Low-voltage bridge strategy to guide cryoablation of typical and atypical atrioventricular nodal re-entry tachycardia in children: mid-term outcomes in a large cohort of patients.

AIMS: In the current literature, results of the low-voltage bridge (LVB) ablation strategy for the definitive treatment of atrioventricular nodal re-entry tachycardia (AVNRT) seem to be encouraging also in children. The aims of this study were (i) to prospectively evaluate the mid-term efficacy of LVB ablation in a very large cohort of children with AVNRT, and (ii) to identify electrophysiological factors associated with recurrence. METHODS AND RESULTS: One hundred and eighty-four children (42% male, mean age 13 ± 4 years) with AVNRT underwent transcatheter cryoablation guided by voltage mapping of the Koch's triangle. Acute procedural success was 99.2% in children showing AVNRT inducibility at the electrophysiological study. The overall recurrence rate was 2.7%. The presence of two LVBs, a longer fluoroscopy time and the presence of both typical and atypical AVNRT, were found to be significantly associated with an increased recurrence rate during mid-term follow-up. Conversely, there was no significant association between recurrences and patient's age, type of LVB, lesion length, number of cryolesions or catheter tip size. CONCLUSION: The LVB ablation strategy is very effective in AVNRT treatment in children. Recurrences are related to the complexity of the arrhythmogenic substrate.

Voltage gradient mapping and electrophysiologically guided cryoablation in children with AVNRT.

Aims: Recently, voltage gradient mapping of Koch's triangle to find low-voltage connections, or 'voltage bridges', corresponding to the anatomic position of the slow pathway, has been introduced as a method to ablate atrioventricular nodal reentry tachycardia (AVNRT) in children. Thus, we aimed to assess the effectiveness of voltage mapping of Koch's triangle, combined with the search for the slow potential signal in 'low-voltage bridges', to guide cryoablation of AVNRT in children. Methods and results: From June 2015 to May 2016, 35 consecutive paediatric patients (mean age 12.1 ± 4.5 years) underwent 3D-guided cryoablation of AVNRT at our Institution. Fifteen children were enrolled as control group (mean age 14 ± 4 years). A voltage gradient mapping of Koch's triangle was obtained in all patients, showing low-voltage connections in all children with AVNRT but not in controls. Prior to performing cryoablation, we looked for the typical 'hump and spike' electrogram, generally considered to be representative of slow pathway potential within a low-voltage bridge. In all patients the 'hump and spike' electrogram was found inside bridges of low voltage. Focal or high-density linear lesions, extended or not, were delivered guided by low-voltage bridge visualization. Acute success rate was 100%, and no recurrence was reported at a mean follow-up of 8 ± 3 months. Conclusions: Voltage gradient mapping of Koch's triangle, combined with the search for the slow potential signal in low-voltage bridges, is effective in guiding cryoablation of AVNRT in paediatric patients, with a complete acute success rate and no AVNRT recurrences at mid-term follow-up.

Radiofrequency catheter ablation of left-sided accessory pathways in children using a new fluoroscopy integrated 3D-mapping system.

Introduction: Advances in 3D electroanatomic-mapping technologies have resulted in a safe and effective profile of radiofrequency (RF) catheter ablation. The aim of this study was to evaluate a different catheter ablation approach in patients with left-sided accessory pathways (APs). Methods and results: From January 2015 to December 2015, 30 patients (median age 11 years, median weight 45 kg) with manifest or concealed left-sided APs underwent RF catheter ablation with a new protocol. All procedures were performed with the CARTO UNIVU™ system, integrating electroanatomic maps with fluoroscopic views. A 7 Fr ablation catheter was inserted into the right femoral vein and advanced into the right atrium. Geometrical reconstruction and activation map of the right atrium, tricuspid annulus, and coronary sinus were acquired. The ablation catheter was then inserted into the left femoral artery and advanced through the aorta and aortic valve, creating an activation map of the mitral annulus. Catheter ablation was targeted to the site of the earliest activation. No complications occurred. The median procedure and fluoroscopy times were 130 min and 6 s, with a median fluoroscopy dose 0.5 mGy. An average of two catheters was used. Long-term success rate was 97% (29/30) at a median follow-up of 9.6 months. This approach reduced fluoroscopy time, dose and number of catheters used compared with manifest or concealed left-sided AP ablation using CARTO 3™ (P < 0.05). Conclusions: This new ablation protocol seems to be promising in reducing fluoroscopy exposure and number of catheters used during left-sided AP ablation in children.

