Hemodynamic Effects and Clinical Determinants of Defibrillation Threshold for Transvenous Atrial Defibrillation Using Biatrial Biphasic Shocks in Patients with Chronic Atrial Fibrillation

We assessed the relationship between the hemodynamic changes and shock intensity in transvenous atrial defibrillation for chronic AF. The correlation between the clinical profile and atrial DFT and the factors predicting maintenance of SR after successful defibrillation were also investigated. Atrial defibrillation using entirely transvenoas leads has been investigated as an alternative means of managing patients with AF. However, the hemodynamic consequence of this technique and the clinical factors predicting defibrillation efficacy have not been evaluated. Thirty-seven patients with chronic AF (4 weeks to 60 months) underwent transvenoas atrial defibrillation. Defibrillation was performed by delivering R wave synchronized, biphasic (3/3 ms) shocks with step-up voltages (20–400 V) between defibrillation catheters in the anterolateral right atrium and the distal coronary sinus. Clinical profile of the patients, the DFT, arterial blood pressure, and RH interval during defibrillation and the 6-month recurrence rate were determined. SR was restored in 33 (89%) of 37 patients and the DFT was 3.7 ± 1.4 J (317 ± 58 V). Transvenous atrial defibrillation resulted in a mild reduction in blood pressure (6 ± 10 mmHg), but substantial prolongation of longest postshock RR intervals (507 ± 546 ms), which were significantly related to the shock intensity (r = 0.5, P < 0.001). There was no ventricular proarrhythmia. The patients'age, body weight, duration of AF, left atrial diameter, and ejection fraction were not related to the success of defibrillation, not the 6-month maintenance rate of SR (39%). However, the patients'age was related to DFT. Apart from transient reduction in blood pressure and shock related pauses that may require backup pacing, transvenous biatrial defibrillation was a highly effective and well-tolerated technique. The absence of clinical determinant for successful defibrillation suggests that restoring SR by transvenous atrial defibrillation could be attempted in most patients with chronic AF.     

Refractory Venous Leg Ulcers: A Study of Risk Factors

BACKGROUND: Although certain risk factors for poor healing of leg ulcers have been identified, data concerning the characteristics of refractory ulcers have not been specifically studied in the literature. OBJECTIVE: To study the characteristics of refractory venous leg ulcers. METHODS: We retrospectively studied prognostic factors for healing in patients with refractory venous leg ulcers followed and treated in our dermatology department between January 1993 and January 2000. Each patient included in this study was compared with two patients matched for age and gender and presenting leg ulcers with normal healing, followed during the same period. RESULTS: Thirty-two of 571 patients with leg ulcers were included. The study population consisted of 20 females and 12 males with a mean age 73.5 years. The control population comprised 64 patients, 40 females and 24 males, with a mean age of 73 years. Univariate analysis demonstrated the negative prognostic impact of several previously identified factors (including surface area and history of the ulcer). In particular, multivariate analysis identified four main risk factors for refractory ulcer that are often associated in these patients: associated arterial disease, presence of post-thrombotic popliteal sequelae, recurrence of the ulcer, and disability. CONCLUSION: Four main risk factors that are often associated were identified, indicating the multifactorial nature of these refractory ulcers.     

Abnormal Vasovagal Reaction, Autonomic Function, and Heart Rate Variability in Patients with Paroxysmal Atrial Fibrillation

The aim of this study was to evaluate the cardiovascular autonomic function and vasovagal reaction in patients with paroxysmal atrial fibrillation without significant structural heart disease. Twenty-eight patients with paroxysmal atrial fibrillation (9 patients were categorized to have autonomic-mediated atrial fibrillation while atrial fibrillation in other patients was nonautonomic mediated) and 19 normal control subjects were recruited. Cardiovascular autonomic function tests included measuring heart rate response to standing, deep breathing, Valsalva maneuver, baroreflex sensitivity, 24-hour heart rate variability, and also head-up tilt test. Compared with normal subjects, no significant autonomic dysfunction was found in patients with autonomic-mediated and nonautonomicmediated atrial fibrillation. All subjects had negative baseline tilt test. With isoproterenol provocation, six patients developed atrial fibrillation. Four of 9 patients and 3 of 19 patients with autonomic mediated and nonautonomic mediated atrial fibrillation had a positive tilt test respectively, while none occurred in the controls. A significant percentage (32%) of patients with paroxysmal atrial fibrillation had episodes of atrial fibrillation provoked by changes in autonomic tone, although there was no underlying abnormal cardiac autonomic function nor sympathetic-parasympathetic imbalance. A heightened susceptibility to vasovagal cardiovascular response may have important implications on the occurrence and symptomatology of patients with paroxysmal atrial fibrillation.     

