Cardiac Resynchronization Therapy in Pediatric and Congenital Heart Disease

Long-Term Outcome of Patients With Congenital Heart Disease Undergoing Cardiac Resynchronization Therapy

Background

Cardiac resynchronization therapy (CRT) is rarely used in patients with congenital heart disease, and reported follow‐up is short. We sought to evaluate long‐term impact of CRT in a single‐center cohort of patients with congenital heart disease.

Methods and Results

Thirty‐two consecutive patients with structural congenital heart disease (N=30) or congenital atrioventricular block (N=2), aged median of 12.9 years at CRT with pacing capability device implantation, were followed up for a median of 8.7 years. CRT response was defined as an increase in systemic ventricular ejection fraction or fractional area of change by >10 units and improved or unchanged New York Heart Association class. Freedom from cardiovascular death, heart failure hospitalization, or new transplant listing was 92.6% and 83.2% at 5 and 10 years, respectively. Freedom from CRT complications, leading to surgical system revision (elective generator replacement excluded) or therapy termination, was 82.7% and 72.2% at 5 and 10 years, respectively. The overall probability of an uneventful therapy continuation was 76.3% and 58.8% at 5 and 10 years, respectively. There was a significant increase in ejection fraction/fractional area of change (P<0.001) mainly attributable to patients with systemic left ventricle (P=0.002) and decrease in systemic ventricular end‐diastolic dimensions (P<0.05) after CRT. New York Heart Association functional class improved from a median 2.0 to 1.25 (P<0.001). Long‐term CRT response was present in 54.8% of patients at last follow‐up and was more frequent in systemic left ventricle (P<0.001).

Conclusions

CRT in patients with congenital heart disease was associated with acceptable survival and long‐term response in ≈50% of patients. Probability of an uneventful CRT continuation was modest.

Successful Treatment of an Infant with Left Ventricular Noncompaction Presenting with Fatal Ventricular Arrhythmia Treated with Cardiac Resynchronization Therapy and an Implantable Cardioverter Defibrillator

We herein report the successful treatment of a 4-year-old girl with left ventricular noncompaction (LVNC) who presented with incessant ventricular fibrillation at 5 months of age. An implantable cardioverter defibrillator (ICD) was implanted, and dual chamber (DDD) pacing was initiated at 7 months of age. At her 10-month follow-up, her left ventricular ejection fraction (LVEF) had decreased from 45% to 20% with mechanical dyssynchrony. After upgrading to cardiac resynchronization therapy (CRT), the LVEF improved to 50%. The usefulness of CRT in pediatric LVNC has not been fully elucidated. However, our case suggests that CRT therapy may be an effective option for LVNC-induced cardiac dysfunction.

Cardiac resynchronization therapy in congenital heart disease

Cardiac resynchronization therapy (CRT) is an established treatment option for adult patients suffering heart failure due to idiopathic or ischemic cardiomyopathy associated with electromechanical dyssynchrony. There is limited evidence suggesting similar efficacy of CRT in patients with congenital heart disease (CHD). Due to the heterogeneity of structural and functional substrates, CRT implantation techniques are different with a thoracotomy or hybrid approach prevailing. Efficacy of CRT in CHD seems to depend on the anatomy of the systemic ventricle with best results achieved in systemic left ventricular patients upgraded to CRT from conventional pacing. Indications for CRT in patients with CHD were recently summarized in the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS) Expert Consensus Statement on the Recognition and Management of Arrhythmias in Adult Congenital Heart Disease and are presented in the text.

Advances in the Care of Adults With Congenital Heart Disease

The significant decline in mortality among children and adolescents with congenital heart disease (CHD) is associated with an increasing prevalence of CHD in adults, particularly those with moderate to severe defects. As a significant percentage of adolescents and young adults are lost to follow-up in the transition from pediatric to adult care, they may present for elective procedures with substantial CHD-associated morbidity. In addition to the specific cardiac defect, the procedures performed, and the current pathophysiological status, several factors should be considered when managing the adult with CHD. These include the type of setting (adult vs pediatric institution); surgeon (pediatric vs adult cardiac surgeon); coexisting diseases associated with CHD, such as coronary artery disease, hepatic dysfunction, renal dysfunction, cerebrovascular accidents, myopathy, and coagulation disorders; acquired diseases of aging; pregnancy; and psychosocial functioning. The current status of the management of common and important congenital cardiac defects is also described.

