Alteration of Human Placental Vascular Tone by Antiarrhythmic Medications In Vitro

Antiarrhythmic and Placental Vessels. Introduction : Antiarrhythmic medications are commonly used during pregnancy for treatment of maternal or fetal arrhythmias, but little is known about their effect on human placental vascular tone and, consequently, placental blood flow. The objective of this study was to evaluate the tone responses caused by antiarrhythmic medications in human placental vessels from normal term pregnancies in vitro.
Methods and Results : Isolated human placental arteries and veins from uncomplicated term pregnancies incubated in Krebs'-bicarbonate under 5% oxygen/5% carbon dioxide/balance nitrogen (PO₂ 35 to 38 torr) were exposed to cumulative doses of quinidine, procainamide, lidocaine, flecainide, propranolol, amiodarone, verapamil, digoxin, and adenosine after submaximal contraction with 5-hydroxytryptamine. The study was conducted both in the presence and absence of endothelium. The addition of the tested medications caused a significant, dose-dependent relaxation of human placental arteries and veins except for adenosine, which induced a sustained, dose-dependent contraction of human placental vessels regardless of the presence or absence of tone. Removal of the endothelium did not alter these responses.
Conclusions : Based on these results, the medications tested should have no decremental effect on placental blood flow, with the possible exception of adenosine, which causes significant. dosedependent contraction of human placental vessels in vitro. Should similar contraction be present in vivo, it may have an adverse effect on the fetus when administering adenosine to pregnant women at term or during labor.     

旁道位置与室上性心动过速首次发作时年龄及性别的关系探讨

目的为了解旁道位置与室上性心动过速初次发作时年龄及性别的关系.方法对128例已进行过射频消融的患者进行了回顾性分析.结果男性左侧旁道发病时平均年龄大于右侧及中隔旁道平均为14岁和9岁;大于女性左侧旁道7岁,男性显性旁道发病时平均年龄小于隐匿性旁道7岁.而女性显性旁道与隐匿性旁道、左侧旁道与右侧旁道发病时平均年龄无显著性差异.结论旁道位置与室上速初次发作时年龄及性别有关.     

The effect of myocardial preservation technique on supraventricular tachycardia following aortic valve replacement

We studied 100 patients who underwent an isolated aortic valve replacement (AVR) between 1974 and 1991. The patients were divided into the following two groups and compared: group A, which consisted of 40 patients operated on before 1978 who underwent continuous left coronary perfusion with blood; and group B, which consisted of 60 patients operated on after 1979 in whom St. Thomas solution was used in combination with topical cardiac cooling. Moreover, we divided the group B patients into two subgroups: group Bl, who underwent AVR before 1986 during which we administered St. Thomas solution with ice slush every 30 min; and group B2, who had AVR after 1986 in which we used St. Thomas solution with a cold saline (4°C) solution and treated with a small amount of slushed ice every 15 min. The incidence of supraventricular tachycardias was 15% in group A, 50% in group BI, and 15% in group B2. The severity of preoperative New York Heart Association (NYHA) functional class, the type of valve lesions, cardiothoracic ratio, left ventricular function, aortic clamp time, bypass time, and use of drugs did not correlate with the incidence of supraventricular tachycardias in either group A or B. In group B2 patients, we paid a lot of attention to cooling the right atrium as well as the left ventricle by immersing the whole heart using a 4°C saline solution, which led to a remarkable reduction of the incidence of supraventricular tachycardia. This fact indicates that right atrial preservation is one of the most important factors for reducing the incidence of supraventricular tachycardia.     

Flecainide

Flecainide. Flecainide is a Class IC antiarrhythmic agent whose primary electrophysiologic effect is a slowing of conduction in a wide range of cardiac tissues. It is well absorbed and effective in suppressing isolated premature ventricular contractions (PVCs) or nonsustained ventricular arrhythmia but has only a modest efficacy when electrophysiologic testing is used as an endpoint. Us adverse effect on mortality in the CAST trial suggested a propensity to proarrhythmia-a phenomenon to which the Class IC agents appear particularly prone. Despite the applicability of the CAST study only to patients with a prior myocardial infarction, there has been a shift away from flecainide in ventricular arrhythmia, but the low noncardiac side effect profile of the agent allows for its continued use in a wide variety of supraventricular arrhythmias. ( J Cardiovasc Electrophysiol, Vol. 5, pp. 964–981. November 1994 )     

The effect of chronic atrial overdrive suppression pacing on the incidence of supraventricular tachyarrhythmias.

