(Circulation. 1999;100:e143.)
© 1999 American Heart Association, Inc.
Circulation Electronic Pages |
Professor of Medicine The George Washington University, Washington, DC
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I read with interest the article on the treatment of patients who have sick sinus syndrome (SSS) with single-chamber atrial pacing by Anderson et al.1 However, their finding of the annual risk of second- or third-degree atrioventricular (AV) block of only 0.6% per year contrasts somewhat with the reported findings that abnormal AV conduction was demonstrated in 57% to 67% of patients with SSS using invasive electrophysiologic techniques.2 3 4 Therefore, although Anderson et al1 demonstrated that abnormalities of AV conduction cause clinical problems only infrequently, it should be clear that a significant number of patients with SSS cannot be treated with atrial pacing alone. In these cases, dual chamber pacing (DDD or DDI, preferably with rate adaptation) should be the treatment of choice because the atrial transport function is then preserved.
The choice should not be restricted to dual-chamber versus
single-chamber atrial pacing only. Another viable option in the
treatment of SSS in these patients is ventricular pacing,
which was first reported in 1968.5 Ordinarily, pacing from
a ventricular site would not be expected to affect atrial
ectopic activity. However, after successful ventricular
capture following transvenous catheter pacing, atrial
tachyarrhythmias often no longer recur. Two
explanations can be offered. First, the improvement of atrial function
through improved coronary circulation secondary to the
restoration of an effective regular ventricular rhythm may
favorably affect the stimulation and fibrillation threshold of the
atria.5 Second, ventricular pacing causes
constant retrograde depolarization of the AV node and the atria and, by
suppressing the
Department of Cardiology, Skejby Sygehus, Aarhus University Hospital, Aarhus, Denmark
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