Thomas Kriebel

Incidence of coronary artery injury immediately after catheter ablation for supraventricular tachycardias in infants and children

BACKGROUND Several case reports have documented coronary artery stenosis or even occlusion after radiofrequency energy ablation (RFA) in children and adults. Coronary involvement early and late after RFA has also been described in animal models. OBJECTIVE The purpose of this study was to assess prospectively the incidence of coronary artery injury early after catheter ablation for supraventricular tachycardias (SVT) in children. METHODS From October 2002 to January 2008, 212 consecutive patients younger than 21 years with SVT underwent selective coronary angiography before and 30 minutes after RFA or cryoablation. RESULTS Median patient age was 12 years (range 0.3-20.4 years), and median body weight was 47 kg (range 5.5-130 kg). An accessory pathway was diagnosed in 112 patients, AV nodal reentrant tachycardia (AVNRT) in 84 patients, and both an accessory pathway and AVNRT in 16 patients. Congenital heart disease was present in 31 patients. In 2 of 117 patients who had RFA for an accessory pathway, an acute reduction in luminal diameter of the coronary artery adjacent to the ablation site was observed. These two patients with a structurally normal heart showed ST-segment changes with normalization of the ECG within 1 week. Both were clinically asymptomatic, and two-dimensional echocardiography documented normal ventricular function. Noninvasive testing did not reveal any evidence of persistent myocardial ischemia. No coronary artery damage was noted after ablation for AVNRT or after ablation with cryoenergy. CONCLUSION Coronary artery narrowing adjacent to the RFA site was noted in 2 of 117 patients with an accessory pathway and occurred only in patients with a posteroseptal pathway. Coronary angiography could be helpful in avoiding coronary lesions in these settings.

Left cardiac sympathetic denervation for the management of life-threatening ventricular tachyarrhythmias in young patients with catecholaminergic polymorphic ventricular tachycardia and long QT syndrome

BackgroundLeft cardiac sympathetic denervation (LCSD) may be a therapeutic adjunct for young patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) and long QT syndrome (LQTS) who are not fully protected by beta-blockade.ObjectiveThe objective of this analysis was to report our institutional experience with LSCD in young patients for the management of life-threatening ventricular arrhythmias in CPVT and LQTS.MethodsTen young patients with CPVT and LQTS underwent transaxillary LSCD at our institution. Mean age at surgery was 14.0 (range 3.9–42) years, mean body weight was 45.7 (range 15.5–90) kg. Five patients had the clinical diagnosis of CPVT, three were genotype positive for a mutation in the ryanodine-receptor-2-gene. Four of five LQTS patients were genotype positive. Indications for LCSD were recurrent syncope, symptomatic episodes of ventricular tachycardias and/or internal cardioverter–defibrillator (ICD) discharges, and aborted cardiac arrest despite high doses of beta-blockers.ResultsLCSD was performed via the transaxillary approach. No significant complications were observed. Two patients already had an ICD, 6 patients received an ICD at the same operation or shortly thereafter. Median length of follow-up after LCSD was 2.3 (range 0.6–3.9) years. After LCSD a marked reduction in arrhythmia burden and cardiac events was observed in all patients while medication was continued. None of the patients had any further ICD discharge for sustained VT.ConclusionsAfter LCSD, arrhythmia burden could significantly be reduced in all our young patients with CPVT and LQTS.

The diagnostic and therapeutic aspects of loss-of-function cardiac sodium channelopathies in children.

