DDD pacemaker implantation after Fontan-type operations

Novel approaches for leadless pacemaker implantation in the extra-cardiac Fontan cohort: Options to avoid leaded systems or epicardial pacing

BACKGROUND

Fontan surgery, a palliative procedure for single ventricle patients, often leads to the need for permanent pacing. Epicardial pacing has limitations, while transvenous pacing carries risks in the Fontan circulation. This case series introduces a novel approach of leadless pacemaker implantation in the extra-cardiac Fontan (ECF) cohort to overcome these limitations.

METHODS

The study includes four cases of leadless pacemaker (Micra™) implantation in patients with ECF. Procedures were performed under general anesthesia with guidance from trans-esophageal echocardiography. Various access routes were used, including trans-carotid and trans-fenestration approaches. Procedural details, parameters, and follow-up data were collected.

RESULTS

All leadless pacemaker implantations were successful, with satisfactory electrical parameters and stable pacing postprocedural outcomes during short-term follow-up. One patient required closure of their fenestration for symptomatic desaturation post procedurally.

CONCLUSIONS

Leadless pacemaker implantation via trans-carotid and trans-fenestration approaches appears to be a feasible back up option for pacing in Fontan patients where other options have been exhausted or there is a patient choice to avoid surgery. These techniques provide an option to avoid leaded systems or epicardial pacing, reducing the need for multiple thoracotomies and addressing challenges associated with surgical pacing leads. Further studies are needed to evaluate long-term outcomes and assess the broader application of leadless pacemakers in the Fontan population.

Epicardial atrial pacing after the extracardiac Fontan operation: Feasibility of an entirely transvenous approach

This series describes an innovative technique for pacing in patients with sinus node dysfunction after extracardiac Fontan surgery. This transpulmonary approach to the left atrial epi-myocardium has been successfully applied to three patients at two centers and resulted in excellent acute and midterm pacing characteristics without known complications. The principal advantage of this procedure in comparison to prior iterations is the absence of pacing material within the pulmonary venous atrium, so that future systemic thromboembolism risk is minimized. The transpulmonary approach for permanent atrial pacing offers a novel solution to the unique challenges for patients after extracardiac Fontan operation.

Effect of Ventricular Pacing on Morbidity in Adults After Fontan Repair

Implantation of a permanent pacemaker is a negative prognostic marker in patients with Fontan palliation; however, data delineating outcomes in adult patients with pacemaker requirements are lacking. We hypothesize that high ventricular pacing burden is associated with adverse outcomes in adult Fontan patients. We performed a retrospective review comprising adult patients with history of Fontan repair. A high burden of ventricular pacing was defined as ≥40% pacing. Major adverse clinical events (MACE) were defined as all-cause mortality or need for advanced cardiac therapies (ventricular assist device or heart transplant). A total of 145 adult patients with Fontan were studied for a median of 3.1 years. Twenty (14%) patients had implanted pacemakers with ≥40% ventricular pacing. Twelve events occurred in those with ≥40% ventricular pacing (incidence 60.0%) versus 11 in those without (incidence 8.8%). In multivariable analysis, ≥40% ventricular-pacing (odds ratio 12.51, confidence interval [CI] 3.56 to 43.83, p <0.001) was associated with MACE independent of initial Fontan type, New York Heart Association functional class at baseline, or history of atrial tachyarrythmia. In survival analysis, patients with ≥40% ventricular pacing had nearly 8 times the risk of MACE compared with those with a lower ventricular pacing burden (hazard ratio 7.79, 95% CI 2.56 to 23.66, p <0.001), whereas patients with atrial-only or <40% ventricular pacing burden had a trend toward higher hazard of MACE compared with those without permanent pacemaker (hazard ratio 3.38, 95% CI 0.92 to 12.47, p = 0.07) that did not meet statistical significance. These findings suggest that high ventricular pacing burden contributes to poor outcomes in the adult Fontan patients and bear consideration when determining optimal treatment of tachyarrhythmias in this population.

Voltage mapping to guide pacemaker placement in patients with CHD

Transvenous pacemaker implantation for sinus node dysfunction in patients with Fontan palliation presents the difficulty of finding suitable pacing tissue and the potential of causing vascular obstruction in a low-flow circuit. We describe a patient who underwent electro-anatomic voltage mapping to guide a transvenous single chamber lead within her Fontan baffle. This highlights the use of advanced mapping technologies for pacemaker implantation in complex cyanotic heart disease.

