Effects of remifentanil anesthesia on cardiac electrophysiologic properties in children undergoing catheter ablation of supraventricular tachycardia.

Remifentanil is commonly used during anesthesia in pediatric electrophysiologic studies (EPS). The purpose of this study is to determine the effects of remifentanil on the cardiac electrophysiologic properties of children undergoing ablation of supraventricular tachycardia (SVT). A prospective study was performed in patients undergoing EPS before ablation of SVT. Each patient received two different anesthetic protocols: protocol 1 = propofol (200 mcg/kg/min) and protocol 2 = propofol (120 mcg/kg/min) plus remifentanil (0.3 mcg/kg/min). EPS data were measured during the steady state of each protocol. Paired Student t test was performed for analysis of continuous data. All p values <0.05 were considered statistically significant. Fifteen patients were enrolled between April 2005 and January 2006. The mean age was 13.3 ± 2.9 years (range 6.7 to 17.7). Seven patients had atrioventricular (AV) nodal re-entry tachycardia; 5 patients had Wolff-Parkinson-White syndrome; 2 patients had a concealed accessory pathway; and 1 patient was not inducible. Of the 14 patients who underwent ablation, 13 (93%) achieved successful. The baseline sinus cycle length extended from 884 ± 141 ms during protocol 1 to 980 ± 165 ms during protocol 2 (p = 0.01), and the Wenckebach cycle length lengthened from 377 ± 96 ms to 406 ± 109 ms (p = 0.01). No other variables measured (atrial-His (AH) and His-ventricular (HV) interval, atrioventricular node (AVN), and atrial, ventricular, and accessory pathway effective refractory periods) changed significantly between the two different protocols. In pediatric patients undergoing EPS before ablation of SVT, remifentanil appears to slow both sinus and AV nodal function. These effects should be taken into consideration when performing EPS.

Pacing-induced electromechanical ventricular dyssynchrony does not acutely influence right ventricular function and global hemodynamics in children with normal hearts.

BACKGROUND: Right ventricular (RV) pacing may be detrimental to ventricular function. However, the acute effects of electromechanical dyssynchrony on RV function are not well characterized in children. We studied acute effects of electromechanical dyssynchrony, induced by RV apical and RV outflow pacing, in children with normal hearts, evaluating electromechanical synchrony, hemodynamic response, and RV function. METHODS: Seventeen children (mean +/- SD, 12 +/- 4 years) with normal cardiac structure/function were paced after accessory pathway ablation, at baseline (AOO), and with AV pacing (DOO) from the RV apex and RV outflow. QRS duration was determined from surface ECG. Intra- and interventricular mechanical dyssynchrony and regional ventricular function were determined using tissue Doppler imaging. Global RV systolic and diastolic functions were assessed by RV dP/dT(max) and RV dP/dT(neg) using pressure-tipped transducers. Regional RV function was assessed by tissue Doppler imaging. Cardiac index (CI) and blood pressures were measured. RESULTS: RV apical and outflow pacing induced significant electromechanical dyssynchrony manifested by lengthening of the QRS duration, increased LV intraventricular delay (49 +/- 34 ms, 53 +/- 43 ms, respectively, P < 0.001), and increased interventricular delay (60 +/- 29 ms, 55 +/- 37 ms, P < 0.0001) versus AOO pacing. However, there was no change in blood pressure, CI, RV dp/dT(max), RV dP/dT(neg), or regional tissue Doppler velocities, indicating preserved hemodynamics and preserved global and regional RV systolic and diastolic function. CONCLUSIONS: In children with normal cardiac function and structure, pacing-induced electromechanical dyssynchrony did not acutely affect RV systolic and diastolic function and did not acutely alter global hemodynamics. Therefore, electromechanical dyssynchrony may only be an important therapeutic target in the setting of decreased RV function.

The effects of dexmedetomidine on cardiac electrophysiology in children.

BACKGROUND: Dexmedetomidine (DEX) is an alpha2-adrenergic agonist that is approved by the Food and Drug Administration for short-term (<24 h) sedation in adults. It is not approved for use in children. Nevertheless, the use of DEX for sedation and anesthesia in infants and children appears to be increasing. There are some concerns regarding the hemodynamic effects of the drug, including bradycardia, hypertension, and hypotension. No data regarding the effects of DEX on the cardiac conduction system are available. We therefore aimed to characterize the effects of DEX on cardiac conduction in pediatric patients. METHODS: Twelve children between the ages of 5 and 17 yr undergoing electrophysiology study and ablation of supraventricular accessory pathways had hemodynamic and cardiac electrophysiologic variables measured before and during administration of DEX (1 microg/kg IV over 10 min followed by a 10-min continuous infusion of 0.7 microg x kg(-1) x h(-1)). RESULTS: Heart rate decreased while arterial blood pressure increased significantly after DEX administration. Sinus node function was significantly affected, as evidenced by an increase in sinus cycle length and sinus node recovery time. Atrioventricular nodal function was also depressed, as evidenced by Wenckeback cycle length prolongation and prolongation of PR interval. CONCLUSION: DEX significantly depressed sinus and atrioventricular nodal function in pediatric patients. Heart rate decreased and arterial blood pressure increased during administration of DEX. The use of DEX may not be desirable during electrophysiology study and may be associated with adverse effects in patients at risk for bradycardia or atrioventricular nodal block.

