NOGAMI A et al.(5) View the monitor during imaging During imaging, the heart rate must be continuously monitored using a pulse oximeter or an ECG monitor. (6) Prepare for unexpected situations It should be ensured that the room is equipped with an electrical defibrillator to be used in an emergency, if necessary. A hospital manual for handling unexpected situations should be established. In addition, it should be kept in mind that the threshold and lead resistance need to be re-measured after imaging and the mode needs to be returned to the original setting.Recommendations are shown in Table 6. Electrophysiology StudiesThe clinical significance of induced arrhythmia depends on the underlying heart disease, type of arrhythmia, and induction protocol. Electrophysiology studies are considered less useful in patients with frequent premature ventricular contraction (PVCs) without structural heart disease.

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In addition to AVVR, hypoxia, and heart rate response, ventricular morphology is related to exercise capacity. Early Fontan operation may be beneficial in terms of exercise capacity, especially in the group RV patients.

Fontan patients exhibit markedly impaired CPX variables, and all the major variables, especially peak VO2 , predicted the risk of both morbidity and mortality.

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Cryo-therapy was used to effectively and safely ablate septal tachycardias in this group of 31 pediatric patients. Cryo-therapy may be more effective for AVNRT than septal AVRT.

Background-Inherited cardiac arrhythmia susceptibility contributes to sudden death during infancy and may contribute to perinatal and neonatal mortality, but the molecular basis of this risk and the relationship to genetic disorders presenting later in life is unclear. We studied the functional and pharmacological properties of a novel de novo cardiac sodium channel gene (SCN5A) mutation associated with an extremely severe perinatal presentation of long-QT syndrome in unrelated probands of different ethnicity. Methods and Results-Two subjects exhibiting severe fetal and perinatal ventricular arrhythmias were screened for SCN5A mutations, and the functional properties of a novel missense mutation (G1631D) were determined by whole-cell patch clamp recording. In vitro electrophysiological studies revealed a profound defect in sodium channel function characterized by Ϸ10-fold slowing of inactivation, increased persistent current, slowing of recovery from inactivation, and depolarized voltage dependence of activation and inactivation. Single-channel recordings demonstrated increased frequency of late openings, prolonged mean open time, and increased latency to first opening for the mutant. Subjects carrying this mutation responded clinically to the combination of mexiletine with propranolol and survived. Pharmacologically, the mutant exhibited 2-fold greater tonic and use-dependent mexiletine block than wild-type channels. The mutant also exhibited enhanced tonic (2.4-fold) and use-dependent block (Ϸ5-fold) by propranolol, and we observed additive effects of the 2 drugs on the mutant. Conclusions-Our study demonstrates the molecular basis for a malignant perinatal presentation of long-QT syndrome, illustrates novel functional and pharmacological properties of SCN5A-G1631D, which caused the disorder, and reveals therapeutic benefits of propranolol block of mutant sodium channels in this setting. (Circ Arrhythmia Electrophysiol.