Incidence and outcome of arrhythmias and electrical disease in patients with Trisomy 18

Patients with Trisomy 18 have a high incidence of cardiac anomalies and are associated with early death. Because of early mortality, electrical system disease and arrhythmia has been difficult to delineate and the incidence remain unknown. We sought to describe the association and clinical outcomes of electrical system disease and cardiac tachy-arrhythmias in patients with Trisomy 18. This was a retrospective, single institutional study. All patients with Trisomy 18 were included in the study. Patient characteristics, congenital heart disease (CHD), conduction system and clinical tachy-arrhythmia data were collected on all patients. Outcomes including cardiac surgical interventions, electrical system interventions and death were collected until the time of study. Patients with tachy-arrhythmias/electrical system involvement were compared to those without to identify potential associated variables. A total of 54 patients with Trisomy 18 were included in analysis. The majority of patients was female and had associated CHD. AV nodal conduction system abnormalities with either first or second degree AV block were common (15%) as was QTc prolongation (37%). Tachy-arrhythmias were common with 22% of patients having at least one form of tachy-arrhythmia and associated with concomitant conduction system disease (p = 0.002). Tachy-arrhythmias were typically treatable with monitoring or medication with eventual resolution without need for procedural intervention. Although early death was common, there were no causes of death associated with tachy-arrhythmia or conduction system disease. In conclusion, patients with Trisomy 18 have a high incidence of conduction system abnormalities and burden of clinical tachy-arrhythmias. Although frequent, electrical system disease did not affect patient outcome or difficultly of care delivery.

Transesophageal pacing studies reduce readmission but prolong initial admission in infants with supraventricular tachycardia: A cost-comparison analysis

Background

Supraventricular tachycardia (SVT) is a common arrhythmia. Infants with SVT are often admitted to initiate antiarrhythmics. Transesophageal pacing (TEP) studies can be used to guide therapy prior to discharge.

Objective

The objective of this study was to investigate the impact of TEP studies on length of stay (LOS), readmission, and cost in infants with SVT.

Methods

This was a 2-site retrospective review of infants with SVT. One site (Center TEPS) utilized TEP studies in all patients. The other (Center NOTEP) did not. Patients with structural heart disease, patients with gestational age <34 weeks, and patients diagnosed after 6 months were excluded. At Center TEPS, repeat TEP studies were performed after titration of medication until SVT was not inducible. Primary endpoints were LOS and readmission for breakthrough SVT within 31 days of discharge. Hospital reimbursement data were utilized for cost-effectiveness analysis.

Results

The cohort included 131 patients, 59 in Center TEPS and 72 in Center NOTEP. One patient was readmitted in Center TEPS vs 17 in Center NOTEP (1.6% vs 23.6%; P ≤ .001). Median LOS was longer for Center TEPS at 118.0 (interquartile range [IQR] 74.0-189.5) hours vs Center NOTEP at 66.9 (IQR 45.5-118.3) hours (P = .001). Twenty-one patients had multiple TEP studies. Median length of readmission for Center NOTEP was 65 (IQR 41-101) hours. Including readmission costs, utilization of TEP studies resulted in a probability-weighted cost of $45,531 per patient compared with $31,087 per patient without TEP studies.

Conclusion

Utilization of TEP studies was associated with decreased readmission rates but longer LOS and greater cost compared with SVT management without TEP studies.

Outcomes in Infants with Supraventricular Tachycardia: Risk Factors for Readmission, Recurrence and Ablation

Supraventricular tachycardia (SVT) is the most common arrhythmia in infants. Once diagnosed, infants are admitted for antiarrhythmic therapy and discharged after observation. There are limited data on risk factors for readmission and readmission rates, while on medication. The objective of this study was to investigate risk factors for readmission and outcomes in infants diagnosed with SVT. This is a single-center retrospective study over a 10-year period of infants under 6 months of age with documented SVT. Infants with congenital heart disease requiring surgical or catheter intervention, gestational age less than 32 weeks or diagnosis of atrial flutter or fibrillation were excluded. The primary outcome was readmission within 31 days of hospital discharge. Long term need for ablation and eventual discontinuation of medications were assessed. Ninety patients were included. Beta blockers were the initial therapy in 66 and 28 required a medication change. Nineteen were readmitted within 31 days of discharge. The only clinical factor associated with early readmission was presence of ventricular pre-excitation (6/19 vs. 8/71, p = 0.03). Patients who were readmitted within 31 days had a longer length of treatment (12 [11.5, 22.0] vs. 10 [7.5, 12.0] months, p = 0.007) and were more likely to undergo ablation (4/19 vs. 2/71, p = 0.017). In this cohort of infants with SVT, readmission was common and ventricular pre-excitation was identified as a risk factor for readmission. Infants who were readmitted within 31 days of discharge had longer length of antiarrhythmic therapy and were more likely to undergo catheter ablation.

