Sabrina Tsao

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.

Impact of the permanent ventricular pacing site on left ventricular function in children: a retrospective multicentre survey.

Background Chronic right ventricular (RV) pacing is associated with deleterious effects on cardiac function. Objective In an observational multicentre study in children with isolated atrioventricular (AV) block receiving chronic ventricular pacing, the importance of the ventricular pacing site on left ventricular (LV) function was investigated. Methods Demographics, maternal autoantibody status and echocardiographic measurements on LV end-diastolic and end-systolic dimensions and volumes at age <18 years were retrospectively collected from patients undergoing chronic ventricular pacing (>1 year) for isolated AV block. LV fractional shortening (LVFS) and, if possible LV ejection fraction (LVEF) were calculated. Linear regression analyses were adjusted for patient characteristics. Results From 27 centres, 297 children were included, in whom pacing was applied at the RV epicardium (RVepi, n=147), RV endocardium (RVendo, n=113) or LV epicardium (LVepi, n=37). LVFS was significantly affected by pacing site (p=0.001), and not by maternal autoantibody status (p=0.266). LVFS in LVepi (39±5%) was significantly higher than in RVendo (33±7%, p<0.001) and RVepi (35±8%, p=0.001; no significant difference between RV-paced groups, p=0.275). Subnormal LVFS (LVFS<28%) was seen in 16/113 (14%) RVendo-paced and 21/147 (14%) RVepi-paced children, while LVFS was normal (LVFS≥28%) in all LVepi-paced children (p=0.049). These results are supported by the findings for LVEF (n=122): LVEF was <50% in 17/69 (25%) RVendo- and in 10/35 (29%) RVepi-paced patients, while LVEF was ≥50% in 17/18 (94%) LVepi-paced patients. Conclusion In children with isolated AV block, permanent ventricular pacing site is an important determinant of LV function, with LVFS being significantly higher with LV pacing than with RV pacing.

Arrhythmia Surgery in Patients With and Without Congenital Heart Disease

BACKGROUND Arrhythmia surgery has favorably impacted the clinical course of debilitating atrial and ventricular arrhythmias in patients with and without congenital heart disease. This study reviews arrhythmia mechanisms and documents long-term outcome of patients undergoing arrhythmia operations alone or associated with congenital heart repairs. The analysis excludes Fontan conversion patients. METHODS Between 1987 and 2007, arrhythmia operations were done in 11 patients without associated congenital heart disease and in 89 along with congenital heart repairs. Mean age was 15.9 +/- 12.5 years (range, 7 days-48 years); 7 were infants (mean age, 23 +/- 16 days). Resternotomy was performed in 65 (65%). Two functional ventricles were present in 67 patients; 33 had 1 functional ventricle. Arrhythmias included macro-reentrant atrial tachycardia in 45, atrial fibrillation in 11, accessory connections in 19, atrioventricular nodal reentry tachycardia in 6, focal atrial tachycardia in 6, and ventricular tachycardia in 13. RESULTS Operative mortality was 3 (3.0%) due to advanced associated congenital heart disease. There were 4 late deaths (4.0%) and 2 late cardiac transplants (2.0%). Freedom from arrhythmia recurrence at 1 and 10 years was 94% and 85% for atrial arrhythmias, and 85% and 68% for ventricular arrhythmias, respectively. CONCLUSIONS Successful surgical therapy for atrial arrhythmias can be performed safely with a high freedom from recurrence rate in patients with and without associated congenital heart disease. Surgical ablation for ventricular arrhythmias is less predictive. Complexity of the underlying congenital heart disease and hemodynamic status may contribute to potential arrhythmia recurrence or new onset arrhythmia manifestation.

Extracardiac Versus Intra-Atrial Lateral Tunnel Fontan: Extracardiac is Better

This article was prepared to summarize the points made in a debate that the first author (C.L.B.) had with Dr. Richard Jonas at the American Association for Thoracic Surgery 90th Annual Meeting. The topic of the debate was the optimal surgical approach for functional single-ventricle patients: extracardiac versus intra-atrial lateral tunnel Fontan. My role was to take the viewpoint that the extracardiac Fontan is better. This review summarizes our results at Childrens Memorial Hospital (Chicago, IL) with 180 patients undergoing a primary Fontan procedure and 126 patients undergoing an extracardiac Fontan as part of a Fontan conversion. The world literature was reviewed on outcomes following the Fontan procedure, focusing on six main areas supporting the superiority of the extracardiac Fontan: hemodynamics, arrhythmias, applicability to complex anatomy, use of cardiopulmonary bypass, complications of fenestration and thromboembolism, and operative mortality. Based on this review, it is our conclusion that the extracardiac Fontan is the procedure of choice for patients with a functional single ventricle based on a very low operative mortality, a lower incidence of early and late arrhythmias, improved hemodynamics, fewer postoperative complications, and applicability to a wide variety of complex cardiac anatomy.