BACKGROUND Loss-of-function sodium channelopathies manifest as a spectrum of diseases including Brugada syndrome (BrS) and cardiac conduction disease. OBJECTIVE To analyze the diagnostic and therapeutic aspects of these disorders in children. METHODS Patients aged ≤ 16 years with genetically confirmed loss-of-function sodium channelopathies (SCN5A mutation), presenting with cardiac symptoms, positive family history, and/or abnormal electrocardiogram (ECG), were included. Abnormal ECG consisted of type 1 BrS ECG and/or prolonged conduction intervals (PR interval/QRS duration > 98th percentile for age). RESULTS Among the cohort (n = 33, age 6 ± 5 years, 58% male subjects, 30% probands), 14 (42%) patients were symptomatic, presenting with syncope (n = 5), palpitations (n = 1), supraventricular arrhythmias (n = 3), aborted cardiac arrest (n = 3), and sudden cardiac death (n = 2). Heart rate was 91 ± 26 beats/min, PR interval 168 ± 35 ms, QRS duration 112 ± 20 ms, and heart-rate corrected QT interval 409 ± 26 ms. Conduction intervals were prolonged in 28 (85%) patients; 6 of these patients also had spontaneous type 1 BrS ECG. Eight fever-associated events occurred in 6 patients; 2 of these were vaccination-related fever episodes. Treatment included aggressive antipyretics during fever in all patients; antiarrhythmic treatment included implantable cardioverter-defibrillator (n = 4), pacemaker (n = 2), and beta-blockers, either alone (n = 3) or in combination with device (n = 2). During follow-up (4 ± 4 years), 2 previously symptomatic patients had monomorphic ventricular tachycardia; there were no deaths. CONCLUSIONS Diagnosis of loss-of-function sodium channelopathies in children relies on cardiac symptoms, family history, and ECG. Fever and vaccination are potential arrhythmia triggers; conduction delay is the commonest finding on ECG. Beta-blockers have a role in preventing tachycardia-induced arrhythmias; implantable cardioverter-defibrillator should probably be reserved for severe cases.

Extracorporeal Circulation for Rewarming in Drowning and Near‐Drowning Pediatric Patients

Drowning and near-drowning is often associated with severe hypothermia requiring active core rewarming.We performed rewarming by cardiopulmonary bypass(CPB). Between 1987 and 2007, 13 children (9 boys and 4 girls) with accidental hypothermia were rewarmed by extracorporeal circulation (ECC) in our institution. The average age of the patients was 3.2 years. Resuscitation was started immediately upon the arrival of the rescue team and was continuously performed during the transportation.All patients were intubated and ventilated. Core temperature at admission ranged from 20 to 29°C (mean 25.3°C). Connection to the CPB was performed by thoracic (9 patients) or femoral/iliac means (4 patients). Restoration of circulation was achieved in 11 patients (84.6%). After CPB termination two patients needed an extracorporeal membrane oxygenation system due to severe pulmonary edema.Five patients were discharged from hospital after prolonged hospital stay. During follow-up, two patients died(10 and 15 months, respectively) of pulmonary complications and one patient was lost to follow-up. The two remaining survivors were without neurological deficit.Modes of rewarming, age, sex, rectal temperature, and serum electrolytes did not influence mortality. In conclusion,drowning and near-drowning with severe hypothermia remains a challenging emergency. Rewarming by ECC provides efficient rewarming and full circulatory support.Although nearly half of the children may survive after rewarming by ECC, long-term outcome is limited by pulmonary and neurological complications.

Catheter ablation of idiopathic left and right ventricular tachycardias in the pediatric population using noncontact mapping

BACKGROUND Idiopathic ventricular tachycardia (VT) in children with a structurally normal heart can cause significant morbidity, and although rare, mortality. Conventional activation and pace mapping may be limited by nonsustained tachycardia or unstable hemodynamics. OBJECTIVE The aim of this study was to assess feasibility of catheter ablation of idiopathic VT in the pediatric population guided by noncontact mapping. METHODS Twenty consecutive pediatric patients with idiopathic VT underwent electrophysiologic study with the intention to use the noncontact mapping system EnSite 3000 (EnSite Array, St. Jude Medical Inc., Minneapolis, Minnesota). The multielectrode balloon array was introduced into the left or right ventricle, respectively, and tachycardia was analyzed using color-coded isopotential maps as well as reconstructed unipolar electrograms on the virtual geometry. The region of origin was identified in all of them, and the site of earliest activation with a QS pattern of the unipolar electrograms was guided for sites of ablation. RESULTS Idiopathic VT originated from the right ventricular outflow tract in 6 patients, from the left ventricle in 8, and from the aortic sinus cusp in 6 in this cohort with a median age of 14.4 (range: 4.8 to 20.9) years. Ablation was attempted in 18 of 20 children, and was acutely successful in 17 of these 18 (94%). During a mean follow-up of 2.3 +/- 1.7 years, VT recurred in 3, 2 of them have been treated with a second procedure, resulting in an overall intermediate-term success in 16 of 18 (89%) children with idiopathic VT. CONCLUSION Noncontact mapping can safely and effectively be used to map and guide catheter ablation of the tachycardia substrate of idiopathic VT in pediatric patients.

