Further evidence for the site of reentry in so-called sinus node reentrant tachycardia in man.

To provide further evidence for the participation of the sinus node in so-called sinus node reentry in man, right atrial stimulation and endocardial mapping were performed in a case with sustained tachycardias which met the commonly accepted criteria for sinus node reentry. In addition to right atrial mapping, the activation of the high left atrium was depicted from the right pulmonary artery. The results clearly showed that in this patient the high right atrium was indeed the site of origin of the atrial echo beats which could be elicited by programmed premature atrial stimulation. The high left atrial electrogram (from the right pulmonary artery) was activated 35 msec after the high right atrium thus excluding the possibility of reentry in Bachmann's bundle. Atrial mapping during echo beats revealed a right atrial activation pattern which was similar to that observed during spontaneous sinus rhythm. Sinus node reentrant beats could also be evoked by programmed premature stimulation of the low lateral right atrium. In conclusion, activation of the high right atrium prior to the high left atrium is an important additional criterion for defining sinus node reentry in man. Thus, the recording of the left atrial signals from the right pulmonary artery helps to exclude reentry in the high left atrium, e.g. Bachmann's bundle.