Subcutaneous cardioverter-defibrillator implantation in an adult with congenital heart disease and left infra-mammary pacemaker.

The approach/type of an implantable cardioverter defibrillator (ICD) is determined by the underlying cardiac anatomy, venous access, and pre-existing cardiac implantable electronic devices. We describe a case of subcutaneous ICD implantation in an adult with congenital heart disease (CHD) with a pre-existing inframammary transvenous pacemaker. This was preferred over adding a defibrillator coil to existing pacing leads, extraction/replacement of pacing system, or a sternotomy/epicardial ICD placement. The procedure was accomplished uneventfully with successful defibrillation threshold testing. Innovative approaches are required to manage arrhythmias in adults with CHD, with shared decision making playing a critical role.

Significance of electrocardiogram abnormalities in children presenting to the emergency department with acute COVID-19 infection.

OBJECTIVES: Acute COVID-19 infection may be associated with electrocardiogram (EKG) abnormalities in pediatric patients. We have anecdotally observed EKG abnormalities in patients without MIS-C or significant cardiac disease requiring intervention or further follow-up. Our aim was to determine the incidence of abnormal EKG findings and correlate with evidence of significant cardiac pathology in pediatric patients who present to the emergency department during an acute COVID-19 infection. METHODS: We conducted a retrospective chart review of 209 pediatric patients diagnosed in the emergency department with acute COVID-19 infection and had an EKG during the same encounter; patients with MIS-C were excluded. Primary objectives included determination of the incidence of EKG abnormalities in patients presenting to the emergency department (ED) with acute COVID-19 infection who did not require hospitalization. Secondary objectives included correlation of these findings with other concomitant testing of possible cardiac pathology (echocardiograms, biomarkers), and clinical outcomes. RESULTS: EKG abnormalities were identified in 84 (40%) patients. Echo was performed in 28 (13.4%) patients; only 1 was abnormal, and considered an incidental finding. The most common EKG abnormality involved nonspecific ST-T wave patterns, suggestive of but not diagnostic for underlying pericardial or myocardial disease. Serum troponin and BNP values were normal in all patients tested, either with a normal or abnormal EKG. A normal EKG had a 100% sensitivity and negative predictive value in predicting a normal echocardiogram. No patients were hospitalized and there was normalization of EKG abnormalities during short-term follow up. CONCLUSIONS: Despite a high incidence of abnormal EKG repolarization patterns in pediatric patients presenting with acute (non-MIS-C) COVID-19 infections, these patients generally do not have abnormal cardiac biomarkers or echocardiograms, and the risk for adverse cardiac events is low.

Myocardial bridge in a child with cardiac arrest and ventricular fibrillation: a bridge over troubled water?

Resuscitated cardiac arrest in a child triggers a comprehensive workup to identify an aetiology and direct management. The presence of a myocardial bridge does not automatically imply causation. Careful determination of the haemodynamic significance of the myocardial bridge is critical to avoid an unnecessary sternotomy and to provide appropriate treatment.

N-terminal pro-B-type-natriuretic peptide as a screening tool for pulmonary hypertension in the paediatric population.

BACKGROUND: Although cardiac catheterisation (cath) is the diagnostic test for pulmonary hypertension, it is an invasive procedure. Echocardiography (echo) is commonly used for the non-invasive diagnosis of pulmonary hypertension but maybe limited by lack of adequate signals. Therefore, emphasis has been placed on biomarkers as a potential diagnostic tool. No prior paediatric studies have simultaneously compared N-terminal pro-B-type-natriuretic peptide (NTproBNP) with cath/echo as a potential diagnostic tool. The aim of this study was to determine if NTproBNP was a reliable diagnostic tool for pulmonary hypertension in this population. METHODS: Patients were divided into Study (echo evidence/established diagnosis of pulmonary hypertension undergoing cath) and Control (cath for small atrial septal defect/patent ductus arteriosus and endomyocardial biopsy post cardiac transplant) groups. NTproBNP, cath/echo data were obtained. RESULTS: Thirty-one patients met inclusion criteria (10 Study, 21 Control). Median NTproBNP was significantly higher in the Study group. Echo parameters including transannular plane systolic excursion z scores, pulmonary artery acceleration time and right ventricular fractional area change were lower in the Study group and correlated negatively with NTproBNP. Receiver operation characteristic curve analysis demonstrated NTproBNP > 389 pg/ml was 87% specific for the diagnosis of pulmonary hypertension with the addition of pulmonary artery acceleration time improving the specificity. CONCLUSIONS: NTproBNP may be a valuable adjunctive diagnostic tool for pulmonary hypertension in the paediatric population. Echo measures of transannular plane systolic excursion z score, pulmonary artery acceleration time and right ventricular fractional area change had negative correlations with NTproBNP. The utility of NTproBNP as a screening tool for pulmonary hypertension requires validation in a population with unknown pulmonary hypertension status.

