Accessory atrioventricular pathway, supra-, and infrahisian conduction impaired due to mitral annulus calcification

Disorders of conduction occurring simultaneously in both normal and accessory pathways of patients with Wolff-Parkinson-White (WPW) syndrome have only rarely been observed. To our knowledge this is the first report of impaired conduction in both pathways in WPW syndrome due to mitral annulus calcification (MAC). This case of WPW syndrome type A presented the following conduction abnormalities: (1) right bundle-branch block; (2) transient second-degree AV block with prolonged PR interval of the conducted beats; (3) during electrophysiological study, induction of tachycardia, dependent (phase 3) second-degree AV block, and occasionally conduction of two consecutive beats, the second showing an increased H-V interval (from 25 to 60 ms) and left bundle-branch block (LBBB) pattern, due to (4) infrahisian conduction abnormality.     

完全性左束支传导阻滞合并显著电轴左偏32例分析

本文对32例完全性左束支传导阻滞(CLBBB)合并显著电轴左偏超过(-30°)和20例CLBBB电轴正常两组病人进行对比观察。结果无论在心脏形态大小或心电图改变方面电轴左偏病人比电轴正常者病情严重。CLBBB合并电轴明显左偏的发病机制可以有五种情况解释。     

局部浸润和神经阻滞麻醉在会阴切开中的应用分析

目的 探讨会阴切开时不同麻醉方式对产妇的影响.方法 将100例产妇随机分为左侧阴部神经阻滞麻醉组(阻滞组)和局部组织浸润麻醉组(浸润组),每组50例,比较两组产妇镇痛效果、缝合时间、第四产程出血量及产后72h活动的情况.结果 浸润组在镇痛效果、缝合时间、出血量及产后的活动方面均优于阻滞组.结论 在会阴切开缝合术中应用小剂量利多卡因作阴部浸润麻醉有效减轻了产妇的切口疼痛,缩短缝合时间,减少第四产程出血量.     

房室传导阻滞的希氏束电图研究

研究了19例AVB的希氏束电图(HBE)。经皮穿刺股静脉将三极导管送至心脏希氏束部位,记录HBE。一度AVB5例,其中4例阻滞于房室结内,1例在希氏束内;二度AVB4例,3例阻滞于房室结,1例在希浦系;三度AVB10例,5例阻滞于房室结内,4例在希氏束,1例在希浦系。HBE能确定房室传导的阻滞部位,对指导安装起搏器和判断预后有一定意义。     

Block of the endplate acetylcholine receptor channel by the sympathomimetic agents ephedrine, pseudoephedrine, and albuterol

Recent observations suggest that some patients with congenital myasthenic syndromes respond favorably to ephedrine, pseudoephedrine, or albuterol. Conventional microelectrode studies, however, provide no clear explanation for a beneficial effect of ephedrine in endplate diseases. To gain further insight into how these drugs affect neuromuscular transmission, we investigated their effects on the kinetic properties of the acetylcholine (ACh) receptor. Single channel currents were recorded from rat lumbrical muscles endplates using low concentrations of ACh and 2.5–100 μM of drugs. Between 10–100 μM, each drug progressively increased the rate of channel closure in a concentration dependent manner, consistent with an open-channel block. Albuterol acted as a sequential fast-acting channel blocker, increasing the mean burst duration in a concentration dependent manner without altering the total open time per burst or the duration of intraburst blockages. Increasing concentrations of ephedrine and pseudoephedrine also increased the number of intraburst closures but decreased the total open time per burst. None of the drugs altered single channel conductance. The channel blocking effects of ephedrine and pseudoephedrine might reduce the synaptic overactivity that occurs in the slow-channel myasthenic syndromes or in endplate ACh esterase deficiency, but these effects occur at concentrations not attainable in clinical practice.     

Antibody Mediated Complete Congenital Heart Block in the Fetus

Complete congenital heart block (CCHB) affects 1:20,000–25,000 live births and is usually an atrioventricular block; 30–50% of fetuses with CCHB will have a structural anomaly, though recently attention has focused on the etiological influence of autoimmune disease, such as systemic lupus erythematosus. The diagnosis is established by detailed two-dimensional ultrasound scanning of the heart to exclude anomaly coupled with M-mode echocardiography and Doppler blood velocity patterns in the major vessels to detect the uncoupling of atrial and ventricular rhythms. Risk factors for an affected child are discussed. A previously affected child, high titers of anti-Ro antibodies, the presence of anti-Ro (SS-A) and anti-La (SS-B), and maternal HLA DR3 confer high risk. Antibody mediated CCHB is irreversible. Plasmapheresis and immunosuppression have been attempted in affected mothers, with limited success, to reduce the likelihood of the fetus being affected, and steroids have been used to reduce the inflammatory reaction in the heart. In many cases the underlying pathology of the immune system adversely affects utero-placental function requiring careful monitoring of fetal well-being. CCHB renders fetal heart rate monitoring virtually useless, in the antenatal and intrapartum periods. Alternatives are explored.     