Endocardial transvenous pacing in patients with surgically palliated univentricular hearts: A review on different techniques, problems and management

Fontan surgery and its modifications have improved survival in various forms of univentricular hearts. A regular atrial rhythm with atrioventricular synchrony is one of the most important prerequisite for the long-term effective functioning of this preload dependent circulation. A significant proportion of these survivors need various forms of pacing for bradyarrhythmias, often due to sinus nodal dysfunction and sometimes due to atrioventricular nodal block. The diversion of the venous flows away from the cardiac chambers following this surgery takes away the simpler endocardial pacing options through the superior vena cava. The added risks of thromboembolism associated with endocardial leads in systemic ventricles have made epicardial pacing as the procedure of choice. However challenges in epicardial pacing include surgical adhesions, increased pacing thresholds leading to early battery depletion and frequent lead fractures. When epicardial pacing fails, endocardial lead placement is equally challenging due to lack of access to the cardiac chambers in Fontan circulation. This review discusses the univentricular heart morphologies that may warrant pacing, issues about epicardial pacing, different techniques for endocardial pacing in patients with disconnected superior vena cava, pacing in different modifications of Fontan surgeries, issues of systemic thromboembolism with endocardial leads, atrioventricular valve regurgitation attributed to pacing leads and device infections. In a vast majority of patients following Glenn shunt and Senning surgery, an epicardial pacing and lead replacement is always feasible though technically very difficult. This article highlights the different options of transatrial and transventricular endocardial pacing.

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Fontan surgery prolongs the mean survival of patients with univentricular hearts beyond 30 years.

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9-20% of survivors need permanent pacing for bradyarrhythmias.

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Epicardial pacing is preferred as the first choice for permanent pacemaker.

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There is 20-40% failure of permanent pacing at 10 years due to high threshold, lead fractures.

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Repeated epicardial pacing with surgical revisions are difficult.

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Endocardial pacing involves special techniques.

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Manoeuvring through fenestrations,venous collaterals, hepatic veins, pulmonary valve or hybrid peratrial routes is needed.

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Systemic thromboembolism, endocarditis and systemic AV valve regurgitation should be prevented by meticulously measures.

Transvenous Versus Epicardial Pacing in Fontan Patients

Up to 10% of Fontan patients require pacemakers; an epicardial approach has historically been used. A transvenous approach can be used but carries risk of Fontan obstruction, thromboembolism, and can be technically challenging. The safety and efficacy of these approaches is not well described. The aim of this study was to compare epicardial and transvenous pacemaker outcomes in Fontan patients, specifically, device performance and adverse event rate. A retrospective review was performed on Fontan pacemaker patients followed at a single institution. Thirty-one Fontan pacemaker patients were identified between 1985 and 2017. Twenty-six had an epicardial system, five transvenous, and three converted from epicardial to transvenous. Average atrial lead sensing at placement was 3.23 versus 2.35 mV (p = 0.52) for epicardial and transvenous leads, respectively. Median atrial and ventricular lead longevity was 86.4 versus 98.8 months (p = 0.56) and 73.2 versus 140 months (p = 0.3) with generator longevity of 65.5 versus 73.9 (p = 0.16) months for epicardial versus transvenous systems, respectively. One major complication occurred in a transvenous patient, and two minor complications occurred in epicardial patients. All transvenous patients received warfarin except one, who converted to dabigatran. Epicardial patients received aspirin (n = 20), warfarin (n = 3) or a warfarin/aspirin combination (n = 3). No thromboembolic events occurred. System revision was required in 13 epicardial and 5 transvenous patients. There were two deaths, none related to the pacemaker system. Transvenous pacemakers can be utilized with equal efficacy compared to epicardial pacemakers with trends toward longer lead longevity in transvenous pacemaker systems.

Approaching the 50th anniversary of the first Fontan procedure. What is the current state of treatment provided to patients with functional single ventricles?

Nearly 50 years after the pioneering procedure performed by Francis Fontan and Eugene Baudet, which has saved the lives of thousands of children, there are still more questions than answers regarding therapeutic management. The complex pathophysiology of Fontan circulation, the lack of clear guidelines, and the shift in the care of such patients from pediatric cardiological and cardiac surgical centers to ones dealing with adult patients, cause new threats. This paper outlines the fundamental issues related to the pathophysiology of Fontan circulation and reviews the literature on the methods of treating complications characteristic of this group of patients.

