Minimizing Device-Device Interactions Using Bipolar Pacemaker Leads in a Pediatric Patient.

Phrenic nerve injury can lead to a disruption of the autonomic nervous system (ANS) resulting in episodes of bradycardic arrest. Implanted diaphragmatic pacing has been used to overcome phrenic nerve paralysis, but these do not change the ANS. Therefore, patients with phrenic nerve paralysis may require the implantation of a permanent cardiac pacemaker to overcome bradycardic episodes. Having two electronic devices in the same patient may lead to device-device interaction (DDI). This can result in over-sensing leading to lack of pacing of either device. We present the case of a 17-year-old pediatric male with phrenic nerve injury who required implantation of both diaphragm and cardiac pacemaker. Intra-procedural interrogation of the cardiac pacemaker demonstrated DDI in unipolar mode, but not in bipolar. Thus, we demonstrated the safe utilization of multiple implantable electronic devices in the pediatric patient without device-device interaction.

Epicardial atrial pacing after the extracardiac Fontan operation: Feasibility of an entirely transvenous approach.

This series describes an innovative technique for pacing in patients with sinus node dysfunction after extracardiac Fontan surgery. This transpulmonary approach to the left atrial epi-myocardium has been successfully applied to three patients at two centers and resulted in excellent acute and midterm pacing characteristics without known complications. The principal advantage of this procedure in comparison to prior iterations is the absence of pacing material within the pulmonary venous atrium, so that future systemic thromboembolism risk is minimized. The transpulmonary approach for permanent atrial pacing offers a novel solution to the unique challenges for patients after extracardiac Fontan operation.

Polarization-sensitive optical coherence tomography monitoring of percutaneous radiofrequency ablation in left atrium of living swine.

Radiofrequency ablation (RFA) is commonly used to treat atrial fibrillation (AF). However, the outcome is often compromised due to the lack of direct real-time feedback to assess lesion transmurality. In this work, we evaluated the ability of polarization-sensitive optical coherence tomography (PSOCT) to measure cardiac wall thickness and assess RF lesion transmurality during left atrium (LA) RFA procedures. Quantitative transmural lesion criteria using PSOCT images were determined ex vivo using an integrated PSOCT-RFA catheter and fresh swine hearts. LA wall thickness of living swine was measured with PSOCT and validated with a micrometer after harvesting the heart. A total of 38 point lesions were created in the LA of 5 living swine with the integrated PSOCT-RFA catheter using standard clinical RFA procedures. For all lesions with analyzable PSOCT images, lesion transmurality was assessed with a sensitivity of 89% (17 of 19 tested positive) and a specificity of 100% (5 of 5 tested negative) using the quantitative transmural criteria. This is the first report of using PSOCT to assess LA RFA lesion transmurality in vivo. The results indicate that PSOCT may potentially provide direct real-time feedback for LA wall thickness and lesion transmurality.

Symptomatic atrial bigeminy masquerading as congenital complete heart block.

Newborn male with symptomatic bradycardia initially diagnosed with complete atrioventricular block. Isoproterenol drip was initiated, and the patient was scheduled for pacemaker implantation. During the hospital course, repeat electrocardiogram and Holter monitor revealed evidence of near continuous blocked atrial bigeminy with occasional aberrantly conducted premature atrial contractions. Flecainide was started, resulting in normal sinus rhythm, and the pacemaker implantation was cancelled.

Diagnostic Accuracy and Safety of Confirm Rx™ Insertable Cardiac Monitor in Pediatric Patients.

Insertable cardiac monitors (ICM) are subcutaneously implanted devices that monitor a patient's heart rate and rhythm (Rossano in Pediatrics 112(3):e228, 2003). The diagnostic accuracy and safety of the Confirm RxTM (Abbott, Minneapolis, MN) ICM in pediatric patients is unknown. This is a single center, retrospective, IRB-approved review of patients ≤ 21 years implanted with Confirm RxTM ICMs from 2017 to 2020. Data collected included demographics, indications, presence of P-wave and R-wave amplitude at implantation and follow-up, number/appropriateness of transmissions pre and post implementation of SharpSenseTM technology, reprogramming to improve accuracy, time from implantation to arrhythmia detection, and complications. There were 29 patients (median age: 8 years, 59% females). P-waves were identified in all patients and average R-wave amplitude was 0.85 mV (0.26-1.03 mV). There was no significant difference in R-wave amplitude based on size (BSA ≥ 1.5 m2: 0.76 mV, < 1.5 m2: 0.91 mV) or congenital heart disease (+CHD: 0.86 mV, -CHD: 0.85 mV). Arrhythmias identified were the following: wide complex tachycardia (1), supraventricular tachycardia (4), bradycardia/sinus pause (3), and premature ventricular contraction (1). SharpSenseTM implementation decreased the false-positive rate in device-initiated transmissions (55.4% to 0%, p < 0.00001). Average time from implantation to arrhythmia detection was 2.63 months (range: 0-8.8). A single complication of cellulitis occurred. Confirm RxTM is appropriate for implant in pediatric patients regardless of age, BSA, or CHD. Implementation of SharpSense™ technology dramatically decreased the false-positive rate. Follow-up studies could utilize additional monitoring devices to provide analysis on potential events that the Confirm RxTM ICM missed.

