Objective : To observe the electrophysiological effects of sotalol on patients with atrioventricular accessory pathway and examine the function of sotalolin radiofrequency current ablation (RFCA)- Methods : Eighteen patients (8 males and 10 females , aged 15 ～69 years with a mean of 39-8) with atrioventricular accessory pathway including 14 cases ofleft pathway (2 dominant and 12 recessive) and 4 of right pathway (2 dominant and 2 recessive) were studied- Seldinger′s method was used to introduce catheter electrodes through rightinternaljugular vein and rightfemoral vein into the coronary sinus (CS) , high right atria (HRA) , His bundle (HRE) and right ventricular apex ( RVA)- After conventional intracardiac electrophysiological examination , 160 mg of sotalol were orally administered ,and electrophysiological parameters were then measured five times in succession at intervals of 30 minutes- Results : No significant change was found in P A, P R, A H, H Vand QRSintervals- Bradycardia occurred in 8 cases ,but vertigo ,fatigue and other symptoms were not observed- The effective refractory periods (ERP) of most of the patients were increased after oral administration of sotalol, as evidenced by the following pairs of electrophysiological data collected before and afterthe sotalol administration :sinus node recovery time (SNRT) ,1 165 ±209 ms vs- 1 456 ±371 ms ( p < 0-05) ;sinus cycle length (SCL) ,724 ±116 ms vs- 996 ±178 ms ( p < 0-05) ;atrial ERP, 211 ±24 vs- 243 ±36 ms ( p < 0-05) ;ventricular ERP,205 ±11 ms vs- 242 ±28 ms ( p < 0-05) ;anterograde ERPof the atrioventricular node , 269 ±48 ms vs- 343 ±97 ms ( p < 0-05) ;anterograde ERPofthe accessory pathway ,263 ±45 ms vs- 400 ±160 ms ( p < 0-05) ;retrograde ERP of the accessory pathway ,232 ±37 ms vs- 289 ±50 ms ( p < 0-05) ;tachycardia cycle , 323 ±49 ms vs- 382 ±25 ms ( p < 0-05) ;tachycardiainducing belt,66 ±20 ms vs- 30 ±17 ms ( p < 0-05) ;self termination percentage of induced tachycardia , 67 % ; QTinterval when the atria was stimulated atthe rate of100 times/ min ,339 ±31 ms vs- 364 ±27 ms ( p < 0-05)- In 3 cases ,atrial eletrical stimulation induced atrialfibrillation , but the patients were converted to sinus rhythm 30 minutes after administration of 160 mg sotalol ,and atrial electrical stimulation no longer resulted in atrial fibrillation- In one of the 3 cases , RFCA had to be abandoned in the first attempt because of repeated atrial fibrillation , however in the second attempt ,after 160 mg of oral sotalol ,no atrial fibrillation was induced and RFCA was successful- In 2 cases the induced AVRT was hard to be terminated by rapid electrical stimulation ,butit automatically terminated atthe anterograde of atrioventricular node and was no longerinduced 40 minutes after oral sotalol- RFCA was successfully applied to all ofthe 18 patients under study- A10 to 18 months follow up showed no recurrence- Conclusion : Oral administration of 160 mg of sotalol can increase the ERP of the accessory pathway in both anterograde and retrograde conduction, without blocking conduction of the accessory pathway- When used in RFCA,it can remarkably increase the patient′s endurance , effectively prevent or terminate atrial fibrillation induced by electrical stimulation- Additionally , the use of sotalol in RFCA does not affect the judgement ofthe effect of RFCAon the accessory pathway- Objective: To observe the electrophysiological effects of sotalol on patients with atrioventricular accessory pathway and examine the function of sotalolin radiofrequency current ablation (RFCA) -Methods: Eighteen patients (8 males and 10 females, aged 15-69 years with a mean of 39- 8) with atrioventricular accessory pathway including 14 cases ofleft pathway (2 dominant and 12 recessive) and 4 of right pathway (2 dominant and 2 recessive) were studied - Seldinger’s method was used to introduce catheter electrodes through right internaljugular vein and right femoral vein into the coronary sinus (CS), high right atria (HRA), His bundle (HRE) and right ventricular apex (RVA) - after conventional intracardiac electrophysiological examination, 160 mg of sotalol were orally administered, and electrophysiological parameters were then measured five times in succession at intervals of 30 minutes- Results: No significant change was found in PA, PR, AH, H Vand QRS intervals- Bradycardia occurred in 8 cases, but vertigo, fatigue and other symptoms were not observed - The effective refractory periods (ERP) of most of the patients were increased after oral administration of sotalol, as evidenced by the following pairs of electrophysiological data collected before and afterthe sotalol administration: sinus node recovery time (SNRT), 1 165 ± 209 ms vs- 1 456 ± 371 ms (p <0-05); sinus cycle length (SCL), 724 ± 116 ms vs-996 ± 178 ms <0-05); atrial ERP, 211 ± 24 vs-243 ± 36 ms (p <0-05); ventricular ERP, 205 ± 11 ms vs-242 ± 28 ms atrioventricular node, 269 ± 48 ms vs-343 ± 97 ms (p <0-05); anterograde ERPofthe accessory pathway, 263 ± 45 ms vs-400 ± 160 ms (p <0-05); retrograde ERP of the accessory pathway , Tachycardia cycle, 323 ± 49 ms vs-382 ± 25 ms (p <0-05); tachycardia induction belt, 66 ± 20 ms vs-30 ± 17 ms (p <0-05); self termination percentage of ind uced tachycardia, 67%; QTinterval when the atria was stimulated atthe rate of 100 times / min, 339 ± 31 ms vs.-364 ± 27 ms (p <0-05) - In 3 cases, atrial eletrical stimulation induced atrial fibrillation, but the patients were converted to sinus rhythm 30 minutes after administration of 160 mg sotalol, and atrial electrical stimulation no longer resulted in atrial fibrillation- In one of the 3 cases, RFCA had to be abandoned in the first attempt because of repeated atrial fibrillation, however in the second attempt, after 160 mg of oral sotalol, no atrial fibrillation was induced and RFCA was successful- In 2 cases the induced AVRT was hard to be terminated by rapid electrical stimulation, butit automatically terminated atthe anterograde of atrioventricular node and was no longer induced 40 minutes after oral sotalol- RFCA was successfully applied to all of the 18 patients under study- A10 to 18 months follow up showed no recurrence- Conclusion: Oral administration of 160 mg of sotalol can incr ease the ERP of the accessory pathway in both anterograde and retrograde conduction, without blocking conduction of the accessory pathway- When used in RFCA, it can remarkably increase the patient’s endurance, effectively prevent or terminate atrial fibrillation induced by electrical stimulation- the use of sotalol in RFCA does not affect the judgment of the effect of RFCAon the accessory pathway-