Improvements in Accuracy and Confidence in Rhythm Identification After Cardiac Surgery Using the AtriAmp Signals.

Objectives: Following cardiac surgery, 50% to 60% of patients with congenital heart disease will experience an arrhythmia. These arrhythmias are associated with increased morbidity and mortality. Therefore, rapid and accurate identification is paramount to the improvement of patient outcome. We hypothesize that the AtriAmp, a device which allows atrial electrogram (AEG) display on the bedside monitors, will increase provider accuracy and confidence in arrhythmia diagnosis. Design: A prospective observational study. Electrograms were collected from post-operative patients from the bedside monitors surface ECG and an AEG using the AtriAmp. A 12-question online survey was given to critical care and cardiology providers at 9 different programs across the country as well as being posted to the AAP SOCC fall newsletter. Six questions displayed signals from only the surface leads, while the other 6 showed the same arrhythmias with an AEG obtained from the AtriAmp. Answers were then evaluated for confidence and accuracy. A paired t-test along with mixed method modeling was used to assess the data. Setting: Cardiac pediatric ICU. Subjects: Providers in pediatric cardiology and pediatric critical care were evaluated on their ability to diagnose arrhythmias on surface ECG and AEG obtained from bedside monitor. Interventions: The accuracy and confidence of diagnosis of both surface and AEG signals were evaluated through an on-line survey. Results: Eighty-eight providers completed the survey. The study showed that interpreting with the AtriAmp signal, compared to the surface ECG only, significantly increased the accuracy (P = .002) and confidence in provider rhythm diagnosis (P < .001). Junctional ectopic tachycardia, sinus tachycardia, and complete heart block had the most significant increase in accuracy of diagnose when using the AtriAmp signal (P < .001, P = .002, P = .010, respectively). Conclusion: Use of the AtriAmp increased provider accuracy and confidence in post-operative rhythm diagnosis when compared to diagnosis using the surface electrograms only.

2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients.

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients: Executive summary.

Guidelines for the implantation of cardiac implantable electronic devices (CIEDs) have evolved since publication of the initial ACC/AHA pacemaker guidelines in 1984 [1]. CIEDs have evolved to include novel forms of cardiac pacing, the development of implantable cardioverter defibrillators (ICDs) and the introduction of devices for long term monitoring of heart rhythm and other physiologic parameters. In view of the increasing complexity of both devices and patients, practice guidelines, by necessity, have become increasingly specific. In 2018, the ACC/AHA/HRS published Guidelines on the Evaluation and Management of Patients with Bradycardia and Cardiac Conduction Delay [2], which were specific recommendations for patients >18 years of age. This age-specific threshold was established in view of the differing indications for CIEDs in young patients as well as size-specific technology factors. Therefore, the following document was developed to update and further delineate indications for the use and management of CIEDs in pediatric patients, defined as ≤21 years of age, with recognition that there is often overlap in the care of patents between 18 and 21 years of age. This document is an abbreviated expert consensus statement (ECS) intended to focus primarily on the indications for CIEDs in the setting of specific disease/diagnostic categories. This document will also provide guidance regarding the management of lead systems and follow-up evaluation for pediatric patients with CIEDs. The recommendations are presented in an abbreviated modular format, with each section including the complete table of recommendations along with a brief synopsis of supportive text and select references to provide some context for the recommendations. This document is not intended to provide an exhaustive discussion of the basis for each of the recommendations, which are further addressed in the comprehensive PACES-CIED document [3], with further data easily accessible in electronic searches or textbooks.

2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients.

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

Cardiovascular Collapse with Intravenous Amiodarone in Children: A Multi-Center Retrospective Cohort Study.

