Two patients who developed left bundle-branch block with increase in heart rate are presented. Atrial pacing during His bundle recording studies showed differing responses in the ventricular specialized conduction system of the two patients. In one, the onset of left bundle-branch block was associated with no change in the previously normal HVinterval (so msec), while in the second the HV inter...

Of 22 children with congenital complete heart block (CCHB) available for study, 14 (63.6%) were born to 11 mothers with clinical or laboratory evidence of connective tissue disease, primarily lupus erythematosus (LE). Seven mothers had both clinical and laboratory evidence of disease while four had only positive laboratory studies including fluorescent antinuclear antibody, rheumatoid factor, a...

Ventricular arrhythmias are frequently observed in the elderly population secondary to alterations of electrophysiological properties that occur with the normal aging process of the heart. However, the underlying mechanisms remain poorly understood. The aim of the present study was to determine specific age-related changes in electrophysiological properties and myocardial structure in the ventr...

SUMMARY Experimental studies were carried out in animals with intracellular and extracellular electrodes used to record simultanieously from the atrium, atrioventricular (A-V) node, bundle of His, bundle branches, Purkinje fibers, and ventricles to deteimine the site of conduction delay and block in Mobitz type II second-degree heart block. Type II block with block occurring within the His-Purk...

211 Volume XI, no. 2 : May 2010 progressing from high-level AV block through second-degree to first-degree heart block before complete resolution.2 The AV node is most commonly involved, but any level of the conduction system can be affected. Clinical heart failure is observed in approximately 10% of patients, and dilated cardiomyopathy can be a long-term consequence of untreated Lyme carditis....

whether the method, in addition to its undoubted scientific interest, yields any information having a direct bearing upon the problems of diagnosis, prognosis, and treatment. It must be admitted that in many cases no further knowledge is obtained by its use than can be derived from ordinary methods of examination. At the same time it may fairly be claimed for it that in some cases no other meth...

Relative contributions of the atria and the atrioventricular (AV) node to AV conduction were studied in isolated, blood-perfused dog hearts. The functional refractory period of the atria, although shorter than that of the AV node, determined the functional refractory period of the entire transmission system in 50% of the hearts. Slow atrial conduction of early beats greatly influenced the shape...

Calmodulin kinase II (CaMKII) mediates critical signaling pathways responsible for divergent functions in the heart including calcium cycling, hypertrophy and apoptosis. Dysfunction in the CaMKII signaling pathway occurs in heart disease and is associated with increased susceptibility to life-threatening arrhythmia. Furthermore, CaMKII inhibition prevents cardiac arrhythmia and improves heart f...

Conduction abnormalities of the His-Purkinje (HP) system are common sequelae of surgical repair of heart defects. Standard electrophysiologic recordings may fail to demonstrate abnormalities of the HP system when routine intervals are measured. When the conduction system is stressed, certain HP features that may indicate latent conduction disease within the HP system can be revealed. These feat...