Non-sustained microvolt level T-wave alternans in congenital long QT syndrome types 1 and 2.

BACKGROUND: Patients with long QT syndrome (LQTS) are predisposed to polymorphic ventricular tachycardia (VT) during adrenergic stimulation. Microvolt T-wave alternans (MTWA) is linked to vulnerability to VT in structural heart disease. The prevalence of non-sustained MTWA (NS-MTWA) in LQTS is unknown. METHODS: 31 LQT1, 42 LQT2, and 80 controls underwent MTWA testing during exercise. MTWA tests were classified per standardized criteria, and re-analyzed according to the modified criteria to account for NS-MTWA. RESULTS: LQT1 and LQT2 patients had a significantly higher frequency of late NS-MTWA (26% and 12%) compared to controls (0%). There was no significant difference between the groups with respect to sustained and early NS-MTWA. Late NS-MTWA was significantly associated with QTc. CONCLUSION: LQT1 and LQT2 patients had a higher prevalence of late NS-MTWA during exercise than matched controls. NS-MTWA likely reflects transient adrenergically mediated dispersion of repolarization, and could be a marker of arrhythmic risk in LQTS.

Radiofrequency ablation of fast ventricular tachycardia causing an ICD storm in an infant with hypertrophic cardiomyopathy.

An implantable cardioverter defibrillator (ICD) storm involves very frequent arrhythmia episodes and ICD shocks, and it is associated with poor short-term and long-term prognosis. Radiofrequency catheter ablation can be used as an effective rescue treatment for patients with an ICD storm. To our knowledge, this is the first report of an infant with hypertrophic cardiomyopathy presenting with an ICD storm and undergoing successful radiofrequency catheter ablation salvage treatment for the fast left posterior fascicular ventricular tachycardia.

Video-Assisted Thoracoscopic Left Cardiac Sympathetic Denervation in Patients with Hereditary Ventricular Arrhythmias.

BACKGROUND: Left cardiac sympathetic denervation (LCSD) has been underutilized in patients with hereditary ventricular arrhythmia syndromes such as congenital long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). The purpose of this study was to investigate the safety and efficacy of video-assisted thoracoscopic (VATS) LCSD in such patients. METHODS: Fifteen patients (four men, 24.6 ± 10.5 years old) who underwent VATS-LCSD between November 2010 and January 2015 for hereditary ventricular arrhythmia syndromes at Kyungpook National University Hospital were enrolled in this study. The safety and efficacy of VATS-LCSD were evaluated by periprocedural epinephrine tests and assessing the development of complications and cardiac events during follow-up. RESULTS: Fourteen patients with LQTS and one patient with CPVT underwent VATS-LCSD. Six and one patients developed ventricular tachyarrhythmia during preprocedural and postprocedural epinephrine test, respectively (P = 0.063). No serious complications such as Horner syndrome, pneumothorax, or bleeding developed after LCSD. Mean hospital stay after VATS-LCSD was 3.7 ± 1.5 days. During a mean follow-up of 927 ± 350 days, one LQTS patient and one CPVT patient, neither of whom manifested tachyarrhythmia during post-LCSD epinephrine test, developed torsades de pointes and syncope, respectively. The annual event rates of six patients who were symptomatic during the period preceding LCSD decreased from 0.97 to 0.19 events/year (P = 0.045). CONCLUSIONS: VATS-LCSD was a safe, and effective procedure for patients with hereditary ventricular tachycardia syndrome, with no serious adverse events and with short hospital stay.

Surgical cardiac denervation therapy for treatment of congenital ion channelopathies in pediatric patients: a contemporary, single institutional experience.

