Philip L. Wackel

Sudden cardiac death and late arrhythmias after the Fontan operation.

OBJECTIVES We sought to examine the incidence and predictors of arrhythmias and sudden cardiac death (SCD) after Fontan operation. BACKGROUND Arrhythmias and SCD have been reported following operations for congenital heart disease, but the incidence and risk factors have not been well defined in patients after a Fontan operation. METHODS We reviewed records of all patients who had a Fontan operation from 1973 to 2012 (n = 1052) at our institution. A questionnaire was mailed to patients who were not known to be deceased at the initiation of the study. Late arrhythmias were classified as bradyarrhythmias or tachyarrhythmias requiring treatment >30 days after operation. RESULTS We included 996/1052 (95%) patients with no arrhythmia diagnosis prior to Fontan. Overall 10-, 20-, and 30-year freedom from arrhythmias was 71%, 42%, and 24%, respectively. Of 864 patients who survived >30 days after Fontan, 304 (35%) had atrial flutter, 161 (19%) had atrial fibrillation, 108 (13%) had atrial tachycardia, 37 (4%) had reentrant supraventricular tachycardia, 40 (5%) had ventricular tachycardia, and 113 (13%) had sinus node dysfunction. Predictors of late arrhythmias included an atriopulmonary Fontan, age at operation (>16 years) or atrial arrhythmias postoperatively. During follow-up, 52/1052 (5%) patients had SCD, with 51 having documentation available; 8 patients died suddenly within 30 days and the remaining 43 had an average time to SCD of 6.9 ± 6.7 years (median was 3.8 years). Arrhythmias were documented in 28/43 (65%) patients prior to SCD. Predictors of SCD included atrioventricular valve replacement and post-bypass Fontan pressures >20 mm Hg; preoperative sinus rhythm was protective. CONCLUSIONS Arrhythmias and SCD are significant concerns among Fontan patients and specific risk factors may warrant closer follow-up and earlier consideration for therapy.

Minimally invasive epicardial implantable cardioverter-defibrillator placement for infants and children: An effective alternative to the transvenous approach

BACKGROUND Young patients have high rates of implantable cardioverter-defibrillator (ICD) lead fractures and are at risk for venous occlusion or tricuspid regurgitation with transvenous lead placement. Epicardial ICDs have the potential to circumvent complications associated with transvenous ICDs, but the literature on young patients remains limited. OBJECTIVE The purpose of this study was to evaluate the results of a minimally invasive epicardial ICD lead placement approach in young patients. METHODS A retrospective, institutional review board-approved electronic medical record review of all patients undergoing epicardial ICD placement at our institution from January 2011 to December 2015 was performed. RESULTS A total of 46 patients (20 female [43%]; mean age 10.3 years, range 0.7-18.2 years; mean weight 41 ± 21 kg) were identified; 24 (52%) were ≤10 years old. A minithoracotomy was used in 28 patients (61%). All had acceptable defibrillation, right ventricular sensing, and stimulation thresholds. Median follow-up was 2.0 ± 1.3 years (range 0.02-4.5 years). Eight surgical complications occurred in 7 patients (15%), and 8 device-related complications occurred in 6 patients (13%). Fifty-eight appropriate shocks were delivered in 7 patients (15%). Four patients received inappropriate shocks in relation to lead fractures/microfractures. One patient in this cohort who had long QT syndrome type 8 died of a hypoglycemic seizure. CONCLUSION Minimally invasive epicardial ICD placement provides an effective, alternative method for implanting an ICD system, particularly in very young patients (<6 years of age) or patients who are concerned about cosmetic appearance. This technique is an acceptable alternative to traditional transvenous ICD placement.