Ventricular tachycardia recorded in a competitive swimmer using Confirm Rx™ loop recorder.

Conventional ambulatory heart rhythm monitoring is limited in its ability to provide rapid diagnosis of arrhythmias in athletes participating in water or high-intensity sports. This case report is of a 17-year-old female competitive swimmer who underwent loop recorder implantation with Confirm Rx™ ICM 3500 (Abbott, Minneapolis, MN) to monitor for arrhythmias during swimming. The purpose of this case report is to describe the utility of implantable loop recorders in arrhythmia diagnosis and symptom evaluation in water sport athletes.

Automated external defibrillator use in a previously healthy 31-day-old infant with out-of-hospital cardiac arrest due to ventricular fibrillation.

INTRODUCTION: Current resuscitation guidelines state that the safety of automated external defibrillators (AEDs) in infants less than 1 year of age is unknown. METHODS AND RESULTS: We report successful AED use in a 31-day-old previously healthy infant with out-of-hospital cardiac arrest. Chest compressions began immediately, pediatric AED pads were applied in less than 5 minutes and the initial rhythm was ventricular fibrillation. After two 50 J shocks, return of spontaneous circulation was achieved. She was diagnosed with a rare but previously described syndrome of infant ventricular fibrillation and was discharged to home in good condition after epicardial defibrillator placement. CONCLUSIONS: This case represents, to our knowledge, the youngest patient successfully defibrillated by an AED in a nonmedical setting. Although she received two shocks more than 11 J/kg each, she had no apparent myocardial damage at presentation.

Coronary Artery Evaluation by Screening Echocardiogram in Intercollegiate Athletes.

INTRODUCTION: Coronary artery anomalies are the second most common congenital cause of sudden cardiac death in young athletes. Some centers have advocated for limited transthoracic echocardiogram (TTE) protocols in the screening of college athletes, which may miss important causes of sudden cardiac death. PURPOSE: The purpose of this study was to evaluate the ability of screening TTE to determine the origin and proximal course of the coronary arteries in intercollegiate athletes. METHODS: An institutional review board-approved retrospective review of all incoming National Collegiate Athletic Association Division-I athletes at a single institution for the 2013-2014 academic year was performed. Two pediatric cardiologists independently reviewed all TTE studies for right coronary artery (RCA) and left coronary artery (LCA) ostia, proximal course, and measurable course. Proximal course was defined as a measurable course >1 cm for the RCA and a measurable course >1 cm or observation of the bifurcation for the LCA. Measurable course was defined as the maximum continuously observable distance of coronary artery from a clearly delineable ostium. Results were compared among athlete characteristics, and interobserver reliability was evaluated. RESULTS: Chart review identified 146 athletes, representing 22 sports and 6 ethnicities. No coronary anomalies were found. The average measurable course was 2.1 cm for the RCA and 1.5 cm for the LCA. Both readers observed the RCA ostium in 143 athletes (98%), LCA ostium in 143 athletes (98%), RCA proximal course in 119 athletes (82%), and LCA proximal course in 118 athletes (81%). Statistical analysis showed good interobserver reliability for observation of the ostia and proximal course. CONCLUSIONS: The origin and proximal course of the coronary arteries were readily and reliably observed in the majority of athletes, suggesting coronary artery evaluation should be included in athlete screening TTE protocols.

Endurance Training on Congenital Valvular Regurgitation: An Athlete Case Series.

BACKGROUND: Both intense endurance training and valvular regurgitation place a volume load on the right and left ventricles, potentially leading to dilation, but their effects in combination are not well-known. PURPOSE: The purpose of this case series is to describe the combined volume load of intense endurance athletic training and regurgitant valvular disease as well as the challenging assessment of each component's cardiovascular effect. METHODS: In this article, the clinical course of three elite endurance athletes with congenital valvular disease were reviewed. RESULTS: A swimmer with aortic regurgitation, a cyclist with aortic regurgitation, and a cyclist with pulmonary regurgitation were found to have severe dilation of the associated ventricles despite continuing to train at an elite level without symptoms. CONCLUSIONS: Because of the cumulative effects of endurance training and valvular regurgitation, each athlete manifested ventricular dilation out of proportion to their valvular disease and symptoms. Although the effects of congenital valvular disease and athletic remodeling on ventricular dilation have been thoroughly studied individually, their cumulative effect is not well understood. This complicates the assessment of athletes with valvular regurgitation and underscores the need for athlete-specific recommendations for valve replacement.

