Radiofrequency Catheter Ablation of AtypicalAtrioventricular Nodal Reentrant Tachycardia

Ablation of Atypical Atrioventricular Nodal Reentrant Tachycardia, Introduction: Published reports of radiofrequency ablation of atypical atrioventricular nodal reentranttacbycardia (AVNRT) have been limited. We present our experience in 10 consecutive patientswith atypical AVNRT wbo underwent radiofrequency ablation of the "slow" AV nodal pathway.
Methods and Resttlts: there were 9 females and 1 male; their mean age was 44 ± 19 years (± SD), the mean AVNRT cycle length and ventriculoatrial (VA) interval at the His positionduring AVNRT were 340 ± 50 msec and 200 ± 70 msec, respectively. the slow pathway wassuccessfully ablated in all patients with a mean of 10 ± 7 radiofrequency energy applications inthe posteroseptal right atritim near the coronary sinus os. The mean procedure duration was 100 ± 35 minutes. There were no complications. In 4 patients, target sites were identified during sinus rhythm by mapping for possible slow pathway potentials, In the other 6 patients, target sites were identified by mapping retrograde atrial activation during AVNRT or ventricularpacing, The VA times at successful target sites were a mean of 45 ± 30 msec less tban the VAtime at the His cathetcr during AVNRT, There were no differences in success rate, number ofradiofrequency energy applications, or procedure duration between patients in whom mappingwas guided by possible slow pathway potentials or by retrograde atrial activation, During 6 ± 3 months of followup, 1 patient bad a recurrence of atypical AVNRT and underwent a secondablation procedure, which was successful.
Conclusion: Radiofrequency ablation of atypical AVNRT can be safely and effectivelyaccomplisbed when target sites are identified based either on possible slow pathway potentialsduring sinus rbytbm or retrograde atrial activation times during tachycardia.     

Radiofrequency Ablation of Idiopathic Left Anterior Fascicular Tachycardia

Left Anterior Fascicular Tachycardia. Introduction: A 45-year-old man with idiopathic ventricular tachycardia (VT) having a right bundle branch block configuration with right-axis deviation underwent au electrophysiologic test.
Methods and Results: Mapping demonstrated a site on the auterobasal wall of the left ventricle where there was an excellent pace map and an endocardial activation time of -20 msec, hut radiofrequency catheter ablation at this site was unsuccessful. At a nearby site, a presumed Purkinje potential preceded the QRS complex by 30 msec during VT and sinus rhythm, and catheter ablation was effective despite a poor pace map and an endocardial ventricular activation time of zero.
Conclusion: Idiopathic VT with a right bundle branch configuration and right-axis deviation may originate in the area of the left anterior fascicle. A potential presumed to represent a Purkinje potential may he more helpful than endocardial ventricular activation mapping or pace mapping in guiding ablation of this type of VT.     

Differential Effect of Adenosine on Anterograde and Retrograde Fast Pathway Conduction in Patients with Atrioventricular Nodal Reentrant Tachycardia

Adenosine and Retrograde Fast Pathway Conduction . Introduction : Several studies have shown that the fast pathway is more responsive to adenosine than the slow pathway in patients with AV nodal reentrant tachycardia. Little information is available regarding the effect of adenosine on anterograde and retrograde fast pathway conduction.
Methods and Results : The effects of adenosine on anterograde and retrograde fast pathway conduction were evaluated in 116 patients (mean age 47 ± 16 years) with typical AV nodal reentrant tachycardia. Each patient received 12 mg of adenosine during ventricular pacing at a cycle length 20 msec longer than the fast pathway VA block cycle length and during sinus rhythm or atrial pacing at 20 msec longer than the fast pathway AV block cycle length. Anterograde block occurred in 98% of patients compared with retrograde fast pathway block in 62% of patients ( P < 0.001). Unresponsiveness of the retrograde fast pathway to adenosine was associated with a shorter AV block cycle length (374 ± 78 vs 333 ± 74 msec, P < 0.01), a shorter VA block cycle length (383 ± 121 vs 307 ± 49 msec, P < 0.001), and a shorter VA interval during tachycardia (53 ± 23 vs 41 ± 17 msec, P < 0.01).
Conclusion : Although anterograde fast pathway conduction is almost always blocked by 12 mg of adenosine, retrograde fast pathway conduction is not blocked by adenosine in 38% of patients with typical AV nodal reentrant tachycardia. This indicates that the anterograde and retrograde fast pathways may be anatomically and/or functionally distinct. Unresponsiveness of VA conduction to adenosine is not a reliable indicator of an accessory pathway.     