Evaluation of the fetal QT interval using non-invasive fetal ECG technology.

Non-invasive fetal electrocardiography (NI-FECG) is a promising alternative continuous fetal monitoring method that has the potential to allow morphological analysis of the FECG. However, there are a number of challenges associated with the evaluation of morphological parameters from the NI-FECG, including low signal to noise ratio of the NI-FECG and methodological challenges for getting reference annotations and evaluating the accuracy of segmentation algorithms. This work aims to validate the measurement of the fetal QT interval in term laboring women using a NI-FECG electrocardiogram monitor. Fetal electrocardiogram data were recorded from 22 laboring women at term using the NI-FECG and an invasive fetal scalp electrode simultaneously. A total of 105 one-minute epochs were selected for analysis. Three pediatric electrophysiologists independently annotated individual waveforms and averaged waveforms from each epoch. The intervals measured on the averaged cycles taken from the NI-FECG and the fetal scalp electrode showed a close agreement; the root mean square error between all corresponding averaged NI-FECG and fetal scalp electrode beats was 13.6 ms, which is lower than the lowest adult root mean square error of 16.1 ms observed in related adult QT studies. These results provide evidence that NI-FECG technology enables accurate extraction of the fetal QT interval.

mHealth in pediatrics-finding healthcare solutions for the next generation.

Mobile health (mHealth) technologies have begun to transform the way clinicians deliver healthcare, with goals of greater patient engagement and improved health outcomes. However, the unique needs of pediatric populations are commonly neglected when novel technologies are designed. Constantly changing size and evolving developmental capabilities present a challenge for development of effective mHealth solutions for children. Parents and the greater healthcare community have a greater role in child health, placing demands on new technology to provide connected models of care. This summary provides the landscape of challenges and opportunities presented by the growing population of children who could be optimal candidates for properly tailored mHealth solutions.

A beginner's guide to digital health for ambulatory care clinicians.

Digital health technology is already playing a larger role in how healthcare consumers receive information about health concerns and how patients manage wellness and disease. The influence of mobile apps, wireless medical devices and other tools for patient monitoring will soon be felt in almost every physician practice. In an environment where regulatory standards are still in flux, some of these technologies are validated and reliable, others are not. We present the first in a series of systematic guidelines to assist physicians in navigating digital health technologies that they will encounter in the office setting.

Digital health tools for diabetes.

Digital health tools are providing patients with easier ways to keep track of their blood glucose levels and other key self-reported data, such as carbohydrates ingested, medication administered, and physical activity. Data are often uploaded into the cloud where physicians and other members of the care team can access them. Clinical studies are beginning to demonstrate efficacy of some of these tools, and Food and Drug Administration approval, when present, provides some much-needed validation. It is anticipated that these tools will continue to evolve and patient acceptance will continue to grow. Physician and care teams will need to familiarize themselves with the tools their patients are using and provide guidance and support for their use.

A management strategy for fetal immune-mediated atrioventricular block.

INTRODUCTION: The purpose of this study is to describe an in utero management strategy for fetuses with immune-mediated 2° or 3° atrioventricular (AV) block. METHODS AND RESULTS: The management strategy as applied to 29 fetuses consisted of three parts. First, using fetal echocardiography and obstetrical ultrasound, we assessed fetal heart rate (FHR), heart failure, growth and a modified biophysical profile score (BPS) assessing fetal movement, breathing and tone. Second, we treated all fetuses with transplacental dexamethasone, adding terbutaline if the FHR was<56 bpm. Digoxin and/or intravenous immune globulin (IVIG) was added for progressive fetal heart failure. Third, we delivered fetuses by cesarean section for specific indications that included abnormal BPS, maternal/fetal conditions, progression of heart failure, or term pregnancy. We assessed perinatal survival, predictors of delivery and maternal/fetal complications in 29 fetuses with 3° (n=23) or 2° (n=6) AV block. There were no fetal deaths. In utero therapy included dexamethasone (n=29), terbutaline (n=13), digoxin (n=3) and/or IVIG (n=1). Delivery indications included term gestation (66%), fetal/maternal condition (14%), low BPS (10%) and progression of fetal heart failure (10%). An abnormal BPS correlated with urgent delivery. CONCLUSION: These results suggest that applying this specific management strategy that begins in utero can improve perinatal outcome of immune-mediated AV block.

