Indications and techniques of pediatric cardiac pacing

T Waves May Not Be What They Seem!

A 39-year-old women who received a transvenous dual-chamber pacemaker in childhood developed 20 years later severe tricuspid valve stenosis induced by the leads and worsened by a pseudo-pacemaker syndrome. (Level of Difficulty: Intermediate.).

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.

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.

Gene Delivery for the Generation of Bioartificial Pacemaker

Electronic pacemakers have been used in patients with heart rhythm disorders for device-supported pacing. While effective, there are such shortcomings as limited battery life, permanent implantation of catheters, the lack of autonomic neurohumoral responses, and risks of lead dislodging. Here we describe protocols for establishing porcine models of sick sinus syndrome and complete heart block, and the generation of bioartificial pacemaker by delivering a strategically engineered form of hyperpolarization-activated cyclic nucleotide-gated pacemaker channel protein via somatic gene transfer to convert atrial or ventricular muscle cardiomyocytes into nodal-like cells that rhythmically fire action potentials.

How pacemakers work and simple programming: a primer for the non-electrophysiologist

Paediatric pacemaker management is challenging because of the small patient size, complex cardiac anatomy, and unique programming considerations. Hardware placement options include epicardial and transvenous systems. When pacemaker malfunction is suspected, a systematic approach is required to determine whether there is malfunction in pacing, sensing, or no output due to hardware problem. In most cases, simple reprogramming may circumvent the problem and allow retention of the pacemaker system.

Systemic venous atrium stimulation in transvenous pacing after mustard procedure

We present the case of a young woman corrected with a Mustard procedure undergoing successful transvenous double chamber pacemaker implantation with the atrial lead placed in the systemic venous channel. The case presented demonstrates that, when the systemic venous atrium is separate from the left atrial appendage, the lead can be easily and safely placed in the systemic venous left atrium gaining satisfactory sensing and pacing thresholds despite consisting partially of pericardial tissue.

Minimally invasive resynchronization pacemaker: a pediatric animal model

PURPOSE

We developed a minimally invasive epicardial pacemaker implantation method for infants and congenital heart disease patients for whom a transvenous approach is contraindicated. The piglet is an ideal model for technical development.

DESCRIPTION

In 5 piglets we introduced a needle through subxiphoid approach under thoracoscopic guidance, inserting a wire into the pericardial space. Pacing leads were affixed to the left ventricular free wall and left atrial appendage. After verifying functionality with atrial and ventricular pacing and sensing, animals were euthanized. Pacemaker monitoring occurred daily for 4 days in the fifth animal.

EVALUATION

Through minimally invasive pericardial access, we directly visualized and fixated pacing leads to the left ventricle and left atrial appendage, successfully pacing atrium and ventricle. Epicardial structures were visualized. One piglet had contralateral pneumothorax, which resolved with needle decompression. No other adverse events occurred.

CONCLUSIONS

Minimally invasive epicardial pacemaker implantation in an infant model is feasible and effective. This innovation may be of value for pacing and resynchronization in infants and congenital heart disease patients. Survival studies with permanent generator implantation are under way.

Gene- and cell-based bio-artificial pacemaker: what basic and translational lessons have we learned?

Normal rhythms originate in the sino-atrial node, a specialized cardiac tissue consisting of only a few thousands of nodal pacemaker cells. Malfunction of pacemaker cells due to diseases or aging leads to rhythm generation disorders (for example, bradycardias and sick-sinus syndrome (SSS)), which often necessitate the implantation of electronic pacemakers. Although effective, electronic devices are associated with such shortcomings as limited battery life, permanent implantation of leads, lead dislodging, the lack of autonomic responses and so on. Here, various gene- and cell-based approaches, with a particular emphasis placed on the use of pluripotent stem cells and the hyperpolarization-activated cyclic nucleotide-gated-encoded pacemaker gene family, that have been pursued in the past decade to reconstruct bio-artificial pacemakers as alternatives will be discussed in relation to the basic biological insights and translational regenerative potential.

