| Objective:To evaluate and compare the value of methods in diagnosing and distinguishing orthodromic atrioventricular reciprocating tachycardia (OAVRT) using septal pathway from slow-fast atrioventricular nodal reentrant tachycardia(AVNRT).Materials and methods:All 47 patients were devided into 30 patients with slow-fast AVNRT and 17 patients with AVRT using concealed septal accessory pathway by ventricular extra-stimuli during tachycardia and His bundle refractory . All 47 patients underwent invasive electrophysiological studies,including the following 4 methods:1. Right ventricular stimuli in right midseptal and apex:'Right ventricular stimuli were introduced in right midseptal and apex with the same frequency (90-120bpm) in every patient during sinus rhythm,measured VA interval respectively.2. Para-Hisian PacingPara-Hisian Pacing was delivered during sinus rhythm with 90-120bpm . paid attention to the change of S-A interval while the QRS complex interval were changing.3. Right ventricular stimuli with the tachycardia cycle length:Right ventricular stimuli were given with the tachycardia cycle lengthwith HA during tachycardia.4. Right apical ventricular stimuli with interval 20ms less than the tachycardia cycle length during tachycardia:" Right apical ventricular stimuli were introduced with interval 20ms less than the tachycardia cycle length during tachycardia .observed the relationship between ventricular fusion and the change in AA interval. Results:Ventricular extra-stimuli duringtachycardia and Hisbundle refractory:A late ventricular extra-stimulus during tachycardia could advance the time of atrial activation over 20ms at the time when His bundle is refractory in 17 AVRT with concealed septal accessory pathway,terminate the tachycardia in 6 among the 17 patients;but could not advance the time of atrial activation(less than 10 ms) in 30 AVNRT,The way can distinguish and diagnose AVRT using concealed septal fast pathway from slow-fast AVNRT,sensitivity and specificity 100%.1. Right ventricular stimuli in right midseptal and apex:Right ventricular stimuli were given in right apex and midseptal with the same frequency during sinus rhythm,VAapex -VABase:-37+ 19ms in AVNRT,32+ llms in AVRT. The difference was significant,P< 0.01. Each difference was above 10ms in AVRT',below 10ms in AVNRT,no overlap was found. The way can distinguish and diagnose AVRT using concealed septal fast pathway from slow-fast AVNRT,sensitivity and specificity 100%.2. Para-Hisian Pacing:Surface QRS complex showed narrow or wide among 26/30 AVNRT and 13/15 AVRT with septal concealed pathway during para-Hisian Pacing . Wide QRS complex S-A interval:170+24ms,narrow QRS cpmplex S-A interval:102 +28ms,there were significant difference between wide and narrow QRS S-A interval,P<0.05,each wide QRS complex S-A interval was longer than each narrow QRS complex S-A interval with the same atrial activation in every AVNRT. Among 13/15 patients with AVRT,wide QRS complex S-A:134 + 10ms,narrow QRS complex S-A 110 + 25ms,there was no significant difference,P>0.05. While QRS interval was changing,the atrial activation were not changing and S-A interval remained unchanged or changed slightly (0-8) ms among 8/13 patients with AVRT. Para-Hisian Pacing can distinguish and diagnose AVRT using concealed septal fast pathway from slow-fast AVNRT,sensitivity 61.5%,specificity 100%.3. Rright ventricular stimuli with the tachycardia cycle length:Right ventricular stimuli were given with the tachycardia cycle length during sinus rhythm,H wave could not be found or verified during pacing . VA:176+47ms;HA PSVT:103 +58,HApsvr -VA pace:-70+ 32ms in AVNRT patients. VA:128 + 36ms;HA PSVT:171 + 42ms;HA PSVT -VA pace:43 + 42ms in AVRT patients . The difference(HA PSVT -VA pace) was significant between AVRT and AVNRT,P< 0.01,but there was some overlap between AVNRT and AVRT .The way could not completely distinguish AVNRT and AVRT .4. Right apical ventricular stimuli with interval 20ms less than the tachycardia cycle length d...
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