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@#Objective To determine the effects of resecting the lower half of left stellate ganglion (LSG) on fast ventricular rate (VR) in persistent atrial fibrillation (AF) and its mechanism. Methods Twelve mature healthy male beagle dogs (15–25 kg) were studied. They were randomly divided into two groups (an experimental group and a control group, 6 dogs in each group). The control group were merely performed with rapid left atrial pacing to induce persistent AF. The experimental group were disposed with rapid left atrial pacing and received resection of the lower half of LSG after the persistent AF was documented. Simultaneously the ventricular rates were monitored separately before anesthesia, after anesthesia, 30 minutes and one month after LSG resection. The forward passing effective refractory period (ERP) of the canine atrioventricular node (AVN) was also measured. Results Each dog was documented with persistent AF after 3–6 weeks’ left atrial pacing. After resecting the lower half of LSG for 30 minutes (the control group was only observed for 30 minutes without LSG resection), the average VR of the control group attained 144.5±4.2 beats/min, while that of the experimental group was 121.5±8.7 beats/min (P<0.001). After resecting the lower half of LSG for one month (the control group was observed for one month without LSG resection), the average VR of the control group was 139.2±5.6 beats/min, while that of the experimental group was 106.5±4.9 beats/min (P<0.001). Meantime, the forward passing ERP of AVN of the experimental group was significantly prolonged than that of the control group (265.6±7.8 msvs.251.1±4.6 ms, P=0.003). Conclusion Resection of the lower half of LSG is efficient in reducing VR in canines with persistent AF, one of the mechanisms of which may be prolonging the forward passing ERP of AVN.
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Aim To investigate the effect of taurine-magnesium coordination compound (TMCC) on elec-trocardiogram of isolated guinea pig hearts, hoping to describe a primary research on its characteristic of anti-short QT syndrome. Methods The isolated guinea pig heart was retrograde perfused using Langendorff tech-nique. In order to determine the effects of TMCC on QT interval, transmural dispersion of repolarization, effective refractory period, instability of RR interval and instability of QT interval in the presence of potassi-um channel opener pinacidil, the electrocardiogram of isolated guinea pig hearts was recorded using Biopac physiological recorder. Results The shortened QT in-terval and the effective refractory period induced by pinacidil could be prolonged by TMCC; the increased transmural dispersion of repolarization induced by pinacidil could be decreased by TMCC; the increased instability of RR and QT interval induced by pinacidil could be decreased by TMCC. Conclusion TMCC has the effects of anti-SQT2 by prolonging the QT inter-val and the effective refractory period, reducing the transmural dispersion of repolarization and instability.
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Objective To investigate the effects of circumferential pulmonary vein isolation (CPVI) on atrial effective refractory period (ERP) in patients with paroxysmal atrial fibrillation.Methods 30 patients who underwent radiofrequency catheter ablation for paroxysmal AF were enrolled in this study.Using FAM mode,the RA and LA anatomical models were achieved in the CARTO 3 system.SVC,MRA,RAA,LA-A,LA-R,LA-P,LAA,LSPV,LIPV,RSPV,RIPV,CSp,CSd,were respectively located in the RA or LA anatomical model.Before and after CPVI,ERPs were measured in different locations of the atrium using programmed stimulation.The ERPs of the RA (SVC,MRA,RAA,CSp),LA (LA-A,LA-R,LA-P,LAA,CSd),PVs (LSPV,RSPV,LIPV,RIPV) were compared.Bilateral CPVIs were completed in all patients,and PV-LA bidirectional conduction block was achieved.The changes of electrophysiological characteristics of atrium before and after CPVI were observed.Results (1) ERP at different locations in the atrium before CPVI:Comparisons of ERPs at different locations of atrium:RAA had the minimal ERPs[(197.4 ± 28.6) ms (P ＜ 0.01);followed by PVs measuring,respectively,LSPV (213.0 ± 47.5) ms,LIPV (208.9 ± 45.9) ms,RSPV (209.3 ± 43.6) ms,RIPV (213.5 ± 48.1) ms and LAA (218.1 ± 27.7) ms.Comparisons of ERPs in RA,LA,and PVs showed:PVs had the lowest ERPs (211.2 ± 35.2) ms versus RA ERP (227.0 ± 23.7) ms versus LA ERP (241.0 ± 21.5) ms (P ＜ 0.05).(2) Comparisons of ERPs before and after CPVI:Comparisons of ERPs at different locations of atrium showed:RAA [(197.4 ± 28.6) ms vs.