Discovery and management of diaphragmatic hernia related to abandoned epicardial pacemaker wires in a pregnant woman with {S,L,L} transposition of the great arteries

Epicardial pacemaker leads placed during childhood are often not removed when transvenous systems are placed later in life. The risk of complications related to retained pacemaker leads and generators is not clear but is generally considered low. We report the case of a 23-year-old pregnant woman who presented with left upper quadrant pain at 20 weeks gestation. The patient was born with {S,L,L} transposition of the great arteries and had high-grade conduction disease in infancy compelling epicardial pacemaker placement. A standard transvenous pacemaker was placed at age 9 years, without removal of the epicardial system. The patient's abdominal pain was attributed to herniation of abdominal contents through a diaphragmatic defect at the site of the abandoned epicardial pacing wire. Her pain improved spontaneously but worsened later in pregnancy leading to repair of the diaphragmatic hernia via anterolateral thoracotomy at 30 weeks gestation. The procedure was well tolerated by mother and fetus. At 38 3/7 weeks gestation, the patient underwent uneventful delivery by cesarean section for breech presentation. This case illustrates the importance of multidisciplinary collaboration in the care of women with congenital heart disease.

Epicardial versus endocardial permanent pacing in adults with congenital heart disease

BACKGROUND

Permanent pacing (PM) in patients with congenital heart disease (CHD) presents unique challenges-with little known about the long-term outcomes.

METHODS

Pacemaker complications and reinterventions were reviewed over a 38-year period and were grouped by epicardial or endocardial approaches.

RESULTS

The average age at intervention was 37 ± 19 years for 106 patients and 259 PM procedures were performed (2.4 ± 2 per patient). From the first PM procedure, patients were followed for 11.6 ± 14 years. The most common indications for initial PM intervention were heart block (25%) and sinus node dysfunction (20%), yet reintervention was driven primarily by lead failure (49%). Endocardial systems were initially implanted in 73 patients (67%). Epicardial pacing was more common in patients with complex CHD (p = 0.006), cyanosis (p < 0.001), residual shunts (0.01), or Ebstein's anomaly (p = 0.01). Fifty-one devices (28%) developed lead or generator complications. Epicardial systems were most likely to develop lead failure (p < 0.0001), predominantly in the ventricular lead (p < 0.0001). Endocardial systems were found to be more durable than the epicardial systems (p = 0.023), and Ebstein's anomaly or an epicardial system was an independent predictor of lead failure.

CONCLUSIONS

Permanent pacing in CHD is associated with considerable morbidity and the need for repeat intervention, especially in those with Ebstein's anomaly. Epicardial pacing systems appear to have a higher incidence of lead failure and are significantly less durable in this group.

Pacemaker Lead Prolapse through the Pulmonary Valve in Children

BACKGROUND

Transvenous pacemaker leads in children are often placed with redundant lead length to allow for anticipated patient growth. This excess lead may rarely prolapse into the pulmonary artery and potentially interfere with valve function. We sought to determine the response to lead repositioning on pulmonary valve insufficiency.

METHODS

Retrospective reviews of demographics, lead type, implant duration, and radiography and echocardiography.

RESULTS

A total of 11 pediatric patients were identified with lead prolapse through the pulmonary valve, of which nine patients underwent procedures to retract and reposition the lead (age at implant 9 +/- 4 years, age at revision 13 +/- 4 years). The implant duration prior to revision was 4 +/- 3 years. Two leads required radiofrequency extraction sheaths for removal, two pulled back using a snare, while five leads were simply retracted and repositioned. Tricuspid regurgitation was none/trivial (three), mild (four), or moderate (two) and only two improved with repositioning or replacement. Pulmonary regurgitation preoperatively was mild (three), mild-moderate (two), or moderate (four) compared with trivial (three), mild (four), and moderate (two) after revision. Patients with longer-term implanted leads had less improvement in pulmonary insufficiency. Two patients had mild pulmonary stenosis from lead-related obstruction.