Utility of preoperative Holter monitoring in children undergoing extracardiac conduit Fontan operation

BACKGROUND

In patients undergoing extracardiac conduit Fontan (ECF) who require postoperative pacing, epicardial leads are usually required because of anatomical constraints. If indicated, these could be conveniently placed at the time of ECF. We have routinely performed ambulatory 24-hour Holter monitoring before ECF to determine the presence or absence of preoperative sinus node dysfunction, in an attempt to avoid repeat sternotomy at a later time.

METHODS

We performed a retrospective study of all patients undergoing ECF from January 2000 to December 2015.

RESULTS

Two hundred sixteen patients met inclusion criteria. Patients were separated into two groups, those with preoperative Holter monitoring (PHM, n = 150) and those without (No-PHM, n = 66). Ten patients (4.6%) underwent permanent pacemaker implantation at the time of ECF (eight patients [5.3%] in PHM vs two patients [3.0%] in No-PHM, P = 0.46). There were seven (3.2%) patients who underwent pacemaker implantation after ECF requiring repeat sternotomy (four patients [2.7%] in PHM vs three patients [4.5%] in No-PHM, P = 0.47). Fourteen (6.5%) patients underwent permanent epicardial lead placement without a pulse generator at the time of ECF. None from this group underwent pacemaker implantation to date (median follow-up of 5.7 years). The overall incidence of pacemaker implantation was 9.3% (20 patients).

CONCLUSIONS

In our series, arrhythmia disturbances requiring pacing after ECF occurred in just over 9% of patients. While PHM in those patients may help predict which patients might require postoperative pacing, this approach did not result in a significant decrease in those patients requiring repeat sternotomy for pacemaker implantation.

Transhepatic permanent pacing in a child with complex cyanotic heart disease after total cavo pulmonary shunt (Kawashima repair)

Complex cyanotic congenital heart diseases with left isomerism are sometimes associated with atrioventricular nodal conduction disturbances that may need permanent pacing. Surgical palliation in such anatomy connecting the superior vena cava to the pulmonary artery precludes a transvenous access for an endocardial pacing lead to the ventricles. Epicardial leads in these patients fail if the pacing thresholds are very high. We report transhepatic permanent ventricular lead implantation for a young boy with heterotaxy complicated by complete heart block.

Cardiac pacing in paediatric patients with congenital heart defects: transvenous or epicardial?

AIMS

Cardiac pacing is a difficult technique in children, particularly in patients with congenital heart defects (CHDs). Few studies to date have addressed this topic.

METHODS AND RESULTS

We performed a retrospective analysis of the results of a single centre. Between 1982 and 2008, 287 patients with CHD, median age of 5 years (25-75%, 1-11) underwent cardiac pacing for sinus node dysfunction (SND) and atrioventricular block (AVB); 97% of patients underwent at least one heart surgery. Endocardial systems (Endo) were implanted in 117 patients, epicardial systems (Epi) in 170, with 595 leads (228 Endo, 367 Epi). Endocardial systems showed a significantly older age group with more frequent SND; Epi a younger age group, with more frequent AVB, greater number of surgical interventions. Perioperative complications were mortality 0.6% (Epi), pericardial effusion 0.6% (Epi), and haemothorax 3.4% (Endo). The median follow-up is 5 (2-10) years: the pacing system failed in 29% of patients, 13% Endo, and 40% Epi (P < 0.0001). Multivariate analysis showed a significantly higher risk of failure for Epi, a lower implant age, greater the number of leads implanted. The risk of malfunction of the leads increases significantly for Epi and the younger age when implanted. The steroid-eluting leads have a lower risk of malfunction (P = 0.05), steroid-eluting Endo leads provide significantly better outcomes than Epi.

CONCLUSION

Cardiac pacing in paediatric patients with CHD shows satisfactory results in the long term. Endocardial systems show significantly better results than Epi systems. A younger age when implanted is a risk factor for complications at follow-up.

Comparison of Fontan survivors with and without pacemakers: a report from the Pediatric Heart Network Fontan Cross-Sectional Study

OBJECTIVE

Although many Fontan patients undergo pacemaker placement, there are few studies characterizing this population. Our purpose was to compare clinical characteristics, functional status and measures of ventricular performance in Fontan patients with and without a pacemaker.

