Cryoablation with an 8-mm-Tip Catheter for Right-Sided Accessory Pathways in Children.

BACKGROUND: Cryoablation is increasingly utilized in children because of its safety profile. Recently, larger catheter tips have been more widely used to improve long-term success rates. The aim of this study was to assess the safety and efficacy of 8-mm-tip catheters for cryoablation of right-sided accessory pathways (APs) in children. METHODS: Electrophysiological procedures were performed using the EnSite™ system (St. Jude Medical Inc., St. Paul, MN, USA). RESULTS: Between July 2010 and July 2014, 54 patients (mean age: 13.1 ± 3.7 years) underwent cryoablation using an 8-mm-tip catheter. In 18 of 54 (33%) patients where an 8-mm-tip catheter was the first-choice catheter, the success rate was 18 of 18 (100%). There was a history of previous failed attempts or recurrence with radiofrequency ablation and/or 6-mm-tip cryoablation in 36 of 54 (67%) patients. The success rate in these patients was 24 of 36 (67%). No fluoroscopy was used in 34 of 54 procedures. The recurrence rate was six of 42 (14%) during a mean follow-up period of 32 ± 15 months. In one patient, transient atrioventricular block occurred. CONCLUSIONS: Cryoablation with an 8-mm-tip catheter for right-sided APs in children who weigh over 40 kg appears to be safe and acutely effective in cases where conventional ablation methods fail and also as a first choice for ablation procedure. However, the recurrence rate still seems to be high.

Role of thrombophilia factors in acute systemic-pulmonary shunt obstruction.

BACKGROUND: Systemic-pulmonary shunts are widely used in initial palliation in cyanotic congenital heart disease. The incidence and the relationship between acute shunt obstruction and thrombophilia are not precisely defined. The aim of this study was to determine the frequency of shunt obstruction in the early postoperative period, and to define the frequency and presence of thrombophilia factors in patients treated for acute shunt thrombosis. METHODS: Between October 2010 and October 2012, 77 patients who had systemic-pulmonary shunt operation were included in this prospective study. Patients who developed shunt obstruction were examined in terms of inherited and acquired thrombophilia factors. RESULTS: Median patient age was 61 days and median weight was 4.3 kg. Thirty-three patients were neonates. Diameter of the Gore-Tex grafts used for the shunt ranged from 3 mm to 5 mm. Acute shunt occlusion rate was 10% (8/77), and all of these occurred in the first 24 h. Thrombophilia was found in three of eight patients who underwent intervention (surgical and/or transcatheter) due to shunt thrombosis (presence of anti-phospholipid antibodies, n = 1; protein C deficiency, n = 1; and factor V Leiden mutation, n = 1) and only one patient died. CONCLUSIONS: Acute shunt obstruction developed in 10% of patients who underwent systemic-pulmonary shunt, and emergency surgery or transcatheter intervention can be life saving in this context. Acute shunt obstruction can occur due to mechanical and hemodynamic problems, but clinicians should also consider and evaluate thrombophilia factors.

Holter electrocardiography findings and P-wave dispersion in pediatric patients with transcatheter closure of atrial septal defects.

BACKGROUND: This study aimed to determine the frequency of postintervention arrhythmia and factors associated with the development of arrhythmia, including the correlation between arrhythmia and P-wave dispersion, and the effects of the latter on transcatheter closure of atrial septal defects (ASDs). METHODS: Holter ECG recordings were performed before and after the intervention and 6 and 12 months later in 47 of the 59 patients who had undergone transcatheter ASD closure and once in the healthy control subjects. RESULTS: A statistically significant correlation was identified between the patients' arrhythmia grade according to Lown's system and each of the following: the number of defects, the size of the atrioventricular valve rim, the presence of an atrial septal aneurysm. CONCLUSION: The frequency of arrhythmia increases after transcatheter ASD closure, gradually decreases within the next year, and is most frequently of a benign nature. Lown's arrhythmia grading of patients occluded with either the Amplatzer septal occluder (ASO) or the Cardio-O-Fix septal occluder (CSO) were compared, and the arrhythmia frequency was higher with the latter. One day after the intervention, the P maximum (Pmax ) and the P dispersion(Pdis ) values were not increased but in fact slightly reduced in patients occluded with either ASO or CSO. An improvement in the electrical system resulting from early anatomical and mechanical healing following transcatheter ASD occlusion may explain the reduction in the Pmax and Pdis values.

Assessment of atrioventricular conduction following cryoablation of atrioventricular nodal reentrant tachycardia in children.