Maze Procedure in Single Ventricle Patients

As of September 2007, 120 patients have undergone a Fontan conversion procedure at Childrens Memorial Hospital (Chicago, IL). One of the primary indications for surgery in these patients has been arrhythmias, either atrial reentry tachycardia or atrial fibrillation. The surgical treatment of those two lesions has been with the modified right atrial maze and the Cox-maze III. The purpose of this review is to describe our strategy for performing the maze procedure in these single-ventricle patients. The primary tool for performing the maze in this series has been with the cryocatheter with cryoablation at -160 degrees C for 1 minute. These cryoablation lesions have been combined with standard surgical incisions in the right and left atria. The early mortality in this series is 1%, late mortality is 5%. Freedom from atrial reentry tachycardia recurrence at 5 years is 86%. Freedom from atrial fibrillation recurrence is 98% at 5 years.

Intermediate-Term Outcome of 140 Consecutive Fontan Conversions With Arrhythmia Operations.

BACKGROUND Atrial arrhythmias and progressive circulatory failure frequently develop in patients with a Fontan circulation. Improvement of flow dynamics and revision of the arrhythmia substrate may improve outcomes in selected patients. We sought to determine intermediate-term outcomes after Fontan conversion with arrhythmia operations and identify characteristics associated with decreased transplant-free survival. METHODS The first 140 Fontan conversions with arrhythmia operations at a single institution were analyzed for predictors of cardiac death or transplant and incidence of arrhythmia recurrence. RESULTS The median age at the Fontan conversion operation was 23.2 years (range, 2.6 to 47.3 years). Preoperative arrhythmias were present in 136 patients: right atrial tachycardia in 48 patients, left atrial tachycardia in 21, and atrial fibrillation in 67. Freedom from cardiac death or transplant was 90% at 5 years, 84% at 10 years, and 66% at 15 years. The median age at the last follow-up among survivors was 32 years (range, 15 to 61 years). By multivariable analysis, risk factors for cardiac death or heart transplantation were a right or indeterminate ventricular morphology, cardiopulmonary bypass time exceeding 240 minutes, ascites, protein-losing enteropathy, or a biatrial arrhythmia operation at the time of conversion. Freedom from recurrence of atrial tachycardia was 77% at 10 years. Among 67 patients with atrial fibrillation undergoing biatrial arrhythmia operations, none had recurrent atrial fibrillation. CONCLUSIONS Freedom from cardiac death or transplant for patients undergoing Fontan conversion with an arrhythmia operation is 84% at 10 years. The effects of atrial arrhythmia operations are durable in most patients. These outcomes may serve as useful benchmarks for alternative management strategies.

Device management of arrhythmias after Fontan conversion

OBJECTIVES We assessed our pacemaker strategy, use of antitachycardia therapies, generator longevity, and need for programming changes in patients having Fontan conversion with arrhythmia surgery. METHODS Between 1994 and 2008, of 121 consecutive patients having Fontan conversion and arrhythmia surgeries, 120 patients underwent pacemaker implantation at the time of Fontan conversion (mean age 22.9 +/- 8.1 years). Prior pacemakers were in place in 32/120 (26.7%) patients. Between 1994 and 1998, single-chamber atrial antitachycardia pacemakers were implanted (n = 12); atrial rate-responsive pacemakers (n = 31) were implanted between 1998 and 2002. Dual-chamber rate-responsive pacemakers (n = 16) were used between 2002 and 2003, and subsequently dual-chamber antitachycardia pacemakers (n = 61) have become the pacemaker of choice. Leads have evolved from transatrial endocardial leads to epicardial unipolar and subsequently bipolar leads. RESULTS Among 87 patients with adequate follow-up, all are currently atrially paced at a minimum lower rate > or =70 beats per minute. Single-chamber atrial pacemakers were implanted in 43 (antitachycardia in 12), and dual-chamber pacemakers in 77 (antitachycardia in 61); multisite ventricular leads were placed in 7 patients. Far-field R-wave sensing in 78.6% of unipolar atrial leads led to use of epicardial bipolar leads. Late atrioventricular block (24%) led to routine implantation of dual-chamber pacemakers. Antitachycardia pacing was utilized in 7%. One patient required acute lead revision and 4 required late upgrade to dual-chamber pacemakers. There was no pacemaker-related infection. Twenty patients required generator change, and the mean device longevity was 7.53 years. CONCLUSIONS Customized pacemaker therapy can optimize management of patients following Fontan conversion. Device longevity is excellent. Based on our experience with 120 Fontan conversions, we recommend placement of a dual-chamber antitachycardia pacemaker with bipolar steroid-eluting epicardial leads in all patients at the time of the conversion.