PATIENTS AND DESIGN

The National Heart, Lung, and Blood Institute funded Pediatric Heart Network Fontan Cross-Sectional Study characterized 546 Fontan survivors. Clinical characteristics, medical history and study outcomes (Child Health Questionnaire [CHQ]), echocardiographic evaluation of ventricular function, and exercise testing) were compared between subjects with and without pacemakers.

RESULTS

Of 71 subjects with pacemakers (13%), 43/71 (61%) were in a paced rhythm at the time of study enrollment (age 11.9 ± 3.4 years). Pacemaker subjects were older at study enrollment, more likely to have single left ventricles, and taking more medications. There were no differences in age at Fontan or Fontan type between the pacemaker and no pacemaker groups. There were no differences in exercise performance between groups. CHQ physical summary scores were lower in the pacemaker subjects (39.7 ± 14.3 vs. 46.1 ± 11.2, P =.001). Ventricular ejection fraction z-score was also lower (-1.4 ± 1.9 vs. -0.8 ± 2.0, P =.05) in pacemaker subjects.

CONCLUSIONS

In our cohort of Fontan survivors, those with a pacemaker have poorer functional status and evidence of decreased ventricular systolic function compared to Fontan survivors without a pacemaker.

Successful one-lung ventilation in a patient with the Fontan circulation undergoing thoracotomy: a case report

The incidence of noncardiac surgery in patients with the Fontan circulation has increased over the years due to the elongated life expectancy of these patients. In patients with the Fontan circulation, pulmonary blood flow is passive, so it is important to keep pulmonary vascular resistance low. One-lung ventilation (OLV) can have adverse effects on the Fontan circulation due to hypoxia, hypoxic pulmonary vasoconstriction, hypercarbia, and increased airway pressure. We present a case of successful OLV in a patient with the Fontan circulation and describe our perioperative management.

Oral budesonide as a therapy for protein-losing enteropathy in patients having undergone Fontan palliation

BACKGROUND

  Protein-losing enteropathy is associated with Fontan palliation for single-ventricle physiology and has been difficult to treat. Limited data suggest the successful use of oral budesonide (Entocort, AstraZeneca) as a palliative measure.

METHODS

  We examine our single-institution retrospective experience in eight patients who were treated with this therapy.

RESULTS

  Median pretherapy albumin level was 1.7 g/dL (range 1.0-2.7 g/dL), 3 months after therapy was 3.1 g/dL (range 2-4.8 g/dL), and by the end of the first year was 3.4 g/dL (range 2.1-5.3 g/dL). All patients had at least a transient improvement, and at latest follow-up (median 29 months, range 3-51 months) five patients remain on therapy. Five of eight patients had required pretherapy albumin transfusions; one patient required albumin infusions after therapy. Four patients had side effects associated with the medication.

CONCLUSIONS

  Oral budesonide is an additional therapy that has the potential to improve symptoms and delay need for heart transplantation in this patient population.

Protein-losing enteropathy: integrating a new disease paradigm into recommendations for prevention and treatment

Protein-losing enteropathy is a relatively uncommon complication of Fontan procedures for palliation of complex congenital cardiac disease. However, the relative infrequency of protein-losing enteropathy belies the tremendous medical, psychosocial and financial burdens it places upon afflicted patients, their families and the healthcare system that supports them. Unfortunately, because of the complexity and rarity of this disease process, the pathogenesis and pathophysiology of protein-losing enteropathy remain poorly understood, and attempts at treatment seldom yield long-term success. The most comprehensive analyses of protein-losing enteropathy in this patient population are now over a decade old, and re-evaluation of the prevalence and progress in treatment of this disease is needed. This report describes a single institution experience with the evaluation, management, and treatment of protein-losing enteropathy in patients with congenital cardiac disease in the current era, follows with a comprehensive review of protein-losing enteropathy, focused upon what is known and not known about the pathophysiology of protein-losing enteropathy in this patient population, and concludes with suggestions for prevention and treatment.

Permanent atrial pacing lead implant route after Fontan operation

BACKGROUND

Atrial pacing is indicated for sinus node dysfunction (SND) after Fontan surgery; preferred lead implantation technique is debated. We compare outcomes of transvenous (TV) and epicardial (Epi) atrial lead implants in this population.

METHODS

Retrospective review of Fontan patients undergoing atrial lead implant between 1992 and 2007. Demographics, lead performance data, and outcomes were analyzed.