PERNICIOUS ANEMIA IN CHILDHOOD REPORT OF CASE IN SIX YEAR OLD GIRL RESPONDING TO REFINED LIVER EXTRACT, FOLIC ACID AND VITAMIN B12 IN SUCCESSIVE RELAPSES

A case of megaloblastic anemia without specific neurologic complications in a6 year old girl is presented as an example of pernicious anemia in childhood despitethe fact that a small amount of free hydrochloric acid was present in the gastricjuice after injection of histamine. Prompt hematologic response was obtained following administration of refined liver extract, folic acid and vitamin B₁₂ in successive relapses.

     

嘈杂语噪声下汉语整句识别的同质性研究

目的 获得嘈杂语噪声背景下汉语短句识别率一信噪比(Performance-Intensity,P-I)函数的斜率和50%的得分所对应的信噪比(记为SNR50),并对所有短句的同质性进行评估和调整.方法 采用16张(每张20句)新编嘈杂语噪声下汉语普通话短句识别表作为测试材料.选取年龄为21～25岁之间、听力/言语发育正常且日常以汉语普通话为交流方式的48名受试者按"随机区组设计"在-1、-4、-7、-10 dB四种信噪比条件下进行言语识别率的心理声学测量.使用Statistica7.0软件进行P-I函数拟合和统计分析.结果 320句语句在嘈杂语噪声下的言语识别P-I函数曲线的阈值呈正态分布,斜率呈不规则分布.剔除P-I函数强健性增长(斜率＞55%/dB)的语句,并保留阈值变异度在±2σ内的语句,精选出同质性良好的240句.结论 逐个调整每句的SNR以实现同质性,可为编制"等言语识别阈级"的句表奠定扎实的心理声学基础.     

Synthesis of phosphotyrosine-containing peptides by the solid-phase method

A practical and convenient procedure for making phosphotyrosine-containing peptides by the solid-phase method was developed. Phosphotyrosine was incorporated via Boc-Tyr(PO₃Bzl₂)-OH. The completed peptide was cleaved from the solid support by treatment with 1 M TMSBr-thioanisole-TFA. By gel-phase ³¹P-NMR spectroscopy we found that one of the benzyl protecting groups on phosphate was completely removed by two consecutive runs of Boc deprotection with 50% TFA-DCM. However, the other benzyl group remained intact throughout the synthesis (35 cycles).     

Quinidine single dose pharmacokinetics and pharmacodynamics are unaltered by omeprazole

Omeprazole has been shown in previous studies to inhibit the hepatic metabolism of selected drugs. Quinidine is an antiarrhythmic and antimalarial agent with a low therapeutic index. We therefore examined the effect of 40 mg omeprazole daily for one week or placebo on the pharmacokinetics and pharmacodynamics of a single 400 mg dose of quinidine in 8 healthy volunteers in a double-blind crossover study. During placebo and omeprazole treatment, there was no significant difference in area under the time-plasma quinidine concentration curve, (17.0 +/- 4.83 micrograms.h/ml, 18.6 +/- 4.43 micrograms.h/ml, respectively; P greater than 0.2) or renal clearance of quinidine (56.2 +/- 26.0 ml/min, 55.6 +/- 12.7 ml/min, respectively; P greater than 0.5). Quinidine unbound fraction in plasma (0.170 +/- 0.041 vs. 0.166 +/- 0.041 in the presence of omeprazole; P greater than 0.5) was not altered by omeprazole. Peak plasma quinidine concentration and the time this occurred did not differ. Omeprazole also had no effect on these parameters for the metabolite 3-hydroxyquinidine. There was no significant difference in the change in the corrected Q-T interval on the electrocardiogram due to quinidine (mean area under the time versus delta Q-Tc curve = 351 +/- 192 ms.h, placebo; 414 +/- 303 ms.h, omeprazole) showing that quinidine pharmacodynamics were unaltered by omeprazole. We conclude that omeprazole does not affect the pharmacokinetics of quinidine.     