Remote monitoring leads to early recognition and treatment of critical arrhythmias in adults after atrial switch operation for transposition of the great arteries

BACKGROUND

Adults with transposition of the great arteries (TGA) after atrial switch repair have an increased risk for arrhythmia and sudden cardiac death. We analyzed whether a remote monitoring (RM) system as part of an implantable cardiac device contributes to timely recognition and improved treatment of critical arrhythmias in these patients.

METHODS AND RESULTS

All consecutive TGA patients (n=11) requiring a pacemaker or cardiac resynchronization therapy with or without implantable cardioverter defibrillator between 2008 and 2011 were included. RM-detected arrhythmia, abnormality of device integrity and reaction time from event transmission until acknowledgement via email and clinical decision making were analyzed and compared to a control group (n=21). In 10 patients (91%) 17 arrhythmias were detected, 8 patients (80%) indicated no symptoms. In the RM group time interval from transmission to acknowledgement was 2.4 days (range, 0-4.5 days). Clinical decision-making was advanced by a mean of 77.5 days (range, 10-197 days) compared with conventional follow-up and identified adaption of anti-arrhythmic medication in 8, electrical cardioversion in 2, overdrive pacing in 1 and radiofrequency ablation in 2 patients. A coronary sinus lead fracture was identified in 1 patient followed by successful replacement.

CONCLUSIONS

 RM enables early detection of tachyarrhythmia followed by optimization of medical treatment and potentially life-saving anti-tachycardic intervention in adults after atrial repair of TGA.  

Permanent cardiac pacing in children: choosing the optimal pacing site: a multicenter study

BACKGROUND

We evaluated the effects of the site of ventricular pacing on left ventricular (LV) synchrony and function in children requiring permanent pacing.

METHODS AND RESULTS

One hundred seventy-eight children (aged <18 years) from 21 centers with atrioventricular block and a structurally normal heart undergoing permanent pacing were studied cross-sectionally. Median age at evaluation was 11.2 (interquartile range, 6.3-15.0) years. Median pacing duration was 5.4 (interquartile range, 3.1-8.8) years. Pacing sites were the free wall of the right ventricular (RV) outflow tract (n=8), lateral RV (n=44), RV apex (n=61), RV septum (n=29), LV apex (n=12), LV midlateral wall (n=17), and LV base (n=7). LV synchrony, pump function, and contraction efficiency were significantly affected by pacing site and were superior in children paced at the LV apex/LV midlateral wall. LV dyssynchrony correlated inversely with LV ejection fraction (R=0.80, P=0.031). Pacing from the RV outflow tract/lateral RV predicted significantly decreased LV function (LV ejection fraction <45%; odds ratio, 10.72; confidence interval, 2.07-55.60; P=0.005), whereas LV apex/LV midlateral wall pacing was associated with preserved LV function (LV ejection fraction ≥55%; odds ratio, 8.26; confidence interval, 1.46-47.62; P=0.018). Presence of maternal autoantibodies, gender, age at implantation, duration of pacing, DDD mode, and QRS duration had no significant impact on LV ejection fraction.

CONCLUSIONS

The site of ventricular pacing has a major impact on LV mechanical synchrony, efficiency, and pump function in children who require lifelong pacing. Of the sites studied, LV apex/LV midlateral wall pacing has the greatest potential to prevent pacing-induced reduction of cardiac pump function.

Pacing device therapy in infants and children: a review

The number of pediatric pacemakers implanted is still relatively small. Children requiring pacing therapy have characteristics that are distinct from those of adults, including physical size, somatic growth, and cardiac anomalies. Considering these features, long-term follow-up of pediatric pacemaker implantation is necessary. Selection of appropriate generators, pacing modes, pacing sites, and leads is important. Generally, epicardial leads are commonly used in small infants. On the other hand, the use of endocardial leads in children is increasing worldwide because of their benefits over epicardial leads, such as minimal invasiveness, lower pacing threshold, and longer generator longevity. Endocardial leads are not suitable for patients with intracardiac shunts because of the high risk of systemic thrombosis. Venous occlusion is another significant problem with endocardial leads. With the increase in the number of pacing device implantations, the incidence of infection from such devices is also increasing. Complete device removal is sometimes recommended to treat device infection, but experience in the removal of endocardial leads in children is still scarce. This article gives an overview of pacing therapy in the pediatric population, including discussions on new pacing systems, such as remote monitoring systems, magnetic imaging compliant pacemaker systems, and leadless pacing devices.