Effects of trapidil-derivatives on calcium channel currents in isolated ventricular cells from mice

Summary A single glass micropipette voltage clamp technique with intracellular dialysis was used to study the effects of the trapidil derivatives AR 12–456 and AR 12–463 on Ca channel currents carried by Bat+ in isolated ventricular cells from mice hearts. Inspite of a more potent inhibition of the cAMP phosphodiesterase from heart (Bartel et al. 1985) a reversible Ca channel blocking action of both compounds could be observed. The concentration of half maximal block was calculated to about 50 mol/l for both derivatives tested. Neither a shift in the current-voltage relationships nor a significant change in the potential for half maximal activation was found. The maximal Ba²⁺ -conductance was reduced. The steady state inactivation was shifted towards more negative potentials by application of 100 mol/l AR 12–463. The decay of the Ba currents was accelerated in the range of the applied test potentials between –20 and +20 mV. It is concluded that the new trapidil derivatives with more potent inhibitory action on cardiac phosphodiesterase than trapidil can block myocardial Ca channels. Send offprint requests to B. Nilius     

前锯肌平面阻滞和胸椎旁神经阻滞在胸腔镜手术中的麻醉效果及对疼痛因子的影响

目的 研究前锯肌平面阻滞与胸椎旁神经阻滞对胸腔镜手术患者的麻醉效果及对疼痛因子的影响。方法 选取2020年11月—2021年9月安徽省池州市人民医院60例接受胸腔镜手术治疗的患者作为研究对象,按照随机数字表法分为A组和B组,每组30例。两组患者术中均接受气管插管全身麻醉,麻醉诱导前,A组选择前锯肌平面阻滞,B组选择胸椎旁神经阻滞。比较两组患者的麻醉效果、阻滞操作时间、阻滞起效时间、阻滞持续时间、生命体征、术后镇痛泵按压次数、术后舒芬太尼使用量、疼痛因子、术后疼痛评分及术后不良反应发生率。结果 A组的麻醉优良率为96.67%,B组的麻醉优良率为93.33%,两组比较,差异无统计学意义（P>0.05）。两组患者的麻醉平面、阻滞起效时间比较,差异无统计学意义（P>0.05）;A组较B组阻滞操作时间缩短,阻滞持续时间延长。两组患者切皮前后收缩压、舒张压、心率差值比较,差异无统计学意义（P>0.05）。A组的术后48 h内镇痛泵按压次数、术后舒芬太尼使用量较B组减少（P <0.05）。两组患者手术前后血清PGE2、IL-6差值比较,差异有统计学意义（P <0.05）...     

Influence of sinus impulses on the parasystolic cycle length

Recently, it has been shown that in most clinical cases of parasystole, the parasystolic rhythm is not completely independent of the sinus rhythm. In this study, to disclose the mechanism of such "irregular" parasystole, parasystolic cycles with an intervening sinus QRS complex (XSX) were compared with their immediately adjacent pure parasystolic cycles without any intervening nonparasystolic QRS complexes (XX) in 10 cases of ventricular parasystole. In eight cases, the XSX interval was equal to or nearly equal to the adjacent pure XX interval; in one, the XSX interval was shorter than the XX interval; and in only one, the XSX interval was longer than the XX interval. In six cases in which the XSX interval was almost equal to the XX interval, calculated XSX intervals with a later intervening sinus QRS complex were obtained from the differences between the XSSX interval (ie, interectopic interval with two intervening sinus QRS complexes) and its adjacent XX interval. In five of the six cases, the calculated XSX interval was shorter than the XX interval. These observations suggest that in most cases of parasystole, early intervening sinus impulses do not change the parasystolic cycle, whereas late intervening sinus impulses shorten the parasystolic cycle. This suggests the presence of type I second-degree entrance block as the mechanism of "irregular" parasystole.