Continuous Arrhythmia Monitoring in Pediatric and Adult Patients With Left Ventricular Noncompaction

Patients with left ventricular noncompaction (LVNC) are at risk of clinically significant arrhythmias and sudden death. We evaluated whether implantable loop recorders could detect significant arrhythmias that might be missed in these patients during annual Holter monitoring. Selected pediatric and adult patients with LVNC who consented to implantable loop recorder placement were monitored for 3 years (study duration, 10 April 2014-9 December 2019). Fourteen subjects were included (age range, 6.5-36.4 yr; 8 males). Of 13 patients who remained after one device extrusion, one underwent implantable cardioverter-defibrillator placement. Four patients (31%) had significant arrhythmias: atrial tachycardia (n=2), nonsustained ventricular tachycardia (n=1), and atrial fibrillation (n=1). All 4 events were clinically asymptomatic and not associated with left ventricular ejection fraction. In addition, a high frequency of benign arrhythmic patterns was detected. Implantable loop recorders enable continuous, long-term detection of important subclinical arrhythmias in selected patients who have LVNC. These devices may prove to be most valuable in patients who have LVNC and moderate or greater ventricular dysfunction.

Outcomes of Implantable Loop Monitoring in Patients <21 Years of Age

Rhythm-symptom correlation in pediatric patients with syncope/palpitations or at risk cohorts can be difficult, but important given potential associations with treatable or malignant arrhythmia. We sought to evaluate the use, efficacy and outcomes of implantable loop recorders (ILR) in pediatrics. We conducted a retrospective study of pediatric patients (<21 years) with implanted ILR. Patient/historical characteristics and ILR indication were obtained. Outcomes including symptom documentation, arrhythmia detection and ILR based changes in medical care were identified. Comparison of outcomes were performed based on implant indication. Additional sub-analyses were performed in syncope-indication patients comparing those with and without changes in clinical management. A total of 116 patients with ILR implant were identified (79 syncope/37 other). Symptoms were documented 58% of patients (syncope 68% vs nonsyncope 35%; p = 0.002). A total of 37% of patients had a documented clinically significant arrhythmia and 25% of patients had a resultant change in clinical management independent of implant indication. Arrhythmia type was dependent on implant indication with nonsyncope patients having more ventricular arrhythmias. Pacemaker/defibrillator implantation and mediation management were the majority of the clinical changes. In conclusion, IRL utilization in selected pediatric populations is associated with high efficacy and supports clinical management. ILR efficacy is similar regardless of indication although patients with nonsyncope indications had a higher frequency of ventricular arrhythmias as opposed to asystole and heart block in syncope indications. The majority of arrhythmic findings occurred in the first 12 months, and new technology that would allow for less invasive monitoring for 6 to 12 months may be of value.

Predictors and outcomes of heart block during surgical stage I palliation of patients with a single ventricle: A report from the NPC-QIC

BACKGROUND

Mortality in cohorts with a single ventricle remains high with multiple associated factors. The effect of heart block during stage I palliation remains unclear.

OBJECTIVE

The purpose of this study was to study patient and surgical risks of heart block and its effect on 12-month transplant-free survival in patients with a single ventricle.

METHODS

Patient, surgical, outcome data and heart block status (transient and permanent) were obtained from the National Pediatric Cardiology Quality Improvement Collaborative single ventricle database. Bivariate analysis was performed comparing patients with and without heart block, and multivariate modeling was used to identify variables associated with block. One-year outcomes were analyzed to identify variables associated with lower 12-month transplant-free survival.

RESULTS

In total, 1423 patients were identified, of whom 28 (2%) developed heart block (second degree or complete) during their surgical admission. Associated risk factors for block included heterotaxy syndrome (odds ratio [OR] 6.4) and atrial flutter/fibrillation (OR 3.8). Patients with heart block had lower 12-month survival, though only in patients with complete heart block as opposed to second degree block. At 12 months of age, 43% (12/28) of patients with heart block died and were more likely to experience mortality at 12 months than patients without block (OR 4.9; 95% confidence interval 1.4-17.5; P = .01).

CONCLUSION

Although rare, complete heart block after stage I palliation represents an additional risk of poor outcomes in this high-risk patient population. Heterotaxy syndrome was the most significant risk factor for the development of heart block after stage I palliation. The role of transient block in outcomes and potential rescue with long-term pacing remains unknown and requires additional study.

Multicenter Outcomes of Catheter Ablation for Atrioventricular Reciprocating Tachycardia Mediated by Twin Atrioventricular Nodes

OBJECTIVES

This study sought to describe the electrophysiologic properties and catheter ablation outcomes for T-AVRT.

BACKGROUND

Although catheter ablation for atrioventricular (AV) reciprocating tachycardia via twin AV nodes (T-AVRT) is an established entity, there are few data on the electrophysiological properties and outcomes of this procedure.

METHODS

An international, multicenter study was conducted to collect retrospective procedural and outcomes data for catheter ablation of T-AVRT.

RESULTS

Fifty-nine patients with T-AVRT were identified (median age at procedure, 8 years [interquartile range, 4.4-17.0 years]; 49% male). Of these, 55 (93%) were diagnosed with heterotaxy syndrome (right atrial isomerism in 39, left atrial isomerism in 8, and indeterminate in 8). Twenty-three (39%) had undergone Fontan operation (12 extracardiac, 11 lateral tunnel). After the Fontan operation, atrial access was conduit or baffle puncture in 15 (65%), fenestration in 5 (22%), and retrograde in 3 (13%). Acute success was achieved in 43 (91%) of 47 attempts (targeting an anterior node in 23 and posterior node in 24). There was no high-grade AV block or change in QRS duration. Over a median of 3.8 years, there were 3 recurrences. Of 7 patients with failed index procedure or recurrent T-AVRT, 6 (86%) were associated with anatomical hurdles such as prior Fontan or catheter course through an interrupted inferior vena cava-to-azygous vein continuation (P = 0.11).