OBJECTIVE: To determine the incidence of cardiovascular collapse in children receiving intravenous (IV) amiodarone and to identify the population at risk. DESIGN: A multicenter study of patients ≤ 18 years of age who received intravenous amiodarone between January 2005 and December 2015. A retrospective analysis was performed to identify patients who developed cardiovascular collapse (bradycardia and/or hypotension). RESULTS: Of 456 patients who received amiodarone, cardiovascular collapse occurred in 47 patients (10%). Patient risk factors for collapse in a univariate analysis were as follows: age < 3 months (p = 0.04), depressed cardiac function (p < 0.001), blood pressure below 3rd percentile (p < 0.001), high lactate at baseline (p < 0.001). Administration risk factors included bolus administration (p = 0.04), and bolus administration over ≤ 20 min (p = 0.04). In multivariate analysis, age, baseline blood pressure less than 3rd percentile, and rapid bolus delivery were independent risk factors for cardiovascular collapse in the study group. The mortality rate was significantly higher in the collapse group (28% versus 8%). CONCLUSION: We found an association between IV amiodarone administration and the risk of developing cardiovascular collapse in a significant subset of children. Extreme caution and careful hemodynamic monitoring is recommended when using IV amiodarone in this population, especially in young infants, hemodynamically compromised patients, and in patients receiving rapid amiodarone bolus administration.

Junctional Ectopic Tachycardia Localization and Procedural Approach using Cryoablation.

BACKGROUND: Idiopathic junctional ectopic tachycardia (JET) may still be difficult to control with antiarrhythmic therapy. Transcatheter ablation can be challenging and may be associated with a high risk of unintended atrioventricular block. The objective of this manuscript is to report the procedural technique, the location of the successful ablation, and the procedural characteristics while utilizing 3D mapping for cryoablation of JET. METHODS: A retrospective analysis was performed on all patients who had undergone cryothermal ablation for the treatment of JET at a single center. Patient, arrhythmia, and procedural information and long-term outcomes were evaluated. RESULTS: Thirteen patients with JET were treated by cryothermal ablation. The JET arrhythmia burden varied greatly, generally with inadequate control on medications. Left ventricular dilation was present in three patients, and one patient had dilated cardiomyopathy. The median age at the time of procedure was 13 years, with median weight of 54.1 kg. The ectopic focus was ablated in 11/13 patients within the lower 2/3 of the triangle of Koch (TOK) with cryotherapy. Ablations, which were not successful, low in the TOK were associated with substantially longer procedures, and had a higher risk of recurrence. There was late resolution of the arrhythmia in two of three acutely unsuccessful ablations. There were no complications. CONCLUSION: In the majority of patients JET can be safely ablated with the use of cryotherapy. Foci not identified in the lower 2/3 of the TOK are associated with longer procedures, more lesions, and decreased chance for long-term success.

Pseudo-preexcitation is prevalent among patients with repaired complex congenital heart disease.

This study aimed to evaluate the prevalence of preexcitation and possible pseudo-preexcitation among patients undergoing complex congenital heart surgery at a single center. During a 6-year period (2007-2013), the study retrospectively reviewed the electronic medical records and electrocardiograms (ECGs) of 98 patients who had undergone complex cardiac surgery at the University of Iowa Children's Hospital. The presence and timing of delta waves or short PR interval were evaluated as well as the results of testing for the presence of an accessory pathway. The ECG of 17 patients (17.3%) showed delta waves. Eight of these patients also had a short PR interval. A significant majority of the 17 patients (n = 13) with delta waves showed hypoplastic left heart syndrome (HLHS), with atrioventricular canal defect and Ebstein's anomaly also represented. Two patients with delta waves had adenosine testing that showed antegrade conduction block, greatly reducing the likelihood of an accessory pathway. One patient with delta waves had an electrophysiology study demonstrating an accessory pathway, and the remaining patients had no additional testing for an accessory pathway. For 12 patients, the findings showed a short PR interval on at least one ECG with no evidence of delta waves. Delta waves were commonly seen in patients with HLHS and less commonly in patients with other diagnoses. The high prevalence of preexcitation in combination with our testing confirmed the lack of an accessory pathway in the presence of a delta wave, suggesting that pseudo-preexcitation may be a frequent finding. A short PR interval also was seen frequently in patients exhibiting HLHS, with and without the presence of a delta wave.

Finger volume pulse waveforms facilitate reliable assessment of heart rate variability, but not blood pressure variability or baroreflex function.

