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.

Flecainide Is Associated With a Lower Incidence of Arrhythmic Events in a Large Cohort of Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

BACKGROUND

In severely affected patients with catecholaminergic polymorphic ventricular tachycardia, beta-blockers are often insufficiently protective. The purpose of this study was to evaluate whether flecainide is associated with a lower incidence of arrhythmic events (AEs) when added to beta-blockers in a large cohort of patients with catecholaminergic polymorphic ventricular tachycardia.

METHODS

From 2 international registries, this multicenter case cross-over study included patients with a clinical or genetic diagnosis of catecholaminergic polymorphic ventricular tachycardia in whom flecainide was added to beta-blocker therapy. The study period was defined as the period in which background therapy (ie, beta-blocker type [beta1-selective or nonselective]), left cardiac sympathetic denervation, and implantable cardioverter defibrillator treatment status, remained unchanged within individual patients and was divided into pre-flecainide and on-flecainide periods. The primary end point was AEs, defined as sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter defibrillator shock, and arrhythmic syncope. The association of flecainide with AE rates was assessed using a generalized linear mixed model assuming negative binomial distribution and random effects for patients.

RESULTS

A total of 247 patients (123 [50%] females; median age at start of flecainide, 18 years [interquartile range, 14-29]; median flecainide dose, 2.2 mg/kg per day [interquartile range, 1.7-3.1]) were included. At baseline, all patients used a beta-blocker, 70 (28%) had an implantable cardioverter defibrillator, and 21 (9%) had a left cardiac sympathetic denervation. During a median pre-flecainide follow-up of 2.1 years (interquartile range, 0.4-7.2), 41 patients (17%) experienced 58 AEs (annual event rate, 5.6%). During a median on-flecainide follow-up of 2.9 years (interquartile range, 1.0-6.0), 23 patients (9%) experienced 38 AEs (annual event rate, 4.0%). There were significantly fewer AEs after initiation of flecainide (incidence rate ratio, 0.55 [95% CI, 0.38-0.83]; P=0.007). Among patients who were symptomatic before diagnosis or during the pre-flecainide period (n=167), flecainide was associated with significantly fewer AEs (incidence rate ratio, 0.49 [95% CI, 0.31-0.77]; P=0.002). Among patients with ≥1 AE on beta-blocker therapy (n=41), adding flecainide was also associated with significantly fewer AEs (incidence rate ratio, 0.25 [95% CI, 0.14-0.45]; P<0.001).

CONCLUSIONS

For patients with catecholaminergic polymorphic ventricular tachycardia, adding flecainide to beta-blocker therapy was associated with a lower incidence of AEs in the overall cohort, in symptomatic patients, and particularly in patients with breakthrough AEs while on beta-blocker therapy.

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.

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.

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.

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.

Comparison of the Medtronic SelectSecure and conventional pacing leads: Long-term follow-up in a multicenter pediatric and congenital cohort

INTRODUCTION

The Medtronic SelectSecure™ (Minneapolis, MN, USA) pacing lead (SS) has theoretical advantages compared to conventional (C) transvenous pacing leads (PLs). The study purpose was to determine whether differences in electrical function and lead survival exist between these PLs in a large data set of pediatric and congenital patients.

METHODS

A multicenter historical longitudinal cohort study was performed comparing SS and CPL performance over a 72-month follow-up (FU). Ten centers provided data for both SS and CPL, matched for age, implanted pacing chamber, time period of implantation, and presence of heart disease.

RESULTS

The cohort consisted of 141 subjects in each group. No statistical differences were observed in age, gender, presence of heart disease, or pacing indication. Atrial and ventricular capture thresholds were stable throughout FU and higher in the SS group (atrial: 0.75 ± 0.02 vs 0.5 ± 0.04 V, ventricular: 1.0 ± 0.04 vs 0.75 ± 0.04 V), P < 0.001. Group PL sensing thresholds did not differ. The SS group required greater energy to pace (atrial: 0.57 ± 0.05 vs 0.32 ± 0.02 mJ, ventricular: 0.83 ± 0.05 vs 0.56 ± 0.06 mJ), P = 0.001. Early lead dislodgement and phrenic nerve stimulation were greater in the SS group (P = 0.03). Long-term lead survival was high and similar between the two groups, P = 0.35.

CONCLUSIONS

Long-term survival of both PL was high with a low fracture rate. The SS had excellent electrical function but did show higher capture thresholds and increased energy to pace; these differences are offset by other advantages of the SS PL.

Atrioventricular Nodal Reentrant Tachycardia in Patients With Congenital Heart Disease

Background—

The relationship of atrioventricular nodal reentrant tachycardia to congenital heart disease (CHD) and the outcome of catheter ablation in this population have not been studied adequately.

Methods and Results—

A multicenter retrospective study was performed on patients with CHD who had atrioventricular nodal reentrant tachycardia and were treated with catheter ablation. There were 109 patients (61 women), aged 22.1±13.4 years. The majority, 86 of 109 (79%), had CHD resulting in right heart pressure or volume overload. Patients were divided into 2 groups: group A (n=51) with complex CHD and group B (n=58) with simple CHD. There were no significant differences between groups in patients’ growth parameters, use of 3-dimensional imaging, and type of ablation (radiofrequency versus cryoablation). Procedure times (251±117 versus 174±94 minutes; P =0.0006) and fluoroscopy times (median 20.8 versus 16.6 minutes; P =0.037) were longer in group A versus group B. There were significant differences between groups in the acute success of ablation (82% versus 97%; P =0.04), risk of atrioventricular block (14 versus 0%; P =0.004), and need for chronic pacing (10% versus 0%; P =0.008). There was no permanent atrioventricular block in patients who underwent cryoablation. After 3.2±2.7 years of follow-up, long-term success was 86% in group A and 100% in group B ( P =0.004).