(208.6 ± 32.2) ms,P=0.003],CSp [(234.7 ± 29.1) ms vs.(246.9 ± 29.7) ms,P=0.007],LA-R [(242.9 ± 28.9) ms vs.(258.3 ± 26.9) ms,P=0.003],LA-P [(252.2 ± 28.5) ms vs.(261.1 ± 30.2) ms,P=0.039]and CSd [(238.6 ± 28.3) ms vs.(250.3 ± 23.6) ms,P =0.009].ERPs were found statistically prolonged at all different locations after CPVI.Comparisons of ERPs at RAand LA after CPVI showed:RA [(227.0 ± 23.7) ms vs.(235.9 ± 21.7)ms,P=0.002]and LA [(241.0 ± 21.5) ms vs.(249.7 ± 19.9) ms,P =0.001],which were statistically increased after CPVI.(3) A total of 90 episodes of atrial arrhythmias were induced before CPVI which were found at RAA (n =17),LAA (n =12),and PVs (n =36).After CPVI,8 episodes of atrial arrhythmias were induced which were found at,RAA (n =4),LAA (n =3),and SVC (n =1).Conclusions (1) Compared with other parts of atrium,ERPs at PVs,LAA and RAA are significantly shorter in patients with paroxysmal AF.At PVs,LAA and RAA,atrial arrhythmias are easily to be induce by programmed stimulation.(2) In patients with paroxysmal Af:PVs has the shortest ERPsfollowed by RAs whereas LA ERPs is the longest.There is a large ERP gradient change between PVs and LA.(3) The ERPs at RAs,LAs,As,and LA-PV are prolonged after CPVI.(4) Atrial arrhythmia is less likely to be induced after CPVI.
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Objective To introduce a new method of local denervation by ablation and to observe its effect on ventricular effective refractory periods and ventricular arrhythmia susceptibility after acute myocardial infarction. Methods Eighteen mongrel dogs were used to make myocardial infarction model by ligation of the 1st diagonal artery. Then local denervation was achieved by using six radiofrequency ablations (each at 8 W for 2 min) along the left anterior descending artery. Effective refractory periods were tested at six sites on the left ventricular epicardium (above, in and below the infarction areas, 2 sites each area) before and after local denervation by S1S2 stimulation. Ventricular arrhythmia was also induced after myocardial infarction and after denervation by burst pacing, and the number of arrhythmia episodes was recorded. Results The effective refractory periods were significantly prolonged after ablation ([191. 3±24. 9] ms vs [209. 0±27. 2] ms, P<0. 05). And the prolongation of effective refractory periods in infarcted area ([11. 3±8. 8] ms) was significantly shorter than those in the other 2 areas ([23. 2±10. 2] ms and [18. 7±11. 5] ms). After ablation, 8 of the 11 susceptible dogs were free of induced ventricular arrhythmia, while 3 of them were still inducible by burst pacing. The induced ventricular arrhythmia rate was reduced from 61.1% (11/18) to 16.7 %(3/18) (P = 0. 007). Conclusion The method in this study is promising for preventing ventricular arrhythmia in patientswith acute myocardial infarction receiving percutaneous coronary intervention.
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Objective To explore the effect of ablation of left superior pulmonary vein fat pad(LSPV-FP) on atrial fibrillation(AF). Methods Twelve healthy adult mongrel dogs were anesthetized and ventilated; both cervical vagosympathetic trunks were exposed for stimulation. Thoracotomies at the 4th intercostal space of left and right chest were performed to expose the LSPV-FP. The effective refractory period(ERP)/ERP-dispersion (dERP) of atrium and LSPV, AF inducibility, and the ventricular rate of AF were measured in the following statuses: baseline, vagosympathetic trunk stimulation(VTS), LSPV-FP ablation, and VTS post LSPV-FP ablation. Results At baseline status, stimulation of the left or right vagosympathetic trunks significantly shortened the ERP of atrial ([84.44±29.50] ms vs [129.7±15.83] ms, [85.42±26.11] ms vs [129.7±15.83] ms, P<0.05), increased the dERP of atrial ([71.67±14.03] ms vs [34.17±18.32] ms, [57.5±24.17] ms vs [34.17± 18.32] ms, P<0.05), the difference of ERP between proximal and distal of LSPV(P<0.05), AF inducibility ([5.33± 1.231] times vs [0.75±0.96] times, [4.67±1.155] times vs [0.75±0.96] times, P<0.05), and deceased the ventricular rate of AF([143.6±22.42] beats/min vs [226.3±28.50] beats/min, [146.4±30.72] times/min vs [226.3±28.50] times/ min, P<0.05). LSPV-FP ablation significantly attenuated all the above electrophysiological changes induced by left VTS(P< 0.05), but showed no effects on those induced by right VTS. Conclusion Left vagosympathetic trunk plays an important role in the development and maintenance of AF partially through LSPV-FP.