CONCLUSIONS

T-AVRT can be targeted successfully with low risk for recurrence. Complications were rare in this population. Anatomical challenges were common among patients with reduced short and long-term efficacy, representing opportunities for improvement in procedural timing and planning.

Progressive QRS Duration and Ventricular Dysfunction in Pediatric Patients with Chronic Ventricular Pacing

Pacemakers are a mainstay of therapy for patients with congenital and acquired heart block, but ventricular pacing is related to ventricular dysfunction. We sought to evaluate patient and device characteristics associated with ventricular dysfunction in pediatric patients with chronic ventricular pacing. This was a retrospective cohort of pediatric patients with heart block and chronic ventricular pacing. Patient, ECG, and device characteristics were analyzed to determine factors associated with ventricular dysfunction. Longitudinal ECG and echocardiogram parameters were obtained to track changes in QRS and systemic ventricular systolic function over time. In total, 82 patients were included (median age at implant 0.81 years). Over a follow-up time of 6.1 years, 18% developed ventricular dysfunction. Patients with dysfunction had greater current QRS duration (p = 0.002) compared to those with preserved function with a similar time from device implantation. There was no difference between lead location or age at device implantation. QRS duration increased with time from implant and the resultant ΔQRS was associated with ventricular dysfunction (p = 0.01). QRS duration >162 ms was associated with a 5.8 (2-9)-fold increased risk for dysfunction. Transvenous leads were associated with longer QRS duration with no difference compared to epicardial leads in development of ventricular dysfunction. This study demonstrated that the absolute paced QRS duration and Δpaced QRS were association with long-term ventricular dysfunction independent of how long a given patient was paced. Patients in high-risk categories may benefit from close echocardiographic monitoring. Whether permissive junctional rhythm or His bundle/biventricular pacing decreases the rate of dysfunction needs further study.

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.

Characteristics and Outcomes of Pediatric Patients Who Undergo Placement of Implantable Cardioverter Defibrillators: Insights From the National Cardiovascular Data Registry

Background Implantable cardioverter defibrillators (ICDs) are an important part of therapy for many patients, yet there is little data on population characteristics, complications, or system survival in pediatric patients. Methods A retrospective review of ICD recipients in the National Cardiovascular Data Registry ICD Registry was performed from 2010 to 2016. Patient characteristics and complications between pediatric (≤21 years) and adult populations (>21 years) were compared. Variables associated with complications and early device interventions within the pediatric cohort were evaluated using multivariate modeling. Results There were 562 209 total ICD implants, of which 3461 occurred in the pediatric cohort. Among the pediatric patients, 60% of implants were for primary prevention, and nonischemic cardiomyopathy was the most common underlying disease (60%). Over time, there was an increasing trend of both primary and secondary prevention ICD implantations ( P<0.05). Compared with adults, pediatric patients were more likely to have structural heart disease, hypertrophic cardiomyopathy, and channelopathy, and to receive a single-chamber device (all P<0.001). There was no difference in inhospital complications between the adult and pediatric cohorts (2.4% versus 2.6%, P=0.3). However, among the pediatric patients, lower weight, Ebstein anomaly, worse New York Heart Association class, dual chamber, and cardiac resynchronization therapy-defibrillator were associated with greater risk of complications. Although reintervention for generator replacement or upgrade was more common in adults, the time to reintervention was shorter in the pediatric cohort. Conclusions We observed an increasing trend in ICD device implantation among pediatric patients. The pediatric cohort had similar inhospital complication rates compared with adults but had a shorter time to reintervention.

Wearable cardioverter-defibrillators in pediatric cardiomyopathy: A cost-utility analysis

BACKGROUND

Dilated cardiomyopathy (DCM) is the most common cardiomyopathy in children. Patients with severe cardiac dysfunction are thought to be at risk of sudden cardiac arrest (SCA). After diagnosis, a period of medical optimization is recommended before permanent implantable cardioverter-defibrillator (ICD) implantation. Wearable cardioverter-defibrillators (WCDs) provide an option for arrhythmia protection as an outpatient during this optimization.

OBJECTIVE

The purpose of this study was to determine the strategy that optimizes cost and survival during medical optimization of a patient with DCM before ICD placement.

METHODS

A Markov state transition model was constructed for the 3 clinical approaches to compare costs, clinical outcomes, and quality of life: (1) "Inpatient," (2) "Home-WCD," and (3) "Home-No WCD." Transitional probabilities, costs, and utility metrics were extracted from the existing literature. Cost-effectiveness was assessed comparing each paradigm's incremental cost-effectiveness ratio against a societal willingness-to-pay threshold of $50,000 per quality-adjusted life year.

