximately 60–65% on follow-up echocardiography

Abbreviations: GA: gestational age; HF: heart failure; HR: heart rate; PDA: patent ductus arteriosus; PFO: patent foramen ovale; pPMI: permanent pacemaker implantation; SLE: systemic lupus erythematosus; SVEF1: systemic ventricular ejection fraction prior to pacing; SVEF2: systemic ventricular ejection fraction after permanent implantation; tPMI: temporary pacemaker implantation

Hemodynamically significant bradycardia was defined by clinical evidence of impaired perfusion, including decreased urine output, fluid retention, and laboratory indicators of end-organ hypoperfusion. The designation of heart failure was based on the overall clinical condition rather than ejection fraction alone.

A staged pacing strategy was adopted in all patients. Initial temporary epicardial pacing was performed to provide rhythm stabilization and allow time for clinical optimization, somatic growth, and planning of definitive device implantation.

Sinus node function was assessed based on electrocardiographic evidence of preserved atrial activity with atrioventricular dissociation. In patients with preserved sinus rhythm, dual-chamber pacing was preferred to maintain atrioventricular synchrony and optimize ventricular filling.

Surgical technique

Temporary epicardial pacing

Temporary epicardial pacing was performed under general anesthesia via a limited subxiphoid approach. A 2–3 cm incision was created, and the pericardium was opened in an inverted Y configuration. Exposure of the right atrial appendage was facilitated using a suspension suture.

Temporary epicardial pacing wires (DOPACE temporary pacemaker wire, TPW, Dogsan, Turkey) were secured to the ventricular myocardium using 7−0 polypropylene sutures at two fixation points to reduce the risk of displacement. In selected patients with preserved intrinsic atrial activity, a temporary atrial lead was additionally placed to allow atrioventricular sequential pacing and support hemodynamic stability.

Pacing was initiated modestly above the intrinsic escape rhythm, with gradual rate adjustments guided by blood pressure, clinical perfusion parameters, metabolic status, and echocardiographic findings. This approach was intended to facilitate hemodynamic adaptation and avoid intolerance to abrupt rate changes.

Permanent epicardial pacemaker implantation

Permanent epicardial pacemaker implantation was performed after clinical stabilization and confirmation of ongoing pacing requirement, once appropriate epicardial pacing systems became available. The timing of implantation was not based on a strict weight or gestational age threshold. Although a target body weight of approximately 2500 g was generally preferred, this was not considered an absolute criterion. Instead, decisions were individualized based on clinical status, pacing dependency, and device availability, using a multidisciplinary approach involving pediatric cardiology and cardiac surgery.

Definitive implantation was performed via median sternotomy, extending the previous subxiphoid incision to allow adequate exposure for lead placement. Steroid-eluting bipolar epicardial atrial and ventricular leads (CapSure Epi 4968, Medtronic, Minneapolis, MN, USA) were positioned at sites demonstrating optimal sensing amplitudes and capture thresholds. Intraoperative measurements of sensing, impedance, and capture threshold were recorded prior to final lead fixation.

To accommodate anticipated somatic growth, excess lead length was secured within the pericardial space, and additional slack was coiled beneath the pulse generator within the abdominal pocket. The dual-chamber pulse generator (Vitatron G70 A2 DR MRI SureScan) was implanted in the left upper abdominal quadrant anterior to the posterior rectus sheath. Device selection was based on availability and institutional experience, as device dimensions are comparable to other contemporary dual-chamber systems.

Ventricular lead positioning was individualized according to cardiac anatomy and intraoperative electrical parameters. Leads were placed on the right ventricular outflow tract, left ventricular epicardium, or systemic ventricle in patients with single-ventricle physiology. The operative steps and generator placement within the abdominal pocket are illustrated in Fig. 1.

Fig. 1.

Surgical stages of staged dual-chamber epicardial pacemaker implantation. a) Exposure achieved via median sternotomy with creation of an upper abdominal paramedian pocket for pulse generator placement. b) Bipolar epicardial atrial and ventricular pacing leads secured to the myocardium. c) Final positioning of the pulse generator between the rectus abdominis muscle and the posterior rectus sheath

Assessment of ventricular function

Ventricular systolic function was assessed using echocardiographic ejection fraction measurements. Left ventricular ejection fraction (LVEF) was recorded in patients with biventricular physiology, and systemic ventricular ejection fraction (SVEF) in those with single-ventricle anatomy. Baseline and follow-up measurements were evaluated descriptively.