RESULTS

78 patients had 90 leads implanted: 25 via TV route and 65 via Epi route. Median follow-up was 1.6 years (TV) and 3.6 years (Epi). TV leads were implanted in older patients (23.1 vs 9.3 years, P < 0.001) and at longer intervals after Fontan (15.2 vs 4.9 years, P < 0.001). Pacing indication for most TV leads was SND, while Epi leads were also indicated for atrioventricular block. Acute complication rates were similar (8% TV vs 19% Epi, P = 0.23), but median hospital stay was shorter for TV (2 vs 5 days, P = 0.03). Thrombus was observed in five patients (two in TV; three in Epi), but no thromboembolic events were observed. Mean lead survival was similar (TV 9.9 vs Epi 7.8 years, P = NS). Energy threshold was lower at implant for TV leads (0.9 vs 2.2 microJ, P = 0.049), but similar at follow-up (1.2 vs 2.6 microJ, P = 0.35). Atrial sensing was unchanged over time for TV (2.2 to 2.1 mV, P = NS), but decreased for Epi (3.3 to 2.5 mV, P = 0.02).

CONCLUSIONS

Compared to epicardial leads, transvenous atrial pacing leads may be placed in Fontan patients with lower procedural morbidity and equivalent expectation of lead performance and longevity.

Acute Hemodynamic Effects of Pacing in Patients With Fontan Physiology

OBJECTIVES

The purpose of this research was to assess the hemodynamic response to atrial, ventricular, and dual-chamber pacing in patients with Fontan physiology.

BACKGROUND

Bradycardia, due to sinus node dysfunction or atrioventricular (AV) block, with need for pacing, is common after the Fontan operation. The optimal pacing mode for Fontan patients is unknown, but is critical, as hemodynamic aberrancies may cause severe clinical deterioration. We hypothesized that AV synchrony is vital for maximizing Fontan hemodynamics.

METHODS

A cross-over trial was conducted with 21 patients (age 2 to 18 years, median 4 years; male patients = 13) in the intensive care unit after a Fontan operation. Hemodynamic parameters, including mean left atrial pressure (LAP, in mm Hg), mean pulmonary artery pressure (PAP, in mm Hg), mean arterial blood pressure (MAP, in mm Hg), and indexed cardiac output via Fick (Qs, in l/min/m2) were measured with atrial, ventricular, and dual-chamber pacing. Measurements were made after pacing for 10 min in each mode, and a 10-min rest was given between each pacing maneuver.

RESULTS

Asynchronous ventricular (VOO) pacing resulted in significantly worse hemodynamics when compared to dual-chamber (DOO) and atrial (AOO) pacing with a higher LAP (9.4 VOO; 6.8 DOO; 5.4 AOO) and PAP (15.2 VOO; 13.5 DOO; 12.7 AOO) and lower Qs (3.0 VOO; 3.5 DOO; 3.9 AOO) and MAP (60.1 VOO; 66.5 DOO; 67.2 AOO).

CONCLUSIONS

Asynchronous ventricular pacing, after the Fontan procedure, has acute, adverse hemodynamic consequences (elevated LAP and PAP and decreased Qs and MAP).

Dual Chamber Epicardial Pacing for the Failing Atriopulmonary Fontan Patient

BACKGROUND

The atriopulmonary Fontan circulation leads to arrhythmias, heart failure, or protein-losing enteropathy, eventually requiring conversion. In hesitant patients, we evaluated the effect of dual chamber pacing as a time-buying measure.

METHODS

Between 1997 and 2004, 9 patients (aged, 6 to 18 years) with an atriopulmonary Fontan connection and sinus node dysfunction received dual chamber epicardial pacemaker systems. Indications included refractory arrhythmias (n = 5), protein-losing enteropathy (n = 2), heart failure with effusions (n = 1), and exercise intolerance (n = 2). Data were compared between hospital discharge after pacemaker implantation and last follow-up.

RESULTS

There was no mortality or morbidity. At a follow-up of 3.3 +/- 1.0 years, lead survival was 100%. Both atrial (impedance = 683 +/- 40 Ohm; threshold = 0.8 +/- 0.1 V at 0.5 ms; sensing P waves = 3.3 +/- 0.8 mV) and ventricular (impedance = 630 +/- 68 Ohm; threshold = 1.3 +/- 0.3 V at 0.5 ms; sensing R waves = 8.7 +/- 2.5 mV) leads retained satisfactory pacing characteristics at last control, better than those at discharge. Arrhythmias subsided in all instances and no longer required medication in 3 patients. Protein-losing enteropathy improved temporarily in 1 patient and disappeared in another. Exercise intolerance diminished, and heart failure was controlled.