Myocardial deformation as a predictor of right ventricular pacing-induced cardiomyopathy in the pediatric population.

INTRODUCTION: Right ventricular pacing is associated with pacemaker induced cardiomyopathy and lesser degrees of pacing-induced LV dysfunction (PIVD) manifested by a reduction in left ventricular ejection fraction (LVEF). Our objective was to determine whether apical 4 chamber strain (A4C) by echocardiography can identify patients at risk of PIVD before LVEF declines. METHODS AND RESULTS: A retrospective chart review of patients (0-21 years) who had a pacemaker with a ventricular lead placed between 2011 and 2017 was performed. Patients were divided into group A (LVEF <55% and/or >10% decline in LVEF within 12 months of pacemaker placement) and group B. Data have collected before and 1 and 12 months postpacemaker implantation. There were 30 patients in the group A and 60 in group B. At 1 and 12 months postpacemaker implantation, the LVEF was significantly lower while the A4C and QRS duration on electrocardiogram were significantly higher in the group A. While the LVEF and A4C became markedly abnormal in group A as early as 1 month, the A4C did not seem to demonstrate such marked abnormalities in group B. However, a sub-analysis of patients in the group A with preserved LVEF at 1 month demonstrated significant worsening in their A4C at that time. CONCLUSION: Myocardial deformation imaging may be a clinically useful tool for the prediction of a decline in LV systolic function following pacemaker implantation. Abnormalities in A4C seem to appear before LVEF decline and as soon as 1-month postpacemaker implantation.

Chemical cardioversion of atrial flutter and fibrillation in the pediatric population with Ibutilide.

INTRODUCTION: Atrial flutter (AFL) and atrial fibrillation (AF) are common in pediatric patients with congenital heart disease and structurally normal hearts as well. Chemical cardioversion is attractive for patients with AFL/AF for a short period of time because of the ability to avoid sedation. We review a single center's experience with Ibutilide in pediatric patients in an effort to report on its safety and efficacy. METHODS: We performed a retrospective chart review of pediatric patients (0-21 years) who underwent chemical cardioversion for AFL/AF with Ibutilide (January 2011-February 2019). Patients on another antiarrhythmic medication or attempted chemical cardioversion with another drug were excluded. RESULTS: There were 21 patients who met inclusion criteria. Thirteen of the 21 (62%) patients were successfully cardioverted with Ibutilide (10 out of 13 had AF and four out of 13 required a second dose). There were no significant differences in baseline characteristics between those who were successfully cardioverted compared to those who were not. Administration of magnesium prior to administration did not appear to have an effect on the success rate. There was a significant increase in rate corrected QT interval (QTc) post Ibutilide administration, which returned to baseline prior to discharge. One patient had symptomatic bradycardia needing intravenous fluids and another had torsades requiring electrical cardioversion during Ibutilide administration. CONCLUSIONS: The success rate of chemical cardioversion with Ibutilide was similar in our experience as compared to studies in the adult population and the other lone pediatric study. Although adverse events were uncommon, Ibutilide administration warrants close monitoring and fully defining its efficacy warrants further pediatric experience.

Cardiomegaly on chest radiographs as a predictor of heart disease in the pediatric population.