Immunohistochemical Characterization of Neotissues and Tissue Reactions to Septal Defect–Occlusion Devices

Background—We sought to evaluate tissue reactions within and at the surface of devices for interventional therapy of septal defects and to identify antigen characteristics of neotissues. Methods and Results—Atrial or ventricular septal defect–occlusion devices (Amplatzer, n=7; Cardioseal/Starflex, n=3) were processed using a uniform protocol after surgical removal from humans (implantation time, 5 days to 4 years). Devices were fixed in formalin and embedded in methylmethacrylate. Serial sections were obtained by sectioning with a diamond cutter and grinding, thus saving the metal/tissue interface for histologic evaluation. Immunohistochemical staining was performed using conventional protocols. Superficial endothelial cells stained positive for von Willebrand factor. Within the newly formed tissues, fibroblast-like cells were identified with a time-dependent expression of smooth muscle cell maturation markers (smooth muscle actin, smooth muscle myosin, h-caldesmon, and desmin) beside extracellular matrix components. Neovascularization of the newly formed tissues was demonstrated with the typical immunohistochemical pattern of capillaries and small vessels. Inflammatory cells could be identified as macrophages (CD68+) and both T-type and B-type lymphocytes (CD3+, CD79+). Conclusions—This is the first presentation of results from serial immunohistochemical staining of a collection of explanted human septal-occlusion devices. A time-dependent maturation pattern of the fibroblast-like cells in the neotissues around the implants could be described. Neoendothelialization was seen in all specimens with implantation times of 10 weeks or more. The time course of neoendothelialization, as seen in our study, further supports the clinical practice of anticoagulant or antiplatelet therapy for 6 months after implantation. This time interval should be sufficient to prevent thromboembolic events due to thrombus formation at the foreign surface of cardiovascular implants.

Intraatrial reentrant tachycardias in patients after atrial switch procedures for d-transposition of the great arteries Endocardial mapping and radiofrequency catheter ablation primarily targeting protected areas of atrial tissue within the systemic venous atrium.

13 Patienten mit d-Transposition der großen Arterien nach Vorhofumkehroperation (Mustard/Senning) wurden aufgrund von rezidivierenden intraatrialen Reentry-Tachykardien (IART) elektrophysiologisch untersucht.   Bei 8 Patienten wurden ein 20-poliger Elektrodenkatheter sowie ein 7F steuerbarer Mapping- und Ablationskatheter im system-venösen Vorhof bzw., sofern erforderlich, retrograd im pulmonal-venösen Vorhof platziert. Während der IART wurden Pace- sowie Entrainmentmapping durchgeführt, um geschützte Zonen von Vorhofgewebe zwischen anatomischen und/oder chirurgischen Barrieren elektrischer Isolierung zu lokalisieren. Der system-venöse Vorhof von 5 Patienten wurde mit dem Non-Contact-Mappingsystem (Ensite 3000TM) untersucht.    Nach der Identifikation von elektrisch geschützten Zonen wurden lineare Hochfrequenzstromläsionen bei 4 Patienten von der medialen Seite der oberen Hohlvene zum system-venösen Vorhof und/oder zum intraatrialen Kunststoffflicken bzw. zur intraatrialen Nahtlinie, bei 5 Patienten von der medialen Seite des Mitralklappenannulus zur unteren Hohlvene, bei 1 Patient von der intraatrialen Nahtreihe zum posterioren system-venösen Vorhof und bei 2 Patienten vom posterioren und inferioren pulmonal-venösen Vorhof zum Trikuspidalklappenannulus induziert. Anschließend waren 14 der 15 identifizierten IART während wiederholter programmierter Vorhofstimulation nicht mehr auslösbar. Die Dauer der elektrophysiologischen Untersuchung betrug im Mittel 202 Minuten, die mittlere Durchleuchtungszeit lag im Durchschnitt bei 21,6 Minuten.   Nach einer mittleren Beobachtungszeit von 20 Monaten sind 10 der 12 erfolgreich abladierten Patienten tachykardiefrei, 2 Patienten entwickelten IARTs mit einer neuen Morphologie.    Bei der Mehrheit unserer Patienten konnte eine kurative Therapie mittels Induktion von linearen Hochfrequenzstromläsionen basierend auf der Suche nach elektrisch geschützten Zonen von Vorhofgewebe hauptsächlich im system-venösen Vorhof erzielt werden. Thirteen patients with d-transposition of the great arteries after the Mustard/Senning procedure underwent electrophysiological study for recurrent intraatrial reentrant tachycardia (IARTs). In 8 patients, a 20-pole electrode catheter and a steerable 7F mapping and ablation catheter were placed in the systemic venous atrium, and via the retrograde route in the pulmonary venous atrium, if required. During IART pace mapping and entrainment mapping were performed in order to localize protected areas of atrial tissue between anatomical and/or surgical barriers of electrical isolation. The systemic venous atrium of 5 patients was studied using the non-contact mapping system (Ensite 3000TM).   Linear radiofrequency current lesions were induced after mapping of electrical protected areas from the medial aspect of the superior caval vein to the systemic venous atrium and/or intraatrial baffle or the intraatrial suture line in 4 patients, from the medial aspect of mitral valve annulus to the inferior caval vein in 5 patients, from the intraatrial suture line to the posterior systemic venous atrium in 1 patient and in 2 patients from the posterior and inferior pulmonary venous atrium to the tricuspid valve annulus. Subsequently, 14 of the 15 identified IARTs were not inducible during repeated programmed stimulation. Mean duration of the electrophysiological study was 202 min, mean fluoroscopy time was 21.6 min. During follow-up (mean 20 months), 10 of 12 patients with successful procedures are free of tachycardia, 2 patients developed IARTs with a new morphology.   In the majority of our patients, curative treatment was feasible by induction of linear radiofrequency current lesions by primarily targeting electrical protected areas of atrial tissue in the systemic venous atrium.