RESULTS

The cost-utility analysis illustrated that Home-WCD met the willingness-to-pay threshold with an incremental cost-effectiveness ratio of $20,103 per quality-adjusted life year and 4 mortalities prevented per 100 patients as compared with Home-No WCD. One-way sensitivity analyses demonstrated that Home-No WCD became the most cost-effective solution when the probability of SCA fell below 0.2% per week, the probability of SCA survival with a WCD fell below 9.8%, or the probability of SCA survival with Home-No WCD quadrupled from base-case assumptions.

CONCLUSION

Based on the existing literature probabilities of SCA in pediatric patients with DCM undergoing medical optimization before ICD implantation, sending a patient home with a WCD may be a cost-effective strategy.

Can noninvasive testing identify benign patterns of suggested pre-excitation on electrocardiogram?

BACKGROUND

The presence of anterograde conduction through an accessory pathway (AP) has been linked to sudden cardiac death. Unfortunately, pre-excitation associated with classic pathways can be difficult to differentiate from benign APs such as nodofascicular fibers.

OBJECTIVE

Identifying characteristics on electrocardiogram (ECG) and exercise that differentiate classic and benign AP connections in suggested pre-excitation patterns.

METHODS

Retrospective review of patients presenting between 1995 and 2017 with ventricular pre-excitation on ECG, determined to have either typical left-lateral AP during electrophysiology study (EPS), or benign, or no AP determined by either transesophageal electrophysiology study (TEP), or EPS.

RESULTS

A total of 96 patients were included, 14.2 years (4-24), 45% female, 90% Caucasian. Of these, 60 (63%) had a classic APs identified on EPS and 58 (97%) underwent successful ablation. Conversely, 36 (37%) had benign pathways identified. ECG findings differed between the groups: PR-interval 102 versus 120 ms (P < .0001), QRS-duration 110 versus 102 ms (P < .0001), QRS-axis 74 versus 59 degrees (P = .0005), and QRS onset to peak R/S in limb leads 64 versus 42 ms (P < .0001), and precordial leads 66 versus 46 ms (P < .0001). Change in QRS duration during exercise differed between the groups: 25 versus 2 ms (P < .0001) and ECG characteristics identified the presence of an AP with 97% sensitivity and 94% negative predictive value.

CONCLUSION

Classic and benign APs exhibit different ECG characteristics, though clinical overlap does not allow for absolute differentiation. These data may help with risk stratification decision making though does not obviate the need for additional invasive testing.

Ventricular force-frequency relationships during biventricular or multisite pacing in congenital heart disease

BACKGROUND

Traditional indices to evaluate biventricular (BiV) pacing are load dependent, fail to assess dynamic changes, and may not be appropriate in patients with congenital heart disease (CHD). We therefore measured the force-frequency relationship (FFR) using tissue Doppler-derived isovolumic acceleration (IVA) to assess the dynamic adaption of the myocardium and its variability with different ventricular pacing strategies.

METHODS

This was a prospective pilot study of pediatric and young adult CHD patients with biventricular or multisite pacing systems. Color-coded myocardial velocities were recorded at the base of the systemic ventricular free wall. IVA was calculated at resting heart rate and with incremental pacing. FFR curves were obtained by plotting IVA against heart rate for different ventricular pacing strategies.

RESULTS

Ten patients were included (mean: 22 ± 7 years). The FFR identified a best and worst ventricular pacing strategy for each patient, based on the AUC at baseline, submaximal, and peak heart rates (P < .001). However, there was no single best ventricular pacing strategy that was optimal for all patients. Additionally, the best ventricular pacing strategy often differed within the same patient at different heart rates.

CONCLUSION

This novel assessment demonstrates a wide variability in optimal ventricular pacing strategy. These inherent differences may play a role in the unpredictable clinical response to BiV pacing in CHD, and emphasizes an individualized approach. Furthermore, the optimal ventricular pacing varies with heart rate within individuals, suggesting that rate-responsive ventricular pacing modulation may be required to optimize ventricular performance.

Patient understanding of disease and the use and outcome of implantable cardioverter defibrillators in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death (SCD) in young individuals. Implantable cardioverter defibrillators (ICD) are the primary therapy for sudden death prevention; however, are associated with both physical and psychological complications. We sought to determine factors associated with ICD understanding and patient satisfaction. This was a cross-sectional study, using patient/parent answered questionnaires distributed to patients enrolled in the Hypertrophic Cardiomyopathy Association. Patient characteristics and satisfaction data were obtained via questionnaire. Patients were compared based on age at diagnosis and presence of ICD. ICD patients with high satisfaction were compared to those with low satisfaction to determine factors associated with poor satisfaction. A total of 538 responses were obtained (53 ± 16 years); 46% were females. Seventy patients (13%) were diagnosed with HCM < 18 years of age and 356 (66%) had an ICD. Compared to those without an ICD, patients with ICDs were younger at age of diagnosis (P = 0.001) and time of study (P = 0.008). Patients with ICDs were more likely to have presented with syncope and have family history of ICD, SCD, or HCM-related death. Nineteen patients (5%) felt that issues surrounding their ICD outweighed its benefit. Compared to patients with a favorable satisfaction, the only significant difference was the preimplant ICD discussion (P < 0.001) and history of lead replacement (P = 0.01). In conclusion, the majority of HCM patients with ICDs are satisfied with their ICD management and feel the benefits of ICDs outweigh issues associated with ICDs. Additionally, these data highlight the importance of the preimplant patient-physician discussion around the need for ICD prior to implantation.

