Clinical Analysis Of Dual Atrioventricular Nodal Pathways Induced Atrioventricular Block

Background and Objective:Dual atrioventricular node pathway(Dual Atrioventricular Nodal Pathway,DAVNP)means that there are two conduction pathways with different performance in atrioventricular node,which are functionally separated longitudinally,and their refractory period and conductivity are different.therefore,reentrant and non-reentrant tachycardia can be produced in clinic,and the electrocardiographic manifestations are various.Even due to occult conduction,atrioventricular block(Atrioventricular block,AVB)occurs in sinus rhythm,which needs to be carefully screened,otherwise it is easy to be misdiagnosed and even lead to unnecessary pacing treatment.This paper reports 11 patients with atrioventricular block diagnosed by intracardiac electrophysiology with dual atrioventricular node pathway and sinus rhythm,and successfully returned to normal atrioventricular block after modified slow pathway.the clinical and electrophysiological characteristics of atrioventricular block in sinus rhythm were summarized.Objects and methods:A total of 11 patients were selected from the second affiliated Hospital of Nanchang University from January 2012 to December 2019.there were 9 males and2 females,aged 12 ~ 45(mean age 22 ± 9 years)and 9 cases of paroxysmal palpitation.4 cases had typical tachycardia and showed sudden stop,and 2 cases had no obvious symptoms.The examination of electrocardiogram,24-hour ambulatory electrocardiogram or 10-day long-term ambulatory electrocardiogram showed that sinus rhythm time intermittent I degree and II degree atrioventricular block,the longest P-R was 660 ms,and continuous atrioventricular block occurred at 2:1 in the most serious cases.There was no history of heart disease,hypertension and other diseases,and there was no obvious history of upper respiratory tract infection and drug use before treatment.Cardiac color ultrasound or MRI exclusive structural heart disease,exclusive thyroid disease and electrolyte disorder.All patients signedinformed consent and underwent intracardiac electrophysiological examination and radiofrequency ablation after definite diagnosis.24-hour ambulatory electrocardiogram and 10-day long-term ambulatory electrocardiogram were reexamined after operation.The patients were followed up for 3 months to 3 years,and the atrioventricular block was observed.Results:(1)Atrioventricular conduction abnormalities frequently occurred in all patients during electrophysiological examination,and the block site was above his bundle.The A-V interval was significantly prolonged,the A-H interval was suddenly or gradually prolonged,but the HV interval remained unchanged,and the atrioventricular conduction function of intravenous isoproterenol or atropine returned to normal.(2)After intravenous isoproterenol or atropine,typical atrioventricular nodal slow-fast reentrant tachycardia was induced by atrial program or incremental stimulation in 7 cases(figure 6),and typical atrioventricular nodal dual pathway jumping phenomenon was found in the other 4 cases(A-H suddenly extended120ms-210 ms,figure 7),of which 3 cases had jump and echo.After the slow pathway of atrioventricular node was improved in all patients,the abnormal atrioventricular conduction and jumping phenomenon disappeared.(3)During the follow-up of 3 months to 3 years,there was no palpitation and other symptoms.Atrioventricular block was not recorded in 24-hour ambulatory electrocardiogram and 7-day long-term ambulatory electrocardiogram.Conclusion:Atrioventricular block in young people with sinus rhythm may not always have Atrioventricular node dysfunction.Clinically,it should be carefully screened and alert to AVB caused by occult conduction caused by the DAVNP.The atrioventricular node slow path improvement can completely return to normal.