BACKGROUND: We sought to determine whether heart rate variability (HRV), blood pressure (BP) variability, and baroreceptor-heart rate reflex sensitivity can be reliably assessed using finger volume pulse waveforms obtained from the commercially available EndoPAT device. METHODS: Non-invasive BP (Finometer Pro as a non-invasive standard) and finger volume (EndoPAT) waveforms were recorded in 65 adults (37 ± 14 years; 60% female) and systolic BP and heart rate (HR) time series were derived after calibrating the EndoPAT signal based on systolic and diastolic BP values obtained by a sphygomomanometer. Transfer function analyses were performed to test for coherence between systolic BP and HR time series derived from the Finometer and EndoPAT devices. Time-domain HRV parameters, frequency domain HR and systolic BP variability parameters, and baroreflex sensitivity (sequence technique) were computed from Finometer- and EndoPAT-derived time series and intraclass correlation coefficients (ICC) were calculated. RESULTS: Squared coherence between systolic BP time series derived from the Finometer and EndoPAT devices was low, suggesting poor correlation. In contrast, squared coherence between HR time series derived from the two devices was excellent [High Frequency (HF) = 0.80, Low Frequency (LF) = 0.81], with gain values close to 1.0. ICC values for time- and frequency-domain HRV parameters were excellent (>0.9 except for relative HF HRV, which was 0.77), while ICC values for frequency-domain BP variability parameters and baroreceptor-HR reflex sensitivity were low. CONCLUSIONS: Finger volume pulse waveforms can be used to reliably assess both time-domain and frequency-domain HR variability. However, frequency domain BP variability parameters cannot be reliably assessed from finger volume pulse waveforms using the simple calibration technique used in this study.

Assessment of intrathoracic impedance algorithm in the pediatric and adult congenital population.

BACKGROUND: Decreased intrathoracic impedance has been used in adults to predict heart failure (HF) exacerbations. A commercial algorithm, OptiVol® (Medtronic Inc., Minneapolis, MN, USA), identifies patients with decreased impedance. We sought to determine the specificity, sensitivity, and positive predictive value (PPV) of OptiVol for predicting HF exacerbation or increased arrhythmia burden in pediatric and adult congenital heart disease (CHD) patients. METHODS: A multicenter retrospective chart review was undertaken. Inclusion criteria were: (1) <19 years or CHD adults, (2) an implanted device with OptiVol capability, (3) implanted between April 9 and September 6, and (4) follow-up of >30 days postimplant. Clinical events were defined as clinical HF exacerbation/hospital admission, initiation/uptitration of medication, or increased arrhythmia burden. RESULTS: Seventy-two patients (19 ± 9 years) were identified with the following indications: 20% dilated cardiomyopathy (DCM), 11% hypertrophic cardiomyopathy (HCM), 43% CHD, 15% channelopathy, and 11% other. Thirty-nine had 122 OptiVol crossings (median 2, range 1-11); 30% were linked to a cause. The remaining 33 had no crossing, though 17 had 89 clinical events. The clinical event rate was 19% greater in patients with crossings, though not statistically significant (P = 0.4). The algorithm had a 59% sensitivity, 52% specificity, and 62% PPV. Clinical HF exacerbation and arrhythmia burden did not significantly correlate with decreased impedance though uptitration or initiation of HF medication did correlate significantly (P = 0.03). CONCLUSION: The algorithm sensitivity for pediatric DCM, HCM, CHD, and adult CHD was equivalent to the general adult population. Further studies are warranted to assess whether inaccuracy in prediction is secondary to the algorithm or to differences in the clinical response of pediatric/CHD patients.

Voltage mapping for slow-pathway visualization and ablation of atrioventricular nodal reentry tachycardia in pediatric and young adult patients.

Voltage guidance for the ablation of the slow pathway in atrioventricular nodal reentry tachycardia (AVNRT) is a dramatic shift from the traditional anatomy-guided approach within the triangle of Koch. The use of voltage gradient mapping has been evaluated in adults as an aid to identification of the slow pathway guiding placement of ablation applications. This study aimed to evaluate this technique of voltage-guided ablation of AVNRT in pediatric and young adult patients, who have a smaller, more compact triangle of Koch. A retrospective cohort study evaluated patients 20 years of age or younger with AVNRT who underwent voltage mapping. Using NavX, three-dimensional voltage maps of the right atrium were created during sinus rhythm, focusing primarily on the triangle of Koch. The voltage map gradients were adjusted to uncover a "voltage bridge" of lower voltage signals. This bridge was used as a surrogate of the slow pathway to guide cryoablation at this site. Of the 31 patients who underwent voltage mapping, three were excluded from the study due to inadequate mapping. All the patients experienced procedural success. In 86 % of the patients, there was an adequate voltage bridge to allow guided ablation. The successful ablation site was within the first three lesions for 60 % of the patients. Two patients experienced recurrence during a median follow-up period of 14 months. It appears that voltage-guided ablation of a voltage bridge in AVNRT can be used effectively and safely in the pediatric population.