Wearable cardioverter defibrillators in schools: A guide for parents and educators

Keeping children safe is a goal for everyone. To stay safe, some children need a wearable cardioverter defibrillator (WCD). WCDs protect individuals who are at risk for life-threatening arrhythmias. The LifeVest^® (ZOLL, Pittsburgh, PA, USA) is a WCD that identifies, records, and treats potentially life-threatening abnormal heartbeats, or arrhythmias. The WCD will provide electrical energy to the heart with up to five high-energy shocks if a potentially dangerous cardiac arrhythmia is detected. This type of arrhythmia, if not treated within a short time period (less than 2 minutes), can result in disruption of blood flow to the brain and other vital organs (that is, a sudden cardiac arrest), and death can occur within minutes. A shock delivered by the LifeVest can terminate an arrhythmia and restore a normal heart rhythm and blood flow to the body. In December 2015, the Food and Drug Administration approved the LifeVest for patients under 18 years old. The purpose of this guide is to serve as a resource for parents and educators, to promote awareness of the LifeVest, and to answer questions about the safety of the LifeVest in schools.

Proper Electronic Order Linkage of Electrocardiograms at a Large Children's Hospital Improves Reporting and Revenue

Electrocardiograms (ECGs) are performed to determine an individual's cardiac rhythm. Approximately 25,000 ECGs are performed yearly throughout our hospital system. Historically only 68% of all ECGs were performed with the proper order linked to the electronic ECG reading system (MUSE). Failure to link the orders to the electronic reading system leads to problems in patient safety, reporting and hospital revenue.

Our aim was to increase the percentage of linked ECG orders in MUSE compared to total ECGs performed from 68% to 95%.

We created a detailed process map of ECG order linking to the MUSE electronic system. FMEA and Pareto chart creation were used to determine etiology of process failures. Multiple interventions (LOR1 to LOR3) were implemented utilizing the PDSA technique. Process control charts were used to evaluate change.

FMEA and Pareto chart determined most common failures were related to: 1) ECG order not electronically acquired properly, 2) duplicate ECGs and 3) ECG order was not electronically placed. We performed multiple interventions including: 1) ECG performance education, 2) created reminders on the ECG machines, 3) specialized electronic linking system for physician readers and 4) bar-code scanners for all ECG machines. These changes improved ECG order linking to MUSE from 68% to 95% over 6-months. In direct comparison between fiscal year (FY) FY2014 to FY2015, the number of ECGs performed increased 2% while billing increased by 23%.

Utilization of quality improvement methodology allowed us to identify failures for ECG order linking. We established multiple successful interventions amongst different hospital locations and improved our compliance, billing and reporting of ECGs.

Utility and safety of the SafeSept™ transseptal guidewire for electrophysiology studies with catheter ablation in pediatric and congenital heart disease

PURPOSE

The atrial transseptal procedure is used in catheter ablation of left-sided arrhythmias. Studies in adult patients have shown the SafeSept™ transseptal guidewire (SSTG) to be effective in atrial transseptal procedures. We analyzed our 5-year experience with SSTG use in pediatric and congenital heart disease patients undergoing catheter ablation.

METHODS

This is a single-center retrospective analysis of patients undergoing catheter ablation from 2009 to 2014. We identified all procedures where SSTG was used for atrial transseptal or trans-baffle access. Success of transseptal access and complications were recorded and compared to the standard transseptal approach without the SSTG.

RESULTS

One hundred twenty-seven patients underwent 132 attempted atrial transseptal or trans-baffle procedures using SSTG. Median age was 14 (1.2-38) years. Arrhythmia substrates included AV reentrant tachycardia (90.2%), atrial tachycardia (4.5%), ventricular tachycardia (2.3%), and AV nodal reentrant tachycardia (2.3%). Transseptal or trans-baffle access was successful in 96.2% of the SSTG cases compared to 98.9% in the standard transseptal group without SSTG (p = NS). The youngest patient with successful atrial transseptal procedure using SSTG was 4 years old. SSTG was used to successfully cross a surgically created atrial baffle in a patient who had undergone the Mustard procedure. There was one major complication in both groups, 0.8% in the SSTG group compared to the standard transseptal group without SSTG, 1.1% (p = NS). The major complication in the SSTG group occurred when the SSTG crossed the aorta into the coronary artery system and mimicked placement in the left atrial appendage, with subsequent placement of a transseptal sheath into the aorta, requiring sternotomy and surgical intervention.

CONCLUSIONS

SSTG is effective for use in atrial transseptal and surgical trans-baffle access in pediatric and congenital heart disease patients. Placement of the SSTG into the pulmonary vein is necessary to avoid major complications, and if not achieved requires additional methods to determine appropriate left atrial placement.

Risk factors for complications in the implantation of epicardial pacemakers in neonates and infants

BACKGROUND

Complications related to epicardial pacemakers in infants have been reported, though limited data are available on their incidence and associated risk factors.