Conclusions—

Atrioventricular nodal reentrant tachycardia can complicate the course of patients with CHD. This study demonstrates that the outcome of catheter ablation is favorable in patients with simple CHD. Patients with complex CHD have increased risk of procedural failure and atrioventricular block.

Magnetocardiography-guided management of an unusual case of isoimmune complete atrioventricular block complicated by ventricular tachycardia

A fetus who was diagnosed at 25 weeks of gestation with isoimmune AV block presented at 34 weeks with a precipitous fall in ventricular rate and periods of tachycardia. Magnetocardiography revealed the tachycardia to be ventricular. After delivery, nonsustained ventricular tachycardia continued. The baby then successfully paced, and at higher ventricular rates the tachycardia resolved. Five years later the child has normal ventricular function and is doing well.

Acute sirolimus pulmonary toxicity in an infant heart transplant recipient: case report and literature review

Sirolimus-associated pulmonary disease should be considered in the differential diagnosis of acute respiratory distress syndrome in transplant recipients receiving this drug. It represents a rare, potentially lethal, and yet reversible adverse effect. We report the case an infant who presented with acute respiratory distress 57 days after heart transplantation 3 days after starting sirolimus. The acute presentation and prompt resolution after discontinuation of this drug suggest a direct toxic effect to the lungs. To our knowledge, this is the first published pediatric description of this syndrome after heart transplantation.

Cardiac Transplantation for Pediatric Giant Cell Myocarditis

Giant cell myocarditis (GCM) is an organ-specific, autoimmune disease that infrequently affects children and generally has a more aggressive (often fatal) course than other forms of myocarditis. No data are available about the epidemiology of GCM in children. We describe a 13-year-old girl who presented with ventricular tachycardia and rapid hemodynamic deterioration that required extracorporeal membrane oxygenation (ECMO) as a bridge to heart transplantation. Histopathologic examination of the explanted heart revealed GCM. We review the demographic features, clinical course and post-transplant immunosuppressive therapy of all patients aged 19 years and younger reported to have had GCM.

Comparison of anatomic isthmus block with the modified right atrial maze procedure for late atrial tachycardia in Fontan patients

BACKGROUND

Late atrial reentry tachycardia (AT) after Fontan repair is common, with limited efficacy of medical therapy in preventing AT recurrence. In this study, two approaches to surgical arrhythmia ablation in patients with refractory AT undergoing Fontan revision are compared: cryoablation of the inferomedial right atrium (RA), and a more extensive modified RA maze procedure designed to eliminate all potential RA reentrant circuits.

METHODS AND RESULTS

Fontan revision was performed in 23 patients with AT, using inferomedial RA cryoablation (Group 1, n=8) and modified RA maze procedure (Group 2, n=15). There was no difference in age at initial Fontan, age at Fontan revision, age at onset of AT, or number of failed antiarrhythmic medications. Patients underwent preoperative, intraoperative, and postoperative electrophysiological studies. Thirty-eight different tachycardia circuits were induced in preoperative studies with 3 major areas of RA involvement: the lower lateral RA, the atrial septum, and the inferomedial RA. At postoperative electrophysiological study, AT was inducible in 62% of Group 1 patients but only 7% of Group 2 patients (P<0.02). With mean follow-up of 43 months, 5 of 8 patients in Group 1 experienced AT recurrence compared with none in Group 2 (P<0.001). There was no significant difference in length of hospital stay or complication rate comparing the two groups.

CONCLUSION

Modified RA maze procedure is superior to anatomic isthmus block in treating reentrant AT in postoperative Fontan patients. The modified RA maze has eliminated AT recurrence at mid-term follow-up with low morbidity and mortality.

Total cavopulmonary conversion and maze procedure for patients with failure of the Fontan operation

OBJECTIVES

Hemodynamic abnormalities and refractory atrial arrhythmias in patients late after the Fontan operation result in significant morbidity and mortality. We review our experience with conversion to total cavopulmonary artery connections and arrhythmia surgery.

METHODS

Between 1994 and 2001, 40 patients underwent Fontan conversion and arrhythmia surgery. Significant hemodynamic lesions such as aortic aneurysm (n = 1), atrioventricular valve insufficiency (n = 8), and pulmonary arterioplasty (n = 9) were repaired concomitantly. Thirty-four patients were in New York Heart Association class III or IV. Mean age at the original Fontan operation was 7.5 +/- 6.5 years and mean age at Fontan conversion was 18.7 +/- 9.0 years. Arrhythmia surgery has evolved from isthmus cryoablation in 10 patients to right-sided maze in 16 patients for atrial reentry tachycardia. The maze-Cox III operation was used for 14 patients with atrial fibrillation. Atrial (n = 33) and dual-chamber (n = 5) pacemakers were placed.

RESULTS

There has been no early mortality. Chest tubes were removed on postoperative day 9.0 +/- 6.0. Hospital stay was 11.8 +/- 6.6 days. Three patients required cardiac transplantation at 8 days, 9 months, and 33 months postoperatively. There was 1 death 2 years postoperatively from acute myocardial infarction. For the entire series, arrhythmia recurrence is 12.5%, with only 10% of patients receiving long-term antiarrhythmic medications; these patients were among the first 8 patients in our series. Most patients are in New York Heart Association class I or II. Bruce protocol in 12 patients showed increased tolerance (P <.05).

CONCLUSIONS

Fontan conversion to total cavopulmonary connection with concomitant arrhythmia surgery is excellent therapy for patients whose Fontan repair has failed. Fontan conversion is safe, improves New York Heart Association class, improves exercise tolerance, and has a low incidence of recurrent arrhythmias.