13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

RT-177

To understand atrial arrhythmias, we need to make nomenclature match anatomy!

Francisco G. Cosío, Robert H. Anderson, Karl Kuck, on behalf of the Cardiac Nomenclature Study Group of the Working Group of Arrhythmias of the European Society of Cardiology.
Cardiology Service, University Hospital of Getafe, Madrid, Spain

Introduction

Clinical cardiac electrophysiology was born in the late 60s, when the first recording was made of the His bundle electrogram¹. There was then a huge expansion during the late 70s and early 80s, mainly due to the advances in understanding the Wolff-Parkinson-White syndrome and atrioventricular nodal tachycardia, leading to surgical treatment of the abnormal rhythms². It was at this point that electrophysiology first came in close contact with cardiac anatomy, and a view of the atrioventricular junctions was adopted that has provided the currently accepted terminology. According to this terminology, the atrioventricular junctions are viewed from their atrial aspect, and are described as having anterior-posterior and right-left lateral coordinates (Fig. 1). According to this arrangement, the anterior aspect is that closest to the pulmonary valve, and posterior is the opposite side, made up of the coronary sinus and the diaphragmatic surface of the ventricular mass. This convention, however, represents a major departure from the true anatomic coordinates. This is because, traditionally, the body is described in its upright position, with note then taken of the three orthogonal planes: superior (cranial) to inferior (caudal); anterior (ventral) to posterior (dorsal) dimension; and left lateral to right lateral (with the medial plane representing the midpoint of the body as seen in the frontal projection). Despite the obvious discrepancies between this anatomic framework and the descriptions proposed for the atrioventricular junctions², the inappropriate terms became widely accepted, and are now universally applied in electrophysiologic laboratories.

Fig. 1: Schematic representation of the atrioventricular (AV) rings, aortic valve, AV node and coronary sinus using the current terminology employed by electrophysiologists (italics), and the correct anatomic orientation. The view is from the ventricular side.

When ventricular tachycardia mapping was first mapped, it was recognized that the ventricles themselves had a complex structure, and the terms developed to describe this arrangement produced no special conflict³. Then, over the 80s, there developed a particular and progressive interest in atrial arrhythmias, leading in the 90s to important advances in mapping and ablation of atrial flutter and atrial tachycardia^4,5, and some initial attempts at catheter ablation of atrial fibrillation^6,7. It then became plain that the nomenclature used for description of accessory pathways and the atrioventricular node produced real problems⁸.