OBJECTIVE

The hypothesis of the study is that younger, smaller patients and larger devices would be associated with complications in neonates and infants.

METHODS

This is a retrospective study of all patients at a single center receiving an epicardial pacemaker at ≤12 months of age (1996-2015). Patient and device characteristics were obtained. Characteristics of patients with and without complications were compared.

RESULTS

There were 86 patients with a median age of 73 days (interquartile range 13-166 days), of whom 12 (14%) had a complication. Eight (9%) needed surgical intervention, of whom 5 (6%) required explantation. Younger age (9 days vs 89 days; P = .01) and lower weight (2.91 kg vs 4.44 kg; P = .004) at implantation were associated with complications. Device characteristics were not statistically different. Patients ≤3 kg in weight and/or <5 days of age had an odds ratio of 18.1 (3.6-91.2; P < .001) for developing a complication with a negative predictive value (NPV) of 97%. Regardless of weight, patients aged >21 days were found to be at lower risk with an NPV of 96%; and regardless of age, patients weighing >4 kg had an NPV of 98%.

CONCLUSION

Young age and low weight at the time of implantation are risk factors for complications, while device characteristics appear to play a minor role. Reserving pacemaker implantation for patients >3 kg in weight and 5 days of age may predict patients at low risk of developing complications.

Unexpectedly low left ventricular voltage on ECG in hypertrophic cardiomyopathy

OBJECTIVE

While late gadolinium enhancement (LGE) in paediatric patients with hypertrophic cardiomyopathy (HCM) is reported as similar to adults, the relationship between LGE and ECG findings in paediatric patients is unknown. We sought to evaluate the relationship between LGE on cardiac MRI and LV precordial voltage on ECG.

METHODS

This was a retrospective analysis of paediatric patients with HCM aged 9-21 years with cardiac MRI and ECG completed within 60 days of each other. Demographic, MRI and ECG data were compared between patients with and without LGE. Maximal diastolic septal thickness, septal to free wall ratio and LGE presence were compared with LV precordial voltage (SV1, RV6 and SV1+RV6).

RESULTS

This study included 37 patients (33 male). Mean age was 15.8±2.8 years. Mean maximal LV diastolic septal thickness was 22.1±7.9 mm. Mean septal to free wall ratio was 2.4±1.6 mm. LGE was present in 18 patients, with 16 isolated to the ventricular septum. Comparing patients with and without LGE, there was no difference in age (p=0.2) or body surface area (p=0.9). However, the presence of LGE was associated with significantly increased septal thickness (p=0.03), yet decreased voltages in SV1 (p=0.005), RV6 (p=0.005) and SV1+RV6 (p=0.002) despite increased septal dimensions.

CONCLUSIONS

A significant inverse relationship exists between LGE presence and LV precordial voltage in this population. Unexpectedly low LV precordial voltages in patients with HCM may serve as a clinical surrogate marker for myocardial fibrosis and potential loss of viable myocardial tissue.

Ambulatory Monitoring and Arrhythmic Outcomes in Pediatric and Adolescent Patients With Duchenne Muscular Dystrophy

BACKGROUND

Patients with Duchenne Muscular Dystrophy (DMD) develop cardiac fibrosis and dilated cardiomyopathy. We described the frequency of significant Holter findings in DMD, the relationship between cardiac function and arrhythmia burden, and the impact of these findings on clinical management.

METHODS AND RESULTS

A retrospective review was done of patients with DMD who received a Holter from 2010 to 2014. Clinical and arrhythmic outcomes were analyzed. Patients were classified based on left ventricular ejection fraction (LVEF): ≥55%, 35% to 54% and <35%. Significant Holter findings included atrial tachycardia, ventricular tachycardia and atrial fibrillation/flutter. Logistic regression was used to assess predictors of significant Holter findings and change in care. The study included 442 Holters in 235 patients. Mean age was 14±4 years. Patients with cardiac dysfunction were older, and had increased late gadolinium enhancement and left ventricular dilation (P<0.01). There were 3 deaths (1%), all with normal function and none cardiac. Patients with LVEF <35% had more arrhythmias including nonsustained atrial tachycardia (P=0.01), frequent premature ventricular contractions, ventricular couplets/triplets, and nonsustained ventricular tachycardia (P<0.001) compared to the other groups. LVEF <35% (P<0.001) was the only predictor of clinically significant Holter finding. Four patients (40%) had change in medication in the LVEF <35% group compared to 9 (3%) in the ≥55% and 4 (4%) in the 35% to 54% groups (P<0.001).

CONCLUSIONS

Sudden cardiac events are rare in DMD patients with an LVEF >35%. Significant Holter findings are rare in patients with DMD who have an LVEF >35%, and cardiac dysfunction appears to predict significant Holter findings. Holter monitoring is highest yield among DMD patients with cardiac dysfunction.

Short QT Interval Prevalence and Clinical Outcomes in a Pediatric Population

BACKGROUND

Risk associated with short QT interval has recently received recognition. European studies suggest a prevalence of 0.02% to 0.1% in the adult population, but similar studies in pediatric patients are limited. We sought to determine the prevalence of short QT interval in a pediatric population and associated clinical characteristics and outcomes.

