compatibility must be determined Other features to evaluate are the different programmable options, including automatic capture, atrial therapies, size, and battery capacity Various lead characteristics include diameter, polarity, insulation material, and fixation mechanism The family's ability to send remote monitoring for surveillance purposes is important to assess Epicardial Versus Endocardial Implantation Pacing leads are recognized as the most vulnerable and problematic components of the pacemaker system Factors such as the patient's growth, unique anatomy, scar, need for lifelong pacing, activity level of the child, and the long-term vascular access issues increase the susceptibility to lead damage Earlier epicardial leads with the screw-in mechanism resulted in acute inflammation and subsequent scarring at the myocardial interface Newer steroid-eluting leads have a response comparable to that of endocardial leads Epicardial systems in the acute period have a higher incidence of developing pericardial effusion or postpericardiotomy syndrome The risk of subclavian or innominate vein thrombosis commonly parallels the vessel size at initial implant Studies have sought to define risk factors for venous obstruction.196 Initially, calculations relating hardware to body surface area were used More recent studies have not correlated age at implant, body surface area, prior heart surgeries, lead duration, number of procedures, or lead index to be statistically significant.197 Preserving long-term vessel patency for the possible need to add an additional lead or lead extraction in the future can be difficult in an already challenging population Unipolar Versus Bipolar Leads Unipolar and bipolar pacing systems have been used since the first decade of cardiac pacing Both permit electricity to flow from one pole to the other and deliver an electrical charge A unipolar lead is a single-conductor lead with an electrode located at the tip Therefore the electrical circuit is dependent on the single electrode lead to the generator and myocardium The benefits of unipolar systems are that the leads are smaller in diameter and have more flexibility Disadvantages are lower impedance, a shorter battery life, an increase in oversensing extracardiac signals, skeletal muscle pacing, and not as much flexibility if any insulation damage to the lead arises A bipolar lead has two separate isolated conductors within a single lead; the distal electrode is at that tip and the proximal electrode about 2 cm proximal to the tip It is important to remember that bipolar systems do not always demonstrate pacing spikes on a surface ECG and can make interpreting an ECG more challenging In a bipolar system, if there is discrete lead damage, there is the option of reprogramming the device to a unipolar system and possibly maintaining adequate sensing and thresholds Congenital Heart Disease Patients with complex congenital heart disease will likely have multiple openheart operations over the course of their lives As a result, patients have myocardial scarring that creates challenges for optimum lead placement and performance Surgical palliations in the congenital heart disease population produce unique interventions and lead placement approaches, as seen in the single-ventricle and atrial-switch population Epicardial devices are routinely used in small children as well as patients with intracardiac shunts, prosthetic tricuspid valves, or chambers that cannot be readily accessed from the vasculature As a result, epicardial leads are often required The decision as to which lead or leads and which chamber should be thoughtfully discussed with the cardiac surgeon prior to proceeding to the operating theater An understanding of the anatomy prior, surgical approaches, and echocardiographic areas of dyssynchrony should be collectively discussed so as to optimize lead durability and lead integrity and to optimize hemodynamics for particular patients Studies have been performed to identify the life span of epicardial systems given these concerns and found the lead survival to be acceptable.198 Patients with transvenous systems and the presence of an intracardiac shunt are at a greater than twofold increased risk of pulmonary emboli or systemic embolic events.199 The approach to the patient with univentricular palliation varies between centers and operators, with most utilizing epicardial systems in this population Pacemaker Infection In healthy patients with implanted devices, the recent guidelines from the American Heart Association for the prevention of bacterial endocarditis do not recommend antibiotic prophylaxis Risk factors for the development of deeppocket infections include reoperation and trisomy 21.200 Superficial infections should be followed closely to identify if there is progression to a deep-pocket infection Once such an infection has occurred, the entire hardware system must be removed Signs and symptoms of infection can be skin breakdown at the incision site, an elevated white cell count, fever, malaise, localized edema, increasing erythema, an increase in warmth at the incision, discharge, wound dehiscence, and/or pain The most common organisms identified in device infections are gram-positive bacteria found in staphylococcal infections Gramnegative bacteria accounts for fewer than 18% of infections, and about 15% of device infections are culture-negative If a patient is pacemaker-dependent, often a temporary lead can be placed at a remote site while the appropriate antibiotics are given and the device and leads are removed If the leads are chronic and likely not easily removable, consideration for a more invasive lead extraction should be entertained Transvenous lead extractions are high-risk procedures and should be performed at a center with readily available surgical expertise Recent guidelines have been published regarding lead extraction in children and adults.200 Dual Versus Single-Chamber Devices Major trials have been performed in adult populations to identify the value of single- versus dual-chamber devices The rationale for dual-chamber systems is to preserve AV synchrony and subsequently preserve myocardial function The benefits of dual-chamber pacing to promote AV synchrony have been well defined; however, there is evidence to support minimizing ventricular pacing Programming a fixed long AV delay may minimize ventricular pacing but is sometimes not feasible In the pediatric and congenital heart disease population decisions are often driven by patient size and anatomy The younger patients will often be given an initial single-chamber system that is later upgraded to a dualchamber system at device revision A biventricular pacing system may be recommended in patients with impaired LV function who require permanent pacing Leadless Pacing Lead failure is a common complication of pacemaker placement in the pediatric population and is often due to insulation breaks, lead fracture, dislodgement, an increased risk for infection, and vascular occlusion These consequences can ... Programming a fixed long AV delay may minimize ventricular pacing but is sometimes not feasible In the pediatric and congenital heart disease population decisions are often driven by patient size and anatomy... recommended in patients with impaired LV function who require permanent pacing Leadless Pacing Lead failure is a common complication of pacemaker placement in the pediatric population and is often due to insulation breaks, lead fracture, dislodgement, an increased risk for infection, and vascular occlusion