Agc. Sutton et al., The use of atropine for facilitation of direct current cardioversion from atrial fibrillation - Results of a pilot study, CLIN CARD, 22(11), 1999, pp. 712-714
Background: The importance of the role of the autonomic nervous system (ANS
) in the initiation and propagation of atrial fibrillation has been demonst
rated in the condition of paroxysmal atrial fibrillation. However, the role
of the ANS in patients with chronic atrial fibrillation is less clear. Som
e patients with chronic atrial fibrillation are resistant to the standard t
echniques of direct current (DC) cardioversion,
Hypothesis: We sought to investigate whether excessive vagal tone might pre
vent the restoration of sinus rhythm and to establish that the abolition of
vagal tone using intravenous atropine will facilitate DC cardioversion in
patients with atrial fibrillation who are resistant to the standard cardiov
ersion techniques.
Methods: Beginning in August 1994, a change in the protocol for elective DC
cardioversion of atrial fibrillation was made to include the use of intrav
enous atropine for patients resistant to the standard techniques of DC card
ioversion.
Results: Over a 2-year period, 140 elective cardioversions were performed f
or atrial fibrillation. Sinus rhythm could not be restored on 31 occasions.
intravenous atropine prior to a further 360 J shock with paddles in the an
teroposterior position allowed sinus rhythm to be restored on nine occasion
s. Patients with successful cardioversion after atropine had significantly
better left ventricular function than those who remained in atrial fibrilla
tion (p = 0.001) as well as a tendency toward a smaller left atrium.
Conclusion: This study suggests that high vagal tone, which is dominant in
patients with structurally normal hearts, may prevent the termination of at
rial fibrillation by standard techniques of DC cardioversion, and that the
abolition of high vagal tone by atropine facilitates the restoration of sin
us rhythm.