A noninvasive transesophageal signal averaging technique for detection of sinus node electrogram

We have developed a noninvasive transesophageal signal averaging technique for direct recording of sinus node electrogram. In this study, sinus node e lectrograms were recorded from 106 of 138 patients (77%), comparable to tha t (46%) recorded by conventional transesophageal technique, 59 were male an d 47 were female ranging in age from 10-74 years (mean 44.2 +/- 12.4 years) . The signals from lead I, surface averaged lead and esophagus averaged lea d were amplified (up to 100 mu V/cm), filtered (0.1-50 Hz), AD converted to 16-bit accuracy at a sampling rate of 2 KHz and averaged by using the thre e channel low-noise amplifier. The signal averaged esophageal sinus node po tentials are deflections of low-amplitude and low-frequency preceding the P wave. Two morphologies, the domed wave (64 of 106 patients, 60%) and the s mooth upstroke slope (42 of 106 patients, 40%), can be seen. The directly r ecorded sinoatrial conduction time was 82.3 +/- 18.6 msec (mean +/- 2SD), r anged from 23-112 msec, amplitude was 3.8-27.7 mu V and dv/dt was 0.42-1.92 mV/sec. The sinoatrial conduction time recorded by the transesophageal cat heter technique was comparable to that (80.4 +/- 18.1 msec) recorded by the transvenous catheter method perfectly We think that signal averaged sinus node electrogram could be recorded in sinus rhythm in most patients with no rmal sinus node function and proper filter settings, high amplification and anti-drift technique are important in recording signal averaged esophageal sinus node electrogram.