BACKGROUND: Congenital ion channel disorders, including congenital long QT syndrome (LQTS), cause significant morbidity in pediatric patients. When medication therapy does not control symptoms or arrhythmias, more invasive treatment strategies may be necessary. This study examines our institution's clinical experience with surgical cardiac denervation therapy for management of these arrhythmogenic disorders in children. METHODS: An institutional review board-approved retrospective review identified ten pediatric patients with congenital ion channelopathies who underwent surgical cardiac denervation therapy at a single institution between May 2011 and April 2014. Eight patients had a diagnosis of congenital LQTS, two patients were diagnosed with catecholaminergic polymorphic ventricular tachycardia (CPVT). All patients underwent sympathectomy and partial stellate ganglionectomy via video-assisted thoracoscopic surgery (VATS). RESULTS: Six of the ten patients had documented ventricular arrhythmias preoperatively, and 70% of the patients had preoperative syncope. The corrected QT interval decreased in 75% of patients with LQTS following sympathectomy. Postoperative arrhythmogenic symptoms were absent in 88% of congenital LQTS patients, but both patients with CPVT continued to have symptoms throughout the duration of follow-up. All patients were alive after a median follow-up period of 10 months. CONCLUSIONS: Surgical cardiac denervation therapy via VATS is a useful treatment strategy for congenital LQTS patients who fail medical management, and its potential benefit in the management of CPVT is unclear. A prospective comparison of the efficacy of surgical cardiac denervation therapy and implantable cardioverter-defibrillator use in congenital ion channelopathies is timely and crucial.

Multivalvular Replacement and Ventricular Arrhythmias in a Female Child With Congenital Polyvalvular Disease.

We report the clinical course of a female child with a normal karyotype and chromosomal microarray who presented as an infant with clinical findings consistent with congenital polyvalvular disease (CPVD). This clinical entity describes patients with multiple congenitally dysplastic valves, often showing nodular or cystic malformation in at least two cardiac valves. This patient then developed medically refractory multifocal ventricular arrhythmia and required radiofrequency ablation at seven months of age. She had good tachycardia control but became symptomatic with right heart failure related to progressive tricuspid, pulmonary, and mitral valve dysfunction necessitating multivalvular replacement at 21 months of age.

[Catecholaminergic polymorphic ventricular tachycardia is a rare inherited heart disease]. / Katekolaminerg polymorf ventrikulaer takykardi er en sjaelden arvelig hjertesygdom.

Catecholaminergic polymorphic ventricular tachycardia is a rare inherited heart disease, which can lead to life-threatening ventricular arrhythmias in patients with a structurally normal heart. The age of onset is usually between two and 12 years and the initial symptom is frequently syncope or cardiac arrest. The arrhythmias are usually triggered by exercise or emotional affection. The diagnosis is often made using exercise electrocardiogram, which typically triggers arrhythmias. The treatment consists of beta blockers, frequently in combination with implantation of a cardioverter-defibrillator.

Neonatal ventricular tachyarrhythmias in medium chain acyl-CoA dehydrogenase deficiency.

We describe an unusually severe case of medium chain acyl-CoA dehydrogenase (MCAD) deficiency in a term female neonate, who presented at 12 h of age with lethargy, poor feeding, hypoglycemia and ventricular tachyarrhythmias. While arrhythmias are common in other disorders of fatty acid beta-oxidation, ventricular tachyarrhythmias have rarely been reported with MCAD deficiency in childhood. Since the results of newborn metabolic screening are usually not available within the first 3 days of life, our case highlights the need for health care professionals to be made aware of this early and uncommon but potentially fatal presentation of MCAD deficiency.

Anesthesia for videoscopic left cardiac sympathetic denervation in children with congenital long QT syndrome and catecholaminergic polymorphic ventricular tachycardia--a case series.

OBJECTIVE: To describe our experience in the anesthetic management of pediatric patients who have undergone left cardiac sympathetic denervation (LCSD) for congenital long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). BACKGROUND: Long QT syndrome and CPVT predispose patients to ventricular arrhythmias and sudden death. One treatment option for these patients is LCSD. When these patients present for LCSD or other surgical procedures, anesthetic management is challenging, as many medications may exacerbate QT prolongation. METHODS: Retrospective review of the electronic medical records of 22 pediatric patients who underwent LCSD between November 2005 and December 2008. RESULTS: Six patients (27%) received midazolam as a premedication. Eleven patients (50%) underwent inhalation induction with sevoflurane. Eighty-six percentage received either sevoflurane or isoflurane for maintenance of anesthesia, while the remaining 14% received a propofol infusion. Nine patients (41%) received esmolol infusions intraoperatively, while one patient (4.5%) received a labetalol infusion. Three patients (14%) received lidocaine infusions. no significant cardiac or other events occurred in any of these patients in the perioperative period. CONCLUSIONS: Important anesthetic considerations in this population include avoidance of sympathetic stimulation, correction of any abnormal electrolytes, and the immediate availability of a defibrillator and magnesium sulfate to treat arrhythmias. Anxious patients may benefit from premedication to reduce sympathetic tone. We have safely used both volatile agents and propofol for induction and maintenance of anesthesia. In our experience, intraoperative infusions of beta-blockers and lidocaine seem to be helpful in reducing arrhythmogenic potential, especially in patients with profound QT prolongation.