Chronic overdrive suppression pacing has been suggested as an effective adjunctive method for reducing the incidence of cardiac tachyarrhythmias. Documentation of effectiveness during prolonged monitoring is lacking, however. To assess more accurately the long-term utility of this treatment modality for medically refractory supraventricular tachyarrhythmias (SVTs), 10 patients with atrially implanted Intermedics Intertach pacemakers were randomly assigned to either a low or a high bradycardia (back-up) pacing rate. SVT counts were performed during matching follow-up periods both at the initial rate and after rate crossover. The primary antitachycardia modality of this pacemaker (P mod) provides burst pacing to terminate tachycardia episodes, and P mod counters were utilized to quantitate SVT episodes. Tachycardia termination algorithms were programmed to "no restart" and were not changed during the study. The P mod use counter, therefore, reflected the number of discrete episodes of SVTs. Pacemaker implantation diagnoses include atrial flutter, concealed bypass tract, AV nodal reentry, intraatrial reentry, and Wolff-Parkinson-White associated tachycardia. Patient age was 59 +/- 18 yrs. The average pacemaker back-up low rate was 45.7 +/- 4 versus a back-up high rate of 85.1 +/- 2 beats/min. Follow-up was for 57.4 days +/- 33 days at the low rate and 57.3 days +/- 34 days at the high rate (r = 0.99). There was no difference in SVT incidence with a P mod usage of 98.4 +/- 106 at the low rate and 100.8 +/- 94 at the high rate (p = NS). In this blinded, randomized cross-over trial, chronic atrial overdrive suppression pacing did not reduce the overall incidence of SVT episodes during prolonged monitoring.     

Efficacy and Mechanism of Intravenous Sotalol for Termination of Paroxysmal Supraventricular Tachycardia

ＳＶＴ ,ｉｎｃｌｕｄｉｎｇＡＶＲＴａｎｄＡＶＮＲＴ ,ｉｓａｋｉｎｄｏｆａｒｒｈｙｔｈｍｉａｏｆｔｅｎｓｅｅｎｉｎｃｌｉｎｉｃａｌｐｒａｃ ｔｉｃｅ .Ｓｏｔａｌｏｌ,ａｃｌａｓｓⅢａｎｔｉ ａｒｒｈｙｔｈｍｉｃｄｒｕｇｗｉｔｈａｄｄｉｔｉｏｎａｌβ ｂｌｏｃｋｉｎｇａｇｅｎｔｐｒｏｐｅｒｔｉｅｓ ,ｈａｓｂｅｅｎｗｉｄｅｌｙｕｓｅｄｔｏｔｒｅａｔｖａｒｉｏｕｓａｒｒｈｙｔｈｍｉａ(ｓｕｐｒａ ｖｅｎｔｒｉｃｕｌａｒａｎｄｖｅｎｔｒｉｃｕｌａｒ)ｅｆｆｉｃｉｅｎｔｌｙｉｎｗｅｓｔｅｒｎｃｏｕｎｔｒｉｅｓ[1 9]…     

Postoperative Intensive Care Treatment after Esophageal Resection

The aim of this article is to give a short review of problems associated with the intensive caretreatment of patients after esophageal resection.Pulmonary dysfunction,supraventricular tachyarrhyth-mia,anastomotie leakage and mental disorders are the topics covered.Systemic inflammatory reaction andsepsis is the linking topic between these specific complications.Pulmonary dysfunction having an incidenceof up to 40% is the most important complication.Low tidal volume ventilation,pain management includingepidural analgesia and early tracheostomy are the mainstay of therapy.Supraventricular tachyarrhythmiais an early indicator of emerging complications.Its symptomatic treatment is standardized using electriccardioversion,beta-blockers and amiodarone.Anastomotic leakage must be suspect in any septic episode.Endoscopy and contrast studies allow for precise diagnosis.Interventional endoscopy is increasingly suc-cessful in the therapy of these leakages.Microbiological surveillance and specific antibiotic therapy ensurethat a complication does not cause a septic cascade leading to multiorgan failure.The workload on ICUcaused by a patient after esophageal resection still exceeds that of most other patients with gastrointestinalsurgery.     

普罗帕酮治疗阵发性室上性心动过速的疗效观察

目的:总结评价普罗帕酮治疗阵发性室上性心动过速的疗效及安全性。方法:40例阵发性室上性心动过速患者,在心电监护下,给予普罗帕酮70mg静脉注射,10min内注射完成;首剂未能转律者,再每10min静脉注射普罗帕酮35mg,最大累积用量不超过175mg。复律后给予口服普罗帕酮150~200mg,每日3次维持治疗。观察开始给药后的转复率及不良反应的发生情况。结果:31例(31/40,77.5%)首剂即转窦性心律,6例追加剂量后转为窦性心律,总有效率92.5%(37/40)。继续予口服普罗帕酮治疗半年以上,未见严重不良反应,未见复发者。结论:普罗帕酮治疗阵发性室上性心动过速,疗效显著且不良反应轻微。     

硫酸镁治疗室上性快速心律失常

作者用硫酸镁治疗室上性快速心律失常25例,结果:阵发性室上性心动过速10例中6例作终止治疗,4例显效,4例作预防性治疗,3例好转;紊乱性房性心动过速3例于治疗后1小时至2日内纠正;快速房颤4例在治疗后半小时内心室率得到缓解;非阵发性交界区心动过速8例在治疗后10小时至2日内纠正。表明硫酸镁为治疗室上性快速心律失常的一种有效制剂。