Electrocardiographic abnormalities in elite high school athletes: comparison to adolescent hypertrophic cardiomyopathy

Background In athletes, ECG changes from physiological cardiac remodelling are common but can overlap with findings from a pathological disorder. We compared ECG findings in a group of elite high school athletes to a cohort of adolescents with hypertrophic cardiomyopathy (HCM). Methods/results We prospectively performed 15-lead ECGs and echocardiograms in 147 elite high school athletes. Student-athlete ECGs were compared in blinded fashion to ECGs of 148 adolescents with HCM of similar age and ethnicity. Standard ECG hypertrophy criteria and established expert opinion guidelines (European Society of Cardiology, ESC and Seattle criteria) were analysed. All student-athletes had normal echocardiograms. Overall, 77/147 (52%) of student-athletes met standard ECG criteria for ventricular hypertrophy compared to 126/148 (85%) adolescents with HCM (p<0.0001). There were 112/148 (76%) adolescents with HCM who had pathological Q-waves, T-wave inversion and/or ST-segment depression compared to 1/147 (1%) athletes (p<0.0001). Most patients with HCM (84%, 124/148) had ≥1 abnormal ECG finding(s) according to Seattle criteria, compared to 1% of student-athletes (2/147). Similarly, 130/148 (88%) patients with HCM met group-2 ESC criteria (abnormal), compared to 36/147 (24%) student-athletes (p<0.0001). Conclusions Over 50% of elite high school athletes with echocardiographically confirmed normal hearts satisfied standard voltage criteria for ventricular hypertrophy. Pathological Q-waves, T-wave inversion or ST-segment depression were most helpful in distinguishing adolescents with HCM from normals. Both ESC and Seattle criteria successfully stratified the student-athlete and HCM cohorts, however each had a false-negative rate >10% for the HCM cohort. The Seattle criteria demonstrated a significantly lower false-positive rate (1%) than the ESC criteria (24%).

Selecting the right defibrillator in the younger patient: Transvenous, epicardial or subcutaneous?

The advent of the subcutaneous implantable cardioverter-defibrillator (SQ-ICD) provides an alternative to transvenous and epicardial ICD therapy. Particularly germane to the young patient with congenital heart disease or inheritable arrhythmia syndromes, the SQ-ICD may be ideal for those who do not require permanent cardiac pacing. The serious complications associated with transvenous ICD systems are largely driven by the intravascular components of these devices and are avoided by this extravascular technique. Multiple clinical trials have shown that SQ-ICDs are effective in detecting and terminating ventricular arrhythmias, yet nuanced issues must be considered, especially in the context of congenital cardiovascular anomalies. This review aims to contextualize the role of this technology in contrast with traditional ICDs, and provide a logical approach to appropriate device selection.

Left axis deviation in children without previously known heart disease

Children with incidentally discovered electrocardiographic evidence of LAD and key, identifiable risk factors should be screened for the presence of HD. BACKGROUND: Left axis deviation (LAD) discovered in children via electrocardiogram (ECG) is uncommon but can be associated with heart disease (HD). The optimal diagnostic approach in a seemingly healthy child with LAD is unclear. We sought to better stratify which patients with LAD but without previously known HD may warrant additional workup. METHODS: A retrospective chart review was performed to identify patients ≥1 to <18 years of age with LAD (QRS frontal plane axis 0 to −90) on an ECG between January 2002 and December 2014. Patients with known HD before their initial ECG were excluded. RESULTS: Overall, 296 patients were identified (n = 181 [61%] male; mean age: 10.8 ± 4.6 years; mean QRS axis: −24 ± 22°). An echocardiogram was performed in 158 (53%) patients, with 24 (15%) having HD. Compared with those with an echocardiogram but without HD (n = 134), patients with HD had a more negative mean QRS axis (−42 vs −27°; P = .002) and were more likely to have a QRS axis ≤−42° (58% vs 26%; P = .003), ECG chamber enlargement or hypertrophy (38% vs 5%; P < .0001), and abnormal cardiac physical examination findings (75% vs 8%; P < .0001). CONCLUSIONS: LAD discovered in isolation in the asymptomatic pediatric patient may not necessitate further cardiovascular investigation. Clinicians should consider obtaining an echocardiogram in patients with LAD and ECG cardiac chamber enlargement or hypertrophy, a QRS axis ≤−42°, and/or the presence of abnormal cardiac physical examination findings.