BACKGROUND: Cardiomegaly on chest radiographs (CXR) in pediatric patients leads to multiple tests. We aimed to determine the positive predictive value (PPV) of cardiomegaly on CXR in predicting subsequent heart disease and to assess the utility of obtaining a B-type Natriuretic Peptide level (BNP) and/or electrocardiogram (EKG) in such patients. We hypothesized that an echocardiogram may not be appropriate in all cases of cardiomegaly on CXR, particularly in a patient with a normal EKG and BNP level. METHODS: We performed a retrospective cohort study of pediatric patients with cardiomegaly on their initial CXR between January 2015-December 2017. Patients without a subsequent echocardiogram or known congenital heart disease were excluded. A patient was deemed to have heart disease if they had structural abnormalities, functional abnormalities or a pericardial effusion on echocardiogram. The PPV of CXR and the PPV/NPV of the other tests (EKG, BNP) were calculated using contingency tables. RESULTS: Four hundred and eighty nine patients met inclusion criteria. The PPV of cardiomegaly on CXR alone without any other diagnostic testing in predicting subsequent heart disease was 15%. The PPV increased if there was either an abnormal EKG or a BNP >100 pg/ml and further increased if both of these were present. The PPV values were higher in patients <1 year of age. CONCLUSIONS: Cardiomegaly on CXR can often predict the presence of heart disease, particularly in infants. Further testing with EKG and BNP can better predict who may have heart disease, but it may not eliminate the need for echocardiography.

Recurrent single echo beats after cryoablation of atrioventricular nodal reentrant tachycardia: The pediatric population.

BACKGROUND: Cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is effective and safe with a reported limitation of lower success and higher recurrence rates. We have observed cases in which slow pathway conduction was eliminated as demonstrated by atrial extra-stimulus testing within 1 min of cryo-energy delivery but returned following tissue rewarming. Frequently, slow pathway conduction persisted despite multiple acutely successful lesions over a broad anatomic region. We aimed to determine if return of slow pathway conduction after elimination during cryoablation represents a risk for recurrent AVNRT with the same intermediate term results as slow pathway ablation. We hypothesize that remnant single echo beats in the absence of sustained slow pathway conduction and inducible AVNRT is an acceptable end point after clear slow pathway elimination during cryoablation. METHODS: Retrospective chart review of patients undergoing attempted slow pathway ablation for AVNRT using solely cryoablation between January 2015-January 2018. RESULTS: Forty-four patients met inclusion criteria with at-least 2 features of dual AVN physiology. 19 patients had return of slow pathway conduction shortly after clear elimination during cryoablation (Group A) while 25 did not (Group B). All in Group A had recurrent single echo beats but none had sustained slow pathway conduction at the end of the procedure nor AVNRT recurrence at 1 year. CONCLUSION: Recurrent single echo beats with absent sustained slow pathway conduction and non-inducible AVNRT may be an acceptable endpoint for slow pathway ablation of AVNRT using cryoablation when there is elimination of slow pathway demonstrated during energy delivery.

Exercise stress echocardiography: Impact on clinical decision-making in pediatric patients.

BACKGROUND: The role of exercise stress echocardiography (ESE) in the pediatric population is less well defined as compared to adults. We aimed to determine the utility and impact of ESE on clinical decision-making in pediatric patients. METHODS: We identified patients who underwent an ESE at our center from 2011 to 2015. Test indications were categorized into symptoms with exercise; sports/activity clearance; hypertrophic cardiomyopathy (HCM) or suspected HCM; coronary anomalies; or abnormal electrocardiogram (EKG). Change in clinical management was assessed by comparing pre- and post-test activity restrictions, which were categorized into unrestricted from exercise or activity; restricted from exercise or activity; and surgical referral. RESULTS: During the study period, 353 ESEs met inclusion criteria. Of all ESEs performed, 263 (75%) were normal. Clinical management changed as a result of ESE in 144 (40%). Of the abnormal ESEs, 44 were restricted from activity, including 25 (56.8%) restricted from competitive or varsity athletics, 14 (31.8%) restricted from recreational sports, and 5 (11.4%) restricted from all activity. Surgical referrals included valve repair/replacement in 7 (50%), ICD placement in 5 (35.8%), coronary re-implantation in 1 (7.1%), and atrial septal defect repair in 1 (7.1%). CONCLUSION: Exercise stress echocardiography provides the pediatric cardiologist with useful information that impacts management in a wide variety of cardiac disorders. Clinical management changed in nearly half the patients that were subjected to an ESE at our center. This supports the value of ESE for informing clinical decision-making. Future studies should aim to refine patient selection and examine its impact on patient outcomes.