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Objective Toexplore the effect of ablation of left superior pulmonary vein fat pad (LSPV-FP) on atrial fibrillation(AF). Methods Twelve healthy adult mongrel dogs were anesthetized and ventilated; both cervical vagosympathetic trunks were exposed for stimulation. Thoracotomies at the 4th intercostal space of left and right chest were performed to expose the LSPV-FP. The effective refractory period(ERP)/ERP-dispersion (dERP) of atrium and LSPV, AF inducibility, and the ventricular rate of AF were measured in the following statuses: baseline, vagosympathetic trunk stimulation(VTS), LSPV-FP ablation, and VTS post LSPV-FP ablation. Results At baseline status, stimulation of the left or right vagosympathetic trunks significantly shortened the ERP of atrial ([84. 44±29.50] ms vs [129. 7± 15. 83] ms, [85. 42±26. 11] ms vs [129. 7± 15. 83] ms, P<0. 05), increased the dERP of atrial ([71. 67 ± 14. 03] ms vs [34. 17 ± 18. 32] ms, [57. 5 ± 24. 17] ms vs [34. 17 ± 18.32] ms, P<0. 05), the difference of ERP between proximal and distal of LSPV(P<0. 05), AF inducibility ([5. 33± 231] times vs [0. 75±0. 96] times, [4. 67± 1. 155] times vs [0. 75±0. 96] times, P<0. 05), and deceased the ventricular rate of AF([143. 6±22. 42] beats/min vs [226. 3±28. 50] beats/min, [146. 4±30. 72] times/min vs [226. 3±28. 50] times/ min, P<0. 05). LSPV-FP ablation significantly attenuated all the above electrophysiological changes induced by left VTS(P< 0. 05), but showed no effects on those induced by right VTS. Conclusion Left vagosympathetic trunk plays an important role in the development and maintenance of AF partially through LSPV-FP.
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The effect of acute ischemia on the electrophysiological characteristics of the three layers myocardium of canine in vivo was investigated. Twelve canines were divided into two groups randomly: acute ischemia (AI) group and sham operation (SO) group. By using the monophasic action potential (MAP) technique, MAP and effective refractory period (ERP) of thethree layers myocar dium were measured by specially designed plunge needle electrodes and the transmural dispersion of repolarization (TDR) and transmural dispersion of ERP (TDE) were analyzed. The results showed that in the AI group, MAP duration (MAPD) was shortened from 201.67±21.42 ms to 169.50±13.81 ms (P＜0.05), but ERP prolonged to varying degrees and TDE increased during ischemia.In the SO group, MAPD and ERP did not change almost. Among of the three layers myocardium of canine, MAPD was coincident in two groups. It was concluded that during acute ischemia, MAPD was shortened sharply, but there was no significant difference among of the three layers myocardium. The prolonged ERP was concomitant with increased TDE during acute ischemia, which may play an important role in the occurrence of arrhythmias induced by acute ischemia. These findings may have important implications in arrhythmogenesis.
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AIM To study the effects of matrine (Ma) on the action potential and contractile force in guinea pig papillary muscles. METHODS Conventional microelectrode technique was used to record the fast action potentials (FAP) and slow action potentials (SAP) induced by histamine and BaCl_2 of guinea pig papillary muscles. RESULTS Ma 10,25,50 ?mol?L -1 dose-dependently prolonged the action potential duration at 50%, 90% repolarization (APD_ 50 , APD_ 90 ) and effective refractory period (ERP) of FAP, and lengthened the APD_ 50 , APD_ 90 of SAP induced by histamine and BaCl_2 when perfused with KCl 25 mmol?L -1 Tyrode's solution. The maximal upstroke velocity (V_ max ) of FAP, SAP and contractile force (Fc) were not affected by matrine 10,25,50 ?mol?L -1 . CONCLUSION It was suggested that Matrine could block K + channels in the myocardium.-
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AIM To study the mechanism of puerarin against arrhythmias. METHODS Standard microelectrode intracellular recording technique was used RESULTS ①Puerarin 0 005, 0 01,0 015 mmol?L -1 prolong the action potential duration at 50% and 90% of repolarization (APD 50 ,APD 90 ) respectively APD 50 was prolonged from (176 43?51 37) ms to (192 86?60 82) ms ( n=7, P
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Objectives To evaluate the safety of intravenous amiodarone in patients with atrial fibrillation and rapid ventricular response via an accessory pathway. Methods Sixteen patients with Wolff Parkinson White syndrome (W P W group) and 16 patients with concealed accessory pathway (control group) were included. The anterograde effective refractory period of accessory pathway (ERP AP ) in W P W group and the effective refractory period of atrioventricular node (ERP AVN ) in control group were measured. Then 150mg of amiodarone was injected intravenously in 10min, the ERP AP and ERP AVN were remeasured 10min later. Results After amiodarone injection, ERP AP was increased slightly ( P