CONCLUSIONS

Prolapse of transvenous pacing leads into the pulmonary artery can occur when excess slack is left for growth. Leads can often be repositioned, but may require extraction and replacement, particularly if chronically implanted and adherent to valve apparatus. Lead revision does not always resolve pulmonary insufficiency, potentially leaving permanent valve damage.

Long-term follow-up after pacemaker implantation in neonates and infants

BACKGROUND

Pacemaker (PM) system implantation in neonates and infants is often complicated by hemodynamic instability, small vessel size, and abnormal cardiovascular anatomy. Thus, an open surgical approach for epicardial lead insertion is often required. We assessed the long-term outcomes after epicardial PM implantation in this age group.

METHODS

Between 1992 and 2004, 22 consecutive patients underwent PM implantation within the first year of life. Bipolar steroid-eluting epicardial leads (Medtronic CapSure Epi 10366 and 4968) were inserted through median sternotomy, the sybxyphoid approach, or thoracotomy, and connected to various pulse generators.

RESULTS

Pacemakers were implanted at a median age of 35 days (range, 1 to 300). Intracardiac anatomy was abnormal in 17 patients. Indications for PM therapy were heart block in 18 patients and sinus node dysfunction in 4 patients. During a median follow-up of 4.6 years (range, 4 days to 12.8 years), 7 devices were replaced owing to end of battery life (n = 6) or elective device repositioning (n = 1), at a median of 4.1 years (range, 1 to 7.8). One dislodged ventricular lead and 2 atrial lead sensing failures were observed. Sensing, pacing thresholds, and lead impedances showed good implant and stable follow-up values.

CONCLUSIONS

Pacemaker-associated morbidity is low. Pacemaker system complications with epicardial leads are rare. Battery life is relatively shorter compared with children and adults because of the fast heart rate and complete PM dependency in most of these children. Even for neonates and infants, modern pacemaker therapy is feasible, safe, and effective.

Transvenous pacing after the Mustard procedure: considering the complications

Disturbances of rhythm and conduction in patients undergoing surgery for transposition of the great arteries have been widely reported. Some of these patients require implantation of a permanent pacemaker, especially those in whom symptomatic sick sinus syndrome is diagnosed. We present the case of a 29-year-old male corrected with a Mustard procedure, who received a pacemaker for progressive atrioventricular conduction disturbances and sinus node dysfunction, and we review the possible complications associated with transvenous pacemaker implantation in these patients. (Neth Heart J 2007;15:387-89.).

Cardiac conduction through engineered tissue

In children, interruption of cardiac atrioventricular (AV) electrical conduction can result from congenital defects, surgical interventions, and maternal autoimmune diseases during pregnancy. Complete AV conduction block is typically treated by implanting an electronic pacemaker device, although long-term pacing therapy in pediatric patients has significant complications. As a first step toward developing a substitute treatment, we implanted engineered tissue constructs in rat hearts to create an alternative AV conduction pathway. We found that skeletal muscle-derived cells in the constructs exhibited sustained electrical coupling through persistent expression and function of gap junction proteins. Using fluorescence in situ hybridization and polymerase chain reaction analyses, myogenic cells in the constructs were shown to survive in the AV groove of implanted hearts for the duration of the animal's natural life. Perfusion of hearts with fluorescently labeled lec-tin demonstrated that implanted tissues became vascularized and immunostaining verified the presence of proteins important in electromechanical integration of myogenic cells with surrounding re-cipient rat cardiomyocytes. Finally, using optical mapping and electrophysiological analyses, we provide evidence of permanent AV conduction through the implant in one-third of recipient animals. Our experiments provide a proof-of-principle that engineered tissue constructs can function as an electrical conduit and, ultimately, may offer a substitute treatment to conventional pacing therapy.