CONCLUSIONS

Although most atriopulmonary Fontan circulations will need conversion with arrhythmia surgery, patients may delay out of fear. Dual chamber pacing improves single ventricle hemodynamics and can help decompensated Fontan patients. In a multiple-redo setting, a left lateral thoracotomy provides safe access and allows for quantitatively reliable and durable epicardial pacing.

Beat‐to‐Beat Heart Rate Adaptation in Pediatric and Late Adolescent Patients with Closed Loop Rate‐Responsive Pacemakers

The aim of this study was to evaluate the efficacy of physiological rate-responsive pacemakers (Closed Loop Stimulation--CLS) to pace pediatric and late adolescent patients undergoing rest, mental, standing, and exercise testing. Dual-chamber pacemaker is increasingly indicated for young patients. A new physiological pacing mode based on the indirect measure of ventricular contractility (CLS), has shown interesting results in adults, while no data on pediatric patients are available. RR intervals and beat-to-beat systolic and diastolic pressures were monitored in 12 pediatric patients (6 males, mean age 17 years [12-22 years]) who had a transvenous implant of Inos2+-CLS dual-chamber pacemaker (Biotronik GmbH, Berlin, Germany) and endocardial leads. All the patients showed correct electrical parameters at the implant and during the follow-ups. Paced RR intervals decreased significantly (F = 7.28, P = 0.01) from 0.85 +/- 0.08 seconds (rest) to 0.73 +/- 0.10 seconds (mental) and to 0.75 +/- 0.010 seconds (standing); systolic/diastolic pressure was significantly higher (F = 12.2, P = 0.002/F = 13.6, P = 0.001) in mental (134.4 +/- 19.9/74.4 +/- 8.1 mmHg) with respect to rest (115.1 +/- 18.3/61.0 +/- 6.1 mmHg), and standing (118.7 +/- 23.9/67.3 +/- 0.1 mmHg). During exercise the paced RR interval showed significant decrease of about 35% from baseline to maximum load (F = 24.90, P = 0.001) and systolic pressure increased significantly (F = 4.91, P = 0.019) by about 34% from baseline to maximum load. The comparison between paced and spontaneous rates showed very similar values and trend. In addition, CLS mode does not seem to overrun the spontaneous heart activity, when present. This is a study to evaluate CLS pacing in pediatric and late adolescent patients. The study shows that CLS pacing responds to both physical and non-physical stressors, providing physiological pacing rates, as previously observed in adults.

Endocardial Pacing After Fontan-Type Procedures

BACKGROUND

Sinus node dysfunction is a frequent complication of Fontan-type procedure. Epicardial pacing is considered as the standard treatment for these patients.

METHODS AND RESULTS

We evaluated an endocardial approach in seven patients using a 4.1 French bipolar lumenless lead (SelectSecure) that is positioned through a steerable guiding catheter. Either a purely transvenous or an open transatrial approach can be used for lead placement. The smallest child weighed 12 kg. Individual anatomy was assessed preimplantation using magnetic resonance imaging and injection of radiographic contrast agent through the guiding catheter. A pullback pressure recording was used to confirm unimpaired blood flow into the pulmonary artery. Five of our seven patients underwent de novo transvenous atrial lead implantation for AAIR pacing. In the remaining two patients, both atrial and ventricular leads were inserted. One patient with an intraatrial tunnel underwent transvenous-lead placement. The remaining patient with an extracardiac conduit received atrial and ventricular leads implanted through a guiding catheter inserted through an atriotomy. The postoperative management included short- or long-term oral anticoagulation.

CONCLUSIONS

Transvenous endocardial lead implantation avoids the problem of increasing capture thresholds typically observed with epicardial leads. Due to its high tensile strength and lumenless design, the isodiametric lead is expected to remain extractable for an extended period of time.

