From the Department of Medicine, Case Western Reserve University, and
University Hospitals of Cleveland, Cleveland, Ohio.
Correspondence to Albert L. Waldo, MD, Division of Cardiology, Lakeside 5038, University Hospitals of Cleveland, 11100 Euclid Ave, Cleveland, OH 44106. E-mail alw2{at}po.cwru.edu
Temporary epicardial wire
electrodes placed during open heart surgery for potential
diagnostic and/or therapeutic use in patients in the
immediate postoperative period have been used safely and effectively as
part of standard care for a long time.1 2 3 4
We have also known that synchronized delivery of a low-energy DC
shock for cardioversion of atrial fibrillation is very
effective.5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 With the presentation by
Liebold et al22 of the study of 100 consecutive
patients undergoing open heart surgery, we now have the demonstration
of a new clinical application of both the use of temporary epicardial
atrial wire electrodes and low-energy DC cardioversion of atrial
fibrillation. The article by Liebold et al22 is
actually about 2 things. One is a new therapeutic modality in the
treatment of atrial fibrillation in the period immediately after open
heart surgery. The other is the efficacy, safety, and tolerance of
so-called low-energy atrial defibrillation.
It is widely recognized that atrial fibrillation is a common and
important problem in patients who have had open heart surgery. As
recently summarized,23 many studies have examined
its potential cause(s), prevention, and treatment. Unfortunately,
although these studies have provided some insights, the problem has
abated little. Thus, according to the study by Liebold et
al,22 the demonstration of a new, effective
treatment, low-energy atrial defibrillation with temporary epicardial
wire electrodes placed on each atrium, is most welcome. The technique,
initially studied in an animal model,12 16 also
permits standard use of epicardial wire electrodes for
recording (diagnostic) and pacing (therapeutic and
diagnostic) purposes, just as the traditional temporary
epicardial atrial wire electrodes have been used in the
past.1 2 3 4 Nevertheless, use of this technique
does not change the problem, which is frequency of postoperative atrial
fibrillation. Rather, it offers a much easier way to provide DC
cardioversion of atrial fibrillation, when indicated, than the
traditional delivery of a transthoracic DC shock. Early or
late recurrence of atrial fibrillation notwithstanding, the
technique of low-energy atrial defibrillation with temporary epicardial
atrial wire electrodes should find a place in the standard treatment
regimen for atrial fibrillation after open heart surgery.
Perhaps the more important implications of the study by Liebold et
al22 pertain to the use of low-energy DC
cardioversion of atrial fibrillation with the implantable atrial
defibrillator. The use of an implantable atrial defibrillator system to
deliver low-energy shocks between special catheter electrodes
permanently placed in the right atrium and coronary sinus has
been under systematic study for many years, first in experimental
models and more recently in patients.5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 It is clear that
the device can be used successfully to defibrillate the atria in most
patients with paroxysmal or persistent atrial fibrillation. It is also
clear that if the shock is synchronized to ventricular
activation so that it is not delivered during the T wave of the
preceding QRS complex, something that the device has been reliably
programmed to do, the shock can be delivered
safely.15 16 22 24 The latter is possible in
large measure because cardioversion of atrial fibrillation is not an
emergency. Therefore, the device can wait for an R-R interval
that is long enough to permit the shock to be delivered to avoid
the T wave of the previous QRS complex. This has been demonstrated in
the first 51 patients studied systematically and followed up for
In sum, we should be encouraged by the data from the study by Liebold
et al22 in which low-energy shocks were delivered
directly to the atria to treat atrial fibrillation, in this instance by
use of temporary epicardial wire electrodes placed in patients after
open heart surgery. Besides providing data to support use of the
technique when appropriate in patients after open heart surgery, data
from the study by Liebold et al22 have the most
favorable implications related to wider application of the technique,
in which the implantable atrial defibrillator delivers shocks between
catheter electrodes placed in the right atrium and coronary
sinus. This is an exciting time in the study of atrial fibrillation.
The article by Liebold et al22 provides important
new data that have both practical clinical applications and yet wider
clinical implications.
Acknowledgments
Dr Waldo is supported in part by grant HL-38408 from the
National Institutes of Health; National Heart, Lung, and Blood
Institute; Bethesda, MD.
Footnotes
The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
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© 1998 American Heart Association, Inc.
Editorial
Low-Energy Atrial Defibrillation
A Promising New Technique
Key Words: Editorials • atrial defibrillation • open heart surgery • atrial fibrillation
6
months21 and continues to be demonstrated in the 
190
patients who have had the device implanted to
date.25 Thus, although efficacy and safety remain
important, and rigorous ongoing studies dealing with these issues need
to be completed, relevant data to date are encouraging. The third issue
is tolerance of the low-energy atrial defibrillation shock by the
patient. The results of the study by Liebold et
al22 demonstrate that delivery of the low-energy
shock is indeed tolerable without anesthesia. This is
consistent with other available data that indicate that
although delivery of the shock by the implantable atrial defibrillator
is associated with discomfort, the shock is indeed tolerable, with
patients willing to accept 
3 to 4 shocks per episode without the need
for anesthesia.20 21 26 27 28
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