The Historical Perspective of Athletic Sudden Death.

Since antiquity, the athlete has been elevated to a heroic status both within small communities and at the international level. Although numerous population studies have estimated athletic sudden death to be a rare event, the consequences resonate far beyond those directly affected. Sports cardiology has evolved as a result of these tragedies, which highlighted a need for safer play and more programmatic protection of the athlete in play. In this article, athletic sudden death is analyzed from a historical and literary perspective and the development of modern initiatives to protect athletes from sudden death is reviewed.

T-wave reversion in pediatric patients during exercise stress testing.

OBJECTIVE: T-wave inversion in lateral electrocardiogram (ECG) leads (II, III, aVF, V4 -V6 ) is suspicious of cardiac pathology in pediatric patients, though many are found to have structurally normal hearts. The purpose of this study is to evaluate T-wave response during exercise stress testing (EST) in pediatric patients with structurally normal hearts and lateral-lead T-wave inversion on resting ECG. DESIGN: An IRB-approved, retrospective review of EST databases at two centers identified patients with lateral-lead T-wave inversion on resting ECG. Inclusion criteria were normal exam and echocardiogram, absence of anginal chest pain, and age <18 years. All patients underwent treadmill or cycle ergometer EST. Data recorded included demographics, echocardiogram results, baseline ECG, EST method, peak heart rate and metabolic equivalents (METs), and heart rate and METs at T-wave reversion. T-wave reversion was considered complete if T-waves reverted in all leads, partial if reversion occurred in only some leads, and none if no reversion occurred. RESULTS: The search identified 14 patients: nine females and five males (10 Caucasians and four African Americans) and an average age of 16 (range 12-18) years. Complete T-wave reversion occurred in 11 (79%) patients, partial in two (14%), and none in one (7%). Reversion occurred in both genders, ethnicities, and EST methods. No complications occurred during EST; no adverse outcomes occurred during 2-year follow-up. CONCLUSIONS: EST in pediatric patients with lateral-lead T-wave inversion on resting ECG and structurally and functionally normal hearts resulted in either complete or partial T-wave reversion in the vast majority of patients.

Induction of atrial fibrillation with adenosine during a transesophageal electrophysiology study to risk stratify a patient with asymptomatic ventricular preexcitation.

An asymptomatic adolescent male athlete was incidentally found to have ventricular preexcitation on electrocardiogram during a sports preparticipation physical. A transesophageal electrophysiology study (TEEPS) was performed after an exercise stress test failed to delineate the patient's risk of sudden cardiac death. The TEEPS was favored in this case over a transvenous electrophysiology study due to reduced invasiveness. The goal of the TEEPS was to place the patient into atrial fibrillation (AFib) and evaluate the shortest preexcited RR interval during AFib, thereby assessing the risk of his accessory pathway. Conventional pacing modalities were unable to induce AFib. During atrial burst pacing, adenosine was then administered, which successfully induced AFib. This case highlights adenosine's potential to induce atrial fibrillation during transesophageal electrophysiology studies when atrial pacing alone was unable to do so.

Atrial fibrillation induction by transesophageal electrophysiology studies in patients with asymptomatic ventricular preexcitation.

OBJECTIVE: Ventricular preexcitation is a conduction abnormality caused by an accessory pathway bridging the atria and ventricles. If the accessory pathway conducts rapidly during atrial fibrillation (AFib), sudden death may result. The purpose of this study was to determine the ability of transesophageal electrophysiology studies (TEEPS) to induce AFib in pediatric patients with asymptomatic ventricular preexcitation (aVPE). DESIGN: A retrospective review of patients with aVPE who had a TEEPS was conducted. Inclusion criteria were evidence of ventricular preexcitation on electrocardiogram; age <18 years; and no history of tachycardia, palpitations, or syncope. Data gathered included age, weight, height, form of sedation, and TEEPS results. If AFib was induced, patients were classified as at risk of sudden death if the shortest preexcited RR interval during AFib was <250 ms or no risk if ≥ 250 ms. RESULTS: A total of 26 patients met the inclusion criteria, with average age of 11.9 years, weight of 48.9 kg, and height of 149.2 cm. During the procedure, nine patients underwent conscious sedation (34.6%), and 17 underwent general anesthesia (65.4%). AFib was induced in 23 patients (88.5%), of whom 17 (73.9%) had no risk and six (26.1%) had risk. No statistical differences were noted in age, weight, height, or form of sedation when comparisons were made between AFib induction and no AFib induction. CONCLUSIONS: TEEPS induced AFib in 88.5% of patients. Age, weight, height, and form of sedation had no effect upon AFib inducibility. TEEPS is an effective modality to induce AFib in pediatric patients with aVPE.