Dynamic right ventricular outflow tract (infundibular) stenosis and pectus excavatum in a dog.

This is the first published report of a dog with dynamic right ventricular outflow tract (infundibular) stenosis, right ventricular hypertrophy, and pectus excavatum. A juvenile dog presented with a grade V/VI left base systolic heart murmur, tachycardia, and pectus excavatum. Diagnosis of the aforementioned conditions was based on radiography, electrocardiography, and echocardiography. At 9 1/2 wk of age the heart murmur was no longer audible and the right ventricular stenosis and hypertrophy had dissipated and regressed, respectively. Resolution may be associated with growth of the dog. A good prognosis is foreseen.

Association of congenital, diffuse electrical disease in children with normal heart: sick sinus syndrome, intraventricular conduction block, and monomorphic ventricular tachycardia.

INTRODUCTION: Rhythm disturbances in children with structurally normal hearts are usually associated with abnormalities in cardiac ion channels. The phenotypic expression of these abnormalities ("channelopathies") includes: long and short QT syndromes, Brugada syndrome, congenital sick sinus syndrome, catecholaminergic polymorphic ventricular tachycardia, Lènegre-Lev disease, and/or different degrees of cardiac conduction disease. METHODS: The study group consisted of three male patients with sick sinus syndrome, intraventricular conduction disease, and monomorphic sustained ventricular tachycardia. Clinical data and results of electrocardiography, Holter monitoring, electrophysiology, and echocardiography are described. RESULTS: In all patients, the ECG during sinus rhythm showed right bundle branch block and long QT intervals. First-degree AV block was documented in two subjects, and J point elevation in one. A pacemaker was implanted in all cases due to symptomatic bradycardia (sick sinus syndrome). Atrial tachyarryhthmias were observed in two patients. The common characteristic ventricular arrhythmia was a monomorphic sustained ventricular tachycardia, inducible with ventricular stimulation and sensitive to lidocaine. In one patient, radiofrequency catheter ablation was successfully performed. No structural abnormalities were found in echocardiography in the study group. CONCLUSION: Common clinical and ECG features suggest a common pathophysiology in this group of patients with congenital severe electrical disease.

Calcium channel blockers and beta-blockers versus beta-blockers alone for preventing exercise-induced arrhythmias in catecholaminergic polymorphic ventricular tachycardia.

BACKGROUND: The mainstay of therapy for catecholaminergic polymorphic ventricular tachycardia (CPVT) is maximal doses of beta-blockers. However, although beta-blockers prevent exercise-induced ventricular tachycardia (VT), most patients continue to have ventricular ectopy during exercise, and some studies report high mortality rates despite beta-blockade. OBJECTIVE: The purpose of this study was to investigate whether combining a calcium channel blocker with beta-blockers would prevent ventricular arrhythmias during exercise better than beta-blockers alone since the mutations causing CPVT lead to intracellular calcium overload. METHODS: Five patients with CPVT and one with polymorphic VT (PVT) and hypertrophic cardiomyopathy who had exercise-induced ventricular ectopy despite beta-blocker therapy were studied. Symptom-limited exercise was first performed during maximal beta-blocker therapy and repeated after addition of oral verapamil. RESULTS: When comparing exercise during beta-blockers with exercise during beta-blockers + verapamil, exercise-induced arrhythmias were reduced: (1) Three patients had nonsustained VT on beta-blockers, and none of them had VT on combination therapy. (2) The number of ventricular ectopics during the whole exercise test went down from 78 +/- 59 beats to 6 +/- 8 beats; the ratio of ventricular ectopic to sinus beats during the 10-second period recorded at the time of the worst ventricular arrhythmia went down from 0.9 +/- 0.4 to 0.2 +/- 0.2. One patient with recurrent spontaneous VT leading to multiple shocks from her implanted cardioverter-defibrillator (ICD) despite maximal beta-blocker therapy (14 ICD shocks over 6 months while on beta-blockers) has remained free of arrhythmias (for 7 months) since the addition of verapamil therapy. CONCLUSIONS: This preliminary evidence suggests that beta-blockers and calcium blockers could be better than beta-blockers alone for preventing exercise-induced arrhythmias in CPVT.

