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

January 24-31, 1998
Marilleva, Trento, Italy

RT-160

Mechanism of induction of typical atrial flutter by programmed stimulation

Francisco G. Cosío, María López-Gil*, Fernando Arribas*, Agustín Pastor, Ambrosio Núnez.
Cardiology Service, University Hospital of Getafe, Madrid,
*Arrhythmia Unit, University Hospital 12 de Octubre, Madrid, Spain

Introduction

Mapping studies have shown that typical flutter is due to macroreentry in a counterclockwise direction (up the septal and posterior walls and down the anterior right atrial wall) surrounding the venae cavae, linked by a line of functional block at the crista terminalis¹. The lower path of the circuit is the isthmus between the inferior vena cava and the tricuspid ring (CTI)^2-4 and the upper turning point is probably anterior to the superior vena cava^5,6. The same circuit can be used in a reversed direction, giving an electrocardiographic (ECG) pattern generally characterized by positive deflections in the inferior leads^7-9 however, its clinical incidence is about 1/10 that of typical flutter¹⁰. The reason for the more frequent clinical presentation of counterclockwise reentry is unclear.

We have studied modes of initiation of typical flutter by programmed stimulation with multiple simultaneous recordings from the septal and anterior RA, allowing continuous recording of activation from within the flutter circuit.