Improved Exercise Tolerance in an Adolescent Female After Failed Fontan and Subsequent Biventricular Conversion.

We report a case of improved exercise tolerance in a single-ventricle patient following biventricular conversion. An 11 year old with a fenestrated extracardiac failing Fontan was accepted for a biventricular conversion repair at an out-of-town institution. The patient had multiple adverse cardiac events following Fontan surgery including recurrent pleural effusions, arteriovenous malformations, protein-losing enteropathy, and marked exercise intolerance. Serial cardiac catheterizations revealed chronic elevated pulmonary artery and Fontan pressures, normal left ventricular end-diastolic pressure and an adequately sized left ventricle. Cardiopulmonary exercise testing demonstrated severely reduced exercise tolerance due to ventilatory and cardiac limitations with significant arterial desaturations during exercise. Following a successful biventricular conversion, exercise tolerance improved remarkably, as evidenced by improved oxygen uptake and ventilatory efficiency. Our case demonstrates that biventricular conversion surgery may offer improvement in quality of life and exercise capacity in selected patients with failing Fontan physiology.

Feasibility of P wave Centric Ambulatory Electrocardiogram Monitoring in Infants and Young Children.

P wave centric ambulatory electrocardiographic (ECG) monitoring has emerged as an important tool aiding the diagnosis of arrhythmias. However, their efficacy and user experience in infants and young children are not well established. A retrospective study was performed to detail clinical and user experience of ECG monitoring using the Carnation Ambulatory Monitor (CAM) patch (Bardy Diagnostics Inc., Seattle, WA) in patients less than 10 kg. Additionally, 2 different monitor locations (over the sternum and horizontal over the left axilla) were assessed to address the optimal placement in these patients. A total of 33 CAM reports from 25 patients, aged 0 to15 months were included in the study. Mean patient age was 4.2 months ± 5.0 and mean weight was 5.3 kg ± 2.4. Thirty-six percent of patients (9/25) had known congenital heart disease. Indications for monitoring included: tachyarrhythmia (15/33, 45%), bradyarrhythmia (6/33, 18%), ectopic rhythm (9/33, 27%), cardiac tumor (1/33, 1%), and prolonged QT interval (1/33, 1%). All CAM reports showed clear, identifiable P waves which were diagnostic and lead to changes in medical management for 30% of patients (e.g., medication adjustments or discharge from cardiology care). We found the upright placement over the sternum performed better than the horizontal placement over the left axilla for small infants and children less than 10 kg. A P wave centric single-lead ECG monitor is helpful in providing accurate diagnostics tracings in infants and small children aiding in their clinical management.

Resting electrocardiographic differences in ventricular repolarization between children and young adults with congenital heart disease and those with a structurally normal heart are diminished by exercise.

OBJECTIVE: Exercise-induced repolarization changes have not been systematically evaluated in children and young adults with congenital heart disease (CHD). We carried out this study to assess the QTc responses during exercise in children and young adults (≤ 21 years) with CHD with comparison to those with structurally normal hearts. METHODS: Baseline QRS duration, calculated baseline QTc, QTc at 4 min of recovery and delta QTc was measured in 360 exercise stress tests which were performed in 360 subjects (137 stress tests in patients with CHD [CHD group] and 223 stress tests in patients with structurally normal hearts). The effects of presence of CHD and potential confounders on primary outcome measure, change in QTc (delta QTc), and secondary outcome measures (QTc at baseline and QTc at 4 min of recovery) were determined using multiple linear regression analyses. RESULTS: The baseline QTc and the QTc at 4 min of recovery in the CHD group was longer than patients with structurally normal hearts (respective p values = .00 and .001). No significant difference was noted in delta QTc between the CHD and structurally normal heart groups. CONCLUSIONS: While patients with CHD had a longer QRS duration and QTc interval at baseline than those with structurally normal hearts, these differences did not persist or augment with exercise.

QT Prolongation After Minor Head Trauma in a Pediatric Patient.

We report a case of QTc prolongation associated with mild concussion in a pediatric patient. An 11-year-old male presented to the emergency department after sustaining a head injury during football practice. He complained of headache and blurry vision. Physical examination was within normal apart from an irregular heart rhythm. Electrocardiogram (ECG) showed normal sinus rhythm with QTc (Bazett formula) 460 ms. The patient was diagnosed with concussion and referred for cardiology follow-up of the QTc. ECG the next day showed QTc 462 ms (heart rate 105 bpm) supine and 494 ms after suddenly standing up (heart rate 120 bpm). Family history was negative for sudden cardiac events. Exercise stress testing 1 week later showed a baseline QTc 462 ms and 488 ms at 4 min into recovery. Holter monitoring showed evidence of increased parasympathetic activity manifested by marked sinus arrhythmia. Repeated ECG, exercise stress testing, and Holter monitoring 3 months later showed normalized QTc values. His concussion symptoms were resolved at the time of repeat testing. Mild head trauma/concussion could be associated with prolonged QTc and abnormal cardiac repolarization. While these changes seem to be self-limiting, they remain a possible substrate for malignant arrhythmias. Recognition of these changes would lead to appropriate reassurance and/or precautions in the acute setting, especially in at-risk populations such as long QT syndrome patients.