High-density "APLE" Mapping-Activation, Propagation, Low Voltage, and Electrogram Evaluation with the HD Grid for Atrioventricular Nodal Re-entry Tachycardia Ablation.

This is the first case series to evaluate high-density mapping of the triangle of Koch (TOK) using the HD Grid to guide slow-pathway ablation integrating activation, propagation (with wave collision), low-voltage signals, and atrial electrogram appearance. We will describe our technique and the results in this case series. Using three-dimensional mapping and the HD Grid, patients underwent high-density voltage mapping of the TOK. Ablation site selection was based on properties during sinus rhythm with late activation, at or above the propagation wave collision, over low voltage, and with appropriate electrogram appearance. Five patients underwent mapping of the slow pathway using the HD Grid. Their median age was 14 years, their median weight was 54.1 kg, and their median height was 161.5 cm. The TOK was mapped with the HD Grid for a median of 3 min. The procedure was successful in all patients using this technique. The median lesion number to the site of success was 3, with a median total number of cryotherapy lesions of 11. No radiation was used. There were no recurrences. Using activation, propagation wave, low voltage, and electrogram appearance when mapping for slow-pathway localization and ablation with the HD Grid can be successful, results in high-density maps, and is relatively faster.

Epicardial Implantation of a Micra™ Pacemaker in a Premature Neonate with Congenital Complete Heart Block.

Pacemaker implantation in neonates can be challenging due to their small size. Even pulse generators adapted for pediatric patients, such as the Microny device (Abbott, Chicago, IL, USA), are proportionately large in comparison to the size of the smallest newborns. Due to anatomic considerations, such as small vascular and ventricular sizes, leadless pacemakers and transvenous implantation in the youngest neonatal population remain unsuitable. Even so, the desire for leadless devices has prompted the industry to create the smallest pacemakers available. Adapting the smaller Micra™ transcatheter leadless pacing system (Medtronic, Minneapolis, MN, USA) for an epicardial pacing application may be advantageous to the smallest patients. This case illustrates the use of a Micra™ device modified with a header block to serve as the pulse generator in a ventricular epicardial pacing system for a 1-day-old, 2.68-kg patient with complete heart block.

Implanted defibrillators in young hypertrophic cardiomyopathy patients: a multicenter study.

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease, with an annual risk of sudden cardiac death (SCD) estimated at 1 %. Limited data are available regarding both the risk of SCD in the young HCM population and the use of implantable cardioverter-defibrillators (ICDs). This retrospective study included all patients with HCM who underwent ICD implantation for primary or secondary prevention of SCD before the age of 30 years at five institutions between 1995 and 2009. There were 99 devices implanted in 73 patients. Appropriate shocks occurred for 11 % of all the patients. None of the previously identified conventional risk factors for SCD in HCM patients were associated with increased risk of appropriate shocks in the young study cohort. During a median follow-up period of 2.4 years, inappropriate shocks occurred for 22 % of the patients. Older age at implant was associated with a decreased risk of inappropriate shock. Those who underwent implantation in the earlier decade had a higher incidence of inappropriate shocks. Late complications including lead fracture or dislodgement, generator malfunction, and infection occurred for 32 % of the patients. Three patients died (4 %), one of whom had an arrhythmic sudden death. A greater proportion of primary prevention implantations was performed for patients from the latter decade. Over time, ICD use in young HCM patients has become increasingly primary prevention oriented. Shock rates mirror those reported in adult series, and there is a substantial incidence of device complications.

Cryoablation therapy for atrioventricular nodal reentrant tachycardia in children: a multicenter experience of efficacy.