Electrophysiologic Devices in Heart Failure

Abstract With the advent of new technology allowing cardiac devices to be smaller in size, the application of both implantable cardioverter defibrillator (ICD) and pacemaker technology in the pediatric patient with heart failure has expanded. The use of ICDs to decrease the incidence of sudden death and cardiac resynchronization therapy pacemakers have now become an important consideration in the treatment of young patients. Devices can also now also be used to quantify a patients degree of heart failure. Because of the relatively small number of pediatric patients, specific indications are not as well defined as in the adult population. This chapter discusses indications and practical aspects of implantation of pacemakers and ICDs in the pediatric heart failure population.

What is the role of apical ventriculotomy in children and young adults with hypertrophic cardiomyopathy

BACKGROUND The transapical approach has been utilized in adult HCM patients with either midventricular obstruction or a small LV cavity; however, there are little data on its use in children. METHODS We retrospectively reviewed all patients (age <21 years) with HCM who underwent a transapical myectomy from January 2002 to December 2016. Indication for surgery was midventricular obstruction in 19/23 (83%) and small LV cavity in 4 (17%). Preoperative symptoms included: dyspnea (96%), chest pain (65%), presyncope (61%), and syncope (35%). The mean age at the time of operation was 14 ± 4.0 years (range, 4-20). RESULTS Overall, 23 patients (12 males) underwent transapical myectomy. A concomitant transaortic approach was performed in 16/19 (84%) with obstruction. The intraventricular gradient decreased from 71 mm Hg (IQR 44-92 mm Hg) preoperatively to 18 mm Hg (IQR 8-34 mm Hg, P < .0001) after myectomy. In patients with a small LV cavity, the mean left ventricular end diastolic dimension (LVEDD) increased from 40 ± 3 mm to 46 ± 3 mm (P = .05) after myectomy. There were no early deaths. Postoperative morbidity included complete heart block in 3 patients, 2 of which required pacemakers. Median follow up was 3.5 years (IQR 1.6-5.6). Symptoms improved in 95% of patients; the number of patients in NYHA class 3 or 4 heart failure decreased from 10/23 (43%) preoperatively to 3/23 (13%) postoperatively (P < .0001). Overall survival at 5 years postsurgery was 100%. Transplant-free survival was 91% and 87% at 1 and 5 years, respectively. CONCLUSION In children with HCM, transapical myectomy is an effective adjunct to a transaortic approach to abolish midventricular obstruction and it effectively increases LV stroke volume in patients with small LV cavities and nonobstructive HCM. It may be beneficial for these patients with significant symptoms and who have failed medical therapy as a treatment alternative to cardiac transplantation.

Heart Rate and Rhythm Disorders

1. Philip Wackel, MD* 2. Bryan Cannon, MD* 1. *Pediatric Cardiology, Mayo Clinic, Rochester, MN * Abbreviations: AV: : atrioventricular AVR: : accelerated ventricular rhythm ECG: : electrocardiogram PAC: : premature atrial contraction PVC: : premature ventricular contraction QTc: : corrected QT SVT: : supraventricular tachycardia VT: : ventricular tachycardia 1. Proper evaluation of pediatric rhythm disorders can be challenging and requires knowledge of what tests are available and most appropriate to aid in this challenge. (1) 2. Correctly identifying common normal variants in the rhythm and distinguishing them from common abnormal findings is needed to properly triage and treat patients. After completing this article, readers should be able to: 1. Identify by history the symptoms concerning for rhythm disorders. 2. Select appropriate tests in the evaluation of suspected rhythm disorders. 3. Discuss common benign findings and appropriately limit testing/referrals. 4. Describe common rhythm disorders and potential associated underlying problems. Rhythm disorders in pediatric patients encompass a vast and diverse group of problems that vary greatly not only in etiology but also in presentation. These disorders can range from bradycardia to tachycardia but also include inherited channelopathies as well as rhythm disorders associated with underlying congenital heart disease. With such a diverse group of potential problems and the high degree of variability in presenting symptoms, the evaluation and diagnosis of rhythm disorders can be difficult. As with most medical issues, starting with a thorough history and physical examination will help guide the need for further evaluation and testing to reach the appropriate diagnosis. The presentation of arrhythmias varies depending on the type of arrhythmia, but even within the same arrhythmia there can be significant variation in presenting symptoms. Palpitations are a common complaint in the pediatric population, but most patients with palpitations do not have an underlying arrhythmia. Determining which patients …