Statistical analysis

Given the small sample size, data analysis was limited to descriptive statistics. Continuous variables are presented as mean ± standard deviation or median with range, as appropriate, and categorical variables as counts and percentages. No inferential statistical analyses were performed, and the findings should be interpreted descriptively.

Results

The study population consisted of eight preterm neonates, including five males and three females. Hemodynamically significant bradycardia with a ventricular rate below 55 beats per minute was the primary indication for pacemaker implantation in six patients, while two patients presented with bradycardia accompanied by clinical signs of heart failure. Indications for pacing and timing of interventions are summarized in Table 1.

Prenatal diagnosis of congenital complete atrioventricular block was established in five patients, whereas three were diagnosed postnatally. All mothers had documented autoimmune disease, including systemic lupus erythematosus in five cases and Sjögren’s syndrome in three cases.

Two patients had single-ventricle physiology (double-outlet right ventricle with mitral atresia, and tricuspid atresia [Type Ic] with right ventricular hypoplasia). In these patients, ventricular epicardial leads were positioned on the systemic ventricle. The remaining six patients had patent foramen ovale and/or patent ductus arteriosus without major additional cardiac anomalies.

All patients initially underwent temporary epicardial pacing followed by permanent dual-chamber epicardial pacemaker implantation after clinical stabilization and weight gain. During temporary pacing, ventricular rates were adjusted to approximate physiological heart rates (≥ 120 beats per minute), with achieved rates ranging from 128 to 152 beats per minute. Similar heart rate ranges were maintained after permanent implantation under atrial-sensed, ventricular-paced mode.

Several patients underwent additional interventions for patent ductus arteriosus. Surgical PDA ligation was performed at the time of permanent pacemaker implantation in five patients, while one patient underwent transcatheter PDA stent placement prior to permanent implantation.

The mean gestational age was 29 weeks (range, 28–32 weeks). Mean body weight at temporary pacing was 2270 g (range, 1890–2440 g). The median postnatal age at permanent implantation was 18 days (range, 10–68 days), with a mean body weight of 2725 g (range, 2200–3710 g). The lowest body weight at permanent implantation was 2200 g. At the time of permanent pacemaker implantation, postmenstrual age ranged from approximately 29 to 38 weeks.

In the initial cases, ventricular leads were positioned on the right ventricular outflow tract. One patient required reoperation 10 days after implantation due to persistent heart failure, and the ventricular lead was repositioned to the left ventricle, resulting in improvement in ventricular function. Following this experience, ventricular leads were preferentially positioned on the left ventricle in biventricular physiology and on the systemic ventricle in univentricular anatomy. No consistent difference in short-term ventricular function was observed between different ventricular lead positions.

Representative postoperative chest radiographs demonstrating lead configuration and generator position are shown in Fig. 2. Atrial and ventricular sensing amplitudes and capture thresholds are summarized in Table 2. Mean atrial sensing amplitude was 3.1 ± 1.4 mV, and mean atrial capture threshold was 0.8 ± 0.1 V. Mean ventricular sensing amplitude was 9.7 ± 1.7 mV, and mean ventricular capture threshold was 1.2 ± 0.4 V. Pacing parameters remained stable during follow-up.

Fig. 2.

Sequential postoperative chest radiographs of Patient 4. (a) After temporary epicardial pacemaker implantation. (b) After dual-chamber permanent epicardial pacemaker implantation. (c) Following surgical revision of the ventricular lead from the right ventricle to the left ventricle due to persistent postoperative heart failure.

Table 2.