Synchronicity of systolic deformation in healthy pediatric and young adult subjects: a two-dimensional strain echocardiography study

Two-dimensional speckle tracking echocardiography (2DSTE) offers valuable information in the echocardiographic assessment of ventricular myocardial function. It enables the quantification and timing of systolic ventricular myocardial deformation. In addition, 2DSTE can be used to identify mechanical dyssynchrony, which is an important parameter in predicting the response to cardiac resynchronization therapy for heart failure. Detailed knowledge of normal timing of systolic deformation and its degree of synchronicity in children is lacking. We aimed to establish the normal timing of left ventricular myocardial systolic deformation using 2DSTE in a large cohort of healthy children and young adults. Transthoracic echocardiograms were acquired in 195 healthy subjects (139 children and 56 young adult <40 yr of age) and were retrospectively analyzed. Time to peak systolic longitudinal, circumferential, and radial strain was determined by means of speckle tracking. Strong, statistically significant relations between age as well as various anthropometric variables (e.g., heart rate) and timing of systolic deformation ( P < 0.0001) were present. The extent of dyssynchronous deformation increased with age. This is the first report that establishes reference values per cardiac segment for time to peak systolic myocardial strain values in all three directions assessed with 2DSTE in a large pediatric and young adult cohort. We emphasize the need for using age-specific reference values as well as heart rate correction for the adequate interpretation of 2DSTE measurements.

Echocardiographic evaluation of the single right ventricle in congenital heart disease: results of new techniques

Right ventricular (RV) function is increasingly recognized as having prognostic significance in various disease processes. The current gold standard for noninvasive measurement of RV function is cardiac magnetic resonance imaging; however, because of practical considerations, echocardiography remains the most often used modality for evaluating the RV. In the past, because of its complex morphology, echocardiographic assessment of the RV was usually qualitative in nature. Current advances in echocardiographic techniques have been able to overcome some of the previous limitations and thus quantification of RV function is increasingly being performed. In addition, recent echocardiographic guidelines for evaluating the RV have been published to aid in standardizing practice. The evaluation of RV function almost certainly has no greater importance than in the congenital heart population, especially in those patients that have a single RV acting as the systemic ventricle. As this complex population continues to increase in number, accurate and precise evaluation of RV function will be a major issue in determining clinical care.

Chronic ventricular pacing in children: toward prevention of pacing-induced heart disease

In children with congenital or acquired complete atrioventricular (AV) block, ventricular pacing is indicated to increase heart rate. Ventricular pacing is highly beneficial in these patients, but an important side effect is that it induces abnormal electrical activation patterns. Traditionally, ventricular pacemaker leads are positioned at the right ventricle (RV). The dyssynchronous pattern of ventricular activation due to RV pacing is associated with an acute and chronic impairment of left ventricular (LV) function, structural remodeling of the LV, and increased risk of heart failure. Since the degree of pacing-induced dyssynchrony varies between the different pacing sites, ‘optimal-site pacing’ should aim at the prevention of mechanical dyssynchrony. Especially in children, generally paced from a very early age and having a perspective of life-long pacing, the preservation of cardiac function during chronic ventricular pacing should take high priority. In the perspective of the (patho)physiology of ventricular pacing and the importance of the sequence of activation, this paper provides an overview of the current knowledge regarding possible alternative sites for chronic ventricular pacing. Furthermore, clinical implications and practical concerns of the various pacing sites are discussed. The review concludes with recommendations for optimal-site pacing in children.

Cardiac resynchronization therapy in children

Cardiac Resynchronization therapy has become an important management tool in adults with heart failure and dilated cardiomyopathy. The role of CRT in children with CHF is still unclear. Evidence is slowly emerging in the pediatric cardiology literature that CRT may have an important and useful role in certain select populations with CHF. These include patients with complete heart block who develop pacing-induced cardiomyopathy, certain forms of congenital heart disease associated with systemic ventricular failure (even if the systemic ventricle is a morphologic RV) and in patients with idiopathic dilated cardiomyopathy. Studies in children supporting the use of CRT include many case reports, a few studies of CRT in post-operative patients, and one multi-center registry reporting the use of CRT in children. These papers will be summarized.

Echocardiographic tools for pacemaker optimization of ventricular function in an infant following surgical repair for double outlet right ventricle

A case of an infant, following surgical repair for double outlet right ventricle, who developed low cardiac output syndrome and complete heart block that required insertion of a pacemaker is presented. The infant underwent optimization of his ventricular function to determine whether pacing the right ventricle or left ventricle or both would improve cardiac function. Using standard two-dimensional echocardiography and Doppler imaging, tissue synchronization imaging, and two-dimensional speckle-tracking strain analysis, improvement in cardiac output and function was demonstrated. The present case highlights the usefulness of newer echocardiographic techniques in pacemaker optimization in the acute postoperative setting.