Carotid artery intima-media thickness and stiffness index ß changes in normal children: role of age, height and sex.

AIMS: The need for early markers of atherosclerosis in paediatric ages has been emphasized recently. Few data are available on the behaviour of carotid intima-media thickness (cIMT) and arterial stiffness in normal children. METHODS: We studied prospectively 131 healthy children (78 boys), aged 3-16 years, by high-definition ultrasonography and echo-tracking technique in order to evaluate cIMT and stiffness index ß. RESULTS: Stiffness index ß underwent a significant age-related increase (P < 0.001), and a positive relationship between cIMT and height was found in boys. In addition, stiffness index ß and cIMT were not related to each other (P = 0.97). CONCLUSION: This study provides information about two markers of subclinical atherosclerosis, cIMT and carotid stiffness index ß, in normal children aged 3-16 years. We found a significant age-related and height-related increase of stiffness index ß in both sexes, whereas cIMT was positively related to height only in boys.

The Need for a Lengthier Cryolesion Can Predict a Worse Outcome in 3D Cryoablation of AV Nodal Slow Pathway in Children.

BACKGROUND: Transcatheter cryoablation is a well-established technique for the treatment of atrioventricular nodal reentry tachycardia (AVNRT) in children. Nevertheless, atrioventricular nodal slow-pathway conduction may recur after an acutely successful procedure. The aim of this study was to evaluate the long-term outcome of acutely successful AVNRT cryoablations in pediatric patients in case of focal cryolesion and in case of need for High-Density Linear Lesion (HDLL) cryoablation due to focal failure. METHODS: Sixty-nine consecutive pediatric patients (30 males, mean age 12.4 ± 3.2 years; range: 5.4-18.0 years) underwent 3D-guided cryoablation for AVNRT at our institution from July 2013 to November 2014. When a focal cryoablation was acutely unsuccessful, a 3D-guided HDLL was created delivering multiple overlapping cryolesions/cryoenergy applications from the ventricular side of the tricuspid annulus to the atrial side, including the site of focal cryoablation if transiently successful. RESULTS: No permanent cryoablation-related complications occurred. Acute success rate was 98.5% (68 out of 69): in 55.9% (38 out of 68) with focal-lesion and in 44.1% (30 out of 68) with HDLL. Mean follow-up was 25.3 months and AVNRT recurrence rate was 13.2% (nine out of 68): 5.2% (two out of 38) with focal lesion and 23.3% (seven out of 30) with HDLL (P = 0.036). CONCLUSIONS: In cryoablation of AVNRT in children, the need for a more aggressive protocol (HDLL), due to the failure of focal ablation, is strictly related to higher recurrence rates. Indeed, AVNRT recurrences after cryoablation in children seem to be due to a larger and deeper substrate rather than due to the type of energy used.

Role of right ventricular three-dimensional electroanatomic voltage mapping for arrhythmic risk stratification of patients with corrected tetralogy of Fallot or other congenital heart disease involving the right ventricular outflow tract.

BACKGROUND: The post-surgical history of repaired congenital heart disease (rCHD), in particular tetralogy of Fallot (TOF), is often complicated by sudden death. Electrical myocardial abnormalities could be a substrate for malignant ventricular arrhythmias. METHODS AND RESULTS: 146 patients with TOF or other rCHD involving a subpulmonary right ventricle, considered to be at high arrhythmic risk, underwent right ventricular (RV) electroanatomic voltage mapping (EVM). Maps showed endocardial scars (<0.5mV) in all cases, mainly involving the RV outflow tract (n=141, 96.6%). In 28 cases (19.2%), other areas were involved. Total scar extension, expressed as % of total endocardial area, was significantly higher in patients with QRS ≥180ms [4.5% (±2.5) vs 2.8% (±2.4), p=0.014], left and right ventricular systolic dysfunction [4.5% (±3.2) vs 2.8% (±2.3), p=0.016 and 3.5% (±3.0) vs 2.6% (±1.9), p=0.03, respectively], premature ventricular contractions (PVCs) [3.2% (±2.6) vs 2.2% (±1.8), p<0.05], exercise-induced PVCs [3.8% (±2.4) vs 2.6% (±2.2), p=0.01], previous shunt [4.0% (±2.7) vs 2.6% (±2.2), p=0.01] and reintervention [4.2% (±3.2) vs 2.6% (±2.0), p=0.008]. Scar size also showed a positive correlation with duration of post-surgical follow-up (ρ=0.01), age at correction (ρ=0.01) and absolute QRS duration (ρ=0.05). CONCLUSIONS: Patients with rCHD involving the right ventricle show electrical scars with variable distribution, not necessarily matching with sites of surgical lesions. Scar extension correlates with some of the risk factors for life-threatening arrhythmias in CHD, such as prolonged QRS. Thus EVM could be considered an additional tool in the assessment of risk stratification in this particular population.

Miniaturized Implantable Loop Recorder in Small Patients: An Effective Approach to the Evaluation of Subjects at Risk of Sudden Death.

BACKGROUND: The etiological diagnosis of syncope and/or palpitations in children is often challenging. However, when noninvasive conventional examinations are inconclusive, the subcutaneous miniaturized implantable loop recorder (ILR) is recommended. The aim of our study was to evaluate the efficacy of miniaturized cardiac implantable devices in the early diagnosis of arrhythmias in children ≤6 years. METHODS: From March 2014 to May 2015, 21 patients (median age 5 years) underwent implantation of miniaturized ILR at our Institution after a complete cardiac work up. Median follow-up was 10 months. RESULTS: One patient underwent device removal for pocket infection and one needed a pocket revision. Eleven (52%) patients did not show any symptom and/or arrhythmia. Eight patients experienced symptoms during ILR monitoring: six had no electrocardiographic abnormalities, two had significant sinus pauses. Two patients had significant arrhythmias without symptoms and in one of these a pacemaker was implanted. The overall diagnostic yield was 47%. CONCLUSIONS: Miniaturized ILR could be very useful to make a diagnosis and to decide future management strategies in small patients with undefined symptoms or severe cardiac diseases. Considering its characteristics, miniaturized ILR could start a new era in the diagnosis and follow-up of young patients with symptomatic and/or malignant arrhythmias.

Preexcitación ventricular: los niños sintomáticos y asintomáticos tienen el mismo riesgo potencial de muerte cardíaca súbita

Objetivos: los niños y adolescentes con preexcitación ventricular (PV) tienen un mayor riesgo de muerte súbita cardíaca (MSC). Si bien la terapia antiarrítmica y la ablación por catéter son tratamientos temporales o definitivos bien establecidos para los pacientes con síndrome de Wolff-Parkinson-White (WPW), aún no hay acuerdo acerca del manejo óptimo de los niños con PV asintomática. Teniendo en cuenta las directrices y recomendaciones más recientes, el objetivo de este estudio fue determinar las características electrofisiológicas de los pacientes jóvenes con PV y síndrome de WPW, con el fin de valorar y comparar su riesgo potencial de MSC. Métodos y resultados: se realizó un estudio retrospectivo de 124 pacientes jóvenes consecutivos con PV (51 con síndrome de WPW y 73 asintomáticos) sometidos a un estudio electrofisiológico transesofágico. En condiciones basales se indujo una taquicardia por reentrada auriculoventricular (TRAV) en 13 pacientes con WPW vs 10 pacientes asintomáticos (25,5% vs 13,7%, p=NS). Se indujo fibrilación auricular (FA) en 13 pacientes con WPW vs 15 pacientes asintomáticos (25,5% vs 20,5%, p=NS). Se encontró un intervalo R-R preexcitado más corto (IRRPEC o SPERRI, por sus siglas en inglés) £ 250 ms durante la FA en cuatro pacientes con WPW vs seis pacientes asintomáticos (30,8% vs 40%, p=NS). Durante la infusión de isoproterenol o la prueba de esfuerzo, se indujo TRAV en 31 de 44 pacientes con WPW vs 33 de 69 pacientes asintomáticos (70,4% vs 47,8%, p=0,018). Se indujo fibrilación auricular en 12 de 44 pacientes con WPW vs 21 de 69 pacientes asintomáticos (27,3% vs 30,4%, p=NS). Se encontró un IRRPEC £ 210 ms en 6 de 12 pacientes con WPW vs 10 de 21 pacientes asintomáticos (50% vs 476%, p=NS). No se observó ninguna correlación estadísticamente significativa entre la ubicación de la vía accesoria y los síntomas, inducibilidad de TRAV/FA, o media de período refractario de la vía accesoria (PREVA)/IRRPEC. Conclusión: los niños y adolescentes con síndrome de WPW tienen una mayor tasa de inducibilidad de TRAV que los pacientes asintomáticos. Sin embargo, no se encontraron diferencias entre los dos grupos en cuanto a la vulnerabilidad auricular y a los parámetros relacionados con el riesgo de MSC.

First report of image integration of cine-angiography with 3D electro-anatomical mapping of the right ventricle in postoperative tetralogy of Fallot.

Ventricular tachycardia and, more rarely, sudden cardiac death are potential complications affecting the long-term outcome after Tetralogy of Fallot (ToF) repair. Intraventricular septal scar, fibro-fatty substitution around infundibular resection and patchy myocardial fibrosis may provide anatomical substrates of abnormal depolarization and repolarization causing reentrant ventricular arrhythmias. Recently, three-dimensional electro-anatomical mapping (3D EAM) has allowed to investigate the electro-anatomical status of the right ventricle. Radiation exposure during cardiac electrophysiological procedures is still a major concern. We report the first case of 3D mapping of the right ventricle in a postoperative ToF patient performed with a new module of the CARTO® 3 System-the CARTOUnivu™ Module-that combines, simultaneously, fluoroscopic images or cine-angiographic sequences with 3D cardiac mapping to allow real-time visualization of the electrocatheter during the 3D EAM reconstruction. The same volume, previously evaluated with cardiac MRI, was mapped. A perfect match of the diastolic edges of the RV obtained either by cine-loop acquisition during contrast fluoroscopy and by the 3D EAM, was observed. The fluoroscopy time for 3D EAM was 10 s. In conclusion, CARTOUnivu™ Module can integrate, in real time, fluoroscopic images/cine-angiography in virtual biplane view and the 3D EAM allowing a contextual visualization of position and movement of all electrocatheters. This can further increase the accuracy of the 3D EAM in very complex-operated congenital heart diseases, even decreasing radiation exposure.

Ventricular pre-excitation: symptomatic and asymptomatic children have the same potential risk of sudden cardiac death.

AIMS: Children and adolescents with ventricular pre-excitation (VPE) are at increased risk for sudden cardiac death (SCD). Although antiarrhythmic therapy and catheter ablation are well established temporary or definitive treatments for patients with Wolff-Parkinson-White (WPW) syndrome, the optimal management of children with asymptomatic VPE remains to be clearly defined. On the basis of the most recent guidelines and recommendations, the aim of this study was to determine the electrophysiological characteristics of young patients with VPE and WPW syndrome to assess and compare their potential risk of SCD. METHODS AND RESULTS: We retrospectively investigated 124 consecutive young patients with VPE (51 with WPW syndrome and 73 asymptomatic) who underwent transoesophageal electrophysiological study. At baseline, atrioventricular reentrant tachycardia (AVRT) was induced in 13 WPW vs. 10 asymptomatic patients (25.5 vs. 13.7%, P = NS). Atrial fibrillation (AF) was induced in 13 WPW vs. 15 asymptomatic patients (25.5 vs. 20.5%, P = NS). A shortest pre-excited R-R interval (SPERRI) ≤250 ms during AF was found in four WPW vs. six asymptomatic patients (30.8 vs. 40%, P = NS). During isoproterenol infusion or stress testing, AVRT was induced in 31 of 44 WPW vs. 33 of 69 asymptomatic patients (70.4 vs. 47.8%, P = 0.018). Atrial fibrillation was induced in 12 of 44 WPW vs. 21 of 69 asymptomatic patients (27.3 vs. 30.4%, P = NS). A SPERRI ≤ 210 ms was found in 6 of 12 WPW vs. 10 of 21 asymptomatic patients (50 vs. 47.6%, P = NS). No statistically significant correlation was observed between accessory pathway location and symptoms, AVRT/AF inducibility, or mean APERP/SPERRI values. CONCLUSION: Children and adolescents with WPW syndrome have a higher rate of AVRT inducibility than asymptomatic patients. However, no differences between the two groups were found in atrial vulnerability and parameters related to the risk of SCD.

Transient cardiac effects in a child with acute cholinergic syndrome due to rivastigmine poisoning.

BACKGROUND: We report a case of rivastigmine poisoning resulting in a full cholinergic syndrome with nicotinic, muscarinic, and central effects requiring supportive or intensive care in a pediatric patient. CASE REPORT: A 3-year-old girl was admitted to the Emergency Department suspected of having ingested one or two pills of rivastigmine. The child was hyporeactive, with symptoms of altered mental status, sialorrhea, sweating, and diarrhea. Subsequently, she started showing signs of respiratory failure, severe tracheobronchial involvement, and gastric and abdominal distension. An electrocardiogram recorded frequent monomorphic ventricular ectopic beats with bigeminy and trigeminy. Long-term follow-up showed a transient dysrhythmia. CONCLUSION: Poisoning with rivastigmine can be a life-threatening condition. Timely identification and appropriate management of the toxic effects of this drug are essential and often life-saving. This is particularly true in cases of cholinergic syndrome subsequent to drug poisoning. Patients with cholinergic syndrome should also be assessed for possible cardiac complications such as dysrhythmias. The main factors predisposing to the development of such complications are autonomic disorder, hypoxemia, acidosis, and electrolyte imbalance.

Cryoablation of AVNRT in children and adolescents: early intervention leads to a better outcome.

INTRODUCTION: Currently, transcatheter cryoablation is a well-established technique for the treatment of atrioventricular nodal reentry tachycardia (AVNRT) in children. In the past decade, many studies have focused on identifying factors that may affect acute and long-term outcome, but none has been shown to be strongly predictive of treatment success. The aim of our study was to determine whether patient age and cryoablation method correlate with acute and long-term success. METHODS AND RESULTS: We retrospectively reviewed 202 consecutive patients (98 male, mean age 11.5 years; range: 4-20 years) who underwent cryoablation for AVNRT at our institution from October 2002 to August 2012. Patients were divided into 2 groups according to age: group A <12 years (n = 101) and group B ≥12 years (n = 101). A single lesion or linear lesion technique was employed. A total of 217 cryoablation procedures were performed: 106 (49%) in group A and 111 (51%) in group B. All patients were evaluated in our postoperative follow-up program. The overall recurrence rate was 10.9% (22/202). AVNRT recurrence was significantly lower in group A than in group B (4.95% vs 16.8%, P = 0.000). No significant differences in recurrence rate were observed between groups when using the single lesion versus linear lesion technique. There were no permanent cryoablation-related complications. CONCLUSION: Our findings show that cryoablation had no complications and a very good success rate. Type of cryolesion is not predictive of long-term success, whereas lower recurrence rate is achieved when cryoablation is performed at a younger age.

Cryoablation of right-sided accessory pathways in children: report of efficacy and safety after 10-year experience and follow-up.

AIMS: The aim of this study was to report the 10-year experience of our Institution in cryoablation of supraventricular tachycardia due to a right accessory pathway (AP). METHODS AND RESULTS: Seventy-one cryoablations of right AP were performed between July 2002 and October 2011 in our Institution in 66 patients (mean age 12 + 3 years, 56% males). Acute procedural success rate was 97%: 80% in patients with concealed AP and 100% in those with manifest AP (P < 0.05). Acute procedural success rate was not related to institutional experience. No permanent complication occurred. Sixteen patients had recurrences during the follow-up (18.6 ± 6.6 months; range 3-111), 13 within the first month of follow-up, 2 within the 6 months of follow-up, and 1 within 12 months of follow-up. Cox regression showed that sex, patient age, number of delivered cryo-bonus, and presence of manifest or concealed AP are not independent predictors of procedural success. Among the 16 patients with recurrences, in 10 a cryoablation redo was successful and with no further AP recurrences. The mean fluoroscopy time was 28.4 min (range 19.7-44.6) with a significant decrease (P = 0.033) in relation to the increase of the institutional experience. There were no permanent ablation-related complications. CONCLUSION: Cryoablation of right-sided AP is effective and very safe in children. Better results are achieved in manifest AP. The learning curve has a real impact in the attempt to reduce the fluoroscopy time.

Atrial tachycardias in patients with congenital heart disease: a minimally invasive simplified approach in the use of three-dimensional electroanatomic mapping.

AIMS: Atrial tachycardia (AT) is a common complication after repair of congenital heart disease (CHD). This two-centre prospective study evaluated the ability of three-dimensional electroanatomic mapping (EAM) to guide ablation of ATs in this particular population with a minimally invasive simplified approach. METHODS AND RESULTS: Thirty-one consecutive patients (mean age 26 ± 17 years) with AT after repair of CHD were treated with a very limited number of intracavitary catheters and a specific setting of the Window of Interest (WoI) for the ablation of post-surgical ATs. A single-intracavitary catheter approach was performed in 22 patients, whereas an overall use of two intracavitary catheters in the other nine patients. Thirty-one patients exhibited 41 ATs. Seventy-six per cent of these were macro-reentrant ATs (MRATs), and 24% were focal ATs (FAT). The mid-diastolic isthmus (MDI) was located in the right atrial free wall (RAFW) in 82.8% of MRATs. Also in FATs, the RAFW was the most common site (77.8%) of the ectopic focus. Fifty-eight per cent of MRATs showed a double-loop reentry, with both loops sharing the same MDI in all cases. In 87% of cases, the abolition of the MRAT was obtained by applying radiofrequency energy to the MDI. Ninety per cent of FATs were successfully ablated. Mean conduction velocity and voltage amplitude had significantly lower values in successfully treated than in unsuccessfully treated MRATs. CONCLUSION: Three-dimensional EAM, performed with a minimally invasive simplified approach and by using a specific parameter setting of the WoI, showed to be very effective to guide ablation of ATs in CHD patients.

Bifid T waves in leads V2 and V3 in children: a normal variant.

INTRODUCTION: The T wave is rarely bifid, apart from patients with long QT syndrome or subjects treated with antiarrhythmic drugs. At times, a U wave partially superimposed upon the T wave is responsible for an apparently bifid T wave. Bifid T waves, in contrast, have been described in normal children in the past, but the phenomenon has not received any attention in recent years, to the extent that it is not mentioned in current textbooks of paediatric cardiology. Aim of the present study was to determine the incidence and clinical counterpart of bifid T waves in a paediatric population. METHODS: We selected 604 consecutive children free from clinically detectable heart disease; subjects whose electrocardiogram showed a bifid T wave underwent a complete clinical and echocardiographic examination. In addition, the electrocardiograms of 110 consecutive adults have also been analyzed. A T wave was considered as bifid whenever it was notched, being the 2 peaks separated from each other by a notch with duration >/= 0.02 sec and voltage >/= 0.05 mV. Moreover, in 7 children with bifid T wave in lead V2 further precordial recordings were obtained: a small electrode was gradually moved from V1 to V3, and 4 additional leads were recorded: 2 between V1 an V2, and 2 between V2 and V3. RESULTS: A bifid T wave was observed in 110 children (18,3%), with a relatively age-related incidence; the highest rate of bifid T waves (53%) occurred in the group of 5-year-old children. The bifid T wave was detected only in lead V2 in 51 cases (46,4%), only in lead V3 in 5 cases (4,6%), in both leads V2 and V3 in 50 cases (45,4%), and in leads other than V2 and V3 in 4 cases (3,6%). In the adult group, none of the examined electrocardiograms showed bifid T waves in any lead.In the bifid T wave paediatric population, the echocardiogram did not reveal any abnormality, apart from 3 subjects which had an asymptomatic mitral valve prolapse; a trivial mitral and/or tricuspid regurgitation detected by color Doppler, as well as a patent foramen ovale in infants, were not considered as abnormal findings. The QTc interval was normal in all of the subjects; the average QTc interval was not different in the bifid T wave population (402 +/- 46 msec) with respect to the control group (407 +/- 39 msec). CONCLUSION: The incidence of bifid T waves in leads V2 and V3 in normal children is high, and awareness of this phenomenon avoids possible misinterpretations leading to a diagnosis of ECG abnormalities.

'Time to effect' during cryomapping: a parameter related to the long-term success of accessory pathways cryoablation in children.

AIMS: Cryoablation is an effective treatment for children with an accessory pathway (AP). Nevertheless, AP may recur after a successful procedure. The aim of this study was to identify the factors predictive of AP recurrence. METHODS AND RESULTS: Thirty patients (mean age 12.6 +/- 2.9 years) with acutely successful cryoablation of supraventricular tachycardia caused by a right-sided AP were studied. In 20 patients, a lengthier cryoablation and a single 'bonus' cryoapplication to consolidate a permanent lesion were delivered. During the follow-up (mean duration 20 months, range 4-25), no permanent cryo-related complications occurred. Accessory pathway recurrence was observed in six patients (20%) overall, specifically in 30% of patients who did not undergo a bonus cryoapplication and in 15% of the others. The likelihood of AP recurrence was correlated with the 'time to effect' (TTE), i.e. the time interval between the onset of cryomapping at -30 degrees C and the disappearance of AP conduction. The mean TTE in the patients without AP recurrence was 8.2 +/- 8.4 s, in contrast with 16.7 +/- 9.8 s in the others (P = 0.04). The receiver-operating characteristic (ROC) curve of TTE values demonstrates that if the pathway does not lose its conduction capacity until 10 s after reaching -30 degrees C, the probability of arrhythmia recurrence is higher (area under curve = 0.767, sensitivity 83.3%, and specificity 66.7%). CONCLUSION: The long-term success of cryoablation of right-sided AP is closely correlated to the TTE during cryomapping.

[Transcatheter cryoablation in children: state of the art]. / Crioablazione transcatetere in età pediatrica: stato dell'arte.

A new transcatheter ablation method has recently made its appearance in leading electrophysiology laboratories: cryoablation. In contrast with radiofrequency, this method produces a permanent lesion due to cell necrosis, caused by application of very low temperature chilling to the tip of special ablation catheters placed against the area of the heart causing arrhythmia. The benefit of this system over radiofrequency ablation is its ability to find the most suitable site for ablation through transitory electrical paralysis of the heart tissue in contact with the catheter tip, chilled to -30 degrees C (cryomapping). If the site is suitable, the tissue causing the arrhythmia loses its excitability. Moreover, the stability of the catheter tip, which adheres to the myocardium, enables arrhythmia inducibility through programmed atrial stimulation to be assessed without dislodging the catheter. A permanent lesion is created only subsequently, with further chilling to even lower temperatures (cryoablation). In the last 3 years the success rate of cryoablation in pediatric patients has increased and long-term complications have not been described yet. We therefore consider that cryoablation should be considered the treatment of choice for atrioventricular nodal reentrant tachycardia and parahissian, anteroseptal and right midseptal accessory pathway atrioventricular reentrant tachycardia in school-age children. In fact cryoablation is thus "made to measure" for pediatric patients because if an atrioventricular block is observed, stopping the procedure is quickly followed by the restoration of normal atrioventricular conduction.

Hypertrophic cardiomyopathy mimicking acute myocardial infarction: diagnostic role of cardiac magnetic resonance.

Rarely, hypertrophic cardiomyopathy can be associated with ST elevation on electrocardiogram. We report a rare case of anterior hypertrophic cardiomyopathy mimicking an acute myocardial infarction where the diagnosis of myocardial hypertrophy was made by cardiac magnetic resonance. The method was able to identify the myocardial hypertrophy located in basal segments of anterior wall respect to echocardiography.