METHODS AND RESULTS

Retrospective review of an ECG database at a single pediatric institution. The database was queried for ECGs on patients ≤21 years with electronically measured QTc of 140 to 340 ms. Patients with QTc of 140 to 340 ms confirmed by a pediatric electrophysiologist were identified for chart review for associated clinical characteristics, symptoms, and outcome. Patients with and without symptoms were compared in an attempt to identify variables associated with outcome. The query included 272 504 ECGs on 99 380 unique patients. Forty-five patients (35 men, 76%) had QTc ≤340 ms, for a prevalence of 0.05%. Median age was 15 years (interquartile range, 2-17), median QT 330 ms (interquartile range, 280-360), and median QTc 323 ms (IQR, 313-332). Women had significantly shorter QTc compared with men (312 versus 323 ms; P=0.03). Two deaths were noted in chart review--one from respiratory failure and the second of unknown pathogenesis in a patient with dilated cardiomyopathy.

CONCLUSIONS

Short QT interval was a rare finding in this pediatric population, with a prevalence of 0.05%. Male predominance was identified, although the median QT interval was significantly shorter in women. There seem to be no unifying clinical characteristics for this pediatric patient cohort with short QT interval.

Usefulness of ventricular premature complexes in asymptomatic patients ≤21 years as predictors of poor left ventricular function

Although ventricular premature complexes (VPCs) have been shown to correlate with decreased cardiac function in adults, the correlation of left ventricular (LV) function to VPCs in asymptomatic children remains unclear. The aim of this study was to determine the correlation of VPC burden with LV function in asymptomatic pediatric patients with structurally normal hearts. This was a retrospective analysis of patients aged ≤21 years with echocardiograms and 24-hour Holter monitors with ≥0.5% VPCs completed within 60 days of each other. LV fractional shortening (FS) was compared with VPC burden and VPC characteristics. Normal LV function was defined as FS ≥28%. Correlation between VPC burden and LV function was determined by regression analysis. Wilcoxon's rank-sum test was used to compare LV function with VPC characteristics. This study included 123 patients (77 male [63%]). The median age was 11.6 years (interquartile range 5.8 to 14.3). The median VPC burden was 11.2% (interquartile range 4.8% to 18.9%), and median FS was 36% (interquartile range 33% to 38%). There was no significant correlation between VPC burden and LV FS (p = 0.50). The presence of uniform versus multiform VPCs (p = 0.29), ventricular couplets (p = 0.37), or runs of ventricular ectopy (p = 0.19) were not associated with a decrease in LV FS. Twenty-two patients (18%) had VPC burden >24%, none of which had decreased LV FS. In conclusion, there was no significant relation between VPC burden or VPC characteristics and LV systolic function in this pediatric population with structurally normal hearts.

Cryoablation of anteroseptal accessory pathways with a his bundle electrogram on the ablation catheter

Background

Radiofrequency catheter ablations of anteroseptal (AS) accessory pathways (AP) in pediatric patients have higher incidence of atrioventricular (AV) block than other AP locations. We report our experience using cryoablation in pediatric patients where a His bundle electrogram was noted on the ablation catheter at the site of the successful ablation.

Methods and Results

We retrospectively reviewed all patients ≤21 years that underwent cryoablation for an AS AP from 2005 to 2012 at our institution (n=70). Patients with a His bundle electrogram noted on the cryoablation catheter at the location of the successful lesion were identified (n=6, 8.5%). All six patients had ventricular preexcitation. Median age of 15.9 years (7.2 - 18.2). AV nodal function was monitored during the cryoablation with intermittent rapid atrial pacing conducted through the AV node (n=2), with atrial extra-stimulus testing (n=2), or during orthodromic reentrant tachycardia (n=2). Acute success occurred in all patients. Two patients had early recurrence of AP conduction. Both patients underwent a second successful cryoablation, again with a His bundle electrogram on the cryoablation catheter. At a median follow-up of 13 months (3 to 37 months) there was no recurrence of accessory pathway conduction and AVN function was normal.

Conclusion

In a small number of pediatric patients with AS AP with a His bundle electrogram seen on the ablation catheter, the use of cryotherapy was safe and effective for elimination of AP conduction without impairment of AV nodal conduction.

Cost-effectiveness of various risk stratification methods for asymptomatic ventricular pre-excitation

Accessory pathways with "high-risk" properties confer a small but potential risk of sudden cardiac death. Pediatric guidelines advocate for either risk stratification or ablation in patients with ventricular pre-excitation but do not advocate specific methodology. We sought to compare the cost of differing risk-stratification methodologies in pediatric patients with ventricular pre-excitation in this single institutional, retrospective cohort study of asymptomatic pediatric patients who underwent risk stratification for ventricular pre-excitation. Institutional methodology consisted of stratification using graded exercise testing (GXT) followed by esophageal testing in patients without loss of pre-excitation and ultimately ablation in high-risk patients or patients who became clinically symptomatic during follow-up. A decision analysis model was used to compare this methodology with hypothetical methodologies using different components of the stratification technique and an "ablate all" method. One hundred and two pediatric patients with asymptomatic ventricular pre-excitation underwent staged risk stratification; 73% of patients were deemed low risk and avoided ablation and the remaining 27% ultimately were successfully ablated. The use of esophageal testing was associated with a 23% (p ≤0.0001) reduction in cost compared with GXT stratification alone and a 48% (p ≤0.0001) reduction compared with the "ablate all" model. GXT as a lone stratification method was also associated with a 15% cost reduction (p ≤0.0001) compared with the "ablate all" method. In conclusion, risk stratification of pediatric patients with asymptomatic ventricular pre-excitation is associated with reduced cost. These outcomes of cost-effectiveness need to be combined with the risks and benefits associated with ablation and risk stratification.