BACKGROUND: Early-onset transient atrioventricular block (AVB) is a rare occurrence following cryoablation of atrioventricular nodal reentrant tachycardia (AVNRT), despite lack of any AVB at the end of the procedure. The purpose of this prospective study was to assess AVB shortly after successful cryoablation of AVNRT in children. METHODS: A 6-mm-tip cryocatheter was used in 39 procedures. An 8-mm-tip catheter was used in 11 procedures. Twelve-lead electrocardiograms (ECGs) and 24-hour ambulatory ECGs were performed 24 hours prior to the procedure and immediately following the procedure. All procedures were done using the EnSite system (St. Jude Medical, St. Paul, MN, USA) without fluoroscopy. RESULTS: Although nine (18%) patients developed variable degrees of transient AVB during the procedure, all of them had normal atrioventricular (AV) conduction at the end of the procedure and did not require any intervention. Four of these patients had variable degrees of transient AVB following the procedure despite having normal AV conduction at the end of the procedure. One developed Mobitz type I AVB, which lasted for 11.5 hours, and the other three experienced 2:1 AVB, which lasted for 2, 8, and 24 hours, respectively. All patients had complete resolution of the AVB, which was also documented with the 24-hour ambulatory ECGs after the procedure. CONCLUSION: Early transient AVB can develop following AVNRT cryoablation even if AV conduction is normal at the end of the procedure. Despite the transient AVB in the initial 24 hours after the procedure in some cases, there is no evidence for ongoing AV nodal dysfunction.

Near infrared spectroscopy monitoring in the pediatric cardiac catheterization laboratory.

Near-infrared spectroscopy (NIRS) is a noninvasive method used to evaluate tissue oxygenation. We evaluated the relationship between cerebral and renal NIRS parameters during transcatheter intervention and adverse events in the catheterization room. Between January 1 and May 31, 2012, 123 of 163 pediatric patients undergoing cardiac catheterization were followed by NIRS. All were monitored by electrocardiography, noninvasive blood pressure measurement, pulse oxymetry, initial and final blood lactate level measurement. The number of interventional procedures was 73 (59%). During the procedures, 39 patients experienced a total of 41 adverse events: 18 (19.5%) had desaturation, 10 (8.1%) arrhythmia, three (2.4%) had respiratory difficulty, six (4.8%) had a situation calling for cardiopulmonary resuscitation, three (2.4%) had anemia necessitating transfusion, and one (0.8%) had a cyanotic spell. Cranial NIRS values worsened in 12 (9.8%) and renal measurements worsened in 13 (12.5%) patients. The sensitivity and specificity of a 9% impairment of cranial values were 90 and 61%, respectively, while the corresponding calculations for a 21% fall in renal measurements were 54% sensitivity and 90% specificity. When arrhythmia developed, NIRS values fell simultaneously, while the development of a desaturation problem was heralded by NIRS falling 10-15 s earlier than changes in pulse oxymetry; on improving saturation, NIRS returned to earlier values 10-15 s before pulse oxymetry readings. NIRS monitoring may provide an early warning with regard to complications likely to develop during a procedure. A fall of 9% in cranial NIRS values, or of 21% in renal measurements, should raise clinician awareness.

Percutaneous right ventricle outflow tract stenting in a patient with trisomy 18 associated with double outlet right ventricle.

Trisomy 18, or Edwards syndrome, is the second most common chromosome anomaly after trisomy 21. Various types of congenital heart diseases are seen in the majority of trisomy 18 patients. Palliative treatment of right ventricular outflow tract (RVOT) stenosis includes options like balloon dilatation, stenting and surgery. Herein, we present a case with trisomy 18 and double outlet right ventricle, pulmonary stenosis, and ventricular septal defect. During the follow-up, at the age of three months, his saturation dropped to 70% and an interventional procedure was planned. The patient was considered high risk, and after discussing treatment options with the family, RVOT stenting was chosen. The patient was lost on the 8th day of the follow-up.

Catecholaminergic polymorphic ventricular tachycardia detected by an implantable loop recorder in a child.

We present a six-year-old boy with a history of recurrent syncope whose physical examination and family history were inconclusive. Laboratory findings, 12-lead ECG, chest radiography, Holter monitoring, event recorder monitoring, echocardiography, coronary computed tomography (CT) angiography, Brugada challenge test (ajmaline), cranial magnetic resonance imaging, and awake/sleep electroencephalogram were all unremarkable. Since syncope was exercise-induced, an electrophysiology study was also performed, but revealed no inducible ventricular arrhythmias. Implantable loop recorder (ILR) was implanted. Three weeks later, bidirectional ventricular tachycardia was found in ILR record during presyncope that was related to exercise. The patient, with the diagnosis of catecholaminergic polymorphic ventricular tachycardia, was started on high-dose beta-blocker therapy. Due to the recurrence of syncopes despite the presence of beta-blockers, an implantable cardioverter defibrillator was implanted.

Catheter ablation of drug resistant supraventricular tachycardia in neonates and infants.

