Pacemaker Syndrome in the Young:. Do Children Need Dual Chamber as the Initial Pacing Mode?

Congenital Heart Block

Congenital complete heart block (CCHB) defines atrioventricular conduction abnormalities diagnosed in utero or within the first 27 days of life. Maternal autoimmune disease and congenital heart defects are most commonly responsible. Recent genetic discoveries have highlighted our understanding of the underlying mechanism. Hydroxychloroquine shows promise in preventing autoimmune CCHB. Patients may develop symptomatic bradycardia and cardiomyopathy. The presence of these and other specific findings warrants placement of a permanent pacemaker to relieve symptoms and prevent catastrophic events. The mechanisms, natural history, evaluation, and treatment of patients with or at risk for CCHB are reviewed.

His Bundle pacing for congenital complete AV block: An attempt to fix a broken heart?

Congenital complete atrioventricular block (CCAVB) is usually due to failure of atrioventricular nodal conduction with preservation of the His‐Purkinje system. Most patients with CCAVB ultimately require pacemaker therapy to restore physiologic heart rates, dealing with the detrimental effects of chronic right ventricular (RV) pacing on cardiac structure and function. The ideal stimulation pattern aims to mimic the normal conduction to restore electromechanical coupling, preventing the harmful effects of lack of atrioventricular and inter‐intraventricular synchrony. This can be done through conduction system pacing. Using His bundle pacing (HBP) for cardiac resynchronization therapy in two complete congenital atrioventricular block patients, we have reported better exercise tolerance and echocardiographic improvements related to reversible left ventricular dysfunction that can be corrected by restoration of the normal activation pathway via the His‐Purkinje network.

Congenital Heart Block

Congenital complete heart block (CCHB) defines atrioventricular conduction abnormalities diagnosed in utero or within the first 27 days of life. Maternal autoimmune disease and congenital heart defects are most commonly responsible. Recent genetic discoveries have highlighted our understanding of the underlying mechanism. Hydroxychloroquine shows promise in preventing autoimmune CCHB. Patients may develop symptomatic bradycardia and cardiomyopathy. The presence of these and other specific findings warrants placement of a permanent pacemaker to relieve symptoms and prevent catastrophic events. The mechanisms, natural history, evaluation, and treatment of patients with or at risk for CCHB are reviewed.

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.

Permanent epicardial pacing in children: long-term results and factors modifying outcome

AIMS

To evaluate the results of permanent epicardial pacing in children.

METHODS AND RESULTS

All consecutive patients from one country (n = 119, period 1977-2009) undergoing permanent epicardial pacemaker implantation at <18 years of age (median 1.8 years, inter-quartile range 0.3-6.4 years) were studied retrospectively. Median patient follow up was 6.4 years (inter-quartile range 2.9-11.1 years); 207 generators, 89 atrial and 153 ventricular pacing leads were implanted. The probability of absence of any pacing system dysfunction was 70.1 and 47.2% at 5 and 10 years after implantation, respectively. Overall probability of continued epicardial pacing was 92.8 and 76.1% at 5 and 10 years, respectively, and increased in the recent implantation era (post-2000, P = 0.04). The use of steroid-eluting leads decreased the risk of exit block with a hazard ratio (HR) of 0.20 [95% confidence interval (CI) 0.09-0.44, P < 0.001)]. The use of bipolar Medtronic 4968 leads reduced the risk of surgical reintervention because of fracture, insulation break, outgrowth or exit block in comparison to the unipolar 4965 lead design (HR 0.12, 95% CI 0.04-0.40, P < 0.001). The AutoCapture™ feature (HR 0.08, 95% CI 0.02-0.36, P < 0.001) and steroid-eluting leads (HR 0.30, 95% CI 0.11-0.84, P = 0.021) decreased the risk of battery depletion.

CONCLUSION

The probability of continued epicardial pacing in children was 76% at 10 years after implantation, increased for implantation in recent years, and allowed transvenous pacing to be deferred to a significantly greater age. The use of bipolar steroid-eluting leads and of a beat-to-beat capture tracking feature significantly increased pacing system longevity and decreased the need for surgical reinterventions.