Pacemaker characteristics and pacing parameters

Pt	Generator	A lead¹	V lead¹	Ventricular position	P wave (mV)	Atrial threshold (V @ ms)	R wave (mV)	Ventricular threshold (V @ ms)	AS/VP (%)	AP/VP (%)
1	Vitatron	4968-35	4968-25	RV	2.0	0.7@0.5	7.9	0.8@0.4	100	0
2	Vitatron	4968-35	4968-25	RV	2.3	0.7@0.4	11	0.9@0.4	92	8
3	Vitatron	4968-35	4968-25	RV	3.1	0.9@0.5	10	1.1@0.4	100	0
4	Vitatron	4968-35	4968-25	RV → LV²	2.5	0.8@0.4	6.8	0.6@0.5	80	20
5	Vitatron	4968-35	4968-25	LV	5.9	1.1@0.5	10.5	1.9@0.5	75	25
6	Vitatron	4968-35	4968-25	LV	1.9	0.7@0.4	11	1.6@0.5	100	0
7	Vitatron	4968-35	4968-25	LV	2.3	0.7@0.5	8.9	1.5@0.5	90	10
8	Vitatron	4968-35	4968-25	LV	4.7	1.0@0.4	12	1.0@0.5	82	18
Mean ± SD	–	–	–	–	3.1 ± 1.4	0.8 ± 0.1	9.7 ± 1.7	1.2 ± 0.4	–	–

¹ CapSure Epi 4968, steroid-eluting bipolar epicardial pacing lead (Medtronic, Minneapolis, MN, USA)

² In Patient 4, persistent postoperative heart failure necessitated relocation of the ventricular lead from the right ventricle to the left ventricle

Abbreviations: AP: atrial pacing; AS: atrial sensed; LV: left ventricle; RV: right ventricle; VP: ventricular pacing

In patients with more complex cardiac anatomy, including univentricular physiology, the interval to permanent implantation was longer due to the need for prolonged clinical stabilization and variability in device availability.

The median follow-up duration was 24 months (range, 19–40 months). No mortality occurred during follow-up, and no patient required pulse generator replacement.

No clear decline in ventricular systolic function was observed during the available follow-up period. Two patients presenting with clinical signs of low cardiac output demonstrated improvement in ventricular function after pacing. In one patient, ventricular function improved from 40% to 57%. In another, initial right ventricular pacing was associated with persistent dysfunction (EF ~ 30%); after lead repositioning to the left ventricle, ventricular function improved to approximately 60–65% on follow-up echocardiography.

Temporary pacing wires were removed on the first postoperative day without complications. No major device-related perioperative complications, infections, or lead fractures were observed. One patient developed a superficial wound complication that resolved with conservative management.

In a small number of patients, enteral feeding advancement was associated with a brief extension of total parenteral nutrition; however, no persistent feeding intolerance or major gastrointestinal complications related to abdominal generator placement were observed.

Discussion

Congenital complete atrioventricular block (CCAVB) remains a rare but clinically significant condition in neonates, particularly when associated with maternal autoimmune disease and prematurity [3–5]. Management is especially challenging in preterm low birth weight infants, in whom limited physiological reserve and small body size increase the technical complexity of permanent pacemaker implantation [10, 12]. In this context, the present case series evaluates a staged dual-chamber epicardial pacing strategy and reports descriptive early to short-term outcomes.

Permanent pacemaker implantation in neonates weighing less than 2500 g presents well-recognized difficulties [9, 12]. Transvenous systems are generally avoided due to small vessel size and the risk of thrombosis and vascular obstruction [13, 14]. Consequently, epicardial pacing remains the preferred approach in this population [12, 15–19]. However, immediate permanent implantation in extremely small infants may be technically demanding. In this setting, a staged strategy—consisting of initial temporary pacing followed by delayed permanent implantation—allows for clinical stabilization, somatic growth, and procedural planning.

Recent reports have described the use of miniaturized pacemaker systems enabling early implantation in very small infants. However, these devices are limited to single-chamber pacing and do not preserve atrioventricular synchrony. In contrast, the present study focused on a dual-chamber epicardial approach to maintain atrioventricular synchrony and support ventricular filling, particularly in patients with preserved sinus activity. The choice between these approaches may depend on institutional resources, device availability, and patient-specific factors.

In this case series, the timing of permanent implantation was individualized rather than based on a strict weight threshold, reflecting a balance between clinical stabilization, pacing dependency, and device availability. In addition, the duration of temporary pacing was influenced not only by clinical factors but also by variability in device availability, including disruptions during the COVID-19 pandemic.