An expanded phenotype of maternal SSA/SSB antibody-associated fetal cardiac disease.

OBJECTIVES: Conventional manifestations of fetal Sjogren's antibodies (SSA/SSB) associated cardiac disease include atrioventricular block (AVB), transient sinus bradycardia, endocardial fibroelastosis (EFE) and dilated cardiomyopathy. We describe other manifestations of cardiac disease. METHODS: We describe three fetuses with unique myocardial and conduction system disease. RESULTS: One had isolated EFE with subsequent mitral and tricuspid valve chordal avulsion, the second had sinoatrial and infrahissian conduction system disease, and in both, neonatal progression to life threatening disease occurred. The third had sinus node dysfunction and atrial flutter. CONCLUSION: These findings expand the clinical phenotype of maternal SSA/SSB antibody associated fetal cardiac disease.

Acute effects of single-site pacing from the left and right ventricle on ventricular function and ventricular-ventricular interactions in children with normal hearts.

OBJECTIVE: We studied, as a physiological benchmark, acute effects of right ventricular (RV) apical, RV outflow, and left ventricular (LV) pacing in children with normal cardiac function on LV and RV function and ventricular-ventricular interactions. DESIGN: The design of the study was a prospective, acute intervention. SETTING: The study was conducted in a tertiary care electrophysiology laboratory. Population and Methods. Seven children (mean +/- SD, 12 +/- 4 years) were paced after accessory pathway ablation, at baseline (AOO), and with atrioventricular pacing (DOO) from the RV apex, RV outflow, and left ventricle. OUTCOME MEASURES: Right ventricular dP/dT(max) and RV dP/dT(neg) (high-fidelity transducer-tipped catheters, Millar Instruments, Houston, TX, USA), cardiac index (Fick), blood pressure, and QRS duration were measured at each pacing condition. Intra- and interventricular mechanical dyssynchrony, systolic- and diastolic peak tissue velocities, and isovolumic acceleration were recorded by tissue Doppler imaging at the lateral mitral, septal, and tricuspid annuli at each condition. Results at each pacing condition were compared by repeated-measures analysis of variance. Results. Pacing prolonged QRS duration, causing electrical dyssynchrony (86 +/- 19 ms [baseline], 141 +/- 44 ms [RV apex], 121 +/- 18 ms [RV outflow], and 136 +/- 34 ms [LV], P < .01). Right ventricular outflow pacing caused LV intraventricular delay (63 +/- 52 vs. 12 +/- 7 ms, P < .05). Right ventricular apical pacing caused interventricular delay (61 +/- 29 vs. 25 +/- 18 ms, P < .05). There were no significant changes in blood pressure, cardiac index, RV dp/dT(max), RV dP/dT(neg), regional tissue velocities, or isovolumic acceleration during any of the pacing conditions, indicating preserved ventricular function and hemodynamics. No important ventricular-ventricular interactions were seen. CONCLUSIONS: In children with normal cardiac anatomy and function, single-site RV apical, RV outflow, and LV pacing induce electromechanical dyssynchrony without significantly changing ventricular function or hemodynamics, or adversely affecting ventricular-ventricular interactions.

Risk stratification in the asymptomatic child with Wolff-Parkinson-White syndrome.

PURPOSE OF REVIEW: As the safety and efficacy of invasive electrophysiologic studies and ablation therapy in pediatrics improves, there has been a greater interest in developing adequate risk stratification criteria for the asymptomatic pediatric patient with Wolff-Parkinson-White syndrome. This review will discuss the recent literature regarding this debate. RECENT FINDINGS: Recent retrospective and prospective studies of Wolff-Parkinson-White syndrome in asymptomatic pediatric patients have shown that the well established adult criteria for risk stratification may not be applicable in children. Both symptomatic and asymptomatic children had similar accessory pathway effective refractory periods and supraventricular tachycardia inducibility in recent invasive electrophysiologic studies. The first attempt at prospective evaluation of the use of ablation therapy in asymptomatic adult and pediatric patients with the condition has sparked a debate as to the definition of a high-risk patient and the utility of ablation in the asymptomatic patient. SUMMARY: It is still controversial whether the established criteria for risk stratification in adults can be confidently applied to the pediatric patient. The majority of pediatric electrophysiologists use invasive electrophysiologic studies for risk stratification and selection of appropriate therapy. This clinical practice reflects the increasing prevalence and safety of electrophysiologic study and ablation. Further studies to better define indications for study and ablation are still necessary, however, to define accurate criteria for risk stratification in this difficult pediatric problem.