Congenital heart disease never goes away, even when it has been 'treated': the adult with congenital heart disease

PURPOSE OF REVIEW

As the specialties of pediatrics and pediatric cardiology continue to forge ahead with better diagnoses, medical care, and surgical results, an expanding population of patients with congenital heart disease (CHD) outgrows the pediatric age group, yet does not quite graduate to routine adult cardiology or general medicine. The adult with congenital heart disease (ACHD) faces medical, surgical, and psychosocial issues that are unique to this population and must be addressed as such. This review attempts to discuss and highlight some of the important advances and controversies brought up in the past year, in the care and management of these patients.

RECENT FINDINGS

The past five to 10 years have seen dynamic interest in understanding sequelae of corrected, uncorrected, or palliated congenital heart disease. The search for the ideal surgery, optimal prosthesis, and a smooth transition to adult care continues and is reflected in the vast amount of academic work and publications in this field. Of particular interest, conduit reoperations and single ventricle pathway modifications are still an art and a science in evolution.

SUMMARY

While all are agreed that there is a pressing need to focus on the delivery of care to the adult with congenital heart disease, this essentially requires a clearer understanding of late sequelae of CHD. The sheer heterogeneity of anatomy, age, surgery, and institutional management protocols can make it difficult to develop clear guidelines. This review attempts to give an up-to-date perspective on some of the new findings related to the more common lesions and problems faced in this group.

Endocardial Atrial Pacing Lead Implantation and Midterm Follow-Up in Young Patients with Sinus Node Dysfunction After the Fontan Procedure

The purpose of the study was to investigate the results of endocardial lead implantation, lead performance, and follow-up in young patients after the Fontan procedure. A retrospective study was conducted with patients who had endocardial atrial pacing for SND and intact AVN function after Fontan from two pediatric centers. Patient demographics, pacing, and sensing data of endocardial atrial leads were analyzed at the time of pacemaker implantation and follow-up visits. Fifteen patients (weight 42.6 +/- 35 kg) had transvenous endocardial atrial lead implantation at an average age of 11.4 +/- 6.5 years. Active-fixation leads were used in all patients and steroid elution was present in 12 (80%) patients. Adequate P wave sensing was obtained in patients with sinus rhythm (n = 10); the remaining four patients had junctional rhythm without measurable P waves. Lead failure was not observed in any patient during the follow-up period of 2.9 +/- 2.1 years. The energy threshold at implantation was 1.46 +/- 1.5 microJ, 1.54 +/- 0.75 microJ at 3 months, 0.62 +/- 0.45 microJ at 1 year, 0.72 +/- 0.65 microJ at 2 years, 0.75 +/- 0.55 microJ at 3 years, and 0.8 +/- 0.85 microJ at 5 years postimplant. The lead impedance was 648 +/- 298 omega at implantation, 714 +/- 163 omega at 3 months, 744 +/- 195 omega at 1 year, 734 +/- 198 omega at 2 years, 800 +/- 142 omega at 3 years and 830 +/- 200 omega 5 years postimplant. Anticoagulation therapy (aspirin n = 5, warfarin n = 8) was continued by 13 patients. Complications consisted of a pneumothorax at implantation and a transient ischemic attack in one patient 4 years after pacemaker implant. Endocardial atrial leads offer low energy thresholds and can be implanted relatively safely in Fontan patients.

Recent advances in pacemaker and implantable defibrillator therapy for young patients

PURPOSE OF REVIEW

This review is intended to highlight major clinical advances over the past year related to (1). biventricular pacing as a treatment for dilated myopathy, (2). growing clinical experience with implantable cardioverter defibrillators in pediatrics, (3). technical advances in standard antibradycardia pacing, and (4). an appraisal of the newly updated ACC/AHA/NASPE guidelines for device implant in children and adolescents.

RECENT FINDINGS

Complex rhythm devices are being used more frequently in children. Biventricular pacing to improve ventricular contractility is a rapidly evolving technology that has now been applied to children and young adults with intraventricular conduction delay, such as bundle branch block after cardiac surgery. Implantable defibrillators are also being used for an expanding list of conditions, although lead dysfunction is seen as a fairly common complication in active young patients. Guidelines for device implantation have been developed, but the weight of evidence remains somewhat limited by the paucity of pediatric data in this field.

SUMMARY

Thanks to refinements in lead design and generator technology, coupled with rapidly expanding clinical indications, pacemakers and implantable defibrillators have become increasingly important components of cardiac therapy for young patients. Expanded multicenter clinical studies will be needed to develop more objective guidelines for use of this advanced technology.