Adverse device-device interaction between pacemaker and subcutaneous implantable cardiac defibrillator.

A 26-year-old patient with prior surgery for Ebstein's anomaly and a pacemaker (placed for post-surgical heart block and poor underlying rhythm) underwent SICD was placement. During defibrillation testing, device-device interaction led to undersensing of ventricular fibrillation with failure to shock. Increasing the pacemaker sensitivity resolved the problem but post shock pacing was unable to capture the heart after both shocks. The patient underwent removal of both the pacemaker and the SICD and placement of a transvenous ICD. Complex device-device interactions can occur in patients who are pacemaker dependent and undergo placement of a SICD.

Optimization of myocardial strain imaging and speckle tracking for resynchronization after congenital heart surgery in children.

Cardiac resynchronization therapy can improve cardiac function in children with heart failure. The optimal method of assessing dyssynchrony has not been established. Newer tissue Doppler techniques such as strain assessment and speckle tracking appear to be promising for optimization of resynchronization. Two children aged 7 weeks and 4 months, with transposition of the great arteries and ventricular septal defect, and double outlet right ventricle with pulmonary stenosis, developed heart block after surgery. Conventional epicardial pacing resulted in heart failure in both. Upgrade to cardiac resynchronization therapy was not associated with normalization of function by echo, necessitating optimization. Baseline ventriculo-ventricular delay was 4 ms. Speckle tracking strain assessment was performed while adjusting ventriculo-ventricular delay. In Patient 1, synchrony was best with left ventricular (LV) activation preceding right ventricular (RV) by 30 ms. In Patient 2, it was best with RV preceding LV by 20 ms. At follow-up, both patients had normalization of function. In each case, optimization and reprogramming could be done live with no need for offline analysis. Speckle tracking strain analysis appears to be successful in the live, on-site optimization of cardiac resynchronization therapy in children. Further studies may help refine this process further.

Recent advances in pediatric cardiology--electrophysiology, transcatheter and surgical advances.

Whereas the medical advances were reviewed in the previous paper, electrophysiological, transcatheter and surgical advances will be the focus in this review. Greater understanding of the arrhythmias, development of non-pharmacological treatment, namely catheter ablation and internal cardioverter-defibrillator (ICD) and miniaturization pacemakers and IDs have occurred in the last decade so that the methods could be applied to smaller and more complex patient population. Surgery has been the traditional treatment option for palliation and correction of congenital and acquired heart defects in infants and children. During the last one to one and one-half decades, a remarkable number of transcatheter methods were developed and refined. These developments during the last decade were reviewed and include long-term results of balloon dilatation procedures, transcatheter closure of atrial septal defects, patent ductus arteriosus, and ventricular septal defect, percutaneous valve replacement, intravascular stents to manage vascular obstructive lesions that can not be satisfactorily balloon-dilated, catheter completion of Fontan procedure, myocardial reduction in hypertrophic cardiomyopathy and other miscellaneous procedures. Recent advances in the transcatheter modes of therapy have added a new dimension to the management of neonates, infants and children with heart disease. They should now be added to the armamentarium available to the Pediatrician and Pediatric Cardiologist in the management of cardiac problems in the pediatric patient. Surgical methods and concepts have been greatly refined such that surgery can be undertaken even in the sickest and most complex patient. The majority of congenital heart defects can be corrected by open heart surgery; some require prior palliation and others can be operated without prior palliation. Recent advances in various defects were reviewed.

Nonautomatic focal atrial tachycardia: characterization and ablation of a poorly understood arrhythmia in 38 patients.

Nonautomatic focal atrial tachycardia (NAFAT) is a rare and poorly understood arrhythmia either due to microreentry or triggered mechanism. NAFAT was defined as a focal atrial tachycardia which was inducible with pacing maneuvers in the electrophysiology lab. We reviewed the charts and EP study reports of all 38 patients with NAFAT, who underwent an EP study at our center between April 1994 and September 2000. Patients' were predominantly female (n = 31, 82%), aged 11-78 years (median 46). The mean age at presentation was 31 years (range 7-71 years). None of the patients had structural heart disease or had undergone prior heart surgery. Electroanatomic mapping (EAM) was performed in 22 patients and showed no scars in the atrium. A total of 45 foci were identified (range 1-3 foci/patient). Anatomically NAFAT foci were predominantly right atrial (n = 35) rather than left (n = 10). The NAFAT cycle length ranged from 270 to 490 (mean +/- SD; 380 +/- 69 ms) and was significantly lower in patients younger than 24 years of age. Ablation, attempted for 42 foci was successful in 33 (79%). The success rate in the EAM group was 20/25 foci (80%) compared to 13/18 (72%) in the non-EAM group. In conclusion, NAFAT is a rare arrhythmia which predominantly affects women with no other associated cardiac disease. It mainly occurs in the right atrium, affects all ages and is amenable to catheter ablation.