The two-signal model of T-cell activation is still valid after 30 years. The recent understanding of the first signal intricacy and its tight relationship with the second signal have thrown decisive light on T-cell activation processes and the complex molecular events that occur on the surface and within the T cell. Furthermore, the recognition of numerous accessory pathways that, in addition t...

We review the essential role of maternal factors in pattern formation for Xenopus laevis, focusing on VegT, Vg1, and Wnt11. Results from loss of function experiments demonstrate a clear requirement for these genes in germ layer specification, dorsal-ventral axis formation, and convergence extension. We also discuss these genes in the broader context of metazoan development, exploring whether an...

The observation of a left sided accessory pathway with decremental properties is rare. We describe the behaviour of one of these pathways which was characterized by the presence of retrograde conduction (not previously reported) and thus inducibility of atrio-ventricular orthodromic reentrant tachycardia.

The case is presented of a five-year-old boy with Wolff-Parkinson-White syndrome, who had undergone three surgical palliations because of congenitally corrected transposition of the great arteries, ventricular septal defect and pulmonary trunk near-atresia. Successful and uncomplicated radiofrequency catheter ablation of an accessory pathway located across the systemic atrioventricular valve ri...

Left ventricular hypertrabeculation/noncompaction (LVHT) is an uncommon type of genetic cardiomyopathy characterized by trabeculations and recesses within the ventricular myocardium. LVHT is associated with diastolic or systolic dysfunction, thromboembolic complications, and arrhythmias, including atrial fibrillation, ventricular arrhythmias, atrioventricular block and Wolff-Parkinson-White syn...

This study was conducted on the atrioventricular node (AVN) and atrioventricular bundle (AVB) of fivefour-month-old ovine fetuses. The histological structure of these components was studied by routinehistological techniques and use of specific staining methods. The AVN was caudally located adjacent to theroot of the aorta. It was almost spherical in shape and consisted of twisty cells. The node...

Wolff-Parkinson-White (WPW) syndrome occurs due to an accessory atrioventricular bypass tract. The prevalence of WPW electrocardiographic pattern has been estimated to be 0.1%-0.3% in the general population, with the annual incidence of new cases reported to be 4 per 100,000 population per year (l). While the commonest age of presentation is the second decade of life (2)/ unusually tachycardia ...

Background—Atriofascicular and decremental atrioventricular pathways are variants of accessory pathways with anterograde decremental conduction properties. They result in typical wide Quantronic Resonance System (QRS) tachycardia of left bundle branch block morphology. Data on the sinus rhythm electrocardiographic characteristics are limited. Methods and Results—Thirty patients with accessory p...

Between March 1955 and March 1981, 52 adult patients (age 20 years or older) with partial atrioventricular canal (PAVC) were examined at the Mayo Clinic. Forty patients were in New York Heart Association (NYHA) functional class I or II. The ECG showed right bundle branch block with left-axis deviation in 48, first-degree atrioventricular block in 33 and atrial fibrillation in nine. Preoperative...

A lthough still in its infancy, ablation of accessory pathways using radiofrequency energy delivered through a catheter already has an important history. The technique evolved from the demonstration that accessory pathway potentials could be recorded with standard multipolar electrode catheters.' It was only a natural extension of the technique to learn ways to eliminate accessory pathway condu...