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

BACKGROUND

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

OBJECTIVE

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Medium-term follow-up and modes of failure following epicardial pacemaker implantation in young children

AIMS

Young children suffering from congenital or post-operative AV-block require life-long pacemaker stimulation. Due to the anatomical prerequisites initially epicardial electrodes are implanted and the generator is placed in the upper abdominal wall. The following study investigated modes of failure leading to reoperation in this group of technically challenging patients.

METHODS AND RESULTS

Between October 2000 and May 2005, a total of 21 infants (age 3 days to 5 years) underwent pacemaker implantation using a subxyphoidal incision for newborns (and a partial lower or complete median sternotomy for older children). Nine patients had previous cardiac surgery for complex congenital defects. The remaining 12 young children suffered from congenital AV-Block (CAVB). Twenty-one bipolar epicardial electrodes (Medtronic Capsure epi) were fixed to the right ventricle, 15 had additional implantation of a bipolar atrial lead. The pacemaker generator (Medtronic Kappa 701) was implanted into the right upper abdominal wall. Indications for revision were recorded. No mortality was observed; pacing and sensing parameters remained stable up to a 5-year follow-up. A total of four reoperations occurred. Three of the four revisions were caused by ventricular electrode fracture. At revision, two electrodes were broken at the crossing between the pericardial cavity and the abdominal wall, one bipolar lead at the Y-division into the two tip electrodes. One reoperation was due to a pacemaker recall. All revisions were performed without complications.

CONCLUSION

In our institute epicardial pacing in young children was associated with a satisfactory clinical outcome, but also a significant number of failures leading to reoperation, mainly due to electrode fracture caused by the muscular activity of this patient group. Reoperations were performed at a low risk.

Pacemaker selection: time for a rethinking of complex pacing systems?The opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology

Evidence from randomized trials indicates that the clinical benefits of dual-chamber (DDD) pacing are modest: (i) no significant differences exist between physiological pacing and single-chamber pacing in mortality and stroke; (ii) ventricular desynchronization resulting from chronic right-ventricular pacing in DDD mode, induces a significantly increased incidence of atrial fibrillation (AF) and heart failure hospitalizations; (iii) AF pacing prevention and therapy algorithms have shown a modest to minimal or absent efficacy; (iv) the widespread use of physiological pacemakers is not an economically attractive strategy. Thus, these data provide a reliable body of evidence on which to make more rationale clinical decisions for individual patients and policy decisions for health costs saving. The cheaper single-chamber AAI(R) or VVI(R) has been shown to satisfy both conditions in most cases of sinus node disease and AV block.

[Pediatric cardiac pacing: indications, implant techniques, pacing mode]

Over the last years, pacing leads design and pacemaker (PM) generator size, reliability, and longevity have markedly improved, so that reliable paediatric implant can now be performed at any age with a low complication rate. Main indications include congenital and postoperative atrioventricular block (AVB) and postoperative sick sinus syndrome. Implantation of a PM is mandatory for children who are symptomatic from syncope or congestive heart failure and for those who have advanced block persisting more than 10 days after cardiac surgery. Criteria for pacing have been established in relation with the bradycardia and prophylactic pacing is recommended in children with congenital AVB and a mean heart rate <50 beats/minute. The majority of paediatric cardiologists recommend epicardial pacing in children less than 10 kg and when venous access to the heart is limited by congenital anomalies or prior operation; for older children, transvenous implantation has become the technique of choice. As heart rate is the main determinant of cardiac output at exercise in children with normal heart structures, the VVI-R mode is an alternative to dual chamber transvenous pacing in young patients. Patients with isolated sinus failure are paced in the atrium. Although the majority of patients are doing well, late complications within the paediatric population include venous thrombosis and difficulties in lead extraction. Myocardial dysfunction in children with congenital AVB is increasingly reported, but it is not determined whether it is due to the underlying disease or to right ventricular apical pacing and adverse remodelling.