Gender Differences in the Clinical Characteristics and Atrioventricular Nodal Conduction Properties in Patients With Atrioventricular Nodal Reentrant Tachycardia

Gender Differences in Patients With AVNRT. Introduction: The detailed electrophysiological characteristics of the gender differences associated with atrioventricular nodal reentrant tachycardia (AVNRT) have not been clarified. This study investigated the gender‐related electrophysiological differences in a large series of patients undergoing radiofrequency catheter ablation. Methods and Results: A total of 2,088 consecutive AVNRT patients (men/women 869/1,219) who underwent catheter ablation were enrolled in this study. We evaluated the gender differences in their electrophysiological characteristics. Women had a significantly younger age of onset, higher incidence of multiple jumps, shorter AH interval, atrial effective refractory period (ERP), anterograde fast pathway ERP, anterograde slow pathway ERP, and retrograde slow pathway ERP, and longer ventricular ERP than men. The incidence of baseline ventriculoatrial dissociation was lower in women than in men. Women needed less isoproterenol/atropine to induce AVNRT. No gender differences in the radiation exposure time, procedure time, complication rate, acute success rate, or second procedure rate were noted. Both typical and atypical AVNRT were more predominant in women. In the patients with atypical AVNRT, there was no significant gender difference in incidence of baseline ventriculoatrial dissociation; however, the retrograde slow pathway ERP was significantly shorter in women than in men. Women of premenopausal age (≤50 years old) had a significantly higher incidence of anterograde multiple jumps and a retrograde jump phenomenon, and a shorter anterograde slow pathway ERP and retrograde slow pathway ERP than those of women over 50 years old. Conclusion: Gender differences in the anterograde and retrograde AV nodal electrophysiology were noted in the patients with AVNRT. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1114‐1119)     

The Novel Electrophysiology of Complex Fractionated Atrial Electrograms: Insight from Noncontact Unipolar Electrograms

Unipolar Characteristics of CFAEs. Background: The noncontact mapping (NCM) system possesses the merit of global endocardial recording for unipolar and activation mapping. Objective: We aimed to evaluate the unipolar electrogram characteristics and activation pattern over the bipolar complex fractionated atrial electrogram (CFAE) sites during atrial fibrillation (AF). Methods: Twenty patients (age 55 ± 11 years old, 15 males) who underwent NCM and ablation of AF (paroxysmal/persistent = 13/7) were included. Both contact bipolar (32–300 Hz) and NCM virtual unipolar electrograms (0.5–300 Hz) were simultaneously recorded along with the activation pattern (total 223 sites, 11 ± 4 sites/patient). A CFAE was defined as a mean bipolar cycle length of ≤ 120 ms with an intervening isoelectric interval of more than 50 ms (Group 1A, n = 63, rapid repetitive CFAEs) or continuous fractionated activity (Group 1B, n = 59, continuous fractionated CFAEs), measured over a 7.2‐second duration. Group 2 consisted of those with a bipolar cycle length of more than 120 ms (n = 101). Results: The Group 1A CFAE sites exhibited a shorter unipolar electrogram cycle length (129 ± 11 vs 164 ± 20 ms, P < 0.001), and higher percentage of an S‐wave predominant pattern (QS or rS wave, 63 ± 13% vs 35 ± 13%, P < 0.001) than the Group 2 non‐CFAE sites. There was a linear correlation between the bipolar and unipolar cycle lengths (P < 0.001, R = 0.87). Most of the Group 1A CFAEs were located over arrhythmogenic pulmonary vein ostia or nonpulmonary vein ectopy with repetitive activations from those ectopies (62%) or the pivot points of the turning wavefronts (21%), whereas the Group 1B CFAEs exhibited a passive activation (44%) or slow conduction (31%). Conclusions: The bipolar repetitive and continuous fractionated CFAEs represented different activation patterns. The former was associated with an S wave predominant unipolar morphology which may represent an important focus for maintaining AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 640‐648, June 2010)