Although staged pacing strategies have been previously described [12, 16], data focusing specifically on preterm low birth weight neonates remain limited. This series adds to the existing literature by providing a consistent management strategy, uniform pacing mode selection, and structured follow-up of pacing parameters and ventricular function.

Preservation of atrioventricular synchrony was a central consideration in this study. While robust comparative data are lacking, atrioventricular synchrony is generally considered beneficial for optimizing ventricular filling and cardiac output [9, 20, 21]. In this series, pacing parameters remained stable, and no consistent deterioration in ventricular systolic function was observed during follow-up, although long-term studies have reported an association between chronic pacing and ventricular dysfunction in pediatric patients [22].

It should be noted that improvement in ventricular function may partly reflect heart rate normalization rather than pacing mode alone. In addition, assessment of ventricular function using ejection fraction may be limited in patients with systemic right ventricular physiology. Furthermore, long-term studies have suggested that chronic ventricular pacing may be associated with the development of ventricular dysfunction and late-onset cardiomyopathy over time [23, 24].

Ventricular lead position represents an important technical consideration. Chronic right ventricular pacing, particularly from non-physiological activation sites, has been associated with ventricular dyssynchrony and may contribute to adverse ventricular remodeling and functional deterioration [25–27]. In contrast, pacing from the systemic or left ventricle has been suggested to better preserve ventricular synchrony and function [28, 29]. Alternative physiological pacing strategies, such as His-bundle pacing, have also been explored to maintain more natural ventricular activation, although their application in very low birth weight neonates remains limited [30]. In this series, one patient with persistent dysfunction following right ventricular pacing demonstrated improvement after lead repositioning to the systemic ventricle. Although causality cannot be established in a small case series, this observation supports an individualized approach to lead positioning, guided by both anatomical and functional considerations.

Device-related morbidity was low in this case series. No lead fractures, generator complications, or deep infections were observed during follow-up, and pacing parameters remained stable. While dual-chamber systems may increase procedural complexity, these findings suggest that such an approach can be implemented safely in selected patients when meticulous surgical technique is applied.

Limitations

This study has several limitations. First, the retrospective design and small sample size reflect the rarity of congenital complete atrioventricular block requiring pacing in preterm low birth weight neonates; therefore, the findings should be interpreted as descriptive rather than definitive.

Second, this is a single-center experience, and patient management was influenced by institutional practices and surgeon preference, which may limit external generalizability.

In addition, the study period partially coincided with the COVID-19 pandemic, during which logistical constraints related to device availability may have influenced the timing of permanent pacemaker implantation in selected cases.

Third, the absence of a comparison group precludes evaluation of alternative pacing strategies, and no inferential statistical analyses were performed.

Fourth, ventricular function assessment was based on conventional echocardiographic parameters, and advanced imaging modalities were not systematically used; therefore, subtle dyssynchrony or remodeling may not have been detected.

Finally, follow-up primarily reflects early outcomes. Long-term pacing performance, lead durability, and ventricular remodeling require further evaluation in larger studies.

Conclusions

Permanent pacing remains the definitive therapy for congenital complete atrioventricular block in neonates. In preterm low birth weight patients, epicardial systems represent an anatomically appropriate and widely used approach.

When immediate permanent implantation is not feasible due to limited body size and physiological fragility, a staged strategy consisting of temporary epicardial pacing followed by delayed permanent dual-chamber implantation may facilitate clinical stabilization and subsequent definitive device placement.

In this case series, the staged approach was associated with stable pacing parameters and absence of major device-related complications during short-term follow-up. These findings should be interpreted cautiously but suggest that a structured, stepwise pacing strategy may be feasible in carefully selected patients.

Author contributions

A.I. conceived and designed the study, performed surgical procedures, collected clinical data, and drafted the manuscript. Y.K. and O.D. contributed to data collection, perioperative management, and manuscript revision. H.B. contributed to patient selection, cardiology follow-up, and interpretation of echocardiographic data. All authors reviewed, critically revised, and approved the final version of the manuscript.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was approved by the Institutional Review Board of Gazi Yaşargil Training and Research Hospital (Approval No. 462; July 14, 2023) and conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from the parents or legal guardians of all patients.

Competing interests

The authors declare no competing interests.

Conflict of interest

The authors declare that they have no conflicts of interest.