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.

What endocardial right ventricular pacing site shows better contractility and synchrony in children and adolescents?

AIMS: Right ventricular (RV) apical (RVA) pacing can induce left ventricular (LV) dyssynchrony, remodeling, and dysfunction in children with complete atrioventricular block (CAVB). We compared the functional outcome of RVA with RV alternative pacing sites (RVAPS), including para-Hisian, septal, and outflow tract sites. METHODS: This is a single-center, retrospective study. Data were collected before pacemaker implantation (transvenous leads), postoperatively, at 6 months, and at 1-2-3-4 years. Electrocardiogram evaluation included QRS duration, axis, QTc/JTc, and QTc dispersion. Echocardiographic evaluation included 2-D/3-D assessment of ventricular dimensions (Z-score of LV end-diastolic dimension), function (ejection fraction), and synchrony. RESULTS: From 2009 to 2015, 55 patients with CAVB, aged 3-17 years, with or without other congenital heart defects, underwent RVAPS (30 patients, median age 11 years) or RVA (25 patients, median 12 years). All leads were positioned into the septum. Before implantation, no significant differences in parameters were observed, except for higher Z-score in RVAPS than in RVA. After implantation, at a median follow-up of 2.5 (range 1-6) years, the two groups showed no significant differences in LV dimensions, contractility, and synchrony. QRS intervals of RVAPS were significantly shorter than RVA. Clinical status was good and contractility/synchrony indexes were normal or adequate in all patients. CONCLUSIONS: In pediatric patients, RVAPS and RVA showed no significant differences in LV dimensions, contractility, and synchrony. Preimplantation dilated patients showed LV reverse remodeling. RVAPS demonstrated shorter QRS intervals. Therefore, septal pacing sites, either RVA or RVAPS, seem to determine good contractility and synchrony at a 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.

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.

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.

Catheter ablation of idiopathic ventricular tachycardia without the use of fluoroscopy.

BACKGROUND: Catheter ablation is the treatment of choice for many patients with idiopathic ventricular tachycardia (VT). Unfortunately, conventional catheter ablation is guided by fluoroscopy, which is associated with a small but definite radiation risk for patients and laboratory personnel. The aim of our study is to assess feasibility, success rate and safety of idiopathic VT ablation procedure performed without the use of fluoroscopy. METHODS: Nineteen consecutive patients undergoing idiopathic VT ablation at our institution have been included. The ablation procedures were performed under the guidance of electroanatomical mapping (EAM) system and intracardiac echocardiography (ICE). RESULTS: Nineteen patients (mean age 38.7 years) underwent ablation procedure for idiopathic VT. Twelve (63%) had outflow tract VT, 3 (18%) fascicular tachycardia, 2 (11%) peri-tricuspidal VT, 1 (5%) peri-mitral VT, and 1 (5%) lateral left free-wall VT. The mean procedural time was 170.2 ± 45.7 min. No fluoroscopy was used in any procedural phase. Acute success rate was 100%. No complication was documented in any patients. After a mean follow up of 18 ± 4 months, recurrences occurred in 2 patients. CONCLUSIONS: In our preliminary experience idiopathic VT ablation without the use of fluoroscopy was feasible and safe, using a combination of EAM and ICE. Success rate was excellent with no complication.

Relationship between cardiac autonomic function and sustained ventricular tachyarrhythmias in patients with an implantable cardioverter defibrillators.

AIMS: Low left ventricular ejection fraction (LVEF) is the main indication of implantable cardioverter defibrillators (ICD) in patients with dilated cardiomyopathy (DCM) for the primary prevention of sudden cardiac death, but ICD therapy at follow-up occurs in a minority of patients. We investigated whether heart rate variability (HRV) may improve risk stratification in DCM patients. METHODS AND RESULTS: We studied 42 patients (age 67.3 ± 3.5; 37 males) who had undergone ICD implant for either idiopathic or ischaemic DCM (LVEF <40%) 34.6 ± 19.7 months prior to the study (range 6-84). Patients underwent 24 h electrocardiographic Holter monitoring, and HRV was assessed over 2 hours in the afternoon showing stable sinus rhythm. Left ventricular ejection fraction was measured by two-dimensional echocardiography. The serum levels of C-reactive protein and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were also obtained. The primary endpoint was the occurrence of appropriate ICD shocks in the 6 months preceding the study. The occurrence of appropriate ICD discharge from ICD implant was considered as a secondary endpoint. In the last 6 months, appropriate ICD shocks had occurred in seven patients (17%). There were no differences between patients with and without ICD shocks in clinical variables, as well as in LVEF and in C-reactive protein and NT-proBNP serum levels. In contrast, most HRV parameters were significantly depressed in patients with, compared with those without, ICD shocks; the most significant difference was shown for the average of the standard deviations of RR intervals in all consecutive 5 min segments (n » 12) within the 2 h (26.7 ± 9 vs. 39.7 ± 14 ms; P = 0.02) in the time domain and for LF amplitude (8.4 ± 3 vs. 14.8 ± 7 ms; P = 0.02) in the frequency domain. Implantable cardioverter defibrillator discharge had occurred in 11 patients (26%) since ICD implant (average 35 months). No clinical or laboratory variable showed significant differences between patients with or without ICD discharge, except very low-frequency (VLF) amplitude (23.8 ± 7 vs. 30.8 ± 10.6 ms, respectively; P = 0.049). CONCLUSION: In ICD patients with reduced LVEF, several depressed HRV indices were significantly associated with appropriate ICD shocks in the previous 6 months, and VLF amplitude was the only variable significantly associated with ICD shocks recorded since ICD implant. These data suggest that full HRV analysis might be helpful for improving risk stratification for life-threatening ventricular arrhythmias and ICD indication in patients with DCM.

Long-term results of cardiac transplantation in patients 65 years of age and older: a comparative analysis.

BACKGROUND: Advanced age is viewed by some transplant centers as a contraindication for heart transplantation secondary to concerns regarding decreased survival. METHODS: Between January 1992 and June 2002, 63 of 881 (7.2%) orthotopic heart transplants were performed in patients above 65 years. These patients were compared to 63 recipients below age 65 who were matched for sex, etiology of heart failure, United Network for Organ Sharing status, and immunosuppression therapy era. RESULTS: Mean age was 67.1 +/- 2.3 years (range, 65.0 to 74.8) for the older group and 48.1 +/- 14.5 years (range, 18.3 to 64.4) for the younger group (p < 0.001). There was no significant difference in the incidence of diabetes, hypertension, chronic obstructive pulmonary disease, or peripheral vascular disease between the groups (p = not significant) although there were more patients with prior myocardial infarctions in the older group (p < 0.001). There was no significant difference in overall survival between the groups, with 1-, 3-, 5-, and 10-year actuarial survival of 85.8%, 80.3%, 73.1%, and 49.9% for the older group; and 86.9%, 83.4%, 75.0%, and 57.0% for the younger group (p = 0.597). Postoperative intensive care unit stay and overall hospital stay were similar for the two groups (p = not significant). There was no significant difference between the groups in freedom from infection or rejection at 1, 3, or 5 years after transplant (p = not significant) although the incidence of transplant coronary artery disease was higher in the older group (p = 0.025). CONCLUSIONS: These data demonstrate similar short-term and long-term results for elderly and young recipients undergoing cardiac transplantation. This supports proceeding with transplantation in carefully selected elderly patients.