Atrioventricular nodal reentrant tachycardia (AVNRT), a common tachycardia in children, is routinely treated by catheter ablation using radiofrequency or cryothermal energy. Acute success rates of 95-97 % are reported for cryoablation, similar to those achieved with radiofrequency ablation (RFA). However, early studies reported higher recurrence rates after cryoablation for treatment of AVNRT than those reported for RFA. This study evaluated the success and recurrence rates for cryoablation in a current cohort of pediatric patients across several institutions. Patients 21 years old or younger with AVNRT who underwent cryoablation at five participating centers between 2004 and 2009 were retrospectively reviewed. Patient demographics and procedural data were extracted from patient records and analyzed. A total of 434 patients with AVNRT who underwent cryoablation were identified. Cryoablation was used as the exclusive ablation method for 379 patients. For 97 % (368/379) of these patients, cryoablation was acutely successful. A higher acute success rate was found with the 6-mm-tip catheter (99 %) than with the 4-mm-tip catheter (91 %) (p < 0.01). Recurrence was experienced by 7.3 % of the patients. Recurrence was more likely for those treated with the 4-mm-tip catheter (6/42, 14 %) than for those who had the larger catheters (12/204, 6 %) No patient experienced permanent heart block. Success and recurrence rates for this cohort of patients were similar to those reported for RFA used to treat AVNRT in pediatric patients. The findings show a higher success rate and a lower recurrence rate after cryoablation with a 6-mm-tip catheter than after use of the 4-mm-tip catheter, with an associated excellent safety profile.

IV Sotalol Use in Pediatric and Congenital Heart Patients: A Multicenter Registry Study.

Background There is limited information regarding the clinical use and effectiveness of IV sotalol in pediatric patients and patients with congenital heart disease, including those with severe myocardial dysfunction. A multicenter registry study was designed to evaluate the safety, efficacy, and dosing of IV sotalol. Methods and Results A total of 85 patients (age 1 day-36 years) received IV sotalol, of whom 45 (53%) had additional congenital cardiac diagnoses and 4 (5%) were greater than 18 years of age. In 79 patients (93%), IV sotalol was used to treat supraventricular tachycardia and 4 (5%) received it to treat ventricular arrhythmias. Severely decreased cardiac function by echocardiography was seen before IV sotalol in 7 (9%). The average dose was 1 mg/kg (range 0.5-1.8 mg/kg/dose) over a median of 60 minutes (range 30-300 minutes). Successful arrhythmia termination occurred in 31 patients (49%, 95% CI [37%-62%]) with improvement in rhythm control defined as rate reduction permitting overdrive pacing in an additional 18 patients (30%, 95% CI [19%-41%]). Eleven patients (16%) had significant QTc prolongation to >465 milliseconds after the infusion, with 3 (4%) to >500 milliseconds. There were 2 patients (2%) for whom the infusion was terminated early. Conclusions IV sotalol was safe and effective for termination or improvement of tachyarrhythmias in 79% of pediatric patients and patients with congenital heart disease, including those with severely depressed cardiac function. The most common dose, for both acute and maintenance dosing, was 1 mg/kg over ~60 minutes with rare serious complications.

Nonfluoroscopic and radiation-limited ablation of ventricular arrhythmias in children and young adults: a case series.

The purpose of this study was to report the feasibility and procedural technique of minimal or no fluoroscopy in the ablation of ventricular arrhythmias in the pediatric population. A retrospective review was performed of all patients <21 years old who underwent ablation of ventricular arrhythmias using three-dimensional (3D) mapping with no or minimal fluoroscopy at a single institution. Five patients underwent electrophysiology studies for ventricular tachycardia or frequent premature ventricular complexes. Three patients had right-sided arrhythmias, and two patients had left-sided arrhythmias. Electro-anatomic mapping with the 3D EnSite NavX system and radiofrequency ablation was used in all patients. No fluoroscopy was used in the patients with right-sided arrhythmias. The two patients with left-sided arrhythmias had 1.0 and 1.9 min of fluoroscopy, respectively. The mean procedure time was 168 min (range 95 to 270). There has been no recurrence at mean follow-up of >1 year. Three-dimensional mapping systems have allowed pediatric electrophysiologic procedures to be performed with minimal to no fluoroscopy in patients with challenging arrhythmias, including ventricular arrhythmias. The decrease in radiation exposure decreases the risk of long-term adverse sequelae resulting from radiation exposure, which is especially important in children.

Multicenter study of the effectiveness of implantable cardioverter defibrillators in children and young adults with heart disease.