A Comparison of Transvenous Atrial Defibrillation of Acute and Chronic Atrial Fibrillation and the Effect of Intravenous Sotalol on Human Atrial Defibrillation Threshold

The comparative efficacy and safety of transvenous defibrillation for acute and chronic AF and the effect of antiarrhythmic agents on this therapy have not been evaluated. Transvenous atrial defibrillation was performed in 25 patients with chronic AF and 13 patients with acute AF by delivering R wave synchronized, biphasic shocks between the right atrium and coronary sinus. The lowest energy and voltage resulting in successful defibrillation were considered to be atrial defibrillation threshold (ADFT). Intravenous sotalol (1.5 mg/kg) was thengiven over 15 minutes and ADFT was determined again. The mean ADFT was 1.5 /and 3.6 J for acute and chronic AF, respectively, and the threshold was highly reproducible. Sotaloi reduced ADFT in patients with acute AF while the reduction in chronic AF group was not significant. There was no significant increase in creatinine kinase nor reduction in blood pressure, but prolonged pause after successful defibrillation required ventricular supporting pacing. We conclude that transvenous atrial defibrillation is a safe and effective means for defibrillating both acute and chronic AF. ADFT was lower in acute AF than in chronic AF. ADFT was highly reproducible during repeated defibrillation. Sotalol reduced ADFT in acute AF and to a lesser extent in chronic AF, and increased the defibrillation success rate. Ventricular pacing will often be required because of prolonged pause after successful defibrillation.     

Benign recurrent intrahepatic cholestasis in a Chinese girl

A 15 year old Chinese girl presented with features of benign recurrent intrahepatic cholestasis, confirmed by liver biopsies performed during attack and remission. Her only younger brother also has features of this syndrome. Serial biochemistry monitoring during a recent attack demonstrated that a rise in the serum bile acids preceded the clinical onset of symptoms and the rise in serum bilirubin and ductal enzymes by 8 weeks. Whether this earlier rise in serum bile acids is related to the pathogenetic mechanism of this syndrome remains to be elucidated.     

阿尔茨海默病动物模型研究

阿尔茨海默病(Alzheimer's disease,AD)是一种神经退行性疾病,其临床表现主要是随着年龄增长,学习能力逐渐低下及行为、表达能力等出现障碍.模拟AD疾病病理发展的动物模型是研究此疾病的必要工具.目前已经成功建立了很多转基因动物模型,包括APPPS1,PS1/PS1,Tau 蛋白转基因小鼠及快速老化SAMP8小鼠模型.合适的动物模型在AD的病理机制研究及药物研发方面具有极其重要的作用.本文主要综述目前最常见的AD动物模型以及其在药物研发的作用.     

Synergism of chronic alcoholism and hepatitis B infection in liver disease

One hundred and fifty-seven patients with alcoholic liver disease were studied. Hepatitis B surface antigen (HBsAg) was positive in 20.4% of the patients. Those who were positive for the HBsAg presented at an earlier age, had a lower albumin level, a higher globulin level, a more prolonged prothrombin time, were more likely to have features of cirrhosis in the liver biopsy, and were probably more likely to suffer from hepatic encephalopathy in the follow-up compared with those negative for HBsAg. The mortality of subjects was low both on admission and during follow-up. It is concluded that chronic alcoholism and hepatitis B virus infection act synergistically in producing more severe liver damage and causing cirrhosis at a younger age compared with chronic alcoholism alone. One possible reason for the low mortality of the patients might have been their relatively good nutritional status.