Effective cardiac resynchronization therapy for an adolescent patient with dilated cardiomyopathy seven years after mitral valve replacement and septal anterior ventricular exclusion

Cardiac resynchronization therapy (CRT) is a new treatment for refractory heart failure. However, most heart failure patients treated with CRT are middle-aged or old patients with idiopathic or ischemic dilated cardiomyopathy. We treated a 17 year 11 month old girl with dilated cardiomyopathy after mitral valve replacement (MVR) and septal anterior ventricular exclusion (SAVE). Seven years after the SAVE procedure, she presented complaining of palpitations and general fatigue with normal activity. Her echocardiogram showed reduced left ventricular function. Despite of optimal medical therapy, her left ventricular function continued to decline and she experienced regular arrhythmias such as premature ventricular contractions. We thus elected to perform cardiac resynchronization therapy with defibrillator (CRT-D). After CRT-D, her clinical symptoms improved dramatically and left ventricular ejection fraction (LVEF) improved from 31.2% to 51.3% as assessed by echocardiogram. Serum BNP levels decreased from 448.2 to 213.6 pg/ml. On ECG, arrhythmias were remarkably reduced and QRS duration was shortened from 174 to 152 msec. In conclusion, CRT-D is an effective therapeutic option for adolescent patients with refractory heart failure after left ventricular volume reduction surgery.

Clinical practice: heart failure in children. Part II: current maintenance therapy and new therapeutic approaches

The current maintenance treatment for children with heart failure remains controversial: To a large extent, it is based on extrapolation of data derived from trials in adult populations. There are only a few randomized trials focused on the treatment of children with cardiac disease, especially in the subgroup with cardiomyopathy and heart failure. The goals of therapy are to maintain circulatory and end-organ function and to allow for recovery and reverse remodeling to occur. When maintenance therapy fails and medical treatment does not result in clinical improvement, the alternative of device therapy must be considered: In that case, the usual aim is to stabilize circulatory status, as a bridge to either recovery or to cardiac transplantation. Recently, carefully selected patients with electromechanical dyssynchrony of ventricular systolic function have demonstrated a benefit from biventricular pacing devices (cardiac resynchronization therapy), with improved functional capacity and quality of life and, in some patients, avoidance of the need for transplantation.

Does biventricular pacing improve hemodynamics in children undergoing routine congenital heart surgery?

Biventricular (BiV) pacing or cardiac resynchronization therapy (CRT) is an established therapy for heart failure in adults. In children, cardiac dyssynchrony occurs most commonly following repair of congenital heart disease (CHD) where multisite pacing has been shown to improve both hemodynamics and ventricular function. Determining which patient types would specifically benefit has not yet been established. A prospective, repeated measures design was undertaken to evaluate BiV pacing in a cohort of children undergoing biventricular repair for correction of their CHD. Hemodynamics, arterial blood gas, electrocardiographic (ECG), and echocardiographic data were collected. Pacing protocol was undertaken prior to the patient's extubation with 20 min of conventional right ventricular (RV) or BiV pacing, preceded and followed by 10 min of recovery time. Multivariate statistics were used to analyze the data with p values <0.05 considered significant. Twenty-five (14 female) patients underwent surgery at a median (range) age of 5.2 (0.1-37.4) months with no early mortality. The Risk-adjusted classification for Congenital Heart Surgery (RACHS) scores were 2 in 14 patients, 3 in eight patients, and 4 in three patients. None had pre-existing arrhythmias, dyssynchrony, or required pacing pre-operatively. No patient required implantation of a permanent pacemaker post-operatively. The median cardio-pulmonary bypass time was 96 (55-236) min. RV and BiV pacing did not improve cardiac index from baseline (3.23 vs. 3.42 vs. 3.39 L/min/m2; p > 0.05). The QRS duration was not changed with pacing (100 vs. 80 vs. 80 ms; p > 0.05). On echocardiography, the time-to-peak velocity difference between the septal and posterior walls (synchrony) during pacing was similar to baseline and was also not statistically significant. BiV pacing did not improve cardiac output when compared to intrinsic sinus rhythm or RV pacing in this cohort of patients. Our study has shown that BiV pacing is not indicated in children who have undergone routine BiV congenital heart surgery. Further prospective studies are needed to assess the role of multisite pacing in children with ventricular dyssynchrony such as those with single ventricles, those undergoing reoperation or those with high RACHS scores.