Implantable cardioverter defibrillators (ICDs) are being used with increasing frequency in children and young adults. Our aim was to examine the appropriateness and frequency of ICD discharges in children and young adults, to compare the effectiveness of ICDs when placed for primary or secondary prevention, and to provide time-dependent analysis of ICD discharges. Data were collected from seven institutions on 210 patients <30 years of age who underwent ICD implantation from October 1992 to January 2007. Median age at implant was 15.4 years with a follow-up average of 3.3 years. Heart disease was categorized as electrical (n = 90, 42%), cardiomyopathic (n = 62, 30%), or congenital heart disease (n = 58, 28%). ICDs are increasingly placed for primary prevention. There are increased appropriate ICD discharges for ICDs placed for secondary prevention (52%) versus primary prevention (14%) at 5 years. There is no difference in the risk of inappropriate discharges between primary and secondary prevention indications. There is an increased risk for inappropriate therapy in the congenital heart disease population. An increasing number of ICDs are being placed for primary prevention in young patients, a marked shift in practice during the last two decades. The benefits of ICDs remain greater in secondary than in primary-prevention patients. In both groups, approximately 25% of patients received inappropriate discharges within 5 years of implant. Patients with congenital heart disease are the most affected by inappropriate discharges.

Atrial Electrography for Postoperative Tachyarrhythmia Analysis in Patients.

The over 400,000 cardiac surgeries performed in the United States each year hold a risk for the postoperative complication of arrhythmias. Currently, bedside monitoring of surface electrocardiogram leads is used to interpret arrhythmias despite the evidence that atrial electrograms (AEGs) offer superior rhythm discrimination. This hesitancy to use the AEG may be due to a lack of training for practitioners in interpreting AEGs; therefore, our goal was to create an algorithm for the diagnosis of tachyarrhythmia using an AEG that can be utilized by any health care practitioner. Our algorithm classifies the most prevalent type of tachyarrhythmias following cardiac surgery. To allow rhythm identification, we categorized them based on their atrial to ventricular signal ratio, which is uniquely apparent on AEGs. Other considerations were given to rhythm regularity, consistency, P-wave axis, and rate. The algorithm includes the most common postoperative arrhythmias differentiated based on a unique branch-point approach, which walks through the steps in arrhythmia discrimination. Both rendered and collected AEGs are included as references for further understanding and interpretation of tachyarrhythmias. The utility of AEGs for rhythm discrimination post-cardiac surgery is established and recent technology can provide real-time and continuous monitoring; however, practitioner training may be inadequate. To bridge this divide, we created an algorithm so that existing atrial wires can be better used for an enhanced rhythm interpretation via AEGs.

Outcomes of Pediatric Patients With Defibrillators Following Initial Presentation With Sudden Cardiac Arrest.

BACKGROUND: Implantable cardioverter defibrillators (ICD) are recommended for secondary prevention after sudden cardiac arrest (SCA). The outcomes of pediatric patients receiving an ICD after SCA remain unclear. The objective of this study is to evaluate outcomes, future risk for appropriate shocks, and identify characteristics associated with appropriate ICD therapy during follow-up. METHODS: Multicenter retrospective analysis of patients (age ≤21 years) without prior cardiac disease who received an ICD following SCA. Patient/device characteristics, cardiac function, and underlying diagnoses were collected, along with SCA event characteristics. Patient outcomes including complications and device therapies were analyzed. RESULTS: In total, 106 patients were included, median age 14.7 years. Twenty (19%) received appropriate shocks and 16 (15%) received inappropriate shocks (median follow-up 3 years). First-degree relative with SCA was associated with appropriate shocks (P<0.05). In total, 40% patients were considered idiopathic. Channelopathy was the most frequent late diagnosis not made at time of presentation. Neither underlying diagnosis nor idiopathic status was associated with increased incidence of appropriate shock. Monomorphic ventricular tachycardia (hazard ratio, 4.6 [1.2-17.3]) and family history of sudden death (hazard ratio, 6.5 [1.4-29.8]) were associated with freedom from appropriate shock in a multivariable model (area under the receiver operating characteristic curve, 0.8). Time from diagnoses to evaluation demonstrated a nonlinear association with freedom from appropriate shock (P=0.015). In patients >2 years from implantation, younger age (P=0.02) and positive exercise test (P=0.04) were associated with appropriate shock. CONCLUSIONS: The risk of future device therapy is high in pediatric patients receiving an ICD after SCA, irrelevant of underlying disease. Lack of a definitive diagnosis after SCA was not associated with lower risk of subsequent events and does not obviate the need for secondary prophylaxis.