Non-invasive assessment of direction of right atrial activation during atrial fibrillation using correlation function analysis.

ECGs were recorded from three electrodes attached at
the corners of an equilateral triangle positioned around
the location of electrode V1. The atrial signal between
QRST complexes was subjected to correlation function
analysis to reveal differences in activation times between
the electrode sites. The time differences found were used
to calculate the direction of activation across the body
surface. Twenty-three subjects were studied during sinus
rhythm (SR), intraoperatively confirmed typical and reverse
typical atrial flutter, or during paroxysmal or permanent
atrial fibrillation (AF).
Subjects studied during SR and patients with typical
atrial flutter exhibited a uniform direction of activation,
with the main vector pointing downwards. The propagation
of atrial activation during permanent AF did not show
a consistent direction, while patients with paroxysmal AF
exhibited more uniform activation vectors, corresponding
to the direction observed in patients with atrial flutter.