Prophylactic atrial arrhythmia surgical procedures with congenital heart operations: review and recommendations.

Specific congenital heart anomalies significantly increase the risk for late atrial arrhythmias, raising the question whether prophylactic arrhythmia operations should be incorporated into reparative open heart procedures. Currently no consensus exists regarding standard prophylactic arrhythmia procedures. Questions remain concerning the arrhythmia-specific lesions to perform, energy sources to use, need for atrial appendectomy, and choosing a right, left, or biatrial Maze procedure. These considerations are important because prophylactic arrhythmia procedures are performed without knowing if the patient will actually experience an arrhythmia. This review identifies congenital defects with a risk for the development of atrial arrhythmias and proposes standardizing lesion sets for prophylactic arrhythmia operations.

The multicenter pediatric and adult congenital EP quality (MAP-IT) initiative-rationale and design: Report from the pediatric and congenital electrophysiology society's MAP-IT taskforce

Multicenter clinical registries are increasingly recognized as valuable tools for establishing benchmarks, facilitating patient-centered quality improvement and research. In 2010, the Pediatric and Congenital Electrophysiology Society convened a taskforce of its members to design, construct, and implement a clinical registry known as the Multicenter Pediatric and Adult Congenital EP Quality (MAP-IT) Initiative. The present aim of the MAP-IT Initiative is to create an infrastructure by which we can measurably improve patient-centered outcomes and reduce complications associated with electrophysiology studies and catheter ablation in pediatric and congenital heart disease patients. The purpose of this writing is to report the progress to date from three of the four subcommittees of the MAP-IT taskforce. Specifically, we present our initial set of key data elements and definitions, recommended database table structure, and considerations regarding wide-scale implementation of the registry. Development of a risk/complexity score for use in the MAP-IT registry is presented in a separate companion manuscript. It is our intent that these manuscripts will serve to introduce the electrophysiology and pediatric cardiology community to the MAP-IT initiative and provide a rationale for its design and recommended implementation strategy.

Percutaneous, Ultrasound-Guided Stellate Ganglion Nerve Block Suppresses Recurrent Ventricular Fibrillation in an Infant Awaiting Heart Transplant

Percutaneous stellate ganglion nerve block has been used to treat chronic pain syndromes. It has been described for refractory ventricular arrhythmias.1,2 However, it has rarely been described in an infant.3,4 To the best of our knowledge, this block has not been used at this age as a diagnostic challenge and therapeutic bridge to surgical left cardiac sympathetic denervation (LCSD) and cardiac transplant. This patient presented shortly after birth with orthodromic reciprocating tachycardia and ventricular preexcitation. She was treated with propranolol and discharged. Three months later, she became rigid and cyanotic at home, requiring cardiopulmonary resuscitation, cardioversion, and amiodarone for ventricular tachycardia (VT). She underwent electrophysiology study with successful ablation of her accessory connection, but in the following days she developed recurrent ventricular fibrillation. Magnetic resonance imaging revealed asymmetric left ventricular hypertrophy, otherwise normal anatomy and no focal lesions; catheterization was nondiagnostic. An epicardial implantable cardioverter-defibrillator (ICD) was placed 13 days after presentation, and she was discharged home on amiodarone and propranolol. At 7 months of age, she had 28 appropriate shocks for monomorphic VT, polymorphic VT, and ventricular fibrillation over 3 days, …