BACKGROUND The MRI-compatible electrophysiology system previously used for MR-guided left ventricular electroanatomic mapping was enhanced with improved MR tracking, an MR-compatible radiofrequency ablation system and higher-resolution imaging sequences to enable mapping, ablation, and ablation monitoring in smaller cardiac structures. MR-tracked navigation was performed to the left atrium (LA)...

Left ventricular noncompaction (LVNC) is a genetically heterogenous form of cardiomyopathy which may remain undiagnosed till adulthood due to the late presentation of typical symptoms such as dyspnea, congestion, ventricular arrhythmias and thromboembolism. Symptomatic bradycardia secondary to persistent sinus node dysfunction is very rare. Coexistent cardiac defects are common in children howe...

His bundle electrograms were recorded in 2 adult cases of congenital corrected transposition of the great arteries. Both patients had prolonged HV conduction and a His potential that was wide. These findings are different from those reported in congenital atrioventricular block without ventricular inversion wherein an abnormality within the AHperiod has been found. It is suggested that these di...

Cardiac sarcoidosis is an uncommon cause of cardiac arrhythmias and cardiomyopathy. We describe a case of cardiac sarcoidosis presenting as an accelerated junctional rhythm and complete atrioventricular (AV) block, without severe left ventricular (LV) dysfunction or pulmonary symptoms. Computer tomography (CT) of the chest and mediastinal lymph node biopsy confirmed the diagnosis. Dual-chamber ...

Atrioventricular (AV) conduction was studied in anesthetized, open-chest, 1-35-day-old goats. Atrial, bundle of His, and ventricular bipolar electrograms were recorded, and the functional refractory periods of the AV conduction system and the ventricles were determined. Supraventricular premature excitation invaded the ventricles during their vulnerable period. This AV conduction property is di...

VENTRICULAR FUSION, summation or combination beats occur when two separate pacemakers compete for control of the ventricles. The usual pair of pacemakers are the sinoatrial node and an ectopic ventricular focus; but any pair of pacemakers, whose impulses invade the ventricular myocardium more or less simultaneously but at different points, can produce fusion beats. An ectopic atrial focus or th...

VENTRICULAR FUSION, summation or combination beats occur when two separate pacemakers compete for control of the ventricles. The usual pair of pacemakers are the sinoatrial node and an ectopic ventricular focus; but any pair of pacemakers, whose impulses invade the ventricular myocardium more or less simultaneously but at different points, can produce fusion beats. An ectopic atrial focus or th...

This work intends to be a review of the current status of knowledge on the cardiac conduction system in the crib death as well as remaining challenges, including reflections upon authors' personal works as well as many studies by others. The cardiac conduction system findings of resorptive degeneration, His bundle dispersion, Mahaim fibers, cartilaginous meta-hyperplasia, persistent fetal dispe...

Orthodromic tachycardia is the most common arrhythmia in patients with Wolff-Parkinson-White syndrome. It is often initiated during incremental ventricular pacing that requires the onset of retrograde block along the normal pathway (that is, atrioventricular [AV] node-His-Purkinje system) with concomitant retrograde atrial activation by way of the accessory pathway. However, the site of retrogr...