Ventricular tachycardia secondary to prolongation of the QT interval in a fetus with autoimmune mediated congenital complete heart block.

We report a case where fetal echocardiography identified both complete heart block and ventricular tachycardia. The mother tested positive for anti-Ro antibodies. Prenatal detection of this unusual combination of arrhythmias prompted early postnatal evaluation, which revealed prolongation of the QT interval. Autoimmune mediated congenitally complete heart block associated with such prolongation of the QT interval has a poor prognosis. The child was successfully treated with beta blockers and implantation of a pacemaker.

Complete elimination of incessant polymorphic ventricular tachycardia in an infant with MIDAS syndrome: use of endocardial mapping and radiofrequency catheter ablation.

Experience with radiofrequency catheter ablation of ventricular tachycardia (VT) in pediatric patients is limited. A 5-month-old white female infant (body weight 5.5 kg) with MIDAS syndrome who suffered from incessant polymorphic VT (ventricular rates 250 to 300 beats/min) and was unresponsive to medical treatment resulting in significantly depressed left ventricular (LV) function underwent a total of four catheter ablation procedures during a 5-month period. Each of the procedures reduced the number of morphologies and the rate of the tachycardia, but VT returned after each of the first three procedures, despite concomitant medical therapy. Activation mapping and pace mapping were used to identify the anatomic substrates, which were found at different locations at the LV septum and LV free wall. All forms of VT finally were ablated successfully. There were no significant complications. After the fourth procedure, the patient was in continuous sinus rhythm. Follow-up examination 29 months after the last procedure while the child was not taking any medication showed normal sinus rhythm and normal LV function. This report demonstrates the usefulness and safety of radiofrequency catheter ablation in an infant with polymorphic VT who was unresponsive to medical therapy.

[Idiopathic left ventricular tachycardia in infancy: long-term control with verapamil]. / Taquicardia ventricular izquierda idiopática en la infancia: control a largo plazo con verapamilo.

Idiopathic verapamil-responsive left ventricular tachycardia is an uncommon arrhythmia in childhood. Although this tachycardia is usually responsive to verapamil, non-pharmacologic therapy may be necessary in the long-term follow-up. We report a thirty-four month old child with incessant left ventricular tachycardia refractory to digoxin and amiodarone. The diagnosis was confirmed by electrophysiologic study. Intravenous verapamil successfully controlled the arrhythmia. On oral verapamil, the patient remains asymptomatic over a follow up period of 7 years and 10 months.

[Sinus node dysfunction in children without heart defect]. / Sinusknotendysfunktion bei Kindern ohne Herzfehler.

Sinus node dysfunction (SND) is a rare cause of bradycardia in children without structural heart disease. The clinical and diagnostic findings in 4 children with this condition are described. Two of them presented with symptoms, in one arrhythmias had been noted before birth, and a routine physical examination had revealed bradycardia in another. Age at onset of either clinical symptoms or bradycardia ranged from 0 to 11 1/2 years. Routine and 24-h-electrocardiograms showed atrioventricular junctional rhythms with minimal rates of 25/min and episodes of asystole with a maximal duration of 10.3 s. Other electrocardiographic abnormalities such as first degree atrioventricular block, ventricular extrasystoles or tachycardia were common findings. Electrophysiological studies were performed in 3 cases and confirmed the diagnosis of SND. A permanent pacemaker was inserted in 2 children; medical treatment did not have any long-term effect. During a follow-up period of 5 to 13 years there were no complications. In summary, SND in childhood can be assessed by Holter monitoring with high reliability. Electrophysiological studies are not necessary and of limited value. Therapeutic policies and prognostic statements are difficult to establish due to the small number of cases so far described. Permanent cardiac pacing, however, is unavoidable in symptomatic children.