Symptomatic upper-extremity deep venous thrombosis after pacemaker placement in a pediatric patient: how to treat?

Symptomatic upper-extremity deep venous thrombosis (UEDVT) after pacemaker placement in adults has been reported, but the occurrence of UEDVT in pediatric patients is poorly defined, and no treatment guidelines exist. This report describes a 14-year old girl with a history of complete atrioventricular block who experienced a symptomatic UEDVT 8 months after placement of a transvenous pacemaker. The girl was treated initially with anticoagulation including subcutaneous enoxaparin and a heparin drip, which did not resolve the venous obstruction. In the interventional laboratory, a venogram demonstrated complete obstruction of the left subclavian vein, which was treated successfully with catheter-directed alteplase, direct thrombus removal by manual suctioning, and balloon angioplasty. Warfarin therapy was continued for an additional 6 months, with follow-up venous ultrasounds demonstrating left subclavian vein patency. Soon after completing warfarin therapy, the girl presented with minimal edema of her left distal extremity and was thought to have post-thrombotic syndrome, which resolved quickly. She continued to receive aspirin therapy, with no recurrence of symptoms. In conclusion, symptomatic UEDVT after pacemaker placement in a pediatric patient can be treated successfully with both anticoagulation and interventional therapies. Further studies are needed to evaluate the incidence of thrombus formation among children with transvenous pacemaker placement together with the development of guidelines based on the safety and effectiveness of differing treatments.

Relation of the utility of exercise testing for risk assessment in pediatric patients with ventricular preexcitation to pathway location

The gradual loss of ventricular preexcitation during exercise stress testing (EST) has an unclear risk of an association with life-threatening arrhythmia and could be related to the accessory pathway (AP) location. We compared the loss of preexcitation during EST with the risk assessment during invasive electrophysiology testing and determined whether the loss of preexcitation correlates with the AP location. We retrospectively reviewed patients aged ≤21 years with ventricular preexcitation who had undergone both EST and an electrophysiology study. The patients were divided into 3 groups: sudden loss (SL), gradual loss (GL), or no loss (NL) of preexcitation during EST. A total of 76 patients were included, with 11 (14%) in the SL group, 18 (24%) in the GL group, and 47 (62%) in the NL group. The SL group demonstrated a longer cycle length with 1-to-1 conduction by way of the AP during incremental atrial pacing compared with the NL group (375 ± 135 ms vs 296 ± 52 ms, p = 0.002), with no difference between the GL and NL groups (325 ± 96 vs 296 ± 52 ms, p = NS). Of the patients with 1-to-1 AP conduction of <270 ms, none (0 of 11) were in the SL group compared to 18 of 47 in the NL group (p = 0.0017), with no significant difference in the GL group (5 of 18) compared to the NL group (p = NS). The patients in the GL group were more likely to have a left-sided AP (14 of 18) than the NL group (17 of 47, p = 0.002) and the SL group (3 of 11, p = 0.002). In conclusion, a sudden loss of preexcitation during an EST predicted a long cycle length with 1-to-1 conduction by way of the AP. Also, the AP conduction characteristics in patients with GL compared to those with NL did not differ, and the GL of preexcitation was more frequently seen in patients with a left-sided AP.

The age-related discrepancy in the effect of neuropeptide Y on select catecholamine biosynthetic enzymes in the adrenal medulla and hypothalamus in rats

The elevated levels of circulating catecholamines (CAs) with age may be related to the increased expression of CA biosynthetic enzymes, tyrosine hydroxylase (TH) and dopamine beta hydroxylase (DbetaH) in the adrenal medulla of senescent compared with younger animals. Neuropeptide Y (NPY) is co-synthesized and co-released with CAs in the adrenal medulla. NPY inhibits the stimulated secretion of CAs, however, its role in regulation of the genes encoding CA biosynthetic enzymes is not clear. We hypothesized that NPY up-regulates TH, DbetaH and NPY expression in the adrenal medullae of young and old Fischer-344 rats. NPY increased mRNA expression of TH, DbetaH, NPY and also enhanced TH protein level in the adrenal medullae of young rats by 50%, 35%, 45% and by 20%, respectively. We also examined the effect of NPY on TH and NPY mRNA in the hypothalamus. Basal expression of TH mRNA was decreased in the hypothalamus with age. DNA binding activities of activator protein-1 and cAMP response element binding protein were also augmented only in the young by 140% and 125%, respectively. We conclude that NPY stimulates the CA biosynthetic pathway in the adrenal medulla and positive auto-regulation of NPY might be involved in this process. The stimulatory effect of NPY on adrenomedullary CA biosynthetic pathway is blunted with age.