Melody transcatheter valve: Histopathology and clinical implications of nine explanted devices

OBJECTIVES We examined interventionally implanted valved Melody conduits after surgical explantation by means of histology and immunohistochemistry and matched these findings with clinical data in order to assess in vivo biocompatibility and to identify risk factors for graft failure. METHODS 9 Melody valves had been implanted in 8 patients (pulmonary n = 7, tricuspid position n = 1). Indication for explantation included significant obstruction in 7 patients and valve insufficiency in 1 patient. 4 of 8 patients had suffered from endocarditis. Mean interval between implantation and explantation was 3.2 (1.8-5.2) years. All explants were worked up using a uniform protocol with fixation in formalin and embedding in methylmethacrylate. RESULTS All but one valve of the explanted Melody grafts were thin and histologically intact without any pathological findings. Complete neo-endothelialization could be demonstrated by means of immunohistochemistry. All 4 Melody valves from patients with endocarditis showed dense granulocytic infiltrations, 3 of these showed thrombotic material within the valves. CONCLUSION This report covers the first series of explanted Melody valves from humans applying a uniform protocol for histopathological examination. Good biocompatibility of the Melody valves could be demonstrated after a mid-term follow-up. Factors for graft failure included endocarditis, outgrowth, and residual stenosis. These findings may have significant implications for the implant procedure as well as care of the patients during long-term follow-up.

A de novo interstitial deletion of 2p23.3–24.3 in a boy presenting with intellectual disability, overgrowth, dysmorphic features, skeletal myopathy, dilated cardiomyopathy†

Interstitial deletions of the distal part of chromosome 2p are rare, with only six reported cases involving regions from 2p23 to 2pter. Most of these were cytogenetic investigations. We describe a 14‐year‐old boy with an 8.97 Mb deletion of 2p23.3–24.3 detected by array comparative genomic hybridization (array CGH) who had intellectual disability (ID), unusual facial features, cryptorchidism, skeletal myopathy, dilated cardiomyopathy (DCM), and postnatal overgrowth (macrocephaly and tall stature). We compared the clinical features of the present case to previously described patients with an interstitial deletion within this chromosomal region and conclude that our patient exhibits a markedly different phenotype. Additional patients are needed to further delineate phenotype–genotype correlations

Value of dynamic substrate mapping to identify the critical diastolic pathway in postoperative ventricular reentrant tachycardias after surgical repair of tetralogy of fallot.

Characterization of the Critical Isthmus in VT in TOF. Introduction: The complexity of postoperative ventricular reentrant tachycardias may limit success of catheter ablation. The objective of this analysis was to compare the usefulness of dynamic substrate mapping (DSM) versus color‐coded isopotential mapping of the noncontact mapping system for the identification of the critical diastolic pathway of postoperative ventricular reentrant tachycardias (VT) after surgical repair of tetralogy of Fallot (TOF).