Voltage mapping to guide pacemaker placement in patients with CHD.

Transvenous pacemaker implantation for sinus node dysfunction in patients with Fontan palliation presents the difficulty of finding suitable pacing tissue and the potential of causing vascular obstruction in a low-flow circuit. We describe a patient who underwent electro-anatomic voltage mapping to guide a transvenous single chamber lead within her Fontan baffle. This highlights the use of advanced mapping technologies for pacemaker implantation in complex cyanotic heart disease.

Protective effects of amniotic fluid in the setting of necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is the most common life threatening condition affecting preterm infants. NEC occurs in 1-5% of all neonatal intensive care admissions and 5-10% of very low birth weight infants. The protective role of human breast milk (BM) has been well established. It has also been shown that amniotic fluid (AF) and BM have many similarities in terms of presence of growth and other immune-modulatory factors. This finding led to the initial hypothesis that AF may exert similar protective effects against the development of NEC, as does BM. Multiple studies have elucidated the presence of growth factors in AF and the protective effect of AF against NEC. Studies have also described possible mechanisms how AF protects against NEC. At present, research in this particular area is extremely active and robust. This review summarizes the various studies looking at the protective effects of AF against the development of NEC. It also provides an insight into future directions, the vast potential of AF as a readily available biologic medium, and the ethical barriers that must be overcome before using AF.

Combination Therapy of Ivabradine with Procainamide for the Management of Pediatric Postoperative Junctional Ectopic Tachycardia.

Pediatric postoperative junctional ectopic tachycardia (JET), although usually self-limited, may lead to significant morbidity and mortality. Anti-arrhythmic medications are often necessary to restore atrioventricular synchrony when non-pharmacological measures fail. Multiple drugs have been described for the management of postoperative JET, with enteral ivabradine being the latest addition. While safe administration of ivabradine has been described in combination with other anti-arrhythmics (amiodarone, flecainide), no study has described the use of ivabradine in conjunction with intravenous procainamide for the management of postoperative JET. Our case report describes the safe use of ivabradine and procainamide combination therapy in a young patient.

Lead Management in Patients with Congenital Heart Disease.

Pediatric patients with congenital heart disease present unique challenges when it comes to cardiac implantable electronic devices. Pacing strategy is often determined by patient size/weight and operator experience. Anatomic considerations, including residual shunts, anatomic obstructions and barriers, and abnormalities in the native conduction system, will affect the type of CIED implanted. Given the young age of patients, it is important to have an "eye on the future" when making pacemaker/defibrillator decisions, as one can expect several generator changes, lead revisions, and potential lead extractions during their lifetime.

Left Main Coronary Artery Ostial Stenosis in a Pediatric Patient With Sudden Cardiac Arrest.

Pediatric resuscitated sudden cardiac arrest may result from diverse conditions and, therefore, warrants a comprehensive work-up. Although rare, coronary artery abnormalities must be ruled out in these patients. We describe a case with congenital left main coronary artery ostial stenosis diagnosed using advanced imaging techniques. (Level of Difficulty: Advanced.).

Clinical risk prediction score for postoperative accelerated junctional rhythm and junctional ectopic tachycardia in children with congenital heart disease.

BACKGROUND: Accelerated junctional rhythm (AJR) and junctional ectopic tachycardia (JET) are common postoperative arrhythmias associated with morbidity/mortality. Studies suggest that pre- or intraoperative treatment may improve outcomes, but patient selection remains a challenge. OBJECTIVES: The purpose of this study was to describe contemporary outcomes of postoperative AJR/JET and develop a risk prediction score to identify patients at highest risk. METHODS: This was a retrospective cohort study of children aged 0-18 years undergoing cardiac surgery (2011-2018). AJR was defined as usual complex tachycardia with ≥1:1 ventricular-atrial association and junctional rate >25th percentile of sinus rate for age but <170 bpm, whereas JET was defined as a rate >170 bpm. A risk prediction score was developed using random forest analysis and logistic regression. RESULTS: Among 6364 surgeries, AJR occurred in 215 (3.4%) and JET in 59 (0.9%). Age, heterotaxy syndrome, aortic cross-clamp time, ventricular septal defect closure, and atrioventricular canal repair were independent predictors of AJR/JET on multivariate analysis and included in the risk prediction score. The model accurately predicted the risk of AJR/JET with a C-index of 0.72 (95% confidence interval 0.70-0.75). Postoperative AJR and JET were associated with prolonged intensive care unit and hospital length of stay, but not with early mortality. CONCLUSION: We describe a novel risk prediction score to estimate the risk of postoperative AJR/JET permitting early identification of at-risk patients who may benefit from prophylactic treatment.

Ventricular arrhythmias after fibroma resection: Are patients still at risk?

BACKGROUND: Ventricular fibromas frequently present with life-threatening ventricular tachycardia (VT) or ventricular fibrillation (VF) in children. The long-term risk of sustained ventricular arrhythmias after surgical resection is unknown. OBJECTIVES: The aims of this study were to quantify the VT/VF risk after surgical resection and to examine the results of early (during index surgical hospitalization) and late (≥3 months after surgery) postoperative ventricular stimulation (V-stim) studies. METHODS: We performed a retrospective cohort study of all patients with ventricular fibromas who underwent surgical resection at our institution (2000-2020). The primary outcome was defined as recurrent VT/VF ≥3 months after index surgical resection. RESULTS: Forty-six patients with a median age at surgery of 2 years (range 0.3-18.9 years) formed our study cohort. Indications for surgery included cardiac arrest in 11 (24%), sustained VT in 16 (35%), premature ventricular contractions/nonsustained VT in 10 (22%), and hemodynamic abnormalities in 9 (20%). Of the 11 patients who presented with cardiac arrest, 4 underwent pre-resection implantable cardioverter-defibrillator (ICD) implantation, all of which were explanted at the time of surgery. An early postoperative V-stim study was performed in 26 (57%) patients, and all were negative for inducible VT/VF. Of the 13 late postoperative V-stim studies, 3 were positive: 2 underwent ICD implantation and 1 was initiated on amiodarone and underwent loop recorder implantation. At the time of last follow-up (median 1.5 years; range 0.3-16.5 years), 45 (98%) were free of clinical VT/VF and no patient with an ICD has received an appropriate shock. CONCLUSION: Surgical resection of ventricular fibromas significantly reduces the risk of life-threatening arrhythmias in children; however, a small number of patients remain vulnerable.

Non-fluoroscopic Techniques for Catheter Ablation of Typical Atrioventricular Nodal Re-entry Tachycardia in a Pediatric Patient with Atypical Venous Anatomy.

Catheter ablation of the slow pathway to the atrioventricular node is generally a safe and effective treatment for atrioventricular nodal re-entry tachycardia (AVNRT). However, congenital anomalies of the inferior vena cava and superior draining veins can limit traditional catheter approaches to the right heart from femoral venous access and distort local anatomy within the triangle of Koch, necessitating alternative electrophysiology (EP) mapping and ablation strategies. Despite the widespread availability of non-fluoroscopic 3-dimensional imaging systems, many providers still rely on venography to describe unusual cardiovascular anatomy and fluoroscopy to position EP catheters when mapping and ablating the slow pathway. Herein, we report our experience with a pediatric patient with inducible AVNRT and atypical venous anatomy in whom slow pathway ablation was performed successfully without the use of fluoroscopy. In addition, we describe the modification of a novel mapping technique for targeting the slow pathway for ablation.