BACKGROUND: The aim of this study was to evaluate the indications, results and complications of radiofrequency ablation (RFA) and transcatheter cryoablation (TCA) in neonates and infants with incessant drug-resistant supraventricular tachycardia (SVT). METHODS: Out of 225 patients who underwent RFA and TCA at our center between January2010 and February 2012, 5 patients under the age of 1 (4 male, 1 female) were evaluated. The indication for RFA/TCA was recurrent hemodynamically compromising drug-resistant SVT. RESULTS: Over a 2-year period, 6 ablation procedures were performed in 5 patients. Average patient age was 3.3 ± 3.9 months (12 days - 9.5 months); average patient weight was 5.4 ± 2.2 kg (3.5-9 kg). One patient had ventricular septal defect, 1 had corrected transposition of great arteries, ventricular septal defect, right ventricular hypoplasia and pulmonary hypertension, while 3 had only patent foramen ovale. Electrophysiology study showed 1 accessory pathway in each patient (right posteroseptal in 2, left posteroseptal in 2 and left lateral in 1). The pathway was manifest in 1 patient with Wolff-Parkinson-White syndrome (WPW) and concealed in the rest. Two of the concealed pathways had slow conduction time and decremental properties (the permanent form of junctional reciprocating tachycardia). Two patients underwentTCA and 3 - RFA, with an acute success rate of 100%. In the first week after the procedure, the patient with the complex cardiac anomaly and WPW developed recurrence and under went ablation again. Four of the procedures were carried out using an electroanatomic mapping system besides fluoroscopy. Average procedure time was 167 min (100-234); fluoroscopy time was 8.2 min (0.7-19.7). None of the patients developed major complications. After the average follow-upperiod of 6.5 months (3-18), all patients were symptom-free without medication. CONCLUSIONS: RFA and TCA can be performed successfully in neonates and infants within cessant medically refractory SVT.

Cryoablation of anteroseptal accessory pathways in children with limited fluoroscopy exposure.

Due to its safety profile, cryoablation is used increasingly in pediatric patients, especially for septal arrhythmia substrates. Recent advances in electroanatomical-mapping technologies have resulted in a decrease or complete elimination of fluoroscopy exposure during catheter ablation procedures. The aim of this study was to assess the efficacy and safety of cryoablation of anteroseptal accessory pathways (APs) using electroanatomical-mapping system guidance with limited fluoroscopy exposure. A total of 24 patients underwent cryoablation of anteroseptal APs between July 2010 and April 2012. Cryomapping was performed with a 6 mm-tip catheter at -30 °C before the lesions were delivered. An 8 mm-tip catheter was used in one patient. The EnSite system (St. Jude Medical, St Paul, MN) was used in all procedures. The mean age was 11.9 ± 4.3 years. Acute success rate was 95.8 % (23 of 24). The mean procedure and cryoablation durations were 168 ± 58 min and 1,463 ± 525 s, respectively. Limited fluoroscopy was used only in 7 patients, and the mean fluoroscopy time was 1.7 ± 1.8 min (range 0.1-4 min) in these patients. Recurrence was noted in 2 patients (8.7 %) who underwent a second successful cryoablation procedure. The patient who underwent a failed attempt during the first procedure was successfully treated with a repeat procedure. The resultant long-term success rate was 100 % at a mean follow-up period of 14.2 ± 7.7 months. There were no complications except for transient atrioventricular block in one patient. Cryoablation of anteroseptal APs can be performed effectively and safely in children using a limited fluoroscopic approach with the help of electroanatomical-mapping systems.

Successful cryoablation of Mahaim tachycardia in a child with Ebstein's anomaly.

Mahaim fibers with decremental atrioventricular (AV) node-like conduction properties comprise less than 3 % of accessory pathways. Radiofrequency ablation of right atriofascicular pathways guided by a distinct Mahaim potential detected at the anterolateral to posterolateral tricuspid annulus or in the right ventricular free wall is a safe and highly effective treatment method. The case report presents a 16-year-old boy with Ebstein's anomaly and symptomatic wide complex tachyarrhythmia. The electrophysiologic study and the entire ablation procedure were performed using a three-dimensional mapping system (EnSite Velocity; St. Jude Medical Inc., St. Paul, MN, USA). No fluoroscopy was used during the procedure. Electrophysiologic evaluation demonstrated typical atrioventricular nodal reentrant tachycardia and Mahaim tachycardia with a wide QRS and a left bundle branch block pattern. After Mahaim potential was located at the lateral tricuspid annulus, successful cryoablation was performed with an 8-mm-tip catheter followed by slow pathway ablation to eliminate typical atrioventricular nodal reentrant tachycardia. Cryoablation with an 8-mm-tip catheter can be an alternative treatment option for children with Mahaim tachycardia.

Combined resection and radiofrequency ablation of rhabdomyoma in a child with sustained ventricular tachycardia.

Cardiac rhabdomyoma is a benign tumor of the heart in childhood and can be associated with life-threatening arrhythmia. In this report, we present the case of a 2-year-old male with right ventricular rhabdomyoma, who was admitted with syncope that was associated with episodes of sustained ventricular tachycardia. The patient underwent combined surgical resection and radiofrequency ablation of the